Modification of different areas of copper surface by diffuse discharges at atmospheric pressure

Pulsed power can be used for the generation of low-temperature plasma, and different discharge modes, which has been widely used in the field of surface modification¹, ². In this paper, modification on the copper surface by nanosecond-pulse diffuse discharges with a tube-to-plane gap is conducted in atmospheric air. The characteristics of the diffuse discharges are investigated to determine the modification conditions. The experimental results show that there are three typical regions in the diffuse discharges, i.e. central region, diffuse region and the edge region. Different regions play different roles in the surface modification. It is found that diffuse region has the best performance in the treatment. Furthermore, the hydrophilic property and surface energy are significantly enhanced after the modification. Compared with the untreated sample, both the nitrogen and oxygen proportions for the diffuse region and the edge region significantly increase, but the corresponding carbon proportion decreases. However, nitrogen and oxygen proportion for the central region slightly changes after the modification, but the corresponding carbon proportion increases. In addition, Micro-hardness measurements show that the surface hardness increases about 25% after the treatment.