Preparation of Ti-coated diamond/WC-Co-based cemented carbide composites by microwave-evaporation titanium-plating of diamond particles and microwave hot-press sintering

Abstract

Diamonds are considered ideal additives for improving the wear resistance of cemented carbide materials and thus for extending their service life. However, the poor wettability and thermal stability of diamonds limit their effectiveness. To solve this problem, in this study, microwave-evaporation technology, a low-cost and simple approach, was used to prepare a uniform titanium coating on diamond surface with an optimized diamond-to-titanium-hydride ratio of 5:3 and an optimized holding time of 1 h at 760 °C. The TiC interlayer with needle-rod microstructure was observed. The coating could increase the oxidation weight-loss temperature by 152.7 °C. The different steps of the high-temperature ablation process of Ti-coated diamond were also revealed. Then, Ti-coated diamond/WC-Co-based cemented carbide composites with uniform microstructure, good interfacial bonding, and no thermal burning loss of diamond were prepared using microwave hot-press sintering with a temperature of 1050 °C only and a pressure of 40 MPa, leading to good wear resistance. The wear rate of the composites prepared with Ti-coated diamond was 25.7% lower at room temperature and 50.7% lower at 400 °C than that of the uncoated diamond. This approach minimized the thermal damage to diamond since both Ti-coated diamond and the composites were prepared at low temperatures.