A kind of copper plate and aluminum plate lap joint brazing filler metal and preparation method thereof

Abstract

The invention belongs to the field of welding materials, and relates to a strip-shaped brazing filler metal for overlapping brazing of a copper plate and an aluminum plate and a preparation method thereof. The strip-shaped solder includes solder body, coating I and coating II. The chemical composition of the solder body is: nano-zinc oxide 3.2%-4.5%, selenium 6.8%-8.2%, aluminum 2.6%-4.2%, and the balance It is zinc, coating I is composed of 90%-92% surface-modified nano-copper and the balance of polyvinyl alcohol, and coating II is composed of 90%-92% surface-modified nano-aluminum and the balance of polyvinyl alcohol , the molecular weight of polyvinyl alcohol is 8000‑12000. The melting point of the brazing filler metal of the present invention is 330°C±10°C, the brazing filler metal has good wettability, and the presence of nano-zinc oxide, nano-copper coating and nano-aluminum coating effectively improves the shear strength of the brazing joint between the copper plate and the aluminum plate , reaching above 121MPa. The invention is an innovation in the aspect of strip-shaped brazing filler metal used for overlapping brazing of copper plates and aluminum plates.

Description

technical field [0001] The invention belongs to the technical field of welding materials, and in particular relates to a strip brazing material for lap brazing of copper plates and aluminum plates and a preparation method thereof. Background technique [0002] Copper is an excellent electrical and thermal conductive material with good calendering properties, and is widely used in power transmission, heat exchange, electronic products, refrigeration equipment and other fields. However, copper is a scarce metal and belongs to a strategic resource. In recent years, copper prices have remained high, limiting the application of copper. The resource shortage of copper and the resulting rise in copper prices have prompted scientific and technological workers to start looking for substitutes for copper. Aluminum has excellent electrical and thermal conductivity, corrosion resistance and good processability, and is the best material to replace copper. Due to the difference in certai...

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Problems solved by technology

[0004] Chinese patent CN103317253B (application date is June 3, 2013) discloses a Zn-Al-Cu based solder for aluminum / copper brazing and its preparation method, which has high shear strength and good corrosion resistance , but using 5%-16% aluminum, the melting point of the solder obtained is 370°C-410°C, and the temperature is relatively high, which cannot fully meet the application of copper-aluminum brazing, and the excessive aluminum content and copper content cause brazing Cu 3 Al 2 and CuAl 2 The intermetallic compound weakens the shear strength of the brazed joint, and the summary of the invention and the examples do not give the experimental data of the shear strength

[0006] At present, the technical problems in this field are: the melting temperature of the solder is relatively high, resulting in poor wettability during brazing, and poor brazing processability; the shear strength of copper-aluminum joints is low

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