| 摘要 |
PURPOSE:To reduce the chemical conversion treatment time and to improve the chemical conversion coatings by carrying out the zinc phosphate conversion treatment of metallic parts, etc., by a dipping process, specifying the composition and pH of a degreasing soln. in the degreasing stage, and incorporating a specified amt. of ferric ions in the zinc phosphate conversion coating soln. CONSTITUTION:The zinc phosphate conversion treatment of metallic parts, etc., is carried out by a dipping process, and degreasing, water washing, surface preparation, zinc phosphate conversion treatment, water washing, and drying are successively carried out. In this case, an aq. soln. kept at >=10.5 pH and contg. 10-50g/l sodium silicate-contg. alkali builder, 0.1-5g/l org. chelating agent (gluconic acid, etc.), and 0.1-5g/l surfactant (a nonionic surfactant, etc.) is used as the degreasing soln. to be used in degreasing. In addition, 5-25ppm ferric ion is incorporated in the zinc phosphate conversion coating soln., the total acidity is controlled to 25-45 points, the acid ratio is adjusted to 13-17 points, and the temp. is regulated to 45-60 deg.C. Hot water or ordinary-temp. water is used in the water washing and drying stage, and air-blowing drying is carried out after washing with water.
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