When we think of a surface wearing we tend to imagine material being eroded away, perhaps by corrosion, abrasion, or chemical wear. But "wear" actually describes many dozens of mechanisms that change a surface, including many that add or redistribute material. Some wear is good (running in a new engine, for example), other wear is bad (pits and cracking that may lead to part failure), and some does not affect performance at all. Is the worn surface stable? How long before failure? Theses are some of the critical questions we ask when looking at a surface as it wears.

In this lecture we discuss the nature and mechanisms of wear and how they progressively modify a surface and alter its functionality. We introduce methods for measuring wear, including accelerated wear testing. Thirdly, we delve into the many surface texture parameters that can be used to quantify wear, and to control it in production and over a component's lifetime. And lastly, we look at the relationships between wear and material properties such as elastic/plastic deformation, stress/strain, surface energy, etc.

Dr. Donald Cohen draws on many real-world stories and case studies from his 30+ years in surface and wear analysis to illustrate the importance of wear measurement and control.

This module is Part 4 of the 10-part Surface Texture and Tribology short course. The full course is available on udemy, or you can select the individual course modules of interest to you. Enter "surface roughness texture tribology" in the udemy search bar to browse the full course and modules.