Brazing filler metal, preparation method, application of brazing filler metal and brazing method

Abstract

The invention discloses brazing filler metal, a preparation method, application of the brazing filler metal and a brazing method. The brazing filler metal is used for solving the problems that when an existing brazing filler metal is used for welding an artificial dissimilar material metal joint, the tissue structure is changed when the temperature is too high, and the tensile strength or shear strength of the welding position is low. The brazing filler metal comprises the following chemical components in percentage by weight: 20-70% of Ti; 10 wt% to 40 wt% of Ni; 5 wt% to 25 wt% of Zr; 1 wt% to 15 wt% of fluxing metal; 1 wt% to 10 wt% of a reinforcing metal; the fluxing metal comprises one or more than two of Sn, Ag and Al; the reinforcing metal comprises one or more than two of Au, Ta, Nb, Ru, V, Cr, Mo, Fe, Hf, W, Re and Pt. According to the brazing filler metal provided by the invention, the brazing temperature is controlled below 980 DEG C, and the titanium alloy is welded below the alpha-to-beta phase transition temperature; and the microstructure of the titanium alloy base material is effectively protected, and tissue structure change caused by high temperature is avoided, so that the original strength, toughness and corrosion resistance of the base material are kept, and the service life of the artificial dissimilar metal joint is prolonged.

Description

Technical Field

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

[0002] With the development of biomedical engineering, artificial metal joints are increasingly used in clinical medicine. Traditional artificial joints are usually made of metal materials such as stainless steel, cobalt-chromium alloys and titanium alloys. In recent years, titanium alloys and tantalum alloys have become ideal materials for manufacturing artificial joints due to their excellent biocompatibility and mechanical properties. Currently, artificial joints are mainly made of the same material, or two materials are connected by mechanical connection to form an artificial joint. The use of the same material to obtain an artificial joint has a single function and cannot simultaneously meet the requirements of good human compatibility and light structure. Therefore, welding titanium alloys and tantalum alloys to obtain artificial joints made of dissimilar materials can give full play to the respective roles of titanium alloys and carbon alloys, and has become the focus of attention for high-performance artificial joints.

[0003] The welding interface of artificial metal joints is very irregular, and the material properties of titanium alloys and tantalum alloys are quite different, which makes it difficult to obtain safe and reliable artificial joints. Therefore, high-quality, high-performance, and high-precision welding technology is the key to realizing the application of heterogeneous and heterogeneous (heterogeneous means two different materials, and heterogeneous means two different structures) metal artificial joints. The connection between titanium alloys and tantalum alloys mainly relies on fusion welding and diffusion welding technology. During the fusion welding process, due to the high temperature, the physical properties of titanium alloys and tantalum alloys are quite different, resulting in large deformation and residual stress of the welded joints. Although diffusion welding can achieve connection at a lower temperature, it is not suitable for artificial joints with complex structures, and the deformation is also large.

[0004] As a high-precision connection technology, brazing has the advantages of low heating temperature, high joint quality, and simple equipment, and has gradually attracted attention. However, brazing titanium alloys and tantalum alloys still faces some challenges, such as the selection of brazing filler metals and the optimization of brazing process parameters. Therefore, the development of a special brazing filler metal and its brazing process to achieve high-precision and high-strength joint connection between titanium alloys and tantalum alloys has important practical significance and application prospects. Existing commercial brazing fillers for connecting titanium alloys and tantalum alloys have low strength and contain many elements that are harmful to the human body, making them unusable. Summary of the invention

[0005] The purpose of the present invention is to solve the above-mentioned shortcomings and provide a solder, a preparation method and application thereof, and a soldering method.

[0006] In the first aspect, a brazing material adopts the following technical solution: A solder, the solder chemical composition includes the following components: Ti 20wt%~70wt%; Ni 10wt%~40wt%; Zr 5wt%~25wt%; Flux metal 1wt%~15wt%; Reinforcement metal 1wt%~10wt%.

[0007] Furthermore, the flux metal includes one or more of Sn, Cu, Ag and Al.

[0008] Furthermore, the reinforcing metal includes one or more of Au, Ta, Nb, Ru, V, Cr, Co, Mo, Fe, Hf, W, Re, and Pt.

[0009] In a second aspect, a method for preparing a solder material adopts the following technical solution: A method for preparing solder, the method comprising preparing powder solder by gas atomization or preparing strip solder by roller spinning; The gas atomization method for preparing powder solder includes the following steps: Weigh Ti, Ni, Zr and flux metal and reinforcement metal raw materials according to mass ratio, add them into a crucible, smelt them in a vacuum or inert environment, spray the smelted metal liquid through a nozzle at high speed to form metal droplets, cool, sieve and wash, and obtain the powder brazing material; The roller stripping method for preparing strip solder includes the following steps: Metal raw materials including Ti, Ni, Zr, fluxing metal and reinforcing metal are weighed according to the mass ratio and added into a crucible, and smelted and homogenized in a vacuum or inert environment. The molten metal is degassed, and then the molten metal is poured onto the surface of a high-speed rotating roller to be quickly drawn into a thin strip and immediately cooled and rolled up to obtain the strip solder.

[0010] In the third aspect, an application of a brazing material adopts the following technical solution: An application of the brazing filler metal as described above in brazing of artificial dissimilar metal joints.

[0011] In a fourth aspect, a brazing method for artificial dissimilar metal joints adopts the following technical solution: A brazing method for artificial dissimilar metal joints, comprising the following steps: uniformly mixing the solder and the binder to prepare a solder paste; Evenly coating the solder paste on the to-be-welded portion of the metal joint; In an inert atmosphere or vacuum environment, slowly heat the to-be-welded portion of the metal joint to 350° C. to 700° C., and keep the temperature for 5 min to 120 min to remove the adhesive; Continue to heat the parts of the metal joints to be welded to 780℃~980℃ for welding, with a heating rate of 5℃ / min~20℃ / min. Keep warm for 5min~120min to ensure that the brazing material is fully melted. After welding is completed, cool with the furnace to complete the brazing of artificial dissimilar metal joints.

[0012] Furthermore, the mass ratio of the solder to the binder is 0.4:1-3:1; the binder includes one of Nicorobraz Cements 320, Nicorobraz Cements 520, and s'binder binder.

[0013] Furthermore, the thickness of the solder paste at the part to be welded is less than 0.2 mm.

[0014] Furthermore, the inert atmosphere is an argon environment with an oxygen content of less than 1%; the vacuum degree of the vacuum environment is less than 1×10⁻ 3 Pa.

[0015] Beneficial effects of the present invention: The solder provided by the present invention can control the brazing temperature below 980°C, and the most suitable solder can be selected according to the α→β phase transition temperature of the titanium alloy, so that the titanium alloy can be welded below the α→β phase transition temperature. The solder can effectively protect the microstructure of the titanium alloy parent material during the welding process, avoid the changes in the organizational structure caused by high temperature, thereby maintaining the original strength, toughness and corrosion resistance of the parent material, and extending the service life of the artificial joint. Secondly, the solder can ensure the stable performance of the welded joint under a wide temperature range and long-term welding conditions, and avoid the strength fluctuation of the joint under different process conditions. Actual tests show that the shear strength of the joint brazed by the solder can reach more than 120 MPa, and the tensile strength can reach more than 150 MPa (both calculated based on the contact area of ​​the welding surface), with excellent fatigue resistance and reliability, and meet the demanding clinical mechanical requirements for artificial joints. DETAILED DESCRIPTION

[0016] The following is a further detailed description of a solder, a preparation method, an application thereof, and a brazing method described in the present invention in conjunction with the examples. For the sake of simplicity of description, this document cannot enumerate all alternative technical features and implementation schemes contained in the present invention. Therefore, those skilled in the art should know that any technical features and implementation schemes in this embodiment do not limit the scope of protection of the present invention, and the scope of protection includes any alternative technical features and implementation schemes adopted by all those skilled in the art without creative labor. Specifically, the implementation schemes obtained by replacing any technical feature in the present invention or combining any two or more technical features provided by the present invention should be within the scope of protection of the present invention.

[0017] This embodiment provides a solder, the chemical composition of the solder includes the following components: Ti 20wt%~70wt%; Ni 10wt%~40wt%; Zr 5wt%~25wt%; Flux metal 1wt%~15wt%; Reinforcement metal 1wt%~10wt%.

[0018] Ti (20wt%~70wt%) in the brazing filler metal provides basic biocompatibility and toughness, enabling it to have good bonding ability with titanium alloy workpieces while meeting the strict requirements of medical devices for biosafety; the addition of Ni (10wt%~40wt%) significantly improves the tensile strength and fatigue properties of the brazing filler metal, making the welded joint stable when subjected to high-intensity loads; the introduction of Zr (5wt%~25wt%) further optimizes the corrosion resistance and microstructural stability of the joint, and can effectively resist the corrosion of human body fluids in long-term use environments.

[0019] Flux metal (1wt%~15wt%) lowers the melting point of the brazing filler metal and improves wettability, enabling the brazing filler metal to melt and flow at a lower temperature, thereby reducing thermal damage to the base material during welding and significantly improving the uniformity and density of the welded joint. Reinforcing metal (1wt%~10wt%) improves the mechanical properties of the joint through the mechanism of solid solution or precipitation strengthening, and enhances the fatigue resistance and crack propagation resistance of the welded joint.

[0020] This brazing material optimizes the composition ratio while taking into account the flexibility of the processing technology. It can be prepared into a uniform powder brazing material through gas atomization, or into a thin strip brazing material through the strip-throwing process, and has a wide range of adaptability. Under the optimization of brazing temperature (780℃~980℃) and process parameters, it can achieve reliable connection between titanium alloy and tantalum alloy, while minimizing residual stress and deformation during welding.

[0021] The brazing material provided in this embodiment not only solves the limitations of traditional brazing materials in mechanical properties and biocompatibility, but also provides an efficient solution for the welding of dissimilar materials between titanium alloy and tantalum alloy through dual optimization of composition and process, greatly broadening its application prospects in the manufacture of artificial metal joints.

[0022] In some embodiments, the flux metal includes one or more of Sn, Cu, Ag, and Al.

[0023] In these embodiments, the wetting properties, melting behavior, and quality and performance of the solder joints are further optimized by introducing flux metals (one or more of Sn, Cu, Ag, and Al) into the solder formula. The selection and proportion of flux metals have an important influence on the soldering process and joint performance.

[0024] The addition of flux metals, especially Sn and Ag, significantly reduces the melting point range of the brazing filler metal, allowing it to melt at a relatively low temperature. The lower welding temperature reduces the thermal damage to the base material, avoids microstructural changes and residual stress accumulation at the interface of titanium alloy and tantalum alloy caused by high temperature, and reduces deformation during welding. This low-temperature brazing characteristic provides technical support for the manufacture of artificial joints with complex geometries and ensures the accuracy and stability of the joints.

[0025] Flux metals such as Cu, Sn, and Ag significantly enhance the wettability of the brazing material on the surface of titanium alloy and tantalum alloy by reducing the surface tension of the brazing material. The improved wettability enables the brazing material to fully cover and fill the interface of dissimilar metals, forming a dense weld structure, thereby improving the mechanical strength and fatigue resistance of the joint. In addition, the improved wettability also reduces the porosity and defects during the welding process, making the welded joint more stable.

[0026] The introduction of Cu and Ag promotes the mutual diffusion of elements at the interface of titanium alloy and tantalum alloy during welding, forming a stable metallurgical bond. It effectively improves the shear strength and tensile strength of the welded joint, allowing the joint to withstand higher mechanical loads. The alloying effect of the flux metal also improves the ductility of the joint, reduces the risk of brittle fracture, and meets the strict requirements of artificial metal joints for high mechanical properties.

[0027] The introduction of Ag and Al as flux metals not only plays an important role in lowering the melting point and improving wettability, but also enhances the corrosion resistance of the welded joint. Ag has excellent antioxidant ability and forms a stable oxide film protective layer during the welding process, which effectively resists corrosion in the human body fluid environment. In addition, the aluminum oxide film formed by Al at the welding interface also has high corrosion resistance. This protective mechanism prolongs the service life of the artificial joint.

[0028] When two or more fluxing metals (such as Cu-Sn, Ag-Sn, etc.) are used, their synergistic effect further optimizes the melting point, wettability and diffusion properties of the solder. For example, the Cu-Sn combination can not only reduce the melting point, but also enhance the metallurgical bonding of the weld; the Ag-Sn combination significantly improves the comprehensive performance of the welded joint by providing excellent wettability and corrosion resistance. This synergistic effect enables the solder to better adapt to complex welding environments and different application scenarios.

[0029] The introduction and combination design of flux metals (Sn, Cu, Ag, Al) in this embodiment achieves comprehensive optimization of solder performance. By lowering the melting point, improving wettability, enhancing mechanical properties and improving corrosion resistance, the solder can reliably connect titanium alloy and tantalum alloy, providing an efficient, stable and controllable welding solution for artificial joint manufacturing. It not only meets the technical requirements of complex dissimilar material welding, but also significantly improves the accuracy and service life of the welded structure, laying a solid foundation for innovative applications in the field of biomedical engineering.

[0030] In some embodiments, the reinforcing metal includes one or more of Au, Ta, Nb, Ru, V, Cr, Co, Mo, Fe, Hf, W, Re, and Pt.

[0031] In these embodiments, by introducing reinforcing metals (such as one or more of Au, Ta, Nb, Ru, V, Cr, Co, Mo, Fe, Hf, W, Re, and Pt) into the brazing material, the comprehensive performance of the brazing material in the connection of dissimilar materials between titanium alloy and tantalum alloy is significantly enhanced. The characteristics of the reinforcing metal and its role in the brazing process have important contributions to the strength, durability, and stability of the welded joint.

[0032] Reinforcement metals improve the tensile strength and shear strength of welded joints through solid solution strengthening and precipitation strengthening mechanisms. For example, Ta and Nb significantly improve the load-bearing capacity of welded joints by forming fine, evenly distributed strengthening phases during brazing; the addition of Cr and Co helps to enhance the hardness and wear resistance of welds, especially for high-load artificial joint applications; Mo and W increase the high-temperature strength of the brazing filler metal, making welded joints more stable when subjected to dynamic loads or long-term use.

[0033] Reinforcement metals such as Au, Pt, and Hf can form dense protective films or stable intermetallic compounds at the interface during welding. These structures have excellent barrier properties against corrosive media (such as simulated body fluids). For example, the chemical stability of Au and Pt enables them to significantly improve the corrosion resistance of welded joints, especially in long-term immersion or biological environments, where welds exhibit extremely low corrosion rates; the addition of Hf further enhances the corrosion resistance of welded joints and extends the service life of artificial metal joints.

[0034] Reinforcement metals such as V, Re, and Ru help to form fine grains or directional structures by adjusting the solidification behavior of the brazing filler metal during welding. This optimization of the microstructure can significantly reduce the residual stress in the weld and avoid the degradation of mechanical properties caused by grain coarsening or component segregation. For example, the addition of Re can significantly improve the crack propagation resistance of the weld, thereby improving the fatigue performance and service reliability of the welded joint.

[0035] The selection of reinforcing metals takes into account the strict requirements for material safety in the biomedical field. Metals such as Ta and Nb are widely used in medical devices due to their excellent biocompatibility. Their addition not only enhances the performance of the weld, but also ensures the biosafety of the welded joint in the human environment, avoiding biotoxic reactions caused by the release of harmful elements from the material.

[0036] In some embodiments, the combination of reinforcing metals (such as Ta-Nb, Mo-W, Re-Pt, etc.) further improves the comprehensive performance of the brazing filler metal. For example, the Ta-Nb combination can simultaneously enhance the strength and ductility of the welded joint, making the weld have better fatigue resistance under dynamic loads; the Mo-W combination improves the high temperature stability and wear resistance of the brazing filler metal, making it suitable for artificial joint parts with complex geometries or high-load applications; the Re-Pt combination optimizes corrosion resistance and wettability in a coordinated manner, making the brazing filler metal perform better during welding and long-term use.

[0037] The introduction of reinforcing metals also optimizes the welding process parameters of the brazing filler metal, enabling it to achieve stable welding results over a wide temperature range. For example, the addition of Ru and V improves the molten fluidity of the brazing filler metal, enabling it to more evenly fill the welding interface of complex shapes and form a dense weld; the presence of Cr enhances the stability of the weld at high temperatures and reduces deformation and stress concentration during welding.

[0038] By introducing reinforcing metal, the brazing material of this embodiment not only achieves comprehensive optimization in terms of mechanical properties, corrosion resistance and biocompatibility, but also improves the adaptability and stability of the brazing process through the synergistic effect between metals.

[0039] This embodiment provides a method for preparing solder, which includes preparing powder solder by gas atomization or preparing strip solder by roller spinning; Preparation of powder solder by gas atomization includes the following processes: Weigh Ti, Ni, Zr and flux metal and reinforcement metal raw materials according to mass ratio and add them into a crucible, smelt them in a vacuum or inert environment, spray the smelted metal liquid through a nozzle at high speed to form metal droplets, cool, sieve and wash to obtain powder solder; The preparation of strip solder by roller spinning includes the following processes: The metal raw materials of Ti, Ni, Zr, flux metal and reinforcing metal are weighed according to the mass ratio and added into the crucible, and smelted and homogenized in a vacuum or inert environment. The metal liquid is degassed, and then the metal liquid is poured onto the surface of a high-speed rotating roller to be quickly pulled into a thin strip and immediately cooled and rolled to obtain a strip solder.

[0040] The solder preparation method provided in this embodiment realizes the multi-form preparation of solder through two different processes (gas atomization powder making and roller strip spinning), providing high-performance and multifunctional solder for different welding requirements. This preparation method takes into account the uniformity of ingredients, product quality control and adaptability in process design, laying the foundation for the reliability and flexibility of the brazing process.

[0041] Preparation of powder solder by gas atomization The powder solder prepared by gas atomization technology has uniform particle size distribution, smooth surface, high sphericity, and excellent fluidity and dispersibility. This feature ensures the uniform distribution of the solder at the welding interface, making the weld denser and the joint performance more stable.

[0042] In addition, the gas atomization process is carried out in a vacuum or inert environment, which effectively reduces the chance of the metal liquid coming into contact with oxygen or nitrogen during the smelting and atomization process, thereby reducing the impurity content and improving the purity and biocompatibility of the solder.

[0043] Rapid control of the cooling rate avoids the problem of grain coarsening, forms a finer and more uniform microstructure, and further enhances the corrosion resistance of the brazing filler metal and the mechanical strength of the welded joint.

[0044] Powder brazing filler metal is suitable for welding workpieces with high complexity or diversified shapes, and shows excellent adaptability, especially in brazing processes that require precise coating or filling of specific shapes.

[0045] Preparation of strip solder by roller spinning The strip solder produced by the roller strip-spinning technology has uniform thickness and high density, which is particularly suitable for large-area welding or wide welding joints. Through the high-speed rotating copper roller surface stretching and rapid cooling, the solder strip can be quickly solidified, thereby avoiding component segregation and reducing the generation of internal stress. This thin strip structure can be directly applied to the welding interface without additional processing, simplifying the welding process and improving production efficiency.

[0046] The introduction of degassing treatment effectively removes gas impurities that may be mixed into the smelting process before the molten metal flows to the rollers, ensuring the density and quality consistency of the strip.

[0047] Melting in a vacuum or inert environment further avoids oxidation and contamination, making the strip solder have excellent chemical purity and stability, meeting the requirements of high-performance brazing processes.

[0048] The two preparation methods of gas atomization and roller stripping complement each other and adapt to different application scenarios. For example, powder solder is more suitable for precision welding process, especially when welding complex curved surfaces or small welding areas, it can be accurately coated in the form of solder paste; while strip solder is more suitable for fast and mass production of larger planes or regular welding areas, providing an efficient solution for industrial applications.

[0049] The flexibility of the preparation method not only meets the specific needs of welding dissimilar materials (such as titanium alloy and tantalum alloy), but also improves the versatility of brazing filler metal preparation and broadens its potential applications in other industrial fields.

[0050] Both preparation methods are carried out under vacuum or inert atmosphere, which reduces the oxidation problem common in traditional smelting processes, reduces the generation of waste gas and waste, and is more environmentally friendly. The application of rapid cooling technology not only improves the performance of the brazing material, but also shortens the process cycle and improves production efficiency.

[0051] The solder preparation method in this embodiment successfully achieves high-quality production of solder in both powder and thin strip forms through gas atomization and roller stripping technology. Both the fluidity and dispersibility of the powder and the uniformity and density of the thin strip provide reliable guarantees for the efficient implementation of the brazing process. This preparation method not only optimizes the performance of the solder, ensures the high strength and long life of the welded joint, but also greatly improves the flexibility and applicability of solder production.

[0052] This embodiment also provides an application of the brazing filler metal as described above in brazing of artificial dissimilar metal joints.

[0053] The application of the brazing filler metal provided in this embodiment in the brazing of artificial dissimilar metal joints achieves a reliable connection between the titanium alloy and the tantalum alloy by optimizing the chemical composition of the brazing filler metal.

[0054] Due to the significant differences in physical and chemical properties (such as thermal expansion coefficient and melting point) between titanium alloy and tantalum alloy, it is often difficult to achieve stable connection between them by traditional welding methods. The solder component system of this embodiment significantly enhances the wettability and metallurgical bonding strength of the welding interface, allowing the solder to fully fill the joint area and form a high-quality weld, thereby achieving a reliable connection between dissimilar metals.

[0055] The addition of Ni and Zr to the brazing filler metal, as well as the synergistic effect of flux metal and reinforcing metal, enables the weld to exhibit excellent mechanical properties under high-temperature welding and long-term use conditions. The shear strength of the welded joint exceeds 120 MPa, and the tensile strength reaches more than 150 MPa. This high strength and high stability can meet the requirements of artificial metal joints to withstand dynamic loads in the human body for a long time, effectively extending the service life of the joint.

[0056] The metal components used in the solder (such as Ti, Ta, Nb, Hf, etc.) are all materials with good biocompatibility and will not release harmful ions or cause inflammatory reactions in the human body environment. This feature ensures that the welded joint can be used safely after implantation in the human body, avoiding the biosafety issues caused by the presence of toxic elements such as Pb and Cd in traditional solders.

[0057] Artificial joints usually have complex geometric structures (such as hip joint ball heads, acetabular cups, knee joint sliders, etc.). The solder of this embodiment exhibits excellent fluidity and wettability during welding, and can meet the welding requirements of these complex geometric shapes. By controlling the melting point and welding temperature of the solder, the deformation and residual stress of the base material during welding are reduced, making the combination of the weld and the base material more uniform and dense.

[0058] Titanium alloys and tantalum alloys may face corrosion problems in body fluid environments. This solder significantly enhances the corrosion resistance of the weld in simulated body fluids (such as PBS solution) by introducing corrosion-resistant elements such as Zr, Ag, and Pt. Experiments show that the welded joint has no obvious corrosion after 500 hours of immersion in simulated body fluids, providing a reliable guarantee for the long-term stability of artificial joints.

[0059] Powder solder prepared by atomization is suitable for solder paste coating process, which is convenient for precise operation in welding areas of small area or complex structure; thin strip solder prepared by roller stripping is suitable for welding needs of larger area, which greatly improves the efficiency and applicability of welding process.

[0060] The application of the brazing material provided in this embodiment in the brazing of artificial heterogeneous metal joints solves the problem of traditional welding methods in the connection of heterogeneous materials by efficiently connecting titanium alloy and tantalum alloy, and shows excellent advantages in mechanical properties, biocompatibility, corrosion resistance and applicability. This brazing material and its application not only meet the strict requirements of the medical device industry for artificial joints, but also provide technical support for the research and development and promotion of high-performance artificial metal joints, and have important clinical value and market prospects.

[0061] This embodiment provides a method for brazing artificial dissimilar metal joints, including the following process: The solder and the binder are uniformly mixed to form a solder paste; Apply solder paste evenly to the parts of metal joints to be welded; In an inert atmosphere or vacuum environment, slowly heat the metal joint to be welded to 350℃~700℃ and keep it warm for 5min~120min to remove the adhesive; Continue to heat the parts of the metal joints to be welded to 780℃~980℃ for welding, with a heating rate of 5℃ / min~20℃ / min. Keep warm for 5min~120min to ensure that the brazing material is fully melted. After welding is completed, cool with the furnace to complete the brazing of artificial dissimilar metal joints.

[0062] The method of this embodiment effectively reduces the thermal stress and residual stress that may occur during the welding process through staged temperature control and slow heating rate. In the first stage, the temperature is slowly raised to 350℃~700℃ and kept warm for 5~120min, which helps to fully volatilize the binder in the solder paste and avoid residues or gas inclusions during the welding process, thereby improving the density and stability of the welded joint.

[0063] In the second stage, the temperature is further increased to 780℃~980℃, within which the brazing filler metal can be fully melted without significant thermal damage to the base metal. The optimized setting of the heating rate (5℃ / min~20℃ / min) can not only avoid cracks in the weld joint caused by sudden temperature changes, but also ensure the uniform distribution of the brazing filler metal in the weld area, thus significantly enhancing the mechanical properties of the weld joint.

[0064] In the present embodiment, the welding process is carried out in an inert atmosphere (argon with an oxygen content of less than 1%) or a high vacuum environment (vacuum degree <1×10⁻ 3 The welding process is carried out under 3000 Pa, which effectively inhibits oxidation and pollution. This environmental control reduces the generation of impurities in the weld, ensures the chemical purity and microstructural uniformity of the welded joint, and the welded joint has stronger corrosion resistance and better biocompatibility.

[0065] Mixing solder and binder to make solder paste and evenly coating it on the part to be welded not only improves the wettability of solder at the welding interface, but also ensures the uniform distribution of solder on the surface of complex geometric shapes. It can significantly improve the overall uniformity of the welded joint, avoid weld weaknesses caused by local lack of material or uneven coating, and improve the overall strength and reliability of the welded joint.

[0066] The low-temperature brazing technology (welding temperature 780℃~980℃) is used to effectively avoid the microstructural changes caused by high-temperature melting of the parent material or excessive heat-affected zone. This feature is particularly important in the welding of dissimilar materials such as titanium alloy and tantalum alloy, which can ensure that the joint parts after welding maintain their original mechanical properties, corrosion resistance and biocompatibility. In addition, the post-welding furnace cooling method further reduces the thermal stress and weld cracking risks caused by rapid cooling.

[0067] The method of this embodiment is applicable to artificial joint parts of various complex shapes (such as hip joint ball heads, knee joint sliders, etc.). By accurately controlling the temperature, time and environmental parameters during the welding process, it can efficiently achieve stable connections between a variety of heterogeneous materials. This flexibility not only meets the needs of standardized mass production, but also enables the customization of personalized artificial joints for specific patients.

[0068] The joint parts welded by the method of this embodiment have excellent shear strength (above 120MPa) and tensile strength (above 150MPa), and can maintain stability under complex dynamic load conditions of the human body. In addition, the corrosion resistance of the welded joint in a simulated body fluid environment has also been significantly improved, effectively extending the service life of the artificial joint.

[0069] The brazing method provided in this embodiment is based on precise process control, optimized environmental conditions and high-performance brazing filler metal, and realizes the reliable connection of titanium alloy and tantalum alloy in the manufacture of artificial joints. It shows significant advantages in welding quality, mechanical properties, biocompatibility and corrosion resistance, and provides important technical guarantee and practical value for the manufacture of high-performance artificial joints.

[0070] In some embodiments, the mass ratio of the solder to the binder is 0.4:1-3:1; the binder includes one of NicrobrazCements 320, Nicrobraz Cements 520, and s'binder binder.

[0071] The mass ratio of solder to binder is in the range of 0.4:1~3:1, which makes the solder paste have good fluidity and coating uniformity. This ratio design not only ensures the full coverage of the solder at the welding interface, but also avoids welding defects caused by too much or too little binder.

[0072] When the ratio of solder to binder is low (0.4:1), the solder paste has stronger adhesion, which is suitable for welding complex geometric structures and can prevent the solder from falling off during welding; while a higher ratio (close to 3:1) ensures sufficient supply of solder, which further enhances the density and strength of the weld. This flexible ratio range meets the needs of various welding scenarios.

[0073] Nicrobraz Cements 320, Nicrobraz Cements 520 and s'binder adhesives have good adhesion, thermal decomposition and welding stability. These adhesives can firmly adhere to the surface of the part to be welded during the solder paste coating process, and can effectively prevent the solder from slipping or falling off even in complex curved surfaces or vertical welding. In the process of heating the welding temperature to 350℃~700℃ and keeping the temperature, the adhesive can completely volatilize or decompose, and no harmful substances will remain in the weld. After mixing with the solder, these adhesives can maintain stable chemical and physical properties and will not deteriorate due to long-term storage or high-temperature welding, thereby improving the repeatability and consistency of the welding process.

[0074] The combination of high-quality binder and reasonable mass ratio enables the solder paste to be evenly coated on the welded parts of the metal joints, forming a stable and continuous solder layer. In the subsequent heating and welding process, the solder can fully fill the welding interface, effectively reduce welding defects such as pores and cracks, and significantly improve the density and strength of the weld.

[0075] This ratio range and the flexibility of binder selection enable the brazing process to adapt to artificial joint components of different shapes and sizes. For example, in small and complex joint structures (such as knee sliders), a higher binder ratio provides better coating stability; while in large-area welding scenarios (such as acetabular cup and ball head connection), a higher brazing filler metal ratio ensures sufficient supply of welding materials.

[0076] The above-mentioned adhesive will not release harmful gases or residues to the human body or the environment after volatilization or decomposition, which fully meets the strict requirements of material safety in the biomedical field. This environmentally friendly feature provides long-term biosafety for artificial joints after welding, and also reduces the environmental impact during the production process.

[0077] By optimizing the ratio and selection of brazing filler metal and binder, the artificial dissimilar metal joints after brazing show significant advantages in mechanical properties, welding accuracy and service life. The shear strength and tensile strength of the welded joint exceed 120MPa and 150MPa respectively, and the uniformity and corrosion resistance of the weld are also significantly improved.

[0078] In some embodiments, the thickness of the solder paste at the part to be soldered is less than 0.2 mm.

[0079] The solder paste with a coating thickness of less than 0.2mm can be evenly distributed on the part to be welded, avoiding the problem of local solder accumulation due to excessive thickness or insufficient coverage due to too thin a thickness. This uniform coating can ensure that the solder is completely melted and fills the weld interface during welding, effectively reducing defects such as pores, inclusions and incomplete penetration in the weld, thereby significantly improving the density and uniformity of the welded joint.

[0080] Thinner solder paste is easier to melt and quickly diffuse to the welding interface during welding, thus shortening the high temperature exposure time. Shorter high temperature exposure time helps to reduce the heat affected zone of the base material, reduce the microstructural changes, strength loss and residual stress of the base material caused by high temperature. This feature is particularly critical for dissimilar materials such as titanium alloys and tantalum alloys with high thermal sensitivity, and can effectively protect the original properties of the base material.

[0081] The solder paste with a coating thickness of <0.2mm forms a thin but continuous solder layer during the welding process, and the transition between the solder paste and the base material is smoother. This interface transition avoids local stress concentration, significantly improves the shear strength and tensile strength of the welded joint, and enables the joint to better withstand dynamic loads and fatigue stress from long-term use.

[0082] For artificial joint parts with complex geometric shapes (such as hip joint ball heads, acetabular cups, knee joint sliders, etc.), the solder paste coating thickness of <0.2mm can better adapt to the shape characteristics of the welding surface and ensure that the solder covers all areas that need to be welded. This design can effectively avoid welding dead angles or incomplete connections caused by uneven thickness and improve welding accuracy and reliability.

[0083] Thinner solder paste can reduce excess solder residue after welding, making the weld surface smoother. It not only reduces the workload of post-weld cleaning, but also avoids stress concentration or defects on the weld surface caused by excess solder accumulation, thereby further improving the overall performance and appearance quality of the welded structure.

[0084] Controlling the thickness of the solder paste to <0.2mm can improve the controllability of the welding process, reduce manual operation errors, and ensure consistent performance of each welded joint.

[0085] Controlling the thickness of the solder paste at the welded part to less than 0.2mm not only ensures the uniformity and density of the welding interface, but also reduces material waste and thermal impact of the parent material, while improving the strength and precision of the welded joint. It is particularly suitable for the manufacture of artificial metal joint parts with complex geometric structures, providing strong technical support for achieving high-quality, high-efficiency and high-adaptability brazing processes, and significantly improving the reliability and service life of artificial joints.

[0086] In some embodiments, the inert atmosphere is an argon environment with an oxygen content of less than 1%; the vacuum degree of the vacuum environment is less than 1×10⁻ 3 Pa.

[0087] Titanium alloys and tantalum alloys are very easy to oxidize in high temperature environments. The formation of oxide layers will hinder the wetting and diffusion of the solder, thereby reducing the strength and density of the welded joint. In an argon environment with an oxygen content of less than 1% or a vacuum degree of less than 1×10⁻ 3 Under the condition of Pa, the oxidation reaction is effectively suppressed and the material surface can be kept clean during brazing. This pure interface condition ensures a good metallurgical bond between the brazing material and the base material, greatly improving the mechanical properties and corrosion resistance of the weld.

[0088] Impurity elements such as oxygen and nitrogen can easily penetrate into the brazing filler metal and the base metal at high temperatures, forming brittle compounds or inclusions, which affect the uniformity and toughness of the welded joint. Low-oxygen argon or high vacuum environments can significantly reduce the entry of these impurities, making the weld structure denser and free of inherent defects, and making the mechanical properties of the welded joint more stable.

[0089] Inert atmosphere and vacuum environment help reduce the surface tension of the brazing material during melting, thereby improving the wettability of the brazing material on the surface of titanium alloy and tantalum alloy. Good wettability enables the brazing material to evenly cover the welding interface and quickly fill small gaps, while promoting the diffusion and metallurgical bonding of elements between the brazing material and the base material, further enhancing the strength and durability of the welded joint.

[0090] In a high vacuum environment, the convection and radiation heat transfer effects of the gas are greatly weakened, and the temperature gradient during welding is small, which helps to reduce the thermal stress generated during welding and the residual stress formed during cooling. The reduction of residual stress not only reduces the crack tendency of the welded joint, but also improves the stability and service life of the joint structure under dynamic loads.

[0091] During the brazing process, the avoidance of oxidation and impurities can effectively reduce the electrochemically active area in the welded joint, greatly improving the corrosion resistance of the welded joint in corrosive environments such as body fluids. This feature is crucial to extending the service life of artificial metal joints, especially under the condition of long-term implantation in the human body, which can significantly reduce the risk of joint performance degradation caused by corrosion.

[0092] The precise control of inert atmosphere and vacuum environment enables the welding process to adapt to joint components of different geometries and sizes. Whether it is a hip ball head, acetabular cup, knee slider or other complex structural components, high-precision welding can be achieved in a high-purity environment to ensure the consistency and stability of the welding effect.

[0093] Artificial joints have extremely high requirements for the mechanical properties, biocompatibility and corrosion resistance of welded joints. Using low-oxygen argon or high vacuum environments can not only meet these requirements, but also significantly improve the controllability and repeatability of the welding process. Experiments have shown that the shear strength of welded joints completed in this environment can reach more than 120MPa, the tensile strength exceeds 150MPa, and it also exhibits excellent fatigue resistance and durability.

[0094] In an argon environment with an oxygen content of less than 1% or a vacuum degree of less than 1×10⁻ 3 Under the condition of 2.5°C Pa, the brazing method of this embodiment significantly improves the purity, mechanical properties and corrosion resistance of the welded joint, while reducing defects and deformation during the welding process. It not only meets the strict requirements of high-performance artificial joint manufacturing, but also enhances the adaptability and stability of the welding process, provides strong technical support for the mass production of artificial metal joints, and has broad application prospects and clinical value.

[0095] Example The component raw materials of the solder in the following examples are selected as follows: Ti: high-purity titanium powder (Ti>99.9wt%), medical titanium alloy powder (TC4, Ti-6Al-4V), titanium particles or titanium sponge; Zr: high purity zirconium powder (Zr ≥ 99.9%), zirconium alloy powder (such as Zr-Nb, Zr-Sn), zirconium particles or zirconium strips; Ni: high purity nickel powder (Ni ≥ 99.9%), nickel alloy powder (such as Ni-Cr, Ni-Mo), nickel strip or nickel granules; Flux metal and reinforcement metal: high purity metal powder or particles (purity>99.9wt%).

[0096] The solders in the following examples are all prepared by the following preparation methods. The method for preparing powder solder comprises the following steps: Weigh Ti, Ni, Zr, flux metal and reinforcing metal raw materials according to the mass ratio and add them into the crucible, vacuum (vacuum degree less than 1×10⁻ 3 Pa) or inert environment (oxygen content less than 1%) at a temperature of 1200℃~1500℃, the smelted metal liquid is sprayed out at high speed through a nozzle to form metal droplets, cooled, sieved, and the surface oxide film is cleaned to obtain powder solder with a particle size of 20μm~50μm.

[0097] The method for preparing a strip solder comprises the following steps: Weigh Ti, Ni, Zr, flux metal and reinforcing metal raw materials according to the mass ratio and add them into the crucible, vacuum (vacuum degree less than 1×10⁻ 3The molten metal is melted at 1200℃~1500℃ in an inert environment (oxygen content is less than 1%), homogenized for 10min~15min, and degassed. The molten metal is then poured onto the surface of a copper roller with a rotation speed of 2000rpm~3000rpm to be quickly pulled into a thin strip and immediately cooled, coiled, and then a strip solder is obtained with a thickness of 20μm~100μm.

[0098] The preparation method of the above powder solder or strip solder further includes the step of: performing annealing treatment in a vacuum or inert gas protection environment at 400°C to 600°C to release internal stress and improve the ductility and flexibility of the strip.

[0099] Example 1 Embodiment 1 provides a solder, the chemical composition of which includes the following components: Ti 40wt%, Ni 20wt%, Zr 25wt%, Sn 10wt% and Ta 5wt%.

[0100] Embodiment 1 also provides a method for brazing artificial dissimilar metal joints, comprising the following steps: The powdered brazing material and the binder Nicrobraz Cements 320 are uniformly mixed at a mass ratio of 0.4:1 to prepare a brazing paste; the brazing paste is uniformly applied to the part to be welded of the metal joint, and the thickness of the brazing paste is 0.2 mm; In a vacuum environment (vacuum degree <1×10⁻ 3 Pa), slowly heat the metal joint to be welded to 350℃, keep it warm for 120min to remove the binder; continue to heat the metal joint to be welded to 780℃ for welding, the heating rate is 5℃ / min, keep it warm for 120min, cool with the furnace, and complete the brazing of artificial dissimilar metal joints.

[0101] Example 2 Embodiment 2 provides a solder, the chemical composition of which includes the following components: Ti 49wt%, Ni 18wt%, Zr 20wt%, Cu 8wt% and Mo 5wt%.

[0102] Embodiment 2 also provides a method for brazing artificial dissimilar metal joints, comprising the following steps: The powdered solder and the binder Nicrobraz Cements 520 are uniformly mixed in a mass ratio of 1.5:1 to prepare a solder paste; the solder paste is uniformly applied to the part to be welded of the metal joint, and the thickness of the solder paste is 0.2 mm; In a vacuum environment (vacuum degree <1×10⁻ 3Pa), slowly heat up the metal joint to be welded to 500℃, keep warm for 60min to remove the binder; continue to heat up the metal joint to be welded to 850℃ for welding, the heating rate is 12℃ / min, keep warm for 60min, cool with the furnace, and complete the brazing of artificial dissimilar metal joints.

[0103] Example 3 Embodiment 3 provides a solder, the chemical composition of which includes the following components: Ti 50wt%, Ni 25wt%, Zr 22wt%, Ag 5wt% and Hf 3wt%.

[0104] Embodiment 3 also provides a method for brazing artificial dissimilar metal joints, comprising the following steps: The powdered solder and the binder s'binder are uniformly mixed in a mass ratio of 3:1 to prepare a solder paste; the solder paste is uniformly applied to the part to be welded of the metal joint, and the thickness of the solder paste is 0.2 mm; In a vacuum environment (vacuum degree <1×10⁻ 3 Pa), slowly heat the metal joint to be welded to 700℃, keep warm for 5 minutes to remove the binder; continue to heat the metal joint to be welded to 980℃ for welding, the heating rate is 20℃ / min, keep warm for 5 minutes, cool with the furnace, and complete the brazing of artificial dissimilar metal joints.

[0105] Example 4 Embodiment 4 provides a solder, the chemical composition of which includes the following components: Ti 25wt%, Ni 40wt%, Zr 20wt%, Al 10wt% and Fe 5wt%.

[0106] Embodiment 4 also provides a method for brazing artificial dissimilar metal joints, comprising the following steps: The powdered brazing material and the binder Nicrobraz Cements 320 are uniformly mixed in a mass ratio of 1:1 to prepare a brazing paste; the brazing paste is uniformly applied to the part to be welded of the metal joint, and the thickness of the brazing paste is 0.2 mm; In a vacuum environment (vacuum degree <1×10⁻ 3 Pa), slowly heat up the metal joint to be welded to 650℃, keep warm for 20min to remove the binder; continue to heat up the metal joint to be welded to 950℃ for welding, the heating rate is 15℃ / min, keep warm for 30min, cool with the furnace, and complete the brazing of artificial dissimilar metal joints.

[0107] The chemical composition of the solder provided in Examples 5 to 10 is shown in Table 1. The brazing method of artificial dissimilar metal joints provided in Examples 5 to 10 is the same as that in Example 2.

[0108] Table 1 Chemical composition of solder provided in Examples 5 to 10

[0109] Comparative Example The brazing materials provided in Comparative Examples 1 to 10 are conventional brazing materials, and their chemical compositions are shown in Table 2 below. The brazing methods for artificial dissimilar metal joints provided in Comparative Examples 1 to 10 are the same as those in Example 2.

[0110] Table 2 Chemical composition of solder provided in Comparative Examples 1 to 10

[0111] Application Examples The solders provided in Examples 1-10 and Comparative Examples 1-10 were used to weld titanium alloy and tantalum foam discs.

[0112] Sample preparation before welding: The titanium alloy used for joint strength test has a diameter of 20mm, a length of 30mm, and a flat welding surface with a roughness not higher than Ra1.6. The diameter of the tantalum foam is 20mm, the thickness is 2-4mm, and the parallelism of the upper and lower surfaces is less than 0.1mm.

[0113] Assembly before welding: Place the tantalum foam disc between two titanium alloy rods, and lay brazing material between the tantalum foam disc and the titanium alloy rod.

[0114] Welding: Brazing was performed using the brazing methods provided in Examples 1-10 and Comparative Examples 1-8.

[0115] Performance Testing 1. Shear strength test Use a universal testing machine or pressure testing machine to perform a shear performance test on the welded joint provided in the corresponding use case. Place the welded sample flat in the shear sample fixture, with the weld seam flush with the outer extension of the circular hole of the fixture. Place the sample and the shear fixture in the test area of ​​the universal testing machine or pressure testing machine. Start applying a shear load to the sample at a constant speed, which is usually set to 2 mm / min. Record the change in load during the loading process until the sample breaks. Record the maximum load at the time of fracture, which is the maximum load-bearing capacity of the sample in the shear test.

[0116] The shear strength is calculated based on the maximum load and the area of ​​the weld zone using the following formula: τ=Fmax / A Where τ is the shear strength (unit: MPa), Fmax is the maximum load at fracture (unit: N), and A is the area of ​​the welding area (unit: mm²).

[0117] 2. Tensile strength test The tensile strength test of the post-weld joint is carried out in accordance with the corresponding use case of the national standard GB / T 228-2021 Metal Material Tensile Test.

[0118] The test results of the shear strength and tensile strength of the welded joint provided in the application example are shown in Table 3 below.

[0119] Table 3 Performance test of the solder joints after welding provided by Examples 1-10 and Comparative Examples 1-10 in the application examples

[0120] From the results in Table 3, the solder provided by Examples 1-10 is significantly better than Comparative Examples 1-10 in terms of shear strength and tensile strength, showing the obvious effect of the solder composition optimization provided by the present invention. The shear strength of the embodiment ranges from 120MPa to 129MPa, and the tensile strength ranges from 145MPa to 158MPa, while the shear strength of the comparative example is only 58MPa to 78MPa, and the tensile strength is 82MPa to 109MPa. The data show that the solder provided by the embodiment of the present invention has significant advantages in welding strength and joint performance compared with traditional solder.

[0121] For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here, and the obvious changes or modifications derived from them are still within the scope of protection of the claims of the invention.

Claims

1. A solder, characterized in that: The solder chemical composition includes the following components: Ti 20wt%~70wt%; Ni 10wt%~40wt%; Zr 5wt%~25wt%; Flux metal 1wt%~15wt%; Reinforcement metal 1wt%~10wt%; The flux metal includes one or more of Sn, Ag and Al; The reinforcing metal includes one or more of Au, Ta, Nb, Ru, V, Cr, Mo, Fe, Hf, W, Re, and Pt.

2. A method for preparing the solder according to claim 1, characterized in that: The preparation method of the solder includes preparing powder solder by gas atomization or preparing strip solder by roller spinning; The gas atomization method for preparing powder solder includes the following steps: Weigh Ti, Ni, Zr and flux metal and reinforcement metal raw materials according to mass ratio, add them into a crucible, smelt them in a vacuum or inert environment, spray the smelted metal liquid through a nozzle at high speed to form metal droplets, cool, sieve and wash, and obtain the powder brazing material; The rollers are spun to prepare strip solder. The process includes: Metal raw materials including Ti, Ni, Zr, fluxing metal and reinforcing metal are weighed according to the mass ratio and added into a crucible, and smelted and homogenized in a vacuum or inert environment. The molten metal is degassed, and then the molten metal is poured onto the surface of a high-speed rotating roller to be quickly drawn into a thin strip and immediately cooled and rolled up to obtain the strip solder.

3. An application of the brazing filler metal as claimed in claim 1 in brazing of artificial dissimilar metal joints.

4. A method for brazing a brazing material in an artificial dissimilar metal joint as claimed in claim 1, characterized in that: The process includes: uniformly mixing the solder and the binder to prepare a solder paste; Evenly coating the solder paste on the to-be-welded portion of the metal joint; In an inert atmosphere or vacuum environment, slowly heat the to-be-welded portion of the metal joint to 350° C. to 700° C., and keep the temperature for 5 min to 120 min to remove the adhesive; Continue to heat the parts of the metal joints to be welded to 780℃~980℃ for welding, with a heating rate of 5℃ / min~20℃ / min. Keep warm for 5min~120min to ensure that the brazing material is fully melted. After welding is completed, cool with the furnace to complete the brazing of artificial dissimilar metal joints.

5. A brazing method for artificial dissimilar metal joints according to claim 4, characterized in that: The mass ratio of the solder to the binder is 0.4:1-3:1; the binder includes one of Nicrobraz Cements 320, NicrobrazCements 520, and s'binder binder.

6. A brazing method for artificial dissimilar metal joints according to claim 4, characterized in that: The thickness of the solder paste at the part to be welded is less than 0.2 mm.

7. The brazing method of artificial dissimilar metal joints according to claim 4, characterized in that: The inert atmosphere is an argon environment with an oxygen content of less than 1%; the vacuum degree of the vacuum environment is less than 1×10⁻ 3 Pa.

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