The influence of Benzotriazole (BTA) and Tolyltriazole (TTA) as corrosion inhibitors for copper and brasses in 3% NaCl solutions have been investigated using infrared reflection-absorption spectroscopy, electrochemical polarization, corrosion tests and scanning electron microscopy. The protection afforded by pretreatment was tested in chloride solutions in the presence and absence of BTA and/or TTA. TTA by itself was found to be equally as effective as BTA. Combination of BTA and TTA resulted in significant improvement in the protection of these metals, particularly in acidic solutions. Contrary to BTA, TTA appeared to be an adsorption-type inhibitor for copper and brass.

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Effect of inorganic zinc rich paints on the durability of epoxy top coat was investigated in 3wt% sodium chloride solution. It was found that paint failure of epoxy top coat such as blisters was predicted by polarization resistance measurement, impedance measurement, electrode potential measurement of the coated mild steel. The coated mild steel which had no failure for 400 days hold high polarization resistance over the same period. The coated steel also kept a initial value of high impedance. The same sample showed only a slight shift of electrode potential toward the less noble direction. Epoxy top coat over zinc rich paints had no failure after 400 day service and the system was superior to the epoxy top coat which was directly applied to the blasted steel.
As a conclusion, the coating system that epoxy top coat was applied to zinc rich paint-coated steel showed the most excellent durability in 3wt% sodium chloride solution, evaluating from electrochemical measurements and the result coincided with the observation of the test panels.

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The scaling kinetics of iron in the argon-diluted sulfur dioxide gas atmospheres were investigated by thermogravimetry at 1073K in SO₂ partial pressures from 20 to 10⁵Pa; the reacted specimens were characteried by means of metallography, X-ray diffractometry, and electron microprobe analysis. The scaling kinetics varied with corrosion time, that is, (1) from linear to primary parabolic (below 10³Pa), (2) from primary parabolic to secondary parabolic (between 10³ and 10⁴Pa), and (3) only secondary parabolic (above 10⁴Pa) rate laws. The morphology of scales formed in the SO₂ partial pressures lower than 10⁴Pa showed the lamellar structure consisting of oxide and sulfide, which was produced in linear and primary parabolic periods, and in the secondary parabolic period the oxide was mainly produced. In high SO₂ partial pressures (above 10⁴Pa), the scales were composed of the oxides of wüstite and magnetite phases, though the mixture of wüstite and ferrous sulfide was observed in the vicinity of the metal/scale interface. The platinum marker located on the metal surface was found always just on the metal surface during corrosion over the whole range of SO₂ partial pressures. The linear rate constant was proportional to about 0.63 power of SO₂ partial pressure. The kinetics in the linear period was discussed from the observed linear rate constant and calculated mass fluxes of SO₂, O₂, and S₂ molecules in the gas atmosphere. Thus, the dissociation process of the adsorbed O₂ and S₂ molecules produced on the scale surface was concluded to be the rate determining step in the linear period.

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Extreme value analysis, the basic principle and application of which had been described in the book written by E. J. Gumbel, has been successfully applied to estimate the maximum pit depth on the oil tank base plate. This method is quite useful to predict corrosion failure life for such a large apparatus that detailed inspection of corrosion damage for the whole area could not be easily done due to its large surface area. Maximum pit depth distribution was determined from 10 small inspection sites chosen at random, the mean area of which was 1.85m². From the distribution the maximum pit depth for the whole area of 1.04×10³m² of oil tank base plate was estimated to be 5.56mm at 50% probability after 10 years exposure. Penetration of the maximum pit into the base plate was concluded to occur at the inspection time with high confidence because the original plate thickness of 6mm falled within 1σ control limit of the extreme value plot.

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High-temperature sulfidation of iron and steels does not seem so popular as oxidation of these alloys. Nevertheless, the sulfidation of steels is very important in the current industries. The article gives an outline on the corrosion kinetics and scale morphologies during sulfidation of iron based binary and ternary alloys as well as pure iron.
Especially, the sulfidation of some alloys is mentioned in low sulfur pressures.

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