Plasma-sprayed zirconia thermal-barrier-coating containing composite transition-layer

In this paper the authors present a graded zirconia thermal-barrier-coating, which contains metal-ceramic composite transition-layer. The authors make use of research published in 1990 by Tsunekawa et al and Zhuang et al. But the application of their ideas to the design of plasma-sprayed zirconia thermal-barrier-coating, which contains composite transition-layer, with thermal expansion considered is believed to be new. It is shown that mismatch of thermal expansion coefficients between base metal and coating can seriously impair usefulness of coating as a thermal barrier. When plasma-sprayed zirconia thermal-barrier-coating containing composite material is used, it can be so designed as to make its coefficient of thermal expansion become closer and closer to that of the base metal as it gets nearer and nearer to the base metal. Under the same experimental conditions, bond strength test, bending test, cupping test and thermal impulse cycling test are conducted both for plasma-sprayed zirconia thermal-barrier-coating containing composite transition-layer and for plasma-sprayed zirconia thermal-barrier-coatings which contain metallic transition-layers. Such tests show that the zirconia thermal-barrier-coating containing composite transition-layer is superior to the zirconia thermal-barrier-coating containing metallic transition-layer.