| 摘要 |
Protective coatings, esp., on Al, Zn or Fe strips or Zn-plated iron or steel strips, are formed under exactly the same conditions by treatment with an acid soln. contg. complex fluorides of B (pref. Ti, Zr or Fe in an amt. of 0.1-15 g/l. (calculated as metal), free fluoride ions in an amt. of 1.0-10 g/l., and an oxidising agent (pref. 0.5-30 g/l. of sodium m-nitrobenzenesulphonate). The resulting coating can be passivated with chromic and/or phosphonic acid.
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