Tungsten carbide made by doped grains is widely used in modern tools, wear resistance, high temperature resistance and corrosion resistance materials depending on the properties of high melting point, hardness and strength. There are many inhibitors to control the growth of tungsten carbide grains, among them Cr₃C₂ and VC are commonly used, but Cr₃C₂ has the better inhibition effect. In the present, carbide powder is mixed with tungsten powder and carbon to prepare WC powder containing the inhibitors. However, because inhibitors are not uniform, it leads part of WC grains non - expected growth, thus affects properties of cemented carbide. In this paper, a new way to dope chromium in the crystallization of ammonium paratungstate is put off, and the performance of Cr was analyzed.
 

Adding chromium acetate(CH₃COO)₃Cr into ammonium tungstate(pH≥9), crystallization to get ammonium paratungstate (APT) with chromium. The reactions are as follows

K_sp=6.3*10^-33(25℃)  K_sp is the concentration multiplication of Cr(OH)₃

 

pH value of initial and total precipitation on different initial concentration of Cr is shown as below:

 

Chromium doped in APT crystallization, it has varieties of behavior, and we analyze the following three points:

1. Different content chromium affects it in APT powder, with the amount of chromium increasing, chromium in APT powder increases linearly. Cr(OH)₃ with unsaturation is the main precipitation of chromium in APT. Controlling the content of chromium in the crystallization can produce APT with different content chromium.