Thermal shock and tritium resistance of SiO2 coating on the inner wall of 316L stainless steel pipeline

Abstract

Tritium permeation is an essential challenge that should be solved in fusion reactors. In this study, the inner wall SiO2 coating of the 316L stainless steel pipeline for tritium permeation barrier (TPB) is prepared by slurry-spraying method. The microstructure, phase composition, thermal shock resistance, and hydrogen permeation resistance of the SiO2 coating are investigated. Results show that the coating is amorphous SiO2, and the coating is bonded well to the substrate and the thickness of the coating is about 10–15 μm. After six thermal shock treatments, the SiO2 coating exhibit good thermal shock resistance stability below 700 °C. Results from the hydrogen penetration test indicate that the hydrogen resistance capability of the SiO2 coating is 16-fold higher than that of the 316L stainless steel substrate. Hydrogen resistance is also 6-fold more stable than that of 316L stainless steel. These characteristics improve significantly the hydrogen resistance performance of the 316L stainless steel substrate.