Aluminum oxide/amorphous carbon coatings on carbon fibers, prepared by pyrolysis of an organic-inorganic hybrid precursor

A formation of organic-inorganic hybrid precursor, polyvinyl butyral (PVB)/alumina sol, was investigated to make high quality coating on carbon fiber. Acetylacetone (AcAcH) was used to avoid the undesirable precipitation of gelatinous aluminium hydroxides during hydrolysis of aluminum-iso-propanol (Al(PrOi)(3)). The mole ratio of hydroxyl group of PVB and Al(PrOi)(3) leading to transparent cracked-off pyrolytic hybrid film was studied. Use of the hybrid precursor allows for easy dip coating on fibers continuously for obtaining aluminium oxide and amorphous carbon coatings simultaneously after pyrolysis. The fiber with the hybrid coating demonstrates a better oxidation resistance up to 700 degreesC as compared with that coated by pure alumina sol. Significant improvement of mechanical performance was observed for aluminium matrix composite reinforced by the hybrid coated fibers (5% PVB), that is counted by the proper fiber pull-out behaviour. Such coating also exhibits some promise in ceramic matrix composites. (C) 2001 Elsevier Science B.V. All rights reserved.