Experimental investigations on analysis of variance analysis of hardness and thermal conductivity of AL7475 reinforced silicon nitride and graphite

This study investigates the mechanical and tribological behavior of Al7475-based metal matrix composites (MMCs) reinforced with varying proportions of silicon nitride (Si₃N₄) and graphite (Gr), developed through stir casting.The present study highlights the beneficial impact of graphite and Si 3 N 4 reinforcement on the Al7475 wear performance to determine the hardness and thermal conductivity of the composites.This study examines Al7475based MMCs reinforced with 3-12% Si₃N₄ and graphite via stir casting.The optimal 5% Si₃N₄-5% Gr hybrid composite achieved superior Hardness (74.1) and the Thermal conductivity for 5% Si₃N₄-5% Gr is 242.7 W/ (m°C).Microstructural analysis revealed that the inclusion of Si₃N₄ improved grain refinement and hardness, while graphite contributed to enhanced lubrication and wear resistance.SEM/EDS confirmed uniform dispersion, while fractography revealed a ductile-to-brittle transition with higher reinforcement.ANOVA (R² > 89% for Thermal conductivity, > 98%) validated reinforcement significance, highlighting that optimal ratios enhance performance, whereas excess causes agglomeration and reduced ductility.The findings confirm that an optimal hybrid reinforcement ratio effectively enhances mechanical strength and thermal conductivity, while excessive reinforcement leads to agglomeration, reduced ductility, and inferior performance.