Study on Inducing Synthesis and Growth Mechanism of β-SiAlON Whisker

β-SiAlON whiskers were synthesized from β-SiAlON powder(inducing seed),SiC(basal body),Si powder,Al powder and Al2O3 powder.The microstructure,compositions of β-SiAlON whiskers and mechanical property of β-SiAlON/SiC composite were detailed discussed,and the growth mechanisms of β-SiAlON whiskers based on thermodynamic analysis were subsequently developed in this paper.The results shows that(1)the addition of β-SiAlON seed is beneficial to formation of β-SiAlON whisker,and the vapor-liquid-solid(VLS) and vapor-solid(VS) mechanisms could be adopted to explain the behavior of whiskers growth;(2)while the β-SiAlON whiskers grows in VLS mechanisms,the diameter of rodlike and fibrous wiskers is the range of 200-300 nm and the z value of β-SiAlON whisker is about 1.56;whereas in VS mechanisms,the diameter of rodlike and bamboo-like whiskers with well-developed crystalline is the range of 0.5-1.5 μm and the z value is about 1.76;(3)β-SiAlON whisker has improved the fracture strength of β-SiAlON/SiC composites,the higher flexural strength(55.2 MPa) can be obtained from the composites with many whiskers and in higher porosity(32.1%).