Understanding DLC system failure influenced by progressed wear

Abstract

Diamond-like carbon (DLC) coatings are among the toughest and most effective measures for preventing wear on critical surfaces. Due to its high wear resistance, the deterioration of the protective coating only occurs upon failure. Understanding the events leading to failure and identifying a mild-abrasive wear process is crucial for sustainable application. We implemented a ‘Wöhler-like’ test matrix on a tribometer with oscillating tribocontact, employing radioactive isotopes for continuous wear measurements. This method allows to analyse the relationship between load and cycling or test time. When combined with friction coefficient changes, it enables the distinction between mild and severe wear, ultimately pinpointing the point of DLC deterioration. This approach was employed to compare different diesel lubricants, and its effectiveness was demonstrated. The relationship between loading condition and remaining DLC thickness illustrates that mild-abrasive wear is the critical factor for DLC lifetime, ultimately leading to coating system failure.