Mechanical properties and microstructure of spark plasma sintered Al2O3-SiCw-Si3N4 composite ceramic tool materials

Abstract

In this study, Al2O3-SiCw-Si3N4-based ceramic tool materials were fabricated by spark plasma sintering technique. The impact of sintering temperature on mechanical properties and local microstructure was thoroughly investigated. Moreover, detailed comparison was performed between spark plasma sintering and early hot-pressing sintering methods. Evolution law and mechanism of high-temperature mechanical properties were also investigated. Composites with higher density and enhanced mechanical properties were obtained by spark plasma sintering at temperature of 1500 °C, which was 100 °C lower than hot-pressing temperature. The cross-interlocking structure of generated β-Sialon particles and silicon carbide (SiC) whiskers could effectively improve mechanical properties of material configuration. Moreover, Vickers hardness and fracture toughness of ceramic composites decreased by elevating temperature (20–1000 °C); however, following percentages at 1000 °C were still maintained with respect to values at room temperature, i.e., 67 and 51%. This effect is attributed to existence of Sialon phase, healing of partial cracks, as well as manifestation of whisker pullout process. As a result, decreased attenuation rate under high-temperature conditions of respective mechanical properties was observed. Our approach provides useful insights into potential fabrication of novel material configurations with relatively low thermal budget and enhanced mechanical performance.