Filler metal for aluminum brazing sheet for heat exchangers and method of manufacturing same

• Main Authors: Hasegawa, Yoshiharu, Hirao, Koji, Nishikawa, Hiroshi, Itoh, Yasunaga, Yamashita, Naoki, Tani, Shinichi, Sakai, Keiichi, Kashima, Eiichi
• Format: Patent
• Language: English
• Published: 01.02.2005

An object of the present invention is to provide a filler metal for an aluminum brazing sheet for heat exchangers capable of preventing or controlling occurrence of a melting hole during heating for brazing, and a method of manufacturing the same. In an Al-Si alloy filler metal which is clad on the aluminum brazing sheet and melted during heating for brazing, the maximum particle diameter of a coarse Si particle crystallized in the eutectic structure of the filler metal is 20 μm or less. Provided that an average value and a standard deviation in a normal distribution of the particle diameter of the coarse Si particle in the filler metal are respectively μ and σ, (μ+3σ) is preferably 10 μm or less. This brazing sheet is obtained by a method of adding a specific amount of Na, Sr, or Sb to the filler metal, a method of limiting the amount of impurities in the filler metal within a specific range, a method of specifying a cooling rate during the casting of the filler metal, or the like.