Method for brazing aluminum members and brazing apparatus used for same

摘要

Provided are: a method for brazing an aluminum alloy, which is characterized in that brazing is carried out by heating an aluminum brazing sheet without using flux in a furnace that is in an argon gas-containing atmosphere, said aluminum brazing sheet comprising a core material that is composed of aluminum or an aluminum alloy and a brazing filler material that is composed of an aluminum alloy and clad on one surface or both surfaces of the core material, and said core material and/or said brazing filler material containing Mg; and a brazing apparatus which is used in the method for brazing an aluminum alloy. The brazing method has good and stable brazing properties and is applicable in industrial practice.

主权项

1. A method for brazing an aluminum member, the method comprising the steps of:
placing a fluxless aluminum member into a furnace, said aluminum member comprising a brazing sheet having a two-layer structure that includes a core made of aluminum or an aluminum alloy, and a filler material made of an aluminum alloy and clad on one outer surface of said core, or having a three-layer structure that includes said filler material clad on two outer surfaces of said core, at least one of said core and said filler material containing Mg, wherein said filler material has an outer surface opposite to an inner surface thereof which is closely contacted with said core, said outer surface of said filler material being exposed to an atmosphere in said furnace and configured to melt at a lower temperature than a melting temperature of said core; heating said aluminum member in said furnace at a temperature lower than the melting temperature of said core for enabling the brazing of said aluminum member without using flux in an argon gas-containing atmosphere in a state that said outer surface of the filler material is exposed to the argon gas-containing atmosphere; and controlling the amount of argon gas introduced into the furnace such that, given that a ratio of luminous intensity of a nitrogen atom to luminous intensity of an oxygen atom, measured by glow discharge optical emission spectrometry, is defined as a luminous intensity ratio (N/O) and that the luminous intensity ratio (N/O) indicating a constant value at the interior of said filler material after having been subjected to the brazing is 1.0, the luminous intensity ratio (N/O) near the surface of said filler material up to the depth where said constant value is indicated, is 1.2 or less; wherein the argon gas-containing atmosphere in said furnace is an argon gas atmosphere or a mixed gas atmosphere of argon gas and nitrogen gas in which a volume of nitrogen gas is less than or equal to a volume of argon gas, and wherein an oxygen concentration in said furnace is 25 ppm or lower.