Observations on the appearance of fatigue in carbon fibre/aluminium composites during sliding wear

The damage done to carbon fibre reinforced aluminium (C/Al-composite) by sl iding wear was investigated in a series of experiments carried out on a sli ding wear test equipment operating on the "cylinder-on-disc" principle. The defects produced may indicate that this type of wear results in fatigue wi thin the surface regions of the material. The examination of transverse cro ss sections of the C/Al-composites confirmed the presence of this type of d amage at a depth of 10 to 40 mu m from the specimen surface. Both pores and cracks were found within the aluminium matrix, only a few 100 nm from the fibre-matrix interface, to which the cracks ran parallel. It is possible th at the carbide needles present behave as obstacles to the movement of dislo cations. Increasing wear was observed to result in the formation of pores w hich in turn cause further material damage.