Wear Independent Similarity.

This study presents a new factor that can be used to design materials where desired surface properties must be retained under in-system wear and abrasion. To demonstrate this factor, a synthetic nonwetting coating is presented that retains chemical and geometric performance as material is removed under multiple wear conditions: a coarse vitrified abradant (similar to sanding), a smooth abradant (similar to rubbing), and a mild abradant (a blend of sanding and rubbing). With this approach, such a nonwetting material displays unprecedented mechanical durability while maintaining desired performance under a range of demanding conditions. This performance, herein termed wear independent similarity performance (WISP), is critical because multiple mechanisms and/or modes of wear can be expected to occur in many typical applications, e.g., combinations of abrasion, rubbing, contact fatigue, weathering, particle impact, etc. Furthermore, these multiple wear mechanisms tend to quickly degrade a novel surface's unique performance, and thus many promising surfaces and materials never scale out of research laboratories. Dynamic goniometry and scanning electron microscopy results presented herein provide insight into these underlying mechanisms, which may also be applied to other coatings and materials.