Multi-layer structured AlN/Er2O3 coating: Enhanced thermal stability and hydrogen isotope permeation resistance

AlN/Er2O3 multi-layer coatings, as a novel hydrogen isotope permeation barrier for nuclear reactor and hydrogen energy field, were prepared by magnetron sputtering coupled with metal-organic decomposition on the surface of reduced activation ferrite/martensitic steel. The thickness of the Er2O3 layers was adjusted by spin coating several times, the adhesion of the layers was tested with a micron scratch tester, and the microstructure and surface composition of the layers were analyzed by TEM and XPS. The results indicate the absence of evident crack holes on the coating surface, uniform distribution of elements without segregation, and satisfactory densification. In comparison with the individual Er2O3 coating, the multi-layer coating incorporating AlN as the interlayer exhibits enhanced adhesion strength, which could effectively mitigate the thermal mismatch phenomenon of Er2O3 under high temperature conditions. Electrochemical hydrogen permeation and high temperature gas pressure driven deuterium permeation tests demonstrated that the permeability resistance of the AlN/Er2O3 coating does not linearly increase with its thickness. The hydrogen permeation reduced factor of the coating reaches its maximum value when the thickness of the Er2O3 coating is 1500 nm.