Arc spraying with dynamic current generators

Low running costs, high spray rates and efficiency make electric arc spraying a good tool for coating large areas with high production rates. The main applications are in the field of corrosion and wear protection of large structures, e. g. parts for bridges or offshore industry. New applications are expected for high quality coatings produced by cored wires. Disadvantages of the arc spraying process are that only electrically conductive wires can be processed and the lower particle velocity in comparison to other thermal spray processes like HVOF or APS. Depending on the process parameters the oxidation of particles has a negative effect on the mechanical and the electrochemical properties of the coating, too. In this paper some investigations with new and flexible power supply systems for arc spraying are presented. The particle size and the morphology of the coating can be optimised, due to the possibility of changing the current generator characteristic and modulating the power by pulsing up to 500 Hz. The oxidation of particles can be reduced by a lower heat input based on lower spray voltage. For a higher quality of the coating microstructure investigations with dynamic generators were performed for Zn, Al, ZnAl, 110MnCrTi8 and Al. An enhancement of the process stability was achieved, too.