PURPOSE: To simply remove residue of a fluoride-based flux/by successively subjecting an Al product brazed with the flux to the hydration with boiling water, etc. after providing boehmite treatment.
CONSTITUTION: Al constituent members are joined by brazing with a potassium fluoroaluminate-based flux. Since light-gray residue of the flux remains on the resulting as an ununiform film, the product is immersed in a boehmite treating soln. prepd. by adding 3% triethanol-amine to pure water at a prescribed temp. for a prescribed time and the treated product is held in a pressure vessel under a prescribed vapor pressure for a prescribed time. The residue sticking to the surface of the product becomes fine powder by decomposition and this powder is perfectly removed by washing. After anodic oxidaton treatment, the sealing treatment by hydration may be carried out in place of the boehmite treatment. The adhesion of a coating film as well as the appearance of the product is improved and the corrosion resistance of the product can also be improved because a boehmite or anodized aluminum film is formed.
NOGAMI TOYOICHIRO
KUZUU SHIGERU
