Movement of luminous group spots on target and size modification of micro-particles during cathodic vacuum arc deposition

Abstract

Modification of micro-particle size during cathodic arc deposition is an important issue for the preparation of hard coatings and nanomaterials. In this work, a coil winding and permanent magnets were applied to adjust the magnetic field of a cathodic arc source. The motion of luminous group spots was investigated through high speed imaging method. The average size of the spots was reduced with the decrease of arc current. When the arc current was higher than 80 A, the size probability distributions of the spots presented as bimodal functions. But it turned into unimodal functions at lower arc currents. By changing the coil current three kinds of spots position distributions were observed, such as centered distribution, intermediate and periphery annulus distributions. Their corresponding spots movements were stochastic, spiral and circular motion dominated. The influence of magnetic field on the spots motion was discussed. Although the average spots size was reduced with the increase of coil current to 2.5 A. Further increasing the coil current leaded to a gathering of spots towards the periphery region of the cathode surface, and an increase of the spots size. Finally, a relationship between the spots size and micro-particles size was established.