CN110625288B

CN110625288B - Ga and Nd-containing low-silver cadmium-free silver solder

Info

Publication number: CN110625288B
Application number: CN201910796107.4A
Authority: CN
Inventors: 薛鹏; 王克鸿; 周琦; 龙伟民; 钟素娟
Original assignee: Nanjing University of Science and Technology
Current assignee: Nanjing University of Science and Technology
Priority date: 2019-08-27
Filing date: 2019-08-27
Publication date: 2021-06-29
Anticipated expiration: 2039-08-27
Also published as: CN110625288A

Abstract

The invention discloses a low-silver cadmium-free silver solder containing Ga and Nd. The silver solder comprises the following components in percentage by mass: 15.5 to 16.5 percent of Ag15, 39 to 41 percent of Cu, 0.3 to 0.5 percent of Ga0.03 to 0.05 percent of Nd0.003 to 0.008 percent of Zr0.0003 to 0.0008 percent of Be0.0008 percent of Zn, and the balance of Zn, wherein the trace alloy elements Ga: Nd: 1: 10 and Zr: Be: 1: 10. The low-silver cadmium-free silver solder containing Ga and Nd can replace solders such as BAg20CuZnCd, BAg25CuZn and the like, has the characteristics of good fluidity, good wettability, high strength of welding spots, excellent plasticity and the like, can be conveniently rolled into soldering lugs and can be prepared into sectional materials such as welding rings and the like, particularly can be conveniently prepared into filaments with the diameter of 0.5-1.2 mm, and is suitable for soldering of lamp decorations and bathroom products.

Description

Ga and Nd-containing low-silver cadmium-free silver solder

Technical Field

The invention belongs to the technical field of brazing materials, and relates to a low-silver cadmium-free silver brazing filler metal containing Ga and Nd.

Background

In the BAg20CuZnCd and BAg25CuZn solders used in the prior art, because the chemical components of the BAg20CuZnCd contain Cd elements, the content of Ag in the BAg25CuZn solders is higher, and the brazing performance is excellent when a soldering flux (such as FB102 soldering flux) is matched, but the requirement of market competition of hardware products (particularly lamp decorations and bathroom products) in the household appliance industry cannot be met. Therefore, the silver solder with about 16% of silver content, moderate melting point and excellent plasticity is urgently needed to be developed, and the production cost is reduced while the high-quality connection of products is ensured.

Although the published chinese patent literature contains technical information of low-silver and cadmium-free silver solder, there are a few examples of the multi-alloy cadmium-free low-silver solder disclosed in CN101716702A, the application of a low-silver solder provided in CN101347871 in the end ring and lead bar soldering process of a motor rotor, the cadmium-free low-silver solder disclosed in CN102416530A, and the preparation method thereof. However, the silver contents of the low-silver cadmium-free silver solders disclosed in the prior documents are all 16.0-40.0%, and more specifically, the low-silver cadmium-free silver solders or the BAg25CuZn solders which have the silver content of about 16% and the melting point of the solder close to BAg20CuZnCd are not included. CN201611157535.5 discloses a low-cadmium silver solder, the Ag content is reduced to 13.5% -16.0%, but it contains 0.05% -0.13% Cd, and is not suitable for soldering products which are in close contact with human body, such as lamp decoration and bathroom products. Therefore, the existing silver solder can not replace BAg20CuZnCd or BAg25CuZn solder in the manufacturing of products such as sanitary ware and lamp decoration which are closely related to the life of people under the condition of not changing the existing production process.

Disclosure of Invention

The invention provides a low-silver cadmium-free silver solder containing Ga and Nd, which is equivalent to the wetting property and the melting point close to the wetting property of BAg20CuZnCd or BAg25CuZn solder and can meet the soldering requirements of products such as sanitary ware, lamp decorations and the like.

The technical scheme of the invention is as follows:

a low-silver cadmium-free silver solder containing Ga and Nd comprises the following components in percentage by mass: 15.5 to 16.5 percent of Ag15, 39 to 41 percent of Cu, 0.3 to 0.5 percent of Ga0.03 to 0.05 percent of Nd0.003 to 0.008 percent of Zr0.0003 to 0.0008 percent of Be0.0008 percent of Zn, and the balance of Zn, wherein the trace alloy elements Ga: Nd: 1: 10 and Zr: Be: 1: 10.

The raw materials of the Ga-Nd-containing low-silver cadmium-free silver solder are commercially available silver ingots, cathode copper, zinc ingots, metal gallium, metal neodymium, beryllium copper and zirconium copper alloy which meet the national standard, the raw materials are proportioned according to the requirement, smelted and cast by a conventional intermediate frequency smelting furnace, and then the required solder wire material is obtained by extrusion and drawing. The low-silver cadmium-free silver solder containing Ga and Nd can replace the solder of BAg20CuZnCd or BAg25CuZn and the like, has the characteristics of good fluidity, good wettability, high strength of welding spots, excellent plasticity and the like, can be conveniently rolled into soldering lugs and can be prepared into sectional materials of welding rings and the like, and particularly can be conveniently prepared into filaments with the diameter of 0.5-1.2 mm so as to be suitable for soldering of lamp decorations and sanitary ware products.

Compared with the BAg20CuZnCd or BAg25CuZn solder in the prior art, the invention not only has the characteristics of good fluidity, good wettability, high strength of welding spots, excellent plasticity (being beneficial to processing into filaments with the diameter of 0.5-1.2 mm) and the like, but also has the melting temperature range close to that of the BAg20CuZnCd or BAg25CuZn solder, thereby avoiding the problems of workpiece oxidation, soldered joint strength reduction and the like caused by overhigh soldering temperature, and being particularly suitable for soldering products such as sanitary ware, lamp decoration and the like.

Detailed Description

The technical scheme of the invention mainly solves the following two key technical problems: 1) the low-silver cadmium-free silver solder containing Ga and Nd has the characteristics of good fluidity, high welding spot strength, excellent plasticity and the like, can be conveniently rolled into a soldering lug and a welding ring and other profiles, and particularly can be conveniently prepared into a filament with the diameter of 0.5-1.2 mm so as to be suitable for soldering of lamp decorations and sanitary ware products; 2) by adding proper amount of Ga, Nd, Zr and Be elements into the low-silver cadmium-free silver solder containing Ga and Nd, and simultaneously by optimizing combination of the content of the elements and optimizing and adjusting the proportion, the silver solder has excellent wettability on red copper, brass, nickel-based alloy, steel and stainless steel, and has a lower melting temperature close to that of BAg20CuZnCd or BAg25CuZn solder, so the silver solder is particularly suitable for soldering products such as sanitary ware, lamp decorations and the like.

In the production process, commercially available silver ingots, cathode copper, zinc ingots, metal gallium, metal neodymium, beryllium copper and zirconium copper alloy which meet the national standard are used, are proportioned according to the requirement, smelted and cast by a conventional intermediate frequency smelting furnace, and then extruded and drawn to obtain the required brazing filler metal wire. Compared with the prior art, the process basically does not increase the equipment investment, so the production cost is not increased, and the market competitiveness of the brazing filler metal is improved.

Compared with the prior research, the technical scheme of the invention has the creativity that:

1. researches find the synergistic effect of trace Zr and Be elements.

In the beryllium bronze with the serial number of 19-25 in Table 3 (continuation) of GB/T5231-2001 processing copper and copper alloy chemical compositions and product shapes, the addition amount of beryllium (Be) is 0.2-2.1%. The Baidu search for "beryllium bronze" gives the introduction of "first paragraph" as: "a tin-free bronze with beryllium as the main alloy component. Contains 1.7 to 2.5 percent of beryllium and a small amount of elements such as nickel, chromium, titanium and the like, and after quenching and aging treatment, the strength limit can reach 1250 to 1500MPa, which is close to the level of medium-strength steel. Has good plasticity in a quenching state and can be processed into various semi-finished products. Beryllium bronze has high hardness, elastic limit, fatigue limit and wear resistance, and also has good corrosion resistance, thermal conductivity and electrical conductivity, does not generate sparks when impacted, and is widely used as important elastic elements, wear-resistant parts, explosion-proof tools and the like. Commonly used brands are QBe2, QBe2.5, QBe1.7, QBe1.9, etc.

Similarly, GB/T5231-2001 chemical composition and product shape for processing copper and copper alloy, Table 3 (continuation) shows zirconium bronzes with a number of 32-33, wherein the amount of added zirconium (Zr) is 0.15% -0.5%. The 'zirconium bronze' is searched by adopting Baidu search, and the 'first-stage' introduction given is as follows: "a special bronze with zirconium as main alloying element. Small amounts of zirconium are sometimes added to improve strength. Common designations are qzr0.2 and qzr0.4. Has good heat resistance and creep resistance, and has better plasticity and conductivity at high temperature. And (3) preparing by a melting method. The alloy is mainly used as resistance welding parts, high-strength electrode materials and the like. Zirconium bronze is widely used in the matching parts of main equipment for smelting and rolling in the steel industry because of its high electrical and thermal conductivity and easy processing.

As a brazing material, on the materials needing brazing (the invention mainly aims at red copper, brass, nickel-based alloy, steel and stainless steel), the brazing material has the advantages of good fluidity, good wettability, high strength of welding spots and excellent plasticity of the brazing filler metal, namely, the basic requirement of brazing is met. In addition, the melting temperature range of the brazing filler metal is one of the important technical indexes. Obviously, the silver solder using Ag-Cu-Zn as a base alloy does not need to have the strength limit and the elasticity limit of 1250-1500 MPa like beryllium bronze, and does not need to have the good heat strength like beryllium bronze. In contrast, silver solder is required to have appropriate physical and mechanical properties at the lowest possible solidus and liquidus temperatures.

Tests show that in the silver solder with the Ag15.5-16.5%, when multiple trace alloy elements coexist, the mechanical property of the silver solder can be obviously improved by extremely trace Zr element. In order to match the mechanical properties of the silver solder with the application requirements, the addition amount of Zr element should be as small as possible, and is optimally controlled within the range of 0.003-0.008%. The effect of the Be element is more remarkable than that of the Zr element, and tests show that the addition amount of the Be element in the silver solder can Be controlled to Be several ppm to achieve the effect of more beneficial and less harmful effects. The optimized result is that the adding amount is controlled to be0.0003% -0.0008%. When Zr: Be is 1: 10, the brazing filler metal has the best welding spot strength and excellent brazing filler metal plasticity. The brazing connection points of the products of the lamp decoration and the sanitary ware are complex and fine, a fine brazing filler metal wire is needed, and the brazing filler metal with excellent plasticity is beneficial to being processed into a thin wire with the diameter of 0.5-1.2 mm.

2. Researches find out the influence rule of trace Ga and Nd on the melting temperature, the wetting property and the flowing property of the low-silver solder.

In Ag-Cu-Zn solder in the latest effective version GB/T10046-2018 silver solder in the table 1 (continuation), the BAg45CuZn solder has the lowest melting temperature range, the solidus temperature is 645 ℃, and the liquidus temperature is 745 ℃; in the Ag-Cu-Zn-Sn solder, the solidus temperature of BAg56CuZnSn solder is 620 ℃, and the liquidus temperature is 655 ℃; the solidus temperature of BAg60CuSn solder is 600 ℃, and the liquidus temperature is 730 ℃. As can be seen, in the cadmium-free silver solder, the solidus temperature and the liquidus temperature of the silver solder are not lower as the Ag content is higher. The solidus line and liquidus line temperatures of the silver solder are related to the influencing factors of the phase diagram of Ag-Cu-Zn or Ag-Cu-Zn-Sn alloy, namely the physical properties, metallurgical behaviors and chemical reactions of elements and alloys thereof, and the influencing factors are very complex. The invention aims to develop a silver solder with Ag content of 15.5-16.5%, which has proper physical and mechanical properties and meets the brazing requirements of products such as sanitary ware, lamp decorations and the like on the premise of keeping the solidus and liquidus temperatures as low as possible.

The existing research shows that the Ga element can obviously reduce the melting temperature of the silver solder. A large number of test results show that the addition amount of Ga element in the low-silver cadmium-free silver solder is less than or equal to 4 percent, the influence on the melting temperature of the low-silver cadmium-free silver solder is in a linear decreasing relation, and the physical and mechanical properties of the solder are not negatively influenced.

However, as Ga belongs to rare and precious metals, the price of Ga is equivalent to or slightly higher than that of Ag, the addition of Ga is excessive, the cost of the brazing filler metal is increased, and the silver reduction effect is not obvious. In addition, the silver solder with higher Ga content (1-4%) has poorer wettability to brass-brass and brass-steel than BAg20CuZnCd or BAg25CuZn solder. Therefore, if the cost of raw materials is not obviously reduced and the wettability of the brazing filler metal is deteriorated, the significance of researching and developing a new brazing filler metal is lost; however, if the amount of Ga added is too small, the melting temperature of the solder is not significantly lowered. The problem of how to solve the problem that the wettability of the silver solder added with Ga to brass-brass and brass-steel is worse than that of BAg20CuZnCd or BAg25CuZn solder is also solved by the invention.

Researches find that the addition of a pure metal rare earth element Nd can generate a synergistic effect with Ga, the melting temperature of the low-silver cadmium-free silver solder is reduced, and the problem of poor wettability of the Ga-containing silver solder in the process of brazing brass, steel and brass-304 stainless steel is obviously improved, and meanwhile, the low-silver cadmium-free silver solder containing Ga and Nd has excellent fluidity (namely permeability) in the process of brazing, and can smoothly fill brazing gaps. The intensive research finds that the addition amounts of Ga and Nd are different from the Ga-Nd synergistic effect reported in the literature, in the technical scheme, the addition amount of Ga should be controlled within the range of 0.3-0.5%, the addition amount of Nd should be controlled within the range of 0.03-0.05%, and Ga: Nd is 1: 10, so that the additive has the best performance, namely, excellent economical efficiency, and excellent wettability and fluidity.

Specific examples of the low-silver and cadmium-free silver solder containing Ga and Nd according to the present invention, which exhibit the above-described technical effects, are as follows.

Example 1

15.5 percent of Ag15, 78 percent of Cu41 percent, 0.3 percent of Ga0, 0.03 percent of Nd0.008 percent of Zr0, 0.0008 percent of Be0, and the balance of Zn. Wherein Ga: Nd: 1: 10, Zr: Be: 1: 10.

The solidus temperature of the Ga-Nd containing low-silver cadmium-free silver solder obtained by the component ratio is 665 +/-10 ℃, and the liquidus temperature is 760 +/-10 ℃ (both the measurement errors are considered). The solidus temperature is slightly above 605 ℃ for BAg20CuZnCd, but below 700 ℃ for BAg25 CuZn. The liquidus temperature is comparable to 765 ℃ for BAg20CuZnCd, but significantly lower than 790 ℃ for BAg25CuZn (see GB/T10046-. The brazing filler metal has good fluidity during brazing, and has excellent wettability to base metals such as red copper, brass (particularly, HPb58-2, HPb58-3, and HPb57-4 brass), nickel-based alloys, steels (e.g., Q235 and Q345 steels), 304 stainless steels, and the like.

By using a flame brazing mode and matching FB102 brazing flux, the brazing seam strength of the brazing base metal is shown in data in brackets when the brazing base metal is combined as follows: red copper-brass (HPb58-3 brass, same below) (sigma)_b220 + -25 MPa, tau 210 + -30 MPa), red copper-nickel base alloy (sigma)_b230 ± 25MPa, τ 210 ± 30MPa), brass-nickel based alloys (σ)_b340 ± 25MPa, τ 335 ± 30MPa), Q235 steel-304 stainless steel (σ 235 steel-304 stainless steel_b360 +/-25 MPa, and tau 355 +/-30 MPa), is superior to the mechanical property data of soldered joints when the BAg20CuZnCd solder is matched with a soldering flux (such as FB102 soldering flux) for soldering red copper-brass, red copper-nickel base alloy, brass-nickel base alloy and Q235 steel-304 stainless steel.

Example 2

Ag16.5%, Cu39%, Ga0.5%, Nd0.05%, Zr0.003%, Be0.0003%, and the balance of Zn. Wherein Ga: Nd: 1: 10, Zr: Be: 1: 10.

The solidus temperature of the Ga-Nd containing low-silver cadmium-free silver solder obtained by the component ratio is 665 +/-10 ℃, and the liquidus temperature is 760 +/-10 ℃ (both the measurement errors are considered). The solidus temperature is slightly higher than 605 ℃ of BAg20CuZnCd, but lower than 700 ℃ of BAg25 CuZn; the liquidus temperature is comparable to 765 ℃ for BAg20CuZnCd, but significantly lower than 790 ℃ for BAg25CuZn (see GB/T10046-. The brazing filler metal has good fluidity during brazing, and has excellent wettability to base metals such as red copper, brass (particularly, HPb58-2, HPb58-3, and HPb57-4 brass), nickel-based alloys, steels (e.g., Q235 and Q345 steels), 304 stainless steels, and the like.

By using a flame brazing mode and matching FB102 brazing flux, the brazing seam strength of the brazing base metal is shown in data in brackets when the brazing base metal is combined as follows: red copper-brass (HPb58-3 brass, same below) (sigma)_b220 + -25 MPa, tau 210 + -30 MPa), red copper-nickel base alloy (sigma)_b230 ± 25MPa, τ 210 ± 30MPa), brass-nickel based alloys (σ)_b340 ± 25MPa, τ 335 ± 30MPa), Q235 steel-304 stainless steel (σ 235 steel-304 stainless steel_b360. + -. 25MPa, and. tau. 355. + -. 30MPa), preferablyAnd (3) brazing mechanical property data of brazed joints when the BAg20CuZnCd brazing filler metal is matched with a scaling powder (such as FB102 brazing flux) for brazing red copper-brass, red copper-nickel base alloy, brass-nickel base alloy and Q235 steel-304 stainless steel.

Example 3

Ag16.0%, Cu 40%, Ga0.4%, Nd0.04%, Zr0.005%, Be0.0005%, and the balance Zn. Wherein the trace alloy elements Ga: Nd: 1: 10 and Zr: Be: 1: 10.

Example 4

15.8 percent of Ag15, 39.5 percent of Cu39, 0.35 percent of Ga0, 0.035 percent of Nd0.006 percent of Zr0, 0.0006 percent of Be0, and the balance of Zn. Wherein the trace alloy elements Ga: Nd: 1: 10 and Zr: Be: 1: 10.

Example 5:

ag16.2%, Cu40.2%, Ga0.45%, Nd0.045%, Zr0.007%, Be0.0007% and the balance of Zn. Wherein the trace alloy elements Ga: Nd: 1: 10 and Zr: Be: 1: 10.

By using a flame brazing mode and matching FB102 brazing flux, the brazing seam strength of the brazing base metal is shown in data in brackets when the brazing base metal is combined as follows: red copperBrass (HPb58-3 Brass, same below) (σ)_b220 + -25 MPa, tau 210 + -30 MPa), red copper-nickel base alloy (sigma)_b230 ± 25MPa, τ 210 ± 30MPa), brass-nickel based alloys (σ)_b340 ± 25MPa, τ 335 ± 30MPa), Q235 steel-304 stainless steel (σ 235 steel-304 stainless steel_b360 +/-25 MPa, and tau 355 +/-30 MPa), is superior to the mechanical property data of soldered joints when the BAg20CuZnCd solder is matched with a soldering flux (such as FB102 soldering flux) for soldering red copper-brass, red copper-nickel base alloy, brass-nickel base alloy and Q235 steel-304 stainless steel.

Comparative example 1

Ag16.0%, Cu 40%, Ga0.4%, Nd0.05%, Zr0.005%, Be0.0005%, and the balance Zn. Wherein the trace alloy elements Ga: Nd: 1: 8 and Zr: Be: 1: 10.

The solidus temperature of the low-silver cadmium-free silver solder containing Ga and Nd obtained by the component proportioning is 670 +/-10 ℃, and the liquidus temperature is 770 +/-10 ℃ (both the measurement errors are considered). The solidus temperature is higher than 605 ℃ of BAg20CuZnCd, but lower than 700 ℃ of BAg25 CuZn; the liquidus temperature is comparable to 765 ℃ for BAg20CuZnCd, but less than 790 ℃ for BAg25CuZn (see GB/T10046-. The brazing filler metal has good fluidity during brazing, and has good wettability to base materials such as red copper, brass (particularly, HPb58-2, HPb58-3, and HPb57-4 brass), nickel-based alloys, steels (e.g., Q235 and Q345 steels), 304 stainless steels, and the like.

By using a flame brazing mode and matching FB102 brazing flux, the brazing seam strength of the brazing base metal is shown in data in brackets when the brazing base metal is combined as follows: red copper-brass (HPb58-3 brass, same below) (sigma)_b210 ± 25MPa, τ 205 ± 30MPa), red copper-nickel base alloy (σ)_b220 + -25 MPa, tau 200 + -30 MPa), brass-nickel base alloy (sigma)_b330 ± 25MPa, τ 330 ± 30MPa), Q235 steel-304 stainless steel (σ)_b350 +/-25 MPa and tau 345 +/-30 MPa), and has similar mechanical performance data of soldered joints when being used for soldering red copper-brass, red copper-nickel base alloy, brass-nickel base alloy and Q235 steel-304 stainless steel with the BAg20CuZnCd soldering flux (such as FB102 soldering flux), but lower than the results of the examples 1 to 5.

Comparative example 2

Ag16.0%, Cu 40%, Ga0.4%, Nd0.04%, Zr0.004%, Be0.0005%, and the balance of Zn. Wherein the trace alloy elements Ga: Nd: 1: 10 and Zr: Be: 1: 8.

Comparative example 3

Ag16.0%, Cu 40%, Ga0.4%, Nd0.05%, Zr0.004%, Be0.0005%, and the balance of Zn. Wherein the trace alloy elements Ga: Nd: 1: 8 and Zr: Be: 1: 8.

From the test results of comparative examples 1 to 3, it can Be seen that the addition amounts of trace elements Ga, Nd, Zr, and Be and the ratios of the elements have significant effects on the physical properties and brazing seam mechanical properties of the solder, which indicates that the synergistic effect of Zr and Be and the synergistic effect of rare earth elements Nd and Ga are significant, and particularly, the performance of the solder is optimal when the proportional relationship of Ga: Nd ═ 1: 10 and Zr: Be ═ 1: 10 is ensured.

Comparative example 4

Ag16.0%, Cu 40%, Ga0.4%, Zr0.005%, Be0.0005%, and the balance Zn. Wherein the trace alloy element Zr: Be: 1: 10.

The solidus temperature of the Nd-free low-silver cadmium-free silver solder prepared by the components is 675 +/-10 ℃, and the liquidus temperature is 765 +/-10 ℃ (both considering the measurement error). The solidus temperature is higher than 605 ℃ of BAg20CuZnCd, but lower than 700 ℃ of BAg25 CuZn; the liquidus temperature is comparable to 765 ℃ for BAg20CuZnCd, but less than 790 ℃ for BAg25CuZn (see GB/T10046-. The solder has a good fluidity during soldering, and has good wettability to base materials such as copper, brass (particularly, HPb58-2, HPb58-3, and HPb57-4 brass), nickel-based alloys, steels (e.g., Q235 and Q345 steels), and 304 stainless steels.

By using a flame brazing mode and matching FB102 brazing flux, the brazing seam strength of the brazing base metal is shown in data in brackets when the brazing base metal is combined as follows: red copper-brass (HPb58-3 brass, same below) (sigma)_b190 + -25 MPa, tau 185 + -30 MPa), red copper-nickel base alloy (sigma)_b220 + -25 MPa, tau 200 + -30 MPa), brass-nickel base alloy (sigma)_b300 ± 25MPa, τ 310 ± 30MPa), Q235 steel-304 stainless steel (σ)_b＝350±25MPa，τ＝345±30MPa)。

As can be seen from the data, the solder without Nd has poor wetting and spreading performance with brass, and when the solder is used for soldering red copper-brass and copper-nickel base alloy by matching with a soldering flux (such as FB102 soldering flux), the mechanical performance data of the soldered joint is obviously lower than that of the solder in examples 1 to 5; the mechanical property data of the brazed joint when the red copper-nickel base alloy and the yellow Q235 steel-304 stainless steel are brazed are similar, but still lower than the results of the examples 1 to 5. The test result not only verifies the characteristics of good wettability of the Ga-containing silver solder to red copper but poor wettability to brass, but also verifies the existence of Ga-Nd synergistic effect, and can improve and enhance the surface tension of the Ga-containing silver solder, so that the Ga-containing silver solder has the same excellent wetting and spreading properties to brass and red copper.

Comparative example 5

Ag16.0%, Cu 40%, Ga0.5%, Nd0.05%, Zr0.004%, and the balance of Zn. Wherein the trace alloy elements Ga: Nd: 1: 10.

By using a flame brazing mode and matching FB102 brazing flux, the brazing seam strength of the brazing base metal is shown in data in brackets when the brazing base metal is combined as follows: red copper-brass (HPb58-3 brass, same below) (sigma)_b200 + -25 MPa, tau 190 + -30 MPa), red copper-nickel base alloy (sigma)_b210 ± 25MPa, τ 190 ± 30MPa), brass-nickel based alloy (σ)_b320 ± 25MPa, τ 315 ± 30MPa), Q235 steel-304 stainless steel (σ)_b＝340±25MPa，τ＝335±30MPa)。

As can Be seen from the above data, the mechanical properties of the brazed joints when the Be-free brazing filler metal is used with a brazing flux (such as FB102 flux) to braze red copper-brass, red copper-nickel based alloy, brass-nickel based alloy, and Q235 steel-304 stainless steel are significantly lower than those of the brazed joints of examples 1-5.

In addition, the silver solder without Be is easy to generate wire breakage phenomenon in the preparation process of the filament solder, the plasticity of the silver solder is obviously reduced, the wire breakage phenomenon is very serious when the diameter of the solder wire is less than 0.8mm, and the silver solder is hardly drawn into a0.5 mm filament when the diameter of the solder wire is less than 0.6 mm.

Claims

1. The low-silver cadmium-free silver solder containing Ga and Nd is characterized by comprising the following components in percentage by mass: 15.5-16.5% of Ag15, 39-41% of Cu, 0.3-0.5% of Ga0.03-0.05% of Nd0.003-0.008% of Zr0.0003-0.0008% of Be0.0008% of and the balance of Zn, wherein the trace alloy elements Ga: Nd = 10: 1 and Zr: Be = 10: 1.