| Wear characteristics of 7075 Al/SiC_p composites fabricated by spray forming and extrusion process are studied. This study shows a wear transition from mild to severe wear as a function of applied load, sliding velocity and friction temperature with wear mapping approach. 7075 Al/SiC_p composites exhibit the transition from mild to severe wear when a load, sliding velocity or temperature reaches a critical value respectively. In mild wear regime; wear rate increases with increasing applied load. But wear rate decreases with increasing sliding velocity. At constant load and velocity in mild wear conditions, wear rate decreases with increasing friction temperature. The reasons are that the worn surface of disk was covered with much more iron oxides at elevated temperatures than at room temperature which played a role as solid lubricant. But in severe wean regime, this oxide layer is not stable and fractured, leading to increase wear rate and friction coefficient. Wear transition map of 7075 Al/SiC_p composites is constructed on applied load and sliding velocity axes with elevated temperatures. Severe wear regime is enlarged with increasing temperature on the wear transition map and wear transition conditions move to lower load and velocity at elevated temperatures than at room temperature. Therefore safe operating range of aluminum metal matrix composite parts is reduced at elevated temperatures. |
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