Experimental study of wear-induced delamination for DLC coated automotive components

The trends in automotive industry are towards higher performance, improved reliability, reduced tolerances and more environmental friendly products. Wear resistance enhanced mechanical components exhibiting lower friction help achieving this major challenge. Diamond-Like Carbon (DLC) deposited on mechanical components operating under lubricated conditions at temperatures between 100 and 250 degrees C, efficiently decrease the friction coefficient and insure wear protection. Wear induced debonding and blistering of hard surface coatings is still a major problem in the automotive industry. There are several open questions. Where does debonding start? Where does the interface crack propagate? Where does it deviate leading to delamination? In this work, we show how the combination of the latest experimental techniques allows to answer these questions and thus better control wear. Blistering is influenced by the overall stress in the coating and the very local microstructure of the substrate. A combination of AFM and nano-indentation measurements, as well as FIB milling with in situ FEG-SEM observations and local chemical measurements by EDX, allows to observe closely and better understand wear-induced delamination. The new availability of such physical and chemical investigations should improve mechanical and physical-based models to predict wear and enhance coating adhesion.