Microstructural evolution and sliding wear studies of copper-alumina micro- and nano-composites fabricated by spark plasma sintering

Abstract

Copper-alumina nanocomposites of 0.5, 1, 3, 5, 7 vol.% alumina (average size <50 nm) reinforced in copper matrix were fabricated using spark plasma sintering (SPS) technique. Another set of microcomposites containing 1, 5, 20 vol.% of alumina (average size ∼10 μm) had been fabricated to compare the physical as well as mechanical attributes of composites with variation of reinforcement particle size. These micro- and nano-composites have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) followed by microhardness, nanoindentation hardness, and wear measurements. It has been found that hardness values are higher for nanocomposites as compared to microcomposites. It is also found that wear resistance increases with increasing alumina content. The microcomposites show better wear resistance than nanocomposites for the same composition. The interaction of copper and alumina results in the formation of CuAlO2 which manifests differential interfacial phenomenon. We have obtained 95.82% densification and 93.17 HV hardness for spark plasma sintered Cu-20 vol.% Al2O3 microcomposite. The wear rate is appreciably low, that is, 0.86×10-4 mm3N-1m-1 for 20 vol.% alumina reinforced copper microcomposite.

Keywords

• cu-al2o3
• microcomposite
• nanocomposite
• nanoindentation
• spark plasma sintering