• Hausberger, Andreas
• Cerne, B.
• Slapnik, J.
• Stiller, Tanja
• Manning, N.
• Jarry, O.
• Grün, Florian
• Tervakangas, S.

Abstract

In industrial applications, metal parts are often coated to prevent wear and thus extend their service<br/>life. In some cases, metal parts are replaced with polymers for weight reduction and lower energy<br/>consumption during manufacturing. One drawback is that polymers are softer than metals and hence<br/>more susceptible to wear. A more recent approach is to coat the soft polymer with a hard, wearresistant<br/>coating. The best-known coatings for this are diamond-like carbon coatings and their subset,<br/>amorphous carbon coatings. The coating process is challenging considering the temperature limits and<br/>the correlation between coating thickness and bonding.<br/>In this study, a-C and ta-C coatings were deposited on polymers and tested under 3 different contact<br/>conditions, i.e. ball-on-disc, pin-on-disc, and 2-disc-test. This represents a transition from model to<br/>component testing. Indentation tests were performed to understand the interaction between polymer<br/>and coating. Depending on the coating, the behaviour was either elastic or plastic, which helped to<br/>understand the stress distribution in the contact.<br/>Hertzian contact pressure with a steel ball causes wear on the mating part and the coating. By replacing<br/>the mating part with a polymer, only the polymer mating part will wear. Changing the tribosystem to a<br/>flat contact showed a significant reduction in wear. One reason for this is the increased contact area,<br/>which leads to a changed stress distribution. With the change from flat to line contact and a change in<br/>movement (from pure sliding to sliding-rolling), the shear forces between the coating and substrate are<br/>significantly reduced. The effect of speed, load, and slip ratio on the performance of the different<br/>material pairings was analysed. Coated polymers also allow the pairing of incompatible materials, which<br/>would result in unstable frictional contact. Moreover, coated polymers exhibit high wear resistance as<br/>long as the load is applied over an area rather than a small point.

Topics

• impedance spectroscopy
• polymer
• amorphous
• Carbon
• wear resistance
• steel