Al₂O₃ was deposited as a top coat on a standard 7YSZ layer (or layers) by means of EB-PVD technique and the corresponding morphology of the Al₂O₃/7YSZ coatings was studied in detail. This multi-layer TBC system was tested against calcium-magnesium-aluminium-silicate (CMAS) recession by performing infiltration experiments for different time intervals from 5 min to 50 h at 1250 °C using two types of synthetic CMAS compositions and Eyjafjallajökull volcanic ash (VA) from Iceland. The results show that the studied EB-PVD Al₂O₃/7YSZ coatings react quickly with CMAS or VA melt and form crystalline spinel (MgAl_2-xFe_xO₄) and anorthite (CaAl₂Si₂O₄) phases. The presence of Fe-oxide in the CMAS has been found to be key element in influencing the spinel formation which was proved to be more efficient against CMAS sealing in comparison to the Fe-free CMAS compositions. Even though a rapid crystallization was assured, shrinkage cracks in the EB-PVD alumina layer produced during the crystallization heat treatment have proven to be detrimental for the CMAS/VA infiltration resistance. To overcome these microstructural drawbacks, an additional alumina deposition method, namely reaction-bonded alumina oxide (RBAO), was applied on top of EB-PVD Al₂O_3. RBAO acts as a sacrificial layer forming stable reaction products inhibiting further infiltration.

的Al ₂ ö ₃沉积作为标准7YSZ层（或层）通过EB-PVD技术的装置和Al的相应形态学上的顶涂层₂ ö ₃ / 7YSZ涂层进行了详细研究。通过使用两种类型的合成CMAS组合物和Eyjafjallajökull火山灰（在1250°C下进行5分钟至50 h的不同时间间隔的渗透实验），对该多层TBC系统进行了抗钙镁铝硅酸盐（CMAS）衰退测试。 VA）来自冰岛。结果表明，所研究的EB-PVD Al ₂ O ₃ / 7YSZ涂层与CMAS或VA熔体快速反应并形成结晶尖晶石（MgAl _2-x Fe _x O ₄）和钙长石（CaAl ₂ Si ₂ O ₄）相。已经发现，在CMAS中Fe-氧化物的存在是影响尖晶石形成的关键元素，与不含Fe的CMAS组合物相比，事实证明，尖晶石的形成对CMAS密封更有效。即使确保了快速结晶，但事实证明在结晶热处理过程中产生的EB-PVD氧化铝层中的收缩裂纹不利于CMAS / VA渗透性。为了克服这些微结构缺陷，在EB-PVD Al ₂ O ₃之上采用了另一种氧化铝沉积方法，即反应结合氧化铝（RBAO）_。 RBAO充当牺牲层，形成稳定的反应产物，抑制了进一步的渗透。