Silver solder and its preparation method

Abstract

The present invention relates to silver solder and a method for preparing the same. [Solution] The silver solder can take the form of a foil-like silver solder containing several nickel layers, or a wire-like silver solder containing several nickel cores. The foil-like silver solder contains several nickel layers and several silver alloy layers, with the nickel layers and silver alloy layers arranged alternately, and the outermost layer being the silver alloy layer. The wire-like silver solder contains several nickel cores and a silver alloy portion that surrounds the nickel cores on the outside. Multiple nickel layers or multiple nickel cores are fixed at intervals within the cavity of a mold, the remaining molten solder metal is poured in, and the mold is demolded to obtain a multi-layered plate-like or columnar ingot having multiple nickel cores. A foil-like silver solder or wire-like silver solder with a high nickel content can then be obtained by a general processing method.

Description

[Technical Field]

[0001] This invention belongs to the technical field of brazing materials, and more specifically, to a method for preparing silver solder and the same. [Background technology]

[0002] Silver solder is currently the most widely used hard soldering material, offering excellent process performance, a suitable melting point, good wetting and gap-filling capabilities, superior strength of the solder material and brazed joints, and excellent conductivity and corrosion resistance. For these reasons, silver solder is widely used for brazing multiphase alloy components such as hard alloy tools and diamond tools. As the operating environments for hard alloy tools and diamond tools become more extreme and complex, the demands on the overall performance of silver solder are increasing, making the research and development of high-performance silver solder an urgent necessity.

[0003] Nickel is a performance-enhancing element commonly used in silver solder. Adding just 2% nickel by mass significantly increases the strength of the solder and the brazed joint. To substantially improve the mechanical properties of silver solder, the nickel content needs to be increased to 15% or more. However, at a nickel content of 2.5%, the hardness and brittleness of the solder increases sharply, greatly degrading its workability, making it difficult to obtain high-nickel, high-performance silver solder.

[0004] Furthermore, conventional silver solder has a low level of cleanliness, which makes it prone to defects such as slag and pores in the brazed structure. This results in a low brazing rate, causing the multiphase alloy component to lose its function prematurely during use and shortening the service life of the component.

[0005] To address the aforementioned shortcomings, there is an urgent need to develop a high-performance silver solder suitable for highly reliable brazing of multiphase alloy components, possessing high cleanliness, high brazing strength, and a high nickel content.

[0006] In view of this, the present invention is provided. [Overview of the project] [Problems that the invention aims to solve]

[0007] The first objective of the present invention is to provide silver solder. By improving the structure of silver solder, the present invention solves the processing problems of high-nickel silver solder, obtains silver solder with a high nickel content, can maintain a relatively low liquidus temperature, and has the advantage of high cleanliness, resulting in high shear strength of the brazed structure when used for brazing multi-phase brazed structures.

[0008] A second objective of the present invention is to provide a method for preparing the above-mentioned silver solder. This method can process silver solder with a nickel content of more than 20 wt%, has a simple preparation process, and overcomes the technical bottleneck of difficulty in preparing high-nickel, high-performance silver solder. [Means for solving the problem]

[0009] In order to achieve the above-mentioned objectives of the present invention, a particular technical proposal is adopted.

[0010] Silver solder, wherein the silver solder is in the form of a foil-like silver solder containing several nickel layers, or a linear silver solder containing several nickel cores, the foil-like silver solder containing several nickel layers and several silver alloy layers, the nickel layers and silver alloy layers being arranged alternately, the outermost layer being the silver alloy layer, and the linear silver solder containing several nickel cores and several silver alloy portions enclosing the nickel cores on the outside.

[0011] Provided is the above-described method for preparing silver solder. The preparation method includes: step S1 of calculating the mass of nickel in the silver solder and the mass of the remaining solder metal based on the total mass of the silver solder and the mass fraction of each component; determining the size of the mold, and calculating the total thickness of the plate-shaped solder ingot and the thickness of a single nickel layer in the ingot, or calculating the radius of the columnar solder ingot and the radius of the nickel core in the ingot, based on the mass of the nickel, the mass of the remaining solder metal, and the number of nickel layers or nickel cores; step S3 of obtaining the corresponding number of the nickel layers or the nickel cores based on the size calculated in step S2; step S4 of applying colloidal graphite to the inner surface of the mold and fixing the nickel layer or the nickel core at appropriate positions in the cavity of the mold at intervals; step S5 of weighing each component in the remaining solder metal according to the mass ratio, melting and casting it as molten metal under the protection of an inert gas, injecting it into the cavity of the mold in step S4, cooling and demolding to obtain the plate-shaped solder ingot or the columnar solder ingot; and step S6 of performing hot rolling on the plate-shaped solder ingot to obtain a foil-shaped silver solder, or performing hot pressing, roll rolling, and drawing on the columnar solder ingot to obtain a wire-shaped silver solder.

Advantages of the Invention

[0012] Compared with the prior art, the present invention has the following beneficial effects.

[0013] (1) By designing the silver solder into a foil-shaped solder material containing a plurality of pure nickel layers or a wire-shaped solder material containing a plurality of pure nickel cores, the present invention can improve the processing performance of the silver solder with a high nickel content. The silver solder has a high nickel content of >20 wt%, and can maintain a relatively low melting temperature. And the silver solder has high cleanliness, with an oxygen content of <25 ppm, a N content of <7.5 ppm, and a H content of <4 ppm. When used for soldering with a multi-phase soldering structure, the shear strength of the silver solder according to the present invention is significantly improved compared with the conventional silver solder.

[0014] (2) The method according to the present invention has a simple preparation process. A plurality of nickel layers or a plurality of linear nickels are fixed inside the cavity of the mold, and then a nickel-free or low-nickel brazing filler metal molten metal is cast, demolded to obtain a plate-shaped or columnar brazing filler metal ingot, and a foil-shaped or linear high-nickel silver brazing filler can be obtained by a general processing method. It breaks through the technical bottleneck that the mass fraction of nickel is as high as 20% or more and it is difficult to prepare a high-nickel and high-performance silver brazing filler. As the reason for finally adding Hf powder and B powder in the form of being wrapped with copper foil, Hf can absorb gases such as oxygen gas and nitrogen gas as a getter agent, and B can remove oxide-based inclusions as a deoxidizer. Therefore, the powders of Hf and B have a large surface area, and if added finally, they can achieve the effects of deoxidation and degassing, contributing to obtaining a clean brazing filler metal. And by applying colloidal graphite to the inner surface of the polishing tool, instantaneous deoxidation can be performed during the casting of the molten metal, the brazing filler metal can be purified, and the cleanliness of the brazing filler metal can be improved. <​​​​​​​​​​​​​​​​​​​​

[0017] The technical aspects of the present invention will be clearly and completely described below with reference to the drawings and specific embodiments. The embodiments described are only some of the embodiments used to illustrate the present invention and do not limit the scope of the invention. All other embodiments that a person skilled in the art could obtain without using their inventive ability based on the embodiments of the present invention are also within the scope of the protection of the present invention. Where specific conditions are not specified in the embodiments, it is possible to perform the experiments under conventional conditions or conditions recommended by the manufacturer. Where the manufacturer of a reagent or instrument is not specified, it is possible to use commercially available conventional products.

[0018] As used herein, the term "and / or" describes a relationship between related objects, indicating that three types of relationships exist. For example, A and / or B describes three types of relationships: A exists alone, both A and B exist, and B exists alone.

[0019] As shown in Figure 1, a first aspect of the present invention provides a silver solder, which in form is a foil-like silver solder containing several nickel layers 11, or a linear silver solder containing several nickel cores 21.

[0020] The foil-like silver solder 1 contains several nickel layers 11 and several silver alloy layers 12, with the nickel layers 11 and silver alloy layers 12 arranged alternately, and the outermost layer being the silver alloy layer 12.

[0021] The linear silver solder 2 includes several nickel cores 21 and a silver alloy portion 22 that surrounds the nickel cores 21 on the outside.

[0022] This invention overcomes the technical limitation of difficulty in preparing silver solder with a high nickel content by designing the structure of the silver solder to be a foil-like silver solder containing multiple nickel layers or a linear silver solder containing multiple nickel cores, thereby enabling the production of high-strength silver solder with a nickel content of 20 wt% or more. The silver solder according to this invention has the advantages of a high nickel content, a low melting temperature, and high cleanliness, and when used for brazing multi-phase brazed structures, the shear strength of the brazed structure is significantly improved compared to conventional silver solder.

[0023] In some specific embodiments of the present invention, several nickel layers 11 are identical and are uniformly distributed in the thickness direction of the foil-like silver solder 1.

[0024] In some specific embodiments of the present invention, several nickel cores 21 are identical and uniformly distributed in the linear silver solder 2, that is, one of the nickel cores 21 is located at the center of the linear silver solder 2, and the other nickel cores 21 are distributed in an annular manner around the central axis of the linear silver solder 2. The annularly distributed nickel cores 21 may be in one layer (see Figure 1) or multiple layers. Multiple nickel cores 21 within the same annulus are distributed at equal angles around the central axis of the linear silver solder 2, and the multilayer annulus formed by the nickel cores 21 is distributed at equal intervals in the radial direction.

[0025] In some specific embodiments of the present invention, the foil-shaped silver solder 1 has one metallurgical reaction bonding layer between the nickel layer 11 and the silver alloy layer 12, and the number of nickel layers 11 is three or more, for example, three, four or five nickel layers 11 may be provided. and / or, the linear silver solder 2 has one metallurgical reaction bonding layer between the nickel core 21 and the silver alloy portion 22, and the number of nickel cores 21 is three or more, for example, three, four or five nickel cores 21 may be provided.

[0026] The metallurgical reaction bonding layer is a reaction bonding layer formed when a nickel layer or nickel core comes into contact with and partially dissolves in the molten silver alloy (i.e., the solder components other than nickel) during the preparation process. The purpose of having three or more nickel layers 11 or nickel cores 21 is to improve the uniformity of the nickel distribution in the silver solder, thereby allowing the silver and nickel to mix more uniformly after the solder melts.

[0027] In some specific embodiments of the present invention, the thickness of the foil-like silver solder 1 is 0.1 mm to 0.5 mm, and can be a value in the range of any one or any two of the following values: 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, and 0.5 mm.

[0028] In some specific embodiments of the present invention, in the foil-like silver solder 1, the nickel layer is uniformly distributed in the solder material in the thickness direction. The thickness of one nickel layer 11 accounts for 1 / 15 to 1 / 7 of the total thickness of the foil-like silver solder 1, and can be a value in the range of any one or any two of the following values: 1 / 15, 1 / 14, 1 / 13, 1 / 12, 1 / 11, 1 / 10, 1 / 9, 1 / 8, and 1 / 7.

[0029] In some specific embodiments of the present invention, the diameter of the linear silver solder 2 is 1.5 mm to 3.0 mm, and may be a value in the range of any one or any two of the following values: 1.5 mm, 2.0 mm, 2.5 mm, and 3.0 mm.

[0030] In some specific embodiments of the present invention, in the linear silver solder 2, the diameter of the nickel core 21 accounts for 1 / 4 to 1 / 3 of the total diameter of the entire linear silver solder 2, and may be a value in the range of any one or any two of the following values: 1 / 4, 1 / 3.9, 1 / 3.7, 1 / 3.5, 1 / 3.2, and 1 / 3.

[0031] In some specific embodiments of the present invention, the Ni content in the silver solder is greater than 20%, and may be in the range of any one or any two of the following values: 21%, 22.2%, 23.1%, 25.2%, 29.4%, 32.2%, and 39.4%, or any other value within the range.

[0032] and / or, in the silver solder, the O content is less than 25 ppm, the N content is less than 7.5 ppm, and the H content is less than 4 ppm. The silver solder according to the present invention has low O, N, and H content and is very clean.

[0033] In some specific embodiments of the present invention, the silver solder contains, by mass fraction, 60% to 75% of Ag, Cu, and Zn in stoichiometric proportions, 0.05% to 0.5% of Hf, 0.05% to 0.3% of B, and 0.5% to 2% of Cr and Zr in stoichiometric proportions, with the remainder being Ni.

[0034] By adding Hf, an element with strong hydrogen extraction ability, and B, an element with strong oxygen extraction ability, to silver solder, hydrogen and oxygen are removed from the solder material, improving the cleanliness of the solder material, reducing defects in the brazed joint, and increasing the strength of the brazed joint. Furthermore, since B can significantly refine the crystal grains of the solder material, the strength of the brazed joint can be further increased.

[0035] In some embodiments, and as representative and non-limiting examples, in silver solder, the total mass fraction of Ag, Cu, and Zn may be any one or any two values ​​from 60%, 65%, 70%, 72%, and 75%; the mass fraction of Hf may be any one or any two values ​​from 0.05%, 0.1%, 0.3%, and 0.5%; the mass fraction of B may be any one or any two values ​​from 0.05%, 0.1%, 0.2%, and 0.3%; and the total mass fraction of Cr and Zr may be any one or any two values ​​from 0.5%, 1%, 1.5%, and 2%.

[0036] In some specific embodiments of the present invention, the mass ratio of Ag, Zn, and Cu is 25:35:40, i.e., Zn:Cu = 35:40 and Ag:(Zn+Cu) = 1:3. The purpose of setting it this way is to make the ternary alloy have the lowest liquidus temperature and not contain a brittle phase. Specifically, when Zn:Cu = 35:40, as can be seen from the copper-zinc binary phase diagram, the alloy contains only the highly plastic α phase and almost no hard-brittle β phase, resulting in good plastic workability of the brazing material. When the mass ratio of silver to stoichiometric Zn and Cu (Zn:Cu=35:40) is 1:3, as can be seen from the ternary phase diagram, the minimum liquidus temperature of the Ag, Cu, Zn ternary alloy is approximately 790°C. When Ni and other elements are added to this ternary alloy, the resulting brazing alloy has the lowest liquidus temperature and the best brazing process performance.

[0037] In some specific embodiments of the present invention, the mass ratio of Cr to Zr in silver solder is 1.5 to 2.5:1, and can be any one or any two of the following values: 1.5:1, 1.7:1, 2:1, 2.3:1, and 2.5:1.

[0038] The purpose of keeping the mass ratio of Cr to Zr between 1.5 and 2.5:1 is to allow the formation of Cr2Zr by increasing the molar ratio of Cr to Zr to over 2:1, while also allowing the excess Cr to precipitate as dispersed particles. This forms dispersed solid solution strengthening particles of Cr and Cr2Zr at the brazed joint, thereby increasing the strength of the brazed joint. However, if there is too much Cr, the brittleness of the brazing material increases, so it is necessary to keep the mass ratio of Cr to Zr within a reasonable range.

[0039] In some specific embodiments of the present invention, the melting temperature of the silver solder is 700°C to 790°C, and may be a range of any one or any two of the following values: 700°C, 720°C, 750°C, 770°C, and 790°C.

[0040] In an Ag brazing material, when the Ag content is approximately 15% to 25% (with a melting temperature range of 700°C to 790°C), adding Ni can significantly increase the liquidus temperature of the brazing material, with the liquidus temperature rising by approximately 6°C for every 1% Ni added. In conventional methods, it is difficult to uniformly add too much nickel, and the liquidus temperature of the brazing material rises significantly (when 20% nickel is added, the liquidus temperature of the brazing material rises to 910°C). The present invention prevents the rise in the liquidus temperature of the original brazing material due to Ni by utilizing a configuration in which nickel layers and silver alloy layers are arranged alternately, or in which multiple nickel cores are uniformly distributed at intervals within the silver alloy portion. Specifically, because the melting temperature of the silver alloy layer or silver alloy portion is relatively low, the silver alloy layer outside the nickel layer or the silver alloy portion surrounding the nickel core can be melted at a relatively low temperature. Furthermore, because a single nickel layer is very thin and a single nickel core is very fine, during the heating and melting process, it melts into the surrounding silver alloy, forming a high-nickel silver solder in place. This allows for the melting and welding of the high-nickel solder at the melting temperature of the original silver alloy itself, improving the feasibility of the brazing operation and preventing thermal damage to the brazed parts.

[0041] A second aspect of the present invention provides a method for preparing silver solder according to any one of the embodiments described above. The preparation method includes the following steps.

[0042] Step S1: Calculate the mass of nickel in the silver solder and the mass of the remaining soldering metal based on the total mass of the silver solder and the mass fraction of each component.

[0043] Step S2: Determine the size of the mold, and based on the mass of nickel, the mass of the remaining brazing metal, and the number of nickel layers or nickel cores, calculate the total thickness of the plate-shaped brazing ingot and the thickness of a single nickel layer in the ingot, or calculate the radius of the columnar brazing ingot and the radius of the nickel core in the ingot.

[0044] Step S3: Based on the size calculated in Step S2, obtain a corresponding number of nickel layers or nickel cores.

[0045] Step S4: Apply colloidal graphite to the inner surface of the mold and fix the nickel layer or nickel core in the appropriate position within the mold cavity with spacing between them.

[0046] Step S5: Each component of the remaining brazing metal is weighed according to its mass ratio, melted as molten metal under the protection of an inert gas, injected into the cavity of the mold in Step S4, cooled and demolded to obtain a plate-shaped brazing ingot or a columnar brazing ingot.

[0047] Step S6: The plate-shaped solder ingot is subjected to multiple hot-rolling passes to obtain foil-like silver solder with a thickness of 0.1 mm to 0.5 mm, or the columnar solder ingot is subjected to hot pressing, roll rolling, and drawing to obtain wire-like silver solder with a diameter of 1.5 mm to 3.0 mm.

[0048] The method according to the present invention has a simple preparation process in which multiple foil-shaped nickel layers or multiple linear nickel cores are fixed at intervals inside the cavity of a mold, the remaining molten metal of the brazing material is poured in, and the mold is demolded to obtain a multi-layer plate-shaped brazing material ingot or a columnar brazing material ingot having multiple nickel cores. Then, foil-shaped silver brazing material or linear silver brazing material with a high nickel content can be obtained by a general processing method, with a nickel content of 20 wt% or more. This solves the problem of high-nickel silver brazing material being highly brittle and difficult to process, and also keeps the liquidus temperature of the high-nickel silver brazing material relatively low, preventing a significant rise in liquidus temperature caused by an increase in Ni content.

[0049] In step S4, the purpose of applying colloidal graphite to the inner surface of the mold is to purify the brazing material, which allows for instantaneous oxygen extraction during casting and improves the cleanliness of the brazing material.

[0050] In the ingot of step S5, the portion filled with the remaining solder metal is a silver alloy layer or silver alloy portion.

[0051] In some specific embodiments of the present invention, in step S1, the remaining solder metal refers to other raw materials in silver solder other than nickel, and includes Ag, Cu, Zn, Hf, B, Cr, and Zr.

[0052] In some specific embodiments of the present invention, in step S2, the thickness of a single nickel layer in a plate-shaped brazing ingot accounts for 1 / 15 to 1 / 7 of the total thickness of the ingot and may be a value in the range of any one or any two of the following: 1 / 15, 1 / 14, 1 / 13, 1 / 12, 1 / 11, 1 / 10, 1 / 9, 1 / 8, 1 / 7. And / or, the diameter of the nickel core in a columnar brazing ingot accounts for 1 / 4 to 1 / 3 of the total diameter of the ingot and may be a value in the range of any one or any two of the following: 1 / 4, 1 / 3.9, 1 / 3.7, 1 / 3.5, 1 / 3.2, 1 / 3.

[0053] In some specific embodiments of the present invention, in step S3, the nickel layer or nickel core may be a commercially available nickel foil or nickel wire, or one obtained by melting, casting, pressing or rolling metallic nickel.

[0054] In some specific embodiments of the present invention, in step S4, the nickel layer or nickel core is fixed in the mold cavity by spot welding and is uniformly distributed within the mold cavity.

[0055] In some specific embodiments of the present invention, in step S5, Cr in the remaining brazing metal can be added in the form of a Cu10Cr intermediate alloy and / or Zr can be added in the form of a Cu20Zr intermediate alloy, which can be added precisely in alloy form.

[0056] In some specific embodiments of the present invention, in step S5, Hf is added to the remaining brazing metal in the form of Hf powder, and B is added in the form of B powder.

[0057] In some specific embodiments of the present invention, the particle size of both Hf powder and B powder is 0.05 mm to 0.25 mm, and can be any one or any two of the following values: 0.05 mm, 0.10 mm, 0.15 mm, 0.20 mm, and 0.25 mm. Hf powder and B powder are getter and deoxidizer agents, respectively, and if the particle sizes of both are too large, the specific surface area decreases, reducing the dehydrogenation and deoxygenation effects. Therefore, it is necessary to rationally control the particle sizes of Hf and B.

[0058] In some specific embodiments of the present invention, Hf powder and B powder are added last in the form of being wrapped in copper foil. Degassing is usually performed in the final stage, and adding Hf powder and B powder last results in a significant dehydrogenation and deoxygenation effect. When Hf powder and B powder are added directly to the molten metal, they float on top and are distributed unevenly, reducing the effectiveness of dehydrogenation and oxygen removal. In the present invention, by adding Hf powder and B powder in the form of being wrapped in copper foil, the Hf powder and B powder wrapped in copper foil can sink into the molten metal, allowing for a more uniform distribution and resulting in a better dehydrogenation and oxygen removal effect.

[0059] In some specific embodiments of the present invention, the step between step S5 and step S6 further includes a homogenization annealing treatment of a plate-shaped brazing material ingot or a columnar brazing material ingot. The annealing temperature is 450°C to 580°C, and may be a range of any one or any two values ​​from, for example, 450°C, 480°C, 500°C, 530°C, 550°C, and 580°C. The annealing time is 3 hours to 5 hours, and may be a range of any one or any two values ​​from, for example, 3 hours, 3.5 hours, 4 hours, 4.5 hours, and 5 hours.

[0060] Below, several embodiments of the present invention will be described in detail using specific examples. Unless otherwise specified, the raw materials used in the examples can all be commercially available.

[0061] Example 1 A foil-like silver solder was prepared. The foil-like silver solder is composed of alternating nickel layers and silver alloy layers, with the outermost layer being the silver alloy layer and there being three nickel layers.

[0062] The silver solder contains, by mass fraction, 60% Ag, Zn, and Cu in stoichiometric composition, 0.05% Hf, 0.05% B, 0.5% Cr, Zr, and 39.4% Ni in stoichiometric composition. Here, Zn:Cu = 35:40 and Ag:(Cu+Zn) = 1:3, which calculates to be 15% Ag, 24% Cu, and 21% Zn. The mass ratio of Cr to Zr is 1.5:1, and the particle size of both Hf and B powders was 0.05 mm.

[0063] Preparation of foil-like silver solder: Step S1: The total mass of the brazing material was determined to be 50 kg. Based on the mass ratio, the mass of nickel was calculated to be 19.7 kg, and the mass of the remaining brazing metal was calculated to be 30.3 kg.

[0064] Step S2: The mold cavity size is 500mm in length and 400mm in height, and the nickel density is 8.9g / cm³. 3 Therefore, based on the density and mass of each element in the remaining brazing metal, the density of the remaining brazing metal is 8.9 g / cm³. 3 This was calculated to be the case.

[0065] 50cm x 40cm x L ニッケル ×8.9g / cm 3 Based on the formula = 19700g, the total thickness L of the nickel layer in a plate-shaped brazing ingot is calculated. ニッケル The thickness is 11 mm, and the thickness of one nickel layer is l ニッケル =L ニッケル The calculation was that / 3 = 3.66 mm.

[0066] 50 cm × 40 cm × L 銀 × 8.9 g / cm 3 Based on the formula of = 30300 g, the total thickness L of the silver alloy layer in the plate-shaped brazing material ingot 銀 was calculated to be 17 mm.

[0067] The total width of the cavities of the required mold was 28 mm.

[0068] Step S3: Weigh 19.7 kg of pure nickel, and through melting, casting, and rolling under the protection of an inert gas, obtain a nickel foil with a length of 1500 mm, a width of 400 mm, and a thickness of 3.66 mm, and then cut it into three nickel layers of 500 mm × 400 mm × 3.66 mm.

[0069] Step S4: Open the split cast iron mold, apply colloidal graphite to the inner surface of the mold, and fix the three nickel layers prepared in Step S3 at the bottom of the cavity of the mold so as to be uniformly distributed by spot welding.

[0070] Step S5: Weigh the Ag, Cu, Zn, Hf, B, Cr, Zr raw materials in the remaining brazing material metal according to the mass ratio, melt them into molten metal by melting under the protection of an inert gas. Here, Cr and Zr are added in the form of Cu10Cr and Cu20Zr intermediate alloys respectively, and Hf powder and B powder are finally added in the form of being wrapped with copper foil. Inject the molten metal into the cavity of the mold, and after cooling and demolding, obtain a multi-layer plate-shaped brazing material ingot.

[0071] Step S6: Place the multi-layer plate-shaped brazing material ingot in a box-type resistance furnace, perform a homogenization annealing treatment at 450 °C for 5 hours, and perform multiple passes of hot rolling to obtain a foil-shaped silver brazing material with a thickness of 0.1 mm.

[0072] Example 2 A foil-shaped silver brazing material was prepared. The foil-shaped silver brazing material is composed of nickel layers and silver alloy layers arranged alternately, the outermost layer is a silver alloy layer, and the number of nickel layers is 4 layers.

[0073] The silver solder contains, by mass fraction, 65% Ag, Zn, and Cu, 32.2% Ni, 0.5% Hf, 0.3% B, and 2% Cr and Zr in stoichiometric proportions. Here, Zn:Cu = 35:40 and Ag:(Cu+Zn) = 1:3, resulting in calculated Ag 16.25%, Cu 26%, and Zn 22.75%. The mass ratio of Cr to Zr is 2:1, and the particle size of both B powder and Hf powder was 0.25 mm.

[0074] Preparation of foil-like silver solder: Step S1: The total mass of the brazing material was determined to be 100 kg. Based on the mass ratio, the mass of nickel was calculated to be 32.2 kg, and the mass of the remaining brazing metal was calculated to be 67.8 kg.

[0075] Step S2: The mold cavity size is 500mm in length and 400mm in height, and the nickel density is 8.9g / cm³. 3 Therefore, based on the density and mass of each element in the remaining brazing metal, the density of the remaining brazing metal is 8.9 g / cm³. 3 This was calculated to be the case.

[0076] 50cm x 40cm x L ニッケル ×8.9g / cm 3 Based on the formula =32200g, the total thickness L of the nickel layer in a plate-shaped brazing ingot is calculated. ニッケル The thickness is 18 mm, and the thickness of one nickel layer is l ニッケル =L ニッケル The calculation was that / 4 = 4.5 mm.

[0077] 50cm x 40cm x L 銀 ×8.9g / cm 3 Based on the formula = 67800g, the total thickness L of the silver alloy layer in a plate-shaped solder ingot is calculated. 銀 It was calculated to be 38mm.

[0078] The total width of the required mold cavity was 56 mm.

[0079] Step S3: 32.2 kg of pure nickel was weighed, melted, cast, and rolled under the protection of an inert gas to obtain a nickel foil measuring 2000 mm in length, 400 mm in width, and 4.5 mm in thickness, and then cut into four nickel layers measuring 500 mm × 400 mm × 4.5 mm.

[0080] Step S4: The two-part cast iron mold was opened, colloidal graphite was applied to the inner surface of the mold, and the four nickel layers prepared in Step S3 were fixed by spot welding so that they were uniformly distributed at the bottom of the mold cavity.

[0081] Step S5: The Ag, Cu, Zn, Hf, B, Cr, and Zr raw materials in the remaining brazing metal were weighed according to their mass ratio and melted into the molten metal by melting under the protection of an inert gas. Here, Cr and Zr were added in the form of Cu10Cr and Cu20Zr intermediate alloys, respectively, and finally, Hf powder and B powder were added in the form of copper foil. The molten metal was poured into the cavity of the mold, cooled and demolded to obtain a multi-layered plate-like brazing ingot.

[0082] Step S6: A multi-layered plate-shaped solder ingot was placed in a box-type resistance furnace and subjected to homogenization annealing at 450°C for 4 hours, followed by multiple hot-rolling passes to obtain a foil-like silver solder with a thickness of 0.5 mm.

[0083] Example 3 A linear silver solder was prepared, consisting of three nickel cores and a silver alloy portion that encloses the three nickel cores on the outside.

[0084] The silver solder contains, by mass fraction, 70% Ag, Zn, and Cu, 29.4% Ni, 0.05% Hf, 0.05% B, and 0.5% Cr and Zr in stoichiometric proportions. Here, Zn:Cu = 35:40 and Ag:(Cu+Zn) = 1:3, resulting in calculated Ag 17.5%, Cu 28%, and Zn 24.5%. The mass ratio of Cr to Zr is 2.5:1, and the particle size of the Hf and B powders was 0.05 mm.

[0085] Preparation of linear silver solder: Step S1: The total mass of the brazing material was determined to be 10 kg. Based on the mass ratio, the mass of nickel was calculated to be 2.94 kg, and the mass of the remaining brazing metal was calculated to be 7.06 kg.

[0086] Step S2: The mold cavity is cylindrical, with a height of 400 mm, and the nickel density is 8.9 g / cm³. 3 Therefore, based on the density and mass of each element in the remaining brazing metal, the density of the remaining brazing metal is 8.9 g / cm³. 3 This was calculated to be the case.

[0087] π × r 2 ×40cm × 8.9g / cm 3 Based on the formula ×3 = 2940g, the radius r of the nickel core in the columnar brazing rod ingot was calculated to be 9.4mm.

[0088] (π×R 2 ×40cm-π×r 2 (40cm x 3) x 8.9g / cm 3 Based on the formula =7060g, the total radius R of the columnar brazing material ingot was calculated to be 29.9mm.

[0089] The required cavity radius for the mold was 29.9 mm.

[0090] Step S3: 2.94 kg of pure nickel was weighed, melted, cast, pressed, and drawn under the protection of an inert gas to obtain a nickel wire 1200 mm long with a radius of 9.4 mm, and then cut into three nickel cores 400 mm long with a radius of 9.4 mm.

[0091] Step S4: The two-part cast iron mold was opened, colloidal graphite was applied to the inner surface of the mold, and the three nickel cores prepared in Step S3 were fixed by spot welding so that they were uniformly distributed at the bottom of the mold cavity.

[0092] Step S5: The raw materials Ag, Cu, Zn, Hf, B, Cr, and Zr in the remaining brazing metal were weighed according to their mass ratios and melted into the molten metal by melting under the protection of an inert gas. Here, Cr and Zr were added in the form of Cu10Cr and Cu20Zr intermediate alloys, respectively, and finally, Hf powder and B powder were added in the form of copper foil. The molten metal was poured into the cavity of the mold, cooled and demolded to obtain a columnar brazing ingot having multiple nickel cores.

[0093] Step S6: A columnar solder ingot having multiple nickel cores was placed in a box-type resistance furnace and subjected to homogenization annealing at 450°C for 5 hours. After pressing and drawing, a linear silver solder with a diameter of 1.5 mm was obtained.

[0094] Example 4 A linear silver solder was prepared, consisting of four nickel cores and a silver alloy portion that encloses the four nickel cores on the outside.

[0095] The silver solder contains, by mass fraction, 72% Ag, Zn, and Cu, 25.2% Ni, 0.5% Hf, 0.3% B, and 2% Cr and Zr in stoichiometric proportions. Here, Zn:Cu = 35:40 and Ag:(Cu+Zn) = 1:3, resulting in calculated Ag 18%, Cu 28.8%, and Zn 25.2%. The mass ratio of Cr to Zr is 2:1, and the particle size of both Hf and B powders was 0.25 mm.

[0096] Preparation of linear silver solder: Step S1: The total mass of the brazing material was determined to be 10 kg. Based on the mass ratio, the mass of nickel was calculated to be 2.52 kg, and the mass of the remaining brazing metal was calculated to be 7.48 kg.

[0097] Step S2: The mold cavity is cylindrical, with a height of 400 mm, and the nickel density is 8.9 g / cm³. 3 Therefore, based on the density and mass of each element in the remaining brazing metal, the density of the remaining brazing metal is 8.9 g / cm³. 3 This was calculated to be the case.

[0098] π × r 2 ×40cm × 8.9g / cm 3 Based on the formula ×4 = 2520g, the radius r of the nickel core in the columnar brazing rod ingot was calculated to be 7.5mm.

[0099] (π×R 2 ×40cm-π×r 2 (40cm x 4) x 8.9g / cm 3 Based on the formula =7480g, the total radius R of the columnar brazing rod ingot was calculated to be 30mm.

[0100] The required cavity radius for the mold was 30 mm.

[0101] Step S3: 2.52 kg of pure nickel was weighed, melted, cast, pressed, and drawn under the protection of an inert gas to obtain a nickel wire 1600 mm long with a radius of 7.5 mm, and then cut into four nickel cores 7.5 mm in radius and 400 mm in length.

[0102] Step S4: The two-part cast iron mold was opened, colloidal graphite was applied to the inner surface of the mold, and the four nickel cores prepared in Step S3 were fixed to the bottom of the mold cavity by spot welding so that they were uniformly distributed.

[0103] Step S5: The raw materials Ag, Cu, Zn, Hf, B, Cr, and Zr in the remaining brazing metal were weighed according to their mass ratios and melted into the molten metal by melting under the protection of an inert gas. Here, Cr and Zr were added in the form of Cu10Cr and Cu20Zr intermediate alloys, respectively, and finally, Hf powder and B powder were added in the form of copper foil. The molten metal was poured into the cavity of the mold, cooled and demolded to obtain a columnar brazing ingot having multiple nickel cores.

[0104] Step S6: A columnar solder ingot having multiple nickel cores was placed in a box-type resistance furnace and subjected to homogenization annealing at 580°C for 3 hours. After pressing and drawing, a linear silver solder with a diameter of 3.0 mm was obtained.

[0105] Example 5 A linear silver solder was prepared, consisting of three nickel cores and a silver alloy portion that encloses the three nickel cores on the outside.

[0106] The silver solder contains, by mass fraction, 75% Ag, Zn, and Cu, 23.1% Ni, 0.3% Hf, 0.1% B, and 1.5% Cr and Zr in stoichiometric proportions. Here, it was calculated that Ag was 18.75%, Cu 30%, and Zn 26.25%, the mass ratio of Cr to Zr was 2:1, and the particle size of both Hf and B powders was 0.20 mm.

[0107] Preparation of linear silver solder: Step S1: The total mass of the brazing material was determined to be 10 kg. Based on the mass ratio, the mass of nickel was calculated to be 2.31 kg, and the mass of the remaining brazing metal was calculated to be 7.69 kg.

[0108] Step S2: The mold cavity is cylindrical, with a height of 400 mm, and the nickel density is 8.9 g / cm³. 3 Therefore, based on the density and mass of each element in the remaining brazing metal, the density of the remaining brazing metal is 8.6 g / cm³. 3 This was calculated to be the case.

[0109] π × r 2 ×40cm × 8.9g / cm 3 Based on the formula ×3 = 2310g, the radius r of the nickel core in the columnar brazing rod ingot was calculated to be 8.3mm.

[0110] (π×R 2 ×40cm-π×r 2 (40cm x 3) x 8.6g / cm 3 Based on the formula =7690g, the total radius R of the columnar brazing rod ingot was calculated to be 30mm.

[0111] The required cavity radius for the mold was 30 mm.

[0112] Step S3: 2.31 kg of pure nickel was weighed, melted, cast, pressed, and drawn under the protection of an inert gas to obtain a nickel wire 1200 mm long with a radius of 8.3 mm, and then cut into three nickel cores 400 mm long with a radius of 8.3 mm.

[0113] Step S4: The two-part cast iron mold was opened, colloidal graphite was applied to the inner surface of the mold, and the three nickel cores prepared in Step S3 were fixed by spot welding so that they were uniformly distributed at the bottom of the mold cavity.

[0114] Step S5: The raw materials Ag, Cu, Zn, Hf, B, Cr, and Zr in the remaining brazing metal were weighed in mass ratio and melted into the molten metal by melting under the protection of an inert gas. Here, Cr and Zr were added in the form of Cu10Cr and Cu20Zr intermediate alloys, respectively, and finally Hf powder and B powder were added in the form of copper foil. The molten metal was poured into the cavity of the mold, cooled and demolded to obtain a columnar brazing ingot having multiple nickel cores.

[0115] Step S6: A columnar solder ingot having multiple nickel cores was placed in a box-type resistance furnace and subjected to homogenization annealing at 530°C for 4.5 hours. After pressing and drawing, a linear silver solder with a diameter of 2.5 mm was obtained.

[0116] Comparative Example 1 Comparative Example 1 had the exact same silver solder components as Example 1, but differed in that Ni was added in the usual form, and an ingot was formed by mixing, melting, and casting all the raw materials using conventional methods (colloidal graphite was not applied to the mold), and then a foil-like solder material was prepared by hot rolling. Due to the high nickel content, most of the nickel precipitated during melting and could not be dissolved in the solder alloy, and the high brittleness of the solder material, only a foil-like solder material with a thickness of 1 mm could be obtained, and a foil-like solder material with a thickness of 0.1 mm could not be obtained.

[0117] Comparative Example 2 Comparative Example 2 differed from Example 1 in that Cr and Zr were not added, but all other conditions were the same as in Example 1.

[0118] Comparative Example 3 Comparative Example 3 differed from Example 1 in that colloidal graphite was not applied inside the mold, but all other conditions were the same as in Example 1.

[0119] Comparative Example 4 Comparative Example 4 differed from Example 1 in that the mass ratio of Cr to Zr was 1:1, while all other conditions were the same as in Example 1.

[0120] Comparative Example 5 Comparative Example 5 differed from Example 1 in that the Hf powder and B powder were added first in a form wrapped in copper foil, but all other conditions were the same as in Example 1.

[0121] Comparative Example 6 Comparative Example 6 differed from Example 1 in that the mass ratio of Cr to Zr was 4:1, while all other conditions were the same as in Example 1.

[0122] Comparative Example 7 Comparative Example 7 differed from Example 1 in that the particle size of both Hf powder and B powder was greater than 0.25 mm, while all other conditions were the same as in Example 1.

[0123] Comparative Example 8 Comparative Example 8 differed from Example 1 in that Hf and B were not added, but all other conditions were the same as in Example 1.

[0124] Comparative Example 9 Comparative Example 9 had the same silver solder composition as Example 3, but differed from Example 3 in that Ni was added in the usual form, and an ingot was formed by mixing, melting, and casting all the raw materials using a conventional method (colloidal graphite was not applied to the mold), and then a wire-shaped solder was prepared by hot pressing and drawing. The nickel content was high, and not all of the nickel could be dissolved into the alloy during melting. Furthermore, the solder was highly brittle, and only a wire-shaped solder with a diameter of 10 mm could be formed by drawing, and it was not possible to obtain a wire-shaped solder with a diameter of 3 mm or less.

[0125] Comparative Example 10 Comparative Example 10 differs from Example 1 in that the mass ratios of Ag, Cu, and Zn are different. In Comparative Example 10, Zn:Cu = 1:1 and Ag:(Zn+Cu) = 1:3, and all other conditions were the same as in Example 1. In this case, the Zn content in the brazing alloy was high, resulting in a large amount of β-brittle phase and degraded processing performance.

[0126] Comparative Example 11 Using conventional silver solder, the ratio of Ag:Zn:Cu was 25:35:40. In mass fraction, the silver solder in Comparative Example 11 contained 20% Ag, 25% Zn, 2% Ni, 0.05% Hf, 0.05% B, 0.5% Cr and Zr in stoichiometric proportions, with the remainder being copper. Here, the mass ratio of Cr to Zr was 2:1. Using a conventional method, all raw materials were induced melted in air to obtain molten metal, which was injected into a mold without colloidal graphite coating. After cooling and demolding, a single-layer plate-shaped solder ingot was obtained. After annealing, multiple hot-rolling passes were performed to obtain a foil-shaped silver solder with a thickness of 0.1 mm. Other parameters and conditions were the same as in Example 1. The obtained solder had a liquidus temperature exceeding 900°C, which is unfavorable for welding and prone to thermal damage to the base material of the workpiece.

[0127] Test Example 1 To test the brazing performance of the silver solder according to each example and comparative example of the present invention, brazing was performed on YG6X hard alloy and 65Mn steel using the silver solder according to each example and comparative example, using induction brazing. In Examples 1-5, Comparative Examples 2-8, and Comparative Example 10, the brazing temperature was set to 820°C-840°C, and in Comparative Examples 1, 9, and 11, the brazing temperature was set to 930°C-950°C due to the high liquidus temperature of the solder material, with a holding time of 5 minutes in all cases. Twenty samples were welded, and the shear strength of the brazed structure (the part formed by brazing) was measured, and the average value was calculated. The measurement results are shown in Table 1.

[0128] [Table 1]

[0129] As can be seen from the data in Table 1, the brazed structure brazed with the brazing material according to the example has much higher strength than the brazed structure brazed with the brazing material according to the comparative example. In particular, the shear strength of the brazed structure brazed with the brazing material according to Example 2 was high at 355.3 MPa, which is about 64% higher than the shear strength of the conventional silver brazing structure brazed with 216.4 MPa (Comparative Example 11).

[0130] Test Example 2 To test the cleanliness of the silver solder in each example and comparative example, nitrogen, hydrogen, and oxygen analysis tests were performed on each solder material. Each sample was measured three times, and the average value was calculated. The measurement results are shown in Table 2.

[0131] [Table 2]

[0132] As can be seen from the data in Table 2, the silver solders produced in Examples 1-5 had relatively low O, N, and H content. Compared to conventional silver solder (Comparative Example 11), the oxygen content decreased from several hundred ppm to several tens of ppm, resulting in a significant reduction in the gas impurity content in the solder material.

[0133] As can be seen from Figures 2 and 3, the hard alloy turning tool brazed with silver solder according to Example 1 is of relatively good quality, while the hard alloy turning tool brazed with silver solder according to Comparative Example 1 has a relatively large number of pores on the surface of the welded joint, which shortens the service life of the turning tool.

[0134] Although the present invention has been described using specific examples, the above examples are merely for illustrating the technical concepts of the present invention and are not limiting. Those skilled in the art will be able to modify the technical concepts described in the above examples, or substitute some or all of their technical features, without departing from the spirit and scope of the present invention. These modifications or substitutions will not cause the technical concepts in question to deviate from the scope of the technical concepts in each example of the present invention. Therefore, the claims include all such substitutions and modifications that fall within the scope of the present invention. [Explanation of symbols]

[0135] 1. Foil-like silver solder 11 Nickel layer 12 Silver alloy layer 2. Linear silver solder 21 Nickel core 22 Silver alloy part

Claims

1. It is silver solder, The silver solder may take the form of a foil-like silver solder containing several nickel layers, or a linear silver solder containing several nickel cores. The foil-like silver solder comprises several nickel layers and several silver alloy layers, with the nickel layers and silver alloy layers arranged alternately, and the outermost layer being the silver alloy layer. The linear silver solder includes several nickel cores and several silver alloy portions that surround the nickel cores on the outside. A silver solder characterized by the following features.

2. In the foil-shaped silver solder, there is one metallurgical reaction bonding layer between the nickel layer and the silver alloy layer, and there are three or more nickel layers, and / or, in the linear silver solder, there is one metallurgical reaction bonding layer between the nickel core and the silver alloy portion, and there are three or more nickel cores. The silver solder according to feature 1.

3. (1) The thickness of the foil-like silver solder is 0.1 mm to 0.5 mm. (2) In the foil-shaped silver solder, the thickness of one nickel layer accounts for 1 / 15 to 1 / 7 of the total thickness of the foil-shaped silver solder. (3) The diameter of the wire-shaped silver solder is 1.5 mm to 3.0 mm. (4) In the linear silver solder, the diameter of the nickel core accounts for 1 / 4 to 1 / 3 of the total diameter of the linear silver solder. Includes at least one of the characteristics (1) to (4) The silver solder according to feature 1.

4. The Ni content in the aforementioned silver solder is more than 20%. and / or, in the silver solder, the O content is less than 25 ppm, the N content is less than 7.5 ppm, and the H content is less than 4 ppm. The silver solder according to feature 1.

5. The aforementioned silver solder contains, by mass fraction, 60% to 75% of Ag, Cu, and Zn in stoichiometric proportions, 0.05% to 0.5% of Hf, 0.05% to 0.3% of B, and 0.5% to 2% of Cr and Zr in stoichiometric proportions, with the remainder being Ni. The silver solder according to feature 1.

6. (1) The mass ratio of Ag, Zn, and Cu is 25:35:

40. (2) The mass ratio of Cr to Zr shall be 1.5 to 2.5:

1. It satisfies at least one of the characteristics (1) to (2). The silver solder according to feature 5.

7. The melting temperature of the aforementioned silver solder is 700°C to 790°C. The silver solder according to feature 5.

8. A method for preparing silver solder according to any one of claims 1 to 7, Step S1 calculates the mass of nickel in the silver solder and the mass of the remaining soldering metal based on the total mass of the silver solder and the mass fraction of each component. Step S2 involves determining the size of the mold, and calculating the total thickness of the plate-shaped brazing ingot and the thickness of a single nickel layer in the ingot based on the mass of the nickel, the mass of the remaining brazing metal, and the number of nickel layers or nickel cores, or calculating the radius of the columnar brazing ingot and the radius of the nickel core in the ingot. Step S3 involves obtaining a corresponding number of nickel layers or nickel cores based on the size calculated in step S2, Step S4 involves applying colloidal graphite to the inner surface of the mold and fixing the nickel layer or nickel core at intervals within the cavity of the mold. Step S5 involves weighing each component of the remaining brazing metal according to its mass ratio, melting it as molten metal under the protection of an inert gas, injecting it into the cavity of the mold in step S4, cooling and demolding to obtain the plate-shaped brazing ingot or the columnar brazing ingot, Step S6 includes hot rolling of the plate-shaped solder ingot to obtain foil-shaped silver solder, or hot pressing, roll rolling, and drawing of the columnar solder ingot to obtain wire-shaped silver solder. A method for preparing silver solder characterized by the following features.

9. In step S5, Cr is added to the remaining brazing metal in the form of a Cu10Cr intermediate alloy, and / or Zr is added in the form of a Cu20Zr intermediate alloy. The method for preparing silver solder according to feature 8.

10. In step S5, Hf and B are added to the remaining brazing metal in the form of Hf powder and B powder, respectively, and (1) The particle size of both the Hf powder and the B powder is 0.05 mm to 0.25 mm. (2) The Hf powder and the B powder are added last in a form that encases them in copper foil. It satisfies at least one of the characteristics (1) to (2). The method for preparing silver solder according to feature 8.

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