Investigations Of A Pulsed DC Arc Spray Process

Modern machines for arc spraying enable to control the melting-off behavior of the electrodes and influence thus the layer quality positively by modulation of the arc current. This paper is a contribution for an investigation of a pulsed DC-process in which electrical parameters such as pulse frequency f, pulse voltage U_P, basic current I_grd, pulse time t_P, control speed V_Dyn, and the static slope of the characteristic curve in the pulse phase n_P are varied. By means of the respective current and voltage profiles the influence of the electrical parameters to the process performance and stability as well as process limits are shown. The melting-off behavior of the electrodes in the DC pulse process is analyzed by means of high-speed recording. The movement of the modulated electric arc in the process, the particle detachment and distribution and the process parameters are compared to a conventional arc spraying process. Finally, selected samples are evaluated metallographically to determine the influence of the pulse parameters on the layer quality.