Mechanical properties of Al₄SiC₄ bulk ceramics produced by solid state reaction

The mechanical properties at ambient and high temperature of Al₄SiC₄ bulk ceramics prepared by solid state reaction were investigated. By increasing the sintering temperature slightly, the room temperature bending strength increased up to 318 MPa, whereas, the fracture toughness decreased with the increase of the sintering temperatures. The high temperature bending strengths of the Al₄SiC₄ ceramics exhibited anomalous increases within certain temperature ranges especially at 1300 °C in air with the highest value of 449.7 MPa, i.e. about 1.5 times of that at room temperature (300 MPa). The self-healing behavior of the flaws on the specimen surface due to the oxidation of the surface layer of the Al₄SiC₄ ceramics is considered to be the main strength-enhancing mechanism at high temperatures.