| 摘要 |
1,202,879. Electro-plating with aluminium. NIPPON KOKAN K. K. Dec. 21, 1967 [Oct. 25, 1967], No.58118/67. Heading C7B. A dense adherent non-dendritic protective coated of aluminium is electro-plated onto a metal object from a fused salt bath including aluminium chloride by adding to the surface of the bath a dehydrating substance which does not react with the bath components in sufficient quantity to allow plating to occur under moisture-free conditions. The dehydrating substance may be silica gel particles, silica granules, quartz sand, minute pieces of porous ceramics, an activated clay sintered to a granular form, diatomaceous earth, charcoal, graphite, carbon black, alumina gel particles, alumina particles, glass particles, glass fibres, asbestos, or powdered anorthite, calcium sulphate, fluospar zeolite, pumice or Japanese acid clay (a mixture of acid montmorillonite clay and soluble silicic acid) or mixtures of these substances. Typically the fused salt bath consists of aluminium and sodium chlorides in a 60:40 weight ratio, with optionally some potassium chloride, and the objects coated may be of steel, iron, copper or titanium. The quantity of silica gel added to a litre of the bath (1À7 kg) is typically about 1À7 weight per cent e.g. 30g, and the aluminium content is maintained by the use of an aluminium anode. Baths containing an excess of alumina may be regenerated by passing hydrogen through them and adding dehydrating agent. |
