Mo–SiBCN metal-ceramic composites with enhanced and tunable thermophysical properties and thermal shock resistance

Abstract In this study, Mo–SiBCN metal-ceramic composites with or without sintering additives of MgO, Al2O3, and SiO2 were fabricated by hot-press sintering at 1800 °C/60 MPa/30 min to investigate their phase composition, microstructural evolution, mechanical properties, thermophysical properties and thermal shock resistance. With the increase in amorphous SiBCN, a competition of reaction products between Mo and SiBCN as Mo3Si → Mo3Si + Mo5Si3 + MoSi2 → Mo4.8Si3C0.6 + Mo5Si3 + MoSi2 → Mo4.8Si3C0.6 were detected. Meanwhile, the bulk density, elastic modulus and bending strength of the Mo–SiBCN composites gradually decrease with increasing SiBCN content, but their hardness first increases and subsequently decreases, reaching the highest value of 14.46 ± 0.43 GPa with 30 vol% SiBCN incorporation. Due to the oxide additives that promoted the sintering of composites, the bending strength and hardness of Mo–SiBCN composites with the additives increased 3–6 times. The residual bending strength of the Mo–SiBCN composites after thermal shock at 900 °C and 1600 °C decreased with increasing SiBCN content, while for the composites with 10–20 vol% SiBCN, the residual bending strength increased by 140–147%.