The Tribological Behavior of TiN Coatings Prepared by IBAD

Abstract

Ion Beam Assisted Deposition (IBAD) provides the ability to control the micro-structure, and therefore the properties of thin films and coatings. This paper describes the tribological properties of TiN coatings prepared by reactive IBAD using evaporation of Ti from an electron beam evaporator in a 10−3 to 10−4 Pa partial pressure of nitrogen and simultaneous bombardment with a directed beam of 0.5 keV Ar+ ions. Films prepared with an Ar+ to Ti atom arrival rate ratio of 0.1 were found to be soft (Knoop hardness of < 1000 with 5 gr load) while those prepared at an arrival rate ratio of 0.4 were hard (Knoop hardness of ~2000 at 5 gr load). Transmission electron microscopy of the films showed the soft films had significant porosity at the grain boundaries while the hard films had almost none. All films were highly adherent. The wear life during pin on disk testing was a complex function of film hardness, ductility and debris formation.