Dual powder coating for aluminum heat exchangers

Abstract

A method includes applying a first powder to an aluminum article and heating the first powder to form a first layer on the aluminum article providing mechanical strength, corrosion durability and bonding potential. The method also includes applying a second powder to the aluminum article and heating the second powder to form a second layer on the aluminum article protecting the aluminum article from ultraviolet radiation. A coated article includes an aluminum substrate, an epoxy layer and a topcoat layer. The epoxy layer promotes adhesion, enhances corrosion durability and provides mechanical strength, and is formed by applying a first powder containing an epoxy to the aluminum substrate and curing the first powder. The topcoat layer provides resistance to ultraviolet radiation and environmental contaminants, and is formed by applying a second powder to the aluminum substrate and curing the second powder.

1 - 15 . (canceled) 
     
     
         16 . A coated heat exchanger comprising:
 an aluminum substrate having first and second layers disposed thereon;   wherein the first layer is an epoxy layer having a thickness between about 15 microns and about 35 microns for promoting adhesion, enhancing corrosion durability and providing mechanical strength, formed by applying a first powder containing an epoxy to the aluminum substrate and curing the first powder; and   the second layer is a topcoat layer over the first layer, the second layer having thickness between about 15 microns and about 35 microns for providing resistance to ultraviolet radiation and environmental contaminants, formed by applying a second powder to the aluminum substrate and curing the second powder.   
     
     
         17 . The coated heat exchanger of  claim 16 , wherein the epoxy layer contains a constituent selected from the group consisting of epoxies, polyester epoxies, acrylic epoxies and fusion-bond epoxy powder coatings. 
     
     
         18 . The coated heat exchanger of  claim 16 , wherein the topcoat layer contains a constituent selected from the group consisting of acrylics, polyester-based thermoplastic polyurethanes and polyester triglycidyl isocyanurate. 
     
     
         19 . (canceled) 
     
     
         20 . The coated heat exchanger of  claim 16 , further comprising:
 a conversion coat layer between the epoxy layer and the aluminum substrate, formed by applying a conversion coating to the aluminum substrate before applying the first powder to the aluminum substrate.