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AA5052/ZrB2 particulate aluminum matrix composites (PAMCs) have been produced by in situ reaction of K2ZrF6 and KBF4 compounds with molten alloy at about 860 °C. Dry sliding wear and friction of composites have been investigated for a particular sliding velocity and sliding distance at different loads from ambient temperature to 200 °C. It is revealed that for a particular load and temperature, wear rate and normalized wear rate decrease with increase in the volume percentage of ZrB2 particles whereas coefficient of friction (COF) shows a reverse trend. Wear rate and COF also increase with increase in temperature for a constant load and composition. Whereas with load for a particular temperature, wear rate and wear rate per unit vol. % ZrB2 increase while COF decreases. Worn suiface and wear debris morphology examined under scanning electron microscopy (SEM) and profilometer to understand the wear mechanism revealed that wear mode transition takes place from mildoxidative to severe-metallic at 100°C for unreinforced alloy, whereas a shifting is observed in transition temperature from 100 to 150°C for composite with 9 vol. % ZrB2 particles. Energy dispersive spectroscopy (EDS) analysis of worn suiface confirms the oxidative wear mode. Profilometry results indicate that wear surface has higher suiface roughness at higher values of load and temperatures. Prior to wear and friction studies, composites were also characterized by X-ray diffraction (XRD) and SEM for morphology and microstructural characteristics to correlate with wear results. The findings are very helpful to make the AA5052IZrB2 composites suitable for the applications, where high-temperature wear is a limiting factor. [ABSTRACT FROM AUTHOR]

Particulate aluminum matrix composites (PAMCs) with different volume percent of 3Zr particles have been developed by direct melt reaction (DMR). Wear and friction have been studied in detail for all compositions under dry sliding conditions. Results indicate that the wear rate, normalized wear rate, and wear coefficient of PAMCs decrease continuously with increase in volume percent of 3Zr particles, however, with applied load and sliding distance, wear continuously increases. Wear rate and wear coefficient with sliding velocity initially decrease for all compositions, attains minima, and then increase sharply. However, coefficient of friction shows increasing trend with composition and sliding velocity but with load it shows a decreasing trend and with distance slid it fluctuates within a value of ±0.025. At low load and sliding velocity three-dimensional (3D)- profilometer, scanning electron microscope (SEM), and debris studies show low Ra values and mild wear dominated by oxidative nature, whereas at high loads and sliding velocities high Ra values and wear nature change to severe wear with mixed mode (oxidative- metallic) and surface with deep grooves is observed. Further, it is also important to note from morphological studies that refinement of matrix phase takes place with in situ formation of 3Zr particles, which helps to improve hardness and tensile properties finally contributing to low wear rate. [ABSTRACT FROM AUTHOR]