Effect of sintering on mechanical property of SiC/B4C reinforced aluminum

Abstract

In this study, SiC (silicon carbide) and B4C (boron carbide) added Al 7075 based composites were prepared at 40%, 20% and 10% reinforcement ratios. Using powder metallurgy, composite sample with 9 different structures were produced at 700 MPa pressing pressure, at 550 °C in 90, 120, 150 min applying three different sintering times. According to Archimedes principle, theoretical densities of composite samples were calculated. Then, the hardness measurements and transverse rupture tests were conducted. Lastly, wear tests were conducted using the Pin on Disc Method. Images of composite samples were taken at optical microscope and Scanning Electron Microscope (SEM), and the microstructures were examined. It was determined that increase in SiC and B4C reinforcement ratios decreased the fracture resistance. However, when every reinforcement ratio was evaluated separately, it was observed that increase in sintering time affected the fracture resistance positively. Increase in sintering time also increased the density values, and the hardening values and wear resistance decreased. Increase in reinforcement ratios and sintering time affected the composite wear behavior negatively. Increase in reinforcement ratio in composite structure decreased the density; however, hardening values increased. In conclusion, in such type of composites, reinforcement ratios in definite proportions (∼20%) affect mechanical features positively, and excess in that ratio affect mechanical features negatively. Especially 40% reinforcement ratio was high for such type of composites and was not suitable for mechanical features.