Cathodic-arc deposition with boron-alloyed titanium cathodes

Titanium cathodes containing low boron concentrations were recently found to be important for (1) the reduction of droplet emission and (2) the formation of a denser structure of reactively deposited Ti-B-N hard coatings. Based on these results, detailed studies on the cathode behaviour and the Ti-B-N coating properties were performed using titanium cathodes containing 0-7.5 at% boron and cemented carbides and alpha-iron substrates. The cathode characteristics showed a more or less marked decrease of the are voltage (at constant current), the cathode erosion, the evaporation-related substrate current and the critical are current with increasing boron content. The Ti-B-N coatings deposited in a laboratory system were characterised in particular for their morphology, hardness and roughness, the latter being strongly reduced with increasing boron content. Thermal treatments (650 degrees C) showed an increasing thermal stability with increasing boron content. (C) 1999 Elsevier Science S.A. All rights reserved.