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Corrosion of ferrous metal and aluminum surfaces, in particular, is inhibited by a layer of an organic-metallic complex of a polyamine with a (i) metal oxide, or (ii) metallate ion, or (iii) water-soluble metallate salt, in aqueous systems having a pH greater than about 7. The polyamine contains at

Corrosion of ferrous metal and aluminum surfaces, in particular, is inhibited by a layer of an organic-metallic complex of a polyamine with a (i) metal oxide, or (ii) metallate ion, or (iii) water-soluble metallate salt, in aqueous systems having a pH greater than about 7. The polyamine contains at least four (4) amine groups, two of which are secondary amine groups. The effect of the N atoms stretched over the length of the polyamine produces a “caging effect”0 which immobilizes the oxide, or metallate ions, thus forming the protective layer. The organic-metallic complex deposited on the metal\s surface forms the “amine-metallic”layer which may be either an “amine-metal oxide complex”which is a coordination complex, or, an “amine-metallate complex”. The amine-metallate complex may be either an ionic complex of “amine.metallate ions”, or, a mixture of the polyamine and metallate salt which mixture is not a complex, but in solution, behaves like one, and is therefore referred to as an admixture complex of an “amine+metallate salt”. The organic-metallic complex may be present in a concentration from about 10 ppm to about 5% by wt in neutral or basic aqueous solution. In the lower range of this conc. up to about 2000 ppm, the complex is useful in aqueous process streams; in the higher range, from 2000 ppm to 5%, for a rinse for phosphated metal parts, in lieu of a conventional chromate rinse.

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A corrosion inhibiting and scale suppressing layer formed in a thickness sufficient to provide desired protection on a metal surface of a substrate in contact with an aqueous solution having a pH greater than about 7, said layer consisting essentially of a combination of an organic polyamine and a m

A corrosion inhibiting and scale suppressing layer formed in a thickness sufficient to provide desired protection on a metal surface of a substrate in contact with an aqueous solution having a pH greater than about 7, said layer consisting essentially of a combination of an organic polyamine and a metal component, said organic polyamine being a polyethyleneimine present in an amount in the range from about 10 ppm to about 5% by weight, and having at least one terminal primary amine group and intermediate plural secondary amine groups, the total number of said primary and secondary amine groups being at least 4, said polyethyleneimine being selected from an essentially linear polyethyleneimine having from 4 to about 10 repeating units, and a branched polyethyleneimine having from 4 to about 500 repeating units, wherein each polyethyleneimine is represented by a structure selected from [Figure] and [Figure] wherein, R= [Figure] n represents an integer in the range from 2 to about 500; x and y are integers, the sum (x+y) being in the range from 3 to about 2400; and, the number of tertiary amine groups are randomly distributed among the secondary amine groups; said metal component being present in an amount in the range from about 10 ppm to about 5% by weight and selected from the group consisting of (i) an oxide of an element selected from Mo and W, and (ii) a metallate ion selected from molybdate and tungstate ions; whereby a complex of said polyamine and said metal component is formed to provide said layer which is attached to said surface by interaction therewith of a group selected from a primary amine, a secondary amine, a metallate ion and a metal oxide; and at least said primary amine group is anchored directly to said metal surface.