Brazing flux without corrosion for aluminum and aluminum alloy brazing

Abstract

The invention relates to a corrosion-free soldering flux used for braze welding aluminium and aluminium alloy. Counted by weight percentage, the soldering flux used for braze welding the aluminium and aluminium alloy comprises the following components: 32.0-34.0 percent of cesium fluoride, 44.0-46.5 percent of aluminium fluoride, 20.5-23.5 percent of potassium fluoride, 0.5-2.5 percent of one, two or three materials selected from tin fluoride, zinc fluoride and lithium fluoride. The corrosion-free soldering flux of the invention has low melting point and better soldering performance.

Description

technical field

[0001] The invention relates to a brazing material, in particular to a non-corrosion flux for welding aluminum and aluminum alloys. Background technique

[0002] Non-corrosion fluxes used for brazing of aluminum and aluminum alloys include Nocolok flux and cesium fluoride-aluminum fluoride flux. Nocolok brazing flux has a melting point of 558°C, combined with Al-Si eutectic solder (melting point of 577°C), and an operating temperature of 600°C. It can only be used for welding pure aluminum and a few aluminum alloys such as 3003. Most aluminum alloys cannot use Nocolok flux because the overburning temperature is lower than 600°C, and the flux is not suitable for flame brazing with powdered solder. Cesium fluoride-aluminum fluoride based brazing flux, with an operating temperature of about 500°C, can braze most aluminum alloys. Because the molar ratio of cesium fluoride contained in the flux is as high as 58, its market price is expensive, so that the cesium ...