Influence of Impurity Content on Recession Characteristics of Sintered Yttria Stabilized Zirconia in Combustion Gas Flow
Isao YURI, Shin NAJIMA and Tohru HISAMATSU
Abstract:In order to examine the influence of impurity content on the characteristics to prevent the recession of Yttria Stabilized Zirconia in combustion gas flow, sintered Yttria Stabilized Zirconia (ZrO2) specimens with different impurity (Al2O3 or SiO2) contents were prepared and exposed under a combustion gas flow condition (T = 1500 , P = 0.3 Mpa, V = 150 m/s, PH2O = 35 kPa, t = 5-20 h). As a result, the significant weight loss of high purity ZrO2 was not found, and it was shown that high purity ZrO2 has superior characteristics to prevent the recession and is promising candidate materials. In addition, the impurity content influences on the recession characteristics, and the weight loss of ZrO2 with more impurity increases as the impurity content increases. Thus, in order to prevent the recession, the increase of purity is required. Furthermore, impurity contained in ZrO2 disappeared selectively from the surface under the combustion gas flow. The disappearance of impurity was also observed under the surface, and the thickness of the layer without impurity under the surface increased according to the exposure time. Key Words:Ceramics, Gas turbine, Recession characteristics, Yttria stabilized zirconia, Impurity content