How carbon black nanoparticles affect the occurrence of soft-sparking during plasma electrolytic oxidation

Abstract

The effect of dispersed carbon black nanoparticles in the electrolyte on the plasma electrolytic oxidation of aluminium under soft sparking regime is investigated. Increasing the concentration of particles reduces the breakdown voltage. It also makes the transition to soft sparking to occur earlier, which can favour a more homogeneous coating. However, it is shown that a too high concentration of particles can be detrimental to the coating morphology despite an apparent soft sparking regime characterized by a decrease in anodic voltage.