Fracture initiation mechanisms of thin hard coatings during the impact test

摘要: The impact test can be successfully applied for the characterization of thin and thick coatings fatigue creep properties, respectively. In present paper experimental analytical investigations concerning films fracture initiation during this are introduced. damage hard deposited on smooth surfaces is mainly induced by mechanisms characterized removal film segments in contact area between ball indenter specimen highly superficially loaded regions test. Herein currently used coating stress determination methodologies, when applied, lead most cases to sufficiently accurate results. Superficial PVD layers a basic do not affect occurring field practically thus no differences encountered. When surface roughness increases, localized concentrations throughout occur, resulting failures randomly distributed spots, at predictable high loads. relatively soft or elevated substrate roughness, abrasive wear contribution has considered. such cases, as will explained, first appears region, close middle radius.