The present contribution gives an overview about recent research on a TBC （thermal barrier coating） system consisted of （I） an intermetallic MCrAIY-alloy BC （bond coat） applied by VPS （vacuum plasma spraying） ...The present contribution gives an overview about recent research on a TBC （thermal barrier coating） system consisted of （I） an intermetallic MCrAIY-alloy BC （bond coat） applied by VPS （vacuum plasma spraying） and （2） an YSZ （yttria stabilised zirconia） top coat APS （air plasma sprayed） at Forschungszentrum Juelich, Institute of Energy and Climate Research （IEK-2）. The influence of high temperature dwell time, maximum and minimum temperature on crack growth kinetics during thermal cycling of such plasma sprayed TBCs is investigated using scanning electron microscopy and AE （acoustic emission） analysis. Thermocyclic life in terms of accumulated time at maximum temperature decreases with increasing high temperature dwell time and increases with increasing minimum temperature. AE analysis proves that crack growth mainly occurs during cooling at temperatures below the ductile-to-brittle transition temperature of the BC. Superimposed mechanical load cycles accelerate delamination crack growth and, in case of sufficiently high mechanical loadings, result in premature fatigue failure of the substrate. A life prediction model based on TGO growth kinetics and a fracture mechanics approach has been developed which accounts for the influence of maximum and minimum temperature as well as of high temperature dwell time with good accuracy in an extremely wide parameter range.展开更多
文摘The present contribution gives an overview about recent research on a TBC （thermal barrier coating） system consisted of （I） an intermetallic MCrAIY-alloy BC （bond coat） applied by VPS （vacuum plasma spraying） and （2） an YSZ （yttria stabilised zirconia） top coat APS （air plasma sprayed） at Forschungszentrum Juelich, Institute of Energy and Climate Research （IEK-2）. The influence of high temperature dwell time, maximum and minimum temperature on crack growth kinetics during thermal cycling of such plasma sprayed TBCs is investigated using scanning electron microscopy and AE （acoustic emission） analysis. Thermocyclic life in terms of accumulated time at maximum temperature decreases with increasing high temperature dwell time and increases with increasing minimum temperature. AE analysis proves that crack growth mainly occurs during cooling at temperatures below the ductile-to-brittle transition temperature of the BC. Superimposed mechanical load cycles accelerate delamination crack growth and, in case of sufficiently high mechanical loadings, result in premature fatigue failure of the substrate. A life prediction model based on TGO growth kinetics and a fracture mechanics approach has been developed which accounts for the influence of maximum and minimum temperature as well as of high temperature dwell time with good accuracy in an extremely wide parameter range.
