S. Yoon, C. Lee, Hanyang University, Seoul, South Korea; H. Kim, RIST, Pohang, South Korea
Conventional manufacturing process of automotive brazed heat exchanger includes preparation processes before brazing such that aluminum brazing filler alloy is pre-claded on both sides of fin by extrusion method and holed aluminum tubes are coated on both sides with Zn for corrosion protection by wire arc spraying process.
This study simplified the process by kinetic spraying of all components, which consist of Al-12%Si (for the brazing filler metal), Zn (for corrosion protection), and KAlF4(flux powder). In order to observe the effect of flux on the brazing properties, four kinds of blended powder with and without flux were deposited. The bond properties and composition distribution at the braze joint area were evaluated by SEM and electron probe micro analyzer(EPMA). The resistance to corrosion is tested by the on-site field test - SWAAT(Seawater Acetic Acid Test) test.
It was observed that bonding area of brazed specimens at each side of brazing part were sounder than those of brazing products produced by a conventional method. Further, the kinetic sprayed heat exchanger showed acceptable corrosion protection and bond strength.
