Alumina Coating on Carbon Fibers by Sol-Gel Method

Alumina precursor film was coated on carbon fibers by a sol-gel method using aluminum alkoxide solution. The optimum coating condition for the concentration of alumina alkoxide and silane coupling agent was determined to uniformly coat alumina precursor on carbon fibers. Alumina precursor converted to alumina ceramics by heating at 750℃. SEM and EPMA showed that alumina ceramics was uniformly coated on carbon fibers. The thickness of alumina layer increased with increasing coating times. The crack and uneven surface was observed on alumina layer when the thickness was over 0.8 μm. Tensile strength of carbon fibers coated by alumina ceramics was higher than that of original carbon fibers