Processing of a low-cost γ–γ′ NiPtAl coating with improved oxidation resistance
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A novel γ–γ′ (Ni solid solution—Ni3Al) NiPtAl coating was produced on advanced single-crystal (SC) superalloy N5 by electroplating of a thin Pt coating with ~ 3 μm in thickness followed by heat treatment at 1000 °C in vacuum. For comparison, a traditional γ–γ′ NiPtAl coating was also produced by electroplating of a thick Pt coating with ~ 6 μm in thickness followed by heat treatment at 1100 °C in vacuum. The novel coating has a mass gain of ~ 0.5 mg·cm−2 after 100 h 1-h cyclic oxidation at 1150 °C, showing better oxidation resistance than the traditional coating. An oxide scale mostly consisting of α-Al2O3 grew on the novel coating because the element Cr from the SC alloy substrate contributes to the formation of α-Al2O3. Pt content in the novel coating has significant effect on the oxidation resistance. The optimized Pt content in the coating is about 16 at%, which is helpful to reduce the diffusion of harmful elements from the substrate into the coating but also to reduce the cost of the coating.
Keywordsγ–γ′ NiPtAl coating Platinum Oxidation Al2O3 Superalloy
This research was financially sponsored by the National Natural Science Foundations of China (Nos. 51590894, 51425102, 51231001) and China Postdoctoral Science Foundation (No. 2017T100023).
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