Study On Corrosion Performance Of Aluminum Alloy5052with Boiler Water

Aluminum alloys have good thermal conductivity, mechanical properties,corrosion resistance and low density, occupying an irreplaceable role in chemicalindustry. In this paper, potentiodynamic polarization test, electrochemical impedancespectroscopy (EIS) electrochemical techniques and scanning electron microscopy(SEM), EDS spectra materials research tools were used to study the corrosionbehaviors of aluminum alloys5052in different conditions of boiler water, as well asthe heat transfer and corrosion resistance of aluminum radiator was investigated by adynamic evaluation apparatus, laying the foundation for the preparation andapplication of aluminum radiator.The corrosion behavior of aluminum alloy5052(AA5052) in differentconditions of simulated boiler water as well as the average corrosion depth ofAA5052immersing in different solutions were studied. Under the experimentalconditions, the open circuit potential of AA5052decreased with the rise oftemperature. In aerated condition, pitting corrosion occurred. In deaerated condition,the aluminum alloy surface had been in a passive state, the corrosion current densityand the passive current density increased gradually with the increase of temperature.However, at different temperatures, the corrosion current density and the passivecurrent density were higher in deaerated condition than those in aerated condition.Corrosion of the alloy in aerated condition is very slight, and the average corrosiondepth changed little with temperature. In deaerated condition, general corrosionoccurred, the corrosion resistance degenerating significantly by temperature and theaverage corrosion depth increasing rapidly. The corrosion potential shiftednegatively, passive current density increased with the increase pH value but the alloykept in the passive state in all pH measured. Pitting corrosion occurred when Fe3+existed in the solution, and the pitting potential dropped with the rise of Fe3+concentration. In tap water and simulated seawater, aluminum alloy was prone topitting corrosion. Pitting potential in the seawater shifted negatively by1V than thatin tap water. Capacitive arc diameter decreased with the increase of pH, Fe3+concentration and the salinity, indicting the passivation film on the alloy surface thinning. The corrosion of the alloy intensified in simulated boiler water with higherpH; the alloy suffered obvious pitting corrosion at10ppm of Fe3+; the alloy was alsoprone to pitting corrosion in simulated seawater.The corrosion resistance and heat transfer performance of aluminum radiatorwas tested by a dynamic evaluation apparatus. Under the experimental conditions,the static coupon corrosion rate was0.0060mm/a, and corrosion rate ofelectrochemical test was0.0184mm/a. The aluminum radiator slightly corroded. Thealuminum material had no distortion and no leakage under1.8MPa pressure for10min, in line with national requirements. The thermal performance test showed thealuminum radiator reached the standard heat release capacity of nationalrequirements with a heat release capacity of1537W.