Synthesis, growth mechanism, and performance of in-situ catalytic growth Al4SiC4 whiskers in Al2O3-SiC-C refractories

Ceramic whiskers exhibit excellent performance due to their special structure, making them widely used in the field of refractories. In this work, a novel Al4SiC4 whisker was designed to improve the mechanical properties and thermal shock resistance of Al2O3-SiC-C (ASC) refractories. By introducing nickel nitrate as a catalyst, the Al4SiC4 whiskers with a special "stalactite" structure could be directly grown in situ at the operating temperature of ASC (1450 °C). Combining the experimental results and first-principles calculations, the AlNi2Si alloy formed during the heat treatment process acted as catalyst sites, AlO, SiO and CO were easily absorbed on the Ni55 surface. Subsequently, the Al-O, Si-O and C-O bonds were broken and reacted with each other to grow Al4SiC4 whiskers according to the vapor-liquid-solid mechanism. As expected, the incorporation of Al4SiC4 whiskers resulted in a 57.4% increase in cold compressive strength (CCS) and a 47.2% increase in residual strength ratio (RSR) of the ASC refractories due to the strengthening mechanism of whisker bridging. This study presents a novel research strategy for enhancing the properties of refractories.