A preparation method of a metal welding material

Abstract

The present invention belongs to the technical field of welding materials and relates to a preparation method of a metal welding material. The present invention aims to solve the problem that it is difficult to balance the wettability and thermal conductivity of existing brazing materials with respect to the base material. In the present invention, a ternary nanoparticle is prepared by solvothermal treatment of a metal precursor solution and dispersed in a soldering flux to obtain a wire core material; copper, tin, and nickel are prepared into a nickel bronze alloy, which is then drawn into a nickel bronze hollow wire; the wire core material is filled into the nickel bronze hollow wire, and after encapsulation treatment, a metal welding material is obtained. The metal welding material prepared by the present invention has excellent wettability as a brazing material, forms a solder layer with high strength and high thermal conductivity, and has significant application value in the field of electronic device welding.

Description

Technical Field

[0001] The present invention belongs to the technical field of welding materials and relates to a preparation method of a metal welding material. Background Art

[0002] Human beings have been using metal materials for a long time, and welding technology is an important processing technology for the application of metal materials. The earliest welding technology was simply to connect high-temperature metals together by forging, without the need for additional welding materials. Since modern times, with the rise of the industrial revolution, the metal processing industry has had higher and higher requirements for welding technology and welding materials. Along with the continuous improvement of welding technology, welding materials have developed rapidly. Modern welding materials are mainly divided into types such as welding rods, welding wires, and solder pastes, and are widely used in fields such as mechanical manufacturing, the electronics industry, and chemical engineering. With the development of emerging industries and the industrial upgrading of traditional industries, people's requirements for the functionality and performance of new welding materials are also getting higher and higher.

[0003] In particular, in the field of the electronics industry, brazing, as a common welding process, has been favored by more and more production links because of its precise and stable characteristics. With the development of electronic technology, the increase in miniaturized devices has made brazing the preferred process for high-performance connections in the electronics industry. Currently, the main materials for manufacturing electronic devices in industry include metals, ceramics, semiconductor materials, etc., and the brazing materials for effectively connecting these materials are the focus of research and improvement in the current academic and industrial circles.

[0004] For example, Chinese Patent CN108136548B provides a brazing alloy mainly containing copper, silver, zinc, manganese, and indium, which has a low silver content and a low melting point, and does not affect its cold working performance and connection strength. The problem with this invention is that it can effectively weld ceramic materials and steel materials, but the welding effect on other dissimilar materials has not been verified. Chinese Patent CN108296671B proposes a composite silver solder paste and its preparation method, which has the characteristics of high electrical and thermal conductivity and high strength. The solder paste product has good fluidity and strong gap filling ability. The main problem with this invention is that although the welding strength is high, the thermal conductivity is not improved compared with traditional brazing materials. Chinese Patent CN114850729B proposes a cadmium-free silver brazing material, which can achieve reliable interconnection of metal-metal in electrical equipment, and uses the multi-coupling effect of inorganic nanowires and inorganic sub-micron particles to improve the mechanical properties and reliability of the weld. The problem with this invention is that it is only optimized for metal-metal interconnection, and the performance such as thermal conductivity has not been verified.

[0005] Currently, it is still an important problem faced by the industry that it is difficult to balance the wettability and thermal conductivity of existing brazing materials with respect to the base material.

[0006] Therefore, a method for preparing metal welding materials is proposed. Summary of the invention

[0007] The purpose of the present invention is to provide a method for preparing a metal welding material. The present invention aims to solve the problem that existing brazing materials are difficult to balance the wettability and thermal conductivity of the base material. The present invention prepares a metal precursor solution into ternary nanoparticles through solvent thermal treatment, and disperses the particles in a flux to prepare a welding wire core material; prepares copper, tin, and nickel into a nickel bronze alloy, and then draws it into a nickel bronze hollow wire; fills the welding wire core material into the nickel bronze hollow wire, and obtains the metal welding material after packaging. The metal welding material prepared by the present invention has excellent wettability as a brazing material, and the formed welding layer has high strength and high thermal conductivity, and has significant application value in the field of electronic device welding.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A method for preparing a metal welding material comprises the following steps:

[0010] 100 parts of metal precursor solution, 2-4 parts of reducing agent and 2-3 parts of surfactant were mixed and added to a hydrothermal autoclave. The mixture was preheated at 200°C for 30 minutes, heated to 300°C and reacted under the autogenous pressure of the hydrothermal autoclave for 12 hours. The mixture was cooled to 25°C and centrifuged at 6000-8000 rpm for 10 minutes to obtain a solid product. The solid product was washed with ethanol and deionized water and vacuum dried at 60°C for 24 hours to obtain ternary nanoparticles.

[0011] Copper powder, tin powder and nickel powder are put into an induction furnace in a mass ratio of 4:3:1, heated to 600°C and preheated for 20 minutes, then heated to 1200-1300°C at a heating rate of 200°C / min. After ensuring that the raw materials are completely melted, heating is continued for 4-6 hours, and nitrogen is blown in for degassing to obtain a molten alloy; the molten alloy is poured into a tubular mold and cooled to form an alloy tube; the alloy tube is reheated to 500-550°C for annealing, kept warm for 8-12 hours, and then cooled to 25°C at a rate of 5°C / min to obtain a nickel bronze alloy.

[0012] The nickel bronze alloy is heated to 550-600°C and kept warm for 30 minutes, and is drawn multiple times using a drawing machine until the diameter of the nickel bronze alloy is less than 1 mm to obtain a hollow wire precursor; the hollow wire precursor is cooled to 400°C at a rate of 5°C / min, kept warm for 4 hours, and then cooled to 25°C at a rate of 25°C / min to obtain a nickel bronze hollow wire.

[0013] 200 parts of the ternary nanoparticles were mixed with 200 parts of flux at 120° C. to obtain a welding wire core material.

[0014] Preheat the wire core material and the nickel - bronze hollow wire to 120 °C and keep the operating temperature unchanged. Subsequently, inject the wire core material into the cavity of the nickel - bronze hollow wire using a syringe to obtain a precursor of the welding material. Spot - weld the two ends of the precursor of the welding material. After sealing the two ends of the precursor of the welding material, perform ultrasonic treatment at a frequency of 50 kHz at 50 °C for 2 hours and then cool it to 25 °C at a rate of 10 °C / min to obtain the metal welding material.

[0015] Preferably, the metal precursor solution includes: silver nitrate, indium acetate, zinc acetate and ethylene glycol. Among them, the concentration of silver nitrate is 1.5 mol / L, the concentration of indium acetate is 0.3 mol / L, and the concentration of zinc acetate is 1.0 mol / L.

[0016] Preferably, the reducing agent includes: sodium citrate and sodium ascorbate. Among them, the mass ratio of sodium citrate to sodium ascorbate is 1:2.

[0017] Preferably, the surfactant includes: polyvinyl alcohol and cetyltrimethylammonium bromide. Among them, the mass ratio of polyvinyl alcohol to cetyltrimethylammonium bromide is 5:1.

[0018] Preferably, the addition amount of the ternary nanoparticles is 200 parts; the flux is rosin, and its addition amount is 200 parts.

[0019] Preferably, the injection speed is the filling speed of the wire core material in the nickel - bronze hollow wire. Among them, the injection speed is 5 cm / min.

[0020] The metal welding material prepared by the present invention belongs to silver - based brazing materials.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. Prepare silver, indium and zinc into ternary nanoparticles through solvothermal treatment. During the brazing process, a low - melting - point eutectic phase can be formed, effectively reducing the melting point of the brazing material and improving the usability of the metal welding material. At the same time, the presence of the nano - alloy particles can effectively reduce the surface energy between the brazing material and the base metal to be welded, improving the spreading property of the metal welding material on the surface of the base metal, that is, improving the wettability of the metal welding material to various different materials.

[0023] 2. Use copper, tin and nickel to prepare a hollow nickel - bronze alloy wire through alloying and tube - forming processes. The interaction of the three metal atoms effectively reduces the melting point of the metal welding material. And due to its hollow structure, the specific surface area of the welding material is larger and the overall melting process is shorter, actually reducing the operating temperature during the welding process. In particular, nickel and tin elements have high wettability on the surface of most metal base metals, expanding the range of base metals suitable for the metal welding material.

[0024] 3. By pre-mixing ternary nanoparticles with a soldering flux, the dispersibility of the nanoparticles is improved, the agglomeration phenomenon of the ternary nanoparticles during subsequent processing is significantly reduced, the interfacial thermal resistance between the nanoparticles and the base material is effectively reduced during the welding process, and the thermal conductivity of the metal welding material is increased. Moreover, the pre-introduction of the soldering flux helps to improve the heat conduction effect of the entire welding process, improve the uniformity of the welding layer, and build a three-dimensional heat conduction network with the nanoparticles as nodes, without the need for additional addition of the soldering flux, which has significant application value in the welding process of precision components.

[0025] 4. Filling the wire core material into the nickel bronze hollow wire fully combines the characteristics of the two different materials, and it can have excellent wettability and a low melting point at different stages of welding. Its synergistic effect significantly improves the heat distribution of the metal welding material during the entire welding process, making the welding layer more uniform and dense. The good co-melting of the wire core material and the nickel bronze hollow wire during the welding process can effectively reduce the welding stress generated due to the difference in the coefficient of thermal expansion between the weld and the base material, and improve the stability of the welded structure.

[0026] 5. Through the encapsulation treatment of the welding material precursor, the ternary nanoparticles are effectively dispersed on the inner surface of the nickel bronze hollow wire, effectively improving the fluidity of the molten welding material during the welding process and enhancing the wettability of the metal welding material to the welding base material. The ultrasonic process in the encapsulation treatment can also effectively reduce the pores and microcracks and other structures inside the metal welding material, improving the thermal conductivity of the metal welding material. The weld formed by the welding material with fewer defects is more uniform. These two effects together enable the weld formed by the metal welding material to have excellent thermal conductivity and be suitable for fields such as the welding of precision electronic components. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a process flow chart of the preparation method of the metal welding material in the present invention.

[0028] Figure 2 It is a schematic structural diagram of the metal welding material prepared by the present invention.

[0029] In the figure, 1 is the nickel bronze hollow wire; 2 is the wire core material. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The technical solutions of the present invention will be clearly and completely described below through some examples and experimental examples. Obviously, the described examples are only a part of the examples of the present invention, rather than all the examples. All other examples obtained by those of ordinary skill in the art based on the examples of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0031] Refer to Figure 1The present invention provides a method for preparing a metal welding material, and the technical solution is as follows:

[0032] The substance information involved in the present invention is as follows:

[0033] Silver nitrate: CAS: 7761-88-8; Indium acetate: CAS: 25114-58-3; Zinc acetate: CAS: 557-34-6; Ethylene glycol: CAS: 107-21-1; Sodium citrate: CAS: 68-04-2; Rosin: CAS: 8050-09-7; Copper powder: CAS: 7440-50-8; Tin powder: CAS: 7440-31-5; Nickel powder: CAS: 7440-02-0; Sodium ascorbate: CAS: 134-03-2; Ethanol: CAS: 64-17-5.

[0034] Example 1

[0035] 100 parts of metal precursor solution, 2 parts of reducing agent and 2 parts of surfactant were mixed and added to a hydrothermal autoclave. The mixture was preheated at 200°C for 30 minutes, heated to 300°C and reacted under the autogenous pressure of the hydrothermal autoclave for 12 hours. The mixture was cooled to 25°C and centrifuged at 6000 rpm for 10 minutes to obtain a solid product. The solid product was washed with ethanol and deionized water and vacuum dried at 60°C for 24 hours to obtain ternary nanoparticles.

[0036] The metal precursor solution includes: silver nitrate, indium acetate, zinc acetate and ethylene glycol, wherein the concentration of silver nitrate is 1.5 mol / L, the concentration of indium acetate is 0.3 mol / L, and the concentration of zinc acetate is 1.0 mol / L; the reducing agent includes: sodium citrate and sodium ascorbate, wherein the mass ratio of sodium citrate to sodium ascorbate is 1:2; the surfactant includes: polyvinyl alcohol and hexadecyltrimethylammonium bromide, wherein the mass ratio of polyvinyl alcohol to hexadecyltrimethylammonium bromide is 5:1.

[0037] Copper powder, tin powder and nickel powder are placed in an induction furnace in a mass ratio of 4:3:1. The temperature is raised to 600°C and preheated for 20 minutes. The temperature is then raised to 1200°C at a heating rate of 200°C / min. After ensuring that the raw materials are completely melted, heating is continued for 4 hours, and nitrogen is blown in for degassing to obtain a molten alloy. The molten alloy is poured into a tubular mold and cooled to form an alloy tube. The alloy tube is reheated to 500°C for annealing, kept at this temperature for 8 hours, and then cooled to 25°C at a rate of 5°C / min to obtain a nickel bronze alloy.

[0038] Heat the nickel bronze alloy to 550 °C and hold for 30 min, then perform multiple drawing operations using a drawing machine until the diameter of the nickel bronze alloy is less than 1 mm to obtain a hollow wire precursor; cool the hollow wire precursor to 400 °C at a rate of 5 °C / min, hold for 4 hours, and then cool to 25 °C at a rate of 25 °C / min to obtain nickel bronze hollow wire 1.

[0039] Mix 200 parts of ternary nanoparticles with 200 parts of rosin at 120 °C to obtain welding wire core material 2.

[0040] Preheat welding wire core material 2 and nickel bronze hollow wire 1 to 120 °C and keep the operating temperature unchanged. Then, inject welding wire core material 2 into the cavity of nickel bronze hollow wire 1 using a syringe to obtain a precursor of the welding material. Here, the injection speed is the filling speed of the welding wire core material in the nickel bronze hollow wire, and the injection speed is 5 cm / min; spot-weld the two ends of the precursor of the welding material, close the two ends of the precursor of the welding material, and then perform ultrasonic treatment at 50 °C with an ultrasonic frequency of 50 kHz for 2 hours and then cool to 25 °C at a rate of 10 °C / min to obtain the metal welding material.

[0041] As Figure 2 shown in the schematic diagram of the structure of the metal welding material, the metal welding material prepared by the present invention is composed of nickel bronze hollow wire 1 and welding wire core material 2, and welding wire core material 2 is filled in the cavity of nickel bronze hollow wire 1.

[0042] Examples 2 - 20 have parameter adjustments compared to Example 1, and the specific summaries are shown in Table 1.

[0043] Table 1 Process parameter adjustments for Examples 1 - 20

[0044]

[0045] Comparative Example 1

[0046] Different from Example 1, no solvothermal treatment is performed, and an equimolar mixture of silver, indium, and zinc elemental powders is used to replace the ternary nanoparticles, where the molar ratio of silver, indium, and zinc is 15:3:10, and other process parameters are the same.

[0047] Comparative Example 2

[0048] Different from Example 1, silver nitrate is not added to the metal precursor solution, and other process parameters are the same.

[0049] Comparative Example 3

[0050] Different from Example 1, indium acetate is not added to the metal precursor solution, and other process parameters are the same.

[0051] Comparative Example 4

[0052] The difference from Example 1 is that zinc acetate is not added to the metal precursor solution, and other process parameters are the same.

[0053] Comparative Example 5

[0054] Different from Example 6, no copper is added during the alloying process, and other process parameters are the same.

[0055] Comparative Example 6

[0056] The difference from Example 6 is that no tin is added during the alloying process, and other process parameters are the same.

[0057] Comparative Example 7

[0058] Different from Example 6, nickel was not added during the alloying process, and other process parameters were the same.

[0059] Comparative Example 8

[0060] Different from Example 10, the tube forming process is not performed, and the nickel bronze alloy and the welding wire core material 2 are mixed and used during the welding process. Other process parameters are the same.

[0061] Comparative Example 9

[0062] Different from Example 10, the ternary nanoparticles and the flux are not pre-mixed, and the ternary nanoparticles, the flux and the nickel bronze alloy wire are mixed for use, and the other process parameters are the same.

[0063] Comparative Example 10

[0064] The difference from Example 15 is that the welding material precursor is not packaged, and only the two ends of the welding material precursor are sealed by spot welding. Other process parameters are the same.

[0065] Comparative Example 11

[0066] The difference from Example 15 is that during the packaging process, only heating to 50° C. is performed, and ultrasonic treatment is not performed. Other process parameters are the same.

[0067] Experimental Example 1

[0068] Differential scanning calorimetry (DSC) was used to measure the melting points of the metal welding materials prepared in Examples 1-5 and Comparative Examples 1-4, respectively. The temperature corresponding to the peak value of the maximum endothermic peak was taken as the melting point of the metal welding material. The relevant data are summarized in Table 2.

[0069] The static wetting angles of the metal welding materials prepared in Examples 1-5 and Comparative Examples 1-4 were measured. The static wetting angles of the different metal welding materials on the surfaces of nickel base material, copper base material, carbon steel base material, and stainless steel base material after melting were measured. The relevant data are summarized in Table 2.

[0070] The melting point of the brazing material should not be too high or too low. If the melting point is too high, the temperature during the welding process will be high, which will cause irreversible damage to precision equipment such as electronic components. If the melting point is too low, there may be a situation of desoldering during use if the device heats up after welding is completed.

[0071] Table 2 Melting points and contact angles of different metal solders prepared in Examples 1-5 and Comparative Examples 1-4

[0072]

[0073] As shown in the melting point and contact angle data in Table 2, the melting points of the metal solders prepared in Examples 1-5 change very little, having a relatively stable melting point range, with a moderate temperature, being easy to melt during the brazing process and not prone to desoldering during use. For Comparative Example 1, due to the absence of nanoparticles, the melting point of the metal solder increases, and the wettability for various metal base materials decreases, which proves the important role of the ternary nanoparticles in the solder. For Comparative Example 2, the absence of silver element makes the melting point of the metal solder decrease. Due to the particularity of the brazing material, this melting point temperature can also meet the requirements, but its wettability for nickel, carbon steel, and stainless steel shows a significant decrease. For Comparative Example 3, the absence of indium element makes the melting point of the metal solder rise, and the wettability for various base materials also decreases, which represents that the indium element is a key component to reduce the melting point of the solder and improve the compatibility between the solder and the metal base material. For Comparative Example 4, the absence of zinc element increases the melting point of the metal solder and significantly reduces its wettability for carbon steel and stainless steel. In summary, the ternary nanoparticles prepared by the solvothermal method can effectively reduce the surface energy between the brazing material and the base material to be welded, improve the spreadability of the metal solder on the surface of the base material, that is, improve the wettability of the metal solder for various different materials, and at the same time reduce the melting point of the metal solder by forming a eutectic phase with a low melting point.

[0074] Experimental Example 2

[0075] Referring to the experimental methods and steps in Experimental Example 1, measure the melting points of the metal solders prepared in Experimental Examples 6-9 and Comparative Examples 5-7, as well as the static wetting angles on the surfaces of nickel base material, copper base material, carbon steel base material, and stainless steel base material. The obtained data are summarized in Table 3.

[0076] Referring to the experimental methods and steps in Experimental Example 1, measure the melting points of the metal solders prepared in Experimental Examples 10-14 and Comparative Example 8, as well as the static wetting angles on the surfaces of nickel base material, copper base material, carbon steel base material, and stainless steel base material. The obtained data are summarized in Table 3.

[0077] Table 3 Melting points and contact angles of different metal solders

[0078]

[0079] As shown in the melting point and contact angle data of different metal welding materials in Table 3, the metal welding materials prepared in Examples 6-9 and Examples 10-14 all have melting points within a stable range and good wettability. For Comparative Examples 5-7, the absence of different alloying elements resulted in a decrease in the wettability of the metal welding materials for different base materials, and to a certain extent, affected the melting point of the welding materials. Specifically, the absence of copper and tin elements would increase the melting point of the welding materials, while the absence of nickel element would increase the melting point of the welding materials. The alloying process and the pipe forming process combined the different characteristics of the three metal elements, making the prepared metal welding materials have good wettability for various base materials and stable melting points. The data of Comparative Example 8 showed that the pipe forming process could not directly reduce the melting point of the material. Its main function was to shorten the overall melting process and reduce the damage to the base material caused by overheating.

[0080] Experimental Example 3

[0081] The metal welding materials prepared in Examples 10-14 and Comparative Examples 8-9 were used to weld 0.5 mm nickel-copper welds respectively, and their thermal conductivities were measured.

[0082] Among them, the measurement method of the thermal conductivity was as follows: temperature sensors were set at both ends of the weld sample, the nickel-side base material of the weld was heated to make the temperature difference between the sensors at both ends of the weld 100 °C and kept stable. A heat flux meter was used to measure the steady-state heat flux density q passing through the sample, and the thermal conductivity of the weld was calculated by k = qL / AΔT. Among them, L was the sample thickness, A was the sample cross-sectional area, and ΔT was the temperature difference between the two sides.

[0083] Example 10: Thermal conductivity k = 172 W / m·K;

[0084] Example 11: Thermal conductivity k = 177 W / m·K;

[0085] Example 12: Thermal conductivity k = 179 W / m·K;

[0086] Example 13: Thermal conductivity k = 170 W / m·K;

[0087] Example 14: Thermal conductivity k = 173 W / m·K;

[0088] Comparative Example 8: Thermal conductivity k = 144 W / m·K;

[0089] Comparative Example 9: Thermal conductivity k = 120 W / m·K;

[0090] According to the thermal conductivity data of the metal welding materials prepared in Examples 10-14 and Comparative Examples 8-9 measured in Example 3, it can be seen that the metal welding materials prepared in Examples 10-14 have a higher thermal conductivity among silver-based brazing materials. For Comparative Example 8, due to the lack of a tube forming process, the metal welding material does not have a composite structure of a hollow tube and a filler, so the uniformity of the resulting weld decreases, the nanoparticles are directly heated to agglomerate and sinter, and the overall thermal conductivity is significantly reduced. For Comparative Example 9, the ternary nanoparticles are not pre-distributed in the flux, and the loss of thermal conductivity is greater than that of Comparative Example 8. In summary, the pre-mixing of the ternary nanoparticles with the flux effectively improves the dispersibility of the nanoparticles, significantly reduces the agglomeration of the ternary nanoparticles during subsequent processing, effectively reduces the interfacial thermal resistance between the nanoparticles and the base material during the welding process, improves the uniformity of the weld layer, and uses the nanoparticles as nodes to build a three-dimensional thermal conductive network, thereby improving the thermal conductivity of the metal welding material.

[0091] Experimental Example 4

[0092] 0.5 mm nickel-copper welds were welded using the metal welding materials prepared in Examples 10-14 and Comparative Examples 8-9, and the maximum peel strength of the welds was measured.

[0093] The maximum peel strength test method is to use a peel tester to continuously apply uniform force to the weld sample to cause it to peel. The force is applied at a rate of 20 N / min. Peel strength τ = F / A, where F is the maximum peel force and A is the contact area of the weld.

[0094] Example 10: Maximum peel strength τ = 47 N / mm 2 ;

[0095] Example 11: Maximum peel strength τ = 48 N / mm 2 ;

[0096] Example 12: Maximum peel strength τ = 48 N / mm 2 ;

[0097] Example 13: Maximum peel strength τ = 47 N / mm 2 ;

[0098] Example 14: Maximum peel strength τ = 49 N / mm 2 ;

[0099] Comparative Example 8: Maximum peel strength τ = 33 N / mm 2 ;

[0100] Comparative Example 9: Maximum peel strength τ = 27 N / mm 2 ;

[0101] According to the maximum peel strength data of the metal welding materials prepared in Examples 10-14 and Comparative Examples 8-9 measured in Experimental Example 4, it can be seen that the metal welding materials prepared in Examples 10-14 all have relatively excellent maximum peel strength among silver-based brazing materials. For Comparative Example 8, the lack of a composite welding wire structure causes uneven eutectic during the welding process. The uneven melting and cooling process of the welding layer formed by the metal welding material leads to a certain welding stress between the weld and the base material, so that the maximum peel strength of the weld structure is significantly reduced. A similar phenomenon also occurs in Comparative Example 9. Due to the premature sintering of the nanoparticles, the nickel bronze hollow wire 1 cannot be well eutectic with the ternary nanoparticles. The difference in expansion coefficient between the weld and the base material causes a large amount of welding stress to accumulate, resulting in a decrease in weld strength and a significant reduction in the maximum peel strength. In summary, filling the welding wire core material 2 into the nickel bronze hollow wire 1 can effectively combine the characteristics of two materials of different forms, achieve better heat distribution at different stages of welding, improve the uniformity of the welding layer, and the well-eutectic welding layer can effectively reduce the welding stress caused by the difference in thermal expansion coefficient between the weld and the base material, thereby improving the stability of the welding structure.

[0102] Experimental Example 5

[0103] With reference to the experimental methods and parameters of Experimental Examples 3 and 4, the metal welding materials prepared in Examples 15-20 and Comparative Examples 10-11 were subjected to thermal conductivity tests and maximum peel strength tests, and the results are summarized in Table 4.

[0104] Table 4 Thermal conductivity and maximum peel strength of different metal welding materials

[0105] Thermal conductivity (W / m·K) <![CDATA[Maximum peel strength (N / mm 2 )]]> Embodiment 15 175 48 Example 16 174 48 Embodiment 17 177 46 Embodiment 18 176 47 Embodiment 19 171 49 Embodiment 20 174 48 Comparative Example 10 135 29 Comparative Example 11 140 32

[0106] As shown in the thermal conductivity and maximum peel strength data of Table 4, Examples 15-20 all have excellent thermal conductivity and maximum peel strength, and the performance gap between the experimental groups is very small. Due to the lack of the encapsulation process in Comparative Example 10, the ternary nanoparticles cannot be effectively dispersed on the inner surface of the nickel bronze hollow wire 1. The fluidity and wettability of the welding material are reduced during welding, and the uniformity of the welding layer is affected, resulting in a decrease in the thermal conductivity and mechanical strength of the weld formed. In Comparative Example 11, the ultrasonic treatment step in the encapsulation process is lacking, the dispersibility of the ternary nanoparticles is reduced, and the pores and microcracks inside the metal welding material are not reduced, resulting in a decrease in the thermal conductivity and mechanical strength of the weld formed. In summary, the encapsulation process effectively disperses the ternary nanoparticles on the inner surface of the nickel bronze hollow wire 1, while reducing the pores and microcracks inside the metal welding material through ultrasonic treatment, thereby improving the thermal conductivity and mechanical strength of the metal welding material, and improving the thermal conductivity and maximum peel strength of the final weld.

[0107] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art will appreciate that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method of a metal welding material, characterized in that: The preparation method is as follows: Mix the metal precursor solution with a reducing agent and a surfactant, and obtain ternary nanoparticles after solvothermal treatment; The metal precursor solution includes: silver nitrate, indium acetate, zinc acetate and ethylene glycol; the concentration of silver nitrate is 1.5 mol / L, the concentration of indium acetate is 0.3 mol / L, and the concentration of zinc acetate is 1.0 mol / L; the addition amount of the metal precursor solution is 100 parts; the reducing agent includes: sodium citrate and sodium ascorbate, wherein the mass ratio of sodium citrate to sodium ascorbate is 1:2; the addition amount of the reducing agent is 2 - 4 parts; the surfactant includes: polyvinyl alcohol and cetyltrimethylammonium bromide, wherein the mass ratio of polyvinyl alcohol to cetyltrimethylammonium bromide is 5:1; the addition amount of the surfactant is 2 - 3 parts; Put copper powder, tin powder and nickel powder into an induction furnace to melt, and obtain nickel bronze alloy through the alloying process; Conduct tube forming treatment on the nickel bronze alloy to obtain nickel bronze hollow wire (1); Mix the ternary nanoparticles with a soldering flux to obtain a wire core material (2); Preheat the wire core material (2) and then fill it into the nickel bronze hollow wire (1) to obtain a precursor of the welding material, and the precursor of the welding material is obtained as the metal welding material after encapsulation treatment.

2. The preparation method of a metal welding material according to claim 1, wherein: The process of solvothermal treatment is: mix the metal precursor solution, the reducing agent and the surfactant, place them in a hydrothermal kettle, preheat at 200 °C for 30 min, raise the temperature to 300 °C and react for 12 hours under the autogenous pressure of the hydrothermal kettle, cool to 25 °C and then centrifuge for 10 minutes at a rotation speed of 6000 - 8000 rpm to obtain a solid product; wash the solid product with ethanol and deionized water, and then vacuum dry at 60 °C for 24 hours to obtain the ternary nanoparticles.

3. The preparation method of a metal welding material according to claim 1, characterized in that: The alloying process is: put the copper powder, the tin powder and the nickel powder into an induction furnace, raise the temperature to 600 °C and preheat for 20 min, then raise the temperature at a rate of 200 °C / min to 1200 - 1300 °C, ensure that the raw materials are completely melted and then continue to heat for 4 - 6 hours, and blow in nitrogen for degassing to obtain a molten alloy; pour the molten alloy into a tubular mold for cooling and forming to obtain an alloy tube; reheat the alloy tube to 500 - 550 °C for annealing treatment, keep it warm for 8 - 12 hours and then cool it to 25 °C at a rate of 5 °C / min to obtain the nickel bronze alloy.

4. The preparation method of a metal welding material according to claim 1, characterized in that: The process of tube forming treatment is: heat the nickel bronze alloy to 550 - 600 °C and keep it warm for 30 min, use a drawing machine for multiple draws until the diameter of the nickel bronze alloy is less than 1 mm to obtain a hollow wire precursor; cool the hollow wire precursor to 400 °C at a rate of 5 °C / min, keep it warm for 4 hours, and then cool it to 25 °C at a rate of 25 °C / min to obtain the nickel bronze hollow wire (1).

5. The preparation method of a metal welding material according to claim 1, characterized in that: The addition amount of the ternary nanoparticles is 200 parts; the soldering flux is rosin; the addition amount of the soldering flux is 200 parts.

6. The preparation method of a metal welding material according to claim 1, characterized in that: The filling process is as follows: preheat the wire core material (2) and the nickel bronze hollow wire (1) to 120 °C and keep the operating temperature unchanged, and then inject the wire core material (2) into the cavity of the nickel bronze hollow wire (1) using a syringe; the injection speed is the filling speed of the wire core material (2) in the nickel bronze hollow wire (1), wherein the injection speed is 5 cm / min.

7. The preparation method of a metal welding material according to claim 1, characterized in that: The encapsulation process is as follows: spot-weld the two ends of the precursor of the welding material, and after closing the two ends of the precursor of the welding material, perform ultrasonic treatment at a temperature of 50 °C and an ultrasonic frequency of 50 kHz for 2 hours and then cool it to 25 °C at a rate of 10 °C / min to obtain the metal welding material.

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