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

Abstract

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.