Study on the High-Speed Rubbing Wear Behavior Between Ti6Al4V Blade and Nickel–Graphite Abradable Seal Coating

The wear behavior of Ti6Al4V blade rubbed against nickel–graphite (Ni–G) abradable seal coating was studied with a high-speed rub test rig. According to the test results acquired at different incursion per passes and linear speeds, blade wear increased with the increment of linear speed at a fixed incursion per pass. With incursion per pass increasing, blade wear increased when linear speed was fixed at 30 m/s, while decreased at 90 and 150 m/s. Referring to the macromorphology observation, scanning electron microscopy (SEM) and dispersive X-ray spectroscopy analyses of the wear scars, rubbing at 30 m/s, microcutting and microploughing with coating adhesion was the main blade wear mechanism while spalling accompanied by densification was the main coating wear mechanism. Rubbing at 90 and 150 m/s, plastic deformation was the main blade wear mechanism while transfer mixed layer that resulted from blade transferred was identified as the main coating wear mechanism. Quantitative analysis of coating densification and microhardness detection of the transfer mixed layer indicated that high coating densification made great contribution to low blade wear at 30 m/s and aggravated blade wear at high linear speed was due to the high frictional heat and the resultant high-hardness transfer mixed layer. It could therefore be concluded that high linear speed guarantees enough frictional heat output while low incursion per pass is responsible for the accumulation of frictional heat.