Method of Making Porous Metal Articles

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.

What is claimed is: 
     
         1 . A method of making a co-formed metal article, the method comprising:
 a. combining metal powder with a homogenizing aid to form metal granules;   b. blending at least a portion of the metal granules and a first extractable particulate to form a first feedstock;   c. forming a second feedstock using metal powder;   d. forming the first and second feedstock into a green article;   e. removing the first extractable particulate from the green article to form a metal matrix with first and second pore structures, the first and second pore structures being different from each other; and   f. sintering the metal matrix.   
     
     
         2 . The method of  claim 1 , wherein the step of forming a second feedstock uses metal granules. 
     
     
         3 . The method of  claim 1 , wherein the metal powder in the step of combining metal powder with a homogenizing aid is titanium, titanium hydride, tantalum, cobalt chrome, niobium, stainless steel, nickel, copper, aluminum, or combinations thereof. 
     
     
         4 . The method of  claim 1 , wherein the metal powder in the step of forming a second feedstock using metal powder also includes at least one of a homogenizing aid and an extractable particulate. 
     
     
         5 . The method of  claim 1 , wherein the first pore structure is less dense than the second pore structure. 
     
     
         6 . The method of  claim 1 , wherein the step of forming the first and second feedstock into a green article includes at least one machining step. 
     
     
         7 . The method of  claim 1 , further comprising forming a third feedstock using metal powder, and wherein the step of forming the first and second feedstock into a green article includes forming the first, second, and third feedstocks into a green article. 
     
     
         8 . The method of  claim 1 , wherein the first pore structure is formed on an external surface of the co-formed metal article. 
     
     
         9 . The method of  claim 1 , wherein the first pore structure has an 60-80 volume percent porosity and pore sizes in the range of 200-850 microns and the second pore structure has approximately 0-7 volume percent porosity. 
     
     
         10 . The method of  claim 1 , wherein the first extractable particulate is water soluble. 
     
     
         11 . The method of  claim 1 , wherein said step of blending metal granules to form a second feedstock includes blending a second extractable particulate and said step of removing the first extractable particulate from the green article also removes the second extractable particulate. 
     
     
         12 . A method of making a porous metal article, the method comprising:
 a. compacting metal powder using a mold;   b. adding a layer of metal powder granules mixed with an extractable particulate to the compacted metal powder;   c. compacting the layer of metal powder granules mixed with an extractable particulate to form a green article with defined layers of materials;   d. removing the extractable particulate by immersing the green article in a liquid;   e. sintering the green article.   
     
     
         13 . The method of  claim 12 , wherein the metal powder is titanium, titanium hydride, tantalum, cobalt chrome, niobium, stainless steel, nickel, copper, aluminum, or combinations thereof. 
     
     
         14 . The method of  claim 12 , wherein the metal powder granules are formed with titanium, titanium hydride, tantalum, cobalt chrome, niobium, stainless steel, nickel, copper, aluminum, or combinations thereof. 
     
     
         15 . The method of  claim 12 , wherein said step of compacting metal powder using a mold includes compacting either metal powder or metal granules. 
     
     
         16 . The method of  claim 12 , wherein said step of compacting metal powder using a mold includes titanium granules and a second extractable particulate. 
     
     
         17 . The method of  claim 12 , wherein the article includes two layers, with an exterior layer being more porous than an interior layer. 
     
     
         18 . The method of  claim 17 , wherein the interior layer is non-porous. 
     
     
         19 . The method of  claim 12 , wherein the liquid is water. 
     
     
         20 . The method of  claim 12 , wherein the metal powder is titanium powder and the metal powder granules are formed from titanium.