Effect of thermal cycles on structure and deuterium permeation of Al2O3 coating prepared by MOD method

Abstract

Abstract The effect of thermal cycles on the microstructure and deuterium permeation of the Al2O3 coatings prepared by the MOD method was investigated. An as-deposited Al2O3 coating showed a uniform, smooth and dense surface morphology and was composed of γ-Al2O3 and α-Al2O3 phases. After 550 °C thermal cycles, all the Al2O3 coatings exhibited good phase stability. The Al2O3 coating remained intact and dense after 100 thermal cycles, while obvious cracks appeared on the coating surface after 150 thermal cycles. Furthermore, a deuterium permeation test of the as-deposited and thermally cycled Al2O3 coatings was carried out. The deuterium permeation flux of the Al2O3 coating increased with increasing the number of thermal cycles. The Al2O3 coatings with fewer than 100 thermal cycles remained dense and had a smooth surface morphology. However, several cracks appeared on the surface of the coating after 100 thermal cycles. In particular, delamination of the coating occurred after 150 thermal cycles. Disappearance of the (400) and (441) diffraction peaks of the γ-Al2O3 was observed after the deuterium permeation tests. The microscopic mechanism of the influence of thermal cycles on the microstructure and deuterium permeation of the Al2O3 coatings was analyzed.