DLC-Coated Thermoplastics: Tribological Analyses Under Dry and Lubricated Sliding Conditions

Abstract

The purpose of this study was to increase the limited wear resistance of polymers in highly stressed tribological contacts. Therefore, diamond-like carbon (DLC) coatings were firstly developed and deposited on polymers. The development of the low temperature coating process was conducted on an industrial scale coating unit. Due to the use of polyether ether ether ketone (PEEK) and polyamide as substrate material, the coatings were tailored in accordance with different mechanical properties of the polymers. Furthermore, analyses regarding morphology, roughness as well as compound adhesion between coatings and polymers were conducted. The tribological analyses were accomplished for reciprocating sliding kinematics on pin-on-plate tribometer under dry conditions as well as boundary lubricated conditions. The results prove the ability of the coatings to undergo high plastic deformations without delamination. In addition, the possible formation of a composite layer of DLC and PEEK in the wear track due to high energy input under dry conditions was shown. Furthermore, the transformations of sp2 chain into ring bindings as well as a change of size and distribution of the sp2 clusters during dry contact conditions were observed.