Friction and wear properties of AZ91 alloy reinforced by CNTs coated with MgO

AZ91 alloy reinforced by carbon nanotubes coated with MgO（AZ91-MgO@CNTs） was prepared by powder metallurgy, hot extrusion and T4 treatment. The influences of MgO@CNTs content and load on the friction and wear property, surface wear morphology and debris topography of AZ91-MgO@CNTs composites were investigated under the dry sliding friction. The results show that MgO@CNTs can improve the wear properties of AZ91-MgO@CNTs. With increasing the content of MgO@CNTs, the strengthening effect of the wear properties of the composite increases and then decreases. Compared with AZ91-CNTs, AZ91-MgO@CNTs has smaller friction coefficient and lower abrasion loss, indicating that the MgO@CNTs is better than CNTs to improve the wear properties of AZ91 alloy. The main wear mechanism of AZ91-MgO@CNTs is abrasive wear under the load of 10 N. When the load is 50 N, there are three wear mechanisms appeared: abrasive wear, oxidation wear and adhesive wear.