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5352 |
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Diode laser modified thermal barrier coating erosion resistance |
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Nikolay Zaitsev* / Technological Systems for Protective Coatings, Ltd., Russian Federation Ivan Mazilin / "Technological Systems for Protective Coatings"Ltd, Russia Lev Baldaev/ "Technological Systems for Protective Coatings"Ltd, Russia Victor Ovchinnikov/ Russian Aircraft Corporation «MiG», , Russia |
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Laser treatment is one of the most effective methods to improve properties of atmospheric plasma sprayed (APS) thermal barrier coating (TBC) which allows to obtain higher strain tolerance and erosion resistance due to modification of ceramic layer structure. During service TBC are often subject to abrasive attack of different particles such as dust caught outside, chips flying of the spalled coating, etc. Such an impact of abrasive attacks results in early degradation of TBC system. That is the reason why high erosion resistance is one of the desirable properties for a ceramic top coating. In the present work standard two-layer TBC system (Ni-Cr-Al-Y bondcoat and 7YSZ ceramic topcoat) was sprayed on the surface of Ni-based substrates using APS. Coatings were then subjected to laser treatment using high power diode laser source. Samples were tested on an erosion rig, which is capable to simulate high velocity gas stream with SiO2 particles. Laser treated coatings showed better erosion resistance compared to as-sprayed coatings. Main reasons for the difference are an enhanced hardness, low roughness and vertical crystal orientation of the modified layer. Impact angle was shown to affect the erosion rate. Also it should be considered that samples showed different results prior and after heat treatment in furnace. |