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

Abstract

The new ternary CM 2 A 8 (CaMg 2 Al 16 O 27 ) and C 2 M 2 A 14 (Ca 2 Mg 2 Al 28 O 46 ) 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 CM 2 A 8 and C 2 M 2 A 14 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 CM 2 A 8 and C 2 M 2 A 14 ceramics is 0.18% and 0.13%, and their average bulk density is 3.66 g/cm 3 and 3.71 g/cm 3 , respectively. The relative density of CM 2 A 8 ceramic is 98.12% and that of C 2 M 2 A 14 ceramic is 98.67%. The thermal expansivity (50-1400 ℃) of CM 2 A 8 and C 2 M 2 A 14 ceramics is 9.24×10 -6 K -1 and 8.92×10 -6 K -1 , respectively. The thermal conductivity of CM 2 A 8 and C 2 M 2 A 14 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 CM 2 A 8 ceramic, the flexural strength is 248 MPa, the fracture toughness is 2.17 MPa·m 1/2 , and the Vickers hardness is 12.26 GPa. For C 2 M 2 A 14 ceramic, the flexural strength is 262 MPa, the fracture toughness is 2.23 MPa·m 1/2 , and the Vickers hardness is 12.95 GPa.

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