GERMANY Metals in contact with aqueous solutions. When metals are brought into contact with aqueous solutions at room temperature there is said to be an initial or ‘incubation’ period which may be of extremely short duration, almost a transient. After this period corrosion may increase rapidly to a thousand times its initial value or more, or may decrease even more rapidly. The latter process can be followed only with a cathode ray oscilloscope. The formation of local elements is assumed to be the cause of the processes observed. The effect on corrosion is shown at the instance of aluminium of different degrees of purity. Dissolution speeds are 6 g./sq.m./day for Al 99.998% rising to 190,000 g./sq.m./day for Al 99.2%.— (F. Tödt, Werkstoffe & Korrosion, 1954, 5, (11), 430–433).
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