Progress in fabrication and characterization of mullite whiskers

Mullite has an orthorhombic crystal structure, with various advantages, such as high mechanical strength, and stable chemical and physical properties. Especially, mullite whiskers have been widely acknowledged to be potential candidates as reinforcing elements in the fabrication of ceramic-matrix composites. Various strategies have been developed to synthesize mullite whiskers, such as catalytic methods, liquid-phase reaction, molten salt reaction, solid-state reaction and high-energy ball milling process. In different synthesis methods, the underlying mechanisms governing the anisotropic grain growth of mullite grains vary. This paper aims to offer an overview on the progress in fabrication of mullite whiskers with different methods, and the perspectives on these special materials are briefly discussed.