Investigation on mechanical properties and dry sliding wear characterization of stir cast LM13 aluminium alloy-ZrB2-TiC particulate hybrid composites

In this study, the ceramic particles of titanium carbide (TiC) and zirconium diboride (ZrB2) were used as reinforcements in LM13 alloy matrix to fabricate hybrid composites. The composites along with unreinforced aluminium alloy were produced by varying the weight percentage (wt%) of ZrB2 (0, 2.5, 5 and 10) with a constant 5 wt% TiC through liquid metallurgy stir casting technique. Microstructural analysis of cast samples was made using optical microscope. Various mechanical characteristics such as hardness, tensile strength and ductility were evaluated for the composites and unreinforced aluminium alloy to investigate the effect of different wt% of reinforcements in LM13 alloy matrix. Dry sliding wear performance of the pin samples of LM13 alloy and composites was examined using a pin-on-disk tribometer to study the influence of sliding distance and wt% of reinforcements on the responses like weight loss, wear rate and friction coefficient. Fractured surface of tensile test samples and dry sliding worn surface of pin samples were analyzed through field emission scanning electron microscope. From the experimental study, it is observed that the trend of hardness, tensile strength and wear resistance of hybrid composites increases proportionately with increasing ZrB2 wt% in LM13 matrix. The degree of wear in pin samples exhibited an inverse relationship with the sliding distance after a run of 500 m. Cumulative weight loss of the composites depicted an increasing trend with the applied load during wear test. As compared to unreinforced LM13 aluminium alloy, the hardness, ultimate tensile strength and wear resistance of LM13-10ZrB(2) -5TiC hybrid composite increased up to 63%, 49% and 69% respectively. FESEM worn surface analysis results indicated the transition of wear mechanism from mild abrasive wear to severe delamination with increasing load. ZrB2 and TiC particle reinforced hybrid composites offered better mechanical and tribological properties than TiC reinforced composite and LM13 alloy.