Studies on the performance of Metal Matrix Composites (MMC)

Abstract

The role of engineering materials in the development of modern technology need not be emphasized. As the levels of technology have become more and more sophisticated, the materials used also have to be correspondingly made more efficient and effective. The increasing use of Aluminium alloy materials in structural and space applications generated considerable interest for the development of techniques to predict the response under various operational conditions. Metal Matrix Composites (MMC) are relatively new materials and are used extensively in different fields such as automobile, aerospace, etc. Among metal matrix composite materials, particle reinforced MMCs are increased applications due to their very favorable properties, including high mechanical properties and good wear resistance. These composites are potential structural material for aerospace and automotive applications. Silicon Carbide particulate reinforced aluminum (SiCp-Al) composites possess a unique combination of high specific strength, high elastic modulus, good wear resistance and good thermal stability than the corresponding non-reinforced matrix alloy systems. Aluminium silicon carbide reinforced metal matrix composite has tremendous application in automobile, aerospace and other industries due to their excellent properties. Aluminum Metal Matrix Composites initially replaced Cast Iron and Bronze alloys but owing to their poor wear and seizure resistance, they were subjected to many experiments and the wear behavior of these composites were explored to a maximum extent and were reported by number of research scholars for the past decades. The acceptance of particulate Metal Matrix Composites (MMCs) for engineering applications has also been hampered by the high cost involved in producing components. Although several technical challenges exist in the casting technology yet it can be used to overcome this problem. One of the major challenges is the uniform distribution of reinforcement within the matrix, which directly affects the properties and quality of composite material. In the present work a modest effort has been made to develop Aluminium based Silicon Carbide particulate MMCs with two main objectives. i) To develop a low cost technique of producing MMCs. ii) To obtain homogenous dispersion of reinforcement material. To achieve the above said objectives Mechanical alloying method of Powder Metallurgy has been adopted. Powder Metallurgy (P/M) is an ideal method of fabrication for MMCs because of the ability to produce near net shapes and little material waste associated with the process. Mechanical alloying of powders resulted in improvement in hardness and compressive strength of Al-SiCp composites. In this work a 23 full factorial design of experiments (DOE) was used to collect experimental data to statistically analyze the effect of the process parameters on the hardness, density, forgeability etc. of the sintered Al-SiCp composites using RSM .Three factors central composite design is employed for carrying out this work. Analysis of variance is used for checking the validity of the model. Optimum conditions for better mechanical properties are determined using desirability function approach. The influences of different parameters in mechanical properties Al-SiCp particulate composite have been analyzed in detail. The predicted values and measured values are fairly close, which indicates that the developed model can be effectively used to predict the better mechanical properties of Al-SiCp. The effect of weight percentage of silicon carbide on hardness of composites was investigated by using Vickers hardness Test. It was observed that the distribution of silicon carbide particles was uniform. Other published work was also compared and found to be in very good correlation with the predicted result. Keywords: Metal matrix composites, Response surface method, Design of experiment, Central composite design. Al-SiCp particulate composites, Mechanical characterization, Mechanical alloying, Microstructural analysis, Powder metallurgy.