THE STUDY OF THE INFLUENCE OF ZNCL2 CONTENT IN A FLUX FOR BRAZING OF AL-MG ALLOYS ON ITS TECHNOLOGICAL PROPERTIES

Aluminum-magnesium alloys are ductile alloys with good weldability, corrosion resistance, and a high fatigue strength level. Aluminum-magnesium alloys contain up to 6 % magnesium. The higher its content, the stronger is the alloy. However, these alloys with high magnesium content are difficult to solder. Therefore, the task is to create flux compositions for high-temperature brazing of these alloys providing high-quality brazed joints. The work investigated the influence of the ZnCl₂ activator on the technological properties of the flux. The authors tested the flux compositions with ZnCl₂ content of 0 to 12 %. The tests were carried out on the AMg2 alloy using the AK12 solder. The authors evaluated the influence of ZnCl₂ content on the spreading area of solder, the spreading uniformity, and the surface condition. The study revealed a significant increase in the spreading area of solder when introducing the ZnCl₂ activator into the flux and the introduction of 4 % zinc chloride made it possible to increase the spreading zone of a solder drop by 50-55 %. The authors considered the samples brazed with a flux that did not contain ZnCl₂ and using flux with the addition of 4 % ZnCl₂. Activator content in the flux increased by 4 % before reaching 12 %. The study identified the strong interaction between the flux and the base metal with the release of gaseous products leading to the pore formation. As a result of the work, it was revealed that ZnCl₂ significantly affects the flux properties, allowing increasing the solder spreading area; however, in the result of reactions with the formation of gaseous products, it can lead to the porosity of the brazed joint.

flux, zinc chloride, activator, brazing, oxidation film destruction, aluminum-magnesium alloys