Effect of fibre-orientation on friction and wear properties of Al2O3 and carbon short fibres reinforced AlSi12CuMgNi hybrid composites

Al2O3 and carbon short fibres reinforced AlSi12CuMgNi hybrid composites were fabricated by preform squeeze-infiltrated route. Fibres distribution and microstructure of matrix in the composites were observed. Moreover, the effect of fibre-orientation on dry sliding friction and wear properties of the hybrid composites were determined by statistical analysis under the condition of 196 N load and sliding velocity of 0.837 m/s. Al2O3 and carbon short fibres distribute uniformly and exhibit a quasi-two-dimensional random orientation in the composites. The statistical analysis results show that average value of wear rate in parallel-oriented wear surface of the hybrid composites is greater than that in normal-oriented wear surface. Whereas the statistical average value of friction coefficient in parallel-oriented wear surface is less than that in normal-oriented wear surface. Fibre normal-orientation contributes to improve wear property of the composites. The dominant wear mechanisms of the hybrid composites in parallel- and normal-orientation are ploughing groove and delamination wear. There are more and wider microcracks in parallel-oriented worn surface than in normal-oriented worn surface. The worn surface in fibres normal-orientation is smoother than that in parallel-orientation. The key to the effect of fibre-orientation on friction and wear properties lies in that whether fibres can inhibit effectively the nucleation and propagation of microcracks in subsurface and the degree of delamination wear.