Publication

Abstract : One of the objectives of this research work is to fabricate the AA 7075 - Silicon Carbide (SiC) and Graphite (Gr) hybrid Metal Matrix Composite (MMC) containing 5 wt% of SiC and 2 and 4 wt% of graphite using the stir-casting technique. The other objective of this study is to know the effect of reinforcements on mechanical and dynamic characteristics of 7075 hybrid Composite. The 7075-SiC-Gr MMC is characterized by Scanning electron microscope (SEM), Energy dispersive X-ray (EDS) spectroscopy and X-ray diffraction (XRD) analysis. Microhardness tests are conducted on both the varieties of MMC and found that the microhardness was improved considerably in the case of 2% of Graphite when compared to 4% of Graphite with respect to the base metal. Dry sliding wear tests were conducted using Pin-on-Disc machine as per ASTM G99-95A standard. The results reveal that the wear resistance of 7075 hybrid MMC is improved considerably with respect to the base metal. Dynamic characteristics such as natural frequency and damping ratio of both composites and unreinforced AA 7075 are evaluated at room temperature. Damping ratio and natural frequency corresponding to the fundamental mode of vibration are found using an impulse hammer test. The results reveal that reinforcing AA 7075 matrix with SiC and graphite particles improves mechanical and dynamic characteristics. The 2 wt% of graphite composite exhibits better dynamic characteristics than that of the 4 wt% of graphite composite and aluminium alloy 7075.