Dry tribological behavior of Mg/SiCp composites at room and elevated temperatures

• Mg--15% SiC showed superior wear resistance at all test temperatures.
• A transition load from mild to severe wear was identified for the samples.
• At the wear temperature of 25 °C the transition load was 20 N for the specimens.
• At higher temperatures the transition load increased with increasing SiC content.
• Mild wear of the composites was due to formation of tribolayer on the wear surface.

Pure magnesium and its composites reinforced with 5, 10 and 15 vol% SiC particulates with a mean diameter of 7.8 µm were fabricated by a powder metallurgy process. The tribological behavior of the samples was investigated under normal loads of 5–60 N at sliding speed of 0.4 m/s and at wear temperatures of 25–200 °C. At the wear temperature of 25 °C, results showed almost close wear rates under normal loads of 5 and 20 N. However, under higher normal loads the composites showed lower wear rate than that of the unreinforced magnesium. At the higher wear temperatures of 100, 150 and 200 °C, a significant lower wear rate was observed for the composites compared to the pure magnesium. Increasing the normal load resulted in a transition from mild to severe wear at all wear temperatures. Below the transition load oxidation was a dominant wear mechanism, while above that severe plastic deformation and adhesion were the main wear mechanisms. The results also showed wear rate improvement of the composites with increasing SiC content. Finally, a wear map showing mild and severe wear regimes as a function of load and wear temperature was adopted for the composites.