Cathodic-arc deposition with boron-alloyed titanium cathodes

Titanium cathodes containing low boron concentrations were recently found t o be important for (1) the reduction of droplet emission and (2) the format ion of a denser structure of reactively deposited Ti-B-N hard coatings. Bas ed 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 ar e voltage (at constant current), the cathode erosion, the evaporation-relat ed substrate current and the critical are current with increasing boron con tent. The Ti-B-N coatings deposited in a laboratory system were characteris ed in particular for their morphology, hardness and roughness, the latter b eing strongly reduced with increasing boron content. Thermal treatments (65 0 degrees C) showed an increasing thermal stability with increasing boron c ontent. (C) 1999 Elsevier Science S.A. All rights reserved.