Laser-produced porous surface
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.
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/mm 2 , 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 μm-2000 μm.
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 −1 to 260 mms −1 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 μm-2000 μm.
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 μm.
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 −1 .
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 −1 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 −1 .
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 −1 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 −1 .
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 −1 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 −1 .
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 −1 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 −1 .
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 −1 .
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 −1 .
59. A method according to claim 57 , wherein said beam overlap is between −400% to −600%.