Preparation and characterization of T-permeation barrier on RAFM steel: Influence of HDA melt composition and superheat

The present work aims to prepare an Al2O3/Fe-Al-Si Tritium Permeation Barrier (TPB) on Reduced Activation Ferritic-Martensitic Steel (RAFMS) an ideal material for Test Blanket Module (TBM) by employing Hot Dip Aluminizing (HDA), annealing and oxidation processes. Hydrogen adsorption/desorption behavior of barrier was tested using electrochemical and thermal spectrometry techniques for qualitative determination of H2 permeation resistance of barrier coating. The results confirmed a five-time increase in permeation resistance of RAFMS with coating compared to uncoated RAFMS. Three different HDA melts with varying Si concentration of 1%, 6%, and 11% were used for understanding the impact of Si concentration in the Al melt and the superheat of the Al melt on the microstructure, hardness, adhesion strength, permeation and corrosion resistance of the HDA and the oxidized HDA coatings.