Synthesis of β-SiAlON Whiskers from Pyrophyllite

Abstract

Synthesis of β-SiAlON whiskers from pyrophyllite was investigated and the growth of the whiskers was explained by VLS (vapor-liquid-solid) mechanism. During heating, Fe2O3 in pyrophyllite was reduced by carbon derived from resin to Fe which further reacted with C to form an alloy (FexCy). When the temperature was above the melting point of the alloy (about 1153°C), the alloy would become a liquid droplet under the influence of surface tension. Once the droplet was formed, the gases such as Si(g), SiO(g), Al(g), Al2O(g) and N2(g) would dissolve into the droplet. When the liquid droplet became supersaturated with the gases, the whiskers would grow by precipitation of β-SiAlON from the liquid.