Microstructure, Mechanical and Wear Behavior of Hybrid Rice Straw Ash/Silicon Carbide Reinforced Al-Zn Composites Fabricated via Double Stir Casting

Abstract

Aluminum is mostly adopted as a structural material in the automotive and aerospace industry due to its light weight and amenability to different processing techniques. Nevertheless, low melting point and inadequate strength are some of the challenges faced by this material. The addition of reinforcement elements such as silicon carbide and alumina particles has been used as an affordable method of solving this problem. However, finding a cost effective and environmentally friendly reinforcement materials has led to the use of agricultural waste. There is little or no literature on the use of rice straw ash as a reinforcement for Al-Zn alloy, Hence, this research work investigated the microstructure, mechanical and wear properties of hybrid Rice Straw Ash/Silicon Carbide particulate reinforced Al-Zn Alloy at varied weight percent of 10% each fabricated via double stir casting technique. Hardness, ultimate tensile strength, impact strength and wear properties of the fabricated composites were investigated. Scanning Electron Microscopy (SEM-EDS) analysis was carried out on as - cast aluminum alloy and composites to assess the structures of developed composites. The SEM result of the unreinforced aluminum alloy shows a single phase with zinc dendrites, while that of the hybrid rice straw ash/silicon carbide composites reveals the dispersion of reinforcements within the aluminum matrix, and the EDS shows high peaks of aluminum (Al), oxygen (O), carbon (C), Magnesium (Mg) and silicon (Si). The hardness values and ultimate tensile strength of the hybrid reinforced composites increased with increasing percentage weight of the rice straw ash addition. The increase hardness and strength might be due to the presence of hard ceramic phases in the matrix. The As - cast aluminum alloy has the best impact strength, while the impact strength values decrease as the percentage weight addition of the hybrid composites increases. The wear resistance improves as the weight percent of rice straw ash increases. This work has demonstrated the viability of Rice Straw Ash/Silicon Carbide reinforced AMCs for different structural applications as its mechanical and wear properties exceed that of the Al-Zn alloy, hence contributing to the nation’s economy by turning the rice straw wastes into a valuable composite material.