| 摘要 |
A chromating treatment composition particularly suitable for preparing aluminum and stainless steel for clear coating comprises water, anions containing hexavalent chromium, trivalent chromium cations, phosphate ions, dry process finely divided silica, and acrylic and/or methacrylic acid polymer or copolymer in such amounts that: (A) the concentration of the total of hexavalent and trivalent chromium atoms is in the range from 1 to 60 g/L; (B) the (trivalent chromium atom)/(hexavalent chromium atom) weight ratio is in the range from 0.6 to 2.5; (C) the (phosphate ion)/(total chromium atoms in hexavalent chromium ions and trivalent chromium ions) weight ratio is in the range from 0.5 to 4.5; (D) the (dry process silica)/(total chromium atoms in hexavalent chromium ions and trivalent chromium ions) weight ratio is in the range from 0.1 to 5.0; and (E) the ratio of the weight of the specified water soluble polymer in the composition to the weight of the chromium atoms in the total of the hexavalent chromium ions and trivalent chromium ions in the composition is in the range from 0.01 to 1.0. |
