Application of plasma electrolytic oxidation method on Al/Al2O3 metal matrix composite materials

Separation of reinforcements under the effect of force and heat in ceramic reinforced aluminium matrix composites produced by powder metallurgy shortens the wear lifespan of Al-MMCs. In this thesis, Al samples and Al matrix composites containing, 5% and 10% Al2O3 ceramic particles were produced by powder metallurgy. Plasma electrolytic oxidation (PEO) treatment was applied to the samples. A current density of 20 A/dm2 and duration of 30 min were determined for the process. 1 g/l KOH and 7 g/l Na2SiO3 solution were used as the electrolyte. Scanning electron microscope (SEM) images were taken for visual characterization of the samples and EDS analysis was performed where necessary. Hardness measurements were made by micro Vickers method with 2 kg load applied to the sample surface. The specimens were subjected to a wear test at a speed of 0.5 m/s under a force of 10 N in a pin-on-cylinder test apparatus. Simultaneous force measurements and friction coefficients were determined during the test. Wear loss values were determined by mass measurement. As a result of the characterization and wear tests, it was found that the reinforcement particulate content ruined the coating homogeneity but contributed positively to the abrasion resistance by increasing the strength of the substrate material.