METAL SURFACE TREATMENT LIQUID, SURFACE TREATMENT METHOD FOR METAL BASES, AND METAL BASE OBTAINED BY SURFACE TREATMENT METHOD FOR METAL BASES

摘要

Provided is a means for further increasing corrosion resistance in comparison with conventional zirconium-based chemical conversion coating films and bismuth-based chemical conversion coating films. A metal surface treatment liquid for use in forming a composite coating film containing a Bi element and a Group 4 element on a metal base, which is a fluorine-free aqueous treatment liquid obtained by adding (A) a Bi element source, (B) a multimer of at least one Group 4 element selected from the group consisting of Zr, Ti and Hf elements, and (C) one or more aminopolycarboxylic acids or salts thereof.