Investigation of Mechanical and Machining Characteristics of Aluminium Metal Matrix Composites

Abstract

Successes of all industries like automotive, aerospace, marine and electronics newlineapplications are mainly depends of reducing weight and at the same time increase in newlinelife, millage and appearance of their products. It mainly depends on developing new newlineand cost effective materials that have high weight to strength ratio, bio degradable and newlineat the same affordable. Hence, composite materials have grown steadily, penetrating newlineand conquering new markets. Generally composite materials constitute a significant newlineproportion of the engineered materials market, ranging from everyday products to newlinesophisticated applications. newlineIn the present research, the fabrication and testing the mechanical properties of newlineMono and Hybrid Composites are reported by using Aluminium as matrix material newlinewhile Alumina and Tungsten Carbide as reinforcements. Here, three categories of newlineAluminium Metal Matrix Composites with four samples in each category are newlinefabricated. The compositions are; category 1 contains Aluminium and alumina, newlinecategory 2 contains Aluminium and Tungsten Carbide while category 3 has newlineAluminium, Alumina and Tungsten Carbide as hybrid composites. newlineVarious mechanical test namely tensile, compression, hardness and impact are newlineperformed to study the Mechanical behaviour of the Aluminium Composites. newlineMoreover, the hybrid composite having better mechanical properties are subjected to newlinewear analysis and also Wire Electrical Discharge Machining process. Here, the wear newlinebehaviour of Aluminium-Alumina-Tungsten Carbide hybrid metal matrix composite is newlineanalyzed. 9 experiments are designed according to L9 Taguchi orthogonal array. The newlineminimum specific wear rate is to be calculated for optimal combination of load newlineapplied, sliding speed and sliding distance in wear testing machine. Wire Electrical newlineDischarge Machining is also performed to determine the optimal machining parameters newlineof hybrid composite which has best mechanical property. The larger material removal newlinerate and the smaller surface roughness are analysed as responses for the four input newlineprocess parameters namely, Current, Wire Traverse Speed, Pulse On Time and Pulse newlineOff Time which are optimized using L16 Taguchi orthogonal array. newlinev newlineIt was found from the tensile test that if the content of Alumina increases, newlinethe Tensile Strength increases proportionally. In fact, as the Alumina content is newlineincreased from 1% to 4%, the tensile strength (TS) increases by about 50%. Moreover, newlineas the Alumina content is increased from 1% to 4% the ductility increases from 3.7% newlineto 5.57%. The result of compression test shows that as the Alumina content increased newlinefrom 1% to 4%, the compressive strength decreases by about 24%. This is due to the newlinealumina particles not acting as barriers to dislocations in the microstructure and the newlinedispersion-strengthening effect is expected to be retained even at elevated temperatures newlineand for extended time periods because the particles are unreactive with the matrix newlinephase. The result of impact test shows that as the % reinforcement increases, the newlineimpact energy decreases. Increase in the hardness of the material makes it brittle which newlinemakes the material breaks at a lesser energy. It is also observed that impact strength newlineobtained by Charpy test is same till 2% WC and then decreases with further increase newlinein tungsten carbide particles. The result of hardness shows that as the Alumina and newlineTungsten Carbide content increases, the hardness of the composite material decreases newlinemonotonically by significant amounts. In fact, as the Alumina content is increased newlinefrom 1% to 4% the hardness increases by about 15%. newlineThe wear behaviour of Aluminium-Alumina-Tungsten Carbide hybrid metal newlinematrix composite analyzed using 9 experiments shows that as the applied load newlineincreases, the wear rate also increases. The amount of sliding wear is proportional to newlinethe applied load and the sliding distance and inversely proportional to the hardness of newlinethe surface being worn away. It is evident from the results that the sliding speed is an newlinein significant factor which contributed to the wear rate of the hybrid composite. But, it newlineinfluences the wear with the combination of applied load and sliding distance, where newlinethe frictional heat generated between pin and the steel disc is influenced. newlineThe result of Wire Electrical Discharge Machining performed using L16 newlineTaguchi orthogonal array shows that the addition of higher reinforcement particles to newlinethe matrix alloy possess higher strength and hardness to its structure, hence material newlineremoval is less when compared with low addition of reinforcement particles. newline