Multi-pass sub-critical load testing of titanium nitride coatings

TiN coatings deposited by closed field unbalanced magnetron sputter ion plating (CFUBMS) have been scratch tested in two modes. An initial conventional scratch test has been carried out to determine the critical load, and multiple scratches have been made over single tracks at different fractions of the critical load. It is shown that, even at very high fractions of the critical load, the coatings do not fail adhesively or cohesively; rather, they simply become progressively thinner with successive passes of the diamond. Scanning electron microscopy of the worn surfaces has revealed a previously unobserved wear mechanism that shows that the coating adhesion can be truly described as perfect. (C) 2000 Elsevier Science B.V. All rights reserved.