Surface behaviour in deuterium permeation through erbium oxide coatings

Abstract

Suppression of tritium permeation through structural materials is essential in order to mitigate fuel loss and radioactivity concerns. Ceramic coatings have been investigated for over three decades as tritium permeation barriers (TPBs); however, a very limited number of investigations on the mechanism of hydrogen-isotope permeation through the coatings have been reported. In this study, deuterium permeation behaviour of erbium oxide coatings fabricated by filtered arc deposition on reduced activation ferritic/martensitic steels has been investigated. The samples coated on both sides of the substrates showed remarkably lower permeability than those coated on one side, and the maximum reduction efficiency indicated a factor of 105 compared with the substrate. The different permeation behaviour between the coatings facing the high and low deuterium pressure sides has been found by the crystal structure analysis and the evaluation of the energy barriers. It is suggested that the permeation processes on the front and back surfaces are independent, and the TPB efficiency of the samples coated on both sides can be expressed by a multiplication of that of each side.

Control of substrate oxidation in MOD ceramic coating on low-activation ferritic steel with reduced-pressure atmosphere

“…The permeation reduction factors (PRFs) at 600°C were calculated to be 120-270. The magnitudes of these factors are close to those obtained for a one-side-coated PVD sample facing the low-pressure side [13]. Improvement in permeation barrier performance could also be expected by annealing an MOD coating up to 700°C in air.…”

Hydrogen gas driven permeation through tungsten deposition layer formed by hydrogen plasma sputtering

“…3, the observed hydrogen permeation fluxes were compared with the fluxes through Ni plate [3,4], W bulk [5,6], W film [7,8] and Er 2 O 3 coating [9], which were calculated by using literature data. Er 2 O 3 coating is a candidate of tritium permeation barrier.…”

Tritium permeation experiments using reduced activation ferritic/martensitic steel tube and erbium oxide coating

“…One of the remaining issues in tritium behaviors in the fusion materials is to clarify the permeation behavior at low partial pressure tritium for the interpolation to practical fusion blanket conditions. Regarding the TPB coatings, erbium oxide (Er 2 O 3 ) thin films have recently shown remarkable permeation reduction factors using a physical vapor deposition method [2]. Moreover, Er 2 O 3 coatings have been fabricated on plate substrates by not only spin-coating but also dip-coating process with a metalorganic decomposition (MOD) method [3,4].…”