Physical and mechanical properties of hot-press sintering ternary CM2A8 (CaMg2Al16O27) and C2M2A14 (Ca2Mg2Al28O46) ceramics

Abstract

Abstract The new ternary CM2A8 (CaMg2Al16O27) and C2M2A14 (Ca2Mg2Al28O46) pure and dense ceramics were first prepared by a hot-press sintering technique, and their physical and mechanical properties were investigated. The purity of obtained CM2A8 and C2M2A14 ceramics reaches 98.1 wt% and 97.5 wt%, respectively. Their microstructure is dense with few observable pores, and their grain size is about a few dozen microns. For their physical properties, the average apparent porosity of CM2A8 and C2M2A14 ceramics is 0.18% and 0.13%, and their average bulk density is 3.66 g/cm3 and 3.71 g/cm3, respectively. The relative density of CM2A8 ceramic is 98.12% and that of C2M2A14 ceramic is 98.67%. The thermal expansivity (50–1400 °C) of CM2A8 and C2M2A14 ceramics is 9.24×10–6 K–1 and 8.92×10–6 K–1, respectively. The thermal conductivity of CM2A8 and C2M2A14 ceramic is 21.32 W/(m·K) and 23.25 W/(m·K) at 25 °C and 18.76 W/(m·K) and 19.42 W/(m·K) as temperature rises to 350 °C, respectively. In addition, the mechanical properties are also achieved. For CM2A8 ceramic, the flexural strength is 248 MPa, the fracture toughness is 2.17 MPa·m1/2, and the Vickers hardness is 12.26 GPa. For C2M2A14 ceramic, the flexural strength is 262 MPa, the fracture toughness is 2.23 MPa·m1/2, and the Vickers hardness is 12.95 GPa.