| 摘要 |
PROBLEM TO BE SOLVED: To provide a corrosion inhibitor which has low toxicity when used in a cooling water system, does not cause environmental contamination, is also free from scaling and exhibits excellent corrosion inhibiting effect to a ferrous metallic material even if its amt. to be used is small and to provide a corrosion inhibiting method. SOLUTION: This corrosion inhibitor for ferrous metal in a cooling water system contains a compd. (component A) selected from 2-phosphonobutane-1,2,4- tricarboxylic acid and the salt thereof, 1-hydroxyethylidene-1,1-diphosphonic acid and the salt thereof and a phosphonium compd. (component B) as effective components. To the inside of the cooling water, the component A and the component B are added in the ranges of, by weight, (1:100) to (100:1), furthermore (1:10) to (30:1), particularly (1:2) to (5:1) in such a manner that the total of the effective components is controlled to 1 to 1000 mg/L, preferably to 5 to 100 mg/L.
|
