| 摘要 |
PURPOSE:To improve durability of an Al-brazed joint with mixed powder for brazing composed of a non-corrosive flux for Al brazing having a specific compsn. and Al brazing filler metal powder by incorporating a specific amt. of Zn to the Al brazing filler metal. CONSTITUTION:Al-brazed joint is obtd. by coating mixed powder for brazing mixed with a non-corrosive flux for Al brazing consisting of a mixture composed of KAlF4 and K3AlF6 and consisting of 40-50wt% KF and 60-50wt% AlF3 and Al brazing filler metal powder contg. 5-12wt% Si with each other to the joint part to be Al-brazed, and heating the joint to the m.p. of the Al brazing filler metal or above. Zn is incorporated at 0.2-2wt% into the Al brazing filler metal powder in this stage. The single electrode potential of the brazing filler metal is thus made base, by which the corrosive current is suppressed or reversed and at the same time the Zn in the powdery brazing filler metal is diffused to the surface of a material for forming a passage in the stage of brazing. Generation and progression of pitting corrosion are thus suppressed and durability is improved. |
