An influence of self-association of high molecular-weight amine-type corrosion inhibitors upon their chemisorption on a metal has been studied. In the earlier report, it has been also pointed out that ability of the adsorption decreased when intermolecular association of the inhibitor occurred with an other proton donor or acceptor. Two types of intermolecular association can be assumed to occur, (1) between the inhibitor and a proton donor and (2) between the inhibitor and a proton acceptor.
Extents of these associations were determined with infrared adsorption spectra, and simultaneously, inhibition efficiencies were obtained in the corrosion tests conducted in 5% hydrochloric acid with filmed mild steel test coupons dipped into carbon tetrachloride solution of the inhibitor associated or not. The inhibitors employed are 2-n-dodecyl pyrrole (I), N-n-dodecyl pyrrole (II), and dimethyl cetyl amine (III).
When II or III was associated with other proton donor such as methyl alcohol, pyrrole, phenol, or acetic acid in carbon tetrachloride, the inhibition efficiency was found to decrease. This result indicates that the association causes the chemisorption ability of inhibitor to lessen since active hydrogen of the proton donor blocks an unshared pair of electron of the inhibitor with hydrogen bond. Increasing efficiencies of these inhibitors in high concentration of acetic acid solution, however, may suggest a possibility of the chemisorption of inhi bitor associated with it.
The low inhibitions were observed in the tests conducted with the coupons filmed in the solution containing I and such a proton acceptor as dioxane or triethylamine. Though an association between the inhibitor and the proton acceptor was determined to take place, it seems unreasonable to assume that the decrease of inhibition depends upon the association, because of no blockade at the unshared electrons of the inhibitor.

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Excellent properties of Al-Zn-In anodes have been reported (Reference 1). But for the purpose of obtaining actual performance data of Al-Zn-In anodes in sea water ballast tanks, field tests and laboratory works concerned were carried out.
Several Al anodes of different compositions were tested under the same condition for comparison.
The results and conclusions obtained are as follows:
1) Comparing with the other alloy anodes, the Al-Zn-In anodes have superior characteristics in both field tests and laboratory tests.
2) The result of potential measurement in the actual vessels showed very uniform distribution, and overprotection was not observed.
3) The practical data of the current output of the anodes and the life of anodes taken from the actual ballast tanks were very close to the estimated values.

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Recently the phenomenon that Ti was easily attacked by stress corrosion cracking in methanol containing HCl was found by the present authors. And now a study was accomolished quantitatively on the stress corrosion cracking of Ti in alcohol solutions. The stress corrosion cracking of Zr was also studied considering its similarity in chemical behavior to Ti.
The stress corrosion cracking of Ti occurs in methanol solution containing HCl or H₂SO₄, and that of Zr is observed in methanol containing HCl, H₂SO₄ or HCOOH and in ethanol containing HCl.
In HCl-alcohol solutions it is also observed that the larger the molecular weight of alcohol is, the longer life the metals have.
Addition of water to HCl-methanol solution prevents the stress corrosion cracking of Ti and Zr. Critical concentration of water in 0.4% HCl-methanol solution is about 1.5% for Ti, and about 3% for Zr. To prevent the stress corrosion cracking by stress relief, annealing temperature should be selected higher than 500°C for Ti and 450°C for Zr.

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