Effects of CTC(P) Modification on Microstructure and Wear Behavior of CTC(P)-NiCrBSi/Heat Resistant Steel Composite Layer

A CTC(P)-NiCrBSi/heat resistant steel composite layer was designed and fabricated by vacuum fusion sintering. The structure of the composite layer was similar to reinforced concrete. Numerous reinforced regions with a cylindrical shape were evenly distributed in the heat resistant steel. Modified cast tungsten carbide particles (CTC(P)) reinforced NiCrBSi matrix composite constituted the reinforced region (CTC(P)-NiCrBSi). The microstructure of the composite layers was investigated by scanning electron microscope (SEM), energy dispersive x-ray spectrometer (EDS), and image analysis. The wear behavior of the composite layer was estimated on the ring-on-disc rig at a temperature range of room temperature (RT) to 800 °C in air. The microstructure and wear behavior of the composite layer with modified CTC(P) were compared with those with primary CTC(P). The results showed that the poor chemical resistance of W(2)C and the interdiffusion of elements were responsible for the dissolution of unmodified CTC(P) in the molten NiCrBSi alloy. A WC outer shell formed on the surface of the CTC(P) after surface carburizing modification. The WC outer shell could effectively resist the dissolution of CTC(P) in NiCrBSi during the sintering process. The content of WC/W(2)C in modified CTC(P)-NiCrBSi increased by about 12.0 vol. % when compared with that in the primary CTC(P)-NiCrBSi. The wear rate of the composite layer with modified CTC(P) was lower than that with primary CTC(P) between RT and 700 °C. The wear rates of the composite layer decreased with increasing temperature from RT to 700 °C and increased above 700 °C.