In situ real time observation of tribological behaviour of coatings

The functional performance of coatings can be transformed using coatings to form an engineered surface system where resistance to wear and friction are improved relative to the uncoated substrate. Understanding the failure mechanisms of coatings in tribological contacts is difficult to achieve. This paper shows results from real time in situ measurements of tribological behaviour of coated surfaces. Two different test systems have been used. These are a microtribometer fitted inside an SEM which provides sequences of high resolution images of the deformation processes occurring in coatings, and a ball on disc tribometer fitted with imaging and profilometric systems giving real-time information on the tribological response of coatings. DLC and TiN coatings on tool steel substrates were tested in the experiments reported here. Delamination failure of the DLC coatings was observed with both test system. A new rotating scratch test is also described that can provide real-time in situ information on the response of the coatings to repeated abrasion. The in situ results are supported by post-test surface examination.

Automated summary

This paper presents real-time in situ measurements of the tribological behavior of coated surfaces, aiming to understand the failure mechanisms and improve the wear and friction resistance of coatings. Two different test systems, a microtribometer and a ball on disc tribometer, were used to test DLC and TiN coatings on tool steel substrates. The results showed delamination failure of the DLC coatings in both test systems, and a new rotating scratch test was also introduced.