Oxide-bonded silicon carbide and alumina ceramics obtained from template SCS powders

Abstract

This study explores the synthesis of SiC@Al₂O₃ and Al₂O₃@Al₂O₃ core-shell structured powders using a template-assisted solution combustion synthesis (SCS) method. Employing urea as the sole fuel resulted in well-dispersed aluminum oxide particles on the silicon carbide surface, while mixed fuels led to agglomeration. Subsequent processing using the template SCS method effectively minimized agglomeration and yielded predominantly the δ-Al₂O₃ phase. Despite not completely preventing silicon carbide oxidation, the core-shell structures significantly enhanced mullite bond formation, leading to reduced porosity and improved mechanical properties. The SCS method also lowered the mullite synthesis temperature to 1335 °C. Cold isostatic pressing further increased density and mechanical properties, resulting in microhardness of 5.2 GPa and bending strength of nearly 50 MPa. Template SCS emerges as a promising technique for producing high-density, high-performance ceramics and composite materials at lower temperatures.