Method of producing tungsten carbide

Abstract

The present invention relates to a method of producing tungsten carbide by gas phase direct carburization of a tungsten-oxide containing starting material, wherein the starting material is reacted with a reaction gas at an increased temperature. The starting material is first heated to a first temperature greater than or equal to 600° C., before reacting with a reaction gas while increasing the temperature to a second temperature that does not exceed 850° C., wherein the reaction gas is selected from the group consisting of CO and a COH 2 gas mixture comprising up to 20% by volume H 2 .

1 - 9 . (canceled)  
     
     
         10 . A method of producing tungsten carbide by gas phase direct carburization comprising: (i) heating a starting material comprising tungsten-oxide to a first temperature greater than or equal to 600° C., (ii) reacting the heated starting material with a reaction gas while increasing the temperature to a second temperature that does not exceed 850° C.; 
 wherein the reaction gas is selected from the group consisting of CO and a CO and H 2  gas mixture comprising up to 20% by volume H 2 .    
     
     
         11 . The method of  claim 10 , wherein the starting material is heated in a protective gas atmosphere prior to heating in the presence of the reaction gas.  
     
     
         12 . The method of  claim 10 , wherein the starting material in the presence of a reaction gas is heated at a rate of 40-55° C./hour.  
     
     
         13 . The method of  claim 11 , wherein the starting material in the presence of a reaction gas is heated at a rate of 40-55° C./hour.  
     
     
         14 . The method of  claim 10 , wherein the starting material is doped with chromiferous and/or vanadiferous compounds prior to heating in the presence of the reaction gas.  
     
     
         15 . The method of  claim 11 , wherein the starting material is doped with chromiferous and/or vanadiferous compounds prior to heating in the presence of the reaction gas.  
     
     
         16 . The method of  claim 12 , wherein the starting material is doped with chromiferous and/or vanadiferous compounds prior to heating in the presence of the reaction gas.  
     
     
         17 . The method of  claim 13 , wherein the starting material is doped with chromiferous and/or vanadiferous compounds prior to heating in the presence of the reaction gas.  
     
     
         18 . The method of  claim 10 , wherein heating the starting material in the presence of a reaction gas occurs in a fluidized bed furnace.  
     
     
         19 . A tungsten carbide having a lattice distance x in the c-direction, wherein 2.850<x≦2.870 Angström, having a content of bound carbon in a range of from 5.86% to 6.08% by weight, wherein the tungsten carbide is monophasic.  
     
     
         20 . The tungsten carbide of  claim 19 , wherein the tungsten carbide is produced by a direct carburization method comprising: (i) heating a starting material comprising tungsten-oxide to a first temperature greater than or equal to 600° C., (ii) reacting the heated starting material with a reaction gas while increasing the temperature to a second temperature that does not exceed 850° C.; 
 wherein the reaction gas is selected from the group consisting of CO and a COH 2  gas mixture comprising up to 20% by volume H 2 .    
     
     
         21 . A hard metal comprising a tungsten carbide according to  claim 19 .  
     
     
         22 . A hard metal comprising a tungsten carbide according to  claim 20.