FLUX POWDER FOR BRAZING ALUMINUM MATERIAL AND PROCESS FOR PRODUCING THE FLUX POWDER

摘要

A flux powder which has satisfactory spreading properties when used in brazing magnesium-containing aluminum materials. It is noncorrosive, highly safe, relatively inexpensive, highly economical, and generally usable extensively. It is an improved flux powder for use in the brazing of aluminum materials having a magnesium content of 0.1-1.0 wt.%. It comprises KAlF₄, K₂AlF₅, and K₂AlF₅·H₂O. It is characterized in that it has composition in which the K/Al molar ratio is 1.00-1.20, the F/Al molar ratio is 3.80-4.10, and the total content of K₂AlF₅ and K₂AlF₅·H₂O is 6.0-40.0 wt.%, with the remainder being KAlF₄, and that part or all of the crystal structure of the K₂AlF₅·H₂O is at least one of K-deficient type, F-deficient type, and K- and F-deficient type crystal structures.