Mild steel sodium hydroxide

A rather different situation arises when mild steel is exposed to liquid water or dilute sodium hydroxide at 300-360°C. Here a duplex Fej04 scale is formed, consisting of an inner adherent protective film in contact with... 

In an incident involving corrosive attack on aluminium by sodium hydroxide solution, the vigorous evolution of hydrogen was noticed before a tank trailer (supposed to be mild steel) had perforated [1], Corrosion caused failure of an aluminium coupling between a pressure gauge and a pump, causing personal contamination [2],... 

Most wastes that emerge from these processes are acidic, but are neutralized with sodium hydroxide before transfer to mild steel storage tanks. The waste is first transferred to cooled tanks, where it remains for about two years until most of the short-lived fission products have decayed. The waste is then transferred to uncooled tanks. 

A 120-cm2 piece of Nafion 390 was-installed in an electrochemical cell using a Ti02/Ru02 coated titanium anode and a mild steel cathode. The current density of the cell was varied from 0.1 to 0.5 amps cm 2 over a period of several days the fluxes of the various components were measured at each current density. Figure 2 shows the variation of current efficiency with current density at constant external concentrations of sodium chloride and sodium hydroxide (that is, constant chemical potentials). It is evident that the flux of sodium ions increases relative to that of hydroxyl ions, with increasing current density. Figure 3 shows a dramatic change in the ion fluX o/h -... 

M.J. Humphries and R.N. Parkins, Stress-Corrosion Cracking of Mild Steels in Sodium Hydroxide Solutions Containing Various Additional Substances, Corros. Sci., Vol 7, 1967, p 747-761... 

The anodes that have been used include stainless steels, mild steel, lead and platinised titanium, while typical electrolytes for ferrous materials have been 0.5 M sodium hydroxide, 0.2 M sodium carbonate, 0.5 M sodium sesquicar-bonate and tap water. For bronze cannons recovered from the Mary Rose, both sodium hydroxide and sodium carbonate electrolytes were employed while pewter artefacts (plates) from the same ship were treated in similar electrolytes or in a 0.5% solution of EDTA as a sodium salt in alkaline solution. 

Figure 8.7. Effect of applied potential on failure times of 0.09% C mild steel at three temperatures in 35% sodium hydroxide solution [48]. [Reprinted with permission from Corrosion 28, No. (11), 430 (1972). Copyright NACE International 1972.]...

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