| 摘要 |
PCT No. PCT/US92/11099 Sec. 371 Date Jul. 13, 1994 Sec. 102(e) Date Jul. 13, 1994 PCT Filed Dec. 31, 1992.The invention is a method for the accurate control of the conversion film thickness produced on aluminiferous metal materials by fluorine-containing acidic conversion treatment baths; and a simple method for determining the EFC value (Effective Fluorine Concentration). The EFC value is determined by potentiometric titration of a fluorine-containing acidic conversion treatment bath having pH<4 without prior pH adjustment using a fluorine ion electrode as indicator electrode. The titrant is an aqueous solution containing the Al ion, La ion, Y ion, Zr ion, Ga ion, Ce ion, or Be ion, an inflection point in the potential curve is used as an indication of the activity of the conversion treatment bath.
|
