| 摘要 |
A concentrated aqueous solution containing: (A) a component of dissolved phosphate ions; (B) a component of dissolved hexavalent chromium; (C) a component of dissolved anions selected from the group consisting of BF4-, AlF6-3, SiF6-2, TiF6-2, FeF6-3, SnF6-2, ZrF6-2, and HfF6-2; and (D) a component of free fluoride ions; and, optionally and preferably, (E) a component of dissolved trivalent chromium; and, optionally, one or more of: (F) a component of dissolved organic substances produced by reducing some hexavalent chromium initially added to trivalent chromium; (G) a component of dissolved, stably suspended, or both dissolved and stably suspended film forming polymer molecules; and (H) a component of dissolved, stably suspended, or both dissolved and stably suspended substances selected from the group consisting of silica and silicates is more resistant to development of precipitates during extended storage than similar compositions without the free fluoride component, and upon dilution makes at least equally satisfactory working compositions for forming a chromate conversion "passivating" coating on zinciferous surfaces. |
