Yasir, Sarah , ENDRINO ARMENTEROS, JOSÉ LUIS, Guillen, Elena , Aria, Adrianus Indrat
No
Emerg. Mater.
Article
Científica
0.648
01/12/2021
000734140300001
2-s2.0-85121635320
Corrosion behaviour of stainless steel 347 was investigated in a molten nitrate salt (60 wt% NaNO3 + 40 wt% KNO3) immersion at 565 degrees C for up to 3000 h. A growth of stratified oxide layers consisting of NaFeO2, Fe2O3 and Fe3O4 was observed on the stainless steel surface with a constant gravimetric corrosion rate of 0.4 mu m/year. The feasibility of using Ni3Al coatings deposited by means of air plasma spray for suppression of corrosion was investigated. Ni3Al coatings were observed to undergo a fast oxidation with a corrosion rate of similar to 2.7 mu m/year in the first 500 h, and subsequently stabilise between 500 and 3000 h with no observable changes in microstructure, composition and weight at a corrosion rate of similar to 0.02 mu m/year. The results presented in this study strongly suggest that Ni3Al coating suppresses the formation of oxide layers on the surface of stainless steel substrates and can be used as protection against corrosion in the presence of molten nitrate salts, which is of relevance to thermal energy storage applications.
Molten nitrate salts; Stainless steel corrosion; Ni3Al coatings; Air plasma spray; Corrosion resistant coatings