Function of Inhibitor in Process Nanometer Tungsten Carbide Products
The grain of raw nanometer tungsten carbide materials grows up very quickly in sintering process due to its large specific surface area(powder diameter between 5~20nm WC powder, the specific surface area up to 38m2/g),especially some grains grow up abnormally resulting in breaking of tungsten carbide products However ,it is very effective to restrain growing of the WC grains by means of adding inhibitors such as VC,Mo2C,Cr3C2,NbC,TaC,TiC etc .Practice shows that VC is the best inhibitor ,followed by Cr3C2 ,NbC and TaC.Studies have shown that the inhibitors added in WC carburization stage play better than they are added directly in ball milling stage ,as if they are added in WC carburization stage ,the inhibitors are distributed more uniformly in the blending powders, meanwhile the microstructure for WC is higher uniformity with more active dispersivity.
In addition, the nanoscale powder is as fine as molecular and atomic scale ,thus agglomeration is very serious .Hence ,the diffusion and uniform combination for the nanometer tungsten carbide powders can not be ignored.
