Metal matrix composites (MMCs) are of great interest in industrial applications for lighter materials with high specific strength, stiffness and heat resistance. The processing of MMCs by casting process is a very promising way of manufacturing near net shape composites at relatively low cost. The liquid metallurgy squeeze casting technique has characteristics such as fine microstructure as a result of rapid cooling, low porosity and good bonding between the particles and base alloy. In this study, the effect of hardness, tensile, compression and impact properties as well as density have been investigated. The Al-4.5wt%Cu alloy was chosen as base matrix casted by both stir and squeeze casting. Fly ash is one of the most inexpensive and low density reinforcement available in large quantities as solid waste is used as reinforcement. The Al-4.5wt%Cu reinforced 3, 6, 9 and 12wt%fly ash composite was squeeze casted with an applied pressure of 120MPa. The results showed that hardness tensile compression and impact values were increased by increasing weight percentage of fly ash reinforcements during squeeze casting. Porosity and other casting defects such as shrinkage cavities were minimised due to pressure applied during solidification. Increase in weight percentage of fly ash composites caused to increase porosity even in squeeze casting but lesser than gravity cast matrix alloy. Microstructure shows the absence of micro porosity, and grain refinement interfacial bond between matrix and reinforcement.

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Relative movement between piston and cylinder of an IC engine contributes to more than 60% of the friction experienced by the engine - in turn contributing to the wear of the piston and hence loss in its operational performance and efficiency. It is pertinent to explore technological solutions to overcome this situation. Texturing of surfaces appears to be an useful technique to enhance the tribological performance of the piston and cylinder assembly and information about the same are available in published literature. Laser surface texturing of a typical piston material such as an eutectic Al-Si alloy employing high power CO2-CW laser, firstly to examine the magnitudes of optimum laser processing conditions to realize surfaces which can retain oil and secondly to carry out characteristic analysis of the surface quality of the test material subjected to laser texturing, constitute the main thrust of this work. Measurements and analysis of the areal roughness parameters on the laser textured surfaces of the samples on a con-focal microscope reveal their capacity for enhanced oil retention, in turn ensuring reduced chances of scuffing of the sliding surfaces in comparison with non-textured samples, examined under similar test conditions.

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