Wear properties of 7075 Al alloy/SiCP composite (I); -wear behaviour at room and elevated temperature

摘要

Wear characteristics of 7075 Al/SiCp compositesfabricated by spray forming and extrusion process are studied. Thisstudy shows a wear transition from mild to severe wear as afunction of applied load, sliding velocity and friction temperaturewith wear mapping approach.7075 Al/SiCp composites exhibit the transition from mild tosevere wear when a load, sliding velocity or temperature reaches acritical value respectively. In mild wear regime, wear rate increaseswith increasing applied load. But wear rate decreases withincreasing sliding velocity. At constant load and velocity in mildwear conditions, wear rate decreases with increasing frictiontemperature. The reasons are that the worn surface of disk wascovered with much more iron oxides at elevated temperatures thanat room temperature which played a role as solid lubricant. But insevere wear regime, this oxide layer is not stable and fractured,leading to increase wear rate and friction coefficient. Weartransition map of 7075 Al/SiCp composites is constructed onapplied load and sliding velocity axes with elevated temperatures.Severe wear regime is enlarged with increasing temperature on thewear transition map and wear transition conditions move to lowerload and velocity at elevated temperatures than at roomtemperature. Therefore safe operating range of aluminum metalmatrix composite parts is reduced at elevated temperatures.