Effect of particle size on mechanical properties and tribological behaviour of aluminium/fly ash composites

In the present study, aluminium alloy (A380) composites containing 3, 6, 9 and 12 weight percentage of fly ash particles were fabricated by liquid metallurgy technique. Three different size ranges of fly ash particles (50-75 mu m, 75-103 mu m and 103-150 mu m) were used. The composites were evaluated for hardness, tensile strength, density, dry sliding wear and frictional behaviour. Pin-on disc apparatus was used to conduct wear tests at loads of 20, 30 and 40 N at a sliding speed of 3 m/s for a constant period of 10 min. Results showed that hardness, ultimate tensile strength, wear resistance and coefficient of friction were superior in composites reinforced with coarse fly ash particles (103-150 mu m) compared to composites with fine particles. The hardness, ultimate tensile strength and wear resistance increased, whereas the coefficient of friction and density decreased with the increase in weight percentage of fly ash. Wear resistance and coefficient of friction decreased with increase in applied load. Scanning electron microscope investigations of worn-out samples were carried out to study the progress of wear.