Process for the preparation of pre-alloyed powders for diamond tools, and the powders so obtained

Abstract

A metal powder has a formula FeaCubNicCodSnePfMogWhAxOy, wherein, in weight %, a>50, 5<b<25, c<20, d<5, e<5, 0.5<f<5, 0.5<g+h<5, x+y<5, and a+b+c+d+e+f+g+h+x+y=100. A represents one or more elements having a Gibbs free energy of oxidation at 700° C. which is lower than the Gibbs free energy of oxidation of Mo at 700° C. The pre-alloyed powder is useful for the manufacture of metal-bonded diamond tools. The powder can have a low cobalt content, or even be cobalt-free, yet remain suitable for the production of diamond-loaded segments having harness and bending characteristics approaching or exceeding that of cobalt.

1 . A metal powder according to the formula FeaCubNicCodSnePfMogWhAxOy, with, in weight %, a>50, 5<b<25, c<20, d<5, e<5, 0.5<f<5, 0.5<g+h<5, x+y<5, and a+b+c+d+e+f+g+h+x+y=100; whereby A represents one or more elements having a Gibbs free energy of oxidation at 700° C. which is lower than the Gibbs free energy of oxidation of Mo at 700° C. 
     
     
         2 . The metal powder according to  claim 1 , wherein the metal powder comprises a plurality of metal particles, wherein a major part of the individual metal particles comprises Fe and Cu and P and one or both of Mo and W. 
     
     
         3 . The metal powder according to  claim 1 , wherein x<0.50. 
     
     
         4 . The metal powder according to  claim 1 , wherein the ratio (g+h)/f<2.00. 
     
     
         5 . A precursor for preparing a metal powder, the precursor comprising:
 one or more P-bearing compounds, wherein P is present in an oxidised state, and   metal-bearing compounds bearing Fe, Cu and one or both of Mo and W, wherein the Fe, Cu and one or both of Mo and W are present in the metal bearing compounds in an oxidised state.   
     
     
         6 . The precursor according to  claim 5 , wherein the one or more P-bearing compounds comprise diammonium hydrogen phosphate. 
     
     
         7 . The precursor according to  claim 5 , wherein the metal bearing compounds comprise ammonium dimolybdate and/or ammonium metatungstate. 
     
     
         8 . The precursor according to  claim 5 , wherein the metal bearing compounds comprise Fe-oxide, -hydroxide, -oxyhydroxide, -carbonate, and/or -oxalate and wherein the metal bearing compounds comprise Cu-oxide, -hydroxide, -oxyhydroxide, -carbonate, and/or -oxalate. 
     
     
         9 . A pre-alloyed powder according to the formula FeaCubNicCodSnePfMogWh, with, in weight %, a>50, 5<b<25, c<20, d<5, e<5, 0.5<f<5, 0.5<g+h<5, and a+b+c+d+e+f+g+h>95%; wherein the powder is obtainable from a precursor according to  claim 5 .