Effects of carbide grain growth inhibitors on the microstructures and mechanical properties of WC-SiC-Mo_2C hard ceramics

摘要

Cr_3C_2, NbC, or ZrC was added to WC-4.85 mol% SiC-1 mol% Mo_2C ceramics and sintered at 1600 °C using a resistance-heated hot-pressing machine. Dense ceramics containing 0-0.3 mol% Cr_3C_2, 0-3 mol% NbC, and 0-10 mol% ZrC were obtained. An additive carbide-based solid solution was observed only for NbC and ZrC additions. The coarse plate-like WC grains disappeared with the addition of Cr_3C_2, NbC, or ZrC and the ceramics consisted of fine equiaxed WC grains. Higher hardnesses, 19.4-21.8 GPa, were measured for the carbide-added WC-SiC-Mo_2C ceramics than for the WC-4.85 mol% SiC ceramics because of the disappearance of coarse plate-like grains. The addition of a small amount of ZrC improved the fracture toughness without reducing the hardness.