| 摘要 |
<p>1327567 Treating Al surfaces M N MAROSI 14 March 1972 [14 July 1971] 11838/72 Heading C7U Corrosion-resistance of Al is improved by treatment with an aqueous solution comprising (1) sulphanic acid, (2) a carboxylic acid containing 3 or more carboxyl groups, (3) a K salt of a halogen-containing acid, and (4) an anionic detergent. A composition for the above contains 10-60 wt. per cent of (1), 10-60 wt. per cent of (2), 2-30% of (3) and 0À5-15% of (4), and is used in aqueous solution. Typically, (2) is citric acid, (3) is KHF 2 , and (4) is Na alkyl aryl sulphonate, and a typical treatment procedure is (a) cleanse in solution of non-ionic detergent, (b) treat with NaOH, e. g. 2-20% solution at ambient temperature to 135‹F. for 1-6 minutes, (c) rinse, (d) treat for 2-10 min. in a 2-20% solution of 1-3À5 wt. parts Na 2 Cr 2 O 7 , 2-6 parts NaHF 2 and 10-20 parts H 2 SO 4 (e) rinse (f) treat in the above solution, e.g. at 3-25% concentration, pH 5-6À8, for 5-30 min, and (g) rinse. Optionally the treated plate is dipped in resin solution at pH 9 for 2-3 min. and baked at 250‹-350‹F. for about 10 min.</p> |
