Mullite fibres prepared by sol–gel method using polyvinyl butyral

Mullite fibres with uniform diameter and smooth surface have been synthesized using commercial grade polyvinyl butyral (PVB) as binder. The sol with good spinnablity was obtained at reaction temperature of 60 °C for 1 h. The results of X-ray diffraction indicated that the Al–Si spinel was obtained before complete mullization, which implied the addition of PVB retarded the phase transformation of mullite. The fibres showed a rough surface and lateral cracks at 800 °C. Smooth and dense surface was observed when fibres were sintered at 1200 °C and completed transformation to mullite was achieved. This technique offered the possibility of synthesizing mullite fibres at considerably lower cost than at present.