Micro-scale impact testing - a new approach to studying fatigue resistance in hard carbon coatings

Beake, BD, Liskiewicz, TW ORCID: https://orcid.org/0000-0002-0866-814X, Bird, A and Shi, X (2020) Micro-scale impact testing - a new approach to studying fatigue resistance in hard carbon coatings. Tribology International, 149. p. 105732. ISSN 0301-679X

Preview

Accepted Version Available under License Creative Commons Attribution Non-commercial No Derivatives. Download (2MB) | Preview

Abstract

© 2019 Elsevier Ltd Improving the fatigue resistance of DLC coatings under highly loaded repetitive contact is an important step to increasing their performance in demanding applications. The nano-impact test has been shown to be effective at highlighting differences in resistance to contact damage in thin hard carbon coatings deposited on hardened steel. A novel micro-scale rapid impact test capability capable of producing repetitive impacts at significantly higher strain rate and energy than in the nano-impact test has been developed recently enabling the study of coating fatigue with less sharp spherical indenters than in the nano-impact test. Results with the new micro-impact technique on two commercial hard carbon coatings (Graphit-iC and Dymon-iC from Teer Coatings) on tool steel are presented. The role of coating mechanical properties on the fatigue resistance and the load-sensitivity of the impact failure mechanism is discussed. The harder coating with higher sp 3 /sp 2 bonded C (Dymon-iC) was found to be significantly less durable under fatigue loading than the softer Graphit-iC. Reasons for the observed differences are discussed.