STUDY OF HIGH VELOCITY OXY FUEL COATINGS WITH DIFFERENT MATERIALS

Abstract

This study investigates the enhancement of mechanical and tribological properties in Aluminium Metal Matrix Composites (AMMCs) reinforced with Rice Husk Ash (RHA) and Groundnut Shell Ash (GSA), focusing on their application in high-performance automotive components such as piston rods and crankshafts. The incorporation of RHA and GSA in AMMCs improves wear resistance, oxidation protection, and cost-effectiveness, while maintaining strength and lightness. Additionally, High-Velocity Oxygen Fuel (HVOF) thermal spraying of tungsten carbide-cobalt-chromium (WC-CoCr) coatings significantly enhances the wear and corrosion resistance of these composites. The WC-CoCr coating increases the microhardness, reduces the coefficient of friction, and provides long-term protection against corrosion, making it suitable for demanding applications in harsh environments like marine and automotive conditions. Experimental results reveal that the combination of AMMCs with RHA and GSA, coupled with WC-CoCr coatings, offers a promising solution for sustainable, high-performance materials. The results showed that the WC-CoCr coatings significantly increased the microhardness of AMMCs, with the highest value observed in composites containing 10% by weight of RHA and GSA, enhancing wear resistance for high-friction applications such as piston rods and crankshafts. Surface roughness was found to increase with reinforcement content, affecting coating adhesion and wear behaviour. Coefficient of friction tests revealed a substantial reduction in friction for WC-CoCr-coated AMMCs (0.125) compared to uncoated composites (0.3375). The presence of RHA and GSA influenced friction under varying conditions, while the Signal-to-Noise (SN) ratio analysis indicated complex interactions between reinforcement, sliding speed, and applied load. After 1250 hours of accelerated salt spray testing, the WC-CoCr coatings provided effective corrosion protection, with minimal corrosion damage to the aluminium substrate. These findings demonstrate that WC-CoCr-coated AMMCs with RHA and GSA offer superior wear and corrosion resistance, making them a promising solution for demanding automotive and marine applications. The study highlights the importance of surface conditions, reinforcement composition, and optimal HVOF spraying parameters for achieving superior tribological and mechanical properties. This approach not only improves material performance but also promotes eco-friendly manufacturing by utilizing agricultural by- products.