An aqueous silane primer has been developed to replace chromate final rinse for applications of metal-coating systems, which consists of two silane coupling agents and a silane cross-linking agent. This primer substantially enhance adhesion across metal-coating systems and may be used to 1) replace chromate final rinse in conventional phosphating processes and 2) be directly applied on a clean, metallic surface without phosphate conversion coating and chromate final rinse without largely lowering the performance in applications of metal-coating systems; in additions, extensive experimental and field tests have demonstrated that this aqueous silane primer is chemically coating-specific in the term of performance. With optimally matching, this innovative silane primer performs equivalently to or close to chromate final rinse does in metal-coating (epoxy) systems in the term of performance of corrosion resistance.

Keywords: primer, silane, chromium, adhesion, phosphate, epoxy, coating, metal