Professor Allan Matthews, Professor of Surface Engineering and Tribology at The University of Manchester and the Director of the BP International Centre for Advanced Materials, delivered the fourth ICAM webinar of 2017 on the topic of developing and selecting tribological coatings.
For many years, it was widely believed that the best way to reduce the wear of a surface was to make it harder. This idea was implicit in one of the guiding ‘laws’ of wear (Archard’s Wear law) which stated that wear rate is directly proportional to load and inversely proportional to hardness. In practice, this ‘law’ doesn’t hold true, at least not in the vast majority of real-life wear situations, but this “myth” is still perpetuated in many tribology textbooks.
In practice, what we do know is that both the elastic modulus (E) and the hardness (H) must be considered together when seeking to reduce wear. In fact it is the ratio H/E which gives us the best indicator of wear resistance, especially for coatings.
In this webinar, the reasons for this were discussed and the implications for the development of improved wear-resistant surfaces are outlined, with examples of surfaces which take the optimisation of the H/E ratio as the goal.
Examples of coatings which achieve this were also discussed, including nanocomposite and nanolayered coatings. Mention was also given to so-called ‘duplex’ coating systems, which combine surface treatments with coatings to gain maximum tribological benefits.
Professor Allan Matthews is Professor of Surface Engineering and Tribology in the Department of Materials at The University of Manchester and Director of the BP International Centre for Advanced Materials. He is a Fellow of the Royal Academy of Engineering.
Professor Allan Matthews has published over 300 refereed papers as well as several books and book chapters. He has had a central role in many professional and learned societies, including the British Vacuum Council, the American Vacuum Society and the Society of Vacuum Coaters. Professor Allan Matthews has received several awards, including the IoM3 Gold Medal in 2011. He is Editor-in-Chief of the Elsevier journal Surface and Coatings Technology.