Abradability is one of the most important properties when assessing the performance of seal coatings.To reflect the comprehensive service performance of seal coatings, the abradability was investigated using a series of high-temperature and high-speed friction experiments to simulate the actual working conditions of an aircraft engine.A Ti2AlNb dummy blade was rubbed against the coating with incursion rates of 5,50, and 480 um/s to represent the different working states of an engine. Rubbing between rotary blades and abradable seal coatings at slow incursion rates occurs in all gas turbines, and represents the interactions due to the thermal and centrifugal growth of materials as the rotor spins up and the temperature increases. Rubbing at a fast incursion rate represents severe rubbing interactions due to significant and sudden loading conditions, such as those during roughlandings or fighter maneuvers. Figure 1 shows the surface morphology of the wear scars of Ti2AlNb dummy blades and layered seal coatings after the abradability tests.Wear was observed on both the coatings and blades under all test conditions, but no peeling or block-dropping phenomena were observed on the coatings. The wear scar contour was regular without serrated edges, and the color of the scraped surface was similar to that of the nonscraped surface.All these results indicate that the seal coating has good abradability under the test conditions.
Fig.1 Macromorphologies of the layered seal coatings(as-sprayed) and Ti2AlNb blades after abradability tests
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