Claims
- 1. A method of forming a deposit on the surface of a substrate comprising the steps of:
- teeming a stream of molten metal, metal alloy or molten ceramic through an atomizing device;
- generating a spray of gas atomized molten metal, metal alloy or molten ceramic particles by the application of an atomizing gas at a temperature less than that of said molten metal, metal alloy or molten ceramic, said spray having a mean axis directed at the substrate,
- rotating the substrate about an axis of the substrate, and
- extracting heat in flight and/or on deposition from the atomized particles by said cooler atomizing gas to produce a coherent deposit,
- the improvement comprising:
- (i) oscillating the spray in the direction of the axis of the substrate whereby:
- (a) the angle of the mean axis of the spray to the substrate and to the molten stream is varied, and
- (b) the deposition profile of the spray is modified by elongation along the length of the substrate;
- (ii) oscillating the spray at a speed of oscillation sufficiently rapid that a thin layer of semi-solid/semi-liquid metal or ceramic is substantially maintained at the surface of the deposit over the amplitude of oscillation into which further particles are deposited to maintain a substantially uniform microstructure through the thickness of the deposit; and
- (iii) moving the substrate in axial direction during deposition of the atomized particles onto the substrate by an amount greater than the amplitude of oscillation whereby a deposit of continuous or semi-continuous length is formed.
- 2. A method of forming a deposit on the surface of an elongated substrate comprising the steps of:
- teeming a stream of molten metal, metal alloy or molten ceramic through an atomizing device;
- generating a spray of gas atomized molten metal, metal alloy or ceramic particles by means of an atomizing device with a relatively cold atomizing gas, the spray having a mean axis directed at the substrate and the substrate being positioned with its longitudinal axis transverse to the spray,
- supporting the atomizing device for angular movement about an axis transverse to the mean axis of the spray, rotating the substrate about its longitudinal axis, effecting angular movement of the atomizing device whereby: the spray is oscillated, and the angle of the mean axis of the spray relative to the substrate and to the molten stream is varied so that the spray is moved over at least part of the surface of the substrate, and the deposition profile of the spray is modified by elongation along the length of the substrate, extracting a controlled amount of heat in flight and on deposition from the atomized particles by the relatively cold atomizing gas to produce and maintain a thin layer of semi-solid/semi-liquid metal or ceramic at the deposition surface over the amplitude of the oscillation throughout the deposition operation into which further particles are deposited to produce a deposit which has a non-particulate microstructure and is free from macro-segregation; and moving the substrate in axial direction during deposition of the atomized particles onto the substrate by an amount greater than the amplitude of oscillation so that a deposit of continuous or semi-continuous length is formed.
- 3. A method according to claim 1 wherein the substrate is additionally moved in its axial direction relative to the spray.
- 4. A method according to claim 1 wherein the axis of the substrate is substantially perpendicular to the direction of the mean axis of the spray during a part of its oscillation.
- 5. A method according to claim 2 wherein the spray is oscillating along at least a part of the length of the substrate.
- 6. A method according to claim 1 wherein the speed of movement of the spray is varied during each cycle of oscillation.
- 7. A method according to claim 1 wherein the gas to metal mass ratio is varied from cycle to cycle or during each cycle of oscillation in order to accurately control the deposition conditions of the atomized particles deposited on different parts of the substrate.
- 8. A method according to claim 1 wherein the substrate is a collector and the deposit formed is a hollow body generated about the axis of rotation.
- 9. A method according to claim 1 wherein the deposit is a discrete deposit and a variable amount of heat is extracted in flight during the formation of the deposit to maintain said thin layer.
- 10. A method according to claim 9 wherein less heat is extracted in flight on initial deposition to reduce porosity.
- 11. A method according to claim 9 wherein the extraction of heat is varied during each cycle of oscillation as well as from cycle to cycle.
- 12. A method according to claim 1 comprising the additional step of introducing ceramic or metal particles or fibers into the deposit.
- 13. A method according to claim 1 wherein the speed of rotation of the substrate is varied.
- 14. A method according to claim 1 wherein the speed of rotation of the substrate and the speed of oscillation are interrelated to form a predetermined pattern of deposition.
- 15. A method according to claim 1 wherein metallic or non-metallic particles and/or fibers are introduced into the atomized spray to form a composite deposit.
- 16. A method according to claim 15 wherein a graded microstructure is produced by varying the amount of particles and/or fibers throughout the deposition cycle.
- 17. A method according to claim 1 comprising generating a spray of gas atomized molten metal alloy particles and varying the alloy composition throughout the deposition cycle to produce a graded microstructure.
- 18. A method of forming a deposit on the surface of a substrate comprising the steps of:
- teeming a stream of molten metal, metal alloy or molten ceramic through an atomizing device;
- generating a spray of gas atomized molten metal, metal alloy or molten ceramic particles by the application of an atomizing gas at a temperature less than that of said molten metal, molten alloy or molten ceramic, said spray having a mean axis directed at the substrate,
- rotating the substrate about an axis of the substrate, extracting heat in flight and/or on deposition from the atomized particles by said cooler atomizing gas to produce a deposit, and moving the substrate relative to the spray in a single pass, the improvement comprising oscillating the spray in the direction of the axis of the substrate whereby the angle of the main axis of the spray to the substrate and to the molten stream is varied so that the spray is moved over at least a part of the surface of the substrate,
- controlling the rate of speed of the oscillation so that it is sufficiently fast to maintain a thin layer of semi-solid/semi-liquid metal or ceramic at the surface of the deposit over the amplitude of oscillation into which further particles are deposited, and controlling the rate and amplitude of the oscillation of the spray to favorably influence the angle of impingement of the atomized particles on the forming deposit and to modify the deposition profile of the spray by elongation along the length of the substrate.
- 19. A method according to claim 1 wherein the speed of oscillation is between five and 30 cycles per second.
Priority Claims (2)
Number |
Date |
Country |
Kind |
8527853 |
Nov 1985 |
GBX |
|
8527854 |
Nov 1985 |
GBX |
|
Parent Case Info
This is a continuation of application Ser. No. 07/323,158 filed on Mar. 15, 1989, now abandoned, which is a continuation of application Ser. No. 07/083,788 filed on Jul. 1, 1987, now abandoned.
US Referenced Citations (11)
Foreign Referenced Citations (4)
Number |
Date |
Country |
2043882 |
Feb 1974 |
DEX |
1379261 |
Jan 1975 |
GBX |
1472939 |
May 1977 |
GBX |
1599392 |
Sep 1981 |
GBX |
Continuations (2)
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Number |
Date |
Country |
Parent |
323158 |
Mar 1989 |
|
Parent |
83788 |
Jul 1987 |
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