| abstract |
PCT No. PCT/US92/04698 Sec. 371 Date Dec. 27, 1993 Sec. 102(e) Date Dec. 27, 1993 PCT Filed Jun. 11, 1992 PCT Pub. No. WO93/00457 PCT Pub. Date Jan. 7, 1993.The cleaned surface of an aluminum or aluminum alloy product, for example, aluminum coil, is treated with a 0.5 to 3 second spray of a chromating bath heated to 40 DEG to 60 DEG C., said bath having a pH of 1.0 to 3.0 and containing 0.1 to 3.0 g/L of tungstate ions and/or molybdate ions, 0.5 to 4.0 g/L of hexavalent chromium ions, 5.0 to 30.0 g/L of phosphate ions, and 0.05 to 2.0 g/L of free fluoride ions. A highly corrosion-resistant, highly paint-adherent chromate coating can thereby be formed on the surface of aluminum in less time than that required by prior phosphoric acid-based chromating treatments. |