A stainless steel gap filling and low temperature connection process based on metal nano paste
By using a stainless steel gap filling and low-temperature bonding process based on metal nanoparticles, the stability and reliability issues of narrow gap bonding in stainless steel were solved, resulting in a high-strength and thermally conductive joint that avoids damage to the reactor core substrate.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NUCLEAR POWER INSTITUTE OF CHINA
- Filing Date
- 2026-03-11
- Publication Date
- 2026-06-16
AI Technical Summary
In the existing technology, stainless steel narrow gap connections lack suitable interface connection materials and matching gap filling technology, resulting in unstable and unreliable connections. Furthermore, existing connection methods may damage the core matrix or have poor thermal matching issues.
A stainless steel gap-filling and low-temperature bonding process based on metal nanoparticle slurry is adopted. The gap-filling process involves preparing a nano-metal slurry through ligand exchange of nano-metal particles and low-temperature sintering, including steps such as dispersion, cleaning, mixing, drying and low-temperature sintering of nano-metal particles.
It achieves stable and reliable stainless steel narrow gap connection, improves the mechanical and thermal properties of the connection joint, avoids damage to the core matrix, and achieves high strength and good thermal conductivity at low temperature.
Smart Images
Figure CN122210053A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of stainless steel gap filling and joining, and in particular to a stainless steel gap filling and low-temperature joining process based on metal nano-slurry. Background Technology
[0002] Traditional stainless steel gap connections in reactors include mechanical connections, welding, and bonding. Mechanical connections are divided into threaded connections and extrusion connections. Threaded connections use a threading machine to tighten the internal and external threads to achieve the connection. Extrusion connections involve radially extruding the inner tube into the sleeve to produce plastic deformation and achieve interference fit. However, machining can damage the reactor core matrix and leave safety hazards.
[0003] Welding utilizes high temperature or high pressure to join metals. While friction stir welding is more suitable for narrow seam welding, it is not suitable for narrow assembly gaps. Among existing technologies, narrow gap laser welding has become a new narrow seam welding technology due to its advantages such as high speed and large depth. However, it is suitable for welding plates with slightly larger gaps, which limits its application to pipes. It also has problems such as high requirements for the assembly accuracy of the welded parts, unsuitability for welding highly reflective and highly thermally conductive materials, low energy conversion efficiency, porosity or slag inclusions in the joints, and expensive equipment.
[0004] The bonding process involves injecting adhesive into the slits and forming a joint through curing and sintering. Adhesives are divided into two categories: organic and inorganic. Organic adhesives have a lower forming temperature but limited temperature resistance, making their joints unsuitable for high-temperature operation of the reactor core. Inorganic adhesives are mostly composed of inorganic salts, whose coefficients of thermal expansion differ significantly from those of the reactor core's metallic materials. This leads to potential failure risks such as interfacial thermal stress mismatch during service. Furthermore, their bonding structure is complex, resulting in high interfacial thermal resistance and low thermal conductivity, which may affect the reactor core's heat transfer performance.
[0005] Therefore, the existing connection methods may have certain bottlenecks when applied to narrow gap connections of stainless steel. There is an urgent need to find suitable interface connection materials and matching gap filling technologies to achieve stable and reliable narrow gap connections of stainless steel. Summary of the Invention
[0006] This invention provides a stainless steel gap filling and low-temperature bonding process based on metal nano-slurry, which solves the problem that the existing technology lacks suitable interface bonding materials and supporting gap filling technology for narrow gap bonding of stainless steel.
[0007] The technical solution of the present invention is as follows: This invention proposes a process for filling and low-temperature bonding of stainless steel gaps based on metal nanoparticle paste, the process comprising: Step 1: Ligand exchange of nano-metal particles; Step 1.1: Disperse the nano-metal particles with long-chain aliphatic amine ligands into n-hexane to obtain solution A; Step 1.2: Dissolve the exchange ligand in ethanol to obtain solution B; Step 1.3: Mix solution A and solution B, and centrifuge the mixture to obtain a precipitate; Step 1.4: Wash the precipitate with ethanol, dry the precipitate and grind it to obtain nano-metal particles; Step 2: Preparation of nano-metal slurry; Step 2.1: Prepare organic additives using dodecyl alcohol, ethyl cellulose, and terpineol; Step 2.2: Add the nano-metal particles obtained from grinding in Step 1 to the organic additives to obtain a nano-metal slurry; Step 3: Fill the gaps in the stainless steel sample with nano-metal slurry and sinter the stainless steel sample at low temperature.
[0008] In some embodiments, in step 1.1, 50 mL of n-hexane is added for every 1 g of long-chain fatty amine system nanoparticles.
[0009] In some embodiments, the amount of ethanol used in step 1.2 is 50 mL, and the amount of exchange ligand used is 20 mmol of ligand added per 1 g of nano-metal particles. The exchange ligand is ammonia, ethylenediamine, ammonium formate, formic acid, or isopropanolamine.
[0010] In some embodiments, the mixing of solution A and solution B in step 1.3 and centrifuging the mixture to obtain a precipitate specifically includes: mixing solution A and solution B, placing them in an ultrasonic cleaner and sonicating for 10-20 minutes (ultrasonic power of 80Hz), letting them stand for 5-10 minutes, centrifuging the mixture to obtain the product (centrifuge speed of 5000-20000rpm, centrifugation time of 10 minutes), and discarding the supernatant to collect the precipitate.
[0011] In some embodiments, step 1.4 involves washing the precipitate with ethanol, drying the precipitate, and grinding it to obtain nano-metal particles. Specifically, this includes: washing the precipitate with ethanol, using 50 mL of ethanol per 1 g of nano-metal particles; placing the precipitate and ethanol mixture in an ultrasonic cleaner and sonicating for 5-20 min (ultrasonic power of 80 Hz); centrifuging the precipitate and ethanol mixture to obtain the product, using a centrifuge at 5000-20000 rpm for 10 min; discarding the supernatant of the precipitate and ethanol mixture and collecting the precipitate; repeating the above washing process 3-5 times; drying the precipitate in a vacuum oven at 40-60 ℃ for 0.5-2 h; and grinding the precipitate in a mortar and pestle to obtain nano-metal particles after drying.
[0012] In some embodiments, the preparation of the organic additive using dodecyl alcohol, ethyl cellulose, and terpineol in step 2.1 specifically includes: adding dodecyl alcohol and ethyl cellulose to terpineol to obtain a mixture, wherein the terpineol content is 85-95 wt%, the dodecyl alcohol content is 3.5-13.5 wt%, and the ethyl cellulose content is 1.5-7.5 wt%. The mixture is continuously stirred with magnetic stirring at a speed of 1000 rpm for 3-6 hours. After the ethyl cellulose is completely dissolved, the mixture is ultrasonically cleaned to remove air bubbles. The ultrasonic power of the ultrasonic machine is 80 Hz, and the ultrasonic time is 5-20 minutes, to obtain the final organic additive.
[0013] In some embodiments, step 2.2 specifically includes: adding the nano-metal particles manufactured in step one to an organic additive to obtain a slurry, wherein the content of the nano-metal particles is 50-90wt% and the content of the organic additive is 10-50wt%, and the slurry is stirred into a paste using a vacuum degassing mixer to obtain a nano-metal slurry.
[0014] In some embodiments, step three specifically includes: Step 3.1: Insert the injection needle into the gap of the stainless steel sample, use casting adhesive to seal the bottom of the stainless steel sample and fix the needle, and let it stand for 24 hours after sealing.
[0015] Step 3.2: After the casting adhesive has completely cured, inject the nano-metal slurry prepared in Step 2 into the gaps of the stainless steel sample from bottom to top until the nano-metal slurry overflows from the top; place the stainless steel sample in a vacuum drying oven at 40-60 ℃ and dry it for 0.5-2 h, then inject again; repeat the above injection and drying operation 3-5 times to complete the filling of the stainless steel sample; the nano-metal slurry injection is carried out using a high-pressure constant flow pump, with a flow rate range of 0.01-50 mL / min, flow accuracy <0.5%, and pressure range of 0-25 MPa; Step 3.3: Place the filled stainless steel sample into a muffle furnace for sintering. The heating rate of the muffle furnace is 5-10 ℃ / min, the holding temperature is 250-600℃, and the holding time is 0.5-5h. Finally, the stainless steel sample is cooled to room temperature with the furnace.
[0016] In some embodiments, when ammonia is used as the exchange ligand in the process, the process can prepare a dual-ligand nano-metal slurry. For the dual-ligand nano-metal slurry, step two is as follows: Step 2.1: Add dodecyl alcohol and ethyl cellulose to terpineol to obtain a mixture with terpineol content of 90 wt%, dodecyl alcohol content of 7.5 wt%, and ethyl cellulose content of 2.5 wt%. Stir the mixture with magnetic stirring for 6 hours at a speed of 1000 rpm until the ethyl cellulose is completely dissolved. Then, use an ultrasonic machine to remove air bubbles from the mixture at an ultrasonic power of 80 Hz for 20 minutes to obtain the organic additive. Step 2.2: Mix the nano-metal particles obtained in Step 1 and the long-chain fatty amine nano-metal particles as ligands at a mass ratio of 1:1. Add the mixed nano-metal particles to the organic additives, wherein the content of the mixed nano-metal particles is 70wt% and the content of the organic additives is 30wt%. Use a vacuum degassing mixer to stir the mixed slurry into a paste to obtain a dual-ligand nano-metal slurry.
[0017] In some embodiments, when ammonia is used as the exchange ligand in the process, the process can prepare a dual-ligand nano-metal slurry. For the dual-ligand nano-metal slurry, step three is as follows: Step 3.1: Insert the injection needle into the gap of the stainless steel sample, use casting adhesive to seal the bottom of the stainless steel sample and fix the needle at the same time, and let it stand for 24 hours after sealing.
[0018] Step 3.2: After the casting adhesive has completely cured, inject the dual-ligand nano-metal slurry into the gaps of the stainless steel sample from bottom to top until the dual-ligand nano-metal slurry overflows from the top; place the stainless steel sample in a 60 ℃ vacuum drying oven to dry for 0.5 h, and inject again; repeat the above injection and drying operation 3-5 times to complete the filling of the stainless steel sample; the injection of the dual-ligand nano-metal slurry is carried out by a micro high-pressure constant flow pump, the flow rate range of which is 30 mL / min, the flow accuracy is <0.5%, and the pressure range is 25 MPa.
[0019] Step 3.3: Place the filled stainless steel sample into a muffle furnace for sintering. The heating rate is 5℃ / min, the holding temperature is 600℃, and the holding time is 1 h. The stainless steel sample is then cooled to room temperature with the furnace.
[0020] The implementation of this invention has the following beneficial effects: This invention proposes a stainless steel gap-filling and low-temperature bonding process based on metal nanoparticle slurry. The nanoparticles used in this invention possess excellent processability, gap-filling operability, and compatibility with the stainless steel matrix. Furthermore, the nanoparticles can achieve low-temperature sintering and high-temperature applications, achieving stable and reliable narrow-gap bonding of stainless steel. Simultaneously, through ligand exchange of the nanoparticles, they can be sintered at low temperatures in an air atmosphere to obtain stainless steel joints with high interfacial strength and good thermal conductivity. The use of a potting method results in a denser gap filling, improving the mechanical and thermal properties of the stainless steel joints. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of ligand exchange of nano-metal particles in a stainless steel gap-filling and low-temperature bonding process based on metal nano-slurry, as proposed in an embodiment of the present invention. Figure 2 This invention provides a cross-sectional microstructure of a stainless steel sample filled with a single-ligand nano-metal paste, which is part of a stainless steel gap-filling and low-temperature bonding process based on metal nano-slurry. Figure 3 This is a cross-sectional microstructure of a stainless steel sample filled with a dual-ligand nano-metal paste, which is part of a stainless steel gap-filling and low-temperature bonding process based on metal nano-slurry proposed in an embodiment of the present invention. Figure 4 The thermal properties of a stainless steel sample filled with a single-ligand nano-metal paste are shown in the embodiment of the present invention, which is a stainless steel gap-filling and low-temperature bonding process based on metal nano-slurry. Detailed Implementation
[0022] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0023] like Figures 1 to 4 As shown, this invention proposes a stainless steel gap-filling and low-temperature bonding process based on metal nanoparticle paste, the process comprising: Step 1: Ligand exchange of nano-metal particles; Step 1.1: Disperse the nano-metal particles with a long-chain aliphatic amine ligand into n-hexane. The amount of n-hexane added is 50 mL for every 1 g of nano-metal particles. This solution is defined as solution A.
[0024] Step 1.2: Dissolve the exchange ligand in 50 mL of ethanol. The amount of exchange ligand used is 20 mmol of ligand per 1 g of nano-metal particles. This solution is defined as solution B. The exchange ligand can be ammonia, ethylenediamine, ammonium formate, formic acid, or isopropanolamine. In this example, ammonia is used as an example.
[0025] Step 1.3: Mix solution A and solution B, place them in an ultrasonic cleaner and sonicate for 20 minutes at an ultrasonic power of 80 Hz, then let stand for 10 minutes, and then centrifuge to separate the product at a speed of 10,000 rpm for 10 minutes. Discard the supernatant and take the precipitate.
[0026] Step 1.4: The precipitate was washed with ethanol. The amount of ethanol was 50 mL per 1 g of nano-metal particles. The mixture of precipitate and ethanol was placed in an ultrasonic cleaner and ultrasonicated for 20 min at 80 Hz. The product was then separated by centrifugation at 10000 rpm for 10 min. The supernatant was discarded and the precipitate was collected. The mixture was washed three times. The precipitate was then placed in a vacuum oven and dried at 60 ℃ for 30 min. After drying, the nano-metal particles with ammonia as the ligand were ground in a mortar and pestle.
[0027] Step 2: Preparation of nano-metal pastes, including single-ligand nano-metal pastes and dual-ligand nano-metal pastes. The preparation method of single-ligand nano-metal pastes is illustrated in the following example: Step 2.1: Add dodecyl alcohol and ethyl cellulose to terpineol, wherein the content of terpineol is 85 wt%, the content of dodecyl alcohol is 13.5 wt%, and the content of ethyl cellulose is 1.5 wt%. Stir continuously with magnetic stirring for 4 hours at a speed of 1000 rpm to completely dissolve the ethyl cellulose. Finally, remove air bubbles by ultrasonication with an ultrasonic power of 80 Hz for 20 minutes to obtain the final organic additive.
[0028] Step 2.2: Add the nano-metal particles obtained in Step 1 to the organic additives, wherein the content of nano-metal particles is 60wt% and the content of organic additives is 40wt%. Use a vacuum degassing mixer to stir the slurry into a paste, and finally obtain the nano-metal slurry.
[0029] The following is an example of a method for preparing dual-ligand nano-metal paste: Step 2.1: Add dodecyl alcohol and ethyl cellulose to terpineol, wherein the content of terpineol is 90 wt%, the content of dodecyl alcohol is 7.5 wt%, and the content of ethyl cellulose is 2.5 wt%. The wt% is a weight percentage. Stir continuously with magnetic stirring for 6 hours at a speed of 1000 rpm to completely dissolve the ethyl cellulose. Finally, remove the air bubbles by ultrasonication at a power of 80 Hz for 20 minutes to obtain the final organic additive.
[0030] Step 2.2: Mix the nano-metal particles obtained in Step 1 and the long-chain fatty amine nano-metal particles as ligands at a mass ratio of 1:1. Add the mixed nano-metal particles to the organic additives. The content of the mixed nano-metal particles is 70wt% and the content of the organic additives is 30wt%. Use a vacuum degassing mixer to stir the slurry into a paste to finally obtain the dual-ligand nano-metal slurry.
[0031] Step 3: Fill the gaps in the stainless steel with nano-metal slurry and perform low-temperature sintering, such as... Figure 2 As shown, the specific examples of the interstitial filling and low-temperature sintering method for single-ligand nano-metal slurry are as follows: Step 3.1: Insert the injection needle into the gap of the stainless steel, use casting adhesive to seal the bottom of the stainless steel sample and fix the needle at the same time, and let it stand for 24 hours after sealing.
[0032] Step 3.2: After the casting adhesive has completely cured, the prepared single-ligand nano-metal slurry, modified with ammonia as the ligand, is injected into the gap from bottom to top until it overflows from the top. The stainless steel sample is then dried in a 60 ℃ vacuum drying oven for 0.5 h, followed by re-injection. This process is repeated 5 times to obtain a fully filled stainless steel sample. The injection of the single-ligand nano-metal slurry is performed using a micro high-pressure constant flow pump with a flow rate range of 40 mL / min, a flow accuracy of <0.5%, and a pressure range of 25 MPa.
[0033] Step 3.3: Place the filled stainless steel sample into a muffle furnace for sintering. The heating rate is 5℃ / min, the holding temperature is 400℃, the holding time is 3h, and finally the sample is cooled to room temperature in the furnace.
[0034] like Figure 3 As shown, the specific examples of the interstitial filling and low-temperature sintering method for dual-ligand nano-metal slurry are as follows: Step 3.1: Insert the injection needle into the gap of the stainless steel, use casting adhesive to seal the bottom of the stainless steel sample and fix the needle at the same time, and let it stand for 24 hours after sealing.
[0035] Step 3.2: After the casting adhesive has completely cured, the prepared dual-ligand nano-metal slurry is injected into the gap from bottom to top until the slurry overflows from the top; the stainless steel sample is dried in a 60 ℃ vacuum drying oven for 0.5 h, and then injected again; this process is repeated 5 times to obtain a fully filled stainless steel sample. The injection of the dual-ligand nano-metal slurry is carried out using a micro high-pressure constant flow pump with a flow rate range of 30 mL / min, a flow accuracy of <0.5%, and a pressure range of 25 MPa.
[0036] Step 3.3: Place the filled stainless steel sample into a muffle furnace for sintering. The heating rate is 5℃ / min, the holding temperature is 600℃, the holding time is 1 h, and finally the sample is cooled to room temperature in the furnace.
[0037] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.
Claims
1. A stainless steel gap-filling and low-temperature bonding process based on metal nanoparticle paste, characterized in that, The process includes: Step 1: Ligand exchange of nano-metal particles; Step 1.1: Disperse the nano-metal particles with long-chain aliphatic amine ligands into n-hexane to obtain solution A; Step 1.2: Dissolve the exchange ligand in ethanol to obtain solution B; Step 1.3: Mix solution A and solution B, and centrifuge the mixture to obtain a precipitate; Step 1.4: Wash the precipitate with ethanol, dry the precipitate and grind it to obtain nano-metal particles; Step 2: Preparation of nano-metal slurry; Step 2.1: Prepare organic additives using dodecyl alcohol, ethyl cellulose, and terpineol; Step 2.2: Add the nano-metal particles obtained from grinding in Step 1 to the organic additive to obtain a nano-metal slurry; Step 3: Fill the gaps in the stainless steel sample with the nano-metal slurry and then sinter the stainless steel sample at low temperature.
2. The stainless steel gap-filling and low-temperature bonding process based on metal nanoparticle paste according to claim 1, characterized in that, In step 1.1, 50 mL of n-hexane is added for every 1 g of the nano-metal particles of the long-chain fatty amine system.
3. The stainless steel gap-filling and low-temperature bonding process based on metal nanoparticle paste according to claim 2, characterized in that, In step 1.2, the amount of ethanol used is 50 mL, and the amount of exchange ligand used is 20 mmol of ligand added per 1 g of nano-metal particles. The exchange ligand is ammonia, ethylenediamine, ammonium formate, formic acid, or isopropanolamine.
4. The stainless steel gap-filling and low-temperature bonding process based on metal nanoparticle paste according to claim 3, characterized in that, Step 1.3, which involves mixing solution A and solution B and centrifuging the mixture to obtain a precipitate, specifically includes: mixing solution A and solution B, placing them in an ultrasonic cleaner and sonicating for 10-20 minutes (the ultrasonic cleaner has an ultrasonic power of 80 Hz), letting them stand for 5-10 minutes, centrifuging the mixture to obtain the product (the centrifuge speed is 5000-20000 rpm and the centrifugation time is 10 minutes), and discarding the supernatant to collect the precipitate.
5. The stainless steel gap-filling and low-temperature bonding process based on metal nano-slurry according to claim 4, characterized in that, In step 1.4, the precipitate is washed with ethanol, dried, and ground to obtain nano-metal particles. Specifically, this includes: washing the precipitate with ethanol, using 50 mL of ethanol per 1 g of nano-metal particles; placing the precipitate and ethanol mixture in an ultrasonic cleaner and sonicating for 5-20 min (the ultrasonic cleaner has an ultrasonic power of 80 Hz); centrifuging the precipitate and ethanol mixture to obtain the product, using a centrifuge at a speed of 5000-20000 rpm for 10 min; discarding the supernatant of the precipitate and ethanol mixture and collecting the precipitate; repeating the above washing process 3-5 times; placing the precipitate in a vacuum oven and drying it at 40-60 ℃ for 0.5-2 h; and grinding the precipitate in a mortar and pestle to obtain nano-metal particles after drying.
6. The stainless steel gap-filling and low-temperature bonding process based on metal nanoparticle paste according to claim 5, characterized in that, The preparation of the organic additive using dodecyl alcohol, ethyl cellulose, and terpineol in step 2.1 specifically includes: adding dodecyl alcohol and ethyl cellulose to terpineol to obtain a mixture, wherein the terpineol content is 85-95 wt%, the dodecyl alcohol content is 3.5-13.5 wt%, and the ethyl cellulose content is 1.5-7.5 wt%. The mixture is continuously stirred magnetically for 3-6 hours at a speed of 1000 rpm. After the ethyl cellulose is completely dissolved, the mixture is ultrasonically cleaned to remove air bubbles. The ultrasonic power is 80 Hz, and the ultrasonic time is 5-20 minutes, to obtain the final organic additive.
7. The stainless steel gap-filling and low-temperature bonding process based on metal nanoparticle paste according to claim 6, characterized in that, Step 2.2 specifically includes: adding the nano-metal particles manufactured in step one to the organic additive to obtain a slurry, wherein the content of the nano-metal particles is 50-90wt% and the content of the organic additive is 10-50wt%, and the slurry is stirred into a paste using a vacuum degassing mixer to obtain the nano-metal slurry.
8. The stainless steel gap-filling and low-temperature bonding process based on metal nanoparticle paste according to claim 7, characterized in that, Step three specifically includes: Step 3.1: Insert the injection needle into the gap of the stainless steel sample, use casting adhesive to seal the bottom of the stainless steel sample and fix the needle, and let it stand for 24 hours after sealing; Step 3.2: After the casting adhesive has completely cured, inject the nano-metal slurry prepared in Step 2 into the gaps of the stainless steel sample from bottom to top until the nano-metal slurry overflows from the top; place the stainless steel sample in a vacuum drying oven at 40-60 ℃ and dry it for 0.5-2 h, then inject again; repeat the above injection and drying operation 3-5 times to complete the filling of the stainless steel sample; the nano-metal slurry injection is performed using a high-pressure constant flow pump, the flow rate range of the high-pressure constant flow pump is 0.01-50 mL / min, the flow accuracy is <0.5%, and the pressure range is 0-25 MPa; Step 3.3: Place the filled stainless steel sample into a muffle furnace for sintering. The heating rate of the muffle furnace is 5-10℃ / min, the holding temperature is 250-600℃, and the holding time is 0.5-5h. Finally, the stainless steel sample is cooled to room temperature with the furnace.
9. The stainless steel gap-filling and low-temperature bonding process based on metal nanoparticle paste according to claim 5, characterized in that, When ammonia is used as the exchange ligand in the process, the process can prepare a dual-ligand nano-metal slurry. For the dual-ligand nano-metal slurry, step two is as follows: Step 2.1: Add dodecyl alcohol and ethyl cellulose to terpineol to obtain a mixture, wherein the terpineol content is 90 wt%, the dodecyl alcohol content is 7.5 wt%, and the ethyl cellulose content is 2.5 wt%. The mixture is continuously stirred magnetically for 6 hours at a speed of 1000 rpm. After the ethyl cellulose is completely dissolved, the mixture is ultrasonically removed by ultrasonication at a power of 80 Hz for 20 minutes to obtain an organic additive. Step 2.2: Mix the nano-metal particles obtained in Step 1 and the long-chain fatty amine nano-metal particles as ligands at a mass ratio of 1:
1. Add the mixed nano-metal particles to the organic additives, wherein the content of the mixed nano-metal particles is 70wt% and the content of the organic additives is 30wt%. Use a vacuum degassing mixer to stir the mixed slurry into a paste to obtain a dual-ligand nano-metal slurry.
10. The stainless steel gap-filling and low-temperature bonding process based on metal nanoparticle paste according to claim 9, characterized in that, When ammonia is used as the exchange ligand in the process, the process can prepare a dual-ligand nano-metal slurry. For the dual-ligand nano-metal slurry, step three is as follows: Step 3.1: Insert the injection needle into the gap of the stainless steel sample, use casting adhesive to seal the bottom of the stainless steel sample and fix the needle at the same time, and let it stand for 24 hours after sealing; Step 3.2: After the casting adhesive has completely cured, inject the dual-ligand nano-metal slurry into the gaps of the stainless steel sample from bottom to top until the slurry overflows from the top; place the stainless steel sample in a 60 ℃ vacuum drying oven to dry for 0.5 h, and inject again; repeat the above injection and drying operation 3-5 times to complete the filling of the stainless steel sample; the injection of the dual-ligand nano-metal slurry is carried out by a micro high-pressure constant flow pump, the flow rate range of which is 30 mL / min, the flow accuracy is <0.5%, and the pressure range is 25 MPa; Step 3.3: Place the filled stainless steel sample into a muffle furnace for sintering. The heating rate is 5℃ / min, the holding temperature is 600℃, and the holding time is 1 h. The stainless steel sample is then cooled to room temperature with the furnace.