Song Kexing

Morphology and Frictional Characteristics Under Electrical Currents of Al2O3/Cu Composites Prepared by Internal Oxidation

Two Al2O3/Cu composites containing 0.24 wt.% Al2O3 and 0.60 wt.% Al2O3 separately are prepared by internal oxidation. Effects of sliding speed and pressure on the frictional characteristics of the composites and copper against brass are investigated and compared. The changes in morphology of the sliding surface and subsurface are examined with scanning electron microscope (SEM) and energy dispersive X-ray spectrum (EDS). The results show that the wear resistance of the Al2O3/Cu composites is superior to that of copper under the same conditions. Under a given electrical current, the wear rate of A12O3/Cu composites decreases as the A12O3-content increases. However, the wear rates of the A12O3/Cu composites and copper increase as the sliding speed and pressure increase under dry sliding condition. The main wear mechanisms for Al2O3/Cu composites are of abrasion and adhesion; for copper, it is adhesion, although wear by oxidation and electrical erosion can also be observed as the speed and pressure rise.

Kinetics of internal oxidation of Cu−Al alloy plate

The kinetics of internal oxidation of dilute Cu−Al alloys, containing up to 2.214% molar fraction Al, was investigated over the temperature range of 1023 K to 1273 K, and the depth of internal oxidation was measured by microscopies. A modified rate equation was derived to describe the kinetics of internal oxidation of Cu−Al alloy plate. Based on the derived equation, the permeability of oxygen in solid copper was obtained from the internal oxidation measurements. The experimental results show that the depth of the internal oxidation is a parabolic function of time, there is no evidence for preferential diffusion along grain boundaries and an outer layer of pure copper was formed on the external surface of samples.