The Effect of Short Fiber-Orientation on Dry Sliding Friction and Wear Properties of Al_2O_(3f) C_f/ZL109 Hybrid Composites

Al 2O 3f C f/ZL109 short fibers reinforced hybrid metal matrix composites were fabricated by squeeze casting.The effect of fiber-orientation on the dry sliding friction and wear properties of the hybrid composites at a load of 196 N and sliding velocity of 0.837 m/s was investigated on a MM-200 test rig by using statistical research method.The results show that the wear rate and coefficient of friction of the hybrid composites with both parallel-and normal-oriented fibers have normal distribution of probability density.The normal distribution functions of the wear rates are of identical variance,but the hybrid composites with parallel-oriented fibers has greater average wear rate.The normal distribution functions of coefficient of friction are also of identical variance,but the hybrid composites with parallel-oriented fibers has smaller average value.Fiber normal-orientation is benificial to improving the wear-resistance of the composites but leads to greater coefficient of friction.This is because more and larger microcracks are prone to generate and propagate on the worn surface of the hybrid composite with parallel-oriented fibers, while more carbon fibers are liable to be smashed into fine particles and contribute to reduce friction in this case.The hybrid composites with either parallel-or normal-oriented fibers are both characterized by ploughing in sliding against steel.The key to the influence of fiber-orientation on the friction and wear properties of the composites lies in that whether the fiber can effectively prevent the generation and propagation of microcracks and the peeling rate of the reinforcement from the matrix.