Thermal shock behavior of EB-PVD thermal barrier coatings

Yttria partially stabilized zirconia ceramic top coat was deposited on a sputtered NiCrAlY bond coat by electron beam physical vapor deposition (EB-PVD) and the thermal shock behavior was studied at different temperatures. The results showed that the columnar structure of the ceramic top coat enhanced the ability of the TBC to resist thermal shock. However, the thermal shock life of the TBCs depended on the thermal shock temperature, so did the thermal shock spallation mode. At 1050 degrees C or lower temperature, the thermal shock life was long, and the spallation of the coating initiated at the edge or near the hole of samples. The TBCs failed only with the ceramic top coat spalling partially by partially and the spallation area had little effect on the un-spallation area. At 1100 degrees C and 1200 degrees C, the thermal shock life was shortened. The central coating was arched outward first during thermal shock cycling, and then the ceramic top coat spalled at a large area, just a little ceramic coating remained at the edge of the samples. When the temperature reached 1300 degrees C, the entire ceramic top coat spalled just only after one thermal shock cycle. (C) 2007 Elsevier B.V. All rights reserved.