Analysis of mechanical properties of Al2O3-cBN-hBN composites and identification of main influencing factors

Al2O3-cBN-hBN self-lubricating ceramics were synthesized by using a high-pressure sintering method. The mapping relationships between sintering thermodynamic conditions, component content, and mechanical properties were established using the response surface method. The main factors influencing the mechanical properties are clarified. The formation mechanism of the excellent mechanical properties is explained. It is found that the undesired phase transformation from cBN to soft hBN can be effectively inhibited by using a low-temperature and high-pressure sintering process. Sintering temperatures improve the relative densities and elastic modulus of self-lubricating ceramic but have little effect on the hardness and fracture toughness. cBN content is the main factor affecting the mechanical properties of the composites. The microcracks developed during the high-pressure sintering process contribute to the fracture toughness of the composites.