FLUX FOR BRAZING AND ITS PRODUCTION

摘要

PURPOSE:To obtain a flux for Al materials which forms a zinc diffusion layer having corrosion resistance in the state of brazing by consisting said flux of potassium fluorozincate of which the molar ratio of KF/ZnF2 in terms of a single compd. is within a specific range or a mixture composed thereof and zinc fluoride. CONSTITUTION:The flux consists of the potassium fluorozincate composed of the compsn. of which the molar ratio of KF/ZnF2 in terms of the single compd. corresponds to 35/65-55/45 or the mixture composed thereof and the zinc fluoride and does not contain free potassium fluoride. The method except the conventional practice to supply the flux to a brazing part consists in forming a zinc layer on the surface of the Al material, then immersing the material into an aq. soln. contg, K ion and F ion. The fluoride flux essentially consisting of the potassium fluorozincate is thereby formed on the surface of the Al material. The flux for the Al materials which can be form the corrosion-resistant zinc diffusion layer simultaneously with brazing is thus obtd.