Design and Development of Cost-Effective Equipment for Tribological Evaluation of Thermally Sprayed Abradable Coatings

Thermally sprayed abradable coatings are essential for enhancing gas turbine engines' performance, as they are commonly used for clearance control purposes. Abradables act as protective barriers between the stationary casing and rotating blades. However, evaluating the abradability performance of novel coatings is challenging, because it is typically very costly and time-consuming. Thus, the goal of this project is to create a cost-effective test rig that can evaluate and pre-screen different thermally sprayed abradable coatings and understand how they interact with titanium blade tips under application-relevant conditions. The rig is capable of providing various inputs and outputs, including blade tip velocity, incursion rates, incursion depths, reaction forces, and interfacial temperatures. Aiming to validate the rig, a detailed dynamic evaluation was conducted, as well as abradability tests on aluminum, thermally sprayed polyester, and AlSi-40Polyester abradable coating. The reaction forces for aluminum and polyester were overall higher when compared to AlSi-40Polyester. However, thermally sprayed polyester showed the highest interfacial temperatures of all materials tested. The difference in the reaction forces and interfacial temperature correlates well with the different wear mechanisms and thermal conductivities. Overall, the equipment showed to be a promising pre-screening methodology to evaluate and develop novel thermally sprayed abradable coatings.