Zn - angel or devil, part II: May the Zn be with you ...

摘要

Zn is a vital element in corrosion design of brazed heat exchangers. Over the years, the view on Zn has changed several times. On the one hand, Zn plays an important role to protect thin walled high performance extruded microtubings from corrosion. On the other hand, too high Zn amounts promote fin debonding. The paper presents and discusses the path of Zn on coated extruded tubes and its environment in the brazing furnace under several brazing conditions. The interaction of Zn with the brazing profile and the formation of protective Zn diffusion zones are discussed. A proposal for optimized Zn loads on coated extruded tubings will be presented.