Deuterium permeation properties of Er2O3/Cr2O3 composite coating prepared by MOCVD on 316L stainless steel

In this work, an Er2O3/Cr2O3 composite coatings on 316L stainless steel were prepared by metalorganic chemical vapor deposition (MOCVD). Effect of Cr2O3 layer on the microstructure, mechanical properties and deuterium permeation properties of Er2O3 coating was investigated. It was found grain sizes of the coatings enlarged with increasing the thickness of Cr2O3 layer. The Er2O3/Cr2O3 (80 nm) composite coating showed larger adhesion force value 9.2 N than the Er2O3 coating. The Cr2O3 layer adding could significantly enhance the deuterium permeation inhibition property of the coatings. The single-layer Er2O3 coating exhibited the minimum reduction in deuterium permeability, and the permeation reduction factor (PRF) values were in the range of 95-146 at 823-973 K. The maximum reduction in deuterium permeability was obtained from the Er2O3/Cr2O3 (80 nm) composite coating, and the PRF values were in the range of 463-206 at 823-973 K. With further increasing thickness of the Cr2O3 layer to 120 nm, the hydrogen permeation inhibition performance of the composite coating lower instead. Furthermore, apparent delamination of coating was illustrated on the single-layer Er2O3 coating after the permeation measurement, and this might be the main reason for the transformation to diffusion limiting process.