DEVELOPMENT OF THERMAL STABLE STIR CAST FIBER CEMENT PARTICLES- ALUMINIUM METAL MATRIX COMPOSITE

Abstract

There is an increasing need for high heat bearing lightweight materials in the aerospace, automotive and thermal management industries. In this research, an attempt was made towards developing a composite material based on the lightweight of aluminium and the high thermal tolerance of fiber cement particles (FCP). The intended area of application of this composite is in the combustion engine of a solid rocket motor. The fiber cement particle was obtained by pulverizing fiber cement sheet. Gradation test was carried out on the FCP in order to obtain a particle size of 40 microns. The FCP was introduced into a melt of aluminium AA7104 via stir cast technique. The addition of FCP was varied at 10%, 20%, 30%, 40% and 50%. Particles sizes below 40 microns led to coagulation of the particles and uneven particle distribution. The developed composite was characterized in order to generate data on its mechanical properties. The mechanical properties data obtained were used to simulate the combustion chamber of a sounding rocket enginein ANSYS steady state thermal analysis, based on the fuel formulation of potassium perchlorate (67%) and sorbitol (33%). The expected chamber temperature of the fuel-oxidizer mixture was projected to be 2420.573𝑜𝐶 using Propep fuel characterization. It was observed that the thermal stability of the composite increased with increasing addition of the FCP. The control sample was thermally stable up to 650.3𝑜𝐶, the 10% reinforced composite was thermally stable up to 1001.1𝑜𝐶, the 20% reinforced composite was thermally stable up to 1502.2𝑜𝐶, the 30% reinforced composite was thermally stable up to 1802.8𝑜𝐶, the 40% reinforce composite was thermally stable up to 2203.7𝑜𝐶, and the 50% reinforced composite was thermally stable up to 2604.6𝑜𝐶. Although the thermal stability of the composites increased with increasing addition of FCP, however best thermal stability was observed in the 50% reinforcement amongst the samples analyzed. This improvement in thermal stability can be attributed to the formation of a third phase in the microstructure of the composites and this third phase was found to be intermetallic in na