| abstract |
This invention is a blended powder mixture including a thermosetting resin and a solid, non-hydrolyzed, functional low molecular weight organosilane coupling agent. The powder mixture may be used to form a composite coating to protect a steel substrate from corrosion. The composite coating is formed by coating the substrate with an inorganic layer such as a silicate, depositing the powder mixture over the inorganic layer, heating the substrate to a temperature at least equal to the curing temperature of the resin and maintaining the substrate at the curing temperature for sufficient time to crosslink the resin and to diffuse the organosilane to the substrate whereby the crosslinked layer is coupled to the inorganic layer by the organosilane. The powder mixture includes 0.01-10 wt. % organosilane having a melting point no greater than the curing temperature of the resin. Preferred thermosetting resins include epoxy, polyester, epoxy-polyester, acrylic, acrylic-urethane or fluorovinyl. |