Unveiling the influence of nickel on the erosion and the tribological performance of AlSi-based abradable coatings

Abstract

The efficiency of gas turbine engines can significantly be enhanced by reducing the clearance between stationary and rotating parts. AlSi-polymer composite abradable coatings are commonly employed for such applications to serve as sacrificial materials while maintaining the pressure within compressors and seals. However, these coatings can face premature failure during operation, particularly due to corrosion and erosion. More specifically, due to the ductile behavior of AlSi-polymer-based abradables, the erosion rates at low impingement angles are particularly high. Thus, there is a strong desire to develop an abradable system capable of maintaining high erosion resistance at various impingement angles while maintaining suitable abradability (i.e., high wear of the abradable during interaction with the blade tip). The main purpose of this study is to critically evaluate the influence of Ni in AlSi-polymer-based abradable coatings on their erosion and tribological performance. The AlSi-polymer powders were mechanically mixed to develop the powders that were subsequently deposited using atmospheric plasma spray (APS). Microstructure analysis using field emission scanning electron microscopy (FESEM) and HR15Y hardness tests was employed to assess the microstructural and mechanical properties of the coating. Ball-on-flat, ball-on-disk, and air jet erosion tests were performed, followed by ex situ surface analysis to elucidate the wear mechanism. The results revealed that the incorporation of Ni preserved the lamellar microstructure characteristic of AlSi and polyester abradable coatings, while concurrently decreasing average wear rates at lower impingement angles, as observed throughout the erosion tests.

Graphical Abstract