Review of VLS SiC Whisker Growth Technology

In situ Growth of SiC Whisker in Pyrolyzed Monolithic Mixture of AHPCS and SiC

“…4,5 Despite the large variety of techniques that exist for growing SiC whiskers, most of them can be described by vapor-liquid-solid (VLS) 6,7 and vapor-solid (VS) 8 mechanisms. The VLS mechanism involves the use of liquid catalysts (e.g., iron) to act on the whisker tip to absorb silicon and carbon species from the surrounding gases to grow whiskers at the interface between the liquid catalyst and SiC crystal.…”

“…Because of its potential as a reinforcement material for ceramics, SiC whiskers have been prepared by various techniques, such as crystallizing the whiskers from liquefied SiC under high temperature and pressure, 2 pyrolyzing the fibrous polymer precursor of SiC, 3 and reacting SiO with graphite or rice husk at high temperature. 4,5 Despite the large variety of techniques that exist for growing SiC whiskers, most of them can be described by vapor-liquid-solid (VLS) 6,7 and vapor-solid (VS) 8 mechanisms. The VLS mechanism involves the use of liquid catalysts (e.g., iron) to act on the whisker tip to absorb silicon and carbon species from the surrounding gases to grow whiskers at the interface between the liquid catalyst and SiC crystal.…”

Engineering Scale Development of the Vapor-Liquid-Solid (VLS) Process for the Production of Silicon Carbide Fibrils

“…The basic process chemistry has been described in more detail elsewhere [7,8]. Figure 1 shows a schematic of reaction mechanisms for the process.…”

“…The thermodynamics of the reactant gas and liquid catalyst droplet have been described elsewhere [8,9]. Order of magnitude calculations have been used to postulate potential rate limiting steps in the fibril growth process [7]. SiO and CH 4 delivery appeared to be the probable rate limiting mechanisms.…”

“…Figure 2 is a reactor design schematic diagram. Process gas containing H2/N2/CO/CH4 [7 ] is introduced at the base of the reactor and flows in vertically rectangular channels. SiO is produced in-situ at locations termed generators [4].…”