Coating of Alumina Fibres With Aluminium Phosphate by a Continuous Chemical Vapour Deposition Process†

Abstract

We developed aluminium phosphate-coated alumina fibres with significantly improved pull-out properties, which may be suitable for reinforcing advanced inorganic composites qualified for operating temperatures up to 1200 °C. Aluminium phosphate layers are generated on the surface of alumina fibres using a continuous chemical vapour deposition (CVD) process: At furnace temperatures between 850 °C and 1050 °C, within a tube reactor heated by an electrical furnace, the alumina fibres are exposed to gas mixtures of phosphoryl trichloride and oxygen, inducing dense aluminium phosphate layers on the fibre surface. Mini-composites were prepared by embedding the coated fibres into an alumina matrix.