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

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 degrees 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 degrees C and 1600 degrees C decreased with increasing SiBCN content, while for the composites with 10-20 vol% SiBCN, the residual bending strength increased by 140-147%.