Aluminium-induced modulation of reaction kinetics and polytype formation in silicon carbide synthesized through high-energy ball milling

Abstract

Silicon carbide (SiC) is a versatile material employed in a broad range of applications, including abrasives, power electronics, and emerging quantum technologies. It is widely recognized as a high-performance technical ceramic, owing to its good thermal conductivity, high hardness, and chemical stability. Cost-effective strategies for synthesizing SiC with application-specific properties are thus highly desired, stimulating the development of numerous approaches to produce high-quality products. Direct synthesis of SiC from elemental silicon and carbon offers precise control over crystal size and phase purity at temperatures lower than those required for the reaction between SiO₂ and carbon. Nonetheless, further reductions in reaction temperature are desired to enhance both cost- and energy efficiency. This study explores the combined effects of high-energy ball milling, combustion synthesis, and aluminium addition on the formation of SiC. Both the precursors and the resultant products were comprehensively characterized to elucidate the influence of these processing methods. The results indicate that aluminium, in the studied 0–20 mol% concentration range, reduces the reaction time and increases the prevalence of hexagonal inclusions. In contrast, wet high-energy ball milling demonstrates only a marginal mechanical activation effect, which contradicts the previous results of dry milling. Furthermore, the oversaturation threshold (5 mol% Al in SiC) critically impacts both the synthesis process and the resulting material properties, thereby demonstrating the importance of composition control during synthesis.