Recession Behavior and Recession Rate Prediction of Silicon Nitride in Combustion Gas Flow
Isao YURI and Tohru HISAMATSU
Abstract:The influence of various basic factors of combustion gas flow conditions on the recession rate of silicon nitride has been experimentally clarified, and the recession rate equation is deduced using the dependence of influential factors on the recession rate and the mass transfer theory. The exposure tests are performed under various gas flow conditions (T = 1200-1500 , P = 0.2-0.7 Mpa, V = 40-200 m/s, PH2O = 30-90 kPa, PO2 = 20-45 kPa, t = 10 h). Recession rates mainly depend on water vapor partial pressure, pressure, gas temperature, and Reynolds number represented the gas flow conditions inside the specimen holder. The dependent on oxygen partial pressure is extremely low for silicon nitride. The recession rates of silicon nitride in combustion gas flow are expressed in the form exp(-E/RT)E(PH2O)nERe0.8/P, and the predicted recession rates of silicon nitride shows good agreement with reported exposure test results under a gas turbine condition. Key Words:Ceramics, Gas turbine, Recession characteristics, Prediction method, Silicon nitride, Combustion gas flow