Design and development of a cost-effective methodology for tribological evaluation of thermally sprayed abradable systems

Thermally sprayed abradable coatings are commonly employed as clearance control materials within gas turbine engines to minimize the clearance between the stationary and rotating parts, which in turn, improves efficiency and operational safety. While a significant amount of research has been performed on the development of novel plasma sprayed abradable coating over the last few decades, there is limited work focusing on the wear mechanisms within the abradable coatings-blade tip interaction as well as the interfacial process under application relevant contact conditions. Thus, the main purpose of this study is to design a cost-effective test rig methodology in order to assess different thermally sprayed abradable coatings and their interactions with titanium blade tips, simulating an application relevant environment. The testing rig has the capability of evaluating different abradable coating systems, it has a wide range of inputs and outputs, such as blade tip velocity, incursion rates, incursion depths, contact forces, cutting temperatures, and smoothness/roughness of cutting. Throughout this study, different thermal spray abradable coatings are explored in terms of their wear behaviour. Ex-situ analysis is performed on the worn surfaces in order to provide a better understanding of the interfacial processes for the various abradable systems.