Method of making cermet or cemented carbide powder

Abstract

A method of making a powder of dense and spherically shaped cemented carbide or cermet granules and a powder produced by the method is provided. The powder made according to the present method can be used in additive manufacturing such as 3D printing by the binder jetting technique. Moreover, a Hot Isostatic Pressing (HIP) process for manufacturing a product by using the powder is also disclosed.

1 . A method of making a powder of dense and spherically shaped cermet or cemented carbide granules, wherein the method comprises the steps of:
 (a) forming spherically shaped granules comprising metal, hard constituents and organic binder;   (b) mixing said spherically shaped granules with a sintering inhibitor powder to form a mixture of spherically shaped granules and sintering inhibitor powder;   (c) loading the mixture of spherically shaped granules and sintering inhibitor powder in a furnace chamber;   (d) heat-treating the mixture obtained in step (b) in the furnace chamber at a sintering temperature to remove organic binder from the spherically shaped granules and to sinter the hard constituents with the metal in each spherically shaped granule and thereby forming a mixture of sintered dense spherically shaped granules and sintering inhibitor powder;   (e) unloading the mixture of sintered dense spherically shaped granules and sintering inhibitor powder from the furnace chamber; and   (f) separating the sintering inhibitor powder from the sintered dense spherically shaped granules whereby a powder of dense and spherically shaped cermet or cemented carbide granules is formed.   
     
     
         2 . The method in accordance with  claim 1 , wherein the porosity inside each cermet or cemented carbide dense spherically shaped granule is less than 5 vol %. 
     
     
         3 . The method in accordance with  claim 1 , wherein the granule size of the sintered dense spherically shaped granules of the cermet or cemented carbide powder is of from 1 to 500 μm. 
     
     
         4 . The method in accordance with  claim 1 , wherein the heat treatment in the furnace chamber is performed at a sintering temperature above a solidus temperature of the metal in the spherically shaped granules. 
     
     
         5 . The method in accordance with  claim 4 , wherein the heat treatment in the furnace chamber is performed at a sintering temperature of from 30 to 100° C. above the solidus temperature of the metal in the spherically shaped granules. 
     
     
         6 . The method in accordance with  claim 1 , wherein the inhibitor powder includes an oxide. 
     
     
         7 . The method in accordance with  claim 1 , wherein the inhibitor powder includes carbon. 
     
     
         8 . The method in accordance with  claim 1 , wherein the inhibitor powder is separated from the sintered dense spherically shaped granules by sieving, air classification, hydrocyclone, flotation and/or fluidization. 
     
     
         9 . The method in accordance with  claim 7 , wherein the inhibitor powder is separated from the sintered dense spherically shaped granules by a thermochemical method using a gas at elevated temperature. 
     
     
         10 . The method in accordance with  claim 9 , wherein the thermochemical method is performed in a rotating tube furnace or in a fluidized bed furnace. 
     
     
         11 . A powder of cermet or cemented carbide made in accordance with the method of  claim 1 . 
     
     
         12 . The powder made in accordance with  claim 11 , wherein the powder is used in Additive Manufacturing. 
     
     
         13 . The powder made in accordance with  claim 11 , wherein the powder is used in a HIP application. 
     
     
         14 . A process for manufacturing a component comprising the following steps:
 (a) providing a powder in accordance with  claim 11 ;   (b) providing a form;   (c) filling the form with the powder;   (d) evacuating air from the form;   (e) sealing the form; and   (f) subjecting the form to Hot Isostatic Pressing (HIP) at a predetermined temperature, a predetermined pressure and for a predetermined time so that the powder in accordance with  claim 11  bond metallurgically and a solid body is formed, wherein the form is made of an alloy of zirconium or an alloy of titanium.   
     
     
         15 . The process according to  claim 14 , wherein the powder has a continuous particle size distribution in the range of from 1 to 500 μm. 
     
     
         16 . The process according to  claim 14 , wherein the predetermined temperature is above 900° C. 
     
     
         17 . The process according to  claim 14 , wherein the predetermined pressure is above 500 bar. 
     
     
         18 . The process according to  claim 14 , wherein said process is used for manufacturing a cemented carbide or cermet.