Publication

Abstract : In this work, AA7050 aluminum alloy reinforced with B4C particles of average particle size 25 µm is examined. The composites are invented by varying the weight percentage of B4C particles in the liquid stir casting route. K2TiF6 is added as a flux to overcome the wetting problem between B4C and molten aluminum alloy. The influence of reinforcement, sliding velocity, sliding distance, and of applied load on the wear rate is studied using a pin-on-a disc equipment in experiments. Optical, scanning electron microscopy, and EDX analysis are performed to characterize the samples. The influence of high-temperature spark produced during electric discharge machining on composite materials was analyzed. The Rockwell hardness tests were compared on as cast worn and electric discharge-machined surfaces. The hardness of the composites increases, whereas the coefficient of friction decreases with addition of B4Cp. The hardness value of a worn surface was higher than as cast composites in all cases due to the presence of a ferrous metal, with its presence being confirmed by energy dispersive X-ray analysis. The hardness value of the electric discharge-machined surface of composites was lower than unreinforced aluminum alloy due to the increase in the gap distance. There is an improvement in wear resistance due to the forming of a tribo-rich mechanically mixed layer. The presence of iron and oxygen in the worn surface confirmed the MML and oxidation reaction. The B4C-reinforced composites show better wear resistance than a pure aluminum alloy.