A solder for highly corrosion-resistant multi-layer composite plates and its welding process

Abstract

The present invention provides a solder for highly corrosion-resistant multi-layer composite plates and its welding process. The solder includes hollow silica microsphere-coated zinc fillers, particle / SiC nanorods, Sn96.5Ag3.0Cu0.5 alloy powder, yttria-stabilized zirconia powder, titanium boride particles, rosin glyceride, ethylene glycol, polyethylene glycol, benzotriazole, and alumina micropowder. It is prepared through multi-stage dispersion, mixing, drying, grinding, degassing, and extrusion molding, and has excellent shear strength and corrosion resistance. The welding process includes submerged arc welding for the base layer using Sn96.5Ag3.0Cu0.5 alloy welding wire, pulsed TIG welding for the transition layer using nickel-based alloy welding wire, and argon arc welding for the cladding layer using the solder of the present invention. Through the collaborative design of nanostructured fillers and optimized processes, the present invention enhances the interfacial bonding strength of the solder and significantly improves the welding quality and corrosion resistance of the welded structure of the composite plate.

Description

Technical Field

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

[0002] In high-end manufacturing fields such as petrochemical, ocean 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, reactors, 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 coordinated 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 zone. 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 strengthening mechanism has not been effectively introduced in the solder design, and the material microstructure lacks coordinated 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 optimizing the process parameters during welding, while ignoring the fundamental impact of the microstructure and composition regulation of the solder itself on the 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

[0006] 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.

[0007] (2) Technical solution

[0008] In order to achieve the above object, the present invention provides the following technical solution:

[0009] A solder for highly corrosion-resistant multi-layer composite plates includes the following raw materials in parts 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;

[0010] 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 evenly distributed on the surface of the porous hollow silica microspheres;

[0011] The [particle] / SiC nanorods are composed of SiC nanorods and [particle]s loaded on the surface of the SiC nanorods. particles.

[0012] Furthermore, the mass ratio of the porous hollow silica microspheres to the metal zinc particles is 1:0.8 - 1.5.

[0013] Furthermore, 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.

[0014] Furthermore, the mass ratio of the SiC nanorods to the particles is 1:0.3 - 0.8.

[0015] Furthermore, 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 of the particles are 10 - 28 nm.

[0016] 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 is obtained. 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. 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% of is introduced. It is heated to 350 - 400 °C at a heating rate of 2 - 5 °C / min and then held 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.

[0017] Further, 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, and a suspension is formed by stirring at 400 - 500 rpm and ultrasonic treatment for 25 - 35 min. 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 template agent, obtaining the porous hollow silica microspheres.

[0018] 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 the characteristics of integrated structure and function 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 the composite configuration of the synergism between the microscale inner package and the outer shell. The purpose of this structural design is to utilize the dimensional stability and thermal insulation characteristics of the hollow microspheres to improve the structural integrity of the solder under high-temperature conditions, and at the same time endow the solder with good metal wettability and interfacial activity by filling with 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 improving the shear strength. On the other hand, the microscopic heterogeneous structure formed by the composite filler in the welded joint helps to construct a multiphase synergistic corrosion retardation system. The hollow structure itself has certain shielding characteristics, and the presence of zinc can form a sacrificial anode effect in the corrosive environment, further delaying the corrosion process in the weld area. In summary, the present invention effectively combines the 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 synergism of structural enhancement and electrochemical protection, and provides a new design idea for the development of high-performance welding materials.

[0019] Furthermore, the The preparation method of the particles / SiC nanorods is as follows: by weight, 5.0 - 8.0 parts of the total mixture of zinc salt and molybdate are dispersed 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. The total mixture is dissolved 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 stirred 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 continues for 10 - 20 min. Subsequently, ammonia water with a concentration of 0.1 - 0.5 mol / L 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 centrifugation rate of 10000 - 15000 rpm to remove the supernatant and retain the precipitate, and alternately washed 3 - 6 times with deionized water and absolute ethanol to remove unreacted salts and by-products. After the obtained product is dried at a vacuum degree of -0.05 - -0.10 MPa and a temperature of 70 - 90 °C for 6 - 10 h, it is heated to 400 - 600 °C at a heating rate of 3 - 8 °C / min in a protective atmosphere and held for 1.5 - 3.5 h to complete the phase transformation, and finally obtain particles / SiC nanorods.

[0020] Furthermore, 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 absolute ethanol, and 10.0 - 20.0 parts of deionized water are mixed and then 1.0 - 5.0 parts of 60 - 65 wt% nitric acid are added. A hydrolysis reaction is carried out 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, 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 continues for 1.0 - 3.0 h to form a homogeneous sol and then left to stand for 12 - 36 h to complete the gelation process. The obtained wet gel is dried at a vacuum degree of -0.05 - -0.08 MPa and a temperature of 60 - 80 °C for 8 - 12 h to remove the solvent volatile matter to obtain a dry gel precursor D. The dry gel precursor D is placed in an argon atmosphere and heated to 1200 - 1500 °C at a heating rate of 5 - 10 °C / min and held 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.

[0021] 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 micro-stress dispersion. The particles, as surface functional phases, are uniformly loaded on the SiC nanorods. Their stable metal oxide properties endow them with certain chemical inertness and shielding effects in corrosive media, enabling the formation of micro-scale corrosion inhibition barriers in the welded joints, thereby effectively slowing down the generation and diffusion of corrosion products. By achieving ionic 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 interface compatibility and overall stability. This design utilizes the structural support of SiC and the interface 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.

[0022] Furthermore, the solder for the highly corrosion-resistant multi-layer composite plate is prepared through the following steps:

[0023] T1: Disperse hollow silica microspheres coated with zinc fillers in a mixed solvent composed of anhydrous ethanol and deionized water in a volume ratio of 2 - 3:1. After ultrasonic treatment for 20 - 40 min to form a uniform suspension, add nanorods, 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;

[0024] T2: Add Sn96.5Ag3.0Cu0.5 alloy powder, yttria-stabilized zirconia powder, titanium boride particles, and alumina micro-powder to the composite suspension system. Perform 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;

[0025] 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 at a stirring rate of 300 - 500 rpm and a temperature of 40 - 60 °C for 20 - 40 min. Perform roll grinding on the obtained slurry under the conditions of a roll gap of 5 - 20 μm and a grinding frequency of 2 - 4 times to control the particle size and obtain a homogeneous slurry.

[0026] T4: Under the conditions of an extrusion temperature of 80 - 120 °C and an extrusion pressure of 5 - 10 MPa, extrude the homogeneous slurry through a strip-shaped forming die with a pore diameter of 1.0 - 3.0 mm to obtain a strip-shaped blank.

[0027] 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. Feed 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.

[0028] The present invention also discloses a welding process for a highly corrosion-resistant multi-layer composite plate, including the following steps:

[0029] S1: Perform mechanical grinding, alcohol wiping, and ultrasonic cleaning on 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 machining, confirm through ultrasonic testing that the interface fitting rate ≥ 99%.

[0030] S2: The submerged arc welding for the base layer is carried out 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. The pulse TIG welding for the transition layer is carried out 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. The argon arc welding for the clad layer is carried out using the solder for the highly corrosion-resistant multi-layer composite plate 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 0.5 - 1.0 mm of the transition layer. Before the 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, and the cooling rate ≥ 50°C / s. The interlayer temperature is controlled such that the base layer ≤ 150°C and the clad layer ≤ 80°C. Sectional skip welding is adopted to reduce the thermal stress.

[0031] 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. After treatment, the multi-layer composite plate is rinsed with deionized water and dried with nitrogen.

[0032] 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 technology, 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.

[0033] (3) Beneficial technical effects

[0034] 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.

[0035] 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.

[0036] 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

[0037] Figure 1 This is the morphology diagram of the SiC nanorods prepared in Example 1 of the present invention.

[0038] Figure 2 This is the XRD phase analysis diagram of the SiC nanorods prepared in Example 1 of the present invention.

[0039] Figure 3 prepared in Example 1 of the present invention Morphology diagram of the particle / SiC nanorod

[0040] Figure 4 prepared in Example 1 of the present invention XRD phase analysis diagram of the particle / SiC nanorod

[0041] Figure 5 This is the morphology diagram of the porous hollow silica microspheres prepared in Example 1 of the present invention.

[0042] Figure 6 This is the XRD phase analysis diagram of the porous hollow silica microspheres prepared in Example 1 of the present invention.

[0043] Figure 7 This is the morphology diagram of the zinc filler coated with hollow silica microspheres prepared in Example 1 of the present invention.

[0044] 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

[0045] 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.

[0046] Example 1

[0047] A solder for a highly corrosion-resistant multi-layer composite plate includes the following raw materials in parts by weight: 6.0 parts of zinc filler coated with hollow silica microspheres, 4.0 parts of particle / SiC nanorod, 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.

[0048] The described zinc-filled hollow silica microspheres are 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 uniformly distributed with through-hole structures; the particle / SiC nanorods are composed of SiC nanorods and particles loaded on the surface of the SiC nanorods.

[0049] 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.

[0050] 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

[0051] particle are 10 nm. The preparation method of the zinc-filled hollow silica microspheres in this embodiment is as follows: By weight, 8.0 parts of porous hollow silica microspheres are dispersed in a mixed solvent composed of 20.0 parts of absolute ethanol and 5.0 parts of deionized water. After ultrasonic treatment for 20 min to uniformly disperse the microspheres, a zinc nitrate solution with a concentration of 0.1 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 1:0.6. Subsequently, continuous stirring is carried out at a stirring rate of 300 rpm for 0.5 h to allow zinc ions to penetrate into the cavities of the porous hollow silica microspheres through capillary action. After centrifugal separation at a centrifugal rate of 9000 rpm to remove the unadsorbed residual solution and collect the porous hollow silica microspheres loaded with zinc ions, the obtained product is placed under a vacuum of -0.06 MPa and a temperature of 60 °C for rotary evaporation for 30 min to remove the solvent to obtain precursor A. The precursor A is placed in a reduction furnace and a

[0052] mixed gas with a content of 5 vol% is introduced. It is heated to 350 °C at a heating rate of 2 °C / min and then held for 1.0 h to complete the in-situ reduction of zinc ions. During the reduction process, the gas flow rate is maintained at 50 mL / min to ensure the uniformity of the reaction. Finally, after natural cooling to room temperature, zinc-filled hollow silica microspheres are obtained.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 three 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 three cycles of centrifugation at 9000 rpm / absolute ethanol washing / re-dispersion 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 template agent, obtaining porous hollow silica microspheres.

[0053] 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 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 three times to remove unreacted salts and by-products. The obtained product is dried at a vacuum degree 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.

[0054] 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 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 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.

[0055] The solder for a highly corrosion-resistant multi-layer composite plate in this embodiment, its preparation method includes the following steps:

[0056] T1: Dispersing the hollow silica microsphere-coated zinc filler in a mixed solvent composed of absolute ethanol and deionized water in a volume ratio of 2:1, and carrying out ultrasonic treatment for 20 min at an ultrasonic power of 200 W and an ultrasonic frequency of 20 kHz to form a uniform suspension; adding nanorods, stirring at a magnetic stirring rate of 400 rpm for 30 min, and controlling the system temperature to 25°C to obtain a composite suspension system;

[0057] T2: Adding Sn96.5Ag3.0Cu0.5 alloy powder, yttria-stabilized zirconia powder, titanium boride particles, and alumina micro-powder to the composite suspension system, and mixing them 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; transferring the obtained mixture to a vacuum drying oven and drying it 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;

[0058] T3: Mixing the dry powder of the composite solder precursor with rosin glyceride, ethylene glycol, polyethylene glycol PEG-400, and benzotriazole, and placing it in a double planetary stirring device to stir at a stirring rate of 300 rpm and a temperature of 40°C for 20 min; regulating the particle size of the obtained slurry through a three-roll mill with a roll gap of 5 μm and a grinding number of 2 times to obtain a homogeneous slurry;

[0059] T4: Injecting the homogeneous slurry into the barrel of a twin-screw extruder, and extruding it through a strip-shaped forming die with a pore diameter of 1.0 mm under an extrusion temperature of 80°C and an extrusion pressure of 5 MPa to obtain a strip-shaped blank;

[0060] 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.

[0061] Use the target solder obtained in this example to weld the highly corrosion-resistant multi-layer composite plate, including the following steps:

[0062] 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;

[0063] S2: Use a Sn96.5Ag3.0Cu0.5 alloy welding wire for submerged arc welding of the base layer, with a welding wire diameter of 1.0 mm, a welding current of 150 A, an arc voltage of 22 V, a welding speed of 15 cm / min, a line 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 80 A, an arc length of 2 mm, a dilution rate < 15%, and a transition layer thickness of 1.5 mm; use the target solder obtained in this example for argon arc welding of the clad layer, with a welding current of 100 A and a welding speed of 20 cm / min. The thickness of the clad layer weld covers 0.5 mm of the transition layer; 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 in front of and behind the molten pool, and a drag shield is set on the back to achieve an inert gas coverage rate ≥ 98%; immediately after welding, use a copper backing contact forced cooling 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;

[0064] 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 at a passivation solution temperature of 40 °C and a passivation film thickness of 0.2 μm. Rinse the treated multi-layer composite plate with deionized water and dry it with nitrogen.

[0065] According to Figures 1 to 8 the characterization results, the successful construction of each key functional component and its structural characteristics in Example 1 of the present invention can be fully verified. 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 of Figure 3 confirmed the crystal structure of the SiC nanorods, showing its distinct crystallization characteristics. showed that Figure 4 particles were uniformly loaded on the surface of the SiC nanorods, forming a typical heterostructure composite; The XRD pattern analysis of Figure 5 further verified the existence of Figure 6 crystals, indicating its stable binding on the surface of the SiC nanorods. materials. Figure 7 It shows the multi-scale composite structure of the porous hollow silica microspheres prepared in this embodiment after successfully coating with metallic zinc, and the metallic zinc particles are tightly combined with the microspheres; Figure 8 The XRD pattern further confirmed the existence of metallic zinc, and no other impurity phases were observed, indicating that the coating process maintained the structural integrity of zinc. The above morphology and phase analysis results confirmed each other, indicating that each component material was successfully synthesized as designed, with clear structure and good dispersion, laying a solid material foundation for the performance improvement of the composite functional solder.

[0066] Example 2

[0067] A solder for highly corrosion-resistant multi-layer composite plates includes the following raw materials in parts by weight: 8.0 parts of zinc-coated hollow silica microspheres, particles / SiC nanorods 5.0 parts, 96.0 parts of Sn96.5Ag3.0Cu0.5 alloy powder, 5.0 parts of yttria-stabilized zirconia powder, 3.0 parts of titanium boride particles, 18.0 parts of rosin glyceride, 9.0 parts of ethylene glycol, 3.0 parts of polyethylene glycol PEG-400, 0.8 part of benzotriazole, and 1.0 part of alumina micropowder.

[0068] The zinc-coated hollow silica microspheres consist of porous hollow silica microspheres and metallic zinc particles coated in the inner cavity of the porous hollow silica microspheres. The surface of the porous hollow silica microspheres is uniformly distributed with through-hole structures; the particles / SiC nanorods consist of SiC nanorods and particles loaded on the surface of the SiC nanorods;

[0069] 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.

[0070] 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.

[0071] 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 a temperature of 66 °C and rotary evaporated 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.

[0072] 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 / ethanol washing / redispersion 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.

[0073] 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 continues 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 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.

[0074] 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 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.

[0075] The solder for the highly corrosion-resistant multi-layer composite plate in this embodiment, its preparation method includes the following steps:

[0076] T1: Dispersing the hollow silica microsphere-coated zinc filler in a mixed solvent composed of absolute ethanol and deionized water in a volume ratio of 2:1, and performing ultrasonic treatment for 20 min under the conditions of an ultrasonic power of 200 W and an ultrasonic frequency of 20 kHz to form a uniform suspension; adding nanorods, stirring at a magnetic stirring rate of 400 rpm for 30 min, and controlling the system temperature at 25 °C to obtain a composite suspension system;

[0077] T2: Adding Sn96.5Ag3.0Cu0.5 alloy powder, yttria-stabilized zirconia powder, titanium boride particles, and alumina micro-powder to the composite suspension system, and mixing 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; transferring the obtained mixture to a vacuum drying oven and drying 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;

[0078] T3: Mixing the dry powder of the composite solder precursor with rosin glyceride, ethylene glycol, polyethylene glycol PEG-400, and benzotriazole, and placing it in a double planetary stirring device to stir at a stirring rate of 300 rpm and a temperature of 40 °C for 20 min; regulating the particle size of the obtained slurry through a three-roll grinder with a roll gap of 5 μm and a grinding times of 2 times to obtain a homogeneous slurry;

[0079] T4: Injecting the homogeneous slurry into the barrel of a twin-screw extruder, and extruding it through a strip-shaped forming die with a pore diameter of 1.5 mm under the conditions of an extrusion temperature of 120 °C and an extrusion pressure of 7 MPa to obtain a strip-shaped blank;

[0080] 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.

[0081] 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;

[0082] S2: Use a Sn96.5Ag3.0Cu0.5 alloy welding wire for submerged arc welding of the base layer, 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 line 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 cladding layer, the welding current is 100 A, the welding speed is 20 cm / min, and the thickness of the cladding layer weld covers the transition layer by 0.5 mm; apply a polytetrafluoroethylene-based anti-spatter coating in a range of 50 mm on both sides of the weld before cladding 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 after welding, use a copper backing pad for contact forced cooling, 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, and use segmented skip welding to reduce thermal stress;

[0083] S3: Mechanically polish the surface of the cladding layer weld to a roughness Ra ≤ 0.8 μm, and then passivate it in a 5% citric acid solution for 30 min, the passivation solution temperature 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.

[0084] Example 3

[0085] 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.

[0086] 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 consist of SiC nanorods and Particles loaded on the surface of the SiC nanorods.

[0087] 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.

[0088] 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, the average length is 1.4 μm, The dimensions of each particle are 21 nm.

[0089] 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, continuous stirring is carried out 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 With a content of 8 vol% of A mixed gas, 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.

[0090] 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 / 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.

[0091] 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 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. After the obtained product is dried at a vacuum degree of -0.10 MPa and a temperature of 90 °C for 10 h, it is 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.

[0092] 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. 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 is added and 3.0 parts of nickel nitrate is introduced as a catalyst, and stirring is continued for 3.0 h to form a homogeneous sol, and then it is left standing for 36 h to complete the gelation process. The obtained wet gel is placed under a vacuum 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.

[0093] The solder for the highly corrosion-resistant multi-layer composite plate in this embodiment, its preparation method includes the following steps:

[0094] 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 400 W and an ultrasonic frequency of 40 kHz for 40 min to form a uniform suspension; Add nanorods, stir at a magnetic stirring rate of 600 rpm for 60 min, and control the system temperature at 30 °C to obtain a composite suspension system;

[0095] T2: Add Sn96.5Ag3.0Cu0.5 alloy powder, yttria-stabilized zirconia powder, titanium boride particles and alumina micropowder to the composite suspension system, and mix them by a planetary ball mill at a ball-to-material ratio of 10:1, a ball milling time of 120 min, and a temperature of 35 °C; Transfer the obtained mixture to a vacuum drying oven, and dry it at a vacuum of -0.10 MPa and a temperature of 80 °C for 12 h to obtain a dry powder of the composite solder precursor;

[0096] T3: Mix the dry powder of the composite solder precursor with rosin glyceride, ethylene glycol, polyethylene glycol PEG-400 and benzotriazole, and place it in a double planetary stirring device to stir at a stirring rate of 500 rpm and a temperature of 60 °C for 40 min; Adjust the particle size of the obtained slurry by a three-roll grinder with a roll gap of 20 μm and a grinding times of 3 times to obtain a homogeneous slurry;

[0097] T4: Inject the homogeneous slurry into the barrel of a twin-screw extruder, and extrude it through a strip-shaped forming die with a pore diameter of 3.0 mm under an extrusion temperature of 100 °C and an extrusion pressure of 10 MPa to obtain a strip-shaped blank;

[0098] 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 up to 180 °C at a heating rate of 8 °C / min under a nitrogen protection atmosphere, hold for 60 min, and then cool it to room temperature at a cooling rate of 4 °C / min to obtain the target solder.

[0099] Use the target solder obtained in this embodiment for welding a highly corrosion-resistant multi-layer composite plate, including the following steps:

[0100] S1: Perform mechanical grinding, alcohol wiping, and ultrasonic cleaning on 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 root face thickness of 2.0 mm, and a root gap of 1.5 mm. After groove machining, confirm that the interface fitting rate ≥ 99% through ultrasonic testing;

[0101] 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 embodiment for argon arc welding of the cladding layer, with a welding current of 150 A and a welding speed of 30 cm / min. The thickness of the cladding layer weld covers 1.0 mm of the transition layer; 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 after welding, use a copper backing pad for contact forced cooling, 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 cladding layer. Use segmented skip welding to reduce thermal stress;

[0102] S3: Mechanically polish the surface of the cladding 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 dry it with nitrogen.

[0103] Example 4

[0104] 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 [particle] / 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, and 2.0 parts of alumina fine powder.

[0105] 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. The surface of the porous hollow silica microspheres is evenly distributed with a through-hole structure; the [particle] / SiC nanorods are composed of SiC nanorods and [particle]s loaded on the surface of the SiC nanorods.

[0106] In this example, 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.

[0107] In this example, the mass ratio of the SiC nanorods to the [particle]s 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 various dimensions of the [particle]s are 28 nm.

[0108] The preparation method of the hollow silica microsphere-coated zinc filler in this example is as follows: In parts by weight, disperse 12.0 parts of porous hollow silica microspheres 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 to uniformly disperse the microspheres, gradually add a zinc nitrate solution with a concentration of 0.5 mol / L to the dispersion liquid and control the mass ratio of the zinc nitrate solution to the porous hollow silica microspheres to be 1:1.2. Subsequently, continuously stir at a stirring rate of 500 rpm for 2.0 h to allow zinc ions to penetrate into the cavity of the porous hollow silica microspheres through capillary action. Centrifuge at a centrifugation rate of 12000 rpm to remove the unadsorbed residual solution and collect the porous hollow silica microspheres loaded with zinc ions. Place the obtained product under a vacuum of -0.10 MPa and a temperature of 80 °C and rotate evaporate for 60 min to remove the solvent to obtain precursor A. Place precursor A in a reduction furnace and introduce with a content of 10 vol% of ​​The mixed gas was 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 was maintained at 100 mL / min to ensure the uniformity of the reaction. Finally, after natural cooling to room temperature, hollow silica microspheres coated with zinc filler were obtained.

[0109] The preparation method of the porous hollow silica microspheres in this example is as follows: By weight, 20.0 parts of glucose were dissolved in 300 parts of deionized water to form a transparent solution, which was 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 were 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 were dispersed in a mixed solvent composed of 250 parts of absolute ethanol and 110 parts of deionized water, and a suspension was formed by stirring at 500 rpm and ultrasonic treatment for 35 min. After adding 2.2 parts of cetyltrimethylammonium bromide, the pH was adjusted to 10.5, and 11 parts of tetraethyl orthosilicate were added dropwise and continuously stirred at 500 rpm for 13 h to complete the hydrolysis and polycondensation reaction. After centrifugation to remove the supernatant, the precipitate was retained. After 5 cycles of centrifugation at a rate of 11000 rpm / absolute ethanol washing / re-dispersion treatment, it was dried at 85 °C for 13 h to obtain precursor B. Precursor B was 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.

[0110] 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 was dispersed in a solvent system, where the molar ratio of zinc salt to molybdate was 1:1.00. The zinc salt was selected from zinc nitrate, and the molybdate was selected from sodium molybdate. The total mixture of the two salts was 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 was continuously stirred at a stirring rate of 640 rpm for 32 min to ensure sufficient ion complexation. Then, 3.0 parts of SiC nanorods were added and stirring continued for 20 min. Subsequently, ammonia water with a concentration of 0.3 mol / L was added dropwise to adjust the pH to 7.7, and a coprecipitation reaction was carried out at a temperature of 78 °C for 3.0 h to form a composite precursor C. The composite precursor C was centrifuged at a rate of 13000 rpm to separate and remove the supernatant, and the precipitate was retained. It was washed alternately with deionized water and absolute ethanol 5 times to remove unreacted salts and by-products. The obtained product was dried at a vacuum degree of -0.08 MPa and a temperature of 82 °C for 8 h, and then 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 obtained particles / SiC nanorods.

[0111] 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 60wt% 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 and 2.0 parts of nickel nitrate are introduced as a catalyst, and stirring is continued for 2.0 h to form a homogeneous sol, which is then allowed to stand for 26 h to complete the gelation process. The obtained wet gel is placed in a vacuum dryer at 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 a carbothermal reduction reaction between the silicon source and the carbon source to generate silicon carbide nanorods.

[0112] The solder for the highly corrosion-resistant multi-layer composite plate in this embodiment, its preparation method includes the following steps:

[0113] 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 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;

[0114] 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 8:1, a ball milling time of 96 min, and a temperature of 31°C for mixing; 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;

[0115] 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;

[0116] 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;

[0117] T5: Transfer the strip-shaped blank to a vacuum degassing chamber, and degas for 16 min at a vacuum degree of -0.07 MPa and a temperature of 62 °C to remove internal bubbles and residual solvents; Feed the degassed strip-shaped blank into a curing furnace, heat it up to 168 °C at a heating rate of 7 °C / min under a nitrogen protection atmosphere, hold for 48 min, and then cool it to room temperature at a cooling rate of 3 °C / min to obtain the target solder.

[0118] 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 1.0 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 with a groove angle of 66°, a root face thickness of 1.6 mm, and a root gap of 1.1 mm. After groove machining, confirm through ultrasonic testing that the interface fitting rate ≥ 99%;

[0119] S2: Use a Sn96.5Ag3.0Cu0.5 alloy welding wire for submerged arc welding of the base layer, with a welding wire diameter of 1.1 mm, a welding current of 192 A, an arc voltage of 26 V, a welding speed of 18 cm / min, a line 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 104 A, an arc length of 3 mm, a dilution rate < 15%, and a transition layer thickness of 1.8 mm; Use the target solder obtained in this example for argon arc welding of the cladding layer, with a welding current of 130 A and a welding speed of 26 cm / min. The thickness of the cladding layer weld covers the transition layer by 0.8 mm; Before cladding 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 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 after welding, use a copper backing pad for contact forced cooling, 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 cladding layer. Use segmented skip welding to reduce thermal stress;

[0120] S3: Mechanically polish the surface of the cladding layer weld to a roughness Ra ≤ 0.8 μm, and then perform passivation treatment in an 8% citric acid solution for 48 min at a passivation solution temperature of 52 °C and a passivation film thickness of 0.4 μm. Rinse the treated multi-layer composite plate with deionized water and dry it with nitrogen.

[0121] Comparative Example 1

[0122] It is basically the same as Example 1, except that the porous hollow silica microspheres are not coated with zinc.

[0123] Comparative Example 2

[0124] It is basically the same as Example 1, except that particles are not prepared on the surface of the SiC nanorods. Particles.

[0125] Comparative Example 3

[0126] 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.

[0127] Comparative Example 4

[0128] It is basically the same as Example 1, except that the content of the reducing atmosphere for coating the zinc precursor with hollow silica microspheres is 3 vol%. Content is 3 vol%.

[0129] Comparative Example 5

[0130] 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.

[0131] Comparative Example 6

[0132] It is basically the same as Example 1, except that the heat treatment temperature of the particles / SiC nanorods is 650 °C.

[0133] Comparative Example 7

[0134] It is basically the same as Example 1, except that the amount of tetraethyl orthosilicate added in the synthesis of porous hollow silica microspheres is 6 parts.

[0135] Comparative Example 8

[0136] It is basically the same as Example 1, except that the stirring temperature of the composite suspension system is 40 °C.

[0137] Comparative Example 9

[0138] It is basically the same as Example 1, except that in the welding process, the argon protection range of the clad layer weld only covers the 5 mm area before and after the molten pool.

[0139] Performance Test:

[0140] 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 fractured, 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.

[0141] Electrochemical corrosion kinetics test: Based on ASTM G5, a three-electrode system (the working electrode is the solder, the reference electrode is the saturated calomel electrode, and the auxiliary electrode is the platinum sheet) is used to test the potentiodynamic polarization curve and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. The corrosion current density (Icorr) and charge transfer resistance (Rct) are calculated by Tafel fitting.

[0142] Salt spray corrosion acceleration test (NSS method): To simulate the service corrosion behavior in marine or industrial environments, the welded samples can be subjected to a neutral salt spray test. 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.

[0143] The performance test results of the solders in Examples 1 - 4 and Comparative Examples 1 - 9 are shown in Table 1.

[0144]

[0145] As can be seen from Table 1, in the above solder system, various structural designs and process parameters have a significant impact on the mechanical properties and corrosion resistance of the material. The zinc-coated structure of the porous hollow silica microspheres helps to improve the dispersion and release efficiency of zinc, enhance the sacrificial anode protection effect. The absence of it 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 joint and decrease the corrosion resistance. The hydrogen content in the reducing atmosphere affects the zinc reduction efficiency and the quality of particle formation. Insufficient hydrogen may lead to an uneven or non-dense zinc layer, thus 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 of the material and the binding strength of particles. Excessive temperature may cause particle agglomeration or structural embrittlement, leading to an exacerbation of 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 binding 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 distribution of components. 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, seriously weakening the mechanical strength and corrosion resistance of the solder joints. In summary, the distribution and loading efficiency of zinc, the synergistic protection effect, the multi-scale interface design, the heat treatment system, and the control of the welding atmosphere are the key factors affecting the comprehensive performance of the composite solder of the present invention.

[0146] 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 all equivalent structural transformations made under the concept of the present invention using the content of the specification and drawings of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A solder for a highly corrosion-resistant multi-layer composite plate, characterized in that, It includes the following raw materials by weight parts: 6.0 - 12.0 parts of hollow silica microsphere-coated 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 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 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 described particle / SiC nanorod consists of SiC nanorods and particles loaded on the surface of the SiC nanorods.

2. The solder for highly corrosion-resistant multi-layer composite plates 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 a highly corrosion-resistant multi-layer composite plate according to claim 1, characterized in that, The described SiC nanorods and the mass ratio of the particles is 1:0.3 to 0.8; The average diameter of the SiC nanorods is 90 to 150 nm, and the average length is 0.5 to 2.0 μm. The particle has dimensions of 10 to 28 nm in all directions.

4. The solder for a highly corrosion-resistant multi-layer 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 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. Then, 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.

5. The solder for a 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, dissolve 15.0 - 20.0 parts of glucose in 200 - 300 parts of deionized water to form a transparent solution, transfer it to a polytetrafluoroethylene-lined autoclave with a filling rate of 35% - 45%, carry out hydrothermal reaction at 170 - 190 °C for 2.5 - 3.5 h, collect carbon microspheres by centrifugation at a centrifugal rate of 9000 - 11000 rpm, wash them alternately with deionized water and absolute ethanol 3 - 6 times and then dry at 75 - 85 °C for 5 - 7 h to obtain a carbon template. Disperse 1.0 - 1.5 parts of the carbon template in a mixed solvent composed of 200 - 250 parts of absolute ethanol and 90 - 110 parts of deionized water, form a suspension by stirring at 400 - 500 rpm and ultrasonic treatment for 25 - 35 min, add 1.8 - 2.2 parts of cetyltrimethylammonium bromide and then adjust the pH to 9.5 - 10.5, dropwise add 9 - 11 parts of tetraethyl orthosilicate and continuously stir at 400 - 500 rpm for 11 - 13 h to complete the hydrolysis and polycondensation reaction. After centrifuging to remove the supernatant, retain the precipitate. After 3 - 5 cycles of centrifugation at a centrifugal rate of 9000 - 11000 rpm / absolute ethanol washing / re-dispersion treatment process, dry at 75 - 85 °C for 11 - 13 h to obtain precursor B. Place 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 templating agent, and obtain porous hollow silica microspheres.

6. The solder for a highly corrosion-resistant multi-layer composite plate according to claim 1, characterized in that, The described 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 to stir 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 at 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.

7. The solder for highly corrosion-resistant multi-layer composite plates according to claim 1, wherein 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 absolute ethanol, and 10.0 - 20.0 parts of deionized water are mixed, and then 1.0 - 5.0 parts of 60 - 65wt% nitric acid is added. The hydrolysis reaction is carried out 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. Subsequently, 5.0 - 15.0 parts of glucose is added and 0.5 - 3.0 parts of nickel nitrate is introduced as a catalyst, and stirring continues for 1.0 - 3.0 h to form a homogeneous sol, which is then left standing for 12 - 36 h to complete the gelation process. The obtained wet gel is placed in a vacuum dryer at a vacuum degree of -0.05 - -0.08 MPa and a temperature of 60 - 80°C for 8 - 12 h to remove the solvent volatile matter and obtain a dry gel precursor D. The dry gel precursor D is placed in an argon atmosphere and heated at a heating rate of 5 - 10°C / min to 1200 - 1500°C, and then held at this temperature for 2.0 - 4.0 h to cause the carbon thermal reduction reaction between the silicon source and the carbon source to generate SiC nanorods.

8. The solder for a highly corrosion-resistant multi-layer composite plate according to claim 1, characterized in that, It is prepared through 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. After ultrasonic treatment for 20 - 40 min, a uniform suspension is formed. Add nanorods, 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 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 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 rosin glyceride, ethylene glycol, polyethylene glycol PEG - 400, and benzotriazole, and stir at a stirring rate of 300 - 500 rpm and a temperature of 40 - 60°C for 20 - 40 min. Carry out 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: Under the conditions of an extrusion temperature of 80 - 120°C and an extrusion pressure of 5 - 10 MPa, extrude the homogeneous slurry through a strip-shaped forming die with a pore diameter of 1.0 - 3.0 mm to obtain a strip-shaped blank; T5: Transfer the strip-shaped blank to a vacuum degassing chamber, degas it at a vacuum degree of -0.06 - -0.08 MPa and a temperature of 50 - 70°C for 10 - 20 min to remove internal bubbles and residual solvents. Send the degassed strip-shaped blank into a curing furnace, heat it at a heating rate of 5 - 8°C / min to 150 - 180°C under a nitrogen protection atmosphere, hold it at this temperature 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.

9. A welding process for a highly corrosion-resistant multi-layer composite plate, characterized in that, It includes the following steps: S1: The surface of the workpiece to be welded is successively subjected to mechanical grinding, alcohol wiping and ultrasonic cleaning to remove oil stains and oxide layers. 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. Select the groove form according to the base metal thickness. When the thickness ≤ 12 mm, use the I-shaped groove; when the thickness > 12 mm, use the 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 machining, confirm that the interface fitting rate ≥ 99% through ultrasonic testing; S2: Use Sn96.5Ag3.0Cu0.5 alloy welding wire for submerged arc welding of the base layer. 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. The transition layer uses nickel-based alloy welding wire for pulsed TIG welding. The welding current is 80 - 120 A, the arc length is 2 - 4 mm, the dilution rate < 15%, and the transition layer thickness is 1.5 - 2.0 mm. The cladding layer uses the solder described in any one of claims 1 - 8 for GTAW. The welding current is 100 - 150 A, the welding speed is 20 - 30 cm / min, and the thickness of the cladding layer weld covers the transition layer by 0.5 - 1.0 mm. Before cladding layer welding, apply polytetrafluoroethylene-based anti-spatter coating 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, use copper backing contact forced cooling, the cooling rate ≥ 50 °C / s, and the interlayer temperature is controlled such that the base layer ≤ 150 °C and the cladding layer ≤ 80 °C. 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 perform passivation treatment 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. The treated multi-layer composite plate is rinsed with deionized water and dried with nitrogen gas.

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