Progress in fabrication and characterization of mullite whiskers

Abstract

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.

Shape‐controllable synthesis of mullite whisker and its effect on tribological behavior of resin‐based friction materials

“…The phase purity of all the samples was at a high level and showed no obvious difference, which indicated pure mullite phase was obtained through this sol–gel process. Moreover, the use of AlF 3 was mainly used to generate a gas phase during the whisker synthesis reaction, which promoted mullite crystal nucleus fast growth along the C axis forming a large number of whiskers 27–29 . In other words, AlF 3 can change the aspect ratio, but did not impact the phase structure of the mullite products.…”

“…Moreover, the use of AlF 3 was mainly used to generate a gas phase during the whisker synthesis reaction, which promoted mullite crystal nucleus fast growth along the C axis forming a large number of whiskers. [27][28][29] In other words, AlF 3 can change the aspect ratio, but did not impact the phase structure of the mullite products.…”