WO2007094973B1

WO2007094973B1 - Process for porous materials and property improvement methods for the same

Info

Publication number: WO2007094973B1
Application number: PCT/US2007/002763
Authority: WO
Inventors: Gunes M Ecer
Original assignee: Appliedus Corp; Gunes M Ecer
Priority date: 2006-02-09
Filing date: 2007-02-01
Publication date: 2008-02-14
Also published as: WO2007094973A2; US20060269434A1; EP1993759A2; WO2007094973A3

Abstract

A powder metallurgy method of forming a lightweight porous material body that includes mixing matrix material powder with one or more types of high volatility material powder having tendency to vaporize when heated to its vaporization temperature; hot consolidating the mixture under sufficient pressure and at a temperature below vaporization temperature of high volatility material powder to form a substantially consolidated body consisting of dispersions of high volatility material powder particles in the matrix material; heating the consolidated body to a temperature sufficient to vaporize the high volatility material powder particles and to create a vapor pressure sufficiently high to cause yielding of surrounding matrix material, thus forming pores, cooling the compact body after pore formation.

Claims

49AMENDED CLAIMS received by the International Bureau on 13 Dec2007 (13.12.2007)

1. A powder metallurgy method of forming a lightweight porous material body, comprising: a) mixing matrix material powder with one or more types of high volatility material powder having tendency to vaporize when heated to its vaporization temperature, b) hot consolidating the mixture under sufficient pressure and at a temperature below vaporization temperature of high volatility material powder to form a substantially consolidated body consisting of dispersions of high volatility material powder particles in said matrix material, said hot consolidating effected to form said body into at least 90% dense state, c) heating said consolidated body to a temperature sufficient to vaporize said high volatility material powder particles and to create a vapor pressure sufficiently high to cause yielding of surrounding matrix material, thus forming pores, d) cooling said compact body after pore formation, said cooling effected without prior sintering of the body.

2. The method of claim 1 wherein said consolidated body is heated in step (c) to a pore forming temperature below the solidus temperature of matrix material for better control of pore size and size distribution.

3. The method of claim 1 wherein said consolidated body is heated in step (c) to a pore forming temperature below the Uquidus temperature of matrix materia?.

4. The method of claim 1 wherein said consolidated body is heated in ste.p (c) to a pore forming temperature above the liquidus temperature of matrix material.

5. The method of claim 1 wherein said high volatility material is selected from a group of compounds including common elements, oxides, fluorides, borides, carbonates, carbides, hydrides, and chlorides of elements.

6. The method of claim 1 wherein said consolidation takes place isothermally.

7. The method of claim 1 wherein said consolidation fakes place under a protective atmosphere, including partial vacuum.

8. The method of claim 1 wherein said consolidated body is placed in step (c) in a cavity die to restrict its growth due to pore formation, in at least one direction.

9. The method of claim 1 wherein said consolidated body is deformation processed for easy conversion to typical industrial material forms, including bar stock, plate, sheet, foil, wire, forging stock, and rolled or extruded material shapes, prior to carrying out 50

step (c).

10. The method of claim 1 wherein said consolidation in step (b) produces a net or near net shaped product prior to forming pores in step (c).

11. The method of claim 1 wherein said high volatility material particles release thermally stable compound forming vapors upon heating to pore forming temperature; forming stable compounds including oxides, borides, nitrides, carbides with one or more elemental ingredients of said matrix metal on or near pore surfaces; covering said surfaces at least in part; said stable compound covered pores strengthening said matrix metal.

12. The method of claim 11 wherein average separation distance between said stable compound formed pores is less than 10 micro-meters.

13. The method of claim 11 wherein average diameter of said stable compound covered pores is less than 100 micro-meters.

14. The method of claim 1 wherein said powder mixture is placed at least at one surface next to another powder mass devoid of high volatility material powder, prior to consolidation; consolidation causing bonding of said adjoined powder masses.

15. The method of claim 1 wherein said powder mixture is placed at least at one surface next to a rigid material mass devoid of high volatility material, prior to consolidation; consolidation causing bonding of said mixture and said rigid material;

16. The method of claim 1 wherein said consolidated body has a density higher than 90% of its theoretical density.

17. A deposition method of forming a lightweight porous metal body, comprising: a) dispersing one or more types of high volatility material powder within a matrix metal being deposited onto a base material; high volatility material powder having tendency to vaporize when heated to its vaporization temperature to create a deposited body made of matrix material, wherein high volatility powder is distributed, and hot pressing said deposited body at a temperature below pore forming temperature of high volatility metal powder and under sufficient pressure to consolidate matrix metal powder to density near at least 90% of its maximum theoretical density, b) heating said deposited body to a pore forming temperature sufficient to vaporize said high volatility material powder particles and to create a vapor pressure sufficiently high to cause yielding of surrounding matrix metal, and thus forming pores within said matrix metal. 51

18. The method of claim 17 wherein said deposited body is heated in step (b) to a pore forming temperature below the solidus temperature of matrix metal, forming pores within said matrix metal.

19. The method of claim 17 wherein said deposition method includes the methods of plating, vapor deposition, plasma spraying, molten droplet spraying.

20. The method of claim 17 wherein said high volatility material is selected from a group of compounds including common elements, oxides, fluorides, borides, carbonates, carbides, hydrides, and chlorides of elements.

21. The method of claim 17 wherein said deposited body is placed in step (b) in a cavity die to restrict its growth due to pore formation, in at least one direction.

22. The method of claim 17 wherein said deposited body is deformation processed for conversion to typical industrial metal forms, including bar stock, plate, sheet, foil, wire, forging stock, and rolled or extruded metal shapes, prior to carrying out step (b).

23. The method of claim 17 wherein said deposited metal bonds to said base material producing a bi-material as semi finished product.

24. The method of claim 17 wherein said base material is disposable.

25. The method of claim 17 wherein said high volatility material particles release thermally stable compound forming vapors upon heating to pore forming temperature, forming stable compounds including oxides, borides, nitrides, and carbides with one or more elemental ingredients of said matrix metal on or near pore surfaces, covering said surfaces at least in part; said stable compound covered pores strengthening said matrix metal.

26. The method of claim 25 wherein mean separation distance between said stable pores is less than 10 micro-meters.

27. The method of claim 25 wherein average diameter of said stable compound covered pores is less than 100 micro-meters.

28. A process of manufacturing objects containing at least one pore, the process comprising the steps of: a) distributing at least one high volatility material powder particle within a substantially dense matrix material to create a composite, and hot pressing said composite under sufficient pressure and at a temperature below pore forming temperature of high volatility metal powder to compact matrix metal powder to at least 90% of its maximum theoretical density, b) heating said composite to a pore formation temperature, at which vapor 52

pressure of said high volatility material is higher than the yield strength of said matrix material, wherein said high volatility material particle evaporates to form at least one cavity pore within said matrix material.

29. The process of claim 28 wherein said distributing involves one of the following methods modified to introduce particles of high volatility material in said matrix material: consolidation of powder mixture under pressure, electrolytic plating, electroless plating, vapor deposition, molten droplet deposition, plasma coating, plasma spraying, high- energy forming methods, roll forming, extruding, plastic forming methods, slurry mixing and drying, sintering of dried ceramic slips and slurries, melting, and other similar methods.

30. The process of claim 28 wherein said high volatility material is selected from elements from the periodic table, oxides, carbides, nitrides, chlorides, bromides, sulfides, fluorides, carbonates, and hydrides of elements.

31. The process of claim 28 wherein said composite is placed inside a shaped mold before step (b); said shaped mold defining, at least in part, the exterior shape of said matrix material after step (b).

32. The process of claim 28 wherein said high volatility materia) particle consists of more than one powder particle pre-formed into a shape to promote shaped cavities within said matrix material.

33. The process of claim 28 wherein chemistry of at least some of said high volatility material particles differ from each other.

34. The process of claim 28 wherein at least some of said high volatility material particles evaporate and react with pore walls of said matrix material to form at least one type of thermally stable compound at said pore forming temperature, thermally stable compound formation strengthening said matrix material.

35. The process of claim 28 wherein at least some of said particles are distributed in a pre-determined pattern, in selected location within said matrix material.

36. The process of claim 28 wherein said high volatility material particles are placed in close proximity of each other, said pores forming in close proximity and joining to form a continuous cavity within said matrix material when heated to pore formation temperature.

37. The process of claim 28 wherein size, shape, and relative position of said pore cavity within said matrix material would be determined by any combination of the basic process control variables, variables including pore formation temperature, type, size, amount, shape, and particle distribution pattern of high volatility material, mold dimensions and shape, matrix powder particle size and shape, and other factors, including time at pore forming temperature, changes in pore forming temperature, cooling and heating rate and direction, usage of more than one type of high volatility material.

38. The process of claim 28 wherein said composite contains particles of at least two types of high volatility material powder wherein at Jeast one type of said high volatility material particles release thermally stable compound forming vapors upon heating to pore forming temperature, said vapors forming stable compounds including oxides, borides, nitrides, and carbides with one or more elemental ingredients of said matrix metal on or near pore surfaces covering said surfaces at least in part, said stable compound covered pores strengthening said matrix metal.

39. Products produced according to claims 1, or 17, or 28.

40. Products produced according to claims 1 , 17, or 28, wherein at least some of said pores are interconnecting.

41. A process according to claims 1, 17, or 28, wherein said pore size is controlled by a combination of processing variables, including pore forming temperature and time at pore forming temperature, high volatility material type and particle size, and confinement of said matrix material, at least in one direction, to a pre-determined volume during pore formation.

42. The process of claim 41 wherein said matrix material is a brittle material including a ceramic, a glass, or a brittle metal, wherein presence of said pores improves ductility of said matrix material.

43. A process according to claims 1 or 28. wherein said matrix material is a transparent material, including some plastics and glasses wherein size of said pores is controlled to impart desired radiation energy transmission, absorption, reflection properties to said transparent material.

44. Products produced by a method according to claims 1, 17, or 28, wherein the product has one or more of desirable engineering characteristics, including high energy absorption properties, sound absorption properties, low thermal conductivity properties. and large surface area per unit volume.

45. A process according to claims 1 , 17, or 28, wherein said matrix material is selected from one of the groups of materials including metals, semi-metals, metal alloys, plastics, glasses, ceramics, and any combination of these materials. 54

46. The method of claim 17 wherein said dispersing and heating steps are controlled to produced pore sizes Io be less than 100 microns.

47. The method of claim 17 wherein said dispersing and heating steps are controlled to produce average pore spacing to be less than 10 micrometers.

48. The method of claim 17 wherein said dispersing and heating steps are controlled to produce average pore spacing Io be less than 3 micrometers.