Residual stress in zirconia coating by EB-PVD method

Suzuki, Kenji*; Wada, Kunihiko*; Matsubara, Hideaki*; Shobu, Takahisa  ; Kawamura, Masashi*; Tanaka, Keisuke*

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 (EV-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 sin method. The measured residual stresses were -76.6 MPa for 5 rpm, -63.0 MPa for 10 rpm and -25.1 MPa for 20 rpm.