| 摘要 |
Aluminium and alloys thereof are given a hard coloured anodized coating using as electrolyte a mixture of (1) a mineral acid as conductor e.g. 0.05-4.5% H2SO4, (2) an aliphatic hydroxy acid or dicarboxylic acid, (3) a metal salt of the aliphatic acid with Cu, Fe, Ni, Co, or Mn. Aliphatic acids specified are glycollic, lactic, malic, oxalic, malonic, succinic, or maleic acid. The metal salt of these may be complexed with ammonia to improve solubility. The preferred metal salt is ferric oxalate or glycollate but oxalates of the other metals are specified. The full treatment consists of degreasing, pre-etching with NaOH and sodium gluconate, acid treatment, and then anodizing. The main anodizing stage may follow standard anodizing treatment using H2SO4. The main anodizing step is effected at 50-80 DEG F., and applying a gradually increasing voltage from 20V up to 250V. The anodizing bath may be regenerated by adding H2O2. The process may be applied to extrusions sheet or mesh aluminium. |
