Mechanical Properties and Microstructure of Al₂O₃/SiC Composite Ceramics for Solar Heat Absorber

Abstract

Al₂O₃/SiC composite ceramics were prepared from α-Al₂O₃ and SiC by a pressureless sinter method in this study. The effect of SiC contents on the mechanic properties, phase compositions and microstructure is studied. Experimental results show that the vickers hardness, wear resistance and thermal conductivity of the samples increase with the increase in the SiC content, and the hardness of the sample reaches 16.22 GPa, and thermal conductivity of the sample reaches 25.41 W/(m.K) at room temperature when the SiC content is 20 wt%(B5) and the sintering temperature is at 1 640 °C. Higher hardness means higher scour resistance, and it indicates that the B5 material is expected to be used for the solar heat absorber of third generation solar thermal generation. The results indicate the mechanism of improving mechanical properties of Al₂O₃/SiC composite ceramics: SiC plays a role in grain refinement that the grain of SiC inhibits the grain growth of Al₂O₃, while the addition of SiC changes the fracture mode from the intergranular to the intergranular-transgranular.

Keywords

Al₂O₃/SiC composite ceramics / hardness / thermal conductivity / solar heat absorption material

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