Design of Corrosion-Resistant Composites Incorporating Vitreous Enameled Metal

Vitreous enameling has long been demonstrated as one of the most useful and versatile coatings that can be applied to metal.  When the glass surface is intact, it resists corrosion even in very hostile environments.  Outdoor structures made with enameled steel, for example, routinely have greater service lifetimes compared to plated or polymer-coated steel.  Although vitreous enamel is seldom used as a structural component in composites, it is possible to take advantage of the ability of vitreous enamel to be chemically-tailored such that it provides a physically and chemically different surface allowing other structural components to be bonded to metal.  One example is the use of vitreous enamel combined with portland cement to form a layer that improves the bond between concrete and the steel reinforcement.    Research is continuing on this and other bonding phenomena that use enamel as an intermediary layer. 

New composites are being developed incorporating enameled metal with a silane coupling agent and bonded to epoxy.  In this example, a glass enamel coated metal fiber is substituted for a conventional silane-treated glass fiber and the resultant composite is a metal fiber or wire-reinforced version of a fiberglass composition.  The metal is protected from corrosion by the silane-treated glass and epoxy coating.  Potentially this can provide the fiberglass with additional strength and durability.  The glass coating on the metal avoids the problem of debonding that can occur when epoxy is applied directly to the surface of some metals.  This research indicates a family of new composites is possible since a wide variety of metals can be enameled including steel, stainless steel alloys, aluminum, and brass.