| 摘要 |
1,241,296. Anodizing aluminium. ALCAN RESEARCH & DEVELOPMENT Ltd. Nov. 11, 1968 [Nov. 24, 1967 (2)], Nos. 53698/67 and 53699/67. Heading C7B. A coloured anodic oxide coating free from spalling is produced on an aluminium metal or base alloy surface by anodizing the surface, e.g. in 15% H 2 SO 4 solution using D.C., then colouring the anodized surface in an aqueous acidic bath containing a Ni, Co, Cu, Ag or Pb salt, or an oxide or salt of Se, Te or Mn, and including, to reduce spalling, at least 100 ppm of Mg or (except where the bath includes Ni or Co) Al ions, using A.C. and a counter-electrode e.g. of graphite or the same metal as the colouring ions in the bath. Preferably 2-40 g/l or MgSO 4 7H 2 O or Al 2 (SO 4 ) 3 18H 2 O is added to the bath. Examples of bath compositions are: (1) nickel or cobalt sulphate, boric acid, magnesium sulphate or borate, and optionally ammonium sulphate (or as nickel ammonium sulphate); (2) copper sulphate, sulphuric acid, and magnesium or aluminium sulphate; (3) lead acetate, acetic acid, and magnesium or aluminium acetate; (4) silver nitrate or sodium selenite or tellurite, aluminium sulphate, and sulphuric acid; and (5) potassium permanganate, and magnesium or aluminium sulphate. MgO or Al 2 O 3 is co-deposited with the coloured oxide or hydroxide. The coloured anodized surface may be scaled by boiling water. |
