Ni-Coated Ti Powders

Abstract

The present invention relates to coated powder, comprising a Ti-bearing core and a Ni-bearing coating, which can be used for the production of porous Ni—Ti articles by the self-propagating high temperature synthesis (SHS) method. The obtained articles are ideally suited for use in biomedical applications. According to the invention, a coated powder is used comprising a metallic Ti-bearing core and a metallic Ni-bearing coating, characterised by a Ni:Ti atomic ratio of more than 0.5, preferably between 0.9 and 1.1, and more preferably between 0.96 and 1.04. By using coated powders, local fluctuations in composition are limited and well under control. Milling of powders and the ensuing contamination risks are avoided. The sintered objects obtained using coated powders have a more homogeneous porosity than that using mixed Ni and Ti powders.

1 - 12 . (canceled) 
   
   
       13 . A process of manufacturing a Ni-coated Ti powder comprising a metallic Ti-bearing core and a metallic Ni-bearing coating, wherein the coated powder has a Ni:Ti atomic ratio of more than 0.5, the process comprising the steps of:
 (a) providing a Ti-bearing powder and a Ni salt bearing aqueous solution;   (b) feeding the Ti-bearing powder and the Ni salt bearing solution into an autoclave together with a quantity of NH 4 OH;   (c) precipitating the Ni onto the Ti-bearing powder by hydrogen reduction; and   (d) washing, filtering and drying the slurry obtained, thereby producing a Ni-coated Ti powder.   
   
   
       14 . The process according to  claim 13 , wherein the Ni-coated Ti powder manufactured by the process has a Ni:Ti atomic ratio between 0.9 and 1.1. 
   
   
       15 . The process according to  claim 13 , wherein the Ni-coated Ti powder manufactured by the process has a Ni:Ti atomic ratio between 0.96 and 1.04. 
   
   
       16 . The process according to  claim 13 , wherein a quantity of ammonium salts is introduced into the autoclave together with the Ti-bearing powder, the Ni salt bearing solution, and the quantity of NH 4 OH. 
   
   
       17 . The process according to  claim 13 , whereby the Ni is precipitated onto the Ti-bearing powder at a temperature of at least 100° C. and a hydrogen pressure in the autoclave of at least 1.4 MPa. 
   
   
       18 . A process of manufacturing a powder mixture comprising a Ni-coated Ti powder, comprising the steps of:
 (a) providing a Ti-bearing powder and a Ni salt bearing aqueous solution;   (b) feeding the Ti-bearing powder and the Ni salt bearing aqueous solution into an   (c) precipitating the Ni onto the Ti-bearing powder by hydrogen reduction;   (d) washing, filtering and drying the slurry obtained, thereby producing the Ni-coated Ti powder; and   (e) intimately mixing the Ni-coated Ti powder with one or both of Ni-bearing and Ti-bearing powder.   
   
   
       19 . The process according to  claim 18 , wherein the powder mixture manufactured by the process has a Ni:Ti atomic ratio between 0.9 and 1.1. 
   
   
       20 . The process according to  claim 18 , wherein the powder mixture manufactured by the process has a Ni:Ti atomic ratio between 0.99 and 1.01. 
   
   
       21 . The process according to  claim 18 , wherein a quantity of ammonium salts is introduced into the autoclave together with the Ti-bearing powder, the Ni salt bearing solution, and the quantity of NH 4 OH. 
   
   
       22 . A process of manufacturing a porous sintered body based on a Ni—Ti alloy, comprising the steps of  claim 13 , and further comprising the step of subjecting the Ni-coated Ti powder to a self-propagating high temperature synthesis operation. 
   
   
       23 . A process of manufacturing a porous sintered body based on a Ni—Ti alloy, comprising the steps of  claim 18 , and further comprising the step of subjecting the powder mixture to a self-propagating high temperature synthesis operation.