Helium Blistering of Ceramic Coatings on Hastelloy X and Nb—1% Zr

Abstract

The surface damage of insulating ceramic coatings on Hastelloy X and Nb—1% Zr held at room temperature and at 300°C has been studied for both 100- and 250-keV helium ion irradiation for a dose range from 3.7 × 10¹⁸ to 1 × 10¹⁹ ions cm⁻². Blisters were observed after room temperature irradiation with both 100- and 250-keV helium ions. However, for irradiation at 300°C no blisters could be observed. The sharp rise in the helium permeation with temperature, observed by others for some glasses and ceramics, is thought to be responsible for this behavior. These results suggest that for the energy range studied, helium blistering has a negligible surface erosion effect on such coatings if they are operated at temperatures above 300°C.