Low-melting-point, low-silver and cadmium-free silver brazing filler metal

Abstract

Low-melting-point, low-silver and cadmium-free silver brazing filler metal is characterized in that according to the mass percent, 11.0%-13.0% of Ag, 36.0%-43.0% of Zn, 0.01%-0.05% of Sn, 0.01%-0.05% of In, 0.01%-0.05% of Zr, 0.01%-0.05% of Sc and the balance Cu are included. A silver plate, cathode copper, a zinc ingot, a tin ingot, metal indium, a copper-zirconium alloy and metal scandium are used and added according to the component proportion. The medium-frequency smelting technology is adopted for smelting and pouring, and then a needed brazing filler metal wire is obtained through extrusion and drawing. The brazing filler metal solidus temperature is smaller than or equal to 765 DEG C, and the liquidus temperature is smaller than or equal to 795 DEG C. When commercially-sold FB102 brazing flux is matched for brazing red copper-stainless steel and red copper-brass and brass-stainless steel, the shearing strength of a brazing connector reaches the level equivalent to the contrast example (BAg45CuZn brazing filler metal) and is superior to existing BAg12CuZn (Si) brazing filler metal.

Description

technical field [0001] The invention belongs to the technical field of brazing materials of metal materials, and in particular relates to a low-melting-point, low-silver, cadmium-free silver solder. Background technique [0002] At present, there are literatures such as the BAg45CuZn solder recommended in GB / T 10046-2018 "Silver Solder". Its melting temperature range is 665°C solidus and 745°C liquidus, which is very popular among solder users in the market. Solder. However, its Ag content of 45%±1% means high “material cost” for many highly competitive industries. Reducing the Ag content in silver solder has always been the goal pursued by related manufacturing industries. [0003] As a "substitute" for BAg45CuZn solder, BAg35CuZn, BAg34CuZnSn, BAg30CuZn, BAg25CuZn solder, except that the solidus and liquidus temperature of the solder is higher than that of BAg45CuZn solder, most of the performance indicators can be "close" to BAg45CuZn solder However, the Ag content is s...

AI Technical Summary

Problems solved by technology

Since In and Li are "rare elements", the annual output in the world is also very limited. The price of In is equivalent to or higher than that of silver, and the price of Li is about 800-1000 yuan / kg, which is much higher than that of Cu (about 35-40 yuan / kg), therefore, it does not have the value of large-scale application; the price of Sn element is not high and the reserves are abundant, but when added in large quantities, it is easy to form hard and brittle intermetallic compound Cu 6 sn 5 , resulting in "difficult processing" of silver solder, except that the addition amount of Sn in BAg60CuSn solder can reach 9.5% to 10.5%, and the general addition amount in Ag-Cu-Zn-Sn series solder is 1.5% to 2.5% %, for example, the amount of Sn added in BAg56CuZnSn is 4.5% to 5.5% (see Table 1 on page 4 of GB / T 10046-2018 "Silver Solder" (continued))

[0005] However, it is not limited to the new silver solders disclosed in these documents. The main components are Ag, Cu, Zn elements (excluding phosphorus elements), and the silver solders classified as GB / T 10046-2018 have an Ag content of less than 20%. , In, Sn and other trace elements content of less than 0.15% cadmium-free silver solder, there is no wetting and spreading properties, mechanical properties of the brazing seam and other properties can be close to BAg45CuZn solder, the liquidus temperature is lower than 800 ℃ "low" "Silver solder" report

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