MECHANICAL AND TRIBOLOGICAL EVALUATION OF ALUMINUM METAL MATRIX COMPOSITE PIPES FABRICATED BY GRAVITY AND SQUEEZE STIR CASTING

Aluminum metal matrix composites (MMC) find many industrial applications due to its high strength, zero corrosion, light weight and durability. In this work, gravity stir casting and squeeze stir casting were used to produce MMC solid rods of length 21cm. LM25 grade, from scrap alloy wheel of car, was used as matrix and Alumina was added as reinforcements to improve the composite properties. The performed microstructure analysis showed a greater percentage of porosity for gravity casted samples. Brinell hardness tests recorded 61 and 56 for squeeze and gravity stir casting respectively. The analysis was further strengthened by conducting tensile test, compression test, abrasion and erosive wear tests on the casted pipe sections. Optical Microscopy images of squeeze casted Al MMC's shows a homogenous and a condensed LM25 matrix with alumina reinforcements even at high abrasion rates. Squeeze casted samples exhibited higher hardness, tensile and compression strengths and wear resistance by keeping stirring time, and stirring speed constant. Squeeze stir casting was suggested for the production of Aluminum MMC pipes.