Microstructure and Mechanical Properties of CrN-Based Composites with the Combined Addition of ZrO₂(3Y) and Al₂O₃

Abstract

Chromium nitride (CrN) powder consisting of granular particles of-2μm has been prepared by self-propagating high-temperature synthesis (SHS). SHS was conducted under a nitrogen pressure of 12 MPa using commercially available Cr powder. Dense monolithic CrN ceramics and CrN-based composites with the combined addition of 70vol%ZrO₂(3Y)/30vol%Al₂O₃ have been fabricated by hot isostatic pressing for 7.2 ks at 1573 K and 196 MPa. The former ceramics composed of pure CrN. (-9.8μm) exhibit a bending strength (σ_b) of 400 MPa and a fracture toughness (K_IC) of 3.3 Mpa⋅ m^1/2 In the latter composites almost all the ZrO₂(3Y) (0.1-0.2μm) and A1₂O₃ (0.3 -0.6μm) grains are located at the grain boundaries of CrN (2-3μm). The high values of σ_b (1090 MPa) and K_IC (5.0 Mpa⋅m^1/2) are obtained in the composites with 40vol% combined addition.