The friction and wear properties of Mg2B2O5 whisker reinforced 6061Al matrix composite fabricated via power ultrasonic-stir casting process were investigated using a ball-on-disk wear-testing machine against a GCr45 steel counterface under dry sliding conditions. The reinforcements include as-received Mg2B2O5 whiskers and Mg2B2O5 whiskers coated with CuO and ZnO. The volume fraction of the composites is 2%. The relationship between the wear rate and the coefficient of friction was discussed. The results indicate that the wear rate of the Mg2B2O5 whiskers coated with ZnO reinforced aluminum matrix composites is the lowest among the materials. As the applied load and sliding speed steadily increase the coefficients of friction and wear rates of the as-received matrix alloy and the fabricated composites decrease. As the applied load and sliding speed increase, the wear mechanisms of the composites shift from a mild to a severe regime.
Reduced graphene oxide (RGO) and copper composites (RGO/Cu) were successfully fabricated based on a molecular-level mixing method (MLM). The composite powders were reduced in H2 at 350, 450, and 550℃ and then consolidated by spark plasma sintering (SPS) in order to evaluate the effect of H2 reduction temperature on the properties of the composites. The results indicate that the strengths of the composite decrease with the increase of H2 reduction temperature, while the electrical conductivity reaches its maximum at 450 ℃ and minimum at 550 ℃. Hot rolling could benefit the electrical conductivity. The yield strength of the RGO/Cu composite reduced to 337 MPa at 350℃. The electrical conductivity of the RGO/Cu composite reduced at 450℃ after hot rolling reaches 60.26% IACS. The properties of the RGO/Cu composites can be designed by adjusting the reduction degree of RGO and by hot rolling.