No abstract

No abstract

The emission of microdroplets from the cathode surface in the vacuum arc ion plating deposition technique is the major drawback to the technique’s industrial use. The generation of these particles from graphite cathodes is studied in this article and correlated to the local thermal load in the cathode spot area. A pulse discharge was used for a precise control of this load. Increases in the arc current level, arc duration time, and, more generally, the local temperature of the cathode were found to increase the number and the average size of the emitted particles. Particles under these conditions also show an increase in the width of their size distributions. Increasing the distance between cathode and substrate was found to decrease the number density of particles observed on the substrate according to the solid angle covered. The microdroplets show a graphite structure and diameters between 0.2 and 2.0 μm. Conditions needed to decrease the number of particles emitted to the substrate are given.

Vacuum arc spot movement on various graphite cathode materials is investigated. The dependence of the arc spot velocity on physical, mechanical and electrical properties of the different cathode materials is measured in the presence of a variable magnetic field. It is shown that the cathode spot velocity is larger on cathodes having large grain size, low electrical resistivity and higher apparent density. The spot velocity is lower for cathodes having larger pore sizes and total porosity.

No abstract