The significance of the fibre coating in the production of carbon fibre-reinforced carbons from ht carbon fibres and phenolic resin as matrix precursor II. Phenolic resin coatings Original Research Article

Commercially surface-treated HT carbon fibres were coated with phenolic resin in order to reduce the adhesion of the phenolic resin matrix to the fibre surface. Unidirectional (UD) composites were fabricated using uncoated and coated fibres and a standard phenolic resin as matrix: the fibre volume fraction of the green composites was 60 vol%. The composites were carbonized at 1000 C and treated at 2100 C. The effect of the coating was examined by measuring mechanical properties and analyzing failure modes after curing, carbonization, and treatment at graphitization temperatures. The effectiveness of a phenolic resin coating of optimum thickness was demonstrated by the flexural strength after each processing step (values obtained without the coating are given in parentheses): after curing 2300 M Pa (1000 M Pa): after carbonization 400 M Pa (260 M Pa): after graphitization treatment 800 M Pa (575 M Pa).