Porous structure and methods of making same

Abstract

The present disclosure provides methods to improve the properties of a porous structure formed by a rapid manufacturing technique. Embodiments of the present disclosure increase the bonding between the micro-particles 5 on the surface of the porous structure and the porous structure itself without substantially reduce the surface area of the micro-particles. In one aspect, embodiments of the present disclosure improves the bonding while preserving or increasing the friction of the structure against adjacent materials.

1 . A method comprising the step of:
 forming a porous structure by rapid manufacturing technique utilizing a metallic material, wherein the rapid manufacturing technique is selected from group consisting of direct metal fabrication, direct metal laser sintering, and solid free-form fabrication;   treating the porous structure with a thermal treatment to increase the bond strength between a plurality of micro-particles attached to said porous structure and said porous structure without substantially reducing the surface area of the porous structure; and   selecting a time and temperature for the thermal treatment, wherein the time is between 30 minutes to 300 minutes and the temperature is between about 800 degrees C. and about 1200 degrees C.   
     
     
         2 . The method of  claim 1 , wherein the thermal treatment provides average micro-particle diameter to neck diameter ratio greater than 1 and less than 5. 
     
     
         3 . The method of  claim 1 , wherein the thermal treatment is selected from the group consisting of high vacuum furnace treatment, resistive heat treatment, radiative heat treatment, electron beam scanning, laser beam scanning, and a combination thereof. 
     
     
         4 . The method of  claim 1 , wherein the selection step is configured to improve the bonding between said plurality of micro-particles and said porous structure while at least substantially preserving a desired roughness and friction of said porous structure. 
     
     
         5 . The method of  claim 1 , wherein the selection step is configured to improve the bonding between said plurality of micro-particles and said porous structure while increasing the roughness of said porous structure. 
     
     
         6 . The method of  claim 1 , wherein the plurality of micro-particles comprises a powder selected from the group consisting of metal, ceramic, metal-ceramic (cermet), glass, glass-ceramic, polymer, composite and combinations thereof. 
     
     
         7 . The method of  claim 1 , wherein the metallic material is selected from the group consisting of titanium, titanium alloy, zirconium, zirconium alloy, niobium, niobium alloy, tantalum, tantalum alloy, nickel-chromium (e.g., stainless steel), cobalt-chromium alloy and combinations thereof. 
     
     
         8 . The method of  claim 7 , wherein the porous structure comprises titanium alloy, the temperature of the thermal treatment of the titanium alloy structure is between greater than about 800 degrees C. and about 1200 degrees C. 
     
     
         9 . The method of  claim 1 , wherein the porous structure is thermally treated from about 30 minutes to 300 minutes. 
     
     
         10 . The method of  claim 1 , wherein the thermal treatment is performed in a vacuum or inert gas furnace below atmospheric pressure. 
     
     
         11 . The method of  claim 1 , wherein the thermal treatment is performed in a vacuum or inert gas furnace with oxygen partial pressure below about 0.02 torr. 
     
     
         12 . The method of  claim 1 , wherein the time and temperature of the thermal treatment is determined based at least on the size of the plurality of micro-particles and the solid-state diffusion coefficient of the plurality of micro-particles. 
     
     
         13 . The method of  claim 1 , wherein the time and temperature of the thermal treatment is determined based at least on the desired aspect ratio of the porous structure. 
     
     
         14 . The method of  claim 1 , wherein the time and temperature of the thermal treatment is determined based at least on the desired friction of a surface of the porous structure. 
     
     
         15 . The method of  claim 1 , wherein the selecting step comprises determining a friction value of said porous structure prior to treatment, determining a friction value of said porous structure subsequent to treatment, adjusting the time and temperature of said treatment until the friction value prior to treatment is at least substantially the same as the friction value subsequent to treatment. 
     
     
         16 . The method of  claim 1 , wherein the selecting step comprises determining a friction value of said porous structure prior to treatment, determining a friction value of said porous structure subsequent to treatment, adjusting the time and temperature of said treatment until the friction value subsequent to treatment is higher than said friction value prior to treatment. 
     
     
         17 . The method of  claim 1 , wherein the selected time and temperature for said treatment results in the friction value prior to treatment being within about 0% to less than about 15% of the friction value subsequent to treatment. 
     
     
         18 . The method of  claim 17 , wherein the friction value comprises a coefficient of friction when said porous structure is articulated against an analogue component. 
     
     
         19 . The method of  claim 17 , wherein the friction and/or roughness of structure is measured using an inclined plane method or using a pin-on-disk testing apparatus. 
     
     
         20 . A method comprising the step of:
 forming a titanium alloy porous structure formed by rapid manufacturing technique, wherein the rapid manufacturing technique is selected from group consisting of direct metal fabrication, direct metal laser sintering, and solid free-form fabrication;   treating the porous structure with a thermal treatment to increase the bond strength between a plurality of micro-particles attached to said porous structure and said porous structure without substantially reducing the surface area of the porous structure, wherein the thermal treatment is performed in a vacuum or inert gas furnace below atmospheric pressure; and   selecting a time and temperature for the thermal treatment, wherein the time is between 30 minutes to 300 minutes and the temperature is between than about 800 degrees C. and about 1200 degrees C., and wherein the time and temperature of the thermal treatment is determined based at least on the desired friction of a surface of the porous structure.