PROCESSING AND CHARACTERIZATION OF ALUMINIUM BASED COMPOSITES REINFORCED WITH STEEL AND GRAPHITE PARTICULATES

Abstract

In this research, the microstructural analysis mechanical properties, wear, damping and corrosion behaviour of Aluminium matrix composites reinforced with steel and graphite particles was investigated. Steel and graphite particles with size range of 100 μm and 50 μm respectively were utilized to develop stir cast aluminium matrix composites having 4, 6 and 8 wt. % of the steel particulates, and 7 wt.% steel + 1 wt.% graphite, 6 wt.% steel + 2 wt.% graphite as reinforcement. Unreinforced aluminium and 8 wt. % Silicon Carbide (SiC) reinforced aluminium matrix composites were also prepared for control experimentation. The result shows that the composites have generally low porosity, less than 1.5%. The hardness of the composites increases (approximately 19 % increase) with an increase in steel particles content in the reinforced composites. The difference in ultimate tensile strength between the 8 wt.% SiC containing composites and that containing only steel particles is within the range 3.2 – 24 % for the 4 to 8 wt.% steel particles reinforced composites. It is observed that the composite compositions containing only steel or steel and graphite particles, had specific strength higher than that of the composite containing 8 wt. % SiC. Compared with the 8 wt. % steel reinforced composite, there is approximately 9 % increase in specific strength. The fracture surfaces of all the steel reinforced composites were essentially rough, a preponderant feature of ductile fracture mode. The wear rate of the composites was generally low indicating good wear resistance. The control composite composition with 8 wt. % SiC, was observed to have the highest damping capacity. Finally, the steel and graphite particles reinforced aluminium alloy based composites were generally more corrosion resistant in 0.3M H2SO4 solution compared with the SiC reinforced aluminium alloy. The results demonstrate the capacity of steel and graphite particles to serve as a reliable and cost effective reinforcement material for AMCs with improved mechanical properties, wear, and corrosion performance which are required in several automobile engine components.