[en] Grain growth inhibitors, nanotungsten carbide, mixtures, high energy milling.
Abstract :
[en] In cemented carbides based on ultrafine carbide powders the use of growth inhibitors is indispensable for the preservation of satisfactory mechanical properties of sintered product. The inhibitors manifest their effect by blocking tungsten carbide diffusion through the metal binder. Use of chromium carbide as inhibitor has proved very effective, especially by ensuring a high toughness for the alloys where it is used. Following some according to recent studies that have proved that the diffusion distance is very important in effective inhibition of carbide particles growth, there are limits which should not be exceeded. An homogeneous distribution and a lower inhibitor particle size are the premises to obtain a uniform microstructure. This study was aimed at obtaining homogeneous carbide-binder-inhibitor mixtures. To this end, four (4) Co + inhibitor compositions have been milled in a planetary mill under dry and wet conditions. Grinding effect on the homogeneity of the powder was studied by X-ray diffraction, optical and electron microscopy on polished samples. Subsequently, the optimal mixture will be mixed with nano tungsten carbide and sintered to verify effectiveness.