Evaluation of corrosion resistance of amorphous Fe-Ni-Cr-Ta alloys in hot concentrated sulfuric acid solution

It is known that the heat exchanger tubes exposed to severely corrosive conditions including sulfuric acid and hydrochloric acid in waste incineration plants. Therefore, there is a pressing need for a new materials with much higher acid corrosion resistance than that of conventional dewpoint-corrosion-resistant steel and stainless steel. In this study, amorphous Fe-Ni-Cr-Ta alloys prepared by using a sputtering technique were evaluated by immersion tests in a high temperature concentrated sulfuric acid solution, and the corrosion scale formed on the alloys was analyzed using x-ray photoelectron spectroscopy. The corrosion resistance of the amorphous Fe-Ni-Cr-Ta alloys was found to be 1000 times higher than that of Type 316L stainless steel. In addition, thin layers which contained a large amount of Ta and Ta compound were found. This surface Ta rich layer was considered to contribute for increasing of corrosion resistance.