Investigation of a Pulsed DC Arc Spray Process

Abstract

Abstract The modulated direct current of pulsed arcs can be used to influence heat input and drop size in a process reliable and reproducible manner. Modern power sources possess arc controls due to the development in the area of computer engineering, which enable thermal spraying with pulsed current due to their dynamics and efficiency. In order to use this technology in the area of arc spraying (AS), investigations are required on the process behavior depending on the electrical parameters. A plant prototype was available for this investigation. The experiments were conducted using a wire-shaped spraying consumable of an iron-base alloy with a diameter of 1.6 mm. Parameters relevant for the process such as background current Iground, pulsed current Ipulse, pulse duration tpulse etc. were varied and measured using appropriate measuring technology. The objective was to develop an understanding of the process and to determine suitable parameters. Using high speed imaging, the arc was monitored and the melting of the consumables was analyzed. The influence of the pulsed current on the coating was determined by evaluating the porosity and the oxidic phase fractions by using a light microscope. Furthermore, the particle sizes were determined. Layers generated with conventional processes served as a comparison. The investigations on pulsed AS were able to prove stable process characteristics and improved coating results compared to conventional AS.