Residual Stress in Zirconia Coating by EB-PVD Method
Kenji SUZUKI, Kunihiko WADA, Hideaki MATSUBARA, Takahisa SHOBU, Masashi KAWAMURA and Keisuke TANAKA
Abstract:The Ni-based superalloy IN738LC was used as the substrate material, and CoNiCrAlY powder was pressureless plasma-sprayed on the substrate as the bond coating. Zirconia was coated as the top coating by the electron beam-physical vapor deposition (EB-PVD) method. In the EB-PVD process, the specimens were kept at 1223 K and rotated with 5 rpm, 10 rpm and 20 rpm. According to the microscopic observation and the result of the pole figures, the top coatings had a columnar structure, which was made by the piling up of (111) planes. The cross section of the column had a diamond shape, and its diagonal was parallel to the rotation axis. The residual stress on the surface of the top coatings was evaluated by the X-ray diffraction method. Each diffraction profile was separated into the 133 and the 331 peak, and the residual stress was measured by the sin2ƒÕ method. The measured residual stresses were -76.7 MPa for 5rpm, -63.0 MPa for 10rpm and -25.1MPa for 20rpm. Key Words:Thermal barrier coating, Electron beam-physical vapor deposition, X-ray stress measurement, Residual stress, Zirconia