Study of Corrosion and Tribological Properties of Microwave-Sintered NiCu-Al2O3 Nanocomposites

The work evaluates the effect of Al2O3 nanopowder addition on microstructure, tribological and corrosion properties of CuNi-Al2O3 nanocomposites. The elemental powders of Cu and Ni contains 0, 10 and 20 vol. % of Al2O3 nanopowder were mixed in a high-energy ball mill in Ar atmosphere for 30 h. Phase transformation of the alloyed powders obtained were characterized by X-ray diffraction (XRD). The results show that CuNi solid solution alloy was formed during mechanical alloying (MA) process through milling-induced interdiffusion of the elements. Mechanically alloyed powders compacted under cold pressure at 350 MPa. The green compacts were sintered in microwave furnaces (2.45 GHz) for 90 min at 600 W radiation powers. The microstructural analysis of the cross section of the sintered samples was made using scanning electron microscopy (SEM). The sintered sample show fully dense microstructure without any radial cracks. Tribological properties of sintered nanocomposites were evaluated by ball-on-disk wear test. Increasing the Al2O3 content in the nanocomposite decreased the wear rate and coefficient of friction. These results showed that the addition of Al2O3 nanopowder in the NiCu matrix caused improves its wear behavior. The corrosion performances of nanocomposites were evaluated by potentiodynamic polarization in 1 M NaOH solution. Corrosion experiments show that addition of Al2O3 nanopowder is not effective on the corrosion behavior.