Laser-produced porous surface

• US 7,537,664 B2
• Filed: 11/07/2003
• Issued: 05/26/2009
• Est. Priority Date: 11/08/2002
• Status: Active Grant

• Current Assignee: University of Liverpool
• Original Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Inventors: Sutcliffe, Christopher J., Jones, Eric, O'Neill, William
• Primary Examiner(s): King; Roy
• Assistant Examiner(s): Velasquez; Vanessa
• Application Number:
  US10/704,270
• Publication Number:
  US 20040191106A1
• Time in Patent Office: 2,027 Days
• Field of Search: 419/2, 419/1, 419/47, 753/00, 752/28, 752/45, 752/46, 757/46, 757/51, 75755-759, 757/65, 757/70, 148/95, 148/512, 148/513, 148/516, 148/522, 148/524, 148/525, 148/527, 148/529, 148/559, 148/565, 148/579, 148/688, 148/714
• US Class Current: 148/525
• 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 2/30907 Nets or sleeves applied to surface of prostheses or in cement
• CPC Class Codes: A61F 2/3094 Designing or manufacturing processes
• CPC Class Codes: A61F 2/30965 Reinforcing the prosthesis by embedding particles or fibres during moulding or dipping
• CPC Class Codes: A61F 2/34 Acetabular cups
• CPC Class Codes: A61F 2/3662 Femoral shafts
• CPC Class Codes: A61F 2/3859 Femoral components
• CPC Class Codes: A61F 2/389 Tibial components A61F2/3868 takes precedence
• CPC Class Codes: A61F 2002/30006 differing in density or specific weight
• CPC Class Codes: A61F 2002/30011 differing in porosity
• CPC Class Codes: A61F 2002/30153 rectangular
• CPC Class Codes: A61F 2002/30199 Three-dimensional shapes
• CPC Class Codes: A61F 2002/30261 parallelepipedal
• CPC Class Codes: A61F 2002/30915 made of a stack of bonded perforated sheets, grids or wire meshes
• CPC Class Codes: A61F 2002/3092 having an open-celled or open-pored structure
• CPC Class Codes: A61F 2002/30929 having at least two superposed coatings
• CPC Class Codes: A61F 2002/3093 for promoting ingrowth of bone tissue
• CPC Class Codes: A61F 2002/30968 Sintering
• CPC Class Codes: A61F 2002/3097 using laser
• CPC Class Codes: A61F 2002/30971 : Laminates, i.e. layered products
• CPC Class Codes: A61F 2230/0019 : rectangular
• CPC Class Codes: A61F 2230/0063 : Three-dimensional shapes
• CPC Class Codes: A61F 2230/0082 : parallelepipedal
• CPC Class Codes: A61F 2250/0015 : differing in density or specific weight
• 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 2310/00095 : Niobium or Nb-based alloys
• CPC Class Codes: A61F 2310/00131 : Tantalum or Ta-based alloys
• CPC Class Codes: A61F 2310/00401 : Coating made of iron, of stainless steel or of other Fe-based alloys
• CPC Class Codes: A61F 2310/00407 : Coating made of titanium or of Ti-based alloys
• CPC Class Codes: A61F 2310/00413 : Coating made of cobalt or of Co-based alloys
• CPC Class Codes: A61F 2310/00491 : Coating made of niobium or Nb-based alloys
• CPC Class Codes: A61F 2310/00544 : Coating made of tantalum or Ta-based alloys
• CPC Class Codes: B22F 10/28 : Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
• CPC Class Codes: B22F 10/36 : of energy beam parameters
• CPC Class Codes: B22F 10/366 : Scanning parameters, e.g. hatch distance or scanning strategy
• CPC Class Codes: B22F 10/37 : of powder bed aspects, e.g. density
• CPC Class Codes: B22F 10/38 : to achieve specific product aspects, e.g. surface smoothness, density, porosity or hollow structures
• CPC Class Codes: B22F 10/80 : Data acquisition or data processing
• CPC Class Codes: B22F 2301/15 : Nickel or cobalt
• CPC Class Codes: B22F 2301/20 : Refractory metals
• CPC Class Codes: B22F 2301/205 : Titanium, zirconium or hafnium
• CPC Class Codes: B22F 2301/35 : Iron
• CPC Class Codes: B22F 2999/00 : Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B22F 3/1103 : with particular physical characteristics
• CPC Class Codes: B22F 3/1115 : comprising complex forms, e.g. honeycombs
• CPC Class Codes: B22F 7/004 : comprising at least one non-porous part
• CPC Class Codes: B23K 2101/35 : Surface treated articles
• CPC Class Codes: B23K 2103/05 : Stainless steel
• CPC Class Codes: B23K 2103/08 : Non-ferrous metals or alloys
• CPC Class Codes: B23K 2103/14 : Titanium or alloys thereof
• CPC Class Codes: B23K 2103/26 : Alloys of Nickel and Cobalt and Chromium
• CPC Class Codes: B23K 2103/50 : Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 26/382 : by boring
• CPC Class Codes: B23K 26/40 : taking account of the properties of the material involved
• CPC Class Codes: B29C 64/153 : using layers of powder being selectively joined, e.g. by selective laser sintering or melting
• CPC Class Codes: B33Y 10/00 : Processes of additive manufacturing
• CPC Class Codes: B33Y 70/00 : Materials specially adapted for additive manufacturing
• CPC Class Codes: B33Y 80/00 : Products made by additive manufacturing
• CPC Class Codes: C23C 24/04 : Impact or kinetic deposition of particles
• CPC Class Codes: C23C 24/10 : with intermediate formation of a liquid phase in the layer
• CPC Class Codes: C23C 26/02 : applying molten material to the substrate
• CPC Class Codes: C23C 4/02 : Pretreatment of the material to be coated, e.g. for coating on selected surface areas
• CPC Class Codes: C23C 4/12 : characterised by the method of spraying
• CPC Class Codes: C23C 4/18 : After-treatment
• CPC Class Codes: Y02P 10/25 : Process efficiency

Abstract

A method of fabricating a porous or partially porous three-dimensional metal article for use as a tissue ingrowth surface on a prosthesis. The porous article is formed using direct laser remelting in a cross section of a layer of metallic powder on a build platform without fusing thereto. The power, speed, spot size and beam overlap of the scanning laser is coordinated so that a predetermined porosity of the metallic powder can be achieved. Laser factors also vary depending from the thickness of the powder layer, type of metallic powder and size and size distribution of the powder particles. Successive depositing and remelting of individual layers are repeated until the article is fully formed by a layer-by-layer fashion. In an additional embodiment, a first layer of metallic powder may be deposited on a solid base or core and fused thereto.

Claims

1. A method of producing a three-dimensional porous tissue ingrowth structure comprising:

depositing a first layer of a powder made from a metal selected from the group consisting of titanium, titanium alloys, stainless steel, cobalt chrome alloys, tantalum and niobium, onto a substrate;

scanning a laser beam at least once over said first layer of metal powder to remelt the metal powder in order to create at least two solid lines, said laser beam having a power (P) in Joule per sec. with a scanning speed (v) in millimeters per sec., and a line separation (d) in millimeters such that the number calculated by the formula P/(d×

v) lies between the range 0.3-8 J/mm², so as to give a required pore size;

depositing at least one layer of said powder onto said first layer; and

repeating said laser scanning steps for each successive layer until a desired height is reached.

2. The method according to claim 1, wherein during said step of repeating said laser scanning steps, at least one laser scan is carried out angled relative to another laser scan in order to develop an interconnecting or non-interconnecting porosity.

3. The method according to claim 1, wherein the thickness of each of said first layer and said successive layers of powder is between 5 μ

m-2000 μ

m.

4. The method according to claim 1, wherein said substrate is a base or core made of a metal selected from the group consisting of titanium, titanium alloys, stainless steel, cobalt chrome alloys, tantalum and niobium, wherein said first layer is fused to said base or core.

5. The method according to claim 1, wherein said laser power may be varied within a range between 5 to 1000 watts.

6. The method according to claim 1, wherein said laser power is applied continuously.

7. The method according to claim 1, wherein said laser power is applied in a pulsed manner.

8. The method according to claim 7, wherein said pulse has a repetition rate between approximately 1 KHz to 50 KHz.

9. The method according to claim 1, wherein the method is carried out under an inert atmosphere.

10. The method according to claim 9, wherein the method is carried out under an Argon inert atmosphere.

11. The method according to claim 4, wherein said first layer is a cobalt chrome alloy powder and said base or core is a cobalt chrome alloy.

12. The method according to claim 4, wherein said first layer is a titanium powder and said base or core is a cobalt chrome alloy.

13. The method according to claim 4, wherein said first layer is a niobium powder and said base or core is a cobalt chrome alloy.

14. The method according to claim 4, wherein said first layer is a tantalum powder and said base or core is a cobalt chrome alloy.

15. The method according to claim 4, wherein said first layer is a niobium powder and the base or core is a titanium alloy.

16. The method according to claim 4, wherein said first layer is a titanium powder and said base or core is a titanium alloy.

17. The method according to claim 4, wherein said first layer is a tantalum powder and said base or core is a titanium alloy.

18. The method according to claim 4, wherein said first layer is a stainless steel alloy and said base or core is a stainless steel alloy.

19. The method according to claim 4, wherein said first layer is a titanium powder and said base or core is a stainless steel alloy.

20. The method according to claim 4, wherein said first layer is a tantalum powder and said base or core is a stainless steel alloy.

21. The method according to claim 4, wherein said first layer is a niobium powder and said base or core is a stainless steel alloy.

22. The method according to claim 4, wherein said first layer is a niobium powder and said base or core is niobium.

23. The method according to claim 4, wherein said first layer is a tantalum powder and said base or core is tantalum.

24. The method according to claim 4, wherein said first layer is a niobium powder and said base or core is a cobalt chromium alloy, wherein said niobium forms a bond coat between said cobalt chromium alloy and said niobium powder, said successive layers of powder including at least one layer of titanium powder are deposited onto said bond coat forms the ingrowth structure.

25. The method according to claim 4, wherein said first layer is a tantalum powder and said base or core is a cobalt chromium alloy, wherein said tantalum powder forms a bond coat between said cobalt chromium alloy and said tantalum powder, said successive layers of powder including at least one layer of titanium powder are deposited onto said bond coat which forms the ingrowth structure.

26. The method according to claim 4, wherein said first layer is tantalum powder and said base or core is a stainless steel alloy, wherein said tantalum powder forms a bond coat between said stainless steel alloy and said tantalum powder, said successive layers of powder including at least one layer of titanium powder are deposited onto said bond coat which forms the ingrowth structure.

27. The method according to claim 4, wherein said first layer is a niobium powder and said base or core consists of a stainless steel alloy, wherein said niobium powder forms a bond coat between said stainless steel alloy and said niobium powder, said successive layers of powder including at least one layer of titanium powder are deposited onto said bond coat which forms the ingrowth structure.

28. The method according to claim 4, wherein said core is integral with said resultant porous ingrowth structure and imparts additional physical properties to the overall construct.

29. The method accordingly to claim 4, wherein said core is detached from a resultant porous surface buildup.

30. The method according to claim 4, wherein a third element is added between said base and said first layer of powder to form a bond coat on said substrate.

31. A method of producing a three-dimensional porous tissue ingrowth structure comprising:

depositing a first layer of powder made from a metal selected from the group consisting of titanium, titanium alloys, stainless steel, cobalt chrome alloys, tantalum and niobium, onto a substrate;

scanning a laser beam having a power and a diameter with a speed between approximately 100 mms<sup>−

1</sup> to 260 mms<sup>−

1</sup> and a beam overlap less than zero over said metal powder to remelt said metal powder in order to create at least two solid lines so as to give a required pore size, the negative beam overlap allowing for a non-solid space between the two solid lines; and

depositing at least one additional layer of said powder onto said first layer and repeating said laser scanning steps for each successive layer.

32. The method according to claim 31, wherein the thickness of each of said layers is between 50 μ

m-2000 μ

m.

33. The method according to claim 31, wherein said substrate is a base or core made of a metal selected from the group consisting of titanium, titanium alloys, stainless steel, cobalt chrome alloys, tantalum and niobium, wherein said first layer is fused to said base or core.

34. The method according to claim 33, wherein the thickness of said powder is approximately 100 μ

m.

35. The method according to claim 31, wherein said laser power is approximately 78 W to 82 W.

36. The method according to claim 31, wherein said laser power is applied in a continuous wave.

37. The method according to claim 31, wherein said laser power is applied in a pulse wave.

38. The method according to claim 37, wherein said pulse wave repetition rate is between approximately 20 KHz to 50 KHz.

39. The method according to claim 31, wherein said method is carried out under an inert atmosphere.

40. The method according to claim 39, wherein the method is carried out under an Argon inert atmosphere.

41. The method according to claim 33, wherein said first layer is a cobalt chrome powder and said base or core is a titanium alloy.

42. The method according to claim 31, wherein said scanning speed is between 180 mms⁻

1 and 200 mms<sup>−

1</sup>.

43. The method according to claim 33, wherein said first layer of powder is niobium and said base or core consists of a titanium alloy, wherein said laser beam is a 72 W to 92 W continuous wave with a scanning speed range between about 160 mms⁻

1 to 240 mms<sup>−

1</sup> and said beam overlap is between 0% to −

500%.

44. The method according to claim 43, wherein said scanning speed is between approximately 190 mms⁻

1 and 240 mms<sup>−

1</sup>.

45. The method according to claim 33, wherein said first layer of powder is tantalum and said solid base or core is a titanium alloy, wherein said laser beam is a 72 W to 92 W continuous wave with a scanning speed range between about 160 mms⁻

1 to 240 mms<sup>−

1</sup> and said beam overlap is between 0% to −

500%.

46. The method according to claim 45, wherein said scanning speed is between about 160 mms⁻

1 to 200 mms<sup>−

1</sup>.

47. The method according to claim 45, wherein said beam overlap is −

40% and the laser beam power is 82 W.

48. The method according to claim 33, wherein said first layer of powder is titanium and said solid base or core is a cobalt chrome alloy, wherein said laser beam is a 72 W to 92 W continuous wave with a scanning speed range between about 160 mms⁻

1 to 240 mms<sup>−

1</sup> and said beam overlap is between 0% to −

500%.

49. The method according to claim 48, wherein said scanning speed range is between about 160 mms⁻

1 to 200 mms<sup>−

1</sup>.

50. The method according to claim 48, wherein said beam overlap is −

40% and said laser beam has a power of 82 W.

51. The method according to claim 33, wherein said first layer of powder is titanium and said solid base or core is a titanium alloy, wherein said laser beam is a 72 W to 92 W continuous wave with a scanning speed range between about 160 mms⁻

1 to 240 mms<sup>−

1</sup> and said beam overlap is between about 0% to −

500%.

52. The method according to claim 51, wherein said scanning speed is between 160 mms⁻

1 to 200 mms<sup>−

1</sup>.

53. The method according to claim 51, wherein said beam overlap is −

40% and said laser beam has a power of 82 W.

54. The method according to claim 33, comprising the additional step of subjecting a powder layer to a second laser scan with a scanning speed and beam overlap in an orthogonal direction to a first scan.

55. A method according to claim 54, wherein said scanning speed is between 160 mms⁻

1 to 200 mms<sup>−

1</sup>.

56. A method according to claim 54, wherein said beam overlap is between −

400% to −

600%.

57. The method according to claim 31, comprising the additional step of subjecting a powder layer to a second laser scan with a scanning speed and beam overlap in an orthogonal direction to a first scan.

58. A method according to claim 57, wherein said scanning speed is between 160 mms⁻

1 to 200 mms<sup>−

1</sup>.

59. A method according to claim 57, wherein said beam overlap is between −

400% to −

600%.