Abradable coatings: Design through microstructure based models

Abstract

Improvised sealing methods are required between rotating and stationary parts in aircraft engines to improve the engine performance significantly by improving thermal efficiencies. To achieve this, use of abradable coatings/seals are proposed. With an abradable seal, blade tip incurs into the shroud, thereby reducing the gap between rotor and the shroud to a minimum. Abradable coatings are generally multiphase materials applied using thermal spray techniques. The most common three phases are metal matrix, oxide particles, and porosity. Effectiveness of seal is determined by optimum combination of properties like erosion resistance and hardness; and this is achieved by maintaining proper combination of the ingredients while manufacturing. The present study intends to develop theoretical/modeling approach to study these materials and develop design and property prediction capability in order to come up with best abradable materials. This modeling approach seems to provide consistent results and these results can be used as a reliable starting point in further coatings design.