Composite board and preparation method thereof

Abstract

The invention discloses a composite board and a preparation method thereof. The method comprises the following steps: preparing a core material cast ingot, a filling layer alloy plate and a covering layer alloy plate; hot-rolling the composite core material cast ingot and the filling layer alloy plate to obtain an alloy coiled material; and cold-rolling the composite coating alloy plate and the alloy coiled material. The composite board comprises a core material, a filling layer and a covering layer which are stacked in sequence, the covering layer is prepared from the following aluminum alloycomponents in percentage by weight: 5.0 to 12.6 percent of Si, less than or equal to 0.8 percent of Fe, less than or equal to 0.25 percent of Cu, less than or equal to 0.1 percent of Mn, less than orequal to 0.1 percent of Zn, 0.05 to 0.2 percent of Bi, less than or equal to 0.1 percent of Sr, less than or equal to 0.1 percent of Eu and less than or equal to 0.1 percent of Yb; the filling layeraluminum alloy comprises the following components in percentage by weight: 7.0-15.0% of Si, less than or equal to 0.8% of Fe, less than or equal to 0.3% of Cu, less than or equal to 0.15% of Mn, lessthan or equal to 0.15% of Zn, 0.05-0.5% of Mg, 0.05-0.2% of Bi, less than or equal to 0.1% of Sr and less than or equal to 0.1% of Gd; the core material is one of series 1, series 3, series 5, series6, and series 7 aluminum alloys. The composite board is used as a soldering flux-free brazing material for the finned tube in the automobile condenser, and the welding rate reaches up to 95% or above.

Description

technical field [0001] The invention discloses a composite plate and a preparation method thereof, belonging to the technical field of brazing aluminum alloy manufacturing industry. Background technique [0002] The brazing methods used by automotive heat exchanger manufacturers are mainly divided into two categories: vacuum brazing (VB) and controlled atmosphere brazing (CAB). [0003] Vacuum brazing relies on the evaporation of Mg in the solder to destroy the oxide film on the aluminum surface, and at the same time, the degassing effect of Mg itself makes the workpiece no longer oxidize when heated and promotes the wettability of the molten solder. The advantages of the vacuum method are: ① No flux is required, no harmful gas will be produced during heating, no cleaning after welding, and no environmental pollution; ② No flux residues and corrosion problems caused by salt, and the product has a long service life; ③ Surface after welding Bright, good appearance effect. Ho...

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Problems solved by technology

However, there are some disadvantages: ① Flux is not soluble in water, so the coating of flux is troublesome, and it is necessary to dry the coated flux products; ② Fluoride flux will react with Mg, which will affect the There are strict requirements on the Mg content of brazing flux, which should generally be controlled below 0.5%, which limits the application of Mg-containing aluminum alloys such as 5xxx and 6xxx series; ③The operating temperature of the flux is high (higher than 570°C), s

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