Cailiao Baohu (Aug 2023)
Corrosion Characteristics of TA9 Alloy Layer on Ammonia Condense Separator Tube Sheet under Ammonia Environment
Abstract
According to the corrosion damage of heat exchange tube plate of ammonia condense separator in coking ammonium sulfide production，the corrosion resistance characteristics of the surface passivation film of tube sheet TA9 alloy were studied by total immersion test and electrochemical analysis.Using scanning electron microscope (SEM) and X-ray energy dispersive spectrometer (EDS)，the corrosion products of samples after total immersion test were analyzed under different temperature conditions in ammonia solution containing S2-，Cl-，F-anions or a mixture of these anions，respectively.The corrosion rate of TA9 alloy and the corrosion resistance characteristics of the surface passivation film were investigated using an electrochemical workstation.Results showed that the general corrosion and pitting corrosion of TA9 alloy gradually increased with the increase of temperature，and there was no obvious difference in the macroscopic morphology of corrosion under the action of different anions at same temperature and the corrosion products were titanium oxides.The corrosion rate of the TA9 alloy was greatly affected by temperature.In an ammonia aqueous solution mixed with three anions，when the temperature was increased from 20 ℃to 90 ℃，the corrosion rate increased from 1.059 97 μm/a to 10.619 74 μm/a，so the corrosion rate increased nearly 10 times.As the temperature rose to 50 ℃，the protective performance of the passivation film to the material decreased.At the same temperature，when fluoride ions existed alone，the resistanceRof the passive film on the electrode surface changed significantly，and the redox reaction on the electrode surface was the most violent，resulting in the fastest dissolution rate of the passivation film on the electrode surface and the highest corrosion rate of TA9 alloy.
Keywords
