Physical and mechanical properties of hot-press sintering ternary CMA(CaMgAlO)and CMA(CaMgAlO)ceramics

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 C2M2A14ceramic is 98.67%.The thermal expansivity（50–1400℃）of CM2A8 and C2M2A14 ceramics is 9.24×10–6K–1 and 8.92×10–6K–1,respectively.The thermal conductivity of CM2A8 and C2M2A14 ceramic is 21.32 W/（m·K）and 23.25 W/（m·K）at 25℃and 18.76 W/（m·K）and 19.42 W/（m·K）as temperature rises to 350℃,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.