Fabrication, microstructure and abrasive wear characteristics of an in situ tantalum carbide ceramic gradient composite

摘要

A tantalum carbide (TaC) ceramic gradient composite was produced on the surface of an iron matrix by an in situ technique comprising a casting process and a subsequent heat treatment. In this study, the phase constituents, microstructure, microhardness, and wear resistance of the gradient composite were analysed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), a Vickers hardness tester, and a wear resistance tester, respectively. The results showed that the gradient composite can be divided into three zones according to the variation in the volume fraction of TaC ceramic particulates, which can be labelled as follows: micro-nanostructure TaC ceramic dense layer, micro-structure TaC ceramic layer and TaC ceramic particulate composite layer, where the combination between the gradient composite and matrix present a perfect metallurgical bond. The mean micro-hardness of the TaC ceramic gradient composite gradually decreased from the upper surface to the matrix due to the TaC ceramic particulates growing larger and their volume fraction gradually decreasing in different reaction zones.