Silver solder and preparation method thereof

Abstract

The invention relates to the technical field of brazing materials, in particular to silver brazing filler metal and a preparation method thereof. The brazing filler metal of the silver brazing filler metal is in a foil shape containing a plurality of nickel layers or a strip shape containing a plurality of nickel cores; the foil-shaped silver solder comprises a plurality of nickel layers and a plurality of silver alloy layers, the nickel layers and the silver alloy layers are alternately arranged, and the outermost layer is the silver alloy layer; the strip-shaped silver brazing filler metal comprises a plurality of nickel cores and a silver alloy part wrapping the outer sides of the nickel cores. A plurality of nickel layers or a plurality of nickel cores are fixed in a mold cavity at intervals, a multi-layer plate-shaped or multi-nickel-core columnar cast ingot is obtained after the remaining brazing filler metal liquid is cast and demolded, foil-shaped silver brazing filler metal or strip-shaped silver brazing filler metal with the high nickel content can be obtained through a conventional machining mode, the nickel content can reach 20 wt% or above, and the nickel content can reach 20 wt% or above. The problem that the current high-nickel-silver brazing filler metal is difficult to process due to high brittleness is solved; and the silver solder provided by the invention is high in cleanliness, and the shear strength of a soldered joint can be remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of soldering materials, and in particular to a silver solder and a preparation method thereof. Background Art

[0002] Silver solder is the most widely used brazing filler metal at present. It has excellent process performance, suitable melting point, good wetting and gap filling ability, and excellent brazing filler metal and brazing seam strength, conductivity and corrosion resistance. Therefore, silver solder is widely used in brazing of heterogeneous alloy components such as cemented carbide tools and diamond tools. As the service environment of cemented carbide tools and diamond tools becomes more and more extreme and complex, higher requirements are placed on the comprehensive performance of silver solder, and it is urgent to develop high-performance silver solder.

[0003] Nickel is a common performance-enhancing element in silver solder. Adding 2% nickel by mass can significantly improve the strength of the solder and the solder joint. If the mechanical properties of the silver solder are to be greatly improved, the nickel content needs to be increased to more than 15%. However, when the nickel content is greater than 2.5%, the hardness and brittleness of the solder increases sharply, which seriously deteriorates the processing performance of the solder, and it is difficult to obtain a high-nickel and high-performance silver solder.

[0004] In addition, the existing silver solder has a low cleanliness level, which can easily lead to defects such as slag inclusions and pores in the brazed joints, resulting in a low brazing rate of the joints. The heterogeneous alloy components will fail prematurely during service, thus affecting the service life of the components.

[0005] In order to solve the above-mentioned deficiencies, it is necessary to develop a high-performance silver solder with high cleanliness, high brazing strength and high nickel content, which is suitable for high-reliability brazing of heterogeneous alloy components.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The first purpose of the present invention is to provide a silver solder. The present invention solves the processing problem of high-nickel silver solder by improving the structure of the silver solder, thereby obtaining a silver solder with a high nickel content and maintaining a low liquidus temperature. The silver solder also has the advantage of high cleanliness. When used for brazing heterogeneous joints, the shear strength of the brazed joint is high.

[0008] The second purpose of the present invention is to provide a method for preparing the silver solder as described above, which can process silver solder with a nickel content greater than 20wt% and has a simple preparation process, breaking through the technical bottleneck of the difficulty in preparing high-nickel and high-performance silver solder.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0010] A silver solder, wherein the solder is in the form of a foil containing a plurality of nickel layers or a strip containing a plurality of nickel cores;

[0011] The foil-like silver solder comprises a plurality of the nickel layers and a plurality of silver alloy layers, wherein the nickel layers and the silver alloy layers are arranged alternately, and the outermost layer is the silver alloy layer;

[0012] The strip-shaped silver solder comprises a plurality of nickel cores and a silver alloy portion wrapped around the outer sides of the plurality of nickel cores.

[0013] A method for preparing the silver solder as described above comprises the following steps:

[0014] S1. Calculate 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 percentage of each component;

[0015] S2. Determine the mold size, calculate the total thickness of the plate-shaped brazing ingot and the thickness of a single nickel layer in the ingot, or the radius of the columnar brazing ingot and the radius of the nickel core in the ingot according to the mass of the nickel, the mass of the remaining brazing metal, and the number of nickel layers or nickel cores;

[0016] S3. According to the size calculated in step S2, obtaining a corresponding number of the nickel layer or the nickel core;

[0017] S4. Coating graphite emulsion on the inner surface of the mold, fixing the nickel layer or the nickel core at intervals at appropriate positions in the mold cavity;

[0018] S5. Weigh the components of the remaining brazing filler metal according to the mass ratio, smelt them into molten metal under the protection of inert gas, and inject them into the mold cavity in step S4, and obtain the plate-shaped brazing filler ingot or the columnar brazing filler ingot after cooling and demolding;

[0019] S6. Hot-rolling the plate-shaped solder ingot to obtain foil-shaped silver solder; or hot-extruding, rolling, and drawing the columnar solder ingot to obtain strip-shaped silver solder.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The present invention configures the silver solder to be a foil solder containing multiple pure nickel layers or a strip solder containing multiple pure nickel cores. This structure can improve the processing performance of the silver solder with a high nickel content, so that the nickel content in the silver solder is as high as 20wt% or more, while maintaining a low melting point. In addition, the silver solder has a high cleanliness, an oxygen content of less than 25ppm, a N content of less than 7.5ppm, and a H content of less than 4ppm. Compared with traditional silver solders, the shear strength of the silver solder in the present invention is significantly improved when used for brazing heterogeneous joints.

[0022] (2) The preparation process of the method of the present invention is simple. A plurality of nickel layers or a plurality of nickel bars are fixed inside the mold cavity, and then the nickel-free or low-nickel solder molten metal is cast and demolded to obtain a plate-shaped or columnar solder ingot, and then a foil-shaped or strip-shaped high-nickel silver solder can be obtained by conventional processing methods. The mass proportion of nickel can reach more than 20%, breaking through the technical bottleneck of the difficult preparation of high-nickel and high-performance silver solder; Hf and B powders are added last in the form of copper foil wrapped. This is because Hf is a getter that can absorb gases such as oxygen and nitrogen, and B is a deoxidizer that can remove oxidative inclusions. Therefore, the powder surface area of ​​the two is large, and adding them last can play a role in deoxidation and degassing, which is helpful to obtain clean solder; at the same time, graphite emulsion is coated on the inner surface of the mold, which can instantly deoxidize the molten metal during casting, play a role in purifying the solder, and improve the cleanliness of the solder. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 A schematic diagram of the cross-sectional structure of a strip-shaped silver solder and a foil-shaped silver solder provided in an embodiment of the present invention;

[0025] Figure 2 This is a brazing morphology diagram of a cemented carbide turning tool brazed with silver brazing filler metal prepared in Example 1 of the present invention;

[0026] Figure 3 This is a brazing morphology diagram of a cemented carbide turning tool brazed with silver solder prepared in Comparative Example 1 of the present invention.

[0027] Reference numerals:

[0028] 1-foil-shaped silver solder; 11-nickel layer; 12-silver alloy layer; 2-strip-shaped silver solder; 21-nickel core; 22-silver alloy part. DETAILED DESCRIPTION

[0029] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0030] like Figure 1 As shown, the first aspect of the present invention provides a silver solder, the solder is in the form of a foil containing a plurality of nickel layers 11 or a strip containing a plurality of nickel cores 21;

[0031] The foil-like silver solder 1 comprises a plurality of nickel layers 11 and a plurality of silver alloy layers 12, wherein the nickel layers 11 and the silver alloy layers 12 are arranged alternately, and the outermost layer is the silver alloy layer 12;

[0032] The strip-shaped silver solder 2 includes a plurality of nickel cores 21 and a silver alloy portion 22 wrapped around the outer sides of the plurality of nickel cores 21 .

[0033] The present invention overcomes the technical limitation that silver solder with a high nickel content is difficult to prepare by designing the structure of the silver solder to be a foil-shaped silver solder containing multiple nickel layers or a strip-shaped silver solder containing multiple nickel cores, thereby obtaining a high-strength silver solder with a nickel content of more than 20wt%. The silver solder provided by the present invention has the advantages of high nickel content, low melting temperature and high cleanliness. When the silver solder is used for brazing heterogeneous joints, the shear strength of the brazed joint is significantly improved compared with traditional silver solders.

[0034] In some specific embodiments of the present invention, the plurality of nickel layers 11 are identical and are evenly distributed in the thickness direction of the foil-like silver solder 1 .

[0035] In some specific embodiments of the present invention, several nickel cores 21 are the same and are evenly distributed in the strip silver solder 2, that is, one of the nickel cores 21 is located at the center of the strip silver solder 2, and the remaining nickel cores 21 are distributed in a ring shape around the central axis of the strip silver solder 2. The nickel cores 21 distributed in a ring shape can be a layer (such as Figure 1 As shown), it can also be multi-layered, with multiple nickel cores 21 in the same circular ring distributed at equal angles around the central axis of the strip silver solder 2, and the multi-layer circular rings formed by the nickel cores 21 are distributed at equal intervals in the radial direction.

[0036] In some specific embodiments of the present invention, in the foil-like silver solder 1, there is a metallurgical reaction bonding layer between the nickel layer 11 and the silver alloy layer 12, and the number of the nickel layers 11 is ≥3, for example, the nickel layers 11 can be set to 3 layers, 4 layers or 5 layers, etc.; and / or, in the strip-like silver solder 2, there is a metallurgical reaction bonding layer between the nickel core 21 and the silver alloy part 22, and the number of the nickel cores 21 is ≥3, for example, the nickel cores 21 can be set to 3, 4 or 5, etc.

[0037] The metallurgical reaction bonding layer is a reaction bonding layer formed when the nickel layer or the nickel core contacts with the molten silver alloy (i.e., the remaining solder components other than nickel) and partially dissolves therein during the preparation process. The purpose of controlling the number of the nickel layer 11 or the nickel core 21 to be not less than 3 is to improve the uniformity of the distribution of nickel in the silver solder, so that the silver and nickel can be better mixed after the solder is melted.

[0038] In some specific embodiments of the present invention, the thickness of the foil-like silver solder 1 is 0.1-0.5 mm, for example, the thickness of the foil-like silver solder 1 can be any value among 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm or a range consisting of any two values;

[0039] In some specific embodiments of the present invention, in the foil-like silver solder 1, the nickel layer is evenly distributed in the solder along the thickness direction, and the thickness of a single nickel layer 11 accounts for 1 / 15 to 1 / 7 of the total thickness of the entire foil-like silver solder 1; for example, it can be any point value among 1 / 15, 1 / 14, 1 / 13, 1 / 12, 1 / 11, 1 / 10, 1 / 9, 1 / 8, 1 / 7, or a range value composed of any two point values.

[0040] In some specific embodiments of the present invention, the diameter of the strip silver solder 2 is 1.5-3.0 mm. For example, the diameter of the strip silver solder 2 can be any point value among 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm or a range value consisting of any two point values.

[0041] In some specific embodiments of the present invention, in the strip silver solder 2, the diameter of the nickel core 21 accounts for 1 / 4 to 1 / 3 of the total diameter of the entire strip silver solder 2, for example, it can be any point value among 1 / 4, 1 / 3.9, 1 / 3.7, 1 / 3.5, 1 / 3.2, 1 / 3, or a range value consisting of any two point values.

[0042] In some specific embodiments of the present invention, the Ni content in the silver solder is higher than 20%, for example, it can be any point value among 21%, 22.2%, 23.1%, 25.2%, 29.4%, 32.2%, 39.4%, or a range value consisting of any two point values, or other values ​​within the range;

[0043] And / or, the O content in the silver solder is less than 25ppm, the N content is less than 7.5ppm, and the H content is less than 4ppm. The silver solder provided by the present invention has very low O, N, and H contents and has very high cleanliness.

[0044] In some specific embodiments of the present invention, the silver solder comprises the following components by mass percentage:

[0045] Ag, Cu, Zn in fixed proportions 60%~75%, Hf 0.05%~0.5%, B 0.05%~0.3%, Cr, Zr in fixed proportions 0.5%~2%, and Ni as the balance.

[0046] Adding strong dehydrogenation elements Hf and strong deoxidation elements B to silver solder can remove hydrogen and oxygen from the solder, improve the cleanliness of the solder, reduce solder joint defects, and improve solder joint strength; at the same time, B can also significantly refine the solder grains, thereby further improving the solder joint strength.

[0047] In some embodiments, typically but not limiting, for example, the total mass percentage of Ag, Cu, and Zn in the silver solder can be any point value among 60%, 65%, 70%, 72%, and 75%, or a range value consisting of any two point values; the mass percentage of Hf can be any point value among 0.05%, 0.1%, 0.3%, and 0.5%, or a range value consisting of any two point values; the mass percentage of B can be any point value among 0.05%, 0.1%, 0.2%, and 0.3%, or a range value consisting of any two point values; the total mass percentage of Cr and Zr can be any point value among 0.5%, 1%, 1.5%, and 2%, or a range value consisting of any two point values.

[0048] In some specific embodiments of the present invention, the mass ratio of Ag, Zn and Cu is 25:35:40, that is, Zn:Cu=35:40, Ag:(Zn+Cu)=1:3, the purpose of which is to make the liquidus temperature of the ternary alloy the lowest and free of brittle phase. Specifically, when Zn:Cu=35:40, it is known from the binary phase of copper and zinc that at this time the alloy only contains the highly plastic α phase, and almost no brittle β phase, and the plastic processing property of the solder is good; when the mass ratio of silver to a certain ratio of Zn and Cu (Zn:Cu=35:40) is 1:3, it is known from the binary phase that at this time the liquidus temperature of the AgCuZn ternary alloy is the lowest, about 790℃, and Ni and other elements are added to this ternary alloy, the solder alloy obtained has the lowest liquidus and the best soldering processability.

[0049] In some specific embodiments of the present invention, the mass ratio of Cr and Zr in the silver solder is 1.5-2.5:1. For example, the mass ratio of Cr and Zr can be any point value among 1.5:1, 1.7:1, 2:1, 2.3:1, 2.5:1 or a range value consisting of any two point values.

[0050] The purpose of controlling the mass ratio of Cr to Zr between 1.5 and 2.5:1 is to make the molar ratio of Cr to Zr greater than 2:1, so that Cr2Zr can be formed and excess Cr can be precipitated as dispersed particles, forming dispersed solid solution strengthening particles Cr and Cr2Zr in the brazing seam, thereby improving the brazing seam strength. However, too much Cr will increase the brittleness of the brazing filler metal. Therefore, the mass ratio of Cr to Zr needs to be reasonably controlled.

[0051] In some specific embodiments of the present invention, the melting temperature of the silver solder is 700-790°C, for example, it can be any point value among 700°C, 720°C, 750°C, 770°C, 790°C, or a range value consisting of any two points.

[0052] In Ag solder, when the Ag content is between about 15-25% (melting temperature range is between about 700-790°C), adding Ni will significantly increase the liquidus temperature of the solder. For every 1% of Ni added, the liquidus temperature will increase by about 6°C. If it is added in a normal way, not only will it be difficult to add too much nickel evenly, but the liquidus temperature of the solder will also increase a lot (more than 20 nickels, the liquidus temperature of the solder will increase to 910°C). The present invention utilizes the alternating spacing of nickel layers and silver alloy layers or the uniform distribution of multiple nickel cores in the silver alloy portion. , avoiding Ni raising the liquidus line of the original solder; specifically, since the melting temperature of the silver alloy layer or the silver alloy portion is relatively low, the silver alloy layer outside the nickel layer or the silver alloy portion around the nickel core can be melted at a relatively low temperature, and since the single nickel layer is very thin and the single nickel core is very fine, it will dissolve in the surrounding silver alloy during the heating and melting process, and in-situ synthesize high-nickel silver solder, and the melting and welding of the high-nickel solder can be achieved at the melting temperature of the original silver alloy itself, thereby improving the feasibility of the brazing operation and avoiding thermal damage to the brazed parts.

[0053] A second aspect of the present invention provides a method for preparing the silver solder according to any one of the aforementioned embodiments, comprising the following steps:

[0054] S1. Calculate 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 percentage of each component;

[0055] S2. Determine the mold size, and calculate the total thickness of the plate-shaped brazing ingot and the thickness of a single nickel layer in the ingot, or the radius of the columnar brazing ingot and the radius of the nickel core in the ingot based on the mass of nickel, the mass of the remaining brazing metal, and the number of nickel layers or nickel cores;

[0056] S3. Obtain the corresponding number of nickel layers or nickel cores according to the size calculated in step S2;

[0057] S4. Coating the inner surface of the mold with graphite emulsion, and fixing the nickel layer or the nickel core at a suitable position in the mold cavity;

[0058] S5. Weigh the remaining components of the brazing filler metal in a mass ratio, smelt them into molten metal under an inert gas protection, and inject them into the mold cavity in step S4, and obtain a plate-shaped brazing filler ingot or a columnar brazing filler ingot after cooling and demolding;

[0059] S6. The plate-shaped solder ingot is subjected to multiple hot rolling processes to obtain a foil-shaped silver solder with a thickness of 0.1 to 0.5 mm; or, the columnar solder ingot is subjected to hot extrusion, rolling, and drawing to obtain a strip-shaped silver solder with a diameter of 1.5 to 3.0 mm.

[0060] The method of the present invention has a simple preparation process. A plurality of foil-like nickel layers or a plurality of strip-like nickel cores are fixed at intervals inside a mold cavity. A multi-layer plate-like solder ingot or a multi-nickel core columnar solder ingot is obtained by casting and demolding the remaining solder metal liquid. A foil-like silver solder or a strip-like silver solder with a high nickel content can be obtained by conventional processing methods. The nickel content can reach more than 20wt%, thereby solving the problem that the current high-nickel silver solder is brittle and difficult to process. In addition, the high-nickel silver solder can maintain a relatively low liquidus temperature, and the liquidus temperature will not be significantly increased due to an increase in the Ni content.

[0061] In step S4, the purpose of coating the inner surface of the mold with graphite emulsion is to purify the solder, and deoxidation can be performed at the moment of casting to improve the cleanliness of the solder.

[0062] In the ingot of step S5, the portion filled with the remaining brazing metal is the silver alloy layer or the silver alloy portion.

[0063] In some specific embodiments of the present invention, in step S1, the remaining solder metal refers to other raw materials in the silver solder except nickel, including Ag, Cu, Zn, Hf, B, Cr and Zr.

[0064] In some specific embodiments of the present invention, in step S2, the thickness of a single nickel layer in the plate-shaped solder ingot accounts for 1 / 15 to 1 / 7 of the total thickness of the ingot, for example, it can be any point value among 1 / 15, 1 / 14, 1 / 13, 1 / 12, 1 / 11, 1 / 10, 1 / 9, 1 / 8, 1 / 7, or a range value consisting of any two point values; and / or, the diameter of the nickel core in the columnar solder ingot accounts for 1 / 4 to 1 / 3 of the total diameter of the ingot, for example, it can be any point value among 1 / 4, 1 / 3.9, 1 / 3.7, 1 / 3.5, 1 / 3.2, 1 / 3, or a range value consisting of any two point values.

[0065] In some specific embodiments of the present invention, in step S3, the nickel layer or the nickel core can be made of purchased nickel foil or nickel wire, or can be obtained by smelting, casting, extrusion or rolling metal nickel.

[0066] In some specific embodiments of the present invention, in step S4, the nickel layer or the nickel core is fixed in the mold cavity by spot welding and is evenly distributed in the mold cavity.

[0067] In some specific embodiments of the present invention, in step S5, Cr in the remaining brazing filler metal is added in the form of Cu10Cr master alloy; and / or Zr is added in the form of Cu20Zr master alloy; adding in the form of alloy can achieve the purpose of precise addition.

[0068] In some specific embodiments of the present invention, in step S5, Hf in the remaining brazing filler metal is added in the form of Hf powder, and B is added in the form of B powder.

[0069] In some specific embodiments of the present invention, the particle sizes of Hf powder and B powder are both 0.05-0.25 mm, for example, the particle sizes of Hf powder and B powder can be any point value among 0.05 mm, 0.10 mm, 0.15 mm, 0.20 mm, and 0.25 mm, or a range of any two point values. Hf powder and B powder are getters and deoxidizers. Too large particle sizes of the two will lead to a decrease in specific surface area and a decrease in dehydrogenation and deoxidation effects. Therefore, the particle sizes of Hf and B need to be reasonably controlled.

[0070] In some specific embodiments of the present invention, Hf powder and B powder are added last in the form of copper foil coating, and degassing is usually carried out last. The final addition of Hf powder and B powder can play a significant role in dehydrogenation and deoxygenation. If they are directly added to the molten metal, they will float on the surface and be unevenly distributed, resulting in reduced dehydrogenation and dehydrogenation effects. The present invention adds them in the form of copper foil coating, which can make them sink into the interior of the molten metal, with more uniform distribution and better dehydrogenation and deoxygenation effects.

[0071] In some specific embodiments of the present invention, a step of homogenizing annealing the plate-shaped solder ingot or the columnar solder ingot is included between step S5 and step S6, and the annealing temperature is 450-580°C, for example, it can be any point value among 450°C, 480°C, 500°C, 530°C, 550°C, and 580°C, or a range value consisting of any two point values; the annealing time is 3-5h, for example, it can be any point value among 3h, 3.5h, 4h, 4.5h, and 5h, or a range value consisting of any two point values.

[0072] The following is a detailed description of some embodiments of the present invention in conjunction with specific examples. The raw materials used in the examples can be purchased from the market unless otherwise specified.

[0073] Example 1

[0074] A foil-like silver solder is prepared, which is composed of alternating nickel layers and silver alloy layers, wherein the outermost layer is a silver alloy layer and the number of nickel layers is 3.

[0075] Silver solder includes the following components by mass percentage:

[0076] The fixed ratio of Ag, Zn, Cu is 60%, Hf is 0.05%, B is 0.05%, the fixed ratio of Cr, Zr is 0.5%, and Ni is 39.4%; among them, Zn:Cu=35:40, Ag:(Cu+Zn)=1:3, calculated Ag is 15%, Cu is 24%, Zn is 21%; the mass ratio of Cr to Zr is 1.5:1, and the particle size of Hf powder and B powder is 0.05mm.

[0077] Preparation of silver solder foil:

[0078] S1. Determine the total mass of the brazing material to be 50 kg, calculate the mass of nickel to be 19.7 kg based on the mass ratio, and the mass of the remaining brazing material metal to be 30.3 kg;

[0079] S2. Determine the mold cavity size to be 500 mm long and 400 mm high, and the density of nickel to be 8.9 g / cm 3 The density of the remaining brazing metal is calculated to be 8.9 g / cm based on the density and mass of each element of the remaining brazing metal. 3 ;

[0080] According to the formula 50cm×40cm×L 镍 ×8.9g / cm 3 = 19700g Calculate the total thickness L of the nickel layer in the plate-shaped solder ingot 镍 The thickness of a single nickel layer is 11 mm. 镍 =L 镍 / 3 = 3.66 mm;

[0081] According to the formula 50cm×40cm×L 银 ×8.9g / cm 3 =30300gCalculate the total thickness L of the silver alloy layer in the plate-shaped solder ingot 银 17mm;

[0082] The total width of the required mold cavity is 28 mm;

[0083] S3. Weigh 19.7kg of pure nickel, smelt, cast and roll under inert gas to obtain a nickel foil 1500mm long, 400mm wide and 3.66mm thick, and cut into 3 nickel layers of 500mm×400mm×3.66mm;

[0084] S4. Open the two halves of the cast iron mold, apply a layer of graphite emulsion on the inner surface of the mold, and spot weld the three nickel layers prepared in step S3 evenly to the bottom of the mold cavity;

[0085] S5. Weigh the Ag, Cu, Zn, Hf, B, Cr and Zr raw materials in the remaining brazing metal according to the mass ratio, and melt them into molten metal by inert gas protection smelting. Among them, Cr and Zr are added in the form of Cu10Cr and Cu20Zr intermediate alloys respectively, and Hf powder and B powder are added last in the form of copper foil coating; inject the molten metal into the mold cavity, and obtain a multi-layer plate-shaped brazing ingot after cooling and demolding.

[0086] S6. The multilayer plate solder ingot is placed in a box-type resistance furnace, homogenized and annealed at 450°C for 5 hours, and hot-rolled for multiple times to obtain a foil-like silver solder with a thickness of 0.1 mm.

[0087] Example 2

[0088] A foil-like silver solder is prepared, which is composed of alternating nickel layers and silver alloy layers, wherein the outermost layer is a silver alloy layer and the number of nickel layers is 4.

[0089] Silver solder includes the following components by mass percentage:

[0090] Ag, Zn, Cu 65%, Ni 32.2%, Hf 0.5%, B 0.3%, Cr, Zr 2% in a fixed ratio; among them, Zn:Cu=35:40, Ag:(Cu+Zn)=1:3, calculated Ag 16.25%, Cu 26%, Zn 22.75%; the mass ratio of Cr to Zr is 2:1, and the particle size of B powder and Hf powder are both 0.25mm.

[0091] Preparation of silver solder foil:

[0092] S1. Determine the total mass of the brazing material to be 100 kg, calculate the mass of nickel to be 32.2 kg based on the mass ratio, and the mass of the remaining brazing metal to be 67.8 kg;

[0093] S2. Determine the mold cavity size to be 500 mm long and 400 mm high, and the density of nickel to be 8.9 g / cm 3 The density of the remaining brazing metal is calculated to be 8.9 g / cm based on the density and mass of each element of the remaining brazing metal. 3 ;

[0094] According to the formula 50cm×40cm×L 镍 ×8.9g / cm 3 =32200gCalculate the total thickness L of the nickel layer in the plate-shaped solder ingot 镍 The thickness of a single nickel layer is 18 mm. 镍 =L镍 / 4 = 4.5 mm;

[0095] According to the formula 50cm×40cm×L 银 ×8.9g / cm 3 = 67800g Calculate the total thickness L of the silver alloy layer in the plate-shaped solder ingot 银 38mm;

[0096] The total width of the required mold cavity is 56 mm;

[0097] S3 weighed 32.2kg of pure nickel, smelted, cast and rolled under inert gas protection to obtain a nickel foil 2000mm long, 400mm wide and 4.5mm thick, and cut into 4 nickel layers of 500mm×400mm×4.5mm;

[0098] S4. Open the two halves of the cast iron mold, apply a layer of graphite emulsion on the inner surface of the mold, and spot weld the four nickel layers prepared in step S3 evenly to the bottom of the mold cavity;

[0099] S5. Weigh the Ag, Cu, Zn, Hf, B, Cr and Zr raw materials in the remaining brazing metal according to the mass ratio, and melt them into molten metal by inert gas protection smelting. Among them, Cr and Zr are added in the form of Cu10Cr and Cu20Zr intermediate alloys respectively, and Hf powder and B powder are added last in the form of copper foil coating; inject the molten metal into the mold cavity, and obtain a multi-layer plate-shaped brazing ingot after cooling and demolding.

[0100] S6. The multilayer plate solder ingot is placed in a box-type resistance furnace, homogenized and annealed at 450°C for 4 hours, and hot-rolled for multiple times to obtain a foil-like silver solder with a thickness of 0.5 mm.

[0101] Example 3

[0102] A strip-shaped silver solder is prepared, which is composed of three nickel cores and a silver alloy part wrapped around the three nickel cores.

[0103] Silver solder includes the following components by mass percentage:

[0104] Ag, Zn, Cu 70%, Ni 29.4%, Hf 0.05%, B 0.05%, Cr, Zr 0.5% in a fixed ratio; among them, Zn:Cu=35:40, Ag:(Cu+Zn)=1:3, calculated Ag 17.5%, Cu 28%, Zn 24.5%; the mass ratio of Cr to Zr is 2.5:1, and the particle size of Hf powder and B powder is 0.05mm.

[0105] Preparation of silver solder strips:

[0106] S1. Determine the total mass of the brazing filler metal to be 10 kg. According to the mass ratio, the mass of nickel is calculated to be 2.94 kg, and the mass of the remaining brazing filler metal is 7.06 kg.

[0107] S2. Determine that the mold cavity is cylindrical, the height is 400 mm, and the density of nickel is 8.9 g / cm 3 The density of the remaining brazing metal is calculated to be 8.9 g / cm based on the density and mass of each element of the remaining brazing metal. 3 ;

[0108] According to the formula π×r 2 ×40cm×8.9g / cm 3 ×3=2940g, the radius r of the nickel core in the columnar solder ingot is calculated to be 9.4mm;

[0109] According to the formula (π×R 2 ×40cm-π×r 2 ×40cm×3)×8.9g / cm 3 =7060g, the total radius R of the columnar solder ingot is calculated to be 29.9mm;

[0110] The radius of the required mold cavity is 29.9 mm;

[0111] S3. Weigh 2.94 kg of pure nickel, smelt under inert gas, cast, extruded and drawn to obtain a nickel wire 1200 mm long and 9.4 mm in radius, and cut into 3 nickel cores 9.4 mm in radius and 400 mm in length;

[0112] S4. Open the two halves of the cast iron mold, apply a layer of graphite emulsion on the inner surface of the mold, and spot weld the three nickel cores prepared in step S3 evenly to the bottom of the mold cavity;

[0113] S5. Weigh the Ag, Cu, Zn, Hf, B, Cr and Zr raw materials in the remaining brazing metal according to the mass ratio, and melt them into molten metal by inert gas protection smelting. Among them, Cr and Zr are added in the form of Cu10Cr and Cu20Zr intermediate alloys respectively, and Hf powder and B powder are added last in the form of copper foil coating; inject the molten metal into the mold cavity, and obtain a multi-nickel core columnar brazing ingot after cooling and demolding.

[0114] S6. Place the multi-nickel core columnar solder ingot in a box-type resistance furnace, homogenize and anneal at 450°C for 5 hours, and obtain a strip-shaped silver solder with a diameter of 1.5 mm through extrusion and drawing.

[0115] Example 4

[0116] A strip-shaped silver solder is prepared, which is composed of four nickel cores and a silver alloy part wrapped around the four nickel cores.

[0117] Silver solder includes the following components by mass percentage:

[0118] Ag, Zn, Cu 72%, Ni 25.2%, Hf 0.5%, B 0.3% in fixed ratios, Cr, Zr 2% in fixed ratios; among them, Zn:Cu=35:40, Ag:(Cu+Zn)=1:3, calculated Ag 18%, Cu 28.8%, Zn 25.2%; among them, the mass ratio of Cr to Zr is 2:1, and the particle size of Hf powder and B powder is 0.25mm.

[0119] Preparation of silver solder strips:

[0120] S1. Determine the total mass of the brazing material to be 10 kg. According to the mass ratio, the mass of nickel is calculated to be 2.52 kg, and the mass of the remaining brazing metal is 7.48 kg.

[0121] S2. Determine that the mold cavity is cylindrical, the height is 400 mm, and the density of nickel is 8.9 g / cm 3 The density of the remaining brazing metal is calculated to be 8.9 g / cm based on the density and mass of each element of the remaining brazing metal. 3 ;

[0122] According to the formula π×r 2 ×40cm×8.9g / cm 3 ×4=2520g, the radius r of the nickel core in the columnar solder ingot is calculated to be 7.5mm;

[0123] According to the formula (π×R 2 ×40cm-π×r 2 ×40cm×4)×8.9g / cm 3 =7480g, the total radius R of the columnar solder ingot is calculated to be 30mm;

[0124] The radius of the required mold cavity is 30 mm;

[0125] S3. Weigh 2.52kg of pure nickel, smelt under inert gas, cast, extruded and drawn to obtain a nickel wire 1600mm long and 7.5mm in radius, and cut into 4 nickel cores 7.5mm in radius and 400mm in length;

[0126] S4. Open the two halves of the cast iron mold, apply a layer of graphite emulsion on the inner surface of the mold, and spot weld the four nickel cores prepared in step S3 evenly distributed and fixed at the bottom of the mold cavity;

[0127] S5. Weigh the Ag, Cu, Zn, Hf, B, Cr and Zr raw materials in the remaining brazing metal according to the mass ratio, and melt them into molten metal by inert gas protection smelting. Among them, Cr and Zr are added in the form of Cu10Cr and Cu20Zr intermediate alloys respectively, and Hf powder and B powder are added last in the form of copper foil coating; inject the molten metal into the mold cavity, and obtain a multi-nickel core columnar brazing ingot after cooling and demolding.

[0128] S6. Place the multi-nickel core columnar solder ingot in a box-type resistance furnace, homogenize and anneal at 580°C for 3 hours, and obtain a strip silver solder with a diameter of 3.0 mm through extrusion and drawing.

[0129] Example 5

[0130] A strip-shaped silver solder is prepared, which is composed of three nickel cores and a silver alloy part wrapped around the three nickel cores.

[0131] Silver solder includes the following components by mass percentage:

[0132] The fixed ratios of Ag, Zn, Cu are 75%, Ni is 23.1%, Hf is 0.3%, B is 0.1%, and the fixed ratios of Cr and Zr are 1.5%; among them, Ag is 18.75%, Cu is 30%, and Zn is 26.25%; the mass ratio of Cr to Zr is 2:1, and the particle size of Hf powder and B powder is 0.20mm.

[0133] Preparation of silver solder strips:

[0134] S1. Determine the total mass of the brazing material to be 10 kg. According to the mass ratio, the mass of nickel is calculated to be 2.31 kg, and the mass of the remaining brazing metal is 7.69 kg.

[0135] S2. Determine that the mold cavity is cylindrical, the height is 400 mm, and the density of nickel is 8.9 g / cm 3 The density of the remaining brazing metal is calculated to be 8.6 g / cm based on the density and mass of each element of the remaining brazing metal. 3 ;

[0136] According to the formula π×r 2 ×40cm×8.9g / cm 3 ×3=2310g, the radius r of the nickel core in the columnar solder ingot is calculated to be 8.3mm;

[0137] According to the formula (π×R 2 ×40cm-π×r 2 ×40cm×3)×8.6g / cm 3 =7690g, the total radius R of the columnar solder ingot is calculated to be 30mm;

[0138] The radius of the required mold cavity is 30 mm;

[0139] S3. Weigh 2.31kg of pure nickel, smelt under inert gas, cast, extruded and drawn to obtain a nickel wire 1200mm long and 8.3mm in radius, and cut into 3 nickel cores 8.3mm in radius and 400mm in length;

[0140] S4. Open the two halves of the cast iron mold, apply a layer of graphite emulsion on the inner surface of the mold, and spot weld the three nickel cores prepared in step S3 evenly to the bottom of the mold cavity;

[0141] S5. Weigh the Ag, Cu, Zn, Hf, B, Cr and Zr raw materials in the remaining brazing metal according to the mass ratio, and melt them into molten metal by inert gas protection smelting. Among them, Cr and Zr are added in the form of Cu10Cr and Cu20Zr intermediate alloys respectively, and Hf powder and B powder are added last in the form of copper foil coating; inject the molten metal into the mold cavity, and obtain a multi-nickel core columnar brazing ingot after cooling and demolding.

[0142] S6. Place the multi-nickel core columnar solder ingot in a box-type resistance furnace, homogenize and anneal at 530°C for 4.5 hours, and obtain a strip-shaped silver solder with a diameter of 2.5 mm through extrusion and drawing.

[0143] Comparative Example 1

[0144] The composition of the silver solder is exactly the same as that in Example 1, except that Ni is added in a conventional form. All the raw materials are mixed and smelted by a conventional method, cast into an ingot (the mold is not coated with graphite emulsion), and then made into a foil solder by hot rolling. Due to the high nickel content, most of the nickel is precipitated during smelting and cannot be dissolved in the solder alloy. In addition, the solder is very brittle, and only a 1 mm thick foil solder can be obtained, and a 0.1 mm thick foil solder cannot be obtained.

[0145] Comparative Example 2

[0146] The difference between Comparative Example 2 and Example 1 is that Cr and Zr are not added to the component formula, and the other conditions are the same as Example 1.

[0147] Comparative Example 3

[0148] The difference between Comparative Example 3 and Example 1 is that no graphite emulsion is coated in the mold, and the other conditions are the same as Example 1.

[0149] Comparative Example 4

[0150] The difference between Comparative Example 4 and Example 1 is that the mass ratio of Cr to Zr is 1:1, and the other conditions are the same as Example 1.

[0151] Comparative Example 5

[0152] The difference between Comparative Example 5 and Example 1 is that Hf powder and B powder are first added in the form of copper foil coating, and the other conditions are the same as Example 1.

[0153] Comparative Example 6

[0154] The difference between Comparative Example 6 and Example 1 is that the mass ratio of Cr to Zr is 4:1, and the other conditions are the same as Example 1.

[0155] Comparative Example 7

[0156] The difference between Comparative Example 7 and Example 1 is that the particle sizes of Hf powder and B powder are both greater than 0.25 mm, and the other conditions are the same as Example 1.

[0157] Comparative Example 8

[0158] The difference between Comparative Example 8 and Example 1 is that Hf and B are not added, and the other conditions are the same as Example 1.

[0159] Comparative Example 9

[0160] The silver solder formula composition in Comparative Example 9 is the same as that in Example 3, except that Ni is added in a conventional form, and all raw materials are mixed and smelted by a conventional method, cast into an ingot (the mold is not coated with graphite emulsion), and then made into a strip solder by hot extrusion and drawing. Due to the high nickel content, the nickel cannot be completely melted into the alloy during smelting, and the solder is brittle and can only be drawn into a strip solder with a diameter of 10 mm, and a strip solder with a diameter of ≤3 mm cannot be obtained.

[0161] Comparative Example 10

[0162] The difference between Comparative Example 10 and Example 1 is that the mass ratio of Ag, Cu and Zn is different, in which Zn:Cu=1:1, Ag:(Zn+Cu)=1:3, and the rest is exactly the same as Example 1. The Zn content in the solder alloy is high, the β brittle phase increases, and the processing performance is deteriorated.

[0163] Comparative Example 11

[0164] Traditional silver solder, Ag: Zn: Cu ≠ 25: 35: 40, by mass percentage, the silver solder in comparative example 11 includes: Ag 20%, Zn 25%, Ni 2%, Hf 0.05%, B 0.05%, Cr and Zr 0.5% in a certain ratio, and the balance of copper; wherein the mass ratio of Cr to Zr is 2: 1. Using the traditional method, all raw materials are induction smelted in the atmosphere to obtain molten metal, which is injected into a mold without graphite emulsion coating, and a single-layer plate-shaped solder ingot is obtained after cooling and demolding. After annealing, it is hot-rolled for multiple passes to obtain a foil-shaped silver solder with a thickness of 0.1 mm. The other parameter conditions are the same as those in Example 1. The liquidus temperature of the obtained solder is higher than 900°C, and it is easy to cause thermal damage to the weldment base material without welding.

[0165] Test Example 1

[0166] In order to investigate the brazing performance of the silver solder in each embodiment of the present invention and each comparative example, the silver solder in each embodiment and each comparative example was used to braze YG6X cemented carbide and 65Mn steel, respectively. Induction brazing was adopted. The brazing temperature of Embodiments 1-5, Comparative Examples 2-8 and Comparative Example 10 was 820-840°C. The brazing temperature of Comparative Examples 1, 9 and 11 was 930-950°C due to the high liquidus temperature of the solder. The holding time was 5 min. 20 specimens were welded, and the shear strength of the joint was tested. The average value was taken. The test results are shown in Table 1.

[0167] Table 1

[0168]

[0169] It can be seen from the data in Table 1 that the joint strength of the soldered joints in the embodiment is much higher than that in the comparative example. In particular, the shear strength of the joints brazed with solder in Example 2 is as high as 355.3 MPa, which is about 64% higher than the shear strength of the joints brazed with traditional silver solder 216.4 MPa (Comparative Example 11).

[0170] Test Example 2

[0171] In order to investigate the cleanliness of the silver solder in each embodiment and each comparative example, each solder was subjected to nitrogen, hydrogen and oxygen tests. Each sample was tested 3 times and the average value was taken. The test results are shown in Table 2.

[0172] Table 2

[0173] Brazing material type O content / ppm N content / ppm H content / ppm Silver solder in Example 1 22.4 7.2 3.7 Silver solder in Example 2 20.5 6.8 3.6 Silver solder in Example 3 21.6 7.0 3.8 Silver solder in Example 4 20.8 6.6 3.5 Silver solder in Example 5 20.3 6.9 3.6 Comparative Example 1 Silver solder 50.5 15.2 7.2 Comparative Example 2 Silver solder 23.1 7.3 3.6 Comparative Example 3 Silver solder 45.8 14.8 6.7 Comparative Example 4: Silver solder 23.4 7.5 3.8 Comparative Example 5 Silver solder 60.5 21.4 10.8 Comparative Example 6 Silver solder 22.1 7.9 3.8 Comparative Example 7 Silver solder 30.5 8.7 5.6 Comparative Example 8 Silver solder 80.1 28.3 15.2 Comparative Example 9 Silver solder 46.2 14.3 6.5 Comparative Example 10 Silver solder 24.3 8.0 3.8 Comparative Example 11 Silver solder 780 206 35.8

[0174] It can be seen from the data in Table 1 that the O, N, and H contents of the silver solders in Examples 1-5 are relatively low. Compared with the traditional silver solder (Comparative Example 11), the oxygen content is reduced from hundreds of ppm to tens of ppm, and the gas impurity content in the solder is significantly reduced.

[0175] Depend on Figure 2 and Figure 3 It can be seen that the cemented carbide tool brazed with silver solder in Example 1 has better quality, while the cemented carbide tool brazed with silver solder in Comparative Example 1 has more pores on the weld surface, which affects the service life of the tool.

[0176] Although the present invention has been illustrated and described with specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents without departing from the spirit and scope of the present invention. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A silver solder, characterized in that: The solder of the silver solder is in the form of a foil containing a plurality of nickel layers or a strip containing a plurality of nickel cores; The foil-like silver solder comprises a plurality of the nickel layers and a plurality of silver alloy layers, wherein the nickel layers and the silver alloy layers are arranged alternately, and the outermost layer is the silver alloy layer; The strip-shaped silver solder comprises a plurality of nickel cores and a silver alloy portion wrapped around the outer sides of the plurality of nickel cores.

2. The silver solder according to claim 1, characterized in that: In the foil-like silver solder, there is a metallurgical reaction bonding layer between the nickel layer and the silver alloy layer, and the number of the nickel layers is ≥3; and / or, in the strip-like silver solder, there is a metallurgical reaction bonding layer between the nickel core and the silver alloy part, and the number of the nickel cores is ≥3.

3. The silver solder according to claim 1, characterized in that: Contains at least one of the following characteristics: (1) The thickness of the foil-like silver solder is 0.1 to 0.5 mm; (2) In the foil-like silver solder, the thickness of the single nickel layer accounts for 1 / 15 to 1 / 7 of the total thickness of the foil-like silver solder; (3) The diameter of the strip silver solder is 1.5 to 3.0 mm; (4) In the strip-shaped silver solder, the diameter of the nickel core accounts for 1 / 4 to 1 / 3 of the total diameter of the strip-shaped silver solder.

4. The silver solder according to claim 1, characterized in that: The Ni content in the silver solder is higher than 20%; And / or, the O content in the silver solder is less than 25 ppm, the N content is less than 7.5 ppm, and the H content is less than 4 ppm.

5. The silver solder according to claim 1, characterized in that: The silver solder comprises the following components by mass percentage: Ag, Cu, Zn in fixed proportions 60%~75%, Hf 0.05%~0.5%, B 0.05%~0.3%, Cr, Zr in fixed proportions 0.5%~2%, and Ni as the balance.

6. The silver solder according to claim 5, characterized in that: Meet at least one of the following characteristics: (1) The mass ratio of Ag, Zn and Cu is 25:35:40; (2) The mass ratio of the Cr to the Zr is 1.5 to 2.5:

1.

7. The silver solder according to claim 5, characterized in that: The melting temperature of the silver solder is 700-790°C.

8. The method for preparing the silver solder according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Calculate 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 percentage of each component; S2. Determine the mold size, calculate the total thickness of the plate-shaped brazing ingot and the thickness of a single nickel layer in the ingot, or the radius of the columnar brazing ingot and the radius of the nickel core in the ingot according to the mass of the nickel, the mass of the remaining brazing metal, and the number of nickel layers or nickel cores; S3. According to the size calculated in step S2, obtaining a corresponding number of the nickel layer or the nickel core; S4. Coating graphite emulsion on the inner surface of the mold, fixing the nickel layer or the nickel core interval in the mold cavity; S5. Weigh the components of the remaining brazing filler metal according to the mass ratio, smelt them into molten metal under the protection of inert gas, and inject them into the mold cavity in step S4, and obtain the plate-shaped brazing filler ingot or the columnar brazing filler ingot after cooling and demolding; S6. Hot-rolling the plate-shaped solder ingot to obtain foil-shaped silver solder; or hot-extruding, rolling, and drawing the columnar solder ingot to obtain strip-shaped silver solder.

9. The method for preparing the silver solder according to claim 8, characterized in that: In step S5, Cr in the remaining brazing filler metal is added in the form of Cu10Cr master alloy; and / or Zr is added in the form of Cu20Zr master alloy.

10. The method for preparing the silver solder according to claim 8, characterized in that: In step S5, Hf and B in the remaining brazing filler metal are added in the form of Hf powder and B powder, and meet at least one of the following characteristics: (1) The particle sizes of the Hf powder and the B powder are both 0.05 to 0.25 mm; (2) The Hf powder and the B powder are both added last in the form of copper foil coating.

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