A wear-resistant coating is a coating made using wear-resistant substances. This means they wear easily when rubbed against highly abrasive materials without damaging the underlying material.
The primary function of wear-resistant coatings is to enable automatic gap adjustments to account for thermal fluctuations and other physical events that exist over the operational life of a particular piece of equipment. This type of coating is widely used in environments involving turbojet machinery. The clearance between the housing and the turbofan or fan blade tips should account for concentricity differences and thermal expansion. To protect against catastrophic tip-to-case contact, larger clearances should be promoted.
Since the 1990s, air traffic has increased significantly while total fuel consumption has remained constant. Jet engine manufacturers offer solutions by increasing power generation and engine efficiency. Increased operating temperatures make this possible thanks to lightweight materials and improved aerodynamics. A more effective and better solution is to reduce the gap between the case and the turbofan. With wear-resistant coatings, this can be achieved by increasing the surge margin, thereby increasing the safety and stability of engine flow.
However, wear resistant coatings are not limited to aero engines. They can be applied to almost any type of rotating equipment, such as:
radial compressor
gas turbine
Pump
Turbocharger
In aerospace engine applications, abradable coatings work by reducing the gap between the fan blade tip and the casing. This causes the turbofan to rub next to the shroud. This phenomenon can be highly tolerated by covering the shield with an abrasion-resistant coating. These coatings release all types of fine wear dirt and debris without causing blade wear.
The improvement of wear-resistant coatings requires a variety of tests, from powder fabrication to selection of maximum thermal spray procedures. All of these are designed to simulate field trials and laboratory tests. This has led to the identification of wear-resistant coatings by engine manufacturers. The goal is to create a protective seal that won't cause blade wear. Ideally, the wear-resistant material should be able to maintain a smooth shield facade and remain intact for many years.
