A new zinc alloy, available under the trade name of Hydro-T-Metal, has recently been developed for use in architectural, structural and other applications. Because corrosion resistance of this zinc-copper-titanium alloy was unknown, an atmospheric exposure test and other corrosion tests were carried out.
Results of atmospheric exposure test for one year are as follows:
1) Corrosion resistance of Hydro-T-Metal is equal to that of rolled zinc, coating layer of galvanized steel and high-purity zinc.
2) In urban or industrial atmosphere, average penetration rate of Hydro-T-Metal is less than 3μ/yr and also nearly equal to that of brass (60/40).
3) Among the metals exposed, stainless steel showed the best resistivity in all six locations; on the other hand, mild steel was the worst. Pitting corrosion of aluminum was observed, mainly on the back of the specimen panels.
Results of other corrosion tests, such as a test on the effect of pH on corrosion rate and immersion tests in corrosive media, also show that corrosion resistance of this alloy is almost equal to that of rolled zinc.

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To learn the behavior to soil stress, a soil stress test was carried out with various protective coating and wrapping materials for underground pipeline.
The results obtained were as follows:
(1) Among the coating materials, coal-tar enamel showed the best resistance, the asphalt enamel ranked the second and blown asphalt the third.
(2) As for the wrapping materials tested, jute cloth was a little better and glass cloth was a little worse. The others held about the same rank between jute and glass cloth.
(3) No coating without reinforcing wrappers showed good resistance.
(4) Coatings covered with whitewash showed higher resistance against soil stress than those without it, thus whitewash was effective to relieve soil stress.
(5) Polyethylene lining slid through the surrouding clay, and therefore it withstood well soil stress.

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This investigation was made to evaluate the corrosion inhibiting effects of three-component inhibitor for mild steel in HCl. The results were as follows.
(1) One component of the inhibitor, Cu²⁺, generally accelerates the dissolution of mild steel in acid medium. However, Cu²⁺ was found to improve the corrosion inhibiting effect under its combination with thiourea and urotropine in suitable ratios.
(2) At low inhibitor concentration, the inhibitor showed the corrosion inhibition of higher than 99%.
(3) At 0.2% inhibitor concentration, the composition of the inhibitor showing the lowest corrosion rate was Cu²⁺ 0.003%, thiourea 0.057-0.097% and urotropine 0.10-0.14%.
(4) The effect of temperatures on the corrosion inhibition was not observed in the range of 30°C-80°C.
(5) The corrosion inhibiting effect of the inhibitor in H₂SO₄, H₃PO₄ or HSO₃NH₂ was as excellent as in HCl.
(6) The corrosion inhibiting mechanism was further studied by the rapid polarization characteristics.

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