A New Chemical Process for Forming a Non-Corrosive Flux Coating for Aluminum Brazing

A new chemical process of forming a non-corrosive flux for aluminum brazing has been investigated. The flux is built up onto an aluminum surface in a layer form, which consists of K₂AlF₅·H₂O or K₂AlF₅-H₂O/Zn codeposition. The K₂AlF₅-H₂O layer formed through a chemical reaction between the aluminum metal and an aqueous treating solution gives a good adherency to the substrate and acts as the flux for brazing. The codeposition flux has an advantage of eliminating a pre-zincplating for sacrificial corrosion, since a Zn diffusion layer is formed on the aluminum surface at the brazing process.