TEMPERATURE-DEPENDENCE OF BENDING STRENGT H FOR PLASMA-SPRAYED ZIRCONIA COATING

Plasma sprayed zirconia applying to the thermal barrier coating in gas turbine has been developing for protecting the hot parts such as blad es and nozzles from high-temperature environments. In this paper, four point bending tests under various temperature conditions are conducte d on plasma sprayed zirconia and its mechanical properties are examine d, results show that the bending strength at room temperature for plas ma sprayed zirconia is much lower than that of sintered zirconia and i s decreased with the increase in temperature. However, Weibull modulus at each temperature is relatively large and the dispersion of bending strength is very small in comparison with that of sintered zirconia. It is also clarified by the SEM observations of fracture surface that many defects such as debonding and microcrack are responsible for the lower bending strength.