Nickel core ceramic composite powder, slurry and preparation method thereof, and multilayer ceramic capacitor

Abstract

This invention provides a nickel-core ceramic composite powder, a slurry, a preparation method thereof, and a multilayer ceramic capacitor; wherein the nickel-core ceramic composite powder comprises core-shell particles, the core-shell particles comprising a nickel core and a ceramic layer covering the nickel core, wherein the nickel core and the ceramic layer are bonded together by a coupling agent; the slurry is obtained by mixing the nickel-core ceramic composite powder, a slurry solvent, and a binder; the internal electrode in the multilayer ceramic capacitor can be made from the nickel-core ceramic composite powder or a slurry containing the nickel-core ceramic composite powder.

Description

Technical Field

[0001] This invention relates to the field of multilayer ceramic capacitors, specifically to a nickel-core ceramic composite powder, slurry, preparation method thereof, and multilayer ceramic capacitor. Background Technology

[0002] Multilayer ceramic capacitors (MLCCs) are monolithic capacitors composed of stacked alternating metal electrodes and ceramic dielectric layers. They are continuously evolving towards higher capacitance, lower cost, smaller size, and higher reliability, and are widely used in various industries such as laptops, smartphones, digital home appliances, automotive electronics, and automatic control instruments. In recent years, with the development of automotive electronics and electric vehicles, the demand for automotive-grade MLCCs has surged. Automotive MLCCs cover a wide range of models, with stringent temperature and environmental requirements, placing higher demands on their lifespan and reliability. Base metal electrode products using nickel have advantages over precious metal products, such as lower resistivity and lower cost. However, with the increasing demands for high capacitance and high reliability in MLCCs, the dielectric and nickel electrode layers are becoming increasingly thinner, requiring the inner electrode to be well-matched to the shrinkage of the dielectric during sintering. During sintering, the nickel electrode may exhibit a significant temperature difference with the dielectric material, making it prone to defects such as cracks and delamination. To control shrinkage and achieve co-firing with the dielectric layer, nickel internal electrodes typically incorporate nano-barium carbonate into the slurry and are thoroughly mixed and dispersed. Traditionally, the shrinkage initiation temperature of the nickel electrode during sintering is controlled by adjusting the particle size and amount of nano-barium titanate. The typical initiation temperature for nickel sintering is 400℃. The driving force for sintering is the formation of sintering necks through contact between nickel powder particles. However, due to slurry viscosity issues, the traditional method of adding barium titanate cannot achieve uniform dispersion in the slurry system, and the particles are prone to secondary agglomeration. After printing and drying, the barium titanate particles cannot form an effective insulating layer between the nickel powder particles, thus only delaying the shrinkage process to a certain extent and not completely eliminating the sintering phenomenon between nickel powder particles after 400℃. When controlling nickel shrinkage solely by adjusting the amount of barium titanate added, the extra barium titanate will gradually diffuse into the dielectric layer during sintering, disrupting the core-shell structure of the barium titanate grains in the dielectric layer and severely affecting the reliability of MLCCs. Excessive barium titanate that fails to be discharged from the electrode layer in time will severely affect the continuity of the electrode layer, thereby reducing the effective facing area of ​​the MLCC product and lowering its capacity. Insufficient barium titanate addition will not effectively delay the shrinkage of the nickel electrode, leading to electrode spheroidization and causing short-circuit defects in the MLCC product.

[0003] Therefore, how to improve the performance of multilayer ceramic capacitors has become an urgent problem to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a nickel-core ceramic composite powder, slurry, and preparation method thereof, as well as a multilayer ceramic capacitor, to obtain a multilayer ceramic capacitor with better performance.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A nickel-core ceramic composite powder, the composite powder comprising core-shell particles, the core-shell particles comprising a nickel core and a ceramic layer covering the nickel core, wherein the nickel core and the ceramic layer are bonded together via a coupling agent.

[0007] In some embodiments of the present invention, the coupling agent has the molecular formula (YR). n SiX 4-n Where n is 1 or 2, YR is a non-hydrolyzable organic group, and X is a hydrolyzable group;

[0008] Preferably, Y is vinyl, amino, epoxy, propylene oxide, or methacryloyloxy, R is a linking group, preferably a direct bond or a C1-C4 alkylene group, such as methylene, -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, and X is a C1-C4 alkoxy group, more preferably ethoxy or methoxy.

[0009] In some embodiments of the present invention, in the core-shell particles, the silicon atoms in the coupling agent are connected to the oxygen atoms on the surface of the nickel core via hydrogen bonds or condensed with the hydroxyl or oxygen atoms on the surface of the nickel core.

[0010] And / or, the silicon atoms in the coupling agent are connected to the oxygen atoms on the surface of the ceramic layer via hydrogen bonds through hydroxyl groups or undergo condensation with the hydroxyl or oxygen groups on the surface of the ceramic layer.

[0011] In some embodiments of the present invention, the tap density of the composite powder is 2-5 g / cm³. 3 Preferably, it is 2.5–4.5 g / cm³. 3 ;

[0012] And / or, the particle size of the composite powder is 170-400 nm, preferably 180-380 nm.

[0013] In some embodiments of the present invention, the nickel core has a particle size of 150–300 nm and the ceramic layer has a thickness of 10–100 nm, preferably 20–100 nm.

[0014] To achieve the above objectives, the present invention also provides the following technical solutions:

[0015] A method for preparing the above-mentioned nickel-core ceramic composite powder, the method comprising the following steps:

[0016] S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic suspension is obtained by mixing and dispersing ceramic powder, coupling agent, preferably silane coupling agent, organic solvent and alkaline regulator, and the modified nickel powder is obtained by treating with alkaline solution, washing with organic solvent and drying.

[0017] S2, the ceramic suspension is mixed and dispersed with the modified nickel powder to obtain a suspension of nickel powder coated with ceramic.

[0018] S3, freeze-dry the suspension obtained in step S2 to obtain the composite powder.

[0019] In some embodiments of the present invention, step S3 further includes adding the adhesive to the suspension obtained in step S2 and then dispersing it to obtain the composite powder slurry.

[0020] Some embodiments of the present invention include at least one of the following features:

[0021] Preferably, in step S1, the organic solvent is at least one selected from n-propanol, isopropanol, and n-butanol;

[0022] Preferably, in step S1, the amount of ceramic powder added to the ceramic suspension is 40-55 wt.%, the amount of coupling agent, preferably silane coupling agent, added is 0.5-5 wt.%, the amount of organic solvent added is 41-56 wt.%, and the amount of alkalinity regulator added is 1-4 wt.%.

[0023] Preferably, in step S1, the molecular formula of the silane coupling agent is (YR). n SiX 4-n Where n is 1 or 2, YR is a non-hydrolyzable organic group, X is a hydrolyzable group, more preferably, Y is vinyl, amino, epoxy, epoxypropoxy or methacryloyloxy, R is a linking group, preferably a direct bond or C1-C4 alkylene group, such as methylene, -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, X is a C1-C4 alkoxy group, more preferably ethoxy or methoxy, and most preferably, the silane coupling agent is at least one selected from γ-aminopropyltriethoxysilane, vinyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane;

[0024] Preferably, in step S1, the ceramic powder is at least one of barium titanate, calcium zirconate, strontium zirconate, and zirconium oxide;

[0025] Preferably, in step S1, the particle size of the ceramic powder is 20-100 nm, more preferably 30-90 nm;

[0026] Preferably, in step S1, the dispersion treatment is carried out by sand milling; more preferably, the sand milling is carried out by zirconium balls with a diameter of 0.02 to 0.1 mm, the linear velocity of the sand milling is 10 to 14 m / s, and the sand milling time is 2 to 4 h.

[0027] Preferably, in step S1, the alkalinity regulator is at least one selected from di(2-ethylhexyl)amine, hexamethylenediamine, 1,4-butanediamine, and 2-ethylhexylamine;

[0028] Preferably, in step S1, the nickel powder is obtained by physical vapor deposition or chemical vapor deposition. More preferably, the particle size of the nickel powder is 150-300 nm.

[0029] Some embodiments of the present invention include at least one of the following features:

[0030] Preferably, in step S1, the alkaline solution is an aqueous solution of potassium hydroxide; more preferably, the pH value of the aqueous solution of potassium hydroxide is 9 to 12.

[0031] Preferably, in step S1, the treatment with alkaline solution includes mixing with the alkaline solution, heating and stirring, and filtering;

[0032] Preferably, in the heating and stirring process, the heating temperature is 70–100°C and the stirring time is 7–12 hours.

[0033] Preferably, in step S1, each organic solvent is independently selected from at least one of n-propanol, isopropanol, and n-butanol.

[0034] In some embodiments of the present invention, in step S2, the mass ratio of the ceramic powder to the modified nickel powder is (6-10):100;

[0035] And / or, in step S2, the dispersion treatment is carried out by sand milling, using zirconium balls with a diameter of 0.1 to 0.3 mm, the linear speed of the sand milling is 8 to 10 m / s, and the sand milling time is 2 to 4 hours.

[0036] Some embodiments of the present invention include at least one of the following features:

[0037] Preferably, in step S3, the suspension before the addition of the adhesive is subjected to solvent replacement using a negative pressure biaxial mixer at 70-90°C; more preferably, the negative pressure of the negative pressure biaxial mixer is -0.1 to -0.01 MPa.

[0038] Preferably, in step S3, a three-roll mill is used for dispersion to obtain the slurry. More preferably, the pressure of the three-roll mill is 15-30 bar, the dispersion temperature is 20-30°C, and the dispersion is performed 3-5 times.

[0039] In some embodiments of the present invention, in step S4, a freeze dryer is used for freeze drying, and the cold trap temperature is -70 to -50°C, preferably -65 to -55°C.

[0040] To achieve the above objectives, the present invention also provides the following technical solutions:

[0041] A slurry, the raw materials of which include:

[0042] Slurry solvent;

[0043] Adhesives;

[0044] Nickel-core ceramic composite powder, the composite powder comprising core-shell particles, the core-shell particles comprising a nickel core and a ceramic layer covering the nickel core, wherein the nickel core and the ceramic layer are bonded together via a coupling agent.

[0045] In some embodiments of the present invention, the coupling agent contains at least silicon, oxygen and hydrogen.

[0046] In some embodiments of the present invention, the coupling agent has the molecular formula (YR). n SiX 4-n Where n is 1 or 2, YR is a non-hydrolyzable organic group, and X is a hydrolyzable group;

[0047] Preferably, Y is a vinyl, amino, or methacryloyloxy group, R is a linking group, preferably a direct bond or a C1-C4 alkylene group, such as methylene, -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, and X is a C1-C4 alkoxy group, preferably ethoxy or methoxy.

[0048] In some embodiments of the present invention, the silicon atoms in the coupling agent are connected to the oxygen atoms on the surface of the nickel core via hydrogen bonds through hydroxyl groups or undergo condensation with the hydroxyl or oxygen groups on the surface of the nickel core;

[0049] And / or, the silicon atoms in the coupling agent are connected to the oxygen atoms on the surface of the ceramic layer via hydrogen bonds through hydroxyl groups or undergo condensation with the hydroxyl or oxygen groups on the surface of the ceramic layer.

[0050] Some embodiments of the present invention include at least one of the following features:

[0051] The slurry solvent is at least one of dihydroterpineol acetate, isoborneol acetate, isoamyl acetate, and sec-butyl acetate.

[0052] And / or, the adhesive is at least one of ethyl cellulose resin, polyvinyl butyral resin, and acrylic resin;

[0053] And / or, in the raw materials of the slurry, the content of the slurry solvent is 30-40 wt.%, the content of the binder is 3-6 wt.%, and the content of the composite powder is 55-60 wt.

[0054] To achieve the above objectives, the present invention also provides the following technical solutions:

[0055] A method for preparing the above-mentioned slurry, the method comprising the following steps:

[0056] S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic suspension is obtained by mixing and dispersing ceramic powder, coupling agent, preferably silane coupling agent, organic solvent and alkaline regulator, and the modified nickel powder is obtained by treating the nickel powder with an alkaline solution, washing it with an organic solvent and drying it.

[0057] S2, the ceramic suspension is mixed and dispersed with the modified nickel powder to obtain a suspension of nickel powder coated with ceramic.

[0058] S3, the suspension obtained in step S2 is solvent-displaced using a slurry solvent. After the displacement is complete, a binder is added to obtain the slurry.

[0059] Some embodiments of the present invention include at least one of the following features:

[0060] Preferably, in step S1, each organic solvent is independently selected from at least one of n-propanol, isopropanol, and n-butanol;

[0061] Preferably, in step S1, the molecular formula of the silane coupling agent is (YR). n SiX 4-n Where n is 1 or 2, YR is a non-hydrolyzable organic group, X is a hydrolyzable group, more preferably, Y is vinyl, amino, epoxy, epoxypropoxy or methacryloyloxy, R is a linking group, preferably a direct bond or C1-C4 alkylene group, such as methylene, -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, X is a C1-C4 alkoxy group, more preferably ethoxy or methoxy, and most preferably, the silane coupling agent is at least one selected from γ-aminopropyltriethoxysilane, vinyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane;

[0062] Preferably, in step S1, the amount of ceramic powder added to the ceramic suspension is 40-55 wt.%, the amount of silane coupling agent added is 0.5-5 wt.%, the amount of organic solvent added is 41-56 wt.%, and the amount of alkaline regulator added is 1-4 wt.%.

[0063] Preferably, in step S1, the ceramic powder is at least one of barium titanate, calcium zirconate, strontium zirconate, and zirconium oxide.

[0064] Preferably, in step S1, the particle size of the ceramic powder is 20-100 nm, more preferably 30-90 nm;

[0065] Preferably, in step S1, the dispersion treatment is carried out by sand milling; more preferably, the sand milling is carried out by zirconium balls with a diameter of 0.02 to 0.1 mm, the linear velocity of the sand milling is 10 to 14 m / s, and the sand milling time is 2 to 4 h.

[0066] Preferably, the alkalinity regulator is at least one of di(2-ethylhexyl)amine, hexamethylenediamine, 1,4-butanediamine, and 2-ethylhexylamine.

[0067] Some embodiments of the present invention include at least one of the following features:

[0068] In step S1, the alkaline solution is an aqueous solution of potassium hydroxide, preferably with a pH value of 9 to 12.

[0069] And / or, in step S1, the treatment with alkaline solution includes mixing with the alkaline solution, heating and stirring, and filtering; preferably, in the heating and stirring, the heating temperature is 70-100°C, and the stirring time is 7-12 hours.

[0070] And / or, in step S1, the organic solvent is at least one of n-propanol, isopropanol, and n-butanol.

[0071] In some embodiments of the present invention, in step S2, the mass ratio of the ceramic powder to the modified nickel powder is (6-10):100;

[0072] And / or, in step S2, the dispersion treatment is carried out by sand milling, using zirconium balls with a diameter of 0.1 to 0.3 mm, the linear speed of the sand milling is 8 to 10 m / s, and the sand milling time is 2 to 4 hours.

[0073] Some embodiments of the present invention include at least one of the following features:

[0074] In step S3, after the solvent replacement is completed, the binder is added and dispersed to obtain the slurry;

[0075] And / or, in step S3, a negative pressure twin-shaft mixer is used to perform the solvent replacement at 70-90°C. Preferably, the negative pressure of the negative pressure twin-shaft mixer is -0.1 to -0.01 MPa.

[0076] And / or, in step S3, the adhesive is at least one of ethyl cellulose resin, phenolic resin, acrylic resin, and polyvinyl butyral resin;

[0077] And / or, in step S3, a three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 15-30 bar, the dispersion temperature is 20-30°C, and the dispersion is performed 3-5 times.

[0078] To achieve the above objectives, the present invention also provides the following technical solutions:

[0079] A method for preparing a slurry, the method comprising the following steps:

[0080] S1, providing the above-mentioned composite powder, or providing the nickel core ceramic composite powder obtained by the above method;

[0081] S2, the composite powder, slurry solvent, and binder are mixed and dispersed to obtain a slurry.

[0082] To achieve the above objectives, the present invention also provides the following technical solutions:

[0083] A multilayer ceramic capacitor includes an inner electrode, a dielectric layer, and an outer electrode. The inner electrode is disposed on the dielectric layer, and the two ends of the inner electrode are connected to the outer electrode through a spacer.

[0084] The inner electrode is prepared using the nickel core ceramic composite powder described above, or the inner electrode is prepared using the nickel core ceramic composite powder obtained by the method described above, or the inner electrode is prepared using the slurry described above, or the inner electrode is prepared using the slurry obtained by the method described above, or the inner electrode is prepared using the slurry described above.

[0085] Other applicable areas will become apparent from the description provided in this disclosure.

[0086] The descriptions and specific examples in the invention summary are intended to be illustrative only and are not intended to limit the scope of this disclosure.

[0087] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0088] This invention provides a nickel-core ceramic composite powder, a slurry, a preparation method thereof, and a multilayer ceramic capacitor. The nickel-core ceramic composite powder comprises powder particles with a core-shell structure, where nickel forms the core and ceramic powder is wrapped around the nickel core. The nickel core and the outer shell of the ceramic powder are linked by a silane coupling agent. The slurry is obtained by mixing the nickel-core ceramic composite powder, a solvent, and a resin. The internal electrode of the multilayer ceramic capacitor can be made from the nickel-core ceramic composite powder or a slurry containing the nickel-core ceramic composite powder.

[0089] Compared with nickel powder of the same particle size in the prior art, the nickel core ceramic composite powder provided by the present invention has a higher tap density and a higher coating rate of ceramic powder on the nickel core. Furthermore, the nickel core ceramic composite powder provided by the present invention has better sintering resistance. The slurry containing the above-mentioned nickel core ceramic composite powder provided by the present invention has a lower shrinkage rate, a lower slurry roughness, a higher initial shrinkage temperature, and better sintering resistance. When the above-mentioned nickel core ceramic composite powder and slurry are applied to prepare the internal electrode of a multilayer ceramic capacitor, a multilayer ceramic capacitor with better performance can be obtained. Attached Figure Description

[0090] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0091] Figure 1 A schematic diagram of the core-shell particles of the nickel-core ceramic composite powder provided by the present invention;

[0092] Figure 2 A flowchart illustrating the preparation method of nickel-core ceramic composite powder provided by the present invention;

[0093] Figure 3 A flowchart illustrating the method for preparing the slurry provided by the present invention;

[0094] Figure 4 This is a schematic diagram of the structure of the multilayer ceramic capacitor provided by the present invention.

[0095] Figure Labels

[0096] 1-Inner electrode; 2-Dielectric layer; 3-Outer electrode. Detailed Implementation

[0097] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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. It should be understood that the specific embodiments described herein are only for illustration and explanation of the present invention and are not intended to limit the present invention.

[0098] Any specific numerical values ​​disclosed herein (including the endpoints of numerical ranges) are not limited to their exact values, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Furthermore, with respect to the disclosed numerical ranges, one or more new numerical ranges can be obtained by arbitrarily combining the endpoint values ​​of the range, the endpoint values ​​with specific point values ​​within the range, and the specific point values ​​themselves; these new numerical ranges should also be considered as specifically disclosed herein.

[0099] The terminology used in this disclosure is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” as used in this disclosure are intended to include the plural forms as well. The terms “comprising,” “including,” “containing,” and “having” are inclusive and thus describe the presence of said features, elements, compositions, steps, integers, operations, and / or components, but do not exclude the presence or inclusion of one or more other features, integers, steps, operations, elements, components, and / or sets thereof. Although the open-ended term “comprising” should be understood as a non-limiting term used to describe and claim the various embodiments described in this disclosure, in some aspects it may instead be understood as a more restrictive and limiting term, such as “consisting of” or “substantially consisting of.” Thus, for any given embodiment describing a composition, material, component, element, feature, integer, operation, and / or process step, this disclosure also particularly includes embodiments consisting of or substantially consisting of such compositions, materials, components, elements, features, integers, operations, and / or process steps. In the case of “consisting of…”, the alternative embodiments exclude any additional compositions, materials, components, elements, features, integers, operations and / or process steps. In the case of “essentially composed of…”, any additional compositions, materials, components, elements, features, integers, operations and / or process steps that substantially affect the essential and novel characteristics are excluded from such embodiments. However, any compositions, materials, components, elements, features, integers, operations and / or process steps that do not substantially affect the essential and novel characteristics may be included in the embodiments.

[0100] Any method steps, processes, and operations described in this disclosure should not be construed as necessarily requiring them to be performed in a particular order as discussed or shown, unless explicitly specified. It should also be understood that additional or alternative steps may be used unless otherwise stated.

[0101] In this application, except where expressly stated, any matters or issues not mentioned are directly applicable to those known in the art without any modification. Furthermore, any implementation described in this disclosure may be freely combined with one or more other implementations described in this disclosure, and the resulting technical solutions or concepts shall be considered part of the original disclosure or original record of this application, and should not be regarded as new content not disclosed or anticipated in this disclosure, unless those skilled in the art consider the combination to be clearly unreasonable.

[0102] Unless otherwise stated, the terms used herein have the same meaning as commonly understood by those skilled in the art, and if a term is defined herein and its definition differs from the common understanding in the art, the definition herein shall prevail.

[0103] Unless otherwise stated, when % is mentioned in this document, it means wt.%.

[0104] It is worth noting that the definition of "coverage rate" in this invention specification is the percentage of the area of ​​ceramic powder covering the surface of nickel powder particles to the total surface area of ​​the nickel powder particles.

[0105] First aspect

[0106] See Figure 1 The present invention provides a nickel core ceramic composite powder, the composite powder comprising core-shell particles, the core-shell particles comprising a nickel core and a ceramic layer covering the nickel core, wherein the nickel core and the ceramic layer are bonded together by a coupling agent.

[0107] In some embodiments of the present invention, the coupling agent contains at least silicon, oxygen and hydrogen.

[0108] In some embodiments of the present invention, the coupling agent has the molecular formula (YR). n SiX 4-n , where n is 1 or 2, YR is a non-hydrolyzable organic group, and X is a hydrolyzable group.

[0109] In some embodiments of the present invention, Y is vinyl, amino, epoxy, propylene oxide, or methacryloyloxy, R is a linking group, preferably a direct bond or a C1-C4 alkylene group, such as methylene, -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, and X is a C1-C4 alkoxy group, more preferably ethoxy or methoxy.

[0110] It should be noted that the coupling agent is not retained in its original form in the core-shell particles of the final nickel-core ceramic composite powder. During the preparation of the core-shell particles, the hydrolyzable groups of the coupling agent undergo hydrolysis, generating hydroxyl groups that are directly bonded to silicon atoms. These hydroxyl groups then combine with the nickel core and the surface groups of the ceramic powder.

[0111] In the context of this invention, the coupling agent includes coupling agents that exist as is, i.e., those with the molecular formula (YR). n SiX 4-n The molecules, including the hydrolyzed coupling agent, contain hydrolyzable groups X that have been partially or completely hydrolyzed. In the hydrolyzed coupling agent, hydroxyl groups directly bonded to silicon atoms combine with nickel cores and ceramic powder surface groups.

[0112] Molecular formula (YR) n SiX 4-n The coupling agent can spontaneously hydrolyze to generate YRSi(OH)3. The Y group helps to bond with the organic resin in the slurry system in the later stage. The hydroxyl groups formed after the coupling agent is hydrolyzed can condense with the hydroxyl groups OH or Ni-O on the surface of barium titanate and nickel powder or form hydrogen bonds; thereby stabilizing the coating effect of barium titanate on nickel powder in the slurry.

[0113] In some embodiments of the present invention, the silicon atoms in the coupling agent are connected to the oxygen atoms on the surface of the nickel core via hydrogen bonds through hydroxyl groups.

[0114] In some embodiments of the present invention, silicon atoms in the coupling agent are connected to oxygen atoms on the surface of the ceramic layer via hydrogen bonds through hydroxyl groups.

[0115] In some embodiments of the present invention, the tap density of the composite powder is 2-5 g / cm³. 3 Preferably, it is 2.5–4.5 g / cm³. 3 .

[0116] In some embodiments of the present invention, the particle size of the composite powder is 170–400 nm, preferably 180–380 nm.

[0117] In some embodiments of the present invention, the nickel core has a particle size of 150–300 nm and the ceramic layer has a thickness of 10–100 nm, preferably 20–100 nm.

[0118] This invention provides a nickel-core ceramic composite powder, which has a core-shell structure of powder particles, with nickel as the core and ceramic powder wrapped around the nickel core, and the nickel core and the ceramic powder shell are linked by a coupling agent.

[0119] Compared with nickel powder of the same particle size in the prior art, the nickel core ceramic composite powder provided by the present invention has a higher tap density and a higher coating rate of ceramic powder on the nickel core. Furthermore, the nickel core ceramic composite powder provided by the present invention has better sintering resistance. The slurry containing the above-mentioned nickel core ceramic composite powder provided by the present invention has a lower shrinkage rate, a lower slurry roughness, a higher initial shrinkage temperature, and better sintering resistance. When the above-mentioned nickel core ceramic composite powder and slurry are applied to prepare the internal electrode of a multilayer ceramic capacitor, a multilayer ceramic capacitor with better performance can be obtained.

[0120] Second aspect

[0121] See Figure 2 This invention provides a method for preparing the aforementioned nickel-core ceramic composite powder, the method comprising the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator are mixed and dispersed to obtain the ceramic suspension, and the nickel powder is treated with an alkaline solution, washed with an organic solvent, and dried to obtain modified nickel powder; S2, mixing and dispersing the ceramic suspension and the modified nickel powder to obtain a suspension of nickel powder coated with ceramic; S3, freeze-drying the suspension obtained in step S2 to obtain the composite powder.

[0122] It is worth noting that the preparation order of the above-mentioned ceramic suspension and modified nickel powder does not need to be strictly limited.

[0123] In some embodiments of the present invention, in step S1, each of the organic solvents is independently selected from at least one of n-propanol, isopropanol, and n-butanol.

[0124] In some preferred embodiments of the present invention, in step S1, the amount of ceramic powder added to the ceramic suspension is 40-55 wt.%, the amount of silane coupling agent added is 0.5-5 wt.%, the amount of organic solvent added is 41-56 wt.%, and the amount of alkalinity regulator added is 1-4 wt.%.

[0125] When the amount of silane coupling agent added falls within the above-mentioned preferred range, it is advantageous to fully anchor the coupling agent molecules to the powder surface, resulting in a higher nickel core coating rate.

[0126] In some embodiments of the present invention, in step S1, the molecular formula of the silane coupling agent is (YR). n SiX 4-nWhere n is 1 or 2, YR is a non-hydrolyzable organic group, X is a hydrolyzable group, more preferably Y is vinyl, amino, epoxy, epoxypropoxy or methacryloyloxy, R is a linking group, preferably a direct bond or C1-C4 alkylene group, such as methylene, -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, X is a C1-C4 alkoxy group, more preferably ethoxy or methoxy, and most preferably, the silane coupling agent is at least one selected from γ-aminopropyltriethoxysilane, vinyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

[0127] In some embodiments of the present invention, in step S1, the ceramic powder is at least one of barium titanate, calcium zirconate, strontium zirconate, and zirconium oxide.

[0128] In some embodiments of the present invention, in step S1, the particle size of the ceramic powder is 20-100 nm, preferably 30-90 nm.

[0129] In some embodiments of the present invention, in step S1, the dispersion treatment is carried out by sand milling. More preferably, the sand milling is carried out by zirconium balls with a diameter of 0.02 to 0.1 mm, the linear speed of the sand milling is 10 to 14 m / s, and the sand milling time is 2 to 4 h.

[0130] In some embodiments of the present invention, in step S1, the alkalinity regulator is at least one of di(2-ethylhexyl)amine, hexamethylenediamine, 1,4-butanediamine, and 2-ethylhexylamine.

[0131] Unbound by any particular theory, the inventors believe that the alkaline regulator helps ensure the full hydrolytic coupling of the coupling agent and the stability of Ni-O on the nickel powder surface, thus ensuring effective binding with the coupling agent.

[0132] In some embodiments of the present invention, in step S1, the nickel powder is obtained by physical vapor deposition or chemical vapor deposition, and more preferably, the particle size of the nickel powder is 150-300 nm.

[0133] In some embodiments of the present invention, in step S1, the alkaline solution is an aqueous solution of potassium hydroxide, and more preferably, the pH value of the aqueous solution of potassium hydroxide is 9 to 12.

[0134] Treating nickel powder with the alkaline aqueous solution can fully form Ni-O on the surface of the nickel powder, which is beneficial to enhancing the coupling effect of the coupling agent on the Ni surface.

[0135] In some embodiments of the present invention, step S1, the treatment with alkaline solution includes mixing with the alkaline solution, heating and stirring, and filtering; preferably, in the heating and stirring, the heating temperature is 70-100°C, and the stirring time is 7-12 hours.

[0136] In some embodiments of the present invention, in step S1, each of the organic solvents is independently selected from at least one of n-propanol, isopropanol, and n-butanol.

[0137] In some embodiments of the present invention, in step S2, the mass ratio of the ceramic powder to the modified nickel powder is (6-10):100.

[0138] In some embodiments of the present invention, in step S2, the dispersion treatment is carried out by sand milling, using zirconium balls with a diameter of 0.1 to 0.3 mm, the linear speed of the sand milling is 8 to 10 m / s, and the sand milling time is 2 to 4 hours.

[0139] In some embodiments of the present invention, in step S3, a negative pressure biaxial mixer is used to perform the solvent replacement at 70 to 90°C. More preferably, the negative pressure of the negative pressure biaxial mixer is -0.1 to -0.01 MPa.

[0140] In some embodiments of the present invention, in step S3, a three-roll mill is used for dispersion to obtain the slurry. More preferably, the pressure of the three-roll mill is 15-30 bar, the dispersion temperature is 20-30°C, and the dispersion is performed 3-5 times.

[0141] In some embodiments of the present invention, in step S4, the suspension after solvent replacement is freeze-dried using a freeze dryer, and the cold trap temperature is -70 to -50°C, preferably -65 to -55°C.

[0142] Third aspect

[0143] The present invention provides a slurry, the raw materials of which include: a slurry solvent; a binder; and a nickel core ceramic composite powder. The composite powder includes core-shell particles, the core-shell particles including a nickel core and a ceramic layer covering the nickel core, wherein the nickel core and the ceramic layer are bonded together via a coupling agent.

[0144] In some embodiments of the present invention, the coupling agent contains at least silicon, oxygen and hydrogen.

[0145] In some embodiments of the present invention, the coupling agent has the molecular formula (YR). n SiX 4-n , where n is 1 or 2, YR is a non-hydrolyzable organic group, and X is a hydrolyzable group.

[0146] In some embodiments of the present invention, Y is vinyl, amino, epoxy, propylene oxide, or methacryloyloxy, R is a linking group, preferably a direct bond or a C1-C4 alkylene group, such as methylene, -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, and X is a C1-C4 alkoxy group, more preferably ethoxy or methoxy.

[0147] In some embodiments of the present invention, the silicon atoms in the coupling agent are connected to the oxygen atoms on the surface of the nickel core via hydrogen bonds through hydroxyl groups.

[0148] In some embodiments of the present invention, the slurry solvent is at least one selected from dihydroterpineol acetate, isoborneol acetate, isoamyl acetate, and sec-butyl acetate.

[0149] In some embodiments of the present invention, the content of the slurry solvent in the raw materials of the slurry is 30-40 wt.%, the content of the resin is 3-6 wt.%, and the content of the composite powder is 55-60 wt.%.

[0150] The present invention provides a slurry obtained by mixing the above-mentioned nickel core ceramic composite powder, solvent and binder; in some embodiments of the present invention, the slurry contains an alkaline regulator in addition to the above raw materials.

[0151] The slurry containing the above-mentioned nickel core ceramic composite powder provided by the present invention has a lower shrinkage rate, a lower slurry roughness, a higher initial shrinkage temperature, and better sintering resistance. When the above-mentioned nickel core ceramic composite powder and slurry are applied to prepare the internal electrode of a multilayer ceramic capacitor, a multilayer ceramic capacitor with better performance can be obtained.

[0152] Fourth aspect

[0153] See Figure 3 This invention provides a method for preparing the above-mentioned slurry, the method comprising the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic powder, coupling agent, preferably a silane coupling agent, an organic solvent, and an alkaline regulator are mixed and dispersed to obtain the ceramic suspension, and the nickel powder is treated with an alkaline solution, washed with an organic solvent, and dried to obtain modified nickel powder; S2, mixing and dispersing the ceramic suspension and the modified nickel powder to obtain a suspension of nickel powder coated with ceramic; S3, using a slurry solvent to perform solvent displacement on the suspension obtained in step S2, and after displacement, adding a binder to obtain the slurry.

[0154] It is worth noting that the preparation order of the above-mentioned ceramic suspension and modified nickel powder does not need to be strictly limited.

[0155] It is worth noting that the binder in this invention specification serves to thicken the slurry and improve the dispersion of the composite powder in the slurry or solvent.

[0156] In some embodiments of the present invention, in step S1, each of the organic solvents is independently selected from at least one of n-propanol, isopropanol, and n-butanol.

[0157] In some embodiments of the present invention, in step S1, the molecular formula of the silane coupling agent is (YR). n SiX 4-n Where n is 1 or 2, YR is a non-hydrolyzable organic group, X is a hydrolyzable group, more preferably Y is vinyl, amino, epoxy, epoxypropoxy or methacryloyloxy, R is a linking group, preferably a direct bond or C1-C4 alkylene group, such as methylene, -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, X is a C1-C4 alkoxy group, more preferably ethoxy or methoxy, and most preferably, the silane coupling agent is at least one selected from γ-aminopropyltriethoxysilane, vinyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

[0158] In some embodiments of the present invention, in step S1, the amount of ceramic powder added to the ceramic suspension is 40-55 wt.%, the amount of silane coupling agent added is 0.5-5 wt.%, the amount of organic solvent added is 41-56 wt.%, and the amount of alkalinity regulator added is 1-4 wt.%.

[0159] When the amount of silane coupling agent added falls within the above-mentioned preferred range, it is advantageous to fully anchor the coupling agent molecules to the powder surface, resulting in a higher nickel core coating rate.

[0160] In some embodiments of the present invention, in step S1, the ceramic powder is at least one of barium titanate, calcium zirconate, strontium zirconate, and zirconium oxide.

[0161] In some embodiments of the present invention, in step S1, the particle size of the ceramic powder is 20-100 nm, preferably 30-90 nm.

[0162] In some embodiments of the present invention, in step S1, the dispersion treatment is carried out by sand milling. More preferably, the sand milling is carried out by zirconium balls with a diameter of 0.02 to 0.1 mm, the linear speed of the sand milling is 10 to 14 m / s, and the sand milling time is 2 to 4 h.

[0163] In some embodiments of the present invention, the alkalinity regulator is at least one selected from di(2-ethylhexyl)amine, hexamethylenediamine, 1,4-butanediamine, and 2-ethylhexylamine.

[0164] In some embodiments of the present invention, in step S1, the alkaline solution is an aqueous solution of potassium hydroxide, preferably, the pH value of the aqueous solution of potassium hydroxide is 9 to 12.

[0165] In some embodiments of the present invention, step S1, the treatment with alkaline solution includes mixing with the alkaline solution, heating and stirring, and filtering; preferably, in the heating and stirring, the heating temperature is 70-100°C, and the stirring time is 7-12 hours.

[0166] In some embodiments of the present invention, in step S2, the mass ratio of the ceramic powder to the modified nickel powder is (6-10):100.

[0167] In some embodiments of the present invention, in step S2, the dispersion treatment is carried out by sand milling, using zirconium balls with a diameter of 0.1 to 0.3 mm, the linear speed of the sand milling is 8 to 10 m / s, and the sand milling time is 2 to 4 hours.

[0168] In some embodiments of the present invention, in step S3, a negative pressure biaxial mixer is used to perform the solvent replacement at 70 to 90°C. Preferably, the negative pressure of the negative pressure biaxial mixer is -0.1 to -0.01 MPa.

[0169] In some embodiments of the present invention, in step S3, after solvent replacement is completed, a binder is added and dispersed to obtain the slurry.

[0170] In some embodiments of the present invention, in step S3, the adhesive is at least one of ethyl cellulose resin, phenolic resin, acrylic resin, and polyvinyl butyral resin.

[0171] In some embodiments of the present invention, in step S3, a three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 15-30 bar, the dispersion temperature is 20-30°C, and the dispersion is performed 3-5 times.

[0172] Fifth aspect

[0173] The present invention provides a method for preparing a slurry, the method comprising the following steps: S1, providing the above-mentioned composite powder, or providing nickel core ceramic composite powder obtained by the above method; S2, mixing and dispersing the composite powder, slurry solvent, and binder to obtain a slurry.

[0174] It is worth noting that this pulping method can also be regarded as "reducing the composite powder obtained from the slurry back into the slurry".

[0175] Sixth aspect

[0176] See Figure 4 This invention provides a multilayer ceramic capacitor, which includes an inner electrode 1, a dielectric layer 2, and an outer electrode 3. The inner electrode 1 is disposed on the dielectric layer 2, and the two ends of the inner electrode 1 are connected to the outer electrode 3 by a spacer. The inner electrode 1 is made from the nickel core ceramic composite powder obtained by the above method, or the inner electrode 1 is made from the above slurry, or the inner electrode 1 is made from the slurry obtained by the above method.

[0177] Example 1

[0178] This embodiment provides a method for preparing the above-mentioned nickel-core ceramic composite powder slurry. The method includes the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator are mixed and dispersed to obtain the ceramic suspension, and the nickel powder is mixed with an alkaline solution, heated and stirred, filtered, washed with the organic solvent, and dried to obtain modified nickel powder; S2, the ceramic suspension and the modified nickel powder are mixed and dispersed to obtain a suspension of nickel powder coated with ceramic; S3, the suspension obtained in step S2 is solvent-displaced using a slurry solvent, and a binder is added to the solvent-displaced suspension and dispersed to obtain the slurry;

[0179] Specifically, in step S1 above, 20nm barium titanate is used as the ceramic powder, γ-aminopropyltriethoxysilane is used as the silane coupling agent, n-butanol is used as the organic solvent, and hexamethylenediamine is used as the alkaline regulator. The mass ratio of the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator is 100:1.5:100:1. The nickel powder with a particle size of 200nm, prepared by CVD process, is treated with a potassium hydroxide aqueous solution with a pH of 12 at 70°C, with a stirring speed of 100 rpm and a stirring time of 12 hours. The mixture is heated and stirred at 70°C for 12 hours.

[0180] Specifically, in step S2 above, the mass ratio of ceramic powder to modified nickel powder is 9:100, and zirconium balls with a diameter of 0.3 mm are used for sand milling. The linear speed of sand milling is 10 m / s, and the sand milling time is 2 hours.

[0181] Specifically, in step S3 above, a negative pressure twin-shaft mixer is used to perform solvent replacement at 80°C. The negative pressure of the negative pressure twin-shaft mixer is -0.1 MPa. Ethyl cellulose resin / dihydroterpineol acetate 10:100 is used as a binder. The mass ratio of the binder to the suspension obtained in step S2 is 100:50. A three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 20 bar, the dispersion temperature is 24°C, and the dispersion is performed 5 times.

[0182] The nickel core ceramic composite powder slurry obtained in this embodiment was subjected to performance tests according to the following test examples. The specific test results and some process parameters are recorded in Table 1 below.

[0183] Example 2

[0184] This embodiment provides a method for preparing the above-mentioned nickel-core ceramic composite powder slurry. The method includes the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator are mixed and dispersed to obtain the ceramic suspension, and the nickel powder is mixed with an alkaline solution, heated and stirred, filtered, washed with the organic solvent, and dried to obtain modified nickel powder; S2, the ceramic suspension and the modified nickel powder are mixed and dispersed to obtain a suspension of nickel powder coated with ceramic; S3, the suspension obtained in step S2 is solvent-displaced using a slurry solvent, and a binder is added to the solvent-displaced suspension and dispersed to obtain the slurry;

[0185] Specifically, in step S1 above, 20nm barium titanate is used as the ceramic powder, γ-aminopropyltriethoxysilane is used as the silane coupling agent, n-butanol is used as the organic solvent, and hexamethylenediamine is used as the alkaline regulator. The mass ratio of the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator is 100:1.5:100:1. The nickel powder with a particle size of 200nm, prepared by PVD process, is treated with a potassium hydroxide aqueous solution with a pH of 12 at 70°C, with a stirring speed of 100 rpm and a stirring time of 12 hours. The mixture is heated and stirred at 70°C for 12 hours.

[0186] Specifically, in step S2 above, the mass ratio of ceramic powder to modified nickel powder is 9:100, and zirconium balls with a diameter of 0.3 mm are used for sand milling. The linear speed of sand milling is 10 m / s, and the sand milling time is 2 hours.

[0187] Specifically, in step S3 above, a negative pressure twin-shaft mixer is used to perform solvent replacement at 80°C. The negative pressure of the negative pressure twin-shaft mixer is -0.1 MPa. Ethyl cellulose resin / dihydroterpineol acetate 10:100 is used as a binder. The mass ratio of the binder to the suspension obtained in step S2 is 100:50. A three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 20 bar, the dispersion temperature is 24°C, and the dispersion is performed 5 times.

[0188] The nickel core ceramic composite powder slurry obtained in this embodiment was subjected to performance tests according to the following test examples. The specific test results and some process parameters are recorded in Table 1 below.

[0189] Example 3

[0190] This embodiment provides a method for preparing the above-mentioned nickel-core ceramic composite powder slurry. The method includes the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator are mixed and dispersed to obtain the ceramic suspension, and the nickel powder is mixed with an alkaline solution, heated and stirred, filtered, washed with the organic solvent, and dried to obtain modified nickel powder; S2, the ceramic suspension and the modified nickel powder are mixed and dispersed to obtain a suspension of nickel powder coated with ceramic; S3, the suspension obtained in step S2 is solvent-displaced using a slurry solvent, and a binder is added to the solvent-displaced suspension and dispersed to obtain the slurry;

[0191] Specifically, in step S1 above, 20nm zirconium oxide is used as the ceramic powder, γ-aminopropyltriethoxysilane is used as the silane coupling agent, n-butanol is used as the organic solvent, and hexamethylenediamine is used as the alkaline regulator. The mass ratio of the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator is 100:1.5:100:1. The nickel powder with a particle size of 200nm, prepared by CVD process, is treated with a potassium hydroxide aqueous solution with a pH of 12 at 70°C, with a stirring speed of 100 rpm and a stirring time of 12 hours. The mixture is heated and stirred at 70°C for 12 hours.

[0192] Specifically, in step S2 above, the mass ratio of ceramic powder to modified nickel powder is 9:100, and zirconium balls with a diameter of 0.3 mm are used for sand milling. The linear speed of sand milling is 10 m / s, and the sand milling time is 2 hours.

[0193] Specifically, in step S3 above, a negative pressure twin-shaft mixer is used to perform solvent replacement at 80°C. The negative pressure of the negative pressure twin-shaft mixer is -0.1 MPa. Ethyl cellulose resin / dihydroterpineol acetate 10:100 is used as a binder. The mass ratio of the binder to the suspension obtained in step S2 is 100:50. A three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 20 bar, the dispersion temperature is 24°C, and the dispersion is performed 5 times.

[0194] The nickel core ceramic composite powder slurry obtained in this embodiment was subjected to performance tests according to the following test examples. The specific test results and some process parameters are recorded in Table 1 below.

[0195] Example 4

[0196] This embodiment provides a method for preparing the above-mentioned nickel-core ceramic composite powder slurry. The method includes the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator are mixed and dispersed to obtain the ceramic suspension, and the nickel powder is mixed with an alkaline solution, heated and stirred, filtered, washed with the organic solvent, and dried to obtain modified nickel powder; S2, the ceramic suspension and the modified nickel powder are mixed and dispersed to obtain a suspension of nickel powder coated with ceramic; S3, the suspension obtained in step S2 is solvent-displaced using a slurry solvent, and a binder is added to the solvent-displaced suspension and dispersed to obtain the slurry;

[0197] Specifically, in step S1 above, 20nm barium titanate is used as the ceramic powder, γ-aminopropyltriethoxysilane is used as the silane coupling agent, n-butanol is used as the organic solvent, and hexamethylenediamine is used as the alkaline regulator. The mass ratio of the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator is 100:2:100:1. The nickel powder with a particle size of 150nm, prepared by CVD process, is treated with a potassium hydroxide aqueous solution with a pH of 12 at 70°C, with a stirring speed of 100 rpm and a stirring time of 12 hours. The mixture is heated and stirred at 70°C for 12 hours.

[0198] Specifically, in step S2 above, the mass ratio of ceramic powder to modified nickel powder is 9:100, and zirconium balls with a diameter of 0.3 mm are used for sand milling. The linear speed of sand milling is 10 m / s, and the sand milling time is 2 hours.

[0199] Specifically, in step S3 above, a negative pressure twin-shaft mixer is used to perform solvent replacement at 80°C. The negative pressure of the negative pressure twin-shaft mixer is -0.1 MPa. Ethyl cellulose resin / dihydroterpineol acetate 10:100 is used as a binder. The mass ratio of the binder to the suspension obtained in step S2 is 100:50. A three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 20 bar, the dispersion temperature is 24°C, and the dispersion is performed 5 times.

[0200] The nickel core ceramic composite powder slurry obtained in this embodiment was subjected to performance tests according to the following test examples. The specific test results and some process parameters are recorded in Table 1 below.

[0201] Example 5

[0202] This embodiment provides a method for preparing the above-mentioned nickel-core ceramic composite powder slurry. The method includes the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator are mixed and dispersed to obtain the ceramic suspension, and the nickel powder is mixed with an alkaline solution, heated and stirred, filtered, washed with the organic solvent, and dried to obtain modified nickel powder; S2, the ceramic suspension and the modified nickel powder are mixed and dispersed to obtain a suspension of nickel powder coated with ceramic; S3, the suspension obtained in step S2 is solvent-displaced using a slurry solvent, and a binder is added to the solvent-displaced suspension and dispersed to obtain the slurry;

[0203] Specifically, in step S1 above, 30nm barium titanate is used as the ceramic powder, γ-aminopropyltriethoxysilane is used as the silane coupling agent, n-butanol is used as the organic solvent, and hexamethylenediamine is used as the alkaline regulator. The mass ratio of the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator is 100:2.5:100:1. The nickel powder with a particle size of 250nm, prepared by CVD process, is treated with a potassium hydroxide aqueous solution with a pH of 12 at 70°C, with a stirring speed of 100 rpm and a stirring time of 12 hours. The mixture is heated and stirred at 70°C for 12 hours.

[0204] Specifically, in step S2 above, the mass ratio of ceramic powder to modified nickel powder is 9:100, and zirconium balls with a diameter of 0.3 mm are used for sand milling. The linear speed of sand milling is 10 m / s, and the sand milling time is 2 hours.

[0205] Specifically, in step S3 above, a negative pressure twin-shaft mixer is used to perform solvent replacement at 80°C. The negative pressure of the negative pressure twin-shaft mixer is -0.1 MPa. Ethyl cellulose resin / dihydroterpineol acetate 10:100 is used as a binder. The mass ratio of the binder to the suspension obtained in step S2 is 100:50. A three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 20 bar, the dispersion temperature is 24°C, and the dispersion is performed 5 times.

[0206] The nickel core ceramic composite powder slurry obtained in this embodiment was subjected to performance tests according to the following test examples. The specific test results and some process parameters are recorded in Table 1 below.

[0207] Example 6

[0208] This embodiment provides a method for preparing the above-mentioned nickel-core ceramic composite powder slurry. The method includes the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator are mixed and dispersed to obtain the ceramic suspension, and the nickel powder is mixed with an alkaline solution, heated and stirred, filtered, washed with the organic solvent, and dried to obtain modified nickel powder; S2, the ceramic suspension and the modified nickel powder are mixed and dispersed to obtain a suspension of nickel powder coated with ceramic; S3, the suspension obtained in step S2 is solvent-displaced using a slurry solvent, and a binder is added to the solvent-displaced suspension and dispersed to obtain the slurry;

[0209] Specifically, in step S1 above, 20nm barium titanate is used as the ceramic powder, γ-aminopropyltriethoxysilane is used as the silane coupling agent, n-butanol is used as the organic solvent, and hexamethylenediamine is used as the alkaline regulator. The mass ratio of the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator is 100:3:100:1. The nickel powder with a particle size of 300nm, prepared by CVD process, is treated with a potassium hydroxide aqueous solution with a pH of 12 at 70°C, with a stirring speed of 100 rpm and a stirring time of 12 hours. The mixture is heated and stirred at 70°C for 12 hours.

[0210] Specifically, in step S2 above, the mass ratio of ceramic powder to modified nickel powder is 11:100, and zirconium balls with a diameter of 0.3 mm are used for sand milling. The linear speed of sand milling is 10 m / s, and the sand milling time is 2 hours.

[0211] Specifically, in step S3 above, a negative pressure twin-shaft mixer is used to perform solvent replacement at 80°C. The negative pressure of the negative pressure twin-shaft mixer is -0.1 MPa. Ethyl cellulose resin / dihydroterpineol acetate 10:100 is used as a binder. The mass ratio of the binder to the suspension obtained in step S2 is 100:50. A three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 20 bar, the dispersion temperature is 24°C, and the dispersion is performed 5 times.

[0212] The nickel core ceramic composite powder slurry obtained in this embodiment was subjected to performance tests according to the following test examples. The specific test results and some process parameters are recorded in Table 1 below.

[0213] Example 7

[0214] This embodiment provides a method for preparing the above-mentioned nickel-core ceramic composite powder and slurry. The method includes the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic powder, silane coupling agent, organic solvent and alkaline regulator are mixed and dispersed to obtain the ceramic suspension, and the nickel powder is mixed with an alkaline solution, heated and stirred, filtered, washed with the organic solvent and dried to obtain modified nickel powder; S2, the ceramic suspension and the modified nickel powder are mixed and dispersed to obtain a suspension of nickel powder coated with ceramic; S3, the suspension obtained in step S2 is solvent-displaced using a slurry solvent, and a binder is added to the solvent-displaced suspension and dispersed to obtain the slurry;

[0215] Specifically, in step S1 above, 20nm barium titanate is used as the ceramic powder, γ-aminopropyltriethoxysilane is used as the silane coupling agent, n-butanol is used as the organic solvent, and hexamethylenediamine is used as the alkaline regulator. The mass ratio of the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator is 100:3.5:100:1. The nickel powder with a particle size of 170nm, prepared by CVD process, is treated with a potassium hydroxide aqueous solution with a pH of 12 at 70°C, with a stirring speed of 100 rpm and a stirring time of 12 hours. The mixture is heated and stirred at 70°C for 12 hours.

[0216] Specifically, in step S2 above, the mass ratio of ceramic powder to modified nickel powder is 9:100, and zirconium balls with a diameter of 0.3 mm are used for sand milling. The linear speed of sand milling is 10 m / s, and the sand milling time is 2 hours.

[0217] Specifically, in step S3 above, a negative pressure twin-shaft mixer is used to perform solvent replacement at 80°C. The negative pressure of the negative pressure twin-shaft mixer is -0.1 MPa. Ethyl cellulose resin / dihydroterpineol acetate 10:100 is used as a binder. The mass ratio of the binder to the suspension obtained in step S2 is 100:50. A three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 20 bar, the dispersion temperature is 24°C, and the dispersion is performed 5 times.

[0218] The nickel core ceramic composite powder slurry obtained in this embodiment was subjected to performance tests according to the following test examples. The specific test results and some process parameters are recorded in Table 1 below.

[0219] Example 8

[0220] This embodiment provides a method for preparing the above-mentioned nickel-core ceramic composite powder and slurry. The method includes the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic powder, silane coupling agent, organic solvent and alkaline regulator are mixed and dispersed to obtain the ceramic suspension, and the nickel powder is mixed with an alkaline solution, heated and stirred, filtered, washed with the organic solvent and dried to obtain modified nickel powder; S2, the ceramic suspension and the modified nickel powder are mixed and dispersed to obtain a suspension of nickel powder coated with ceramic; S3, the suspension obtained in step S2 is solvent-displaced using a slurry solvent, and a binder is added to the solvent-displaced suspension and dispersed to obtain the slurry;

[0221] Specifically, in step S1 above, 50nm barium titanate is used as the ceramic powder, γ-aminopropyltriethoxysilane is used as the silane coupling agent, n-butanol is used as the organic solvent, and hexamethylenediamine is used as the alkaline regulator. The mass ratio of the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator is 100:4:100:1. The nickel powder with a particle size of 220nm, prepared by CVD process, is treated with a potassium hydroxide aqueous solution with a pH of 12 at 70°C, with a stirring speed of 100 rpm and a stirring time of 12 hours. The mixture is heated and stirred at 70°C for 12 hours.

[0222] Specifically, in step S2 above, the mass ratio of ceramic powder to modified nickel powder is 13:100, and zirconium balls with a diameter of 0.3 mm are used for sand milling. The linear speed of sand milling is 10 m / s, and the sand milling time is 2 hours.

[0223] Specifically, in step S3 above, a negative pressure twin-shaft mixer is used to perform solvent replacement at 80°C. The negative pressure of the negative pressure twin-shaft mixer is -0.1 MPa. Ethyl cellulose resin / dihydroterpineol acetate 10:100 is used as a binder. The mass ratio of the binder to the suspension obtained in step S2 is 100:50. A three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 20 bar, the dispersion temperature is 24°C, and the dispersion is performed 5 times.

[0224] The nickel core ceramic composite powder slurry obtained in this embodiment was subjected to performance tests according to the following test examples. The specific test results and some process parameters are recorded in Table 1 below.

[0225] Example 9

[0226] This embodiment provides a method for preparing the above-mentioned nickel-core ceramic composite powder slurry. The method includes the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator are mixed and dispersed to obtain the ceramic suspension, and the nickel powder is mixed with an alkaline solution, heated and stirred, filtered, washed with the organic solvent, and dried to obtain modified nickel powder; S2, the ceramic suspension and the modified nickel powder are mixed and dispersed to obtain a suspension of nickel powder coated with ceramic; S3, the suspension obtained in step S2 is solvent-displaced using a slurry solvent, and a binder is added to the solvent-displaced suspension and dispersed to obtain the slurry;

[0227] Specifically, in step S1 above, barium titanate is used as the ceramic powder, γ-aminopropyltriethoxysilane is used as the silane coupling agent, n-butanol is used as the organic solvent, and hexamethylenediamine is used as the alkaline regulator. The mass ratio of the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator is 100:4.5:100:1. The nickel powder with a particle size of 200 nm, prepared by CVD process, is treated with a potassium hydroxide aqueous solution with a pH of 12 at 70°C, with a stirring speed of 100 rpm and a stirring time of 12 hours. The mixture is heated and stirred at 70°C for 12 hours.

[0228] Specifically, in step S2 above, the mass ratio of ceramic powder to modified nickel powder is 9:100, and zirconium balls with a diameter of 0.3 mm are used for sand milling. The linear speed of sand milling is 10 m / s, and the sand milling time is 2 hours.

[0229] Specifically, in step S3 above, a negative pressure twin-shaft mixer is used to perform solvent replacement at 80°C. The negative pressure of the negative pressure twin-shaft mixer is -0.1 MPa. Ethyl cellulose resin / dihydroterpineol acetate 10:100 is used as a binder. The mass ratio of the binder to the suspension obtained in step S2 is 100:50. A three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 20 bar, the dispersion temperature is 24°C, and the dispersion is performed 5 times.

[0230] The nickel core ceramic composite powder slurry obtained in this embodiment was subjected to performance tests according to the following test examples. The specific test results and some process parameters are recorded in Table 1 below.

[0231] Example 10

[0232] This embodiment provides a method for preparing the above-mentioned nickel-core ceramic composite powder slurry. The method includes the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic powder, silane coupling agent, organic solvent and alkaline regulator are mixed and dispersed to obtain the ceramic suspension, and the nickel powder is mixed with an alkaline solution, heated and stirred, filtered, washed with the organic solvent and dried to obtain modified nickel powder; S2, the ceramic suspension and the modified nickel powder are mixed and dispersed to obtain a suspension of nickel powder coated with ceramic; S3, the suspension obtained in step S2 is solvent-displaced using a slurry solvent, and a binder is added to the solvent-displaced suspension and dispersed to obtain the slurry.

[0233] Specifically, in step S1 above, 80nm barium titanate is used as the ceramic powder, γ-aminopropyltriethoxysilane is used as the silane coupling agent, n-butanol is used as the organic solvent, and hexamethylenediamine is used as the alkaline regulator. The mass ratio of the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator is 100:5:100:1. The nickel powder with a particle size of 200nm, prepared by CVD process, is treated with a potassium hydroxide aqueous solution with a pH of 12 at 70°C, with a stirring speed of 100 rpm and a stirring time of 12 hours. The mixture is heated and stirred at 70°C for 12 hours.

[0234] Specifically, in step S2 above, the mass ratio of ceramic powder to modified nickel powder is 7:100, and zirconium balls with a diameter of 0.3 mm are used for sand milling. The linear speed of sand milling is 10 m / s, and the sand milling time is 2 hours.

[0235] Specifically, in step S3 above, a negative pressure twin-shaft mixer is used to perform solvent replacement at 80°C. The negative pressure of the negative pressure twin-shaft mixer is -0.1 MPa. Ethyl cellulose resin / dihydroterpineol acetate 10:100 is used as a binder. The mass ratio of the binder to the suspension obtained in step S2 is 100:50. A three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 20 bar, the dispersion temperature is 24°C, and the dispersion is performed 5 times.

[0236] The nickel core ceramic composite powder slurry obtained in this embodiment was subjected to performance tests according to the following test examples. The specific test results and some process parameters are recorded in Table 1 below.

[0237] Example 11

[0238] This embodiment provides a method for preparing the above-mentioned nickel-core ceramic composite powder. The method includes the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic powder, silane coupling agent, organic solvent and alkaline regulator are mixed and dispersed to obtain the ceramic suspension, and the nickel powder is mixed with an alkaline solution, heated and stirred, filtered, washed with the organic solvent and dried to obtain modified nickel powder; S2, the ceramic suspension and the modified nickel powder are mixed and dispersed to obtain a suspension of nickel powder coated with ceramic; S3, the suspension obtained in step S2 is solvent-displaced using a slurry solvent, and the suspension after solvent displacement is freeze-dried to obtain the nickel-core ceramic composite powder.

[0239] Specifically, in step S1 above, 20nm barium titanate is used as the ceramic powder, γ-aminopropyltriethoxysilane is used as the silane coupling agent, n-butanol is used as the organic solvent, and hexamethylenediamine is used as the alkaline regulator. The mass ratio of the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator is 100:1.5:100:1. The nickel powder with a particle size of 200nm, prepared by CVD process, is treated with a potassium hydroxide aqueous solution with a pH of 12 at 70°C, with a stirring speed of 100 rpm and a stirring time of 12 hours. The mixture is heated and stirred at 70°C for 12 hours.

[0240] Specifically, in step S2 above, the mass ratio of ceramic powder to modified nickel powder is 9:100, and zirconium balls with a diameter of 0.3 mm are used for sand milling. The linear speed of sand milling is 10 m / s, and the sand milling time is 2 hours.

[0241] Specifically, in step S3 above, a negative pressure twin-shaft mixer is used to perform solvent replacement at 80°C, and the negative pressure of the negative pressure twin-shaft mixer is -0.1MPa.

[0242] Specifically, in step S3 above, a freeze dryer is used for freeze drying, and the cold trap temperature is -60°C to -40°C, preferably -60°C.

[0243] The nickel core ceramic composite powder obtained in this embodiment was subjected to performance tests according to the following test examples. The specific test results and some process parameters are recorded in Table 1 below.

[0244] Example 12

[0245] This embodiment provides a method for preparing the above-mentioned nickel-core ceramic composite powder slurry. The method includes the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic powder, silane coupling agent, organic solvent and alkaline regulator are mixed and dispersed to obtain the ceramic suspension, and the nickel powder is mixed with an alkaline solution, heated and stirred, filtered, washed with the organic solvent and dried to obtain modified nickel powder; S2, mixing and dispersing the ceramic suspension and the modified nickel powder to obtain a suspension of nickel powder coated with ceramic; S3, using a slurry solvent to replace the suspension obtained in step S2, adding a binder to the suspension after solvent replacement and dispersing it to obtain the slurry; S4, freeze-drying the slurry obtained in S3 to obtain the nickel-core ceramic composite powder containing the binder; S5, adding a solvent to the nickel-core ceramic composite powder containing the binder obtained in S4 and stirring and dispersing it to reduce it to a slurry.

[0246] In this embodiment, the nickel core ceramic composite powder obtained in Example 1 above is mixed with a slurry solvent at a mass ratio of 1:1 and dispersed in a vertical sand mill to obtain a suspension of nickel core ceramic composite powder.

[0247] Specifically, in step S1 above, 20nm barium titanate is used as the ceramic powder, γ-aminopropyltriethoxysilane is used as the silane coupling agent, n-butanol is used as the organic solvent, and hexamethylenediamine is used as the alkaline regulator. The mass ratio of the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator is 100:1.5:100:1. The nickel powder with a particle size of 200nm, prepared by CVD process, is treated with a potassium hydroxide aqueous solution with a pH of 12 at 70°C, with a stirring speed of 100 rpm and a stirring time of 12 hours. The mixture is heated and stirred at 70°C for 12 hours.

[0248] Specifically, in step S2 above, the mass ratio of ceramic powder to modified nickel powder is 9:100, and zirconium balls with a diameter of 0.3 mm are used for sand milling. The linear speed of sand milling is 10 m / s, and the sand milling time is 2 hours.

[0249] Specifically, in step S3 above, a negative pressure twin-shaft mixer is used for solvent replacement at 80°C, and the negative pressure of the twin-shaft mixer is -0.1 MPa; ethyl cellulose resin / dihydroterpineol acetate 10:100 is used as a binder, and the mass ratio of the binder to the suspension obtained in step S2 is 100:50; a three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 20 bar, the dispersion temperature is 24°C, and the dispersion is performed 5 times.

[0250] Specifically, in step S3 above, a freeze dryer is used for freeze drying, and the cold trap temperature is -60°C to -40°C, preferably -60°C.

[0251] Specifically, in step S5 above, the mass ratio of the nickel core ceramic composite powder containing binder to dihydroterpineol is 1:1, and it is dispersed using a high-speed mixer at a stirring speed of 200 rpm.

[0252] In this embodiment, only nickel core ceramic composite powder containing binder was obtained. This powder could not be reduced to a slurry. The performance of the powder containing binder was tested according to the following test example. The specific test results and some process parameters are recorded in Table 1 below.

[0253] Example 13

[0254] In this embodiment, the nickel core ceramic composite powder obtained in Example 11 above is mixed with a slurry solvent at a mass ratio of 1:1 and dispersed in a vertical sand mill to obtain a suspension of nickel core ceramic composite powder. The vertical sand mill is used to disperse the suspension, employing 0.3mm diameter zirconium balls for milling at a linear speed of 10m / s for 2 hours. The suspension is then mixed with a binder at a mass ratio of 100:50 and dispersed to obtain a nickel core ceramic composite powder slurry. This slurry is obtained using a three-roll mill. Preferably, the pressure of the three-roll mill is 20 bar, the dispersion temperature is 24°C, and the dispersion is performed 5 times. The binder is ethyl cellulose resin / dihydroterpineol acetate at a ratio of 10:100.

[0255] The nickel core ceramic composite powder slurry obtained in this embodiment was subjected to performance tests according to the following test examples. The specific test results and some process parameters are recorded in Table 1 below.

[0256] Example 14

[0257] In this embodiment, the nickel core ceramic composite powder obtained in Example 11 above is mixed with a slurry solvent at a mass ratio of 1:1 and dispersed to obtain a slurry; wherein, a vertical sand mill is used for dispersion to obtain the slurry, preferably, the vertical sand mill uses zirconium balls with a diameter of 0.3 mm for sand milling, the sand milling linear speed is 10 m / s, and the sand milling time is 2 hours.

[0258] The binder-free nickel core ceramic composite powder slurry obtained in this embodiment was subjected to performance tests according to the following test examples. The specific test results and some process parameters are recorded in Table 1 below.

[0259] Comparative Example 1

[0260] This comparative example provides a method for preparing the above-mentioned nickel-core ceramic composite powder slurry. The method includes the following steps: S1, providing a ceramic suspension and unmodified nickel powder, wherein the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator are mixed and dispersed to obtain the ceramic suspension; S2, the ceramic suspension is mixed and dispersed with unmodified nickel powder to obtain a suspension of nickel powder coated with ceramic; S3, the suspension obtained in step S2 is solvent-displaced using a slurry solvent, and a binder is added to the solvent-displaced suspension and dispersed to obtain the slurry.

[0261] Specifically, in step S1 above, 20nm barium titanate is used as the ceramic powder, γ-aminopropyltriethoxysilane is used as the silane coupling agent, n-butanol is used as the organic solvent, and hexamethylenediamine is used as the alkaline regulator. The mass ratio of the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator is 100:1.5:100:1.

[0262] Specifically, in step S2 above, the mass ratio of ceramic powder to unmodified 200nm CVD nickel powder is 9:100, and the powder is milled using zirconium balls with a diameter of 0.3mm at a linear speed of 10m / s for 2 hours.

[0263] Specifically, in step S3 above, a negative pressure twin-shaft mixer is used to perform solvent replacement at 80°C. The negative pressure of the negative pressure twin-shaft mixer is -0.1 MPa. Ethyl cellulose resin / dihydroterpineol acetate 10:100 is used as a binder. A three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 20 bar, the dispersion temperature is 24°C, and the dispersion is performed 5 times.

[0264] The nickel core ceramic composite powder slurry obtained in this comparative example was subjected to performance tests according to the following test examples. The specific test results and some process parameters are recorded in Table 1 below.

[0265] Comparative Example 2

[0266] This comparative example provides a method for preparing the above-mentioned nickel-core ceramic composite powder slurry. The method includes the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic powder and an organic solvent are mixed and dispersed to obtain the ceramic suspension, and the nickel powder is mixed with an alkaline solution, heated and stirred, filtered, washed with the organic solvent, and dried to obtain modified nickel powder; S2, the ceramic suspension and the modified nickel powder are mixed and dispersed to obtain a suspension of nickel powder coated with ceramic; S3, the suspension obtained in step S2 is solvent-displaced using a slurry solvent, and a binder is added to the solvent-displaced suspension and dispersed to obtain the slurry.

[0267] Specifically, in step S1 above, 20nm barium titanate is used as the ceramic powder, no silane coupling agent is used, and n-butanol is used as the organic solvent. The mass ratio of the ceramic powder to the organic solvent is 100:100. The nickel powder with a particle size of 200nm, obtained by CVD process, is treated with a potassium hydroxide aqueous solution with a pH of 12 at 70°C, with a stirring speed of 100rpm and a stirring time of 12h. The mixture is heated and stirred at 70°C for 12h.

[0268] Specifically, in step S2 above, the mass ratio of ceramic powder to modified nickel powder is 9:100, and zirconium balls with a diameter of 0.3 mm are used for sand milling. The linear speed of sand milling is 10 m / s, and the sand milling time is 2 hours.

[0269] Specifically, in step S3 above, a negative pressure twin-shaft mixer is used to perform solvent replacement at 80°C. The negative pressure of the negative pressure twin-shaft mixer is -0.1 MPa. Ethyl cellulose resin / dihydroterpineol acetate 10:100 is used as a binder. A three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 20 bar, the dispersion temperature is 24°C, and the dispersion is performed 5 times.

[0270] The nickel core ceramic composite powder slurry obtained in this comparative example was subjected to performance tests according to the following test examples. The specific test results and some process parameters are recorded in Table 1 below.

[0271] Comparative Example 3

[0272] This comparative example provides a method for preparing the above-mentioned nickel-core ceramic composite powder slurry. The method includes the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic powder, silane coupling agent, organic solvent and alkaline regulator are mixed and dispersed to obtain the ceramic suspension, and the nickel powder is mixed with an alkaline solution, heated and stirred, filtered, washed with the organic solvent and dried to obtain modified nickel powder; S2, the ceramic suspension and the modified nickel powder are mixed and dispersed to obtain a suspension of nickel powder coated with ceramic; S3, the suspension obtained in step S2 is solvent-displaced using a slurry solvent, and a binder is added to the solvent-displaced suspension and dispersed to obtain the slurry.

[0273] Specifically, in step S1 above, 20nm barium titanate is used as the ceramic powder, γ-aminopropyltriethoxysilane is used as the silane coupling agent, n-butanol is used as the organic solvent, and hexamethylenediamine is used as the alkaline regulator. The mass ratio of the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator is 100:0.1:100:1. The nickel powder with a particle size of 200nm, prepared by CVD process, is treated with a potassium hydroxide aqueous solution with a pH of 12 at 70°C, with a stirring speed of 100 rpm and a stirring time of 12 hours. The mixture is heated and stirred at 70°C for 12 hours.

[0274] Specifically, in step S2 above, the mass ratio of ceramic powder to modified nickel powder is 9:100, and zirconium balls with a diameter of 0.3 mm are used for sand milling. The linear speed of sand milling is 10 m / s, and the sand milling time is 2 hours.

[0275] Specifically, in step S3 above, a negative pressure twin-shaft mixer is used to perform solvent replacement at 80°C. The negative pressure of the negative pressure twin-shaft mixer is -0.1 MPa. Ethyl cellulose resin / dihydroterpineol acetate 10:100 is used as a binder. A three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 20 bar, the dispersion temperature is 24°C, and the dispersion is performed 5 times.

[0276] The nickel core ceramic composite powder slurry obtained in this comparative example was subjected to performance tests according to the following test examples. The specific test results and some process parameters are recorded in Table 1 below.

[0277] Comparative Example 4

[0278] This comparative example provides a method for preparing the above-mentioned nickel-core ceramic composite powder slurry. The method includes the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic powder, silane coupling agent, organic solvent and alkaline regulator are mixed and dispersed to obtain the ceramic suspension, and the nickel powder is mixed with an alkaline solution, heated and stirred, filtered, washed with the organic solvent and dried to obtain modified nickel powder; S2, the ceramic suspension and the modified nickel powder are mixed and dispersed to obtain a suspension of nickel powder coated with ceramic; S3, the suspension obtained in step S2 is solvent-displaced using a slurry solvent, and a binder is added to the solvent-displaced suspension and dispersed to obtain the slurry.

[0279] Specifically, in step S1 above, 20nm barium titanate is used as the ceramic powder, γ-aminopropyltriethoxysilane is used as the silane coupling agent, n-butanol is used as the organic solvent, and hexamethylenediamine is used as the alkaline regulator. The mass ratio of the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator is 100:6:100:1. The nickel powder with a particle size of 200nm, prepared by CVD process, is treated with a potassium hydroxide aqueous solution with a pH of 12 at 70°C, with a stirring speed of 100 rpm and a stirring time of 12 hours. The mixture is heated and stirred at 70°C for 12 hours.

[0280] Specifically, in step S2 above, the mass ratio of ceramic powder to modified nickel powder is 9:100, and zirconium balls with a diameter of 0.3 mm are used for sand milling. The linear speed of sand milling is 10 m / s, and the sand milling time is 2 hours.

[0281] Specifically, in step S3 above, a negative pressure twin-shaft mixer is used to perform solvent replacement at 80°C. The negative pressure of the negative pressure twin-shaft mixer is -0.1 MPa. Ethyl cellulose resin / dihydroterpineol acetate 10:100 is used as a binder. A three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 20 bar, the dispersion temperature is 24°C, and the dispersion is performed 5 times.

[0282] The nickel core ceramic composite powder slurry obtained in this comparative example was subjected to performance tests according to the following test examples. The specific test results and some process parameters are recorded in Table 1 below.

[0283] Comparative Example 5

[0284] This comparative example provides a method for preparing the above-mentioned nickel-core ceramic composite powder slurry. The method includes the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic powder, silane coupling agent, organic solvent and alkaline regulator are mixed and dispersed to obtain the ceramic suspension, and the nickel powder is mixed with an alkaline solution, heated and stirred, filtered, washed with the organic solvent and dried to obtain modified nickel powder; S2, the ceramic suspension and the modified nickel powder are mixed and dispersed to obtain a suspension of nickel powder coated with ceramic; S3, the suspension obtained in step S2 is solvent-displaced using a slurry solvent, and a binder is added to the solvent-displaced suspension and dispersed to obtain the slurry.

[0285] Specifically, in step S1 above, 150nm barium titanate is used as the ceramic powder, γ-aminopropyltriethoxysilane is used as the silane coupling agent, n-butanol is used as the organic solvent, and hexamethylenediamine is used as the alkaline regulator. The mass ratio of the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator is 100:1.5:100:1. The nickel powder with a particle size of 200nm, prepared by CVD process, is treated with a potassium hydroxide aqueous solution with a pH of 12 at 70°C, with a stirring speed of 100 rpm and a stirring time of 12 hours. The mixture is heated and stirred at 70°C for 12 hours.

[0286] Specifically, in step S2 above, the mass ratio of ceramic powder to modified nickel powder is 9:100, and zirconium balls with a diameter of 0.3 mm are used for sand milling. The linear speed of sand milling is 10 m / s, and the sand milling time is 2 hours.

[0287] Specifically, in step S3 above, a negative pressure twin-shaft mixer is used to perform solvent replacement at 80°C. The negative pressure of the negative pressure twin-shaft mixer is -0.1 MPa. Ethyl cellulose resin / dihydroterpineol acetate 10:100 is used as a binder. A three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 20 bar, the dispersion temperature is 24°C, and the dispersion is performed 5 times.

[0288] The nickel core ceramic composite powder slurry obtained in this comparative example was subjected to performance tests according to the following test examples. The specific test results and some process parameters are recorded in Table 1 below.

[0289] Comparative Example 6

[0290] This comparative example provides a method for preparing the above-mentioned nickel-core ceramic composite powder slurry. The method includes the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic powder, silane coupling agent, organic solvent and alkaline regulator are mixed and dispersed to obtain the ceramic suspension, and the nickel powder is mixed with an alkaline solution, heated and stirred, filtered, washed with the organic solvent and dried to obtain modified nickel powder; S2, the ceramic suspension and the modified nickel powder are mixed and dispersed to obtain a suspension of nickel powder coated with ceramic; S3, the suspension obtained in step S2 is solvent-displaced using a slurry solvent, and a binder is added to the solvent-displaced suspension and dispersed to obtain the slurry.

[0291] Specifically, in step S1 above, 20nm barium titanate is used as the ceramic powder, γ-aminopropyltriethoxysilane is used as the silane coupling agent, n-butanol is used as the organic solvent, and hexamethylenediamine is used as the alkaline regulator. The mass ratio of the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator is 100:1.5:100:1. The nickel powder with a particle size of 200nm, prepared by CVD process, is treated with a potassium hydroxide aqueous solution with a pH of 12 at 70°C, with a stirring speed of 100 rpm and a stirring time of 12 hours. The mixture is heated and stirred at 70°C for 12 hours.

[0292] Specifically, in step S2 above, the mass ratio of ceramic powder to modified nickel powder is 16:100, and zirconium balls with a diameter of 0.3 mm are used for sand milling. The linear speed of sand milling is 10 m / s, and the sand milling time is 2 hours.

[0293] Specifically, in step S3 above, a negative pressure twin-shaft mixer is used to perform solvent replacement at 80°C. The negative pressure of the negative pressure twin-shaft mixer is -0.1 MPa. Ethyl cellulose resin / dihydroterpineol acetate 10:100 is used as a binder. A three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 20 bar, the dispersion temperature is 24°C, and the dispersion is performed 5 times.

[0294] The nickel core ceramic composite powder slurry obtained in this comparative example was subjected to performance tests according to the following test examples. The specific test results and some process parameters are recorded in Table 1 below.

[0295] Comparative Example 7

[0296] This comparative example provides a method for preparing the above-mentioned nickel-core ceramic composite powder slurry. The method includes the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic powder, silane coupling agent, organic solvent and alkaline regulator are mixed and dispersed to obtain the ceramic suspension, and the nickel powder is mixed with an alkaline solution, heated and stirred, filtered, washed with the organic solvent and dried to obtain modified nickel powder; S2, the ceramic suspension and the modified nickel powder are mixed and dispersed to obtain a suspension of nickel powder coated with ceramic; S3, the suspension obtained in step S2 is solvent-displaced using a slurry solvent, and a binder is added to the solvent-displaced suspension and dispersed to obtain the slurry.

[0297] Specifically, in step S1 above, barium titanate is used as the ceramic powder, γ-aminopropyltriethoxysilane is used as the silane coupling agent, n-butanol is used as the organic solvent, and hexamethylenediamine is used as the alkaline regulator. The mass ratio of the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator is 100:1.5:100:1. The nickel powder with a particle size of 200 nm, prepared by CVD process, is treated with a potassium hydroxide aqueous solution with a pH of 12 at 70°C, with a stirring speed of 100 rpm and a stirring time of 12 hours. The mixture is heated and stirred at 70°C for 12 hours.

[0298] Specifically, in step S2 above, the mass ratio of ceramic powder to modified nickel powder is 4:100, and zirconium balls with a diameter of 0.3 mm are used for sand milling. The linear speed of sand milling is 10 m / s, and the sand milling time is 2 hours.

[0299] Specifically, in step S3 above, a negative pressure twin-shaft mixer is used to perform solvent replacement at 80°C. The negative pressure of the negative pressure twin-shaft mixer is -0.1 MPa. Ethyl cellulose resin / dihydroterpineol acetate 10:100 is used as a binder. A three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 20 bar, the dispersion temperature is 24°C, and the dispersion is performed 5 times.

[0300] The nickel core ceramic composite powder slurry obtained in this comparative example was subjected to performance tests according to the following test examples. The specific test results and some process parameters are recorded in Table 1 below.

[0301] Comparative Example 8

[0302] This comparative example provides a method for preparing the above-mentioned nickel-core ceramic composite powder slurry. The method includes the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic powder, silane coupling agent, organic solvent and alkaline regulator are mixed and dispersed to obtain the ceramic suspension, and the nickel powder is mixed with an alkaline solution, heated and stirred, filtered, washed with the organic solvent and dried to obtain modified nickel powder; S2, the ceramic suspension and the modified nickel powder are mixed and dispersed to obtain a suspension of nickel powder coated with ceramic; S3, the suspension obtained in step S2 is solvent-displaced using a slurry solvent, and a binder is added to the solvent-displaced suspension and dispersed to obtain the slurry.

[0303] Specifically, in step S1 above, barium titanate is used as the ceramic powder, γ-aminopropyltriethoxysilane is used as the silane coupling agent, n-butanol is used as the organic solvent, and hexamethylenediamine is used as the alkaline regulator. The mass ratio of the ceramic powder, silane coupling agent, organic solvent, and alkaline regulator is 100:1.5:100:1. The nickel powder with a particle size of 200 nm, prepared by CVD process, is treated with a potassium hydroxide aqueous solution with a pH of 12 at 70°C, with a stirring speed of 100 rpm and a stirring time of 12 hours. The mixture is heated and stirred at 70°C for 12 hours.

[0304] Specifically, in step S2 above, the mass ratio of ceramic powder to modified nickel powder is 9:100, and zirconium balls with a diameter of 0.3 mm are used for sand milling. The linear speed of sand milling is 10 m / s, and the sand milling time is 2 hours.

[0305] Specifically, in step S3 above, a negative pressure twin-shaft mixer is used to perform solvent replacement at 80°C. The negative pressure of the negative pressure twin-shaft mixer is -0.1 MPa. Ethyl cellulose resin / dihydroterpineol acetate 10:100 is used as a binder. A three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 20 bar, the dispersion temperature is 24°C, and the dispersion is performed 5 times.

[0306] The nickel core ceramic composite powder slurry obtained in this comparative example was subjected to performance tests according to the following test examples. The specific test results and some process parameters are recorded in Table 1 below.

[0307] Comparative Example 9

[0308] This comparative example provides a method for preparing the above-mentioned uncoated nickel powder slurry, the method comprising the following steps: S1, providing modified nickel powder, mixing the nickel powder with an alkaline solution, heating and stirring, filtering, washing with the organic solvent, and drying to obtain modified nickel powder; S2, dispersing the modified nickel powder to obtain a suspension of nickel powder; S3, using a slurry solvent to perform solvent replacement on the suspension obtained in step S2, adding a binder to the suspension after solvent replacement and dispersing it to obtain the slurry.

[0309] Specifically, in step S1 above, a potassium hydroxide aqueous solution with a pH of 12 is used to process nickel powder with a particle size of 200 nm obtained by CVD process at 70°C, with a stirring speed of 100 rpm and a stirring time of 12 hours. The mixture is heated and stirred at 70°C for 12 hours.

[0310] Specifically, in step S2 above, the modified nickel powder is dispersed by sand milling with zirconium balls with a diameter of 0.3 mm, the linear speed of sand milling is 10 m / s, and the sand milling time is 2 hours.

[0311] Specifically, in step S3 above, a negative pressure twin-shaft mixer is used to perform solvent replacement at 80°C. The negative pressure of the negative pressure twin-shaft mixer is -0.1 MPa. Ethyl cellulose resin / dihydroterpineol acetate 10:100 is used as a binder. A three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 20 bar, the dispersion temperature is 24°C, and the dispersion is performed 5 times.

[0312] The uncoated nickel powder slurry obtained in this comparative example was subjected to performance tests according to the following test examples. The specific test results and some process parameters are recorded in Table 1 below.

[0313] Test case

[0314] I. Powder shrinkage rate & initial shrinkage temperature at 1200℃

[0315] Test method: Add 10-15g of nickel paste, place it on a PET film and allow it to level naturally. Heat it in a muffle furnace under air atmosphere at room temperature to 220℃ for 1 hour, and then hold it at 220℃ for 4 hours. Gently crush the dried paste with a grinding rod, accurately weigh 1g of material, apply a pressure of 2MPa without holding the pressure, and after demolding, place the pressed button sample together with the alumina substrate on a nickel grid. Heat it in a tube furnace to remove the adhesive at 350℃ in a N2 atmosphere for 2 hours. Remove the sample when the temperature drops to 50℃ and test it using a Netzsch TMA403. The test conditions are set to nitrogen atmosphere, heating from room temperature to 1200℃ at a heating rate of 10℃ / min. The equipment automatically records the data.

[0316] II. Powder shrinkage rate at 1200℃

[0317] Test method: The sample size shrinkage ratio at 1200℃ at the end of the curve test is as shown above.

[0318] III. Initial Shrinkage Temperature

[0319] Test method: After the above curve test is completed, draw a tangent at the initial inflection point of the curve. The temperature corresponding to the intersection of the tangents is the initial shrinkage temperature.

[0320] IV. Slurry roughness

[0321] Definition: Surface roughness refers to the unevenness of a machined surface, characterized by small gaps and minute peaks and valleys. The distance between two peaks or valleys (wavelength) is very small (less than 1 mm), and it belongs to microscopic geometric shape errors. The smaller the surface roughness, the smoother the surface. Generally, morphological features with a wavelength less than 1 mm are classified as surface roughness.

[0322] Test method:

[0323] Take 0.5g of slurry and place it on a smooth glass plate with a roughness of Ra = 0.01μm or less. Use a 5μm wet film preparation device to prepare the sample and coat it. After drying at 80℃, use a surface roughness tester to test the sample Rz. Take the average value of 8 sets of test data.

[0324] V. Powder tap density

[0325] Definition: Tapped density refers to the mass per unit volume of powder in a container after it has been tapped under specified conditions. It is used to represent the characteristics of powder, such as particle size, packing state, and powder flowability.

[0326] Test method: Take 100g of powder and put it into a special container of the ZJ-1 powder compaction density meter. Vibrate 1800 times with an amplitude of 4cm. Measure the volume after compaction and calculate the density of the compacted powder.

[0327] VI. Powder Drying Method

[0328] Operating method: After solvent replacement, the slurry is freeze-dried using a freeze dryer with a cold trap temperature of -60℃. The evacuation speed of the freeze dryer under no-load should be able to "evacuate from atmospheric pressure to 15Pa within half an hour". Afterward, the powder is completely dried and then taken out.

[0329] The performance test results and some process parameters of the nickel core ceramic composite powder and slurry obtained from the above embodiments and comparative examples are recorded in Table 1 below.

[0330] Table 1 shows the performance test results and some process parameters of the nickel core ceramic composite powder and slurry obtained in each example and comparative example.

[0331]

[0332]

[0333]

[0334]

[0335] The initial shrinkage temperature reflects the degree of contact between nickel powder particles, and can indirectly characterize the degree of coating of nickel powder particles by ceramic powder. The better the coating, the later the initial shrinkage temperature.

[0336] As can be seen from Table 1 above, in Example 1 and Comparative Example 1, the nickel powder surface was not treated with alkaline solution, and the initial shrinkage was brought forward to 513°C. It can be inferred that barium titanate has a poor coating effect on the nickel powder surface. When the nickel powder surface is not treated with alkaline solution, the surface lacks groups for coupling agent to connect and react, so the coating effect of barium titanate is not obvious.

[0337] In Example 1 and Comparative Example 2, no coupling agent was added during the dispersion process in Comparative Example 2. The barium titanate powder was mixed with the nickel powder only through physical adsorption. During the production process, secondary agglomeration and separation were prone to occur, and the coating effect of ceramic powder on nickel powder could not be achieved. Therefore, compared with Comparative Example 1, the shrinkage temperature of the powder was further advanced to 420°C.

[0338] Comparative Examples 3 and 4 were compared to confirm the effect of adding coupling agent. When the amount added was reduced to 0.1%, the coupling effect was poor. Compared with conventionally dispersed powder, the shrinkage temperature was only 39°C lower. As the proportion of coupling agent added gradually increased, the initial shrinkage temperature tended to be lower. However, adding more coupling agent is not always better. When the amount exceeds a certain level, excessive coupling agent will self-couple, making the ceramic powder more prone to agglomeration before dispersing and coating the nickel powder, affecting dispersion and coating properties. Therefore, after adding 6% coupling agent in Comparative Example 4, the initial shrinkage temperature dropped to below 500°C.

[0339] In Example 1 and Comparative Example 5, the barium titanate powder particle size was 150 nm instead of 20 nm because the 200 nm nickel powder particle size is comparable to the 150 nm barium titanate powder particle size. Even if the coupling agent has a coating effect, the coating effect will be worse due to the unsuitable particle size matching, and the initial shrinkage temperature will be moved forward to 512 °C. Therefore, the preferred barium titanate particle size is 20 nm.

[0340] In Comparative Examples 6 and 7, under the action of nickel powder surface treatment and coupling agent, the amount of barium titanate powder added was increased from 9% to 16% and decreased to 4%. As the proportion of barium titanate powder added gradually increases, the initial shrinkage temperature will gradually move towards higher temperatures. However, considering that the finished paste needs to be applied to the printing electrode of MLCC, in order to ensure the continuity of the electrode, the amount of barium titanate powder added is preferably 9%.

[0341] In Comparative Example 8, vinyltriethoxysilane was used as a coupling agent. When organic amine was used as an alkaline hydrolysis aid, it could also achieve the effect of coupling and coating. In the other examples and the comparative example, γ-aminopropyltriethoxysilane was used, in which the Y group is an amino group, which can form an alkaline environment to facilitate hydrolysis and coupling. In terms of coupling agents, γ-aminopropyltriethoxysilane and other coupling agents with their own amino groups are preferred.

[0342] In Comparative Example 9, no ceramic powder was added as a sintering inhibitor during the entire dispersion process. Therefore, regardless of whether the nickel powder was surface treated or not, the initial shrinkage temperature of the uncoated nickel powder was around 400℃. Based on the initial shrinkage temperature of 405℃ of the nickel powder in Comparative Example 9, the coating effect of ceramic powder compared with nickel powder was judged. The higher the coating degree, the higher the initial shrinkage temperature.

[0343] Examples 2 to 10 investigated the effects of different production methods, nickel powder particle size, ceramic powder type, ceramic powder addition amount, and coupling agent addition amount on the coating effect. Using the initial shrinkage temperature as the standard for coating effect, the following conclusions were drawn: CVD nickel powder has a more concentrated particle size and fewer fine particles than PVD nickel powder, resulting in lower sintering activity and helping to delay the initial shrinkage temperature of the powder sintering. However, due to the use of full ceramic powder coating, the direct difference in the initial shrinkage temperature between different powders was small, and the initial shrinkage temperature of all powders could reach above 800℃. Compared with other ceramic powders, zirconium oxide and barium titanate can achieve the same coating effect when the particle size is consistent. At the same time, the smaller the particle size of the ceramic powder, the less mass needs to be added. When the particle size reaches 100nm or more, the coating effect is worse when the particle size is larger due to the problem of particle size matching. However, in the actual dispersion process, the smaller the particle size, the more difficult it is to disperse. Therefore, the preferred particle size of ceramic powder is 20-50nm. The addition of silane coupling agent within the range of 1.5%-5% shows a good coating effect. The initial shrinkage temperature of the coated powder can be above 800℃.

[0344] Examples 11 to 14: Example 11 yields dried powder with no significant change in coating properties; Example 13 allows for the addition of a binder for redispersing to obtain a finished slurry; Example 12, due to the presence of resin in the dried powder, it adheres to the powder surface, and the addition of a solvent cannot completely dissolve the resin, resulting in the inability to obtain a slurry with the corresponding properties; Example 14, without the addition of a binder for redispersing, results in an unstable slurry prone to secondary agglomeration and stratification.

[0345] It is worth noting that, as can be seen from Table 1 above, PVD has a large particle size distribution and many small powder particles. The smaller the powder, the greater the sintering activity and the higher the requirements for coating effect. CVD has a concentrated particle size, which is beneficial to the coating of ceramic powder.

[0346] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims. Furthermore, specific examples have been used in the specification to illustrate the principles and implementation methods of the present invention. The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention, and the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A nickel-core ceramic composite powder, characterized in that, The composite powder comprises core-shell particles, wherein the core-shell particles comprise a nickel core and a ceramic layer covering the nickel core, wherein the nickel core and the ceramic layer are bonded together via a coupling agent.

2. The nickel-core ceramic composite powder according to claim 1, characterized in that, The coupling agent has the molecular formula (YR). n SiX 4-n Where n is 1 or 2, YR is a non-hydrolyzable organic group, and X is a hydrolyzable group; Preferably, Y is vinyl, amino, epoxy, propylene oxide, or methacryloyloxy, R is a linking group, preferably a direct bond or a C1-C4 alkylene group, such as methylene, -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, and X is a C1-C4 alkoxy group, more preferably ethoxy or methoxy.

3. The nickel-core ceramic composite powder according to claim 1, characterized in that, In the core-shell particles, the silicon atoms in the coupling agent are connected to the oxygen atoms on the surface of the nickel core via hydrogen bonds through hydroxyl groups or undergo condensation with the hydroxyl or oxygen groups on the surface of the nickel core; And / or, the silicon atoms in the coupling agent are connected to the oxygen atoms on the surface of the ceramic layer via hydrogen bonds through hydroxyl groups or undergo condensation with the hydroxyl or oxygen groups on the surface of the ceramic layer.

4. The nickel-core ceramic composite powder according to any one of claims 1 to 3, characterized in that, The tap density of the composite powder is 2-5 g / cm³. 3 Preferably, it is 2.5–4.5 g / cm³. 3 ; And / or, the particle size of the composite powder is 170-400 nm, preferably 180-380 nm.

5. The nickel-core ceramic composite powder according to any one of claims 1 to 3, characterized in that, The nickel core has a particle size of 150–300 nm, and the ceramic layer has a thickness of 10–100 nm, preferably 20–100 nm.

6. A method for preparing nickel-core ceramic composite powder as described in any one of claims 1 to 5, characterized in that, The method includes the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic suspension is obtained by mixing and dispersing ceramic powder, coupling agent, preferably silane coupling agent, organic solvent and alkaline regulator, and the modified nickel powder is obtained by treating with alkaline solution, washing with organic solvent and drying. S2, the ceramic suspension is mixed and dispersed with the modified nickel powder to obtain a suspension of nickel powder coated with ceramic. S3, freeze-dry the suspension obtained in step S2 to obtain the composite powder.

7. The method according to claim 6, characterized in that, Includes at least one of the following features: Preferably, in step S1, the organic solvent is at least one selected from n-propanol, isopropanol, and n-butanol; Preferably, in step S1, the amount of ceramic powder added to the ceramic suspension is 40-55 wt.%, the amount of coupling agent, preferably silane coupling agent, added is 0.5-5 wt.%, the amount of organic solvent added is 41-56 wt.%, and the amount of alkalinity regulator added is 1-4 wt.%. Preferably, in step S1, the molecular formula of the silane coupling agent is (YR). n SiX 4-n Where n is 1 or 2, YR is a non-hydrolyzable organic group, X is a hydrolyzable group, more preferably, Y is vinyl, amino, epoxy, epoxypropoxy or methacryloyloxy, R is a linking group, preferably a direct bond or C1-C4 alkylene group, such as methylene, -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, X is a C1-C4 alkoxy group, more preferably ethoxy or methoxy, and most preferably, the silane coupling agent is at least one selected from γ-aminopropyltriethoxysilane, vinyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane; Preferably, in step S1, the ceramic powder is at least one of barium titanate, calcium zirconate, strontium zirconate, and zirconium oxide; Preferably, in step S1, the particle size of the ceramic powder is 20-100 nm, more preferably 30-90 nm; Preferably, in step S1, the dispersion treatment is carried out by sand milling; more preferably, the sand milling is carried out by zirconium balls with a diameter of 0.02 to 0.1 mm, the linear velocity of the sand milling is 10 to 14 m / s, and the sand milling time is 2 to 4 h. Preferably, in step S1, the alkalinity regulator is at least one of di(2-ethylhexyl)amine, hexamethylenediamine, 1,4-butanediamine, and 2-ethylhexylamine; Preferably, in step S1, the nickel powder is obtained by physical vapor deposition or chemical vapor deposition. More preferably, the particle size of the nickel powder is 150-300 nm.

8. The method according to claim 6, characterized in that, Includes at least one of the following features: Preferably, in step S1, the alkaline solution is an aqueous solution of potassium hydroxide; more preferably, the pH value of the aqueous solution of potassium hydroxide is 9 to 12. Preferably, in step S1, the treatment with alkaline solution includes mixing with the alkaline solution, heating and stirring, and filtering; preferably, in the heating and stirring, the heating temperature is 70-100°C, and the stirring time is 7-12 hours. Preferably, in step S1, each organic solvent is independently selected from at least one of n-propanol, isopropanol, and n-butanol.

9. The method according to claim 6, characterized in that, In step S2, the mass ratio of the ceramic powder to the modified nickel powder is (6-10):

100. And / or, in step S2, the dispersion treatment is carried out by sand milling, using zirconium balls with a diameter of 0.1 to 0.3 mm, the linear speed of the sand milling is 8 to 10 m / s, and the sand milling time is 2 to 4 hours.

10. The method according to claim 6, characterized in that, Includes at least one of the following features: Preferably, in step S3, a negative pressure twin-shaft mixer is used to perform the solvent replacement at 70-90°C; more preferably, the negative pressure of the negative pressure twin-shaft mixer is -0.1 to -0.01 MPa. Preferably, in step S3, a three-roll mill is used for dispersion to obtain the slurry. More preferably, the pressure of the three-roll mill is 15-30 bar, the dispersion temperature is 20-30°C, and the dispersion is performed 3-5 times.

11. The method according to claim 6, characterized in that, In step S4, a freeze dryer is used for freeze drying, and the cold trap temperature is -70 to -50°C, preferably -65 to -55°C.

12. A slurry, characterized in that, The raw materials for the slurry include: Slurry solvent; Adhesives; Nickel-core ceramic composite powder, the composite powder comprising core-shell particles, the core-shell particles comprising a nickel core and a ceramic layer covering the nickel core, wherein the nickel core and the ceramic layer are bonded together via a coupling agent.

13. The slurry according to claim 12, characterized in that, The coupling agent contains at least silicon, oxygen, and hydrogen.

14. The slurry according to claim 13, characterized in that, The coupling agent has the molecular formula (YR). n SiX 4-n Where n is 1 or 2, YR is a non-hydrolyzable organic group, and X is a hydrolyzable group; Preferably, Y is a vinyl, amino, or methacryloyloxy group, R is a linking group, preferably a direct bond or a C1-C4 alkylene group, such as methylene, -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, and X is a C1-C4 alkoxy group, preferably ethoxy or methoxy.

15. The slurry according to any one of claims 12 to 14, characterized in that, The silicon atoms in the coupling agent are connected to the oxygen atoms on the surface of the nickel core via hydrogen bonds through hydroxyl groups or condensed with the hydroxyl or oxygen groups on the surface of the nickel core. And / or, the silicon atoms in the coupling agent are connected to the oxygen atoms on the surface of the ceramic layer via hydrogen bonds through hydroxyl groups or undergo condensation with the hydroxyl or oxygen groups on the surface of the ceramic layer.

16. The slurry according to any one of claims 12 to 14, characterized in that, Includes at least one of the following features: The slurry solvent is at least one of dihydroterpineol acetate, isoborneol acetate, isoamyl acetate, and sec-butyl acetate. And / or, the adhesive is at least one of ethyl cellulose resin, polyvinyl butyral resin, and acrylic resin; And / or, in the raw materials of the slurry, the content of the slurry solvent is 30-40 wt.%, the content of the binder is 3-6 wt.%, and the content of the composite powder is 55-60 wt.

17. A method for preparing a slurry as described in any one of claims 12 to 16, characterized in that, The method includes the following steps: S1, providing a ceramic suspension and modified nickel powder, wherein the ceramic suspension is obtained by mixing and dispersing ceramic powder, coupling agent, preferably silane coupling agent, organic solvent and alkaline regulator, and the modified nickel powder is obtained by treating the nickel powder with an alkaline solution, washing it with an organic solvent and drying it. S2, the ceramic suspension is mixed and dispersed with the modified nickel powder to obtain a suspension of nickel powder coated with ceramic. S3, the suspension obtained in step S2 is solvent-displaced using a slurry solvent. After the displacement is complete, a binder is added to obtain the slurry.

18. The method according to claim 17, characterized in that, Includes at least one of the following features: Preferably, in step S1, each organic solvent is independently selected from at least one of n-propanol, isopropanol, and n-butanol; Preferably, in step S1, the molecular formula of the silane coupling agent is (YR). n SiX 4-n Where n is 1 or 2, YR is a non-hydrolyzable organic group, X is a hydrolyzable group, more preferably, Y is vinyl, amino, epoxy, epoxypropoxy or methacryloyloxy, R is a linking group, preferably a direct bond or C1-C4 alkylene group, such as methylene, -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, X is a C1-C4 alkoxy group, more preferably ethoxy or methoxy, and most preferably, the silane coupling agent is at least one selected from γ-aminopropyltriethoxysilane, vinyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane; Preferably, in step S1, the amount of ceramic powder added to the ceramic suspension is 40-55 wt.%, the amount of silane coupling agent added is 0.5-5 wt.%, the amount of organic solvent added is 41-56 wt.%, and the amount of alkaline regulator added is 1-4 wt.%. Preferably, in step S1, the ceramic powder is at least one of barium titanate, calcium zirconate, strontium zirconate, and zirconium oxide. Preferably, in step S1, the particle size of the ceramic powder is 20-100 nm, more preferably 30-90 nm; Preferably, in step S1, the dispersion treatment is carried out by sand milling; more preferably, the sand milling is carried out by zirconium balls with a diameter of 0.02 to 0.1 mm, the linear velocity of the sand milling is 10 to 14 m / s, and the sand milling time is 2 to 4 h. Preferably, the alkalinity regulator is at least one of di(2-ethylhexyl)amine, hexamethylenediamine, 1,4-butanediamine, and 2-ethylhexylamine.

19. The method according to claim 17, characterized in that, Includes at least one of the following features: In step S1, the alkaline solution is an aqueous solution of potassium hydroxide, preferably with a pH value of 9 to 12. And / or, in step S1, the treatment with alkaline solution includes mixing with the alkaline solution, heating and stirring, and filtering; preferably, in the heating and stirring, the heating temperature is 70-100°C, and the stirring time is 7-12 hours. And / or, in step S1, the organic solvent is at least one of n-propanol, isopropanol, and n-butanol.

20. The method according to claim 17, characterized in that, In step S2, the mass ratio of the ceramic powder to the modified nickel powder is (6-10):

100. And / or, in step S2, the dispersion treatment is carried out by sand milling, using zirconium balls with a diameter of 0.1 to 0.3 mm, the linear speed of the sand milling is 8 to 10 m / s, and the sand milling time is 2 to 4 hours.

21. The method according to claim 17, characterized in that, Includes at least one of the following features: In step S3, after the solvent replacement is completed, the binder is added and dispersed to obtain the slurry; And / or, in step S3, a negative pressure twin-shaft mixer is used to perform the solvent replacement at 70-90°C. Preferably, the negative pressure of the negative pressure twin-shaft mixer is -0.1 to -0.01 MPa. And / or, in step S3, the adhesive is at least one of ethyl cellulose resin, phenolic resin, acrylic resin, and polyvinyl butyral resin; And / or, in step S3, a three-roll mill is used for dispersion to obtain the slurry. Preferably, the pressure of the three-roll mill is 15-30 bar, the dispersion temperature is 20-30°C, and the dispersion is performed 3-5 times.

22. A method for preparing a slurry, characterized in that, The method includes the following steps: S1, providing the composite powder as described in any one of claims 1 to 5, or providing the nickel core ceramic composite powder obtained by the method as described in any one of claims 6 to 11; S2, the composite powder, slurry solvent, and binder are mixed and dispersed to obtain a slurry.

23. A multilayer ceramic capacitor, characterized in that, The multilayer ceramic capacitor includes an inner electrode (1), a dielectric layer (2) and an outer electrode (3). The inner electrode (1) is disposed on the dielectric layer (2), and the two ends of the inner electrode (1) are connected to the outer electrode (3) through a partition. The inner electrode (1) is prepared using a nickel core ceramic composite powder as described in any one of claims 1 to 5, or the inner electrode (1) is prepared using a nickel core ceramic composite powder obtained by any one of claims 6 to 11, or the inner electrode (1) is prepared using a slurry as described in any one of claims 12 to 16, or the inner electrode (1) is prepared using a slurry obtained by any one of claims 17 to 21, or the inner electrode (1) is prepared using a slurry as described in claim 22.

Images