Effect of PyC coating on mechanical properties of Cf/AZ91D composites

The microstructure of high strength PAN-based T700 carbon fibre (C-f) with pyrolytic carbon (PyC) coating was characterised. Effects of PyC coating on the surface of carbon fibres, interface characteristics, and mechanical properties of C-f/AZ91D composites were evaluated. The results showed that the carbon fibres with PyC coating had higher surface roughness and higher graphitisation which were beneficial to ease hazardous interface reaction. C-f-PyC/AZ91D composites with an optimal PyC coating that is about 150nm thick and has low texture exhibited ultimate tensile strength of 416MPa, which demonstrated 35% improvement compared with the C-f/AZ91D composites. The increase of mechanical properties of C-f-PyC/AZ91D composites could be ascribed to a synergistic effect of the rough C-f surface interlocking, an optimum interfacial bonding between fibres and matrix, and protection of fibres from a corrosive attack of the aluminium element in the matrix.