Enhancing room and high temperature performance on WC-Co cemented carbide via nitrogen modification

Incorporating nitrogen-containing inhibitors has been shown to significantly improve the comprehensive mechanical properties of cemented carbides at room temperature. However, research on the role of nitrogen itself and its impact at elevated temperatures is still limited. In this study, a series of cemented carbides with varying nitrogen content were synthesized by introducing (Cr0.9V0.1)2(C, N) as an inhibitor. The addition of nitrogen results in a continuous refinement in the grain size of WC, thereby increasing hardness. Moreover, the transverse rupture strength (TRS) and fracture toughness initially increase and subsequently decrease. Building on these findings, the paper further investigates the role of nitrogen on the high-temperature mechanical and thermal characteristics of cemented carbides. At temperatures below 600 degrees C, nitrogen incorporation notably improves the hardness of cemented carbide while mitigating its rate of softening. Furthermore, nitrogen-modified cemented carbide exhibits favorable thermal conductivity. Nitrogen-modified cemented carbide demonstrates excellent mechanical properties (TRS = 5461.6 MPa, HV30(room temperature) = 1968.6 kg/mm2, KIC(room temperature) = 10.51 MPa center dot m1/2, HV5(800 degrees C) = 1446.1 kg/mm2 and KIC(800 degrees C) = 17.10 MPa center dot m1/2 at 0.03 wt% nitrogen. The results of our research demonstrate the significant potential of nitrogen-containing inhibitors in the fabrication of high-performance cemented carbide cutting tools.