WO2002042521A1 - Fabrication apparatus and method - Google Patents

Fabrication apparatus and method Download PDF

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Publication number
WO2002042521A1
WO2002042521A1 PCT/GB2001/005169 GB0105169W WO0242521A1 WO 2002042521 A1 WO2002042521 A1 WO 2002042521A1 GB 0105169 W GB0105169 W GB 0105169W WO 0242521 A1 WO0242521 A1 WO 0242521A1
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WO
WIPO (PCT)
Prior art keywords
powder
precursor
carrier medium
precursor material
deposition region
Prior art date
Application number
PCT/GB2001/005169
Other languages
French (fr)
Inventor
Kwang-Leong Choy
Isaac Tsz Hong Chang
Original Assignee
Innovative Materials Processing Technologies Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Innovative Materials Processing Technologies Limited filed Critical Innovative Materials Processing Technologies Limited
Priority to AU2002223874A priority Critical patent/AU2002223874A1/en
Publication of WO2002042521A1 publication Critical patent/WO2002042521A1/en

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/30—Electron-beam or ion-beam tubes for localised treatment of objects
    • H01J37/317—Electron-beam or ion-beam tubes for localised treatment of objects for changing properties of the objects or for applying thin layers thereon, e.g. for ion implantation
    • H01J37/3178—Electron-beam or ion-beam tubes for localised treatment of objects for changing properties of the objects or for applying thin layers thereon, e.g. for ion implantation for applying thin layers on objects
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
    • B29C41/34—Component parts, details or accessories; Auxiliary operations
    • B29C41/36—Feeding the material on to the mould, core or other substrate
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/10—Processes of additive manufacturing
    • B29C64/141—Processes of additive manufacturing using only solid materials
    • B29C64/153—Processes of additive manufacturing using only solid materials using layers of powder being selectively joined, e.g. by selective laser sintering or melting
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C24/00—Coating starting from inorganic powder
    • C23C24/08—Coating starting from inorganic powder by application of heat or pressure and heat
    • C23C24/10—Coating starting from inorganic powder by application of heat or pressure and heat with intermediate formation of a liquid phase in the layer
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C26/00—Coating not provided for in groups C23C2/00 - C23C24/00
    • C23C26/02—Coating not provided for in groups C23C2/00 - C23C24/00 applying molten material to the substrate
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
    • B29K2995/0037—Other properties
    • B29K2995/0072—Roughness, e.g. anti-slip
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
    • B29K2995/0037—Other properties
    • B29K2995/0072—Roughness, e.g. anti-slip
    • B29K2995/0074—Roughness, e.g. anti-slip patterned, grained
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

Definitions

  • the present invention relates to an apparatus for and method of fabricating material structures, in particular fabricating surface features, such as by texturing and patterning, surface coatings and functional three-dimensional components.
  • micromachining involves the removal of surface material using a range of techniques including chemical etching [1], dry etching [2], lithography [3] and ablation by electromagnetic radiation or ion beam [4].
  • Microfabrication involves the deposition of layers of material at specific regions on the surface of components using vapour deposition processing or plating techniques [5].
  • the components fabricated using these techniques always suffer from a relatively poor surface finish owing to the use of coarse powders.
  • the parts fabricated by SLS and 3DP can also suffer from low mechanical strength owing to low density or excessive resin, and so require additional processing steps such as the de-binding of resin and heat treatment for densification. This can lead to undesirable shrinkage which results in poor dimensional control.
  • the present invention provides a fabrication apparatus for fabricating material structures, comprising: a substrate support for supporting a substrate; a heating unit operable to provide a beam of radiation for heating a deposition region at the substrate and melting powder of a precursor material delivered thereto, which powder melt on cooling providing a solid material deposit, wherein the radiation beam is movable relative to the substrate support such as to enable the fabrication of a material structure by development of material deposits; a material delivery unit for delivering precursor material to the deposition region, the precursor material including a powder; and a material guiding unit for charging the powder of the precursor material and guiding the same in delivery to the deposition region.
  • the material structure is a surface feature.
  • the surface feature is a pattern.
  • the surface feature is a texture
  • the surface feature comprises a plurality of material deposits.
  • the material structure comprises a surface coating.
  • the surface coating is at least partially porous and comprises a plurality of material deposits.
  • the material structure comprises a three-dimensional component.
  • the material structure comprises a single layer.
  • the material structure comprises a plurality of layers.
  • the material structure is a compositionally-graded structure.
  • the material structure is a composite structure.
  • the powder has an average diameter of less than about 20 ⁇ m.
  • the powder has an average diameter of less than about 10 ⁇ m.
  • the precursor material comprises a powder contained in a fluid carrier medium.
  • the carrier medium includes a liquid, which liquid can be delivered as an aerosol.
  • the carrier medium includes a gel.
  • the carrier medium includes a powder.
  • the carrier medium includes a gas.
  • the carrier medium includes a reactive medium.
  • the carrier medium comprises a solvent.
  • the heating unit comprises a laser which is operable to provide a laser beam for heating the deposition region.
  • the heating unit comprises an electron beam generator which is operable to provide an electron beam for heating the deposition region.
  • the material delivery unit comprises at least one material reservoir for containing at least one precursor material, and a delivery channel for delivering the at least one precursor material towards the substrate.
  • the delivery channel includes a nozzle head having a delivery aperture for directing the precursor material.
  • the delivery aperture has a lateral dimension of not more than about 6 mm.
  • the delivery aperture has a lateral dimension of from about 3 mm to about 6 mm.
  • the delivery aperture is co-axial with the radiation beam.
  • the material delivery unit comprises a plurality of material reservoirs for containing different precursor materials, and the material delivery unit is operably configured selectively to deliver precursor material from one or more of the material reservoirs.
  • the material guiding unit comprises a high voltage supply for charging the powder of the precursor material and a field guiding element for guiding the powder of the precursor material in delivery to the deposition region.
  • the field guiding element comprises an electromagnetic lens.
  • the substrate support comprises a movable table.
  • the apparatus further comprises: a reactive medium supply unit for supplying a reactive medium to the deposition region.
  • the reactive medium comprises an aerosol.
  • the reactive medium comprises one or more gases.
  • the precursor material can include a reactive component, as a powder or liquid, to facilitate treatment by the radiation beam.
  • a reactive component as a powder, liquid, for example in the form of a stream, droplets or an aerosol, or gas, can be delivered to the deposition region to facilitate treatment by the radiation beam.
  • the present invention provides a fabrication apparatus for fabricating material structures, comprising: a substrate support for supporting a substrate; a heating unit operable to provide a beam of radiation for heating a deposition region at the substrate and melting powder of a precursor material delivered thereto, which powder melt on cooling providing a solid material deposit, wherein the radiation beam is movable relative to the substrate support such as to enable the fabrication of a material structure by development of material deposits; and a material delivery unit for delivering precursor material to the deposition region, the precursor material comprising powder contained in a fluid carrier medium.
  • the material structure is a surface feature.
  • the surface feature is a pattern.
  • the surface feature is a texture.
  • the surface feature comprises a plurality of material deposits.
  • the material structure comprises a surface coating.
  • the surface coating is at least partially porous and comprises a plurality of material deposits.
  • the material structure comprises a three-dimensional component.
  • the material structure comprises a single layer.
  • the material structure comprises a plurality of layers.
  • the material structure is a compositionally-graded structure.
  • the material structure is a composite structure.
  • the powder has an average diameter of less than about 20 ⁇ m.
  • the powder has an average diameter of less than about 10 ⁇ m.
  • the carrier medium includes a liquid, which liquid can be delivered as an aerosol.
  • the carrier medium includes a gel.
  • the carrier medium includes a powder.
  • the carrier medium includes a gas.
  • the carrier medium includes a reactive medium.
  • the carrier medium comprises a solvent.
  • the heating unit comprises a laser which is operable to provide a laser beam for heating the deposition region.
  • the heating unit comprises an electron beam generator which is operable to provide an electron beam for heating the deposition region.
  • the material delivery unit comprises at least one material reservoir for containing at least one precursor material, and a delivery channel for delivering the at least one precursor material towards the substrate.
  • the delivery channel includes a nozzle head having a delivery aperture for directing the precursor material.
  • the delivery aperture has a lateral dimension of not more than about 6 mm.
  • the delivery aperture has a lateral dimension of from about 3 mm to about 6 mm.
  • the delivery aperture is co-axial with the radiation beam.
  • the material delivery unit comprises a plurality of material reservoirs for containing different precursor materials, and the material delivery unit is operably configured selectively to deliver precursor material from one or more of the material reservoirs.
  • the apparatus further comprises: a material guiding unit for charging the powder of the precursor material and guiding the same in delivery to the deposition region.
  • the material guiding unit comprises a high voltage supply for charging the powder of the precursor material and a field guiding element for guiding the powder of the precursor material in delivery to the deposition region.
  • the field guiding element comprises an electromagnetic lens.
  • the substrate support comprises a movable table.
  • the apparatus further comprises: a reactive medium supply unit for supplying a reactive medium to the deposition region.
  • the reactive medium comprises an aerosol.
  • the reactive medium comprises one or more gases.
  • the present invention provides a method of fabricating material structures, comprising the steps of: delivering a precursor material comprising a powder; charging the powder of the precursor material; guiding the charged powder of the precursor material to a deposition region at a substrate; heating the deposition region with a beam of radiation such as to melt powder of a precursor material delivered thereto, which powder melt when cooled provides a solid material deposit; and moving the substrate relative to the radiation beam such as to enable the fabrication of a material structure by development of material deposits.
  • the material structure is a surface feature.
  • the surface feature is a pattern.
  • the surface feature is a texture
  • the surface feature comprises a plurality of material deposits.
  • the material structure comprises a surface coating.
  • the surface coating is at least partially porous and comprises a plurality of material deposits.
  • the material structure comprises a three-dimensional component.
  • the material structure comprises a single layer.
  • the material structure comprises a plurality of layers.
  • the material structure is a compositionally-graded structure.
  • the material structure is a composite structure.
  • the powder has an average diameter of less than about 20 ⁇ m.
  • the powder has an average diameter of less than about 10 ⁇ m.
  • the precursor material comprises a powder contained in a fluid carrier medium.
  • the carrier medium includes a liquid, which liquid can be in the form of an aerosol.
  • the carrier medium includes a gel.
  • the carrier medium includes a powder.
  • the carrier medium includes a gas.
  • the carrier medium comprises a reactive medium.
  • the carrier medium comprises a solvent.
  • the radiation beam is a laser beam.
  • the radiation beam is an electron beam.
  • the step of delivering a precursor material comprises the step of: selectively delivering one or more precursor materials.
  • the step of guiding the charged powder of the precursor material comprises the step of: applying a guiding field to guide the charged powder of the precursor material.
  • the field is an electromagnetic field.
  • the method further comprises the step of: supplying a reactive medium to the deposition region.
  • the reactive medium comprises an aerosol.
  • the reactive medium comprises one or more gases.
  • the present invention provides a method of fabricating material structures, comprising the steps of: delivering a precursor material comprising a powder contained in a fluid carrier medium to a deposition region at a substrate; heating the deposition region with a beam of radiation such as to melt powder of a precursor material delivered thereto, which powder melt when cooled provides a solid material deposit; and moving the substrate relative to the radiation beam such as to enable the fabrication of a material structure by development of material deposits.
  • the material structure is a surface feature.
  • the surface feature is a pattern. In another preferred embodiment the surface feature is a texture.
  • the surface feature comprises a plurality of material deposits.
  • the material structure comprises a surface coating.
  • the surface coating is at least partially porous and comprises a plurality of material deposits.
  • the structure comprises a three-dimensional component.
  • the material structure comprises a single layer.
  • the material structure comprises a plurality of layers.
  • the material structure is a compositionally-graded structure.
  • the material structure is a composite structure.
  • the powder has an average diameter of less than about 20 ⁇ m.
  • the powder has an average diameter of less than about 10 ⁇ m.
  • the carrier medium includes a liquid, which liquid can be delivered as an aerosol.
  • the carrier medium includes a gel.
  • the carrier medium includes a powder.
  • the carrier medium includes a gas.
  • the carrier medium comprises a reactive medium.
  • the carrier medium comprises a solvent.
  • the radiation beam is a laser beam.
  • the radiation beam is an electron beam.
  • the step of delivering a precursor material comprises the step of: selectively delivering one or more precursor materials.
  • the method further comprises the steps of: charging the powder of the precursor material; and guiding the charged powder of the precursor material to a deposition region at a substrate.
  • the step of guiding the charged powder of the precursor material comprises the step of: applying a guiding field to guide the charged powder of the precursor material.
  • the field is an electromagnetic field.
  • the method further comprises the step of: supplying a reactive medium to the deposition region.
  • the reactive medium comprises an aerosol.
  • the reactive medium comprises one or more gases.
  • the fabrication technique of the present invention is an additive approach and allows for the selective texturing and patterning of component surfaces to provide well-defined surface features, and also for the solid freeform fabrication of three-dimensional components which have an excellent surface finish and do not require any expensive and time consuming finishing operations.
  • the surface features and three-dimensional components can be fabricated as dense or porous structures, with varying porosity, composition level and dimensions, typically from the millimetre to micron scale.
  • surface features and porosity can be fabricated having any required spacing, in one embodiment periodic, and orientation.
  • This fabrication technique is also a rapid fabrication technique, and is sufficiently flexible as to enable the fabrication of components of any size, typically from small, miniaturized components to large engineering components.
  • the fabrication technique allows for fabrication in both open and closed environments.
  • This fabrication technique is a simple technique, in a preferred embodiment a single-step technique, and is very different to the multi-stage processes of existing micromachining and microfabrication techniques.
  • this fabrication technique avoids the need to use masks and enables the fabrication of surface features on much larger component areas, where the components can be planar or non planar.
  • this fabrication technique provides for excellent bonding between the deposited material and the underlying substrate .
  • This technique is also quite different to existing laser material processing techniques, for example, laser welding which is directed to the fabrication of continuous solid joints between metal sheets, laser cladding which is directed to the fabrication of continuous solid coating layers, and laser-based rapid prototyping which is directed to the fabrication of fully-dense, solid three-dimensional components.
  • the laser welding technique utilises metal sheets.
  • the laser cladding and laser-based rapid prototyping techniques require the use of coarse metal powders, typically having an average particle size of much greater than 20 ⁇ m, which are transported by an inert gas.
  • the use of a coarse powder is an essential requirement of these techniques as otherwise the powder would become airborne in the atmosphere.
  • the resulting surface finish is poor and requires surface finishing operations to provide an acceptable surface finish.
  • This fabrication technique enables the deposition of a wide range of materials including metals, alloys, intermetallics, ceramics, semiconductors, polymers and inorganic-organic hybrids, and can be deposited as composite, functionally-graded or compositionally- graded materials.
  • This fabrication technique is also such as to provide a high material yield with minimal material wastage in the production of the surface features, and moreover allows for recycling of any unused powder material.
  • the fabrication technique of the present invention finds application in a wide range of markets, such as domestic, transportation including aerospace, scientific instrument, chemical, thermal, optical, electrical, electronics and biomedical industries.
  • domestic appliances where surface appearance and/or improved surface wettability can be achieved by selective surface texturing;
  • cooling components where effective cooling can be achieved through turbulent fluid flow around a selectively textured surface;
  • biomedical implants where a selectively porous surface is beneficial for in-growth of tissue;
  • fuel cell components where a selectively porous layer is utilised to guide gaseous fuel for electrochemical reaction at specific regions;
  • sensors where well-defined porous surface regions are required to provide enhanced spatial selectivity;
  • miniaturized actuators where surface features having a high aspect ratio are required;
  • electromagnetic radiation diffiisers where a well-defined, periodic surface texture is beneficial to the scattering of radiation;
  • superconductors for producing electromagnetic radiation diffiisers where a well-defined, periodic surface texture
  • superconductors where
  • Figure 1 illustrates a fabrication apparatus in accordance with a first embodiment of the present invention
  • Figure 2 illustrates a fabrication apparatus in accordance with a second embodiment of the present invention
  • Figure 3 illustrates a cross-sectional SEM of a stainless steel line deposited on a stainless steel substrate using the fabrication apparatus of Figure 2; and Figure 4 illustrates a plan view SEM of a surface pattern comprising stainless steel deposits as deposited on a square stainless steel substrate using the fabrication apparatus of Figure 2.
  • Figure 1 illustrates a fabrication apparatus in accordance with a first embodiment of the present invention.
  • the apparatus comprises a substrate support 1 on which a substrate 3, in this embodiment a planar substrate, is located for the deposition of material deposits.
  • the substrate support 1 comprises a movable table for moving the substrate 3 in x, y and z directions. In this embodiment the substrate support 1 can be moved at speeds of up to 200 mm per second, but preferred operation is in the range of from about 2 to about 40 mm per second.
  • the apparatus further comprises a heating unit 5 for providing a beam of radiation, in this embodiment a high-power carbon dioxide laser for providing a laser beam, and a focusing lens 7 for providing a focused radiation beam at a deposition region at the substrate 3.
  • the focused radiation beam is such as to heat the deposition region at the substrate 3 and cause the melting of deposited material such as to form a melt pool while irradiated by the radiation beam, which melt pool forms a solid deposit on cooling.
  • the heating unit 5 includes a shutter which is operable to obstruct the radiation beam and enable the selective transmission of the radiation beam, which selective transmission enables the selective formation of surface textures or patterns and the development of porous structures.
  • the heating unit 5 could comprise a UN laser. Such a laser, in providing radiation having a shorter wavelength, provides for a smaller beam dimension.
  • the apparatus further comprises a material delivery unit 9 for delivering at least one precursor material to the deposition region such as to be irradiated by the radiation beam and transformed, in this embodiment following melting, to a solid material.
  • a material delivery unit 9 for delivering at least one precursor material to the deposition region such as to be irradiated by the radiation beam and transformed, in this embodiment following melting, to a solid material.
  • precursor material can be delivered at rates of up to about 5 gram per minute.
  • the precursor material comprises one of fine, dry powder particles, typically having an average particle size of less than 20 ⁇ m, or a suspension of such fine powder particles in a liquid-containing carrier medium, in this embodiment a solvent, such as water or ethanol, which is evaporated by the heat of the radiation beam.
  • the material delivery unit 9 comprises at least one material reservoir 11 which contains a supply of precursor material, and a delivery channel 13 for delivering precursor material to the deposition region.
  • the delivery channel 13 includes a nozzle head 15 at the distal end thereof for directing the delivery of precursor material.
  • the nozzle head 15 has a small internal diameter, in this embodiment less than about 6 mm, and typically in the range of from about 3 mm to about 6 mm.
  • the material delivery unit 9 includes a plurality of material reservoirs 11 such as to enable the selective delivery of ones of different precursor materials, and thereby enable the deposition of composite, functionally-graded or compositionally-graded materials.
  • the apparatus further comprises a material guiding unit for guiding the precursor material delivered from the nozzle head 15 of the delivery channel 13 of the material delivery unit 9 towards the deposition region.
  • the material guiding unit comprises a high voltage supply 17 which is connected to the nozzle head 15 and the substrate support 1 such as to charge the powder particles of the precursor material, and an electromagnetic lens 19 for focusing the charged powder particles of the precursor material onto the deposition region.
  • the electromagnetic lens 19 enables the lateral dimension of the deposit to be controlled as required.
  • the apparatus further comprises a reactive medium supply unit 20 for supplying a reactive medium, in this embodiment one or more gases, to the deposition region.
  • a reactive medium in this embodiment one or more gases
  • the apparatus further comprises a control unit 21 for controlling the operation of the substrate support 1 such as to move the substrate 3 when depositing material and thereby form material deposits as required, the heating unit 5, the material supply unit 9 in delivering precursor material to the deposition region, the high voltage supply 17 and electromagnetic lens 19 of the material guiding unit in focusing the precursor material onto the deposition region, and the reactive medium supply unit 20.
  • a control unit 21 for controlling the operation of the substrate support 1 such as to move the substrate 3 when depositing material and thereby form material deposits as required, the heating unit 5, the material supply unit 9 in delivering precursor material to the deposition region, the high voltage supply 17 and electromagnetic lens 19 of the material guiding unit in focusing the precursor material onto the deposition region, and the reactive medium supply unit 20.
  • the substrate support 1 is moved under the control of the control unit 21 such as to expose deposition regions onto which material deposits are to be formed to the radiation beam, and, at the same time, precursor material is delivered by the material delivery unit 9 at a predetermined rate and focused by the material guiding unit onto the deposition region at or just ahead of the radiation beam.
  • precursor material is delivered by the material delivery unit 9 at a predetermined rate and focused by the material guiding unit onto the deposition region at or just ahead of the radiation beam.
  • a surface texture or pattern can be deposited by the selective formation of material deposits, for example, lines or beads of material having a predetermined pattern, with the selective deposition of material deposits being achieved by pulsing the radiation beam.
  • a three-dimensional component can be fabricated by building up layers of material by the repeated scanning of the deposition surface, with the substrate support 1 being repeatedly lowered relative to the radiation beam for each layer such that the deposition surface is maintained at the focal point of the radiation beam.
  • the structure of the material deposits is influenced by the particle size of the powder, the power of the heating unit 5, the dimension of the radiation beam, the travelling speed of the substrate support 1, and the rate of delivery of the precursor material.
  • Figure 2 illustrates a fabrication apparatus in accordance with a second embodiment of the present invention.
  • the fabrication apparatus of this embodiment is quite similar to the fabrication apparatus of the above-described embodiment, and thus, in order to avoid unnecessary duplication of description, only the differences will be described in detail.
  • the fabrication apparatus of this embodiment differs from that of the above-described embodiment in that the nozzle head 15 of the delivery channel 13 is co-axial with the radiation beam, whereby precursor material is delivered under the action of gravity to the o
  • the material guiding unit in registration with the radiation beam, and in that the material guiding unit is omitted; this unit not being necessary since the delivery of precursor material is coincident with the radiation beam.
  • the material guiding unit could be incorporated. Operation is otherwise the same as for the above-described embodiment.
  • Figures 3 and 4 illustrate SEMs of material structures fabricated by the fabrication apparatus of this embodiment.
  • Figure 3 illustrates a cross-sectional view through a stainless steel line fabricated on a stainless steel plate.
  • the stainless steel line was fabricated with the substrate support 1 at a travelling speed of 2 mm per second, with the stainless deposit having a height of about 100 ⁇ m and a width of about 250 ⁇ m and being bonded firmly to the stainless plate.
  • Figure 4 illustrates a plan view of a 3 mm x 3 mm stainless steel deposit pattern fabricated on a stainless steel plate.
  • the pattern is bounded by a continuous stainless square which is defined by stainless lines, and includes two further squares therewithin which are defined by stainless beads, each having an average diameter of 250 ⁇ m. This configuration provides a graded porosity from the centre to the edge of the pattern.
  • the heating unit 5 can comprise an electron beam generator which provides an electron beam for heating the deposition region.

Abstract

A fabrication apparatus for and method of fabricating material structures, the apparatus comprising: a substrate support for supporting a substrate; a heating unit operable to provide a beam of radiation for heating a deposition region at the substrate and melting powder of a precursor material delivered thereto, which powder melt on cooling providing a solid material deposit, wherein the radiation beam is movable relative to the substrate support such as to enable the fabrication of a material structure by development of material deposits; a material delivery unit for delivering precursor material to the deposition region, the precursor material including a powder contained in a carrier medium: and a material guiding unit for charging the powder of the precursor material and guiding the same in delivery to the deposition region.

Description

FABRICATION APPARATUS AND METHOD
The present invention relates to an apparatus for and method of fabricating material structures, in particular fabricating surface features, such as by texturing and patterning, surface coatings and functional three-dimensional components.
There is an increasing demand for functional surfaces, and, as such, surface properties have become an important issue in component design. There are several known techniques for modifying surface properties. These include the modification of the surface material by alloy development. Alloy development is, however, relatively expensive, and, as such, does not lend itself to use with conventional materials. Other techniques for modifying surface properties include micromachining, which is a subtractive approach, and microfabrication, which is an additive approach. Micromachining involves the removal of surface material using a range of techniques including chemical etching [1], dry etching [2], lithography [3] and ablation by electromagnetic radiation or ion beam [4]. Microfabrication involves the deposition of layers of material at specific regions on the surface of components using vapour deposition processing or plating techniques [5]. These techniques do allow for the use of conventional materials, but, at least at present, the fabrication time is relatively long. As such, these techniques are not cost effective for large batch manufacturing, particularly where large surface areas are to be textured or patterned. Furthermore, most of these techniques require a mask to selectively deposit or remove surface material in developing the required surface textures or patterns. The production of such masks can be expensive, and is also time consuming.
There is also an increasing demand for the rapid fabrication of fully-dense engineering components directly from a computer-aided design (CAD) model, without requiring expensive, intermediate models in the development of new products. This is usually achieved by freeform fabrication technologies in which components are built layer-by- layer. The applications of these components range from pilot or production tooling to functional prototypes. At present, various commercially-available solid freeform fabrication techniques are used to fabricate metal parts. These include selective laser sintering (SLS) [6] which involves the laser heating of resin-coated metal powders, laser- engineered net shaping (LENS) [7] which involves the laser melting and solidification of metal powders, and 3D printing (3 DP) [8] which involves the selective printing of resin to glue metal powders together. However, the components fabricated using these techniques always suffer from a relatively poor surface finish owing to the use of coarse powders. The parts fabricated by SLS and 3DP can also suffer from low mechanical strength owing to low density or excessive resin, and so require additional processing steps such as the de-binding of resin and heat treatment for densification. This can lead to undesirable shrinkage which results in poor dimensional control.
There is therefore a need for a fabrication technique which is capable of producing precise surface features and functional components, in particular metal parts, directly from a computer aided-design (CAD) model, and which provides components having an improved surface finish, dimensional accuracy and mechanical strength as compared to those fabricated using existing techniques.
In one aspect the present invention provides a fabrication apparatus for fabricating material structures, comprising: a substrate support for supporting a substrate; a heating unit operable to provide a beam of radiation for heating a deposition region at the substrate and melting powder of a precursor material delivered thereto, which powder melt on cooling providing a solid material deposit, wherein the radiation beam is movable relative to the substrate support such as to enable the fabrication of a material structure by development of material deposits; a material delivery unit for delivering precursor material to the deposition region, the precursor material including a powder; and a material guiding unit for charging the powder of the precursor material and guiding the same in delivery to the deposition region.
In one embodiment the material structure is a surface feature.
In one preferred embodiment the surface feature is a pattern.
In another preferred embodiment the surface feature is a texture.
Preferably, the surface feature comprises a plurality of material deposits. In another embodiment the material structure comprises a surface coating.
Preferably, the surface coating is at least partially porous and comprises a plurality of material deposits.
In a further embodiment the material structure comprises a three-dimensional component.
In one embodiment the material structure comprises a single layer.
In another embodiment the material structure comprises a plurality of layers.
In one embodiment the material structure is a compositionally-graded structure.
In another embodiment the material structure is a composite structure.
Preferably, the powder has an average diameter of less than about 20 μm.
More preferably, the powder has an average diameter of less than about 10 μm.
Preferably, the precursor material comprises a powder contained in a fluid carrier medium.
In one embodiment the carrier medium includes a liquid, which liquid can be delivered as an aerosol.
In another embodiment the carrier medium includes a gel.
In a further embodiment the carrier medium includes a powder.
In a yet further embodiment the carrier medium includes a gas.
Preferably, the carrier medium includes a reactive medium. Preferably, the carrier medium comprises a solvent.
In one embodiment the heating unit comprises a laser which is operable to provide a laser beam for heating the deposition region.
In another embodiment the heating unit comprises an electron beam generator which is operable to provide an electron beam for heating the deposition region.
Preferably, the material delivery unit comprises at least one material reservoir for containing at least one precursor material, and a delivery channel for delivering the at least one precursor material towards the substrate.
More preferably, the delivery channel includes a nozzle head having a delivery aperture for directing the precursor material.
Still more preferably, the delivery aperture has a lateral dimension of not more than about 6 mm.
Yet more preferably, the delivery aperture has a lateral dimension of from about 3 mm to about 6 mm.
Preferably, the delivery aperture is co-axial with the radiation beam.
Preferably, the material delivery unit comprises a plurality of material reservoirs for containing different precursor materials, and the material delivery unit is operably configured selectively to deliver precursor material from one or more of the material reservoirs.
Preferably, the material guiding unit comprises a high voltage supply for charging the powder of the precursor material and a field guiding element for guiding the powder of the precursor material in delivery to the deposition region. More preferably, the field guiding element comprises an electromagnetic lens.
Preferably, the substrate support comprises a movable table.
Preferably, the apparatus further comprises: a reactive medium supply unit for supplying a reactive medium to the deposition region.
In one embodiment the reactive medium comprises an aerosol.
In another embodiment the reactive medium comprises one or more gases.
In one embodiment the precursor material can include a reactive component, as a powder or liquid, to facilitate treatment by the radiation beam.
In another embodiment a reactive component, as a powder, liquid, for example in the form of a stream, droplets or an aerosol, or gas, can be delivered to the deposition region to facilitate treatment by the radiation beam.
In another aspect the present invention provides a fabrication apparatus for fabricating material structures, comprising: a substrate support for supporting a substrate; a heating unit operable to provide a beam of radiation for heating a deposition region at the substrate and melting powder of a precursor material delivered thereto, which powder melt on cooling providing a solid material deposit, wherein the radiation beam is movable relative to the substrate support such as to enable the fabrication of a material structure by development of material deposits; and a material delivery unit for delivering precursor material to the deposition region, the precursor material comprising powder contained in a fluid carrier medium.
In one embodiment the material structure is a surface feature.
In one preferred embodiment the surface feature is a pattern.
In another preferred embodiment the surface feature is a texture. Preferably, the surface feature comprises a plurality of material deposits.
In another embodiment the material structure comprises a surface coating.
Preferably, the surface coating is at least partially porous and comprises a plurality of material deposits.
In a further embodiment the material structure comprises a three-dimensional component.
In one embodiment the material structure comprises a single layer.
In another embodiment the material structure comprises a plurality of layers.
In one embodiment the material structure is a compositionally-graded structure.
In another embodiment the material structure is a composite structure.
Preferably, the powder has an average diameter of less than about 20 μm.
More preferably, the powder has an average diameter of less than about 10 μm.
In one embodiment the carrier medium includes a liquid, which liquid can be delivered as an aerosol.
In another embodiment the carrier medium includes a gel.
In a further embodiment the carrier medium includes a powder.
In a still further embodiment the carrier medium includes a gas.
Preferably, the carrier medium includes a reactive medium. Preferably, the carrier medium comprises a solvent.
In one embodiment the heating unit comprises a laser which is operable to provide a laser beam for heating the deposition region.
In another embodiment the heating unit comprises an electron beam generator which is operable to provide an electron beam for heating the deposition region.
Preferably, the material delivery unit comprises at least one material reservoir for containing at least one precursor material, and a delivery channel for delivering the at least one precursor material towards the substrate.
More preferably, the delivery channel includes a nozzle head having a delivery aperture for directing the precursor material.
Still more preferably, the delivery aperture has a lateral dimension of not more than about 6 mm.
Yet more preferably, the delivery aperture has a lateral dimension of from about 3 mm to about 6 mm.
Preferably, the delivery aperture is co-axial with the radiation beam.
Preferably, the material delivery unit comprises a plurality of material reservoirs for containing different precursor materials, and the material delivery unit is operably configured selectively to deliver precursor material from one or more of the material reservoirs.
Preferably, the apparatus further comprises: a material guiding unit for charging the powder of the precursor material and guiding the same in delivery to the deposition region. More preferably, the material guiding unit comprises a high voltage supply for charging the powder of the precursor material and a field guiding element for guiding the powder of the precursor material in delivery to the deposition region.
Still more preferably, the field guiding element comprises an electromagnetic lens.
Preferably, the substrate support comprises a movable table.
Preferably, the apparatus further comprises: a reactive medium supply unit for supplying a reactive medium to the deposition region.
In one embodiment the reactive medium comprises an aerosol.
In another embodiment the reactive medium comprises one or more gases.
In a further aspect the present invention provides a method of fabricating material structures, comprising the steps of: delivering a precursor material comprising a powder; charging the powder of the precursor material; guiding the charged powder of the precursor material to a deposition region at a substrate; heating the deposition region with a beam of radiation such as to melt powder of a precursor material delivered thereto, which powder melt when cooled provides a solid material deposit; and moving the substrate relative to the radiation beam such as to enable the fabrication of a material structure by development of material deposits.
In one embodiment the material structure is a surface feature.
In one preferred embodiment the surface feature is a pattern.
In another preferred embodiment the surface feature is a texture.
Preferably, the surface feature comprises a plurality of material deposits.
In another embodiment the material structure comprises a surface coating. Preferably, the surface coating is at least partially porous and comprises a plurality of material deposits.
In a further embodiment the material structure comprises a three-dimensional component.
In one embodiment the material structure comprises a single layer.
In another embodiment the material structure comprises a plurality of layers.
In one embodiment the material structure is a compositionally-graded structure.
In another embodiment the material structure is a composite structure.
Preferably, the powder has an average diameter of less than about 20 μm.
More preferably, the powder has an average diameter of less than about 10 μm.
Preferably, the precursor material comprises a powder contained in a fluid carrier medium.
In one embodiment the carrier medium includes a liquid, which liquid can be in the form of an aerosol.
In another embodiment the carrier medium includes a gel.
In a further embodiment the carrier medium includes a powder.
In a still further embodiment the carrier medium includes a gas.
Preferably, the carrier medium comprises a reactive medium.
Preferably, the carrier medium comprises a solvent. In one embodiment the radiation beam is a laser beam.
In another embodiment the radiation beam is an electron beam.
Preferably, the step of delivering a precursor material comprises the step of: selectively delivering one or more precursor materials.
Preferably, the step of guiding the charged powder of the precursor material comprises the step of: applying a guiding field to guide the charged powder of the precursor material.
Preferably, the field is an electromagnetic field.
Preferably, the method further comprises the step of: supplying a reactive medium to the deposition region.
In one embodiment the reactive medium comprises an aerosol.
In another embodiment the reactive medium comprises one or more gases.
In a still further aspect the present invention provides a method of fabricating material structures, comprising the steps of: delivering a precursor material comprising a powder contained in a fluid carrier medium to a deposition region at a substrate; heating the deposition region with a beam of radiation such as to melt powder of a precursor material delivered thereto, which powder melt when cooled provides a solid material deposit; and moving the substrate relative to the radiation beam such as to enable the fabrication of a material structure by development of material deposits.
In one embodiment the material structure is a surface feature.
In one preferred embodiment the surface feature is a pattern. In another preferred embodiment the surface feature is a texture.
Preferably, the surface feature comprises a plurality of material deposits.
In another embodiment the material structure comprises a surface coating.
Preferably, the surface coating is at least partially porous and comprises a plurality of material deposits.
In a further embodiment the structure comprises a three-dimensional component.
In one embodiment the material structure comprises a single layer.
In another embodiment the material structure comprises a plurality of layers.
In one embodiment the material structure is a compositionally-graded structure.
In another embodiment the material structure is a composite structure.
Preferably, the powder has an average diameter of less than about 20 μm.
More preferably, the powder has an average diameter of less than about 10 μm.
In one embodiment the carrier medium includes a liquid, which liquid can be delivered as an aerosol.
In another embodiment the carrier medium includes a gel.
In a further embodiment the carrier medium includes a powder.
In a still further embodiment the carrier medium includes a gas.
Preferably, the carrier medium comprises a reactive medium. Preferably, the carrier medium comprises a solvent.
In one embodiment the radiation beam is a laser beam.
In another embodiment the radiation beam is an electron beam.
Preferably, the step of delivering a precursor material comprises the step of: selectively delivering one or more precursor materials.
Preferably, the method further comprises the steps of: charging the powder of the precursor material; and guiding the charged powder of the precursor material to a deposition region at a substrate.
Preferably, the step of guiding the charged powder of the precursor material comprises the step of: applying a guiding field to guide the charged powder of the precursor material.
More preferably, the field is an electromagnetic field.
Preferably, the method further comprises the step of: supplying a reactive medium to the deposition region.
In one embodiment the reactive medium comprises an aerosol.
In another embodiment the reactive medium comprises one or more gases.
The fabrication technique of the present invention is an additive approach and allows for the selective texturing and patterning of component surfaces to provide well-defined surface features, and also for the solid freeform fabrication of three-dimensional components which have an excellent surface finish and do not require any expensive and time consuming finishing operations. The surface features and three-dimensional components can be fabricated as dense or porous structures, with varying porosity, composition level and dimensions, typically from the millimetre to micron scale. In particular, surface features and porosity can be fabricated having any required spacing, in one embodiment periodic, and orientation. This fabrication technique is also a rapid fabrication technique, and is sufficiently flexible as to enable the fabrication of components of any size, typically from small, miniaturized components to large engineering components. Moreover, the fabrication technique allows for fabrication in both open and closed environments.
This fabrication technique is a simple technique, in a preferred embodiment a single-step technique, and is very different to the multi-stage processes of existing micromachining and microfabrication techniques. In particular, this fabrication technique avoids the need to use masks and enables the fabrication of surface features on much larger component areas, where the components can be planar or non planar. Moreover, this fabrication technique provides for excellent bonding between the deposited material and the underlying substrate .
This technique is also quite different to existing laser material processing techniques, for example, laser welding which is directed to the fabrication of continuous solid joints between metal sheets, laser cladding which is directed to the fabrication of continuous solid coating layers, and laser-based rapid prototyping which is directed to the fabrication of fully-dense, solid three-dimensional components. The laser welding technique utilises metal sheets. Whereas, the laser cladding and laser-based rapid prototyping techniques require the use of coarse metal powders, typically having an average particle size of much greater than 20 μm, which are transported by an inert gas. The use of a coarse powder is an essential requirement of these techniques as otherwise the powder would become airborne in the atmosphere. As a consequence of utilising a coarse metal powder, the resulting surface finish is poor and requires surface finishing operations to provide an acceptable surface finish.
This fabrication technique enables the deposition of a wide range of materials including metals, alloys, intermetallics, ceramics, semiconductors, polymers and inorganic-organic hybrids, and can be deposited as composite, functionally-graded or compositionally- graded materials. This fabrication technique is also such as to provide a high material yield with minimal material wastage in the production of the surface features, and moreover allows for recycling of any unused powder material.
The fabrication technique of the present invention finds application in a wide range of markets, such as domestic, transportation including aerospace, scientific instrument, chemical, thermal, optical, electrical, electronics and biomedical industries. Particular examples include: (i) domestic appliances where surface appearance and/or improved surface wettability can be achieved by selective surface texturing; (ii) cooling components where effective cooling can be achieved through turbulent fluid flow around a selectively textured surface; (iii) biomedical implants where a selectively porous surface is beneficial for in-growth of tissue; (iv) biomedical implants with specific dimensions tailored to individual patients; (v) fuel cell components where a selectively porous layer is utilised to guide gaseous fuel for electrochemical reaction at specific regions; (vi) sensors where well-defined porous surface regions are required to provide enhanced spatial selectivity; (vii) miniaturized actuators where surface features having a high aspect ratio are required; (viii) electromagnetic radiation diffiisers where a well-defined, periodic surface texture is beneficial to the scattering of radiation; (ix) superconductors; (x) pilot or production toolings for plastic/metal injection moulding or metalworking tools; and (xi) functional prototypes of engineering parts.
Preferred embodiments of the present invention will now be described hereinbelow by way of example only with reference to the accompanying drawings, in which:
Figure 1 illustrates a fabrication apparatus in accordance with a first embodiment of the present invention;
Figure 2 illustrates a fabrication apparatus in accordance with a second embodiment of the present invention;
Figure 3 illustrates a cross-sectional SEM of a stainless steel line deposited on a stainless steel substrate using the fabrication apparatus of Figure 2; and Figure 4 illustrates a plan view SEM of a surface pattern comprising stainless steel deposits as deposited on a square stainless steel substrate using the fabrication apparatus of Figure 2.
Figure 1 illustrates a fabrication apparatus in accordance with a first embodiment of the present invention.
The apparatus comprises a substrate support 1 on which a substrate 3, in this embodiment a planar substrate, is located for the deposition of material deposits. The substrate support 1 comprises a movable table for moving the substrate 3 in x, y and z directions. In this embodiment the substrate support 1 can be moved at speeds of up to 200 mm per second, but preferred operation is in the range of from about 2 to about 40 mm per second.
The apparatus further comprises a heating unit 5 for providing a beam of radiation, in this embodiment a high-power carbon dioxide laser for providing a laser beam, and a focusing lens 7 for providing a focused radiation beam at a deposition region at the substrate 3. The focused radiation beam is such as to heat the deposition region at the substrate 3 and cause the melting of deposited material such as to form a melt pool while irradiated by the radiation beam, which melt pool forms a solid deposit on cooling. In this embodiment the heating unit 5 includes a shutter which is operable to obstruct the radiation beam and enable the selective transmission of the radiation beam, which selective transmission enables the selective formation of surface textures or patterns and the development of porous structures. In an alternative embodiment the heating unit 5 could comprise a UN laser. Such a laser, in providing radiation having a shorter wavelength, provides for a smaller beam dimension.
The apparatus further comprises a material delivery unit 9 for delivering at least one precursor material to the deposition region such as to be irradiated by the radiation beam and transformed, in this embodiment following melting, to a solid material. By selectively metering the flow rate of precursor material to the deposition region in relation to the speed of travel of the substrate support 1, a deposit having a predetermined height can be developed. In this embodiment precursor material can be delivered at rates of up to about 5 gram per minute. In this embodiment the precursor material comprises one of fine, dry powder particles, typically having an average particle size of less than 20 μm, or a suspension of such fine powder particles in a liquid-containing carrier medium, in this embodiment a solvent, such as water or ethanol, which is evaporated by the heat of the radiation beam.
The material delivery unit 9 comprises at least one material reservoir 11 which contains a supply of precursor material, and a delivery channel 13 for delivering precursor material to the deposition region. The delivery channel 13 includes a nozzle head 15 at the distal end thereof for directing the delivery of precursor material. The nozzle head 15 has a small internal diameter, in this embodiment less than about 6 mm, and typically in the range of from about 3 mm to about 6 mm. In one embodiment the material delivery unit 9 includes a plurality of material reservoirs 11 such as to enable the selective delivery of ones of different precursor materials, and thereby enable the deposition of composite, functionally-graded or compositionally-graded materials.
The apparatus further comprises a material guiding unit for guiding the precursor material delivered from the nozzle head 15 of the delivery channel 13 of the material delivery unit 9 towards the deposition region. The material guiding unit comprises a high voltage supply 17 which is connected to the nozzle head 15 and the substrate support 1 such as to charge the powder particles of the precursor material, and an electromagnetic lens 19 for focusing the charged powder particles of the precursor material onto the deposition region. The electromagnetic lens 19 enables the lateral dimension of the deposit to be controlled as required.
The apparatus further comprises a reactive medium supply unit 20 for supplying a reactive medium, in this embodiment one or more gases, to the deposition region. The use of a reactive medium facilitates the interaction of the radiation beam and the powder of the precursor material.
The apparatus further comprises a control unit 21 for controlling the operation of the substrate support 1 such as to move the substrate 3 when depositing material and thereby form material deposits as required, the heating unit 5, the material supply unit 9 in delivering precursor material to the deposition region, the high voltage supply 17 and electromagnetic lens 19 of the material guiding unit in focusing the precursor material onto the deposition region, and the reactive medium supply unit 20.
In use, the substrate support 1 is moved under the control of the control unit 21 such as to expose deposition regions onto which material deposits are to be formed to the radiation beam, and, at the same time, precursor material is delivered by the material delivery unit 9 at a predetermined rate and focused by the material guiding unit onto the deposition region at or just ahead of the radiation beam. With this arrangement, by selectively controlling the travel of the substrate support 1, both in the x-y plane and z direction, the operation of the heating unit 5, the material delivery unit 9 and the material guiding unit, any form of material deposit can be achieved. In one mode of operation, a surface texture or pattern can be deposited by the selective formation of material deposits, for example, lines or beads of material having a predetermined pattern, with the selective deposition of material deposits being achieved by pulsing the radiation beam. In another mode of operation, a three-dimensional component can be fabricated by building up layers of material by the repeated scanning of the deposition surface, with the substrate support 1 being repeatedly lowered relative to the radiation beam for each layer such that the deposition surface is maintained at the focal point of the radiation beam. The structure of the material deposits is influenced by the particle size of the powder, the power of the heating unit 5, the dimension of the radiation beam, the travelling speed of the substrate support 1, and the rate of delivery of the precursor material.
Figure 2 illustrates a fabrication apparatus in accordance with a second embodiment of the present invention.
The fabrication apparatus of this embodiment is quite similar to the fabrication apparatus of the above-described embodiment, and thus, in order to avoid unnecessary duplication of description, only the differences will be described in detail.
The fabrication apparatus of this embodiment differs from that of the above-described embodiment in that the nozzle head 15 of the delivery channel 13 is co-axial with the radiation beam, whereby precursor material is delivered under the action of gravity to the o
deposition region in registration with the radiation beam, and in that the material guiding unit is omitted; this unit not being necessary since the delivery of precursor material is coincident with the radiation beam. In an alternative embodiment the material guiding unit could be incorporated. Operation is otherwise the same as for the above-described embodiment.
Figures 3 and 4 illustrate SEMs of material structures fabricated by the fabrication apparatus of this embodiment.
Figure 3 illustrates a cross-sectional view through a stainless steel line fabricated on a stainless steel plate. The stainless steel line was fabricated with the substrate support 1 at a travelling speed of 2 mm per second, with the stainless deposit having a height of about 100 μm and a width of about 250 μm and being bonded firmly to the stainless plate.
Figure 4 illustrates a plan view of a 3 mm x 3 mm stainless steel deposit pattern fabricated on a stainless steel plate. The pattern is bounded by a continuous stainless square which is defined by stainless lines, and includes two further squares therewithin which are defined by stainless beads, each having an average diameter of 250 μm. This configuration provides a graded porosity from the centre to the edge of the pattern.
Finally, it will be understood that the present invention has been described in its preferred embodiments and can be modified in many different ways without departing from the scope of the invention as defined by the appended claims.
For example, in one modification, the heating unit 5 can comprise an electron beam generator which provides an electron beam for heating the deposition region. REFERENCES
[1] D.L. Kendall, R.A. Shoultz, Handbook of Microhthography, Micromachining and Microfabrication (P. Rai-Choudhury), p 41, (1997).
[2] S.W. Pang, Handbook of Microhthography, Micromachining and Microfabrication (P. Rai Choudhury), p 99, (1997).
[3] C.R. Friedrich, R. Warrington, W. Bacher, W. Bauer, P.J. Coane, J. Gδttert, T. Hanemann, J. Hauβelt, M. Heckele, R. Knitter, J. Mohr, H-H. Ritzhaupt-Kleissl and R. Ruprecht, Handbook of Microhthography, Micromachining and Microfabrication (P. Rai-Choudhury), p 299, (1997).
[4] D.K. Stewart and J.D. Casey Jr., Handbook of Microhthography, Micromachining and Microfabrication (P. Rai-Choudhury), p 153, (1997).
[5] L.T. Romankiw and E.J.M. O'Sullivan, Handbook of Microhthography, Micromachining and Microfabrication (P. Rai-Choudhury), p 197, (1997).
[6] T. Grimm, Rapid News, Vol. 4(4), p 48, (1996).
[7] www.optomec.com.
[8] www.zcorp.com/flash/index.html.

Claims

1. A fabrication apparatus for fabricating material structures, comprising: a substrate support for supporting a substrate; a heating unit operable to provide a beam of radiation for heating a deposition region at the substrate and melting powder of a precursor material delivered thereto, which powder melt on cooling providing a solid material deposit, wherein the radiation beam is movable relative to the substrate support such as to enable the fabrication of a material structure by development of material deposits; a material delivery unit for delivering precursor material to the deposition region, the precursor material including a powder; and a material guiding unit for charging the powder of the precursor material and guiding the same in delivery to the deposition region.'
2. The apparatus of claim 1, wherein the material structure is a surface feature.
3. The apparatus of claim 2, wherein the surface feature is a pattern.
4. The apparatus of claim 2, wherein the surface feature is a texture.
5. The apparatus of any of claims 2 to 4, wherein the surface feature comprises a plurality of material deposits.
6. The apparatus of claim 1, wherein the material structure comprises a surface coating.
7. The apparatus of claim 6, wherein the surface coating is at least partially porous and comprises a plurality of material deposits.
8. The apparatus of claim 1, wherein the material structure comprises a three- dimensional component.
9. The apparatus of any of claims 1 to 8, wherein the material structure comprises a single layer.
10. The apparatus of any of claims 1 to 8, wherein the material structure comprises a plurality of layers.
11. The apparatus of claim 10, wherein the material structure is a compositionally- graded structure.
12. The apparatus of claim 10, wherein the material structure is a composite structure.
13. The apparatus of any of claims 1 to 12, wherein the powder has an average diameter of less than about 20 μm.
14. The apparatus of claim 13, wherein the powder has an average diameter of less than about 10 μm.
15. The apparatus of any of claims 1 to 14, wherein the precursor material comprises a powder contained in a fluid carrier medium.
16. The apparatus of claim 15, wherein the carrier medium comprises a liquid.
17. The apparatus of claim 15, wherein the carrier medium comprises a gel.
18. The apparatus of claim 15, wherein the carrier medium comprises a powder.
19. The apparatus of claim 15, wherein the carrier medium comprises a gas.
20. The apparatus of any of claims 15 to 19, wherein the carrier medium includes a reactive medium.
21. The apparatus of any of claims 15 to 20, wherein the carrier medium comprises a solvent.
22. The apparatus of any of claims 1 to 21, wherein the heating unit comprises a laser which is operable to provide a laser beam for heating the deposition region.
23. The apparatus of any of claims 1 to 21, wherein the heating unit comprises an electron beam generator which is operable to provide an electron beam for heating the deposition region.
24. The apparatus of any of claims 1 to 23, wherein the material delivery unit comprises at least one material reservoir for containing at least one precursor material, and a delivery channel for delivering the at least one precursor material towards the substrate.
25. The apparatus of claim 24, wherein the delivery channel includes a nozzle head having a delivery aperture for directing the precursor material.
26. The apparatus of claim 25, wherein the delivery aperture has a lateral dimension of not more than about 6 mm.
27. The apparatus of claim 26, wherein the delivery aperture has a lateral dimension of from about 3 mm to about 6 mm.
28. The apparatus of any of claims 25 to 27, wherein the delivery aperture is co-axial with the radiation beam.
29. The apparatus of any of claims 24 to 28, wherein the material delivery unit comprises a plurality of material reservoirs for containing different precursor materials, and the material delivery unit is operably configured selectively to deliver precursor material from one or more of the material reservoirs.
30. The apparatus of any of claims 1 to 29, wherein the material guiding unit comprises a high voltage supply for charging the powder of the precursor material and a field guiding element for guiding the powder of the precursor material in delivery to the deposition region.
31. The apparatus of claim 30, wherein the field guiding element comprises an electromagnetic lens.
32. The apparatus of any of claims 1 to 31, wherein the substrate support comprises a movable table.
33. The apparatus of any of claims 1 to 32, further comprising: a reactive medium supply unit for supplying a reactive medium to the deposition region.
34. The apparatus of claim 33, wherein the reactive medium comprises an aerosol.
35. The apparatus of claim 33, wherein the reactive medium comprises one or more gases.
36. A fabrication apparatus for fabricating material structures, comprising: a substrate support for supporting a substrate; a heating unit operable to provide a beam of radiation for heating a deposition region at the substrate and melting powder of a precursor material delivered thereto, which powder melt on cooling providing a solid material deposit, wherein the radiation beam is movable relative to the substrate support such as to enable the fabrication of a material structure by development of material deposits; and a material delivery unit for delivering precursor material to the deposition region, the precursor material comprising powder contained in a fluid carrier medium.
37. The apparatus of claim 36, wherein the material structure is a surface feature.
38. The apparatus of claim 37, wherein the surface feature is a pattern.
39. The apparatus of claim 37, wherein the surface feature is a texture.
40. The apparatus of any of claims 36 to 39, wherein the surface feature comprises a plurality of material deposits.
41. The apparatus of claim 36, wherein the material structure comprises a surface coating.
42. The apparatus of claim 41, wherein the surface coating is at least partially porous and comprises a plurality of material deposits.
43. The apparatus of claim 36, wherein the material structure comprises a three- dimensional component.
44. The apparatus of any of claims 36 to 43, wherein the material structure comprises a single layer.
45. The apparatus of any of claims 36 to 43, wherein the material structure comprises a plurality of layers.
46. The apparatus of claim 45, wherein the material structure is a compositionally- graded structure.
47. The apparatus of claim 45, wherein the material structure is a composite structure.
48. The apparatus of any of claims 36 to 47, wherein the powder has an average diameter of less than about 20 μm.
49. The apparatus of claim 48, wherein the powder has an average diameter of less than about 10 μm.
50. The apparatus of any of claims 36 to 49, wherein the carrier medium comprises a liquid.
51. The apparatus of any of claims 36 to 49, wherein the carrier medium comprises a gel.
52. The apparatus of any of claims 36 to 49, wherein the carrier medium comprises a powder.
53. The apparatus of any of claims 36 to 49, wherein the carrier medium comprises a gas.
54. The apparatus of any of claims 36 to 53, wherein the carrier medium includes a reactive medium.
55. The apparatus of any of claims 36 to 54, wherein the carrier medium comprises a solvent.
56. The apparatus of any of claims 36 to 55, wherein the heating unit comprises a laser which is operable to provide a laser beam for heating the deposition region.
57. The apparatus of any of claims 36 to 55, wherein the heating unit comprises an electron beam generator which is operable to provide an electron beam for heating the deposition region.
58. The apparatus of any of claims 36 to 57, wherein the material delivery unit comprises at least one material reservoir for containing at least one precursor material, and a delivery channel for delivering the at least one precursor material towards the substrate.
59. The apparatus of claim 58, wherein the delivery channel includes a nozzle head having a delivery aperture for directing the precursor material.
60. The apparatus of claim 59, wherein the delivery aperture has a lateral dimension of not more than about 6 mm.
61. The apparatus of claim 60, wherein the delivery aperture has a lateral dimension of from about 3 mm to about 6 mm.
62. The apparatus of any of claims 59 to 61, wherein the delivery aperture is co-axial with the radiation beam.
63. The apparatus of any of claims 36 to 62, wherein the material delivery unit comprises a plurality of material reservoirs for containing different precursor materials, and the material delivery unit is operably configured selectively to deliver precursor material from one or more of the material reservoirs.
64. The apparatus of any of claims 36 to 63, further comprising: a material guiding unit for charging the powder of the precursor material and guiding the same in delivery to the deposition region.
65. The apparatus of claim 64, wherein the material guiding unit comprises a high voltage supply for charging the powder of the precursor material and a field guiding element for guiding the powder of the precursor material in delivery to the deposition region.
66. The apparatus of claim 65, wherein the field guiding element comprises an electromagnetic lens.
67. The apparatus of any of claims 36 to 66, wherein the substrate support comprises a movable table.
68. The apparatus of any of claims 36 to 67, further comprising: a reactive medium supply unit for supplying a reactive medium to the deposition region.
69. The apparatus of claim 68, wherein the reactive medium comprises an aerosol.
70. The apparatus of claim 68, wherein the reactive medium comprises one or more gases.
71. A method of fabricating material structures, comprising the steps of: delivering a precursor material comprising a powder; charging the powder of the precursor material; guiding the charged powder of the precursor material to a deposition region at a substrate; heating the deposition region with a beam of radiation such as to melt powder of a precursor material delivered thereto, which powder melt when cooled provides a solid material deposit; and moving the substrate relative to the radiation beam such as to enable the fabrication of a material structure by development of material deposits.
72. The method of claim 71, wherein the material structure is a surface feature.
73. The method of claim 72, wherein the surface feature is a pattern.
74. The method of claim 72, wherein the surface feature is a texture.
75. The method of any of claims 72 to 74, wherein the surface feature comprises a plurality of material deposits.
76. The method of claim 71, wherein the material structure comprises a surface coating.
77. The method of claim 76, wherein the surface coating is at least partially porous and comprises a plurality of material deposits.
78. The method of claim 71, wherein the material structure comprises a three- dimensional component.
79. The method of any of claims 71 to 78, wherein the material structure comprises a single layer.
80. The method of any of claims 71 to 78, wherein the material structure comprises a plurality of layers .
81. The method of claim 80, wherein the material structure is a compositionally- graded structure.
82. The method of claim 80, wherein the material structure is a composite structure.
83. The method of any of claims 71 to 82, wherein the powder has an average diameter of less than about 20 μm.
84. The method of claim 83, wherein the powder has an average diameter of less than about 10 μm.
85. The method of any of claims 71 to 84, wherein the precursor material comprises a powder contained in a fluid carrier medium.
86. The method of claim 85, wherein the carrier medium comprises a liquid.
87. The method of claim 85, wherein the carrier medium comprises a gel.
88. The method of claim 85, wherein the carrier medium comprises a powder.
89. The method of claim 85, wherein the carrier medium comprises a gas.
90. The method of any of claims 85 to 89, wherein the carrier medium comprises a reactive medium.
91. The method of any of claims 85 to 90, wherein the carrier medium comprises a solvent.
92. The method of any of claims 71 to 91, wherein the radiation beam is a laser beam.
93. The method of any of claims 71 to 91, wherein the radiation beam is an electron beam.
94. The method of any of claims 71 to 93, wherein the step of delivering a precursor material comprises the step of: selectively delivering one or more precursor materials.
95. The method of any of claims 71 to 94, wherein the step of guiding the charged powder of the precursor material comprises the step of: applying a guiding field to guide the charged powder of the precursor material.
96. The method of claim 95, wherein the field is an electromagnetic field.
97. The method of any of claims 71 to 96, further comprising the step of: supplying a reactive medium to the deposition region.
98. The method of claim 97, wherein the reactive medium comprises an aerosol.
99. The method of claim 97, wherein the reactive medium comprises one or more gases.
100. A method of fabricating material structures, comprising the steps of: delivering a precursor material comprising a powder contained in a fluid carrier medium to a deposition region at a substrate; heating the deposition region with a beam of radiation such as to melt powder of a precursor material delivered thereto, which powder melt when cooled provides a solid material deposit; and moving the substrate relative to the radiation beam such as to enable the fabrication of a material structure by development of material deposits.
101. The method of claim 100, wherein the material structure is a surface feature.
102. The method of claim 101, wherein the surface feature is a pattern.
103. The method of claim 101, wherein the surface feature is a texture.
104. The method of any of claims 101 to 103, wherein the surface feature comprises a plurality of material deposits.
105. The method of claim 100, wherein the material structure comprises a surface coating.
106. The method of claim 105, wherein the surface coating is at least partially porous and comprises a plurality of material deposits.
107. The method of claim 100, wherein the structure comprises a three-dimensional component.
108. The method of any of claims 100 to 107, wherein the material structure comprises a single layer.
109. The method of any of claims 100 to 107, wherein the material structure comprises a plurality of layers.
110. The method of claim 109, wherein the material structure is a compositionally- graded structure.
111. The method of claim 109, wherein the material structure is a composite structure.
112. The method of any of claims 100 to 111, wherein the powder has an average diameter of less than about 20 μm.
113. The method of claim 112, wherein the powder has an average diameter of less than about 10 μm.
114. The method of any of claims 100 to 113, wherein the carrier medium comprises a liquid.
115. The method of any of claims 100 to 113, wherein the carrier medium comprises a gel.
116. The method of any of claims 100 to 113, wherein the carrier medium comprises a powder.
117. The method of any of claims 100 to 113, wherein the carrier medium comprises a gas.
118. The method of any of claims 100 to 117, wherein the carrier medium comprises a reactive medium.
119. The method of any of claims 100 to 118, wherein the carrier medium comprises a solvent.
120. The method of any of claims 100 to 119, wherein the radiation beam is a laser beam.
121. The method of any of claims 100 to 119, wherein the radiation beam is an electron beam.
122. The method of any of claims 100 to 121, wherein the step of delivering a precursor material comprises the step of: selectively delivering one or more precursor materials.
123. The method of any of claims 100 to 122, further comprising the steps of: charging the powder of the precursor material; and guiding the charged powder of the precursor material to a deposition region at a substrate.
124. The method of claim 123, wherein the step of guiding the charged powder of the precursor material comprises the step of: applying a guiding field to guide the charged powder of the precursor material.
125. The method of claim 124, wherein the field is an electromagnetic field.
126. The method of any of claims 100 to 125, further comprising the step of: supplying a reactive medium to the deposition region.
127. The method of claim 126, wherein the reactive medium comprises an aerosol.
128. The method of claim 127, wherein the reactive medium comprises one or more gases.
PCT/GB2001/005169 2000-11-23 2001-11-23 Fabrication apparatus and method WO2002042521A1 (en)

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