| 摘要 |
<p>An improved process for applying a lead-free coating by electrodeposition to an untreated ferrous metal substrate is provided. The substrate need not be phosphated prior to treatment. The process includes the following steps: a) contacting the substrate surface with a group IIIB or IVB metal compound in a medium that is essentially free of accelerators needed to form phosphate conversion coating; followed by b) electrocoating the substrate with a substantially lead-free, curable electrodepositable composition; and c) curing the electrodepositable composition. The group IIIB or IVB metal compound is preferably a zirconium compound and is typically in an aqueous medium. The process may further include initial steps of cleaning the substrate with an alkaline cleaner and rising with an acidic rince. Substrates treated by the process of the present invention demonstrate excellent corrosion resistance.</p> |
