Improving thermal stability of SiC whiskers via nanoscale Ti₃SiC₂ coatings

Abstract

Effects of SiC whiskers (SiC w ) on the mechanical properties of composites largely depend on their thermal stability at high temperature. In this study, pure SiC w and Ti 3 SiC 2 coated SiC w were thermal treated at 1600-1800 • C for 1 h. Their phase assemblage, morphology, and structural evolution were investigated. Oxygen partial pressures in the graphite furnace resulted in the breakdown of SiC w into particles at 1600 • C, and the degradation became more pronounced with temperature increasing. The thermal stability of SiC whiskers at 1600-1700 • C was significantly improved by a thin Ti 3 SiC 2 coating on them, as both thermodynamic calculations and experimental observations suggest Ti 3 SiC 2 coating could be preferentially oxidized/decomposed, prior to the active oxidation of SiC. At 1800 • C, the protective role of the coating on the whiskers became weakened. SiC was converted into gaseous SiO and CO, with the remaining of interconnected TiC micro-rods and amorphous carbon.

Analytical model for strength of MAX phases considering high‐temperature oxidation and plastic deformation

“…The high‐temperature strength plays a vital role in determining the reliability and service life of MAX phases 5–7 . Moreover, it has been proven that high‐temperature oxidation significantly affects the strength of MAX phase 8–10 . Therefore, revealing the key factors that control the strength and quantitatively characterizing their evolution with temperature is critical and essential for the preparation, application, and safety assessment of MAX phase materials.…”