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

• US 20030051342A1
• Filed: 07/25/2002
• Published: 03/20/2003
• Est. Priority Date: 07/30/2001
• Status: Active Grant

• Current Assignee: DENSO Corporation, Sumitomo Light Metal Industries Limited (UACJ Corporation)
• Original Assignee: DENSO Corporation, Sumitomo Light Metal Industries Limited (UACJ Corporation)
• Inventors: Nishikawa, Hiroshi, Sakai, Keiichi, Hirao, Koji, Kashima, Eiichi, Tani, Shinichi, Hasegawa, Yoshiharu, Yamashita, Naoki, Itoh, Yasunaga
• Granted Patent: US 6,849,136 B2
• Time in Patent Office: Days
• US Class Current: 29/890.03
• CPC Class Codes: B23K 35/0238 layered
• CPC Class Codes: B23K 35/286 Al as the principal constituent
• CPC Class Codes: Y10T 29/4935 Heat exchanger or boiler making

Abstract

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.

Claims

1. An Al—

Si alloy filler metal for an aluminum brazing sheet for heat exchangers which is clad on an aluminum brazing sheet and melted during heating for brazing, and which prevents or controls occurrence of a melting hole during heating for brazing, wherein the maximum particle diameter of a coarse Si particle in the filler metal is 20 μ

m or less.

2. An Al—

Si alloy filler metal for an aluminum brazing sheet for heat exchangers which is clad on an aluminum brazing sheet and melted during heating for brazing, and which prevents or controls occurrence of a melting hole during heating for brazing, wherein, provided that an average value and a standard deviation in a normal distribution of the particle diameter of a coarse Si particle in the filler metal are respectively μ and

σ

, μ

3σ

is 10 μ

m or less.

3. An Al—

Si alloy filler metal for an aluminum brazing sheet for heat exchangers which is clad on an aluminum brazing sheet and melted during heating for brazing, and which prevents or controls occurrence of a melting hole during heating for brazing, wherein the thickness of the filler metal is 30 μ

m or less, and the maximum particle diameter of a coarse Si particle in the filler metal is ⅔

or less of the thickness of the filler metal.

4. An Al—

Si alloy filler metal for an aluminum brazing sheet for heat exchangers which is clad on an aluminum brazing sheet and melted during heating for brazing, and which prevents or controls occurrence of a melting hole during heating for brazing, wherein the thickness of the filler metal is 30 μ

m or less, and, provided that an average value and a standard deviation in a normal distribution of the particle diameter of a coarse Si particle in the filler metal are respectively μ and

σ

, μ

3σ

is ⅓

or less of the thickness of the filler metal.

5. A method of manufacturing the Al—

Si alloy filler metal according to any one of claims 1 to 4, comprising adding at least one of 10-200 ppm of Na, 20-400 ppm of Sr, and 500-4000 ppm of Sb (weight ratio) to the filler metal.

6. A method of manufacturing the Al—

Si alloy filler metal according to any one of claims 1 to 4, comprising limiting the total content of impurity elements in the filler metal to less than 0.24 mass % by using a high purity ground metal.

7. A method of manufacturing the Al—

Si alloy filler metal according to any one of claims 1 to 4, comprising setting an average cooling rate from a liquidus temperature at the center of an ingot to the completion of solidification to 1°

C./s or more during the casting of the filler metal.