基板回転ＥＢ－ＰＶＤ遮熱コーティングの微構造と残留応力

概要

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CoNiCrAlY was pressureless plasma-sprayed on a substrate of nickel-base superalloy as a bond coating. Under the substrate rotation, zirconia with 4mol% yttria was coated as the top coating by the electron beam-physical vapor deposition (EB-PVD). The rotation speed of the substrate was 5, 10 and 20rpm. The top coating was made by the columnar structure which consisted of the core part and the peripheral part. The top of the core part had a pyramidal shape made by piling up the zirconia (111) planes. The peripheral part showed feather-like structure, which was made by growth of the zirconia <100> and <111> directions. For the specimen with 20rpm, the in-plane residual stress was small within the range from –20 to 30MPa, the out-of-plane residual stress was a very small compression. By the increase in the rotation speed, the column becomes thick and the inter-columnar space becomes large. The substrate rotation is useful for the reduction of the residual stresses in the EB-PVD thermal barrier coating.