Medium-temperature zinc-based brazing filler metal for brazing copper and steel and preparation method thereof

Abstract

The invention relates to a medium-temperature zinc-based brazing filler metal for brazing copper and steel and a preparation method thereof, which aim at providing a medium-temperature zinc-based brazing filler metal for brazing copper and steel, which has excellent comprehensive property and low cost. In the brazing filler metal, Zn is taken as a fundamental alloy component, and then elements of Sn, Cu Bi and Ni are added in the Zn to form the medium-temperature zinc-based brazing filler metal, the brazing filler metal comprises the following alloy components in mass percentage Wt%: 85-95 of Zn, 1-5 of Sn, 1-4 of Cu, 2-4 of Bi and 1-2 of Ni. The preparation method comprises the following steps that: Zn, Sn, Cu, Bi and Ni which have the purity of 99.99% and are weighed according to optimal test proportion combination are placed in a ceramic crucible; then, the crucible is placed in a well-shaped resistance furnace to be heated and melted, a thermocouple is directly inserted in the furnace body for monitoring the heating temperature; during smelting, a covering agent is added on the surface of the brazing filler metal, the smelting temperature is controlled between 500 DEG C and 550 DEG C, the heat preservation time is 10 minutes, and alloy elements are fully and uniformly mixed.

Description

technical field [0001] The invention relates to a medium-temperature zinc-based solder for brazing copper and steel and a preparation method thereof, belonging to the field of metal materials. Background technique [0002] There are hundreds of types and grades of solder, which can be divided into Sn-based, Pb-based, Zn-based, In-based, Ag-based, Ni-based, Ti-based, Al-based, and Co-based according to the content of the main elements that make up the solder. , Cu-based, Zr-based, Pd-based and Au-based, etc. Solder can be divided into soft solder and hard solder according to its melting temperature. The solder whose liquidus is lower than 450°C is called solder, and the liquidus higher than 450°C is called hard solder. [0003] The soft solder suitable for brazing copper and steel mainly includes SnPb solder and Pb-free solder. SnPb solder is to add Pb to pure Sn, and the content of Sn changes in the range of 10-90% (Wt / %, mass percentage), and at the same time, in order t...

AI Technical Summary

Problems solved by technology

[0005] In recent years, with the continuous emergence of technological innovation and high-tech products, new requirements have been put forward for brazing technology and brazing materials, especially some new functional materials are brazed with soft solder during the connection process. The working temperature cannot meet the requirements; brazing with hard solder, because its structure and properties are extremely sensitive to changes in temperature and composition, the structure and properties of the material are greatly damaged after brazing

If the brazing temperature of TiNi shape memory alloy exceeds 500 ° C, the breaking stress is reduced by more than 40%, and the superelasticity is reduced by 50%.

Die-cast copper and silver-plated copper commonly used in the instrument industry are brazed with brazing material, and blisters and peeling of the silver-plated layer will appear on the surface; the recrystallization annealing temperature of copper is about 470 ° C, and the heat effect of the joint after brazing with brazing material Softening occurs in the area, and thin parts are easily deformed by brazing

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