Fabrication and characterization of SiC–TiB2 composite ceramics used as infrared source material

Abstract

SiC–TiB2 composite ceramics were fabricated by pressureless sintering at 2200 °C using B4C and C as sintering additives. The effects of TiB2 content on the microstructure, electrical properties, infrared radiation properties and mechanical properties of the composites have been systematically studied. The prepared composites have high relative density (>98%) and good mechanical properties. The existence of Schottky barrier at the SiC–SiC grain boundary makes SiC-based ceramics showing high resistivity and nonlinear electrical feature. The introduction of TiB2 forms the SiC–TiB2 grain boundary with lower barrier height, which allows electrons to pass through more easily. Therefore, the nonlinear coefficient and the resistivity of SiC–TiB2 composite ceramics both gradually decrease with the increase of TiB2 content. When the TiB2 content reaches 15 vol%, the electrical percolation property is obtained, and the bulk resistivity drops to 0.87 Ω cm. The infrared emissivity of the composites shows a decreasing tendency, which is not conducive to practical application. According to the results of electrical and infrared radiation properties, the addition amount of 15 vol%TiB2 is a better formula.