Aluminium corrosion studies. II. Corrosion rates in water

Abstract

The corrosion rate of aluminium in flowing neutral waters at 50�C has been determined as a function of pH, oxygen concentration and chloride concentration. The corrosion rate, At, as total aluminium lost between the 4th and 80th day was observed to be logarithmic according to At = B log t+C with a minimum rate in the pH range 5-6, and with B c. 3 x 10-5g cm2, C c. 20 x 10-5 g cm-2 and t in days for oxygen-saturated water. Saturating the water with nitrogen or adding up to 15 mg Cl- l-1 increased the corrosion rate. It was concluded that this was due to competitive action on the oxide surface, between dissolved oxygen and chloride ions.

Reaction of aluminum powder with water in cement-containing refractory castables

“…5 It should be mentioned that in these investigations no major effect on the overall corrosion was attributed to the impurities of the aluminum specimens (0.420% Fe, 0.085% Si, 0.006% Ca). 5 The large similarity between the various corrosion stages of aluminum in water and the stages observed during H 2 generation in castables ( Fig. 1) suggests that the aluminum-water reaction is governed by the same mechanism in both cases.…”

“…The amount of aluminum reacted in the castables (in mol of Al/Al surface area), for instance, achieved levels as high as 3.7 × 10 −5 mol/cm 2 after 10 h, whereas in the corrosion experiments only 1.3 × 10 −5 mol/cm 2 of aluminum had reacted after a period of time as long as 100 days. 1,5 This can be attributed to the maximum reaction rate of almost three orders of magnitude higher for the aluminum added to castables (∼1.9 × 10 −5 mol/h cm 2 ) in comparison to the aluminum used in the corrosion study (∼7 × 10 −8 mol/h cm 2 ). 1,5 A more detailed discussion about the corrosion stages observed in the castables will be given in Section 3.4.…”

“…Due to the lack of model studies on this subject in the refractory field, these results were initially interpreted taking into account past investigations on the corrosion behavior of aluminum metal in water. 4,5 The three main corrosion stages identified in these studies were attributed to the sequential formation of a boehmite (1st stage, slow rate) and a bayerite (2nd stage, highest rate) surface layer, followed by a long term corrosion stage (3rd stage, slow rate). 5 It should be mentioned that in these investigations no major effect on the overall corrosion was attributed to the impurities of the aluminum specimens (0.420% Fe, 0.085% Si, 0.006% Ca).…”

“…4,5 The three main corrosion stages identified in these studies were attributed to the sequential formation of a boehmite (1st stage, slow rate) and a bayerite (2nd stage, highest rate) surface layer, followed by a long term corrosion stage (3rd stage, slow rate). 5 It should be mentioned that in these investigations no major effect on the overall corrosion was attributed to the impurities of the aluminum specimens (0.420% Fe, 0.085% Si, 0.006% Ca). 5 The large similarity between the various corrosion stages of aluminum in water and the stages observed during H 2 generation in castables ( Fig.…”

Fuels for research and test reactors, status review: July 1982

“…[96] This corrosion product is a multi-layered aluminum oxide and there is evidence that dissolution of at least one of these layers can have a significant effect on the corrosion rate. [97][98][99][100][101] The dissolution rate is a function of at least three different variables (temperature, pH, and refreshment rate), but there is no generally accepted model of the detailed behavior. Also, care should be taken during storage in air to keep humidity or contamination (e.g., from fingerprints) from plate surfaces, particularly if the plates have not been cleaned and passivated.…”