重型燃气轮机用La2(Zr0.7Ce0.3)2O7/YSZ双层热障涂层热循环性能研究

Thermal Cycle Behavior of La2(Zr0.7Ce0.3)2O7/YSZ Double-layer Thermal Barrier Coatings for Heavy Duty Gas Turbines

重型发电燃气轮机低排放、高效率的发展目标,要求燃气轮机透平的进气温度不断提高。热障涂层作为保护金属热端部件的重要手段,是实现这一目标的关键技术之一。目前世界上最先进的J级燃气轮机的透平进口温度已经达到1600℃,热端部件表面温度超过1250℃,传统的YSZ热障涂层已经不能满足这一发展需求,因此迫切需要开发温度更高、热导率更低的新型热障涂层。本文对La2(Zr0.7Ce0.3)2O7(以下简称LZ7C3)热障涂层在重型发电燃气轮机中的应用进行了初步验证。结果表明,LZ7C3涂层具有比常规YSZ热障涂层更低的热导率(0.79~0.48Wm^-1K^-1,相对传统YSZ涂层下降30%以上),且在1250℃的高温火焰台架试验中表现出优良的热循环寿命(>7370次),具有良好的应用前景。

Gas inlet temperature has been increasing for power generation gas turbines in the pursuit of lower emission and higher thermal efficiency.Thermal barrier coating system(TBCs),which can protect the metallic components from hot gas,is one of the most essential technologies to achieve the target.State of the art gas turbine of J class gas turbine has improve the turbine inlet temperature to 1600℃,which means that advanced TBCs with lower thermal conductivity and better high-temperature stability than current commercial Y2O3 partially stabilized ZrO2(YSZ)TBCs must be developed.In this paper,a preliminary study was undertaken to evaluate the possibility of applying La2(Zr0.7Ce0.3)2O7(LZ7C3)based TBCs for the gas turbines with higher turbine inlet temperature.Results showed that the thermal conductivity of plasma sprayed LZ7C3 coating decreased from 0.79 Wm-1K-1 at room temperature to 0.48 Wm^-1K^-1 at 1000℃,which was much lower than those of traditional YSZ coating.Gas burner thermal cycling results showed that the lifetime of LZ7C3/YSZ double-ceramic-layer TBCs at operating temperatures 1250℃was more than 7370 cycles.The preliminary results meant that LZ7C3 is a promising TBCs material for future ultra-efficient and low-emission turbine systems.