Influence of polyimide coating and texturing on the wear behavior of Inconel X-750 in air foil journal bearing using K-means clustering

Abstract

In this study, the influence of texture and coating on wear behavior of Inconel X-750 (IncX-750) is analyzed for Air Foil Bearing (AFB) applications. AFB is used for high-speed rotating machines. But there are challenges in controlling wear during the start-stop condition, at which, the top foil of the bearing will undergo frequent contact with the journal. To improve the wear behavior, texture and polyimide (PI) coating are introduced on the surface of IncX-750 and pin-on-disc (POD) test is conducted to determine the wear behavior. The three ranges of load and speed are taken as input controlling parameters and the Co-efficient of friction (COF) and wear are obtained as outputs. The COF as 0.361 and wear as 15μm shows that the coated non-textured (CNT) have lower friction and improved wear resistance. Additionally, K-means clustering using Python supported that the CNT specimens have lower wear compared with other specimen for different speed and load ranges. The crystalline phase, functional groups, wear track, and wear zone on the specimen's sliding surface are all investigated using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, optical microscopy, and scanning electron microscopy (SEM), respectively. The coating exhibits various crystalline structures and a stable layer, as seen by the C = O and N-H bonds found in the FTIR and XRD data. The SEM pictures demonstrate how effectively the PI structure adheres to the substrate.