Effects of ZnO addition on the microstructure/corrosion, wear and mechanical properties of sintered Mg-Al matrix composites

Abstract

Magnesium (Mg)-based composites offer outstanding properties, which make them suitable materials for various applications in medical, aerospace and energy sectors, among others. The wide applications of Mg-based composites have attracted continuous effort to increase their properties and performances. Therefore, the present work focused on synthesizing magnesium-aluminium-zinc oxide (Mg-Al-ZnO) composites. Mg-3Al-xZnO (x = 3, 6 and 9 wt%) composites were prepared using powder metallurgy (PM) route. The composite powders and sintered composites were analyzed to determine their microstructures, using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis. In addition, the sintering process took place in argon atmosphere at 450 °C. The quantitative analyses of density, porosity, hardness, compressive strength (CS) and corrosion rate (CR) of the composites were performed. Wear performance was also studied with various wear control parameters, such as the sliding velocity (V), sliding distance (D), applied load (P) as well as ZnO content. Pin-on-disc apparatus was used to determine the wear rate (WR) and coefficient of friction (COF) of the innovatively prepared Mg-3 wt%Al-ZnO composites. The experimental study was conducted in accordance with Taguchi's L16 orthogonal design. Signal-to-noise (S/N) ratio analysis was employed to determine the best combination of parameters for WR and COF. Summarily, SEM images confirmed that ZnO particles were uniformly distributed in the composite samples. Statistical technique, called analysis of variance (ANOVA), was adopted to find the significant factor which affected WR and COF. The P significantly affected the WR, followed by the inclusion of ZnO. But, with respect to COF, ZnO reinforcement inclusion affected COF significantly when compared with the P. Both V and D did not affect WR and COF. Hence, the application of the various composite samples should depend on their various responses to friction and wear, especially in working conditions where both quantities are inevitable.