Pretreatment compositions and methods for coating a metal substrate

摘要

Disclosed are methods for treating metal substrates, including ferrous substrates, such as cold rolled steel and electrogalvanized steel. The methods include contacting the substrate with a pretreatment composition that includes: (a) a group IIIB and/or IVB metal; (b) free fluorine; (c) a metal fluoride salt formed from a metal which forms a fluoride salt having a pKsp of at least 11; and (d) water.