Lead-free composite glass powder for side insulation of resistor disc and preparation method of lead-free composite glass powder
By combining vanadate-molybdate lead-free glass with nano-aluminum nitride core-shell structure, the problems of matrix damage and poor interface compatibility of lead-free insulating glass powder during high-temperature sintering are solved, forming a highly reliable and electrically breakdown resistant insulating layer, which improves the dielectric strength and long-term stability of the resistor sheet.
Patent Information
- Application Number
- CN202511858451.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-10
- Publication Date
- 2026-01-20
AI Technical Summary
Existing lead-free insulating glass powder is prone to damaging the resistor substrate during high-temperature sintering, has insufficient thermal stability and mechanical strength, and poor interfacial compatibility with functional fillers, which leads to microcracks and performance degradation in the insulation layer.
Using vanadate-molybdate lead-free glass as the matrix and combining it with a core-shell structure of functional fillers, a dense and strongly adherent insulating layer is formed through a composite design of nano-aluminum nitride core and borosilicate lead-free glass shell. The multivalent state characteristics and low-temperature melting characteristics of vanadium-molybdenum oxide are utilized to enhance mechanical strength and chemical compatibility.
It achieves high-reliability insulation protection, suppresses ion migration and current leakage, improves dielectric strength and long-term service stability, enhances thermal stability and mechanical strength, and adapts to long-term operation under high pressure and high temperature environments.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of electronic components, in particular to a lead-free composite glass powder for insulating the side surface of a resistor disc and a preparation method thereof. BACKGROUND
[0002] The resistor disc is a core component of overvoltage protection equipment in a power system. The side surface of the resistor disc needs to be covered with a high-reliability insulating layer to block the transverse leakage path of the current, prevent surface flashover, and ensure long-term stable operation of the equipment under high voltage and harsh environment. At present, the insulating layer is usually made of glass powder through coating and sintering process.
[0003] Traditional insulating glass powder generally uses lead-containing glass system, which has excellent low-temperature sintering characteristics, good wettability, high dielectric strength, and a matching coefficient of thermal expansion with the resistor body substrate. However, lead and its compounds are highly toxic and pose environmental pollution risks. With the increasingly stringent global environmental regulations, developing high-performance lead-free insulating glass powder has become an urgent technical problem in this field.
[0004] Existing lead-free research mainly focuses on borosilicate, phosphate, and vanadate systems, but still faces many challenges in practical applications. First, many lead-free systems need high sintering temperatures (usually higher than 600℃) to achieve sufficient densification, which is inconsistent with the thermal tolerance of the resistor disc substrate, easily leading to damage to the microstructure of the substrate and degradation of electrical performance. Second, pure lead-free glass systems often lag behind lead-containing systems in terms of thermal stability, mechanical strength, and interface compatibility with functional fillers, resulting in micro-cracks in the insulating layer, insufficient adhesion, and severe performance degradation under long-term electric field and humid heat aging environment. In addition, the introduction of functional fillers to improve performance easily causes interface reactions with the substrate glass or uneven dispersion, which in turn introduces defects and becomes a weak point of electric field concentration.
[0005] Therefore, there is an urgent need in the art for a new lead-free composite glass powder to fundamentally replace traditional lead-containing glass. SUMMARY
[0006] To solve the above problems, the present application provides a lead-free composite glass powder for insulating the side surface of a resistor disc and a preparation method thereof.
[0007] In a first aspect, the present application provides a lead-free composite glass powder for insulating the side surface of a resistor disc, which adopts the following technical solution: A lead-free composite glass powder for insulating the side surface of a resistor disc, comprising the following raw materials by weight: 90-110 parts of a base glass powder and 10-30 parts of a functional filler, wherein the base glass powder is a vanadate-molybdate-based lead-free glass.
[0008] By adopting the technical scheme, the vanadate-molybdate system is used as the base glass, and the composite optimization of the functional filler is used, so that excellent comprehensive performance is exhibited in the application of the resistance sheet side insulation: based on the low-temperature melting characteristics of vanadium-molybdenum oxide glass and the structural enhancement effect of the functional filler, a dense and strong adhesion insulation layer can be formed in the sintering process, effectively blocking the lateral migration of current; at the same time, the system produces an interface coupling effect with the functional filler through the multi-valence state characteristics of the transition metal oxides in the vanadium-molybdenum glass network, not only significantly improves the mechanical strength and thermal stability of the insulation layer, but also enhances the chemical compatibility with the resistance body surface, inhibits the interface ion diffusion, and thus realizes the unification of high reliability insulation protection and long-term service stability.
[0009] Optionally, the base glass powder comprises the following raw materials by weight: V2O545-75 parts, TeO215-38 parts, MoO315-30 parts, Bi2O38-23 parts.
[0010] By adopting the technical scheme, through the multi-component synergistic effect of V2O5, MoO3, TeO2 and Bi2O3, a stable glass network structure is formed. The structure has low-temperature fluidity and high chemical stability, and exhibits excellent wettability and densification ability in the sintering process; wherein V2O5 and MoO3 as network formers, through the polarization effect with TeO2 and the modification effect of Bi2O3, significantly reduce the softening point of the glass and enhance the wettability of the melt to the substrate; at the same time, the multi-valence state characteristics of vanadium and molybdenum ions produce a self-regulating charge balance effect at the interface, effectively inhibiting ion migration and improving the dielectric strength of the insulation layer, and the introduction of Bi2O3 further strengthens the interfacial bonding force between the glass phase and the functional filler, finally forming a high-reliability insulation layer that is dense, strongly adhered and can withstand electric field impact and thermal cycling.
[0011] Optionally, the functional filler is a core-shell structure nanoparticle, the core of which is a nano-aluminum nitride powder, and the shell is a borosilicate lead-free glass layer that is chemically compatible with the base glass powder and has low-temperature sintering activity.
[0012] By adopting the technical scheme, the aluminum nitride core, with its high thermal conductivity and insulation, serves as an efficient heat dissipation channel and dielectric reinforcing phase, effectively dispersing and dissipating local heat accumulation and electric field concentration; the outer coated borosilicate lead-free glass shell has excellent chemical compatibility and sintering activity with the base glass powder, promoting the interdiffusion of the shell and the base glass during the heat treatment process and forming a strong interfacial bonding, not only avoiding filler agglomeration and achieving stress matching, but also protecting the aluminum nitride core from high-temperature oxidation failure, finally building a uniformly dispersed and firmly interfaced multifunctional reinforcing phase in the composite insulation layer, significantly improving the thermal stability, mechanical strength and electric breakdown resistance of the insulation layer.
[0013] Optionally, the particle size D50 of the nano-aluminum nitride ranges from 50 to 150 nm.
[0014] By adopting the above technical solution, the nano-scale size provides a very high specific surface area, promotes the densification of the heat conduction path and the uniformization of the electric field distribution; at the same time, this size range not only avoids the agglomeration effect easily caused by too small particle size, but also ensures the good dispersibility and stability of the particles in the glass melt, and its size matches the size of the glass network structure, effectively filling the micro defects in the glass phase and blocking the crack propagation path; during the sintering process, the nano-aluminum nitride, by virtue of its size effect and high surface activity, produces strong interfacial interaction with the wrapped borosilicate shell layer and the substrate glass, not only greatly improving the thermal conductivity and mechanical toughness of the composite layer, but also enhancing the dielectric performance by optimizing the interfacial polarization behavior, ultimately improving the insulation layer Optionally, the functional filler preparation comprises the following steps: S1. Disperse the nano-aluminum nitride powder in anhydrous ethanol solution with a pH of 3, add polyethylene glycol as a dispersant, and obtain a stable nano-aluminum nitride suspension by ultrasonic treatment; S2. Dissolve tetraethyl orthosilicate in anhydrous ethanol to form solution A for standby, dissolve bismuth nitrate and boric acid in 75wt% ethanol aqueous solution to form solution B, slowly add solution B to solution A while stirring, continue stirring at room temperature for 2-3h to obtain Bi2O3-B2O3-SiO2 glass precursor sol; S3. Slowly add the nano-aluminum nitride suspension obtained in step S1 to the glass precursor sol obtained in step S2, continue stirring at 55-65℃ for 3-5h, and keep the pH of the system between 3-4 during the process, centrifuge and wash after the reaction, and dry to obtain the precursor powder; S4. Heat treat the obtained precursor powder, increase the temperature to 350℃ at a rate of 3-5℃ / min and keep for 1h, then continue to increase the temperature to 550-600℃ at a rate of 3-5℃ / min and keep for 2h, and obtain the functional filler after cooling in the furnace.
[0015] By adopting the technical scheme, in the acid alcohol system, the directional adsorption of polyethylene glycol effectively eliminates the surface energy barrier of the nano-aluminum nitride, ensuring the monodispersity of the core; through the synergistic hydrolysis-condensation of tetraethyl orthosilicate, bismuth nitrate and boric acid, a ternary glass precursor compatible with the matrix glass is formed, and the molecular level mixing characteristics lay a foundation for the formation of a dense amorphous shell layer at low temperature; in the coupling reaction of strictly controlled pH and temperature, the glass precursor is uniformly coated on the aluminum nitride core through electrostatic condensation with the surface hydroxyl group, forming a pre-solidified shell layer with controllable thickness; the step-by-step heat treatment strategy realizes the densification transformation of the shell layer from amorphous to glassy by rearranging the molecular chain segments and eliminating organic matter, while avoiding the oxidative damage of aluminum nitride, and finally obtains a core-shell filler with high interfacial bonding strength, dense shell and excellent thermal stability, which can fully play the multiple core roles of interface enhancement, thermal conductivity regulation and dielectric optimization in the composite insulation layer.
[0016] Optionally, the mass ratio of the nano-aluminum nitride, anhydrous ethanol and polyethylene glycol in step S1 is 1:(15-25):(0.08-0.12); In step S2, the mass ratio of tetraethyl orthosilicate, bismuth nitrate, boric acid, anhydrous ethanol and ethanol solution is 1:(1.2-1.8):(0.25-0.35):(3.0-4.0):(1.8-2.2); In step S3, the weight ratio of the nano-aluminum nitride suspension to the glass precursor sol is 1:(2.5-4.0).
[0017] By adopting the above technical scheme, the controllable construction and performance optimization of the core-shell structure on the microscale are realized: the specific solid-liquid ratio and the amount of dispersant in S1 ensure the monodispersity and colloidal stability of the nano-aluminum nitride in the medium, providing an ideal single-core reaction template for uniform coating; the accurate molar ratio of each component in S2 controls the hydrolysis-condensation kinetics of the precursor, prompting Bi2O3, B2O3 and SiO2 to be compounded at the molecular level to generate a glass composition with low-temperature sintering activity and a matching thermal expansion coefficient with the matrix; the precise feeding ratio of the core and the shell precursor in S3 realizes the optimal control of the coating thickness, so that the final shell layer can completely isolate the contact between aluminum nitride and oxygen, and also does not excessively increase the interfacial thermal resistance. Finally, a functional core-shell structure filler with complete coating and good interface fusion is obtained.
[0018] In a second aspect, the application provides a preparation method of a lead-free composite glass powder for insulating the side surface of a resistance sheet, which adopts the following technical scheme: A preparation method of a lead-free composite glass powder for insulating the side surface of a resistance sheet, comprising the following steps: The raw materials of the base glass powder are mixed uniformly, and then melted at 900-1100 DEG C for 1-3 hours, water-quenched, crushed, and ball-milled to a particle size D50 of 1-5 microns; The obtained functional filler and base glass powder are mixed and stirred uniformly in a certain proportion to obtain the lead-free composite glass powder for the side insulation of the resistance sheet.
[0019] By using the above technical scheme, the base glass powder is prepared by high-temperature melting-water quenching process, so that the raw materials are fully reacted to form a homogeneous glass network structure, and then the functional filler is compounded to realize lead-free and performance optimization: the atomic diffusion of the raw materials during melting forms stable chemical bonds, water quenching quickly solidifies to retain amorphous structure, and micron-sized particles with high specific surface area are obtained after ball milling to provide a uniform dispersion matrix for the functional filler; the functional filler and the base glass powder are tightly combined through physical coating and chemical adsorption, and a three-dimensional heat-conducting-insulating network is constructed, which not only utilizes the high thermal conductivity of the functional filler to improve the heat dissipation capacity of the side surface of the resistance sheet and avoids the performance degradation caused by local overheating, but also blocks the electric leakage channel through the continuous wrapping of the glass phase, significantly enhances the side insulation reliability, and at the same time, the lead-free formula meets the environmental protection requirements, finally obtains a composite glass powder with high-efficiency heat management, excellent insulation performance and environmental adaptability, which can significantly improve the long-term operation stability of the resistance sheet under high pressure and high temperature conditions.
[0020] In a third aspect, the application provides a lead-free composite glass powder for the side insulation of a resistance sheet, which comprises the following steps: The lead-free composite glass powder of any one of claims 1-6 is mixed with an organic carrier in a mass ratio of 60-70:30-40 to prepare an insulation paste; the organic carrier is composed of terpineol and ethyl cellulose; the insulation paste is coated on the side surface of the resistance sheet, and after drying, sintering is performed at 450-500 DEG C for 10-30 minutes in an air atmosphere to form a dense insulation layer.
[0021] By adopting the above technical solution, this application process achieves precise coating and low-temperature densification of insulating materials on the side of the resistor sheet by mixing composite glass powder with a specific organic carrier to form a slurry. The carrier system composed of terpineol and ethyl cellulose provides excellent rheological properties and spreadability, ensuring that the slurry can uniformly cover complex contour surfaces and form a defect-free pre-coating during the drying process. During the low-temperature sintering process in an air atmosphere, the organic carrier is completely decomposed and removed. At the same time, the matrix glass powder and functional filler undergo synergistic melting-flow-bonding. The low softening point of vanadium-molybdate glass enables it to form a continuous glass phase at a lower temperature. Through interfacial interfusion with the borosilicate layer on the surface of the core-shell filler, a strongly bonded three-dimensional network structure is constructed. This process ultimately forms a dense, non-porous, and highly adhesive insulating layer. The uniformly dispersed nano-aluminum nitride core inside effectively inhibits the propagation of thermal stress cracks and optimizes the electric field distribution, giving the side of the resistor sheet a protective layer with high insulation strength, excellent mechanical reliability, and long-term thermal stability.
[0022] In summary, this application has the following beneficial effects: 1. Based on the low softening point of vanadium-molybdate glass and the charge self-balancing effect of the multi-valence state of transition metals, this application forms a dense and defect-free insulating layer during sintering, which effectively suppresses ion migration and current leakage. At the same time, the core-shell structure design of functional fillers strengthens the interfacial bonding force, significantly improving the dielectric strength and long-term service stability of the resistor sheet.
[0023] 2. In this application, a three-dimensional heat conduction network is preferably constructed using a nano-aluminum nitride core, which greatly improves the heat dissipation capacity and thermal shock resistance of the insulation layer. Its nanoscale effect and the stress matching effect of the glass shell layer jointly inhibit crack propagation, giving the insulation layer high mechanical toughness and crack resistance. Attached Figure Description
[0024] Figure 1 The morphological characteristics of the glass powder prepared in Example 1 under a microscope; Figure 2 The morphological features of the glass powder prepared in Example 1 are further magnified under a scanning electron microscope. Detailed Implementation
[0025] The following detailed description of this application is provided in conjunction with the embodiments. It should be noted that: unless otherwise specified, the conditions in the following embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following embodiments are all from commercially available sources.
[0026] Preparation examples of raw materials and / or intermediates Preparation Example 1 A functional filler is prepared by the following steps: S1. 5 kg of nano-aluminum nitride powder was dispersed in 100 kg of anhydrous ethanol solution with pH of 3, 0.2 kg of polyethylene glycol was added as a dispersant, and ultrasonic treatment was continued for 15 min to obtain a stable nano-aluminum nitride suspension; S2. 10 kg of tetraethyl orthosilicate was dissolved in 35 kg of anhydrous ethanol and mixed and stirred uniformly to form solution A for standby, 15 kg of bismuth nitrate and 3 kg of boric acid were dissolved in 20 kg of 75 wt% ethanol aqueous solution to form solution B, solution B was slowly added to solution A while stirring, and the reaction was continuously stirred at room temperature for 2.5 h to obtain a Bi2O3-B2O3-SiO2 glass precursor sol; S3. 10 kg of the nano-aluminum nitride suspension prepared in step S1 was slowly added to 30 kg of the glass precursor sol, and the mixed system was placed in a 60°C water bath and continuously stirred for 4 h, and the pH of the system was maintained between 3-4 during the reaction, after the reaction was completed, the precursor powder was obtained by centrifugal washing and drying; S4. The obtained precursor powder was heat treated, the temperature was increased to 350°C at a rate of 3°C / min, and the temperature was maintained for 1 h, then the temperature was further increased to 580°C at a rate of 5°C / min, and the temperature was maintained for 2 h, and the functional filler was obtained after the furnace was cooled down; the particle size D50 of the nano-aluminum nitride ranges from 50-150 nm.
[0027] Preparation Example 2 A functional filler, the preparation comprising the following steps: S1. 5 kg of nano-aluminum nitride powder was dispersed in 125 kg of anhydrous ethanol solution with pH of 3, 0.4 kg of polyethylene glycol was added as a dispersant, and ultrasonic treatment was continued for 15 min to obtain a stable nano-aluminum nitride suspension; S2. 10 kg of tetraethyl orthosilicate was dissolved in 30 kg of anhydrous ethanol and mixed and stirred uniformly to form solution A for standby, 18 kg of bismuth nitrate and 2.5 kg of boric acid were dissolved in 18 kg of 75 wt% ethanol aqueous solution to form solution B, solution B was slowly added to solution A while stirring, and the reaction was continuously stirred at room temperature for 2 h to obtain a Bi2O3-B2O3-SiO2 glass precursor sol; S3. 10 kg of the nano-aluminum nitride suspension prepared in step S1 was slowly added to 25 kg of the glass precursor sol, and the mixed system was placed in a 55°C water bath and continuously stirred for 5 h, and the pH of the system was maintained between 3-4 during the reaction, after the reaction was completed, the precursor powder was obtained by centrifugal washing and drying; S4. The obtained precursor powder was heat treated, the temperature was increased to 350°C at a rate of 5°C / min, and the temperature was maintained for 1 h, then the temperature was further increased to 550°C at a rate of 5°C / min, and the temperature was maintained for 2 h, and the functional filler was obtained after the furnace was cooled down, the particle size D50 of the nano-aluminum nitride ranges from 50-150 nm.
[0028] Preparation Example 3 A functional filler, the preparation comprising the following steps: S1. 5 kg of nano-aluminum nitride powder is ultrasonically dispersed in 75 kg of anhydrous ethanol solution with pH of 3, 0.6 kg of polyethylene glycol is added, and ultrasonic treatment is continued for 15 min to obtain a stable nano-aluminum nitride suspension; S2. 10 kg of tetraethyl orthosilicate is dissolved in 40 kg of anhydrous ethanol to form solution A, 12 kg of bismuth nitrate and 3.5 kg of boric acid are dissolved in 22 kg of 75 wt% ethanol aqueous solution to form solution B, solution B is slowly added to solution A under stirring, and stirring is continued at room temperature for 3 h to obtain a Bi2O3-B2O3-SiO2 glass precursor sol; S3. 10 kg of the nano-aluminum nitride suspension prepared in step S1 is slowly added to 40 kg of the glass precursor sol, and the mixed system is placed in a 65°C water bath for continuous stirring for 3 h, and the pH of the system is maintained at 3-4 during the reaction, after the reaction, centrifugal washing and drying are performed to obtain a precursor powder; S4. The obtained precursor powder is heat treated, the temperature is increased to 350°C at a rate of 4°C / min, and the temperature is maintained for 1 h, then the temperature is further increased to 600°C at a rate of 5°C / min, and the temperature is maintained for 2 h, and the functional filler is obtained after the furnace is cooled, and the particle size D50 of the nano-aluminum nitride is in the range of 50-150 nm.
[0029] Preparation Example 4 A borosilicate glass powder, the preparation comprising the following steps: S1. 10 kg of tetraethyl orthosilicate is dissolved in 35 kg of anhydrous ethanol to form solution A, 15 kg of bismuth nitrate and 3 kg of boric acid are dissolved in 20 kg of 75 wt% ethanol aqueous solution to form solution B, solution B is slowly added to solution A under stirring, and stirring is continued at room temperature for 2.5 h to obtain a Bi2O3-B2O3-SiO2 glass precursor sol; S2. 30 kg of the glass precursor sol prepared in S1 is placed in a 60°C water bath for continuous stirring for 4 h, and the pH of the system is maintained at 3-4 during the reaction, after the reaction, centrifugal washing and drying are performed to obtain a precursor powder; S3. The obtained precursor powder is heat treated, the temperature is increased to 350°C at a rate of 3°C / min, and the temperature is maintained for 1 h, then the temperature is further increased to 580°C at a rate of 5°C / min, and the temperature is maintained for 2 h, and the functional filler is obtained after the furnace is cooled.
[0030] Example Example 1 A lead-free composite glass powder for the side insulation of a resistance sheet, the preparation comprising the following steps: Take 6 kg V2O5, 2.6 kg TeO2, 2.3 kg MoO3 and 1.5 kg Bi2O3 mixed uniformly, melt at 900-1100℃ for 1-3h, water quenching, drying at 105℃ for 12h, the dried glass block is initially broken and then ball milled to a particle size D50 of 1-5μm; Take 2 kg of the functional filler prepared in Preparation Example 1, 10 kg of the base glass powder, mix and stir uniformly to obtain the lead-free composite glass powder for the side insulation of the resistance sheet, the particle morphology under the microscope is shown in Figure 1 、 Figure 2 .
[0031] Example 2 A lead-free composite glass powder for the side insulation of the resistance sheet, the preparation comprises the following steps: Take 4.5 kg V2O5, 3.8 kg TeO2, 3.0 kg MoO3 and 0.8 kg Bi2O3 mixed uniformly, melt at 900-1100℃ for 1-3h, water quenching, drying at 105℃ for 12h, the dried glass block is initially broken and then ball milled to a particle size D50 of 1-5μm; Take 3 kg of the functional filler prepared in Preparation Example 1, 9 kg of the base glass powder, mix and stir uniformly to obtain the lead-free composite glass powder for the side insulation of the resistance sheet.
[0032] Example 3 A lead-free composite glass powder for the side insulation of the resistance sheet, the preparation comprises the following steps: Take 7.5 kg V2O5, 1.5 kg TeO2, 1.5 kg MoO3 and 2.3 kg Bi2O3 mixed uniformly, melt at 900-1100℃ for 1-3h, water quenching, drying at 105℃ for 12h, the dried glass block is initially broken and then ball milled to a particle size D50 of 1-5μm; Take 1 kg of the functional filler prepared in Preparation Example 1, 11 kg of the base glass powder, mix and stir uniformly to obtain the lead-free composite glass powder for the side insulation of the resistance sheet.
[0033] Example 4 A lead-free composite glass powder for the side insulation of the resistance sheet, which is different from Example 1 in that the functional filler prepared in Preparation Example 2 is used in this example.
[0034] Example 5 A lead-free composite glass powder for the side insulation of the resistance sheet, which is different from Example 1 in that the functional filler prepared in Preparation Example 3 is used in this example.
[0035] Comparative Example Comparative Example 1 A lead-free composite glass powder for side insulation of a resistance chip, which is different from Example 1 in that no functional filler is added in this example.
[0036] Comparative Example 2 A lead-free composite glass powder for side insulation of a resistance chip, which is different from Example 1 in that no functional filler is added, but 0.5 kg of nano-aluminum nitride powder and 1.5 kg of borosilicate lead-free glass powder prepared in Preparation Example 4 are added respectively, and the nano-aluminum nitride powder is treated by polyethylene glycol dispersion.
[0037] Comparative Example 3 A lead-free composite glass powder for side insulation of a resistance chip, which is different from Example 1 in that an equal amount of aluminum oxide (D50 = 1 μm) is used to replace the functional filler.
[0038] Application Example Application Example 1 Application of a lead-free composite glass powder for side insulation of a resistance chip, specifically comprising the following steps: The lead-free composite glass powder prepared in Example 1 is mixed with an organic carrier in a mass ratio of 65:35 to prepare an insulation paste, and the organic carrier is composed of terpineol and ethyl cellulose in a weight ratio of 95:5; the insulation paste is coated on the side of a D42 zinc oxide resistance chip, and after drying, sintering is performed at 480°C for 20 minutes in an air atmosphere to form a dense insulation layer.
[0039] Application Examples 2-8 Application of a lead-free composite glass powder for side insulation of a resistance chip, which is different from Application Example 1 in that the composite glass powders prepared in Examples 2-5 and Comparative Examples 1-3 are used respectively in this application example.
[0040] Performance detection test Detection method / test method Dielectric strength: detected according to the method shown in ASTM D149 "Standard Test Methods for Dielectric Breakdown Voltage and Dielectric Strength of Electrical Insulating Materials at Power Frequencies". Aging test: after 1000 h at 85°C / 85% RH, test the resistance change rate according to the method shown in IEC 60216-1-2013.
[0041] Table 1 Test detection results
[0042] It can be seen from application examples 1-3 and application example 6 in combination with Table 1 that the test data of application examples 1-3 are all better than that of application example 6, which indicates that the addition of the functional filler helps to optimize the microstructure of the glass powder, increase the difficulty of ion migration, thereby enhancing the dielectric strength of the material and reducing the resistance change rate during the aging process.
[0043] It can be seen from application examples 1-3 and application example 7 in combination with Table 1 that the test data of application examples 1-3 are all better than that of application example 7, the functional filler prepared in the application has a core-shell structure prepared by specific raw material ratio and preparation process, which is more effective than simple physical mixing, the core-shell structure ensures the firm interface bonding between the filler and the matrix and the effective protection of the aluminum nitride core, avoids the interface defects and oxidation of aluminum nitride that may be caused by simple mixing, thereby achieving more excellent insulation reliability and durability.
[0044] It can be seen from application examples 1-3 and application example 8 in combination with Table 1 that the test data of application examples 1-3 are all better than that of application example 8, which indicates that the functional filler in the application has advantages in improving the dielectric strength and resisting aging.
[0045] It can be seen from application examples 1-5 in combination with Table 1 that the addition of the functional filler prepared in the application can significantly improve the dielectric strength of the lead-free composite glass powder for the side insulation of the resistor disc, reduce the resistance change rate during the aging process, enhance the insulation performance and stability of the material, and prolong the service life of the material.
[0046] The specific embodiments are merely an explanation of the application, and are not a limitation of the application, and those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, as long as the modifications are within the scope of the claims of the application.
Claims
1. A lead-free composite glass powder for resistance element side insulation, characterized by, The lead-free composite glass powder comprises the following raw materials by weight: 90-110 parts of a base glass powder, and 10-30 parts of a functional filler, wherein the base glass powder is a vanadate-molybdate system lead-free glass; the base glass powder comprises the following raw materials by weight: 45-75 parts of V2O5, 15-38 parts of TeO2, 15-30 parts of MoO3, and 8-23 parts of Bi2O3; and the functional filler is a nano-particle with a core-shell structure, wherein the core is nano-aluminum nitride powder, and the shell is a borosilicate lead-free glass layer which is chemically compatible with the base glass powder and has low-temperature sintering activity.
2. A lead-free composite glass powder for the lateral insulation of a resistor element according to claim 1, characterized in that: The nano-aluminum nitride has a particle size D50 ranging from 50 nm to 150 nm.
3. A lead-free composite glass powder for the lateral insulation of a resistor element according to claim 1, characterized in that The preparation of the functional filler comprises the following steps: S1. dispersing the nano-aluminum nitride powder in anhydrous ethanol solution with a pH of 3, adding polyethylene glycol as a dispersant, and obtaining a stable nano-aluminum nitride suspension through ultrasonic treatment; S2. dissolving tetraethyl orthosilicate in anhydrous ethanol to form solution A, dissolving bismuth nitrate and boric acid in 75 wt% ethanol water solution to form solution B, slowly adding solution B to solution A while stirring, continuously stirring at room temperature for 2-3 hours, and obtaining a Bi2O3-B2O3-SiO2 glass precursor sol; S3. slowly adding the nano-aluminum nitride suspension obtained in step S1 to the glass precursor sol obtained in step S2, continuously stirring at 55-65°C for 3-5 hours, keeping the pH of the system between 3 and 4 during the process, centrifuging and washing after the reaction, and drying to obtain a precursor powder; S4. heat-treating the obtained precursor powder, increasing the temperature to 350°C at a rate of 3-5°C / min, keeping the temperature for 1 hour, then continuously increasing the temperature to 550-600°C at a rate of 3-5°C / min, keeping the temperature for 2 hours, and obtaining the functional filler after cooling in the furnace.
4. A lead-free composite glass powder for the lateral insulation of a resistor element according to claim 3, characterized in that: In step S1, the mass ratio of the nano-aluminum nitride, anhydrous ethanol, and polyethylene glycol is 1:(15-25):(0.08-0.12); In step S2, the mass ratio of tetraethyl orthosilicate, bismuth nitrate, boric acid, anhydrous ethanol, and ethanol water solution is 1:(1.2-1.8):(0.25-0.35):(3.0-4.0):(1.8-2.2); In step S3, the weight ratio of the nano-aluminum nitride suspension to the glass precursor sol is 1:(2.5-4.0).
5. A method of producing a lead-free composite glass powder for the side insulation of a resistor chip according to any one of claims 1 to 4, characterized in that, The preparation comprises the following steps: mixing the raw materials of the base glass powder uniformly, melting at 900-1100°C for 1-3 hours, water quenching, crushing, and ball milling to a particle size D50 of 1-5 μm; mixing the obtained functional filler and base glass powder in a proper proportion, stirring uniformly, and obtaining the lead-free composite glass powder for the side insulation of a resistance sheet.
6. Use of a lead-free composite glass powder for the side insulation of a resistor disc, characterized in that: mixing the lead-free composite glass powder of any one of claims 1-4 with an organic carrier in a mass ratio of 60-70:30-40 to prepare an insulation paste, wherein the organic carrier is composed of terpineol and ethyl cellulose; coating the insulation paste on the side of a resistance sheet, drying, and sintering at 450-500°C in an air atmosphere for 10-30 minutes to form a dense insulation layer.