Influence of rutile (TiO2) content on wear and microhardness characteristics of aluminium-based hybrid composites synthesized by powder metallurgy

The effect of rutile (TiO2) content on the wear and microhardness properties of aluminium (Al)-based hybrid composites was explored. The proposed content of TiO2 (0, 4%, 8%, 12%, mass fraction) was blended to Al-15%SiC composites through powder metallurgy (P/M) process. Wear test was conducted using pin-on-disc apparatus under dry sliding conditions. Fabricated preforms were characterized using X-ray diffractometer (XRD), scanning electron microscope (SEM) and energy-dispersive X-ray spectrometer (EDS). Optical micrographs of the composite preforms display uniform distribution of TiO2 throughout the matrix. Quantitative results indicate that wear resistance and microhardness increase with the increase of TiO2 content. SEM images unveil that high wear resistance is attributed to high dislocation density of deformed planes and high hardness of TiO2. SEM images of wear debris display gradual reduction in mean size of debris when TiO2 content increases. EDS spectra confirm the presence of oxide layer which obviously reduces the effective area of contact between the sliding surfaces thereby lowers the wear loss of composites. The observation concludes that delamination and adhesive wear are the predominant mechanisms.