Welding flux for high-corrosion-resistance multi-layer composite board and welding process of welding flux

Abstract

The invention provides a welding flux for a high-corrosion-resistance multilayer composite board and a welding process of the welding flux. The welding flux comprises hollow silicon dioxide microsphere coated zinc filler, # imgabs0 # particles / SiC nanorods, Sn96.5 Ag3. 0Cu0.5 alloy powder, yttrium oxide stabilized zirconium oxide powder, titanium boride particles, rosin glyceride, ethylene glycol, polyethylene glycol, benzotriazole and aluminum oxide micro powder. The welding flux is prepared through multi-stage dispersion, mixing, drying, grinding, defoaming and extrusion molding and has excellent shear strength and corrosion resistance, and the welding process comprises the steps of adopting a Sn96.5 Ag3.0 Cu0.5 alloy welding wire for base layer submerged arc welding, adopting a nickel base alloy welding wire for transition layer pulse TIG welding and adopting the welding flux for multi-layer argon arc welding. Through the collaborative design of the nanostructure filler and the optimization process, the interface bonding strength of the welding flux is enhanced, and the welding quality and corrosion resistance of the composite board welding structure are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solder materials, and particularly relates to a solder for a highly corrosion-resistant multi-layer composite plate and a welding process thereof. Background Art

[0002] In high-end manufacturing fields such as petrochemical industry, offshore engineering, nuclear power equipment, and aerospace, multi-layer composite plates, as key materials, are widely used in structural components such as pressure vessels, heat exchangers, reaction kettles, and ship structures that need to be in high-corrosion and high-load environments for a long time. Their core advantage lies in achieving the synergistic improvement of mechanical properties and corrosion resistance by combining different functional layer materials. To ensure the safety and stability of the structure during long-term service, welding, as the key process for connecting multi-layer composite plates, the performance of its welding materials directly determines the overall reliability and service life of the weld area. Especially in complex and harsh environments, the solder not only needs to have good wettability and processability, but also needs to maintain excellent shear strength and corrosion resistance under variable working conditions such as high temperature, high humidity, and strong corrosion, so as to ensure the structural integrity and anti-failure ability of the welded joint. Therefore, developing special solders with high shear strength and high corrosion resistance and matching welding processes can not only improve the overall performance and service life of multi-layer composite plate structures, but also provide key material support for highly reliable connections under complex working conditions, which has important engineering significance and broad application prospects.

[0003] Although a large amount of research has been carried out in the field of welding materials and certain progress has been made, the existing solders for multi-layer composite plates still have obvious deficiencies in terms of shear strength and corrosion resistance. For example, Chinese Patent No. CN1398697A discloses a lead-free solder. Although it proposes a method to improve the welding effect through multi-component alloy powder, in actual applications, it still faces problems such as insufficient weld connection strength and decreased corrosion resistance, and it is difficult to meet the stability requirements in high-demand service environments. The key reason is that the multi-scale reinforcement mechanism has not been effectively introduced in the solder design, and the material microstructure lacks cooperative strengthening, resulting in weak bonding force at the welding interface and easy occurrence of local electrochemical reactions in the corrosion medium, further weakening its service performance. At the same time, some existing technical solutions only focus on the optimization of process parameters during the welding process, while ignoring the fundamental impact of the microstructure and composition regulation of the solder itself on performance, and it is difficult to achieve performance breakthroughs from the material essence level.

[0004] Therefore, those skilled in the art urgently need to systematically construct a new solder system with interface strengthening effect and corrosion inhibition ability from the perspective of the coordination of material composition and welding process to meet the dual requirements of shear strength and corrosion resistance under complex working conditions. Summary of the Invention

[0005] (1) Technical Problems to be Solved The object of the present invention is to provide a solder for highly corrosion-resistant multi-layer composite plates and its welding process, so as to solve the problems of insufficient shear strength and corrosion resistance of the existing solder.

[0006] (2) Technical solution In order to achieve the above object, the present invention provides the following technical solution: A solder for highly corrosion-resistant multi-layer composite plates, comprising the following raw materials by weight: 6.0 - 12.0 parts of hollow silica microsphere-coated zinc filler, 4.0 - 8.0 parts of [particle] / SiC nanorods, 90.0 - 110.0 parts of Sn96.5Ag3.0Cu0.5 alloy powder, 4.0 - 6.0 parts of yttria-stabilized zirconia powder, 2.0 - 5.0 parts of titanium boride particles, 15.0 - 25.0 parts of rosin glyceride, 8.0 - 12.0 parts of ethylene glycol, 3.0 - 5.0 parts of polyethylene glycol PEG-400, 0.5 - 1.5 parts of benzotriazole, 1.0 - 2.0 parts of alumina fine powder; The hollow silica microsphere-coated zinc filler is composed of porous hollow silica microspheres and metal zinc particles coated in the inner cavity of the porous hollow silica microspheres, and through-hole structures are uniformly distributed on the surface of the porous hollow silica microspheres; The [particle] / SiC nanorods are composed of SiC nanorods and [particle] loaded on the surface of the SiC nanorods. particles.

[0007] Further, the mass ratio of the porous hollow silica microspheres to the metal zinc particles is 1:0.8 - 1.5.

[0008] Further, the average diameter of the porous hollow silica microspheres is 0.5 - 2.0 μm, and the average diameter of the pores is 45 - 90 nm.

[0009] Further, the mass ratio of the SiC nanorods to the [particle] is 1:0.3 - 0.8.

[0010] Further, the average diameter of the SiC nanorods is 90 - 150 nm, the average length is 0.5 - 2.0 μm, and the dimensions of each direction of the [particle] are 10 - 28 nm.

[0011] Further, the preparation method of the hollow silica microsphere-coated zinc filler is as follows: by weight, 8.0 - 12.0 parts of porous hollow silica microspheres are dispersed in a mixed solvent composed of 20.0 - 30.0 parts of absolute ethanol and 5.0 - 8.0 parts of deionized water. After ultrasonic treatment for 20 - 40 min, a uniform dispersion liquid is obtained. A zinc nitrate solution with a concentration of 0.1 - 0.5 mol / L is added dropwise to the dispersion liquid, and the mass ratio of the added zinc nitrate solution to the porous hollow silica microspheres is controlled to be 1:0.6 - 1.2. Subsequently, stirring is continued at a stirring rate of 300 - 500 rpm for 0.5 - 2.0 h to allow zinc ions to penetrate into the cavities of the porous hollow silica microspheres through capillary action. The porous hollow silica microspheres loaded with zinc ions are collected by centrifugation at a centrifugation rate of 9000 - 12000 rpm and placed under a vacuum of -0.06 - -0.10 MPa and a temperature of 60 - 80 °C for rotary evaporation for 30 - 60 min to remove the solvent to obtain precursor A. The precursor A is placed in a reduction furnace and a mixed gas with a content of 5 - 10 vol% is introduced. It is heated to 350 - 400 °C at a heating rate of 2 - 5 °C / min and then kept warm for 1.0 - 3.0 h to complete the in-situ reduction of zinc ions. During the reduction process, the gas flow rate is maintained at 50 - 100 mL / min to ensure the uniformity of the reaction. Finally, after natural cooling to room temperature, the hollow silica microsphere-coated zinc filler is obtained.

[0012] Furthermore, the preparation method of the porous hollow silica microspheres is as follows: by weight, 15.0 - 20.0 parts of glucose are dissolved in 200 - 300 parts of deionized water to form a transparent solution, which is transferred to a polytetrafluoroethylene-lined autoclave with a filling rate of 35% - 45%, and hydrothermally reacted at 170 - 190 °C for 2.5 - 3.5 h. The carbon microspheres are collected by centrifugation at a centrifugal rate of 9000 - 11000 rpm, washed alternately with deionized water and absolute ethanol 3 - 6 times, and then dried at 75 - 85 °C for 5 - 7 h to obtain a carbon template. 1.0 - 1.5 parts of the carbon template are dispersed in a mixed solvent composed of 200 - 250 parts of absolute ethanol and 90 - 110 parts of deionized water, stirred at 400 - 500 rpm and ultrasonically treated for 25 - 35 min to form a suspension. After adding 1.8 - 2.2 parts of cetyltrimethylammonium bromide, the pH is adjusted to 9.5 - 10.5, and 9 - 11 parts of tetraethyl orthosilicate are added dropwise and continuously stirred at 400 - 500 rpm for 11 - 13 h to complete the hydrolysis and polycondensation reaction. After centrifuging to remove the supernatant, the precipitate is retained. After 3 - 5 cycles of centrifugation at a centrifugal rate of 9000 - 11000 rpm / absolute ethanol washing / re-dispersion treatment, it is dried at 75 - 85 °C for 11 - 13 h to obtain precursor B. Precursor B is placed in an air atmosphere and heated to 540 - 560 °C at a heating rate of 4 - 6 °C / min and then calcined for 3.5 - 4.5 h to remove the templating agent, obtaining the porous hollow silica microspheres.

[0013] It should be noted that the present invention uses hollow silica microspheres to coat zinc fillers, which enhances the shear strength and corrosion resistance of the solder. The core lies in constructing a composite reinforcement unit with integrated structural and functional characteristics through the synergistic effect of the porous structure and metallic zinc. Specifically, the porous hollow silica microspheres used have a highly controllable hollow structure and through channels. Their excellent specific surface area and pore distribution provide an ideal carrier for the effective loading of metallic zinc, and can uniformly introduce zinc precursors into the inner cavity of the microspheres through capillary action, and form a coating structure under a reducing atmosphere, thus realizing a composite configuration with synergistic inner encapsulation and outer shell at the microscale; the purpose of this structural design is to utilize the size stability and thermal insulation characteristics of the hollow microspheres to improve the structural integrity of the solder under high-temperature conditions, while endowing the solder with good metallic wettability and interfacial activity through the filling of zinc, which is beneficial to improving the bonding strength of the welded joint; during the actual welding process, the zinc particles in the coating structure can be released under appropriate conditions to form a metal connection channel with the base material, enhancing the interfacial bonding ability, while the porous hollow silica microspheres act as a microscopic skeleton to inhibit stress concentration and crack propagation, thereby increasing the shear strength; on the other hand, the microscopic heterogeneous structure formed by this composite filler in the welded joint helps to construct a multi-phase synergistic corrosion retardation system. The hollow structure itself has certain shielding characteristics, and the presence of zinc can form a sacrificial anode effect in a corrosive environment, further delaying the corrosion process in the weld area. In summary, the present invention effectively combines porous hollow silica microspheres with controllable structures and functional metallic zinc to form a novel composite filler, and without relying on additional alloying elements, effectively improves the shear strength and corrosion resistance of the solder, realizes the functional synergy of structural reinforcement and electrochemical protection, and provides a new design idea for the development of high-performance welding materials.

[0014] Furthermore, the The preparation method of the particles / SiC nanorods is as follows: by weight, disperse a total mixture of 5.0 - 8.0 parts of zinc salt and molybdate in a solvent system, where the molar ratio of zinc salt to molybdate is 1:0.98 - 1.02. The zinc salt is selected from zinc nitrate, and the molybdate is selected from sodium molybdate. Dissolve the total mixture in a mixed solvent composed of 50.0 - 70.0 parts of deionized water and 30.0 - 50.0 parts of absolute ethanol, and continuously stir at a stirring rate of 400 - 800 rpm for 20 - 40 min to fully complex the ions. Then add 1.0 - 3.0 parts of SiC nanorods and continue stirring for 10 - 20 min. Subsequently, gradually add ammonia water with a concentration of 0.1 - 0.5 mol / L to adjust the pH to 6.5 - 8.5, and carry out a coprecipitation reaction at a temperature of 60 - 90°C for 2.0 - 4.0 h to form a composite precursor C. Centrifuge the composite precursor C at a centrifugation rate of 10000 - 15000 rpm to remove the supernatant and retain the precipitate. Wash it alternately with deionized water and absolute ethanol for 3 - 6 times to remove unreacted salts and by-products. After drying the obtained product under a vacuum of -0.05 - -0.10 MPa and a temperature of 70 - 90°C for 6 - 10 h, heat it to 400 - 600°C at a heating rate of 3 - 8°C / min in a protective atmosphere and hold for 1.5 - 3.5 h to complete the phase transformation, and finally obtain particles / SiC nanorods.

[0015] Further, the preparation method of the SiC nanorods is as follows: by weight, mix 40.0 - 60.0 parts of tetraethyl orthosilicate, 30.0 - 50.0 parts of absolute ethanol, and 10.0 - 20.0 parts of deionized water, then add 1.0 - 5.0 parts of 60 - 65 wt% nitric acid, and carry out a hydrolysis reaction at a temperature of 30 - 50°C and a stirring rate of 300 - 600 rpm for 2.0 - 4.0 h to form a transparent solution. Then add 5.0 - 15.0 parts of glucose and introduce 0.5 - 3.0 parts of nickel nitrate as a catalyst, continue stirring for 1.0 - 3.0 h to form a homogeneous sol, and then let it stand for 12 - 36 h to complete the gelation process. Place the obtained wet gel under a vacuum of -0.05 - -0.08 MPa and a temperature of 60 - 80°C for 8 - 12 h to remove the solvent volatiles and obtain a dry gel precursor D. Place the dry gel precursor D in an argon atmosphere and heat it to 1200 - 1500°C at a heating rate of 5 - 10°C / min and hold for 2.0 - 4.0 h to cause a carbothermal reduction reaction between the silicon source and the carbon source to generate silicon carbide nanorods.

[0016] It should be noted that the present invention uses The particles / SiC nanorods also enhance the shear strength and corrosion resistance of the solder. The core lies in constructing a structural-functional composite unit at the nanoscale. By The particles are loaded on the surface of SiC nanorods to form a stable heterogeneous binding interface, realizing the synergistic effect of mechanical enhancement and chemical protection. Specifically, as a high-strength ceramic phase, SiC nanorods have good thermal stability and mechanical rigidity. In the solder, they can effectively inhibit plastic deformation and crack propagation induced by thermal stress, improving the structural density and shear resistance of the welding interface. At the same time, their one-dimensional rod-like structure helps to form a continuous reinforcement path in the solder system, promoting load transfer and microstress dispersion. The particles, as surface functional phases, are uniformly loaded on the SiC nanorods. Their stable metal oxide characteristics endow them with certain chemical inertness and shielding effects in corrosive media, and can form a microscale corrosion inhibition barrier in the welded joint, thus effectively slowing down the generation and diffusion of corrosion products. By realizing the ion complexation and deposition of zinc salts and molybdates during the coprecipitation process and combining subsequent heat treatment to induce phase transformation, the particles can stably adhere to the SiC surface, forming a tightly bound composite structure, effectively improving the interfacial compatibility and overall stability. This design utilizes the structural support of SiC and the interfacial passivation characteristics to further expand the multifunctional performance of the material on the basis of a single reinforcement mechanism. It not only strengthens the mechanical properties of the solder but also significantly improves its service reliability in complex corrosive environments, demonstrating the advantages of the coordinated regulation of material composition and microstructure.

[0017] Furthermore, the solder for the highly corrosion-resistant multi-layer composite board is prepared by the following steps: T1: Disperse hollow silica microsphere-coated zinc fillers in a mixed solvent composed of absolute ethanol and deionized water in a volume ratio of 2 - 3:1, and ultrasonic process for 20 - 40 min to form a uniform suspension. Add nanorods to the suspension, stir at a stirring rate of 400 - 600 rpm for 30 - 60 min, and control the system temperature at 25 - 30 °C to obtain a composite suspension system. T2: Add Sn96.5Ag3.0Cu0.5 alloy powder, yttria-stabilized zirconia powder, titanium boride particles, and alumina micropowder to the composite suspension system, and carry out ball milling and mixing under the conditions of a ball-to-material ratio of 5 - 10:1, a ball milling time of 60 - 120 min, and a temperature of 25 - 35 °C. Transfer the obtained mixture to a vacuum drying oven and dry it at a vacuum degree of -0.08 - 0.10 MPa and a temperature of 60 - 80 °C for 8 - 12 h to obtain a dry powder of the composite solder precursor. T3: Mix the dry powder of the composite solder precursor with glycerol ester of rosin, ethylene glycol, polyethylene glycol PEG-400, and benzotriazole, and stir for 20 - 40 min under the conditions of a stirring rate of 300 - 500 rpm and a temperature of 40 - 60 °C. Then, perform roll grinding on the obtained slurry under the conditions of a roll gap of 5 - 20 μm and a grinding times of 2 - 4 times to control the particle size and obtain a homogeneous slurry; T4: Extrude the homogeneous slurry through a strip-shaped forming die with a pore diameter of 1.0 - 3.0 mm under the conditions of an extrusion temperature of 80 - 120 °C and an extrusion pressure of 5 - 10 MPa to obtain a strip-shaped blank; T5: Transfer the strip-shaped blank to a vacuum degassing chamber, degas for 10 - 20 min under the conditions of a vacuum degree of -0.06 - 0.08 MPa and a temperature of 50 - 70 °C to remove internal bubbles and residual solvents. Then, send the degassed strip-shaped blank into a curing furnace, heat it to 150 - 180 °C at a heating rate of 5 - 8 °C / min under a nitrogen protection atmosphere, hold for 30 - 60 min, and then cool it to room temperature at a cooling rate of 2 - 4 °C / min to obtain the target solder.

[0018] The present invention also discloses a welding process for a highly corrosion-resistant multi-layer composite plate, including the following steps: S1: Mechanically polish, wipe with alcohol, and ultrasonically clean the surface of the workpiece to be welded in sequence to remove oil stains and oxide layers, control the surface roughness Ra to be 0.8 - 1.2 μm, the drying temperature to be 80 - 120 °C, and the drying time to be 10 - 15 min; Select the groove form according to the thickness of the base material. When the thickness ≤ 12 mm, use a type I groove; when the thickness > 12 mm, use a V-shaped groove. The groove angle is 60° - 70°, the root face thickness is 1.0 - 2.0 mm, and the root gap is 0.5 - 1.5 mm. After groove processing, confirm that the interface fitting rate ≥ 99% through ultrasonic testing; S2: Submerged arc welding is carried out on the base layer using Sn96.5Ag3.0Cu0.5 alloy welding wire. The wire diameter is 1.0 - 1.2 mm, the welding current is 150 - 220 A, the arc voltage is 22 - 28 V, the welding speed is 15 - 20 cm / min, the linear energy ≤ 20 kJ / cm, and the interlayer temperature ≤ 150 °C. Pulse TIG welding is carried out on the transition layer using nickel-based alloy welding wire. The welding current is 80 - 120 A, the arc length is 2 - 4 mm, the dilution rate < 15%, and the thickness of the transition layer is 1.5 - 2.0 mm. Argon arc welding is carried out on the clad layer using the solder for highly corrosion-resistant multi-layer composite plates mentioned above. The welding current is 100 - 150 A, the welding speed is 20 - 30 cm / min, and the thickness of the clad layer weld covers the transition layer by 0.5 - 1.0 mm. Before clad layer welding, polytetrafluoroethylene-based anti-spatter coating is applied within a range of 50 mm on both sides of the weld. The argon protection range covers the area 20 mm before and after the molten pool, and a trailing shield is set on the back to achieve an inert gas coverage rate ≥ 98%. Immediately after welding, copper backing contact forced cooling is adopted, the cooling rate ≥ 50 °C / s, the interlayer temperature is controlled such that the base layer ≤ 150 °C and the clad layer ≤ 80 °C, and segmental skip welding is used to reduce thermal stress; S3: The surface of the clad layer weld is mechanically polished to a roughness Ra ≤ 0.8 μm, and then passivated in a 5% - 10% citric acid solution for 30 - 60 min. The temperature of the passivation solution is 40 - 60 °C, the thickness of the passivation film is 0.2 - 0.5 μm, and the treated multi-layer composite plate is rinsed with deionized water and dried with nitrogen.

[0019] In the whole technical solution, the present invention significantly enhances the shear strength and corrosion resistance of the solder by designing and introducing a multi-component composite configuration. The core lies in the synergistic construction of zinc fillers coated with hollow silica microspheres and particles / SiC nanorods, combined with the synergistic dispersion of various reinforcing phases such as Sn96.5Ag3.0Cu0.5 alloy powder, yttria-stabilized zirconia powder, titanium boride particles, and alumina micro-powder, to form a composite solder system with multi-scale structure and multi-functional interface. Specifically, through ultrasonic dispersion and magnetic stirring techniques, zinc fillers coated with hollow silica microspheres and The particles / SiC nanorods form a stable suspension system in the mixed solvent, which effectively improves the uniform distribution of nanofillers in the solder, enhances the interaction interface between particles, and thus improves the microstructural stability and overall bonding strength of the solder; during the ball milling mixing process, the Sn96.5Ag3.0Cu0.5 alloy powder provides good wettability as the main metal phase of the welding, while the yttria-stabilized zirconia powder and alumina micropowder form a high-hardness ceramic reinforcement phase in the weld, which helps to improve the wear resistance and rigidity of the weld and inhibit thermal stress concentration; the introduction of titanium boride particles further improves the thermal stability and antioxidant ability of the solder, and cooperates with the anti-corrosion function of benzotriazole to build a multi-level corrosion barrier; in the process of slurry preparation and roller grinding, the particle size is further regulated and the interfacial activity is enhanced, providing an excellent fluidity and density foundation for subsequent extrusion molding and curing; inert atmosphere protection is used in the extrusion and curing stages to effectively avoid the oxidation reaction affecting the solder performance, and at the same time, the temperature and pressure control is used to ensure that the solder forms a dense and defect-free structure. In the welding process, the base layer welding uses Sn96.5Ag3.0Cu0.5 alloy welding wire to ensure the bonding quality of the metal matrix, the transition layer introduces nickel-based alloy welding wire to effectively buffer the thermal expansion difference between different metals, and the composite layer welding uses the solder obtained by the present invention for argon arc welding to achieve efficient fusion of the functional layer and the structural layer; after welding, mechanical polishing and citric acid passivation treatment are used to further improve the surface density and long-term corrosion resistance of the weld, forming a stable passivation film layer and improving the overall corrosion resistance. The design of the entire system gives full play to the composite synergistic effect of organic fillers, inorganic reinforcing phases and functional additives, so that the solder exhibits excellent performance in shear strength and corrosion resistance, and is suitable for the high-reliability welding needs of high-end multi-layer composite structures in complex and harsh environments.

[0020] (3) Beneficial technical effects 1. The present invention constructs a composite structure of hollow silica microspheres coated with zinc filler, which has both structural support and interface wetting properties, significantly improves the welding strength and corrosion resistance stability, solves the problems of low strength and easy corrosion of traditional solders, and has wide engineering applicability and irreplaceable synergistic advantages.

[0021] 2. Construction of the present invention The particle / SiC nanorod composite structure achieves synergistic improvement in mechanical strengthening and corrosion inhibition, significantly improves the stability of the welding interface, solves the problem of low strength and poor corrosion resistance of traditional solders, is suitable for the complex service environment in high-end equipment connections, and is unique and irreplaceable.

[0022] 3. The present invention constructs a composite solder system through the synergistic combination of multiple components, which significantly improves the shear strength and corrosion resistance of the weld, solves the problems of weak interface bonding and poor corrosion protection of traditional solders, is suitable for high-reliability connections under complex working conditions, and exhibits excellent structural stability and service durability. Description of the Drawings

[0023] Figure 1 This is the morphology diagram of the SiC nanorods prepared in Example 1 of the present invention.

[0024] Figure 2 This is the XRD phase analysis diagram of the SiC nanorods prepared in Example 1 of the present invention.

[0025] Figure 3 Prepared in Example 1 of the present invention Morphology diagram of particles / SiC nanorods.

[0026] Figure 4 Prepared in Example 1 of the present invention XRD phase analysis diagram of particles / SiC nanorods.

[0027] Figure 5 This is the morphology diagram of the porous hollow silica microspheres prepared in Example 1 of the present invention.

[0028] Figure 6 This is the XRD phase analysis diagram of the porous hollow silica microspheres prepared in Example 1 of the present invention.

[0029] Figure 7 This is the morphology diagram of the zinc filler coated with hollow silica microspheres prepared in Example 1 of the present invention.

[0030] Figure 8 This is the XRD phase analysis diagram of the zinc filler coated with hollow silica microspheres prepared in Example 1 of the present invention. Detailed Embodiments

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0032] Example 1 A solder for highly corrosion-resistant multi-layer composite plates includes the following raw materials in parts by weight: 6.0 parts of zinc filler coated with hollow silica microspheres, 4.0 parts of particles / SiC nanorods, 90.0 parts of Sn96.5Ag3.0Cu0.5 alloy powder, 4.0 parts of yttria-stabilized zirconia powder, 2.0 parts of titanium boride particles, 15.0 parts of rosin glyceride, 8.0 parts of ethylene glycol, 3.0 parts of polyethylene glycol PEG-400, 0.5 part of benzotriazole, and 1.0 part of alumina fine powder.

[0033] The described hollow silica microsphere-coated zinc filler is composed of porous hollow silica microspheres and metal zinc particles coated in the inner cavity of the porous hollow silica microspheres. The surface of the porous hollow silica microspheres is evenly distributed with a through-hole structure; the particle / SiC nanorod is composed of SiC nanorods and particles loaded on the surface of the SiC nanorods.

[0034] In this embodiment, the mass ratio of the porous hollow silica microspheres to the metal zinc particles is 1:0.8. Among them, the average diameter of the porous hollow silica microspheres is 0.5 μm, and the average diameter of the pores is 45 nm.

[0035] In this embodiment, the mass ratio of the SiC nanorods to the particles is 1:0.3. Among them, the average diameter of the SiC nanorods is 90 nm, and the average length is 0.5 μm. The dimensions of each

[0036] particle are 10 nm. with a mixed gas content of 5 vol%, heated at a rate of 2 °C / min to 350 °C and then held for 1.0 h to complete the in-situ reduction of zinc ions. During the reduction process, the gas flow rate was maintained at 50 mL / min to ensure the uniformity of the reaction. Finally, after natural cooling to room temperature, the hollow silica microsphere-coated zinc filler was obtained.

[0037] The preparation method of the porous hollow silica microspheres in this example is as follows: by weight, 15.0 parts of glucose are dissolved in 200 parts of deionized water to form a transparent solution, which is transferred to a polytetrafluoroethylene-lined autoclave with a filling rate of 35%, and hydrothermally reacted at 170 °C for 2.5 h. The carbon microspheres are collected by centrifugation at a rate of 9000 rpm, washed alternately with deionized water and absolute ethanol 3 times, and then dried at 75 °C for 5 h to obtain a carbon template. 1.0 part of the carbon template is dispersed in a mixed solvent composed of 200 parts of absolute ethanol and 90 parts of deionized water, and a suspension is formed by stirring at 400 rpm and ultrasonic treatment for 25 min. After adding 1.8 parts of cetyltrimethylammonium bromide, the pH is adjusted to 9.5, and 9 parts of tetraethyl orthosilicate are added dropwise and continuously stirred at 400 rpm for 11 h to complete the hydrolysis and polycondensation reaction. After centrifugation to remove the supernatant, the precipitate is retained. After 3 cycles of centrifugation at 9000 rpm / ethanol washing / redispersion treatment, it is dried at 75 °C for 11 h to obtain precursor B. Precursor B is placed in an air atmosphere and heated to 540 °C at a heating rate of 4 °C / min and then calcined for 3.5 h to remove the templating agent, obtaining porous hollow silica microspheres.

[0038] In this example The preparation method of the particles / SiC nanorods is as follows: by weight, a total mixture of 5.0 parts of zinc salt and molybdate is dispersed in a solvent system, where the molar ratio of zinc salt to molybdate is 1:0.98. The zinc salt is selected from zinc nitrate, and the molybdate is selected from sodium molybdate. The total mixture of the two salts is dissolved in a mixed solvent composed of 50.0 parts of deionized water and 30.0 parts of absolute ethanol to form a homogeneous solution. Subsequently, it is continuously stirred at a stirring rate of 400 rpm for 20 min to ensure sufficient ion complexation. Then 1.0 part of SiC nanorods is added and stirring continues for 10 min. Subsequently, ammonia water with a concentration of 0.1 mol / L is added dropwise to adjust the pH to 6.5, and a coprecipitation reaction is carried out at 60 °C for 2.0 h to form a composite precursor C. The composite precursor C is centrifuged at a rate of 10000 rpm to separate and remove the supernatant, and the precipitate is retained. It is washed alternately with deionized water and absolute ethanol 3 times to remove unreacted salts and by-products. The obtained product is dried at a vacuum of -0.05 MPa and a temperature of 70 °C for 6 h, and then heat-treated at a heating rate of 3 °C / min to 400 °C in a protective atmosphere for 1.5 h to complete the phase transformation, and finally obtain particles / SiC nanorods.

[0039] The preparation method of the SiC nanorods in this embodiment is as follows: by weight, 40.0 parts of tetraethyl orthosilicate, 30.0 parts of absolute ethanol, and 10.0 parts of deionized water are mixed and then 1.0 part of 65 wt% nitric acid is added. The hydrolysis reaction is carried out at a temperature of 30 °C and a stirring rate of 300 rpm for 2.0 h to form a transparent solution. Subsequently, 5.0 parts of glucose are added and 0.5 part of nickel nitrate is introduced as a catalyst, and stirring is continued for 1.0 h to form a homogeneous sol, which is then left standing for 12 h to complete the gelation process. The obtained wet gel is placed under a vacuum of -0.05 MPa and a temperature of 60 °C for 8 h to remove the solvent volatile components to obtain a dry gel precursor D. The dry gel precursor D is placed in an argon atmosphere and heated to 1200 °C at a heating rate of 5 °C / min, and then heat-treated for 2.0 h to cause a carbothermal reduction reaction between the silicon source and the carbon source to generate silicon carbide nanorods.

[0040] The solder for the highly corrosion-resistant multi-layer composite plate in this embodiment, its preparation method includes the following steps: T1: The hollow silica microsphere-coated zinc filler is dispersed in a mixed solvent composed of absolute ethanol and deionized water in a volume ratio of 2:1, and ultrasonic treatment is carried out at an ultrasonic power of 200 W and an ultrasonic frequency of 20 kHz for 20 min to form a uniform suspension; nanorods are added, and magnetic stirring is carried out at a stirring rate of 400 rpm for 30 min, and the system temperature is controlled at 25 °C to obtain a composite suspension system; T2: Sn96.5Ag3.0Cu0.5 alloy powder, yttria-stabilized zirconia powder, titanium boride particles, and alumina micro-powder are added to the composite suspension system, and planetary ball milling is carried out at a ball-to-material ratio of 5:1, a ball milling time of 60 min, and a temperature of 25 °C for mixing; the obtained mixture is transferred to a vacuum drying oven and dried at a vacuum of -0.08 MPa and a temperature of 60 °C for 8 h to obtain a dry powder of the composite solder precursor; T3: The dry powder of the composite solder precursor is mixed with rosin glyceride, ethylene glycol, polyethylene glycol PEG-400, and benzotriazole, and placed in a double planetary stirring device and stirred at a stirring rate of 300 rpm and a temperature of 40 °C for 20 min; the obtained slurry is subjected to particle size regulation by a three-roll mill with a roll gap of 5 μm and a grinding number of 2 times to obtain a homogeneous slurry; T4: The homogeneous slurry is injected into the barrel of a twin-screw extruder, and extruded through a strip-shaped forming die with a pore diameter of 1.0 mm at an extrusion temperature of 80 °C and an extrusion pressure of 5 MPa to obtain a strip-shaped blank; T5: Transfer the strip-shaped blank to a vacuum degassing chamber, degas for 10 min at a vacuum degree of -0.06 MPa and a temperature of 50 °C to remove internal bubbles and residual solvents; feed the degassed strip-shaped blank into a curing furnace, heat it to 150 °C at a heating rate of 5 °C / min under a nitrogen protection atmosphere and hold for 30 min, and then cool it to room temperature at a cooling rate of 2 °C / min to obtain the target solder.

[0041] Use the target solder obtained in this embodiment to weld a highly corrosion-resistant multi-layer composite plate, including the following steps: S1: Mechanically polish, wipe with alcohol, and ultrasonically clean the surface of the workpiece to be welded in sequence to remove oil stains and oxide layers, control the surface roughness Ra to be 0.8 μm, the drying temperature to be 80 °C, and the drying time to be 10 min; select the groove form according to the thickness of the base material. When the thickness ≤ 12 mm, use a type I groove. When the thickness > 12 mm, prepare a V-shaped groove with a groove angle of 60°, a root face thickness of 1.0 mm, and a root gap of 0.5 mm. After groove machining, confirm that the interface fitting rate ≥ 99% by ultrasonic testing; S2: Use a Sn96.5Ag3.0Cu0.5 alloy welding wire for submerged arc welding of the base layer. The welding wire diameter is 1.0 mm, the welding current is 150 A, the arc voltage is 22 V, the welding speed is 15 cm / min, the linear energy ≤ 20 kJ / cm, and the interlayer temperature ≤ 150 °C; use a nickel-based alloy welding wire for pulsed TIG welding of the transition layer. The welding current is 80 A, the arc length is 2 mm, the dilution rate < 15%, and the thickness of the transition layer is 1.5 mm; use the target solder obtained in this embodiment for argon arc welding of the clad layer. The welding current is 100 A, the welding speed is 20 cm / min, and the thickness of the clad layer weld covers the transition layer by 0.5 mm; apply a polytetrafluoroethylene-based anti-spatter coating within a range of 50 mm on both sides of the weld before clad layer welding. The argon protection range covers a 20-mm area before and after the molten pool, and a trailing shield is set on the back to achieve an inert gas coverage rate ≥ 98%; immediately use a copper backing contact forced cooling after welding, with a cooling rate ≥ 50 °C / s, and control the interlayer temperature to be ≤ 150 °C for the base layer and ≤ 80 °C for the clad layer. Use segmented skip welding to reduce thermal stress; S3: Mechanically polish the surface of the clad layer weld to a roughness Ra ≤ 0.8 μm, and then passivate it in a 5% citric acid solution for 30 min. The temperature of the passivation solution is 40 °C, the thickness of the passivation film is 0.2 μm. Rinse the treated multi-layer composite plate with deionized water and blow it dry with nitrogen.

[0042] According to Figures 1 to 8 the characterization results, it can be fully verified that the key functional components in Embodiment 1 of the present invention are successfully constructed and their structural characteristics. Figure 1It shows that the SiC nanorods prepared in this embodiment have a regular one-dimensional rod-like morphology, indicating good controllability in the precursor synthesis and growth process; Figure 2 The XRD pattern then confirms the crystal structure of the SiC nanorods, showing its distinct crystallization characteristics. Figure 3 It shows in The Figure 4 particles are uniformly loaded on the surface of the SiC nanorods, forming a typical heterostructure composite; The XRD pattern analysis further verifies the Figure 5 existence of the Figure 6 crystals, indicating its stable binding on the surface of the SiC nanorods. materials characteristics. Figure 7 It shows the multi-scale composite structure after the porous hollow silica microspheres prepared in this embodiment are successfully coated with metallic zinc, and the metallic zinc particles are tightly combined with the microspheres; Figure 8 The XRD pattern further confirms the existence of metallic zinc, and no other impurity phases are observed, indicating that the coating process maintains the structural integrity of zinc. The above morphology and phase analysis results corroborate each other, indicating that each component material is successfully synthesized according to the design, with clear structure and good dispersion, laying a solid material foundation for the performance improvement of the composite functional solder.

[0043] Example 2 A solder for highly corrosion-resistant multi-layer composite plates, comprising the following raw materials in parts by weight: 8.0 parts of hollow silica microspheres coated with zinc filler,

[0044] The hollow silica microspheres coated with zinc filler are composed of porous hollow silica microspheres and metallic zinc particles coated in the inner cavity of the porous hollow silica microspheres, and the surface of the porous hollow silica microspheres is uniformly distributed with through-hole structures; the particles / SiC nanorods are composed of SiC nanorods and ​​In this embodiment, the mass ratio of the porous hollow silica microspheres to the metallic zinc particles is 1:1.0. Among them, the average diameter of the porous hollow silica microspheres is 1.0 μm, and the average diameter of the pores is 59 nm.

[0045] In this embodiment, the mass ratio of the SiC nanorods to the particles is 1:0.5. Among them, the average diameter of the SiC nanorods is 108 nm, and the average length is 1.0 μm. The dimensions of each particle in all directions are 15 nm.

[0046] The preparation method of the hollow silica microspheres coated with zinc filler in this embodiment is as follows: by weight, 9.0 parts of porous hollow silica microspheres are dispersed in a mixed solvent composed of 23.0 parts of absolute ethanol and 6.0 parts of deionized water. After ultrasonic treatment for 26 min, the microspheres are uniformly dispersed. A zinc nitrate solution with a concentration of 0.2 mol / L is added dropwise to the dispersion liquid, and the mass ratio of the zinc nitrate solution to the porous hollow silica microspheres is controlled to be 1:0.8. Subsequently, stirring is continued at a stirring rate of 360 rpm for 1.0 h to allow zinc ions to penetrate into the cavities of the porous hollow silica microspheres through capillary action. After centrifugation at a centrifugation rate of 10,000 rpm, the unadsorbed residual solution is removed, and the porous hollow silica microspheres loaded with zinc ions are collected. The obtained product is placed under a vacuum of -0.07 MPa and at a temperature of 66 °C for rotary evaporation for 39 min to remove the solvent to obtain precursor A. The precursor A is placed in a reduction furnace and a mixed gas with a content of 7 vol% is introduced. It is heated to 365 °C at a heating rate of 3 °C / min and then held for 1.6 h to complete the in-situ reduction of zinc ions. During the reduction process, the gas flow rate is maintained at 65 mL / min to ensure the uniformity of the reaction. Finally, after natural cooling to room temperature, the hollow silica microspheres coated with zinc filler are obtained.

[0047] The preparation method of the porous hollow silica microspheres in this example is as follows: by weight, 17.0 parts of glucose are dissolved in 230 parts of deionized water to form a transparent solution, which is transferred to a polytetrafluoroethylene-lined autoclave with a filling rate of 38%, and hydrothermally reacted at 176 °C for 2.8 h. The carbon microspheres are collected by centrifugation at a rate of 9600 rpm, washed alternately with deionized water and absolute ethanol 4 times, and then dried at 78 °C for 6 h to obtain a carbon template. 1.2 parts of the carbon template are dispersed in a mixed solvent composed of 215 parts of absolute ethanol and 96 parts of deionized water, and a suspension is formed by stirring at 430 rpm and ultrasonic treatment for 28 min. After adding 1.9 parts of cetyltrimethylammonium bromide, the pH is adjusted to 9.8, and 10 parts of tetraethyl orthosilicate are added dropwise and continuously stirred at 430 rpm for 12 h to complete the hydrolysis and polycondensation reaction. After centrifuging to remove the supernatant, the precipitate is retained. After 4 cycles of centrifugation at 9600 rpm / absolute ethanol washing / re-dispersion treatment, it is dried at 78 °C for 12 h to obtain precursor B. Precursor B is placed in an air atmosphere and heated to 546 °C at a heating rate of 5 °C / min and then calcined for 3.8 h to remove the template agent, obtaining porous hollow silica microspheres.

[0048] In this example The preparation method of the particles / SiC nanorods is as follows: by weight, a total mixture of 5.0 parts of zinc salt and molybdate is dispersed in a solvent system, where the molar ratio of zinc salt to molybdate is 1:0.98. The zinc salt is selected from zinc nitrate, and the molybdate is selected from sodium molybdate. The total mixture of the two salts is dissolved in a mixed solvent composed of 50.0 parts of deionized water and 30.0 parts of absolute ethanol to form a homogeneous solution. Subsequently, it is continuously stirred at a stirring rate of 400 rpm for 20 min to ensure sufficient ion complexation. Then, 1.5 parts of SiC nanorods are added and stirring is continued for 15 min. Subsequently, ammonia water with a concentration of 0.1 mol / L is added dropwise to adjust the pH to 6.5, and a coprecipitation reaction is carried out at a temperature of 60 °C for 2.0 h to form a composite precursor C. The composite precursor C is centrifuged at a rate of 10000 rpm to separate and remove the supernatant, and the precipitate is retained. It is washed alternately with deionized water and absolute ethanol 3 times to remove unreacted salts and by-products. After the obtained product is dried at a vacuum degree of -0.05 MPa and a temperature of 70 °C for 6 h, it is heat-treated at a heating rate of 3 °C / min to 400 °C in a protective atmosphere for 1.5 h to complete the phase transformation, and finally obtain particles / SiC nanorods.

[0049] The preparation method of the SiC nanorods in this embodiment is as follows: by weight, 40.0 parts of tetraethyl orthosilicate, 30.0 parts of absolute ethanol, and 10.0 parts of deionized water are mixed and then 2.0 parts of 62 wt% nitric acid is added. A hydrolysis reaction is carried out at a temperature of 30 °C and a stirring rate of 300 rpm for 2.0 h to form a transparent solution. Subsequently, 5.0 parts of glucose is added and 0.5 part of nickel nitrate is introduced as a catalyst, and stirring is continued for 1.0 h to form a homogeneous sol, which is then left standing for 12 h to complete the gelation process. The obtained wet gel is placed under a vacuum of -0.05 MPa and a temperature of 60 °C for 8 h to remove the volatile solvent components to obtain a dry gel precursor D. The dry gel precursor D is placed in an argon atmosphere and heated to 1200 °C at a heating rate of 5 °C / min, followed by heat treatment for 2.0 h to cause a carbothermal reduction reaction between the silicon source and the carbon source to generate silicon carbide nanorods.

[0050] The solder for a highly corrosion-resistant multi-layer composite plate in this embodiment has a preparation method including the following steps: T1: The hollow silica microsphere-coated zinc filler is dispersed in a mixed solvent composed of absolute ethanol and deionized water in a volume ratio of 2:1, and ultrasonic treatment is carried out at an ultrasonic power of 200 W and an ultrasonic frequency of 20 kHz for 20 min to form a uniform suspension; nanorods are added, and stirring is carried out at a magnetic stirring rate of 400 rpm for 30 min, and the system temperature is controlled at 25 °C to obtain a composite suspension system; T2: Sn96.5Ag3.0Cu0.5 alloy powder, yttria-stabilized zirconia powder, titanium boride particles, and alumina micropowders are added to the composite suspension system, and mixing is carried out using a planetary ball mill at a ball-to-material ratio of 5:1, a ball milling time of 60 min, and a temperature of 25 °C; the obtained mixture is transferred to a vacuum drying oven and dried at a vacuum of -0.08 MPa and a temperature of 60 °C for 8 h to obtain a dry powder of the composite solder precursor; T3: The dry powder of the composite solder precursor is mixed with rosin glyceride, ethylene glycol, polyethylene glycol PEG-400, and benzotriazole, and placed in a double planetary stirring device and stirred at a stirring rate of 300 rpm and a temperature of 40 °C for 20 min; the obtained slurry is subjected to particle size regulation by a three-roll mill with a roll gap of 5 μm and a grinding number of 2 times to obtain a homogeneous slurry; T4: The homogeneous slurry is injected into the barrel of a twin-screw extruder, and extruded through a strip-shaped forming die with a pore diameter of 1.5 mm at an extrusion temperature of 120 °C and an extrusion pressure of 7 MPa to obtain a strip-shaped blank; T5: Transfer the strip-shaped blank to a vacuum degassing chamber, degas for 10 min at a vacuum degree of -0.06 MPa and a temperature of 60 °C to remove internal bubbles and residual solvents; send the degassed strip-shaped blank into a curing furnace, heat it to 150 °C at a heating rate of 5 °C / min under a nitrogen protection atmosphere and hold for 30 min, and then cool it to room temperature at a cooling rate of 2 °C / min to obtain the target solder.

[0051] Use the target solder obtained in this embodiment for welding a highly corrosion-resistant multi-layer composite plate, including the following steps: S1: Mechanically polish, wipe with alcohol, and ultrasonically clean the surface of the workpiece to be welded in sequence to remove oil stains and oxide layers, control the surface roughness Ra to be 0.8 μm, the drying temperature to be 80 °C, and the drying time to be 10 min; select the groove form according to the thickness of the base material, use a type I groove when the thickness ≤ 12 mm, prepare a V-shaped groove when the thickness > 12 mm, the groove angle is 60°, the root face thickness is 1.0 mm, the root gap is 0.5 mm, and after groove machining, confirm that the interface fitting rate ≥ 99% through ultrasonic testing; S2: Perform submerged arc welding on the base layer using a Sn96.5Ag3.0Cu0.5 alloy welding wire, the wire diameter is 1.0 mm, the welding current is 150 A, the arc voltage is 22 V, the welding speed is 15 cm / min, the linear energy ≤ 20 kJ / cm, and the interlayer temperature ≤ 150 °C; for the transition layer, perform pulsed TIG welding using a nickel-based alloy welding wire, the welding current is 80 A, the arc length is 2 mm, the dilution rate < 15%, and the thickness of the transition layer is 1.5 mm; for the clad layer, perform GTAW using the target solder obtained in this embodiment, the welding current is 100 A, the welding speed is 20 cm / min, and the thickness of the clad layer weld covers the transition layer by 0.5 mm; before clad layer welding, apply a polytetrafluoroethylene-based anti-spatter coating within a range of 50 mm on both sides of the weld, the argon protection range covers an area of 20 mm in front of and behind the molten pool, and a trailing shield is set on the back to achieve an inert gas coverage rate ≥ 98%; immediately after welding, perform contact forced cooling using a copper backing, the cooling rate ≥ 50 °C / s, and control the interlayer temperature to be ≤ 150 °C for the base layer and ≤ 80 °C for the clad layer, and use segmented skip welding to reduce thermal stress; S3: Mechanically polish the surface of the clad layer weld to a roughness Ra ≤ 0.8 μm, and then perform passivation treatment in a 5% citric acid solution for 30 min, the temperature of the passivation solution is 40 °C, the thickness of the passivation film is 0.2 μm, and the treated multi-layer composite plate is rinsed with deionized water and dried with nitrogen.

[0052] Example 3 A solder for a highly corrosion-resistant multi-layer composite plate, comprising the following raw materials in parts by weight: 10.0 parts of hollow silica microsphere-coated zinc filler, 6.0 parts of particles / SiC nanorods, 102.0 parts of Sn96.5Ag3.0Cu0.5 alloy powder, 5.0 parts of yttria-stabilized zirconia powder, 4.0 parts of titanium boride particles, 21.0 parts of glycerol ester of rosin, 10.0 parts of ethylene glycol, 4.0 parts of polyethylene glycol PEG-400, 1.1 parts of benzotriazole, 2.0 parts of alumina fine powder.

[0053] The hollow silica microsphere-coated zinc filler described above consists of porous hollow silica microspheres and metal zinc particles coated in the inner cavity of the porous hollow silica microspheres. The surface of the porous hollow silica microspheres is evenly distributed with through-hole structures; the Particles / SiC nanorods consist of SiC nanorods and particles loaded on the surface of the SiC nanorods.

[0054] In this embodiment, the mass ratio of the porous hollow silica microspheres to the metal zinc particles is 1:1.2. Among them, the average diameter of the porous hollow silica microspheres is 1.4 μm, and the average diameter of the pores is 72 nm.

[0055] In this embodiment, the mass ratio of the SiC nanorods to the particles is 1:0.6. Among them, the average diameter of the SiC nanorods is 126 nm, and the average length is 1.4 μm. The dimensions of each particle are 21 nm.

[0056] The preparation method of the hollow silica microsphere-coated zinc filler in this embodiment is as follows: by weight, 10.0 parts of porous hollow silica microspheres are dispersed in a mixed solvent composed of 26.0 parts of absolute ethanol and 7.0 parts of deionized water. After ultrasonic treatment for 32 min, the microspheres are evenly dispersed. A zinc nitrate solution with a concentration of 0.3 mol / L is added dropwise to the dispersion liquid, and the mass ratio of the zinc nitrate solution to the porous hollow silica microspheres is controlled to be 1:1.0. Subsequently, stirring is continued at a stirring rate of 420 rpm for 1.4 h to allow zinc ions to penetrate into the cavities of the porous hollow silica microspheres through capillary action. After centrifugation at a centrifugation rate of 10800 rpm, the unadsorbed residual solution is removed, and the porous hollow silica microspheres loaded with zinc ions are collected. The obtained product is placed under a vacuum of -0.08 MPa and a temperature of 72 °C for rotary evaporation for 48 min to remove the solvent to obtain precursor A. Precursor A is placed in a reduction furnace and a mixed gas with a content of 8 vol% is introduced. It is heated to 380 °C at a heating rate of 4 °C / min and then held for 2.0 h to complete the in-situ reduction of zinc ions. During the reduction process, the gas flow rate is maintained at 80 mL / min to ensure the uniformity of the reaction. Finally, after natural cooling to room temperature, the hollow silica microsphere-coated zinc filler is obtained.

[0057] The preparation method of the porous hollow silica microspheres in this example is as follows: By weight, 18.0 parts of glucose are dissolved in 260 parts of deionized water to form a transparent solution, which is transferred to a polytetrafluoroethylene-lined autoclave with a filling rate of 41%, and hydrothermally reacted at 182 °C for 3.1 h. The carbon microspheres are collected by centrifugation at a rate of 10,200 rpm, washed alternately with deionized water and absolute ethanol 4 times, and then dried at 81 °C for 6 h to obtain a carbon template. 1.3 parts of the carbon template are dispersed in a mixed solvent composed of 230 parts of absolute ethanol and 102 parts of deionized water, and a suspension is formed by stirring at 460 rpm and ultrasonic treatment for 31 min. After adding 2.0 parts of cetyltrimethylammonium bromide, the pH is adjusted to 10.1, and 10 parts of tetraethyl orthosilicate are added dropwise and continuously stirred at 460 rpm for 12 h to complete the hydrolysis and polycondensation reaction. After centrifuging to remove the supernatant, the precipitate is retained. After 4 cycles of centrifugation at a rate of 10,200 rpm / absolute ethanol washing / re-dispersion treatment, it is dried at 81 °C for 12 h to obtain precursor B. Precursor B is placed in an air atmosphere and heated to 552 °C at a heating rate of 5 °C / min and then calcined for 4.1 h to remove the template agent, obtaining porous hollow silica microspheres.

[0058] In this example The preparation method of the particles / SiC nanorods is as follows: By weight, a total mixture of 8.0 parts of zinc salt and molybdate is dispersed in a solvent system, where the molar ratio of zinc salt to molybdate is 1:1.02. The zinc salt is selected from zinc nitrate, and the molybdate is selected from sodium molybdate. The total mixture of the two salts is dissolved in a mixed solvent composed of 70.0 parts of deionized water and 50.0 parts of absolute ethanol to form a homogeneous solution. Subsequently, it is continuously stirred at a stirring rate of 800 rpm for 40 min to ensure sufficient ion complexation. Then, 2.5 parts of SiC nanorods are added and stirring continues for 18 min. Subsequently, ammonia water with a concentration of 0.5 mol / L is added dropwise to adjust the pH to 8.5, and a coprecipitation reaction is carried out at a temperature of 90 °C for 4.0 h to form a composite precursor C. The composite precursor C is centrifuged at a rate of 15,000 rpm to separate and remove the supernatant, and the precipitate is retained. It is washed alternately with deionized water and absolute ethanol 6 times to remove unreacted salts and by-products. The obtained product is dried at a vacuum degree of -0.10 MPa and a temperature of 90 °C for 10 h, and then heat-treated at a heating rate of 8 °C / min to 600 °C in a protective atmosphere for 3.5 h to complete the phase transformation, and finally obtain particles / SiC nanorods.

[0059] The preparation method of the SiC nanorods in this embodiment is as follows: by weight, 60.0 parts of tetraethyl orthosilicate, 50.0 parts of absolute ethanol, and 20.0 parts of deionized water are mixed and then 4.0 parts of 63 wt% nitric acid is added. A hydrolysis reaction is carried out at a temperature of 50 °C and a stirring rate of 600 rpm for 4.0 h to form a transparent solution. Subsequently, 15.0 parts of glucose are added and 3.0 parts of nickel nitrate are introduced as a catalyst, and stirring is continued for 3.0 h to form a homogeneous sol, which is then left standing for 36 h to complete the gelation process. The obtained wet gel is placed in a vacuum drying oven at a vacuum degree of -0.08 MPa and a temperature of 80 °C for 12 h to remove the solvent volatile components to obtain a dry gel precursor D. The dry gel precursor D is placed in an argon atmosphere and heated to 1500 °C at a heating rate of 10 °C / min, and then heat-treated for 4.0 h to cause a carbothermal reduction reaction between the silicon source and the carbon source to generate silicon carbide nanorods.

[0060] The solder for a highly corrosion-resistant multi-layer composite plate in this embodiment, its preparation method includes the following steps: T1: The hollow silica microsphere-coated zinc filler is dispersed in a mixed solvent composed of absolute ethanol and deionized water in a volume ratio of 3:1, and ultrasonic treatment is carried out at an ultrasonic power of 400 W and an ultrasonic frequency of 40 kHz for 40 min to form a uniform suspension; nanorods are added, and magnetic stirring is carried out at a stirring rate of 600 rpm for 60 min, and the system temperature is controlled at 30 °C to obtain a composite suspension system; T2: Sn96.5Ag3.0Cu0.5 alloy powder, yttria-stabilized zirconia powder, titanium boride particles, and alumina micropowder are added to the composite suspension system, and planetary ball milling is carried out at a ball-to-material ratio of 10:1, a ball milling time of 120 min, and a temperature of 35 °C for mixing; the obtained mixture is transferred to a vacuum drying oven and dried at a vacuum degree of -0.10 MPa and a temperature of 80 °C for 12 h to obtain a dry powder of the composite solder precursor; T3: The dry powder of the composite solder precursor is mixed with rosin glyceride, ethylene glycol, polyethylene glycol PEG-400, and benzotriazole, and placed in a double planetary stirring device and stirred at a stirring rate of 500 rpm and a temperature of 60 °C for 40 min; the obtained slurry is subjected to particle size regulation by a three-roll mill with a roll gap of 20 μm and a grinding number of 3 times to obtain a homogeneous slurry; T4: The homogeneous slurry is injected into the barrel of a twin-screw extruder, and extruded through a strip-shaped forming die with a pore diameter of 3.0 mm at an extrusion temperature of 100 °C and an extrusion pressure of 10 MPa to obtain a strip-shaped blank; T5: Transfer the strip-shaped blank to a vacuum degassing chamber, degas for 20 min at a vacuum degree of -0.08 MPa and a temperature of 70 °C to remove internal bubbles and residual solvents; send the degassed strip-shaped blank into a curing furnace, heat it to 180 °C at a heating rate of 8 °C / min under a nitrogen protection atmosphere, keep it warm for 60 min, and then cool it to room temperature at a cooling rate of 4 °C / min to obtain the target solder.

[0061] Use the target solder obtained in this example for welding a highly corrosion-resistant multi-layer composite plate, including the following steps: S1: Mechanically polish, wipe with alcohol, and ultrasonically clean the surface of the workpiece to be welded in sequence to remove oil stains and oxide layers, control the surface roughness Ra to be 1.2 μm, the drying temperature to be 120 °C, and the drying time to be 15 min; select the groove form according to the thickness of the base material. When the thickness ≤ 12 mm, use a type I groove. When the thickness > 12 mm, prepare a V-shaped groove with a groove angle of 70°, a blunt edge thickness of 2.0 mm, and a root gap of 1.5 mm. After groove machining, confirm that the interface fitting rate ≥ 99% by ultrasonic testing; S2: Use a Sn96.5Ag3.0Cu0.5 alloy welding wire for submerged arc welding of the base layer, with a welding wire diameter of 1.2 mm, a welding current of 220 A, an arc voltage of 28 V, a welding speed of 20 cm / min, a linear energy ≤ 20 kJ / cm, and an interlayer temperature ≤ 150 °C; use a nickel-based alloy welding wire for pulsed TIG welding of the transition layer, with a welding current of 120 A, an arc length of 4 mm, a dilution rate < 15%, and a transition layer thickness of 2.0 mm; use the target solder obtained in this example for argon arc welding of the clad layer, with a welding current of 150 A and a welding speed of 30 cm / min. The thickness of the clad layer weld covers the transition layer by 1.0 mm; apply a polytetrafluoroethylene-based anti-spatter coating within a range of 50 mm on both sides of the weld before clad layer welding. The argon protection range covers an area of 20 mm in front of and behind the molten pool, and a trailing shield is set on the back to achieve an inert gas coverage rate ≥ 98%; immediately use copper backing contact forced cooling after welding, with a cooling rate ≥ 50 °C / s, and control the interlayer temperature to be ≤ 150 °C for the base layer and ≤ 80 °C for the clad layer. Use segmented skip welding to reduce thermal stress; S3: Mechanically polish the surface of the clad layer weld to a roughness Ra ≤ 0.8 μm, and then perform passivation treatment in a 10% citric acid solution for 60 min at a passivation solution temperature of 60 °C and a passivation film thickness of 0.5 μm. Rinse the treated multi-layer composite plate with deionized water and blow it dry with nitrogen.

[0062] Example 4 A solder for a highly corrosion-resistant multi-layer composite plate, comprising the following raw materials in parts by weight: 12.0 parts of hollow silica microsphere-coated zinc filler, 8.0 parts of particles / SiC nanorods, 110.0 parts of Sn96.5Ag3.0Cu0.5 alloy powder, 6.0 parts of yttria-stabilized zirconia powder, 5.0 parts of titanium boride particles, 25.0 parts of rosin glyceride, 12.0 parts of ethylene glycol, 5.0 parts of polyethylene glycol PEG-400, 1.5 parts of benzotriazole, 2.0 parts of alumina fine powder.

[0063] The hollow silica microsphere-coated zinc filler described above is composed of porous hollow silica microspheres and metal zinc particles coated in the inner cavity of the porous hollow silica microspheres. The surface of the porous hollow silica microspheres is evenly distributed with a through-hole structure; the Particles / SiC nanorods are composed of SiC nanorods and particles loaded on the surface of the SiC nanorods.

[0064] In this embodiment, the mass ratio of the porous hollow silica microspheres to the metal zinc particles is 1:1.5. Among them, the average diameter of the porous hollow silica microspheres is 2.0 μm, and the average diameter of the pores is 90 nm.

[0065] In this embodiment, the mass ratio of the SiC nanorods to the particles is 1:0.8. Among them, the average diameter of the SiC nanorods is 150 nm, and the average length is 2.0 μm. The dimensions of each particle are 28 nm.

[0066] The preparation method of the hollow silica microsphere-coated zinc filler in this embodiment is as follows: By weight, 12.0 parts of porous hollow silica microspheres are dispersed in a mixed solvent composed of 30.0 parts of absolute ethanol and 8.0 parts of deionized water. After ultrasonic treatment for 40 min, the microspheres are evenly dispersed. A zinc nitrate solution with a concentration of 0.5 mol / L is added dropwise to the dispersion liquid, and the mass ratio of the zinc nitrate solution to the porous hollow silica microspheres is controlled to be 1:1.2. Subsequently, continuous stirring is carried out at a stirring rate of 500 rpm for 2.0 h to allow zinc ions to penetrate into the cavities of the porous hollow silica microspheres through capillary action. After centrifugation at a centrifugation rate of 12000 rpm, the unadsorbed residual solution is removed, and the porous hollow silica microspheres loaded with zinc ions are collected. The obtained product is placed under a vacuum of -0.10 MPa and a temperature of 80 °C for rotary evaporation for 60 min to remove the solvent to obtain precursor A. Precursor A is placed in a reduction furnace and a mixed gas with a content of 10 vol% is introduced. It is heated to 400 °C at a heating rate of 5 °C / min and then held for 3.0 h to complete the in-situ reduction of zinc ions. During the reduction process, the gas flow rate is maintained at 100 mL / min to ensure the uniformity of the reaction. Finally, after natural cooling to room temperature, the hollow silica microsphere-coated zinc filler is obtained.

[0067] The preparation method of the porous hollow silica microspheres in this example is as follows: By weight, 20.0 parts of glucose are dissolved in 300 parts of deionized water to form a transparent solution, which is transferred to a polytetrafluoroethylene-lined autoclave with a filling rate of 45%, and hydrothermally reacted at 190 °C for 3.5 h. The carbon microspheres are collected by centrifugation at a rate of 11000 rpm, washed alternately with deionized water and absolute ethanol 5 times, and then dried at 85 °C for 7 h to obtain a carbon template. 1.5 parts of the carbon template are dispersed in a mixed solvent composed of 250 parts of absolute ethanol and 110 parts of deionized water, and a suspension is formed by stirring at 500 rpm and ultrasonic treatment for 35 min. After adding 2.2 parts of cetyltrimethylammonium bromide, the pH is adjusted to 10.5, and 11 parts of tetraethyl orthosilicate are added dropwise and continuously stirred at 500 rpm for 13 h to complete the hydrolysis and polycondensation reaction. After centrifuging to remove the supernatant, the precipitate is retained. After 5 cycles of centrifugation at a rate of 11000 rpm / absolute ethanol washing / re-dispersion treatment, it is dried at 85 °C for 13 h to obtain precursor B. Precursor B is placed in an air atmosphere and heated to 560 °C at a heating rate of 6 °C / min and then calcined for 4.5 h to remove the template agent, obtaining porous hollow silica microspheres.

[0068] In this example The preparation method of the particles / SiC nanorods is as follows: By weight, a total mixture of 7.0 parts of zinc salt and molybdate is dispersed in a solvent system, where the molar ratio of zinc salt to molybdate is 1:1.00. The zinc salt is selected from zinc nitrate, and the molybdate is selected from sodium molybdate. The total mixture of the two salts is dissolved in a mixed solvent composed of 62.0 parts of deionized water and 42.0 parts of absolute ethanol to form a homogeneous solution. Subsequently, it is continuously stirred at a stirring rate of 640 rpm for 32 min to ensure sufficient ion complexation. Then 3.0 parts of SiC nanorods are added and stirring continues for 20 min. Subsequently, ammonia water with a concentration of 0.3 mol / L is added dropwise to adjust the pH to 7.7, and a coprecipitation reaction is carried out at a temperature of 78 °C for 3.0 h to form a composite precursor C. The composite precursor C is centrifuged at a rate of 13000 rpm to separate and remove the supernatant, and the precipitate is retained. It is washed alternately with deionized water and absolute ethanol 5 times to remove unreacted salts and by-products. After the obtained product is dried at a vacuum degree of -0.08 MPa and a temperature of 82 °C for 8 h, it is heat-treated at a heating rate of 6 °C / min to 520 °C in a protective atmosphere for 2.7 h to complete the phase transformation, and finally obtain particles / SiC nanorods.

[0069] The preparation method of the SiC nanorods in this embodiment is as follows: by weight, 52.0 parts of tetraethyl orthosilicate, 42.0 parts of absolute ethanol, and 16.0 parts of deionized water are mixed and then 5.0 parts of 60 wt% nitric acid is added. The hydrolysis reaction is carried out at a temperature of 42°C and a stirring rate of 480 rpm for 3.0 h to form a transparent solution. Subsequently, 11.0 parts of glucose is added and 2.0 parts of nickel nitrate is introduced as a catalyst, and stirring is continued for 2.0 h to form a homogeneous sol, which is then left standing for 26 h to complete the gelation process. The obtained wet gel is placed in a vacuum drying oven under a vacuum degree of -0.07 MPa and a temperature of 72°C for 10 h to remove the solvent volatile components to obtain a dry gel precursor D. The dry gel precursor D is placed in an argon atmosphere and heated to 1380°C at a heating rate of 8°C / min, and then heat-treated for 3.0 h to cause the carbon thermal reduction reaction between the silicon source and the carbon source to generate silicon carbide nanorods.

[0070] The solder for the highly corrosion-resistant multi-layer composite plate in this embodiment, its preparation method includes the following steps: T1: The hollow silica microsphere-coated zinc filler is dispersed in a mixed solvent composed of absolute ethanol and deionized water according to a volume ratio of 3:1, and ultrasonic treatment is carried out at an ultrasonic power of 320 W and an ultrasonic frequency of 32 kHz for 32 min to form a uniform suspension; subsequently, nanorods are added, and magnetic stirring is carried out at a stirring rate of 520 rpm for 48 min, and the system temperature is controlled at 28°C to obtain a composite suspension system; T2: Sn96.5Ag3.0Cu0.5 alloy powder, yttria-stabilized zirconia powder, titanium boride particles, and alumina micropowder are added to the composite suspension system, and mixing is carried out by a planetary ball mill at a ball-to-material ratio of 8:1, a ball milling time of 96 min, and a temperature of 31°C; the obtained mixture is transferred to a vacuum drying oven and dried at a vacuum degree of -0.09 MPa and a temperature of 72°C for 10 h to obtain a dry powder of the composite solder precursor; T3: The dry powder of the composite solder precursor is mixed with rosin glyceride, ethylene glycol, polyethylene glycol PEG-400, and benzotriazole, and placed in a double planetary stirring device and stirred at a stirring rate of 420 rpm and a temperature of 52°C for 32 min; the obtained slurry is subjected to particle size regulation by a three-roll grinder with a roll gap of 14 μm and a grinding number of 3 times to obtain a homogeneous slurry; T4: The homogeneous slurry is injected into the barrel of a twin-screw extruder, and extruded through a strip-shaped forming die with a pore diameter of 2.0 mm at an extrusion temperature of 104°C and an extrusion pressure of 8 MPa to obtain a strip-shaped blank; T5: Transfer the strip-shaped blank to a vacuum degassing chamber, and degas it for 16 min at a vacuum degree of -0.07 MPa and a temperature of 62 °C to remove internal bubbles and residual solvents; send the degassed strip-shaped blank into a curing furnace, and heat it from room temperature to 168 °C at a heating rate of 7 °C / min under a nitrogen protection atmosphere, then hold the temperature for 48 min, and subsequently cool it to room temperature at a cooling rate of 3 °C / min to obtain the target solder.

[0071] Use the target solder obtained in this example to weld a highly corrosion-resistant multi-layer composite plate, including the following steps: S1: Mechanically polish, wipe with alcohol, and ultrasonically clean the surface of the workpiece to be welded in sequence to remove oil stains and oxide layers, control the surface roughness Ra to be 1.0 μm, the drying temperature to be 104 °C, and the drying time to be 13 min; select the groove form according to the thickness of the base material. When the thickness ≤ 12 mm, use a type I groove. When the thickness > 12 mm, prepare a V-shaped groove. The groove angle is 66°, the root face thickness is 1.6 mm, and the root gap is 1.1 mm. After groove machining, confirm that the interface fitting rate ≥ 99% through ultrasonic testing; S2: Use a Sn96.5Ag3.0Cu0.5 alloy welding wire for submerged arc welding of the base layer. The wire diameter is 1.1 mm, the welding current is 192 A, the arc voltage is 26 V, the welding speed is 18 cm / min, the linear energy ≤ 20 kJ / cm, and the interlayer temperature ≤ 150 °C; use a nickel-based alloy welding wire for pulsed TIG welding of the transition layer. The welding current is 104 A, the arc length is 3 mm, the dilution rate < 15%, and the thickness of the transition layer is 1.8 mm; use the target solder obtained in this example for argon arc welding of the cladding layer. The welding current is 130 A, the welding speed is 26 cm / min, and the thickness of the cladding layer weld covers the transition layer by 0.8 mm; apply a polytetrafluoroethylene-based anti-spatter coating within a range of 50 mm on both sides of the weld before cladding layer welding. The argon protection range covers a 20 mm area in front of and behind the molten pool, and a trailing shield is set on the back to achieve an inert gas coverage rate ≥ 98%; immediately use a copper backing contact forced cooling after welding, the cooling rate ≥ 50 °C / s, and control the interlayer temperature to be ≤ 150 °C for the base layer and ≤ 80 °C for the cladding layer. Use segmented skip welding to reduce thermal stress; S3: Mechanically polish the surface of the cladding layer weld to a roughness Ra ≤ 0.8 μm, and then passivate it in an 8% citric acid solution for 48 min. The temperature of the passivation solution is 52 °C, the thickness of the passivation film is 0.4 μm. After treatment, rinse the multi-layer composite plate with deionized water and blow it dry with nitrogen.

[0072] Comparative Example 1 It is basically the same as Example 1, except that the porous hollow silica microspheres are not coated with zinc.

[0073] Comparative Example 2 It is basically the same as Example 1, except that Particles

[0074] Comparative Example 3 It is basically the same as Example 1, except that the concentration of the zinc nitrate solution in the zinc ion loading step is 0.05 mol / L.

[0075] Comparative Example 4 It is basically the same as Example 1, except that the reducing atmosphere content of the hollow silica microsphere-coated zinc precursor is 3 vol%.

[0076] Comparative Example 5 It is basically the same as Example 1, except that the molar ratio of zinc salt to molybdate in the synthesis of particles / SiC nanorods is 1:1.5.

[0077] Comparative Example 6 It is basically the same as Example 1, except that the heat treatment temperature of the particles / SiC nanorods is 650 °C.

[0078] Comparative Example 7 It is basically the same as Example 1, except that the addition amount of tetraethyl orthosilicate in the synthesis of porous hollow silica microspheres is 6 parts.

[0079] Comparative Example 8 It is basically the same as Example 1, except that the stirring temperature of the composite suspension system is 40 °C.

[0080] Comparative Example 9 It is basically the same as Example 1, except that the argon protection range of the cladding weld in the welding process only covers the 5 mm area before and after the molten pool.

[0081] Performance Test: Solder Joint Shear Strength Test: To quantify the interfacial bonding strength between the solder and the substrate aluminum, lap shear specimens (welding area 10×10 mm², substrate thickness 1.0 mm) were prepared in this experiment according to the ASTM D1002 standard. A universal testing machine was used to load the specimens at a rate of 1 mm / min until they broke, and the maximum shear force was recorded and the shear strength was calculated (τ = F / A). At least 5 parallel samples were tested in each group, and the average value was taken after excluding outliers.

[0082] Electrochemical Corrosion Kinetics Test: Based on ASTM G5, a three-electrode system (working electrode is the solder, reference electrode is the saturated calomel electrode, and auxiliary electrode is the platinum sheet) was used to test the potentiodynamic polarization curve and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution, and the corrosion current density (Icorr) and charge transfer resistance (Rct) were calculated by Tafel fitting.

[0083] Salt spray corrosion accelerated test (NSS method): To simulate the service corrosion behavior in marine or industrial environments, a neutral salt spray test can be conducted on the welded samples. Set a 5 wt% NaCl solution, a temperature of 35°C, and an exposure time of 48 - 168 hours. Observe the surface corrosion products and crack propagation. Conduct the test according to "GB / T 10125 - 2021 Salt Spray Test" to systematically evaluate the anti-corrosion durability of the composite solder in harsh environments.

[0084] The performance test results of the solders in Examples 1 - 4 and Comparative Examples 1 - 9 are shown in Table 1.

[0085]

[0086] As can be seen from Table 1, in the above solder systems, various structural designs and process parameters have a significant impact on the mechanical properties and corrosion resistance of the materials. The zinc-coated structure of the porous hollow silica microspheres helps to improve the dispersion and release efficiency of zinc, enhancing the sacrificial anode protection effect. Its absence will lead to an increase in the corrosion current density, a decrease in the charge transfer impedance, and an accelerated corrosion rate. The particles loaded on the surface of the SiC nanorods have a synergistic passivation ability and can form a stable protective film in the corrosion environment. The lack of this structure will weaken the overall protection efficiency. The loading concentration of zinc ions directly affects the zinc content and deposition uniformity. Too low a concentration will reduce the shear strength of the solder joints and deteriorate the corrosion resistance. The hydrogen content in the reducing atmosphere affects the zinc reduction efficiency and the quality of particle formation. Insufficient hydrogen may result in an uneven or non-dense zinc layer, thereby reducing the comprehensive performance. The molar ratio of zinc salt to molybdate during the synthesis process determines the phase composition and structural stability of the final product. An imbalance in the ratio will affect its electrochemical performance. The heat treatment temperature is an important factor for regulating the crystallinity and particle binding strength of the material. Too high a temperature may cause particle agglomeration or structural embrittlement, leading to an aggravated corrosion behavior. The structural uniformity of the porous microspheres is also affected by the amount of silicon source added, which in turn affects the stability of the composite dispersion system and the interfacial bonding strength. The stirring temperature is a key process parameter affecting the dispersion effect of the composite filler and the interfacial wettability. Insufficient temperature may result in uneven composition distribution. The coverage range of the protective atmosphere during the welding process directly affects the degree of oxidation in the molten pool area. If the protection is insufficient, it is easy to generate oxide inclusions or cracks, severely weakening the mechanical strength and corrosion resistance of the solder joints. In summary, the distribution and loading efficiency of zinc, the synergistic protection effect, multi-scale interface design, heat treatment regime, and welding atmosphere control are the key factors affecting the comprehensive performance of the composite solder of the present invention.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that any equivalent structural transformation made under the concept of the present invention by using the content of the specification and drawings of the present invention should be covered by the protection scope of the claims of the present invention.

Claims

1. A solder for a highly corrosion-resistant multilayer composite plate, characterized in that: The following raw materials are included by weight: 6.0-12.0 parts of hollow silica microspheres coated with zinc filler, 4.0-8.0 parts of particles / SiC nanorods, 90.0-110.0 parts of Sn96.5Ag3.0Cu0.5 alloy powder, 4.0-6.0 parts of yttria-stabilized zirconia powder, 2.0-5.0 parts of titanium boride particles, 15.0-25.0 parts of rosin glycerol ester, 8.0-12.0 parts of ethylene glycol, 3.0-5.0 parts of polyethylene glycol PEG-400, 0.5-1.5 parts of benzotriazole, and 1.0-2.0 parts of alumina micropowder; The hollow silica microsphere coated zinc filler is composed of porous hollow silica microspheres and metal zinc particles coated in the inner cavity of the porous hollow silica microspheres, and the surface of the porous hollow silica microspheres is uniformly distributed with through-hole structures; The Particles / SiC nanorods are composed of SiC nanorods and Particle composition.

2. The solder for the highly corrosion-resistant multi-layer composite plate according to claim 1, characterized in that: The mass ratio of the porous hollow silica microspheres to the metal zinc particles is 1:0.8-1.5; The average diameter of the porous hollow silica microspheres is 0.5-2.0 μm, and the average diameter of the pores is 45-90 nm.

3. The solder for the highly corrosion-resistant multi-layer composite plate according to claim 1, characterized in that: The SiC nanorods and The mass ratio of particles is 1:0.3~0.8; The average diameter of the SiC nanorods is 90-150 nm, the average length is 0.5-2.0 μm, and the The isotropic size of the particles is 10~28 nm.

4. The solder for a highly corrosion-resistant multilayer composite plate according to claim 1, characterized in that: The preparation method of the hollow silica microsphere coated zinc filler is as follows: by weight, 8.0-12.0 parts of porous hollow silica microspheres are dispersed in a mixed solvent consisting of 20.0-30.0 parts of anhydrous ethanol and 5.0-8.0 parts of deionized water, and a uniform dispersion is obtained after ultrasonic treatment for 20-40 min, and a zinc nitrate solution with a concentration of 0.1-0.5 mol / L is added dropwise to the dispersion, and the mass ratio of the added zinc nitrate solution to the porous hollow silica microspheres is controlled to be 1:0.6-1.2, and then the stirring rate is 300-500 rpm and the stirring is continued for 0.5-2.0 h to allow zinc ions to penetrate into the cavity of the porous hollow silica microspheres through capillary action, and the porous hollow silica microspheres loaded with zinc ions are collected by centrifugation at a centrifugal rate of 9000-12000 rpm, and placed in a vacuum chamber with a vacuum degree of -0.06--0.10 MPa, and a temperature of 60 to 80°C, and then the solvent is removed by rotary evaporation for 30 to 60 min to obtain precursor A. Precursor A is placed in a reduction furnace and passed through Content of 5~10 vol% The mixed gas was heated to 350-400°C at a heating rate of 2-5°C / min and then kept warm for 1.0-3.0 h to complete the in-situ reduction of zinc ions. During the reduction process, the gas flow rate was maintained at 50-100 mL / min to ensure the uniformity of the reaction. Finally, the hollow silica microspheres coated with zinc filler were obtained after natural cooling to room temperature.

5. The solder for the highly corrosion-resistant multi-layer composite plate according to claim 1, characterized in that: The preparation method of the porous hollow silica microspheres is as follows: by weight, 15.0-20.0 parts of glucose are dissolved in 200-300 parts of deionized water to form a transparent solution, which is transferred to a polytetrafluoroethylene-lined autoclave with a filling rate of 35%-45%, and hydrothermally reacted at 170-190°C for 2.5-3.5 hours, and the carbon microspheres are collected by centrifugation at a centrifugal rate of 9000-11000 rpm, and the carbon microspheres are washed alternately with deionized water and anhydrous ethanol for 3-6 times in sequence, and then dried at 75-85°C for 5-7 hours to obtain a carbon template, and 1.0-1.5 parts of the carbon template are dispersed in a mixed solvent consisting of 200-250 parts of anhydrous ethanol and 90-110 parts of deionized water, and stirred at 400-500 rpm and 25-35 min ultrasonic treatment to form a suspension, add 1.8-2.2 parts of hexadecyltrimethylammonium bromide and adjust the pH to 9.5-10.5, add 9-11 parts of tetraethyl orthosilicate dropwise and continue stirring at 400-500 rpm for 11-13 h to complete the hydrolysis and polycondensation reaction, remove the supernatant by centrifugation and retain the precipitate, and after 3-5 cycles of centrifugation at a centrifugal rate of 9000-11000 rpm / anhydrous ethanol washing / redispersion treatment, dry at 75-85°C for 11-13 h to obtain a precursor B, place the precursor B in an air atmosphere and heat it to 540-560°C at a heating rate of 4-6°C / min, and then calcine for 3.5-4.5 h to remove the template to obtain porous hollow silica microspheres.

6. The solder for the highly corrosion-resistant multi-layer composite plate according to claim 1, characterized in that: The The preparation method of particles / SiC nanorods is as follows: by weight, 5.0-8.0 parts of a total mixture of zinc salt and molybdate are dispersed in a solvent system, wherein the molar ratio of zinc salt to molybdate is 1:0.98-1.02, the zinc salt is selected from zinc nitrate, and the molybdate is selected from sodium molybdate, the total mixture is dissolved in a mixed solvent consisting of 50.0-70.0 parts of deionized water and 30.0-50.0 parts of anhydrous ethanol, stirring at a stirring rate of 400-800 rpm for 20-40 min to fully complex the ions, then 1.0-3.0 parts of SiC nanorods are added and stirring is continued for 10-20 min, then 0.1-0.5 mol / L ammonia water is added dropwise to adjust the pH to 6.5-8.5, and a coprecipitation reaction is carried out at a temperature of 60-90° C. for 2.0-4.0 h to form a composite precursor C, the composite precursor C is centrifuged at a centrifugal rate of 10000-15000 rpm to remove the supernatant and retain the precipitate, and is washed alternately with deionized water and anhydrous ethanol for 3-6 times to remove unreacted salts and by-products, the obtained product is dried under vacuum conditions of -0.05-0.10 MPa and a temperature of 70-90°C for 6-10 h, and then heated to 400-600°C at a heating rate of 3-8°C / min in a protective atmosphere and kept for 1.5-3.5 h to complete the crystal phase transformation, and finally Particles / SiC nanorods.

7. The solder for the highly corrosion-resistant multi-layer composite plate according to claim 1, characterized in that: The preparation method of the SiC nanorods is as follows: by weight, 40.0-60.0 parts of tetraethyl orthosilicate, 30.0-50.0 parts of anhydrous ethanol, and 10.0-20.0 parts of deionized water are mixed, and then 1.0-5.0 parts of 60-65wt% nitric acid are added, and a hydrolysis reaction is carried out for 2.0-4.0 hours at a temperature of 30-50°C and a stirring rate of 300-600 rpm to form a transparent solution, and then 5.0-15.0 parts of glucose are added and 0.5-3.0 parts of nickel nitrate are introduced as a catalyst, and stirring is continued for 1.0-3.0 hours to form a homogeneous sol, and then the sol is allowed to stand for 12-36 hours to complete the gelation process, and the obtained wet gel is placed in a vacuum degree of -0.05-0.08 MPa and a temperature of 60-80°C for 8-12 hours. h to remove the volatile components of the solvent to obtain a dry gel precursor D, which is placed in an argon atmosphere and heated to 1200-1500°C at a heating rate of 5-10°C / min, and then kept warm for 2.0-4.0 h to allow a carbothermal reduction reaction between the silicon source and the carbon source to occur to generate silicon carbide nanorods.

8. The solder for a highly corrosion-resistant multi-layer composite plate according to claim 1, characterized in that: Prepared by the following steps: T1: The hollow silica microspheres coated with zinc filler were dispersed in a mixed solvent consisting of anhydrous ethanol and deionized water in a volume ratio of 2-3:1, and ultrasonically treated for 20-40 min to form a uniform suspension. The nanorods were stirred at a stirring rate of 400-600 rpm for 30-60 min and the system temperature was controlled at 25-30°C to obtain a composite suspension system; T2: Add Sn96.5Ag3.0Cu0.5 alloy powder, yttria-stabilized zirconia powder, titanium boride particles and alumina powder to the composite suspension system, and perform ball milling at a ball-to-material ratio of 5-10:1, a ball milling time of 60-120 min, and a temperature of 25-35°C. Transfer the resulting mixture to a vacuum drying oven, and dry it for 8-12 h at a vacuum degree of -0.08-0.10 MPa and a temperature of 60-80°C to obtain a composite solder precursor dry powder; T3: The composite solder precursor dry powder is mixed with rosin glycerol ester, ethylene glycol, polyethylene glycol PEG-400 and benzotriazole, and stirred at a stirring rate of 300-500 rpm and a temperature of 40-60°C for 20-40 min. The resulting slurry is roller-milled at a roller gap of 5-20 μm and a grinding number of 2-4 times to control the particle size and obtain a homogeneous slurry; T4: Under the conditions of extrusion temperature of 80-120°C and extrusion pressure of 5-10 MPa, the homogenized slurry is extruded through a strip forming die with a pore size of 1.0-3.0 mm to obtain a strip blank; T5: The strip blank is transferred to a vacuum degassing chamber, and degassing is performed for 10 to 20 min at a vacuum degree of -0.06 to -0.08 MPa and a temperature of 50 to 70°C to remove internal bubbles and residual solvents. The degassed strip blank is sent to a curing furnace, and the temperature is raised to 150 to 180°C at a heating rate of 5 to 8°C / min under a nitrogen protective atmosphere, and then kept at this temperature for 30 to 60 min, and then cooled to room temperature at a cooling rate of 2 to 4°C / min to obtain the target solder.

9. A welding process for a highly corrosion-resistant multilayer composite plate, characterized in that: The following steps are involved: S1: The surface of the workpiece to be welded is subjected to mechanical grinding, alcohol wiping and ultrasonic cleaning in sequence to remove oil and oxide layer, and the surface roughness Ra is controlled to be 0.8~1.2 μm, the drying temperature is 80~120°C, and the drying time is 10~15 min; the groove form is selected according to the thickness of the parent material, and the I-shaped groove is used when the thickness is ≤12 mm, and the V-shaped groove is used when the thickness is greater than 12 mm. The groove angle is 60°~70°, the blunt edge thickness is 1.0~2.0 mm, and the root gap is 0.5~1.5 mm. After the groove is processed, ultrasonic testing is performed to confirm that the interface bonding rate is ≥99%; S2: Sn96.5Ag3.0Cu0.5 alloy welding wire is used for base submerged arc welding, the welding wire diameter is 1.0~1.2 mm, the welding current is 150~220 A, the arc voltage is 22~28 V, the welding speed is 15~20 cm / min, the line energy is ≤20 kJ / cm, and the interlayer temperature is ≤150°C; the transition layer is pulsed TIG welded with nickel-based alloy welding wire, the welding current is 80~120 A, the arc length is 2~4 mm, the dilution rate is <15%, and the thickness of the transition layer is 1.5~2.0 mm; the composite layer is argon arc welded with the solder described in any one of claims 1 to 8, the welding current is 100~150 A, the welding speed is 20~30 cm / min, and the thickness of the composite layer weld covers the transition layer by 0.5~1.0 mm; before the composite layer welding, polytetrafluoroethylene-based anti-splash coating is applied within 50 mm on both sides of the weld, and the argon protection range covers 20 mm area, a drag hood is set on the back to achieve an inert gas coverage rate of ≥98%; copper pad contact forced cooling is used immediately after welding, the cooling rate is ≥50°C / s, the interlayer temperature is controlled to be ≤150°C for the base layer and ≤80°C for the composite layer, and segmented jump welding is used to reduce thermal stress; S3: The surface of the composite weld is mechanically polished to a roughness of Ra ≤ 0.8 μm, and then passivated in a 5% to 10% citric acid solution for 30 to 60 min. The passivation solution temperature is 40 to 60 ° C, and the passivation film thickness is 0.2 to 0.5 μm. The treated multilayer composite plate is rinsed with deionized water and blown dry with nitrogen.

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