Power of tungsten alloy with transition metal dissolved therein as solid solution and process for producing the same

Abstract

This invention is related to a powder of a tungsten alloy with a transition metal dissolved therein as a solid solution that is suitable as material for a cemented carbide represented by formula [1] and a material for a catalyst. The powder of tungsten alloy is characterized in that at least one transition metal element selected from the group consisting of cobalt, iron, manganese and nickel is dissolved as a solid solution in a tungsten grating and a peak derived from a bcc tungsten phase appears in an X-ray diffraction diagram. Formula [1]: M−W wherein M represents one or more elements selected from Co, Fe, Mn and Ni. The use of tungsten alloy powder can provide a tungsten carbide with a transition metal dissolved therein as a solid solution in which a solid solution phase comprising at least one transition metal element selected from the group consisting of cobalt, iron, manganese and nickel, tungsten and carbon is included in a tungsten carbide skeleton, and a tungsten carbide diffused cemented carbide.

1 . A tungsten alloy powder with a transition metal dissolved therein as a solid solution represented by Formula [1] prepared by using an ammonium paratungstate aqueous solution and a transition metal complex salt aqueous solution, in which at least one transition metal element selected from the group consisting of cobalt, iron, manganese and nickel is dissolved in a tungsten grating and a peak derived from a bcc tungsten phase appears in an X-ray diffraction diagram.
   M−W  Formula [1]
   wherein M represents one or more selected from Co, Fe, Fe—Mn and Ni.   
     
     
         2 . The tungsten alloy powder with a transition metal dissolved therein as a solid solution according to  claim 1 , represented by Formula [2]:
 in which cobalt is dissolved in a tungsten grating and cobalt is partially substituted by one or more selected from the group consisting of iron, manganese and nickel.
   Co−M1−W  Formula [2]
 
   wherein M1 represents one or more elements selected from Fe, Fe−Mn and Ni.   
     
     
         3 . The tungsten alloy powder with a transition metal dissolved therein as a solid solution according to  claim 1 , in which iron is dissolved in a tungsten grating and iron is partially substituted by one or more selected from the group consisting of cobalt, manganese and nickel.
   Fe−M2−W  Formula [3]
   wherein M2 represents one or more elements selected from Co, Mn and Ni.   
     
     
         4 . The tungsten ally powder with a transition metal dissolved therein as a solid solution according to either one of  claim 1 , wherein 40 to 10 mol % of one or more metal selected from the group consisting of cobalt, iron, manganese and nickel is dissolved in 60 to 90 mol % of tungsten. 
     
     
         5 . A process for producing the transition metal dissolved tungsten powder, which comprises:
 mixing an ammonium paratungstate aqueous solution containing tungsten ions with an acetate aqueous solution containing at least ions of one transition metal selected from the group consisting of cobalt, iron, manganese and nickel, wherein the mixing is performed such that the tungsten ions are 60 to 90 mol % and the transition metal ions are 40 to 10 mol %,   drying the mixed aqueous solution by distillation or spraying,   thermally decomposing the resulting solid, followed by hydrogen thermal reduction, to prepare a transition metal-dissolved tungsten alloy powder represented by Formula [1] of M−W (wherein M represents one or more selected from Co, Fe, Mn and Ni), in which a transition metal element is dissolved.   
     
     
         6 . (canceled) 
     
     
         7 . The tungsten ally powder with a transition metal dissolved therein as a solid solution according to  claim 2 , wherein 40 to 10 mol % of one or more metal selected from the group consisting of cobalt, iron, manganese and nickel is dissolved in 60 to 90 mol % of tungsten. 
     
     
         8 . The tungsten ally powder with a transition metal dissolved therein as a solid solution according to  claim 3 , wherein 40 to 10 mol % of one or more metal selected from the group consisting of cobalt, iron, manganese and nickel is dissolved in 60 to 90 mol % of tungsten.