Mullite–TiC–c-BN–c-ZrO2 materials Produced by Spark-Plasma Sintering and Their Properties

Abstract

Different c-BN/c-ZrO₂ ratios are shown to affect the phase composition, microstructure, relative density, open porosity, linear shrinkage, physicomechanical properties, and linear correlation of the elastic modulus and toughness of mullite–TiC–c-BN–c-ZrO₂ samples during spark-plasma sintering at pressing load 70 MPa and 1200 – 1600°C. The synthesized TiC and c-BN powders and c-ZrO₂ spark-plasma sintered at 1400°C are characterized by extensive phase crystallization. Mullite and TiC develop profusely in sintered samples with different c-BN/c-ZrO₂ ratios. Increasing the c-BN/c-ZrO₂ ratio promotes ingrowth of more c-BN than c-ZrO₂ at 1200 – 1600°C and causes a less uniformly and densely sintered crystalline microstructure with many pores to form at 1500°C. This sample has lower physicomechanical properties, a poorer linear correlation of elasticity modulus and toughness at 1200 – 1600°C, and lower crack resistance at 1500°C.