| 摘要 |
A method for degreasing iron, zinc or aluminum metal or an alloy comprising two or more of these metals to be processed by bringing a degreasing solution in contact with the metal to be processed, wherein said degreasing solution contains an alkali silicate, a water-soluble polycarboxylate and a nonionic surfactant and is controlled so as to satisfy the following +E,crc/1/ , +E,crc/2/ , +E,crc/3/ and +E,crc/4/ conditions. +E,crc/1/ The pH value of the degreasing solution is 10.5 or more. +E,crc/2/ The concentration of an alkali silicate is 100 ppm or more upon converting into the Si element and satisfactory for the following (a) equation: log10Y</=0.318 X+2.72(a) +E,crc/3/ The concentration of a water-soluble polycarboxylate is in a range of from 0.01 to 10 g/liter. +E,crc/4/ The concentration of a nonionic surfactant is in a range of from 0.01 to 10 g/liter.
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