Characterization of functionally gradient Ti(C, N)-based cermets fabricated by vacuum liquid phase sintering and nitriding treatment during cooling

摘要

Functionally graded Ti(C,N)-based cermets were prepared by a simple and economic procedure which combined vacuum liquid phase sintering with nitriding treatment during cooling in one cycle. The prepared cermets were investigated using scanning electron microscope (SEM), energy dispersive X-ray analysis (EDX) and electron probe microanalysis (EPMA). It was found that the high nitrogen activity in the surface region drove titanium to transport outwards and accordingly forced nickel to diffuse inwards. As a result, a hard graded layer from the surface region down to about 200 urn depth enriched in carbonitride grains and depleted in binder phase was introduced, which improved significantly the hardness of the graded cermets.