Multilayer fluxless material with stepped silicon content and preparation method and application thereof

Abstract

The invention discloses a multilayer fluxless material with stepped silicon content and a preparation method and an application thereof. The multilayer fluxless material comprises a core layer, a soldering layer and a cover layer which are composited in order, and the silicon mass content of the soldering layer and cover layer are different. The cover layer and the soldering layer contains a silicon material, by using the different differential concentrations of the silicon content of the soldering layer and the cover layer, the soldering liquid flows from high density to low concentration direction, and an oxide-film is effectively broken through. at the same time, Mg with high concentration flows with the silicon material, then is diffused next to the oxide-film, under condition that oxygen content is low, the diffused magnesium and the aluminium alloy oxide-film are subjected to spinel, the generated spinel is easily coiled into the liquid by the soldering liquid (the silicon material), the soldering liquid is fully contacted, capillary and infiltration effects are employed, so that the welding quality of a soldered joint is saturated. a Bi element is added in the cover layer or the soldering layer, and the oxide-film can be firstly broken through.

Description

technical field

[0001] The invention relates to a multi-layer aluminum alloy flux-free material for heat transmission and a manufacturing process thereof. Background technique

[0002] At present, the development of the heat transfer industry requires the manufacture of high-quality materials and components with the lowest possible final cost. The most commonly used brazing production of heat exchangers is in an atmosphere of nitrogen with as few oxygen impurities as possible. This process, known as Controlled Atmosphere Brazing (“CAB”), also includes Al-K-F based fluxes, such as the Nocolok flux applied, which is achieved by adding brazing flux to decompose, dissolve and remove the oxide film to form wetting and melting. Purpose.

[0003] However, post-brazing flux residues are generally considered detrimental to heat exchangers, as they may spread on the brazed aluminum surfaces or clog internal channels, preventing efficient heat transfer with the heat exchanger. The re...

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