Method of Making Porous Metal Articles

• US 20120065739A1
• Filed: 10/11/2011
• Published: 03/15/2012
• Est. Priority Date: 07/02/2004
• Status: Active Grant

• Current Assignee: Praxis Powder Technology, Inc.
• Original Assignee: Praxis Powder Technology, Inc.
• Inventors: Grohowski, Joseph A. Jr.
• Granted Patent: US 9,089,427 B2
• Time in Patent Office: Days
• US Class Current: 623/23.53
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/30771 applied in original prostheses, e.g. holes or grooves
• CPC Class Codes: A61F 2/3094 Designing or manufacturing processes
• CPC Class Codes: A61F 2/32 for the hip
• CPC Class Codes: A61F 2/34 Acetabular cups
• CPC Class Codes: A61F 2/36 Femoral heads ; Femoral endoprostheses
• CPC Class Codes: A61F 2/3662 Femoral shafts
• CPC Class Codes: A61F 2002/30011 differing in porosity
• CPC Class Codes: A61F 2002/30929 having at least two superposed coatings
• CPC Class Codes: A61F 2002/30957 using a positive or a negative model, e.g. moulds
• CPC Class Codes: A61F 2002/30968 Sintering
• CPC Class Codes: A61F 2250/0023 differing in porosity
• CPC Class Codes: A61F 2310/00017 Iron- or Fe-based alloys, e.g. stainless steel
• CPC Class Codes: A61F 2310/00023 Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00029 Cobalt-based alloys, e.g. Co-Cr alloys or Vitallium
• CPC Class Codes: A61F 2310/00047 Aluminium or Al-based alloys
• CPC Class Codes: A61F 2310/00071 Nickel or Ni-based alloys
• CPC Class Codes: A61F 2310/00077 Copper or Cu-based alloys
• CPC Class Codes: A61F 2310/00095 Niobium or Nb-based alloys
• CPC Class Codes: A61F 2310/00131 Tantalum or Ta-based alloys
• CPC Class Codes: A61L 2430/02 : for reconstruction of bones; weight-bearing implants
• CPC Class Codes: A61L 27/04 : Metals or alloys
• CPC Class Codes: A61L 27/427 : of other specific inorganic materials not covered by A61L27/422 or A61L27/425
• CPC Class Codes: A61L 27/56 : Porous materials, e.g. foams or sponges
• CPC Class Codes: B01D 2239/10 : Filtering material manufacturing
• CPC Class Codes: B01D 39/2093 : Ceramic foam
• CPC Class Codes: B22F 1/00 : Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
• CPC Class Codes: B22F 1/103 : containing an organic binding agent comprising a mixture of, or obtained by reaction of, two or more components other than a solvent or a lubricating agent
• CPC Class Codes: B22F 2301/052 : Aluminium
• CPC Class Codes: B22F 2301/15 : Nickel or cobalt
• CPC Class Codes: B22F 2301/20 : Refractory metals
• CPC Class Codes: B22F 2301/35 : Iron
• CPC Class Codes: B22F 2998/00 : Supplementary information concerning processes or compositions relating to powder metallurgy
• CPC Class Codes: B22F 2999/00 : Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B22F 3/02 : Compacting only
• CPC Class Codes: B22F 3/1109 : Inhomogenous pore distribution composite layers of porous nature B22F7/002
• CPC Class Codes: B22F 3/1121 : by using decomposable, meltable or sublimatable fillers
• CPC Class Codes: B22F 3/20 : by extruding
• CPC Class Codes: B22F 3/22 : for producing castings from a slip
• CPC Class Codes: B22F 3/225 : by injection molding
• CPC Class Codes: B29C 43/006 : Pressing and sintering powders, granules or fibres
• CPC Class Codes: B29L 2031/7532 : Artificial members, protheses

Abstract

In one embodiment, the present invention may be a method of making a porous biocompatible metal article by combining a metal powder with a homogenizing aid to form metal granules, including blending the metal granules and an extractable particulate to form a composite, forming the composite into a green article, removing the extractable particulate from the green article to form a metal matrix and pore structure, and sintering the metal matrix and pore structure. Furthermore the present invention may include a second homogenizing aid combined with the extractable particulate. The present invention also includes shaping the metal matrix and pore structure with or without the use of a binder.

Claims

1. A method of making a porous biocompatible metal article, the method comprising:

a. combining a metal powder with a first homogenizing aid to form metal granules;

b. blending the metal granules and an extractable particulate to form a composite;

c. forming the composite into a green article;

d. removing the extractable particulate from the green article to form a metal matrix and pore structure; and

e. sintering the metal matrix and pore structure.

2. The method of claim 1, further comprising combining the extractable particulate with a second homogenizing aid.

3. The method of claim 1, wherein the first homogenizing aid is selected from the group consisting of polyethylene glycol, polyethylene wax, polypropylene wax, poly(2-ethyl-2-oxazoline), methylcellulose, agar, polyvinylpyrrolidone, polyvinyl alcohol, hydroxypropylmethylcellulose, and gelatin based materials.

4. The method of claim 3, wherein the first homogenizing aid is polyethylene glycol having a molecular weight of approximately 2000 to 35000.

5. The method of claim 3, wherein the first homogenizing aid is solid at room temperature.

6. The method of claim 2, wherein the second homogenizing aid is selected from the group consisting of mineral oil or polyethylene glycol.

7. The method of claim 6, wherein the second homogenizing aid is polyethylene glycol having a molecular weight in the range of 150 to 800.

8. The method of claim 1, wherein the metal powder is selected from the group consisting of:

titanium, tantalum, cobalt chrome, niobium, stainless steel, nickel, copper, aluminum, and alloys thereof.

9. The method of claim 1, further comprising the step of sieving the metal granules to a size below 48 mesh.

10. The method of claim 9, wherein the sieving is to below 70 mesh.

11. The method of claim 1, wherein the extractable particulate is selected from the group consisting of:

salts, carbonates and sorbates.

12. The method of claim 11, wherein the extractable particulate has a diameter between about 50 and 1000 microns.

13. The method of claim 1, wherein the green article is formed by one of slip casting, compaction, compression, extrusion, or injection molding.

14. The method of claim 1, wherein the extractable particulate is removed by dissolving the extractable particulates in a fluid.

15. The method of claim 14, wherein the fluid is one of water or gas.

16. The method of claim 13, wherein the compaction deforms the metal powder and provides a shape to the metal matrix and pore structure.

17. The method of claim 1, wherein the first homogenizing aid provides a shape to the metal matrix and pore structure by binding the metal powder.

18. The method of claim 1, wherein the porous metal article is an orthopedic implant.

19. A method of making a porous metal article, the method comprising:

a. combining a metal powder with a first homogenizing aid to form metal granules;

b. blending the metal granules and an extractable particulate to form a composite;

c. forming the composite into a green article;

d. sintering the green article.

20. The method of claim 19 further comprising removing the first homogenizing aid and the extractable particulate to form a metal matrix and pore structure.

21. An orthopedic implant comprising the metal matrix and pore structure according to claim 20.

22. The orthopedic implant of claim 21 wherein the metal matrix and pore structure is suitable for bone ingrowth.

23. The orthopedic implant of claim 21 being an implantable device.

24. The method of claim 19, wherein the metal powder is selected from the group consisting of commercially pure titanium and titanium alloys.

25. The method of claim 24, wherein the metal powder is between approximately 1 micron and 150 microns.

26. The method of claim 25 wherein the first homogenizing aid is selected from the group consisting of polyethylene glycol, polyethylene wax, polypropylene wax, poly(2-ethyl-2-oxazoline), methylcellulose, agar, polyvinylpyrrolidone, polyvinyl alcohol, hydroxypropylmethylcellulose, and gelatin based materials.

27. The method of claim 26 wherein combining of the metal powder comprises

a. emulsifying the first homogenizing aid in water to form an emulsion;

b. spraying the emulsion onto a fluidized bed of the metal powder to form the metal granules; and

c. drying the metal granules at between approximately 30 and 80 degrees Celsius.

28. The method of claim 27 further comprising sieving the granules to −

70 mesh.

29. The method of claim 28 wherein the extractable particulate is spherical potassium chloride having an average diameter of 50-600 microns.

30. The method of claim 29 wherein the extractable particulate is coated with a second homogenizing aid.

31. The method of claim 30 wherein the second homogenizing aid is polyethylene glycol having a molecular weight of approximately 200.

32. The method of claim 31 wherein the forming comprising subjecting the composite to a pressure so as to deform the metal particles.

33. The method of claim 32 further comprising removing the first and second homogenizing aids through dissolution in water.

34. The method of claim 31 wherein the forming comprises subjecting the composite to a pressure of less than 20,000 pounds-per-square inch.

35. The method of claim 34 further comprising removing the second homogenizing aid through dissolution in water.

36. The method of claim 19 further comprising combining the green article with a substrate.

37. The method of claim 26 wherein combining of the metal powder comprises

a. dissolving the first homogenizing aid in water to form a solution;

b. spraying the solution onto a fluidized bed of the metal powder to form the metal granules; and

c. drying the metal granules at between approximately 30 and 80 degrees Celsius.

38. A method of making a porous metal article, the method comprising:

a. emulsifying a first homogenizing aid in water to form an emulsion;

b. spraying the emulsion onto a fluidized bed of a metal powder to form metal granules, wherein the first homogenizing aid is a water insoluble organic material, and the metal powder is selected from the group consisting of commercially pure titanium powder and titanium alloy powder between approximately 1 micron and 150 microns;

c. drying the metal granules at between approximately 30 and 80 degrees Celsius;

d. sieving the granules to −

70 mesh;

e. combining an extractable particulate with a second homogenizing aid, wherein the extractable particulate is spherical potassium chloride having an average diameter of 50-600 microns, and wherein the second homogenizing aid is polyethylene glycol having a molecular weight of approximately 200;

f. blending the metal granules and the extractable particulate to form a composite;

g. shaping the composite to form a green article by applying a pressure of less than 15,000 pounds-per-square inch to the composite;

h. removing the extractable particulate and the second homogenizing aid through dissolution in water to form a metal matrix and pore structure, wherein the first homogenizing aid provides a shape to the metal matrix and pore structure by binding the metal powder;

i. removing the first homogenizing aid by heating the metal matrix and pore structure; and

j. sintering the metal matrix and pore structure.