Implementation of a switched DC arc power supply for the production of hard coatings

In this work the implementation of a power supply, to produce repetitive switched DC arcs in a Plasma Assisted Physical Vapor Deposition (PAPVD) process is carried out. The control and power circuits as well as the requested software for the automatic management of variables such as inter-electrode voltage, number of applied arcs and active–inactive arc time, are presented. ource allows to make variations of the inter-electrode voltage from 0 up to 280 V rms (root mean square), with a maximum current of 300 A. The active arc time (ta) and inactive arc time (ti) values can be modified into the range of milliseconds, this scale is limited in its minimum and maximum value by other experimental conditions as pressure, target material, gas and anode–cathode distance, among others, which affect the arc extinction time too. A very low inactive arc time and a very long active arc time can place the power supply in a continuous arc mode, where a cooling system is necessary, in this way the main feature of the switched DC arc mode disappears. In order to retain a stable operation, the experiment is performed using a minimum ta of 10 ms and a minimum ti of 500 ms. Higher values can be selected in a broad range. position of TiN coatings on 304 stainless steel has been carried out to corroborate the suitable operation of the source. Some X-ray diffraction (XRD) results are presented from coatings grown by using different number of pulses and different ta.