Composition for preparing high-stability direct current resistance sheet, high-stability direct current resistance sheet, and preparation method and application thereof

Abstract

The application relates to the technical field of lightning protection equipment manufacturing, and discloses a composition for preparing a high-stability direct-current resistance sheet, the high-stability direct-current resistance sheet, a preparation method and application thereof. The composition contains the following components: ZnO, Bi2O3, Sb2O3, Co2O3, MnO2, Cr2O3, SiO2, NiO, SnO2, BN, Al(NO3)3.H2O and silver glass powder. The resistance sheet prepared by using the composition has high stability. In addition, the method can avoid resistance sheet grain coarsening, increase the non-uniformity of the internal microstructure and increase the number of pores; the excellent basic electrical performance of the direct-current resistance sheet can be ensured. Meanwhile, the method can make the electrical performance change of the resistance sheet under current impact and the continuous direct-current electric field smaller, and the performance is more stable.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lightning protection device manufacturing, in particular to a composition for preparing a high-stability DC resistance disc, a high-stability DC resistance disc and a preparation method and application thereof. BACKGROUND

[0002] Compared with AC transmission lines, DC transmission lines have low line cost, small line active loss and stable operation. The ±500kV DC transmission line has become an important line for inter-provincial DC transmission, and the DC lightning arrester determines the insulation protection level of the line and bears the responsibility of protecting the line from lightning strikes.

[0003] Zinc oxide resistance discs are the core components of DC lightning arresters, but most of the resistance discs manufactured by domestic manufacturers are mainly applicable to AC and cannot be applied to DC or have poor effects. Under DC voltage, the conduction mechanism of the resistance disc is significantly different from that under AC voltage. The forward and reverse volt-ampere characteristic curves of the zinc oxide resistance disc under DC voltage will asymmetrically drift after an impact, which causes the traditional AC zinc oxide resistance disc to quickly age, heat collapse and even fail under DC voltage, and cannot meet the requirements of DC transmission on the aging performance of the resistance disc.

[0004] Therefore, there is an urgent need for a DC zinc oxide resistance disc with high stability while ensuring basic electrical parameters, thereby providing technical support for lightning disaster protection of DC transmission lines.

[0005] Currently, in the preparation of DC zinc oxide resistance discs, compared with the preparation of AC zinc oxide resistance discs, DC coating and DC diffusion processes are often introduced to improve the aging resistance (stability) of the resistance disc, so as to reduce the uneven distribution of Bi-rich phases in the grain boundary layer, the increase of pores and other phenomena caused by the evaporation of a large amount of Bi2O3 during high-temperature sintering above 1100℃ and heat treatment at about 800℃.

[0006] CN101503292A discloses a DC zinc oxide resistance disc formula composed of additives and main material ZnO, and the characteristics are as follows: the weight percentage of each additive and zinc oxide is as follows: Bi2O3: 4.0%-4.9%; Sb2O3: 3.0%-4.0%; SiO2: 0.5%-1.0%; Co2O3: 2.0%-3.0%; Cr2O3: 0.50%-0.80%; MnCO3: 0.50%-0.80%; NiO: 0.70%-0.90%; aluminum nitrate: 0.03%-0.05%; glass powder: 0.10%-0.20%; B2O3: 0.07%-0.10%; ZnO: 85.0%-88.0%.

[0007] For example, CN105427977A discloses a high-performance DC zinc oxide resistor disc, which is characterized by comprising the following components and their mole fractions: ZnO 90-98 parts, Bi2O3 0.5-7 parts, Sb2O3 0.1-10 parts, Co2O3 0.1-2 parts, SiO2 0.1-5 parts, MnO2 0.1-5 parts, Cr2O3 0.1-5 parts, NiO 0.1-4 parts, B2O3 0.1-1 part, Al(NO3)3·9H2O 0.01-0.6 part, V2O5 0.01-0.5 part, CeO2 0.01-0.5 part, and silver glass powder 0.05-0.5 part.

[0008] However, the above prior art has the defects of further roughening of the internal microstructure of the resistor disc, reduction of the grain boundary barrier, and increase of the macroscopic leakage current, and the preparation process of the resistor disc is complex, time-consuming, energy-consuming, and high in production cost, thereby affecting the production efficiency. SUMMARY

[0009] The present application aims to overcome the above-mentioned defects of the prior art and provide a DC zinc oxide resistor disc with high stability under the premise of ensuring basic electrical properties.

[0010] To achieve the above-mentioned purpose, the first aspect of the present application provides a composition for preparing a high-stability DC resistor disc, which comprises the following components:

[0011] ZnO, Bi2O3, Sb2O3, Co2O3, MnO2, Cr2O3, SiO2, NiO, SnO2, BN, Al(NO3)3·H2O, and silver glass powder;

[0012] The content of ZnO is 87-95 mol%, the content of Bi2O3 is 0.7-2.5 mol%, the content of Sb2O3 is 0.2-2.5 mol%, the content of Co2O3 is 0.5-2 mol%, the content of MnO2 is 0.2-1.7 mol%, the content of Cr2O3 is 0.3-0.8 mol%, the content of SiO2 is 0.3-1 mol%, the content of NiO is 0.5-1.8 mol%, the content of SnO2 is 0.1-0.8 mol%, the content of BN is 0.3-2 mol%, the content of Al(NO3)3·H2O is 0.003-0.02 mol%, and the content of silver glass powder is 0.005-0.20 mol%, based on the total mole amount of the composition;

[0013] the content of SnO2 is not higher than the content of Bi2O3; the content of SnO2 is not higher than the content of Sb2O3; and

[0014] K is defined as (molar percentage content of Bi2O3+molar percentage content of SnO2+molar percentage content of BN), and K is 1.6-4.5.

[0015] The second aspect of the present application provides a method for preparing a high-stability direct-current resistance sheet, which is performed by using the composition described in the aforementioned first aspect, and comprises:

[0016] (1) performing first grinding on each component in the composition to obtain product I;

[0017] (2) mixing product I with a binder and then performing drying treatment to obtain product II; performing tabletting treatment on product II to obtain product III;

[0018] (3) sequentially performing degassing pre-burning, high-temperature sintering, insulation layer coating and heat treatment on product III to obtain product IV;

[0019] (4) performing electrode coating on product IV to obtain the high-through-flow direct-current resistance sheet.

[0020] The third aspect of the present application provides a high-stability direct-current resistance sheet prepared by the method described in the aforementioned first aspect.

[0021] The fourth aspect of the present application provides an application of the high-stability direct-current resistance sheet described in the aforementioned third aspect in lightning protection equipment.

[0022] The resistance sheet prepared by using the composition provided by the present application has high stability.

[0023] By using the method provided by the present application, the resistance sheet can be prevented from grain coarsening, increase in internal microstructure inhomogeneity and increase in porosity; and the excellent basic electrical properties of the direct-current resistance sheet can be ensured. Meanwhile, the method provided by the present application can effectively eliminate metastable defects in the resistance sheet, obtain a more stable grain boundary structure, and make the electrical properties of the resistance sheet change less under current impact and continuous direct-current electric field, and the performance of the resistance sheet more stable.

[0024] In addition, the method provided by the present application also has the advantages of simple process, low energy consumption and high production efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a microstructure SEM diagram of the resistance sheet in Example 1 provided by the present application;

[0026] Figure 2 is a schematic diagram of the crystal form of bismuth oxide at the grain boundary of the microstructure of the product before heat treatment provided by the present application;

[0027] Figure 3is a schematic diagram of the bismuth oxide crystal form at the grain boundary of the microstructure of the product after heat treatment provided by the present application;

[0028] Figure 4 is a front view of a preferred saggar provided by the present application;

[0029] Figure 5 is a schematic diagram of a hollow grid side of a preferred saggar provided by the present application. DETAILED DESCRIPTION

[0030] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The ranges and values are approximations that are already sufficiently accurate for practical purposes. It is not actually to be expected that the endpoints of the ranges and values will be literally exact, and thus, the endpoints of the ranges and values are included in the range where appropriate. It is therefore to be understood that the endpoints are provided as a separate category that is included in the range. It is also understood that the other categories are not precluded based on the fact that the endpoints are included in the range.

[0031] As described previously, the first aspect of the present application provides a composition for preparing a high-stability direct-current resistor, the composition comprising the following components:

[0032] ZnO, Bi2O3, Sb2O3, Co2O3, MnO2, Cr2O3, SiO2, NiO, SnO2, BN, Al(NO3)3·H2O, silver glass powder;

[0033] The content of the ZnO is 87-95 mol%, the content of the Bi2O3 is 0.7-2.5 mol%, the content of the Sb2O3 is 0.2-2.5 mol%, the content of the Co2O3 is 0.5-2 mol%, the content of the MnO2 is 0.2-1.7 mol%, the content of the Cr2O3 is 0.3-0.8 mol%, the content of the SiO2 is 0.3-1 mol%, the content of the NiO is 0.5-1.8 mol%, the content of the SnO2 is 0.1-0.8 mol%, the content of the BN is 0.3-2 mol%, the content of the Al(NO3)3·H2O is 0.003-0.02 mol%, and the content of the silver glass powder is 0.005-0.20 mol%, based on the total molar amount of the composition;

[0034] The content of the SnO2 is not higher than the content of the Bi2O3; the content of the SnO2 is not higher than the content of the Sb2O3; and

[0035] K is defined as (the molar percentage content of Bi2O3 + the molar percentage content of SnO2 + the molar percentage content of BN), and K is 1.6-4.5.

[0036] The inventor of the present application has found that, in the initial stage of high-temperature sintering of the resistor disc, the appropriate amount of SnO2 can lower the phase transition temperature of Bi2O3 in the composition, so that the liquid phase sintering of the resistor disc is advanced, the growth of ZnO grains and the migration of grain boundaries are promoted, and spinel phase Zn2SnO4 is gradually formed in the high-temperature sintering process, which plays a pinning effect, avoids excessive growth of the grains, and maintains uniformity.

[0037] The inventor of the present application has also found that the appropriate amount of BN as a sintering aid can absorb the oxygen released by SnO2, MnO2 and Sb2O3, etc. in the high-temperature sintering process to generate B2O3 (as shown in formula (1)), further promote the liquid phase sintering, and supplement the evaporation of liquid phase Bi2O3, etc. in the high-temperature sintering process, thereby reducing the existence of internal pores of the resistor disc. And the active nitrogen atoms released by BN in the high-temperature sintering process dissolve and distribute in the grain boundaries and surface layers of ZnO grains, replace oxygen to form acceptor defects, improve the grain boundary barrier, and benefit the stability of the resistor disc.

[0038]

[0039] Preferably, the silver glass powder contains Ag2O, bismuth borosilicate glass, and the content of Ag2O is 20-40wt%, and the content of bismuth borosilicate glass is 60-80wt%; and the average particle size of the silver glass powder is 1-3μm.

[0040] As described above, the second aspect of the present application provides a method for preparing a high-stability direct-current resistor disc, which is performed by using the composition described in the first aspect, and comprises:

[0041] (1) performing first grinding on each component in the composition to obtain product I;

[0042] (2) mixing the product I with a binder and then performing drying treatment to obtain product II; performing tabletting treatment on the product II to obtain product III;

[0043] (3) sequentially performing degassing pre-sintering, high-temperature sintering, insulation layer coating and heat treatment on the product III to obtain product IV;

[0044] (4) performing electrode coating on the product IV to obtain the high-current direct-current resistor disc.

[0045] According to a preferred embodiment, in step (1), the grinding is performed in a sand mill containing deionized water, which comprises:

[0046] (a) performing first grinding on ZnO to obtain mixture I; and

[0047] carrying out second grinding on component A to obtain mixture II; wherein the component A contains Bi2O3, Sb2O3, Co2O3, MnO2, Cr2O3, SiO2, NiO and SnO2;

[0048] (b) carrying out third grinding on the mixture I, the mixture II and component B to obtain product I; wherein the component B contains Al(NO3)3·H2O, silver glass powder and BN.

[0049] More preferably, in step (a), the conditions of the first grinding include: the diameter of the grinding ball is 0.3-2.0 μm, the rotating speed is 800-1000 rpm, the circulating flow is 10-30 L / min, and the circulating duration is 0.3-2.0 h.

[0050] Further preferably, in step (a), the conditions of the second grinding include: the diameter of the grinding ball is 0.5-2.0 μm, the rotating speed is 1000-1500 rpm, the circulating flow is 20-40 L / min, and the circulating duration is 1-2 h.

[0051] Preferably, in step (b), the conditions of the third grinding include: the diameter of the grinding ball is 0.1-1.0 μm, the rotating speed is 1500-2500 rpm, the circulating flow is 30-50 L / min, and the circulating duration is 0.5-3.0 h.

[0052] It should be noted that the kind and amount of the binder are not particularly limited in the present application, and those skilled in the art can select them according to the known technical means in the art. A preferred specific embodiment is exemplarily provided in the following of the present application, and those skilled in the art should not understand it as a limitation to the present application.

[0053] According to another preferred embodiment, the conditions of the drying treatment include: using a centrifugal spray granulator, and the inlet temperature is 220-240 ℃, the outlet temperature is 140-160 ℃, and the rotating speed of the centrifugal atomizing disc is 5000-10000 rpm.

[0054] Preferably, the conditions of the tabletting treatment include: the pressure P is 3-10 MPa, when the pressure reaches (2 / 3)P, the pressure is maintained for 10-30 s; and when the pressure reaches P, the pressure is maintained for 40-120 s.

[0055] It should be noted that the shape of the product III obtained after the tabletting treatment is not particularly limited in the present application, and those skilled in the art can select it according to the known technical means in the art. Exemplarily, the shape of the product III can be cylindrical and annular, and a preferred specific embodiment is provided in the following of the present application, and those skilled in the art should not understand it as a limitation to the present application.

[0056] It should be noted that the method of the said degumming pre-burning in step (3) is not particularly limited, and those skilled in the art can select according to the known technical means in the art. However, in order to obtain a higher stability of the resistance sheet, the present application provides a preferred embodiment: in step (3), the conditions of the said degumming pre-burning include: using four-stage temperature programming, and the starting temperature is 20-40℃, and the terminal temperature is 700-850℃.

[0057] More preferably, in step (3), the conditions of the said degumming pre-burning include:

[0058] First-stage temperature rise: the starting temperature is 20-40℃, and the temperature is raised to 300-350℃ at a temperature rise rate of 120-180℃ / h;

[0059] Second-stage temperature rise: the temperature is raised to 400-450℃ at a temperature rise rate of 40-80℃ / h, and the temperature is kept for 1-3h;

[0060] Third-stage temperature rise: the temperature is raised to 500-600℃ at a temperature rise rate of 30-60℃ / h, and the temperature is kept for 1-2h;

[0061] Fourth-stage temperature rise: the temperature is raised to the terminal temperature of 700-850℃ at a temperature rise rate of 100-120℃ / h, and the temperature is kept for 2-4h.

[0062] It should be noted that the method of the said high-temperature sintering in step (3) is also not particularly limited, and those skilled in the art can select according to the known technical means in the art. However, in order to obtain a higher stability of the resistance sheet, the present application provides another preferred embodiment: in step (3), the conditions of the said high-temperature sintering include: using two-stage temperature programming + two-stage temperature programming, and the starting temperature is 20-40℃, and the terminal temperature is 600-700℃.

[0063] Further preferably, the conditions of the said high-temperature sintering include:

[0064] First-stage temperature rise: the starting temperature is 20-40℃, and the temperature is raised to 900-950℃ at a temperature rise rate of 60-150℃ / h; the temperature is kept for 1-2h;

[0065] Second-stage temperature rise: the temperature is raised to 1000-1050℃ at a temperature rise rate of 30-90℃ / h, and the temperature is kept for 2-6h;

[0066] First-stage temperature drop: the temperature is dropped to 825-875℃ at a temperature drop rate of 60-120℃ / h;

[0067] Second-stage temperature drop: the temperature is dropped to the terminal temperature of 600-700℃ at a temperature drop rate of 20-60℃ / h.

[0068] Preferably, in step (3), the raw material of the insulation layer is selected from at least one of inorganic glass glaze and organic insulation glaze, and the electrode is selected from at least one of aluminum electrode and silver electrode.

[0069] Preferably, the coating condition of the insulation layer comprises: spraying pressure of 0.5-0.9 MPa, flow rate of 0.5-2.5 m 3 / min, and spraying thickness of 100-500 μm.

[0070] Preferably, the coating condition of the electrode comprises: spraying pressure of 0.7-0.8 MPa, flow rate of >1 m 3 / min, and spraying thickness of 80-150 μm.

[0071] Preferably, in step (3), the heat treatment condition comprises: being carried out in a saggar, and initial temperature of 20-40 ℃, temperature rising at a rate of 90-180 ℃ / h to 500-550 ℃ and holding for 2-4 h, and then temperature falling at a rate of 10-50 ℃ / h to 200-220 ℃. The inventors of the present application find that the resistance piece obtained under the preferred condition has better stability.

[0072] Particularly preferably, the saggar is a stainless steel cuboid, and one side of the cuboid is in a hollow grid shape and has at least one layer of stainless steel net inside. The inventors of the present application find that, compared with a corundum saggar, the stainless steel saggar has better heat conduction effect and is heated more uniformly; and the design of one side in a hollow grid shape can accelerate the circulation of atmosphere, ensure the transportation of oxygen required for heat treatment, promote the elimination of metastable defects in the grain boundary, improve the stability of the grain boundary, and thus improve the stability of the resistance piece.

[0073] As described above, the third aspect of the present application provides a high-stability direct-current resistance piece prepared by the method described in the aforementioned first aspect.

[0074] As described above, the fourth aspect of the present application provides the use of the high-stability direct-current resistance piece described in the aforementioned third aspect in lightning protection equipment.

[0075] The present application will be described in detail below through examples.

[0076] In the following examples, the raw materials used are commercially available unless otherwise specified.

[0077] In the following examples, the room temperature means 25±2 ℃ unless otherwise specified.

[0078] Raw materials:

[0079] Silver glass powder: containing Ag2O, bismuth borosilicate glass, and the content of Ag2O is 30wt%, the content of bismuth borosilicate glass is 70wt%; and the average particle size of silver glass powder is 2μm.

[0080] Apparatus:

[0081] Sand mill: Model NM21L, NuoJian (Shanghai) Machinery Instrument Co., Ltd.

[0082] Centrifugal spray granulator: Model SFL-12, Changzhou Yikang Pharmaceutical and Chemical Equipment Co., Ltd.

[0083] Hydraulic press: Model FS79ZK-100G, Nantong Fushi Hydraulic Press Co., Ltd.

[0084] Example 1

[0085] The components and their contents in the composition applied in this example are as follows:

[0086] 92.255mol% of ZnO, 1.23mol% of Bi2O3, 1.17mol% of Sb2O3, 0.82mol% of Co2O3, 0.78mol% of MnO2, 0.35mol% of Cr2O3, 0.75mol% of SiO2, 0.96mol% of NiO, 0.40mol% of SnO2, 1.13mol% of BN, 0.005mol% of Al(NO3)3·H2O, 0.15mol% of silver glass powder;

[0087] The above composition is used to prepare a resistor disc P1 by the following method:

[0088] (1) In a sand mill containing deionized water,

[0089] (a) ZnO is first ground to obtain mixture I;

[0090] The first grinding conditions are: zirconium oxide grinding ball diameter is 1.5μm, rotation speed is 900rpm, circulation flow rate is 20L / min, and circulation duration is 1h;

[0091] Bi2O3, Sb2O3, Co2O3, MnO2, Cr2O3, SiO2, NiO and SnO2 in component A are second ground to obtain mixture II;

[0092] The second grinding conditions are: zirconium oxide grinding ball diameter is 1.0μm, rotation speed is 1200rpm, circulation flow rate is 30L / min, and circulation duration is 2h;

[0093] (b) performing third grinding on the mixture I, the mixture II and Al(NO3)3·H2O, silver glass powder and BN in component B, to obtain product I;

[0094] The third grinding is performed under the conditions of zirconium oxide grinding balls with a diameter of 0.5 μm, a rotation speed of 2000 rpm, a circulation flow rate of 40 L / min and a circulation duration of 2.5 h.

[0095] (2) performing drying treatment on the product I after mixing with a binder, to obtain product II; and performing tabletting treatment on the product II, to obtain product III;

[0096] The drying treatment is performed by using a centrifugal spray granulator, and the inlet temperature is 230 ℃, the outlet temperature is 150 ℃, and the rotation speed of the centrifugal atomizing disc is 8000 rpm.

[0097] The tabletting treatment is performed in a hydraulic press, and the pressure P is 5.7 MPa, the pressure is maintained for 20 s when the pressure reaches (2 / 3)P, and the pressure is maintained for 60 s when the pressure reaches P.

[0098] The binder is polyvinyl alcohol, and the weight ratio of the product I to the binder is 1:0.18.

[0099] (3) sequentially performing glue removal pre-burning, high-temperature sintering, insulation layer coating and heat treatment on the product III, to obtain product IV;

[0100] The glue removal pre-burning is performed under the conditions of:

[0101] First-stage temperature rising: the initial temperature is room temperature, and the temperature is raised to 350 ℃ at a temperature rising rate of 150 ℃ / h;

[0102] Second-stage temperature rising: the temperature is raised to 420 ℃ at a temperature rising rate of 60 ℃ / h, and the temperature is maintained for 2 h;

[0103] Third-stage temperature rising: the temperature is raised to 550 ℃ at a temperature rising rate of 50 ℃ / h, and the temperature is maintained for 1.5 h;

[0104] Fourth-stage temperature rising: the temperature is raised to the final temperature of 800 ℃ at a temperature rising rate of 100 ℃ / h, and the temperature is maintained for 3 h;

[0105] The high-temperature sintering is performed under the conditions of:

[0106] First-stage temperature rising: the initial temperature is room temperature, and the temperature is raised to 950 ℃ at a temperature rising rate of 90 ℃ / h; the temperature is maintained for 1 h;

[0107] Second-stage temperature rising: the temperature is raised to 1030 ℃ at a temperature rising rate of 60 ℃ / h, and the temperature is maintained for 4 h;

[0108] First stage of cooling: Cool down to 850℃ at a rate of 60℃ / h;

[0109] The second stage of cooling: cooling at a rate of 40℃ / h until the final temperature of 700℃ is reached;

[0110] The conditions for coating the insulating layer are: spraying pressure of 0.6 MPa and flow rate of 1.2 m³ / min. 3 / min, spraying thickness of 300μm, coating surface is the side of the cylinder;

[0111] The raw material for the insulating layer is inorganic glass glaze;

[0112] The conditions for the heat treatment are: [The conditions are described in the original text, which are not directly related to the heat treatment conditions.] Figure 4 The experiment was carried out in the sagger shown, with the initial temperature at room temperature. The temperature was increased to 525℃ at a heating rate of 120℃ / h and held for 3 hours, and then decreased to 200℃ at a cooling rate of 15℃ / h.

[0113] (4) The product IV is coated with electrodes to obtain a resistor P1 with a diameter of 75 mm;

[0114] The electrode coating conditions are: spraying pressure of 0.75 MPa and flow rate of 1.5 m³ / min. 3 / min, spraying thickness of 100μm, coating surface is the upper and lower surfaces of the cylinder;

[0115] The electrode is an aluminum electrode.

[0116] Figure 1 This is a SEM image of the microstructure of the resistor in Embodiment 1 of the present invention. (The image is obtained through...) Figure 1 It can be seen that the ZnO particles in the resistor chip provided by the present invention are small and concentrated, and various secondary phases such as spinel phase at the grain boundaries are evenly distributed with few local concentrations and few internal pores.

[0117] Figure 2 This is a schematic diagram of the bismuth oxide crystal form at the grain boundaries of the product microstructure before heat treatment provided by the present invention. Figure 3 This is a schematic diagram of the bismuth oxide crystal form at the grain boundaries in the microstructure of the product after heat treatment according to the present invention. The heat treatment method provided in this invention can transform the original α-type Bi₂O₃ phase and β-type Bi₂O₃ phase at the grain boundaries into more β-type Bi₂O₃ phase and γ-type Bi₂O₃ phase, such as... Figure 2 and Figure 3 As shown, it can eliminate more metastable components, improve the grain boundary stability of the resistor, obtain a more stable grain boundary structure, and make the resistor perform better and more stable under current impact or DC aging on a macroscopic scale.

[0118] Figure 4is a front view of a preferred saggar provided by the present application. In Figure 4 In the present application, the resistor disc precursor refers to the product obtained after the insulating layer is coated.

[0119] Figure 5 is a schematic view of a preferred saggar provided by the present application. Figure 5 The hollow grid side surface in the present application is arranged opposite to the stainless steel cover surface in the saggar in the present application. Figure 4

[0120] Example 2

[0121] The present example is performed by using the same composition and similar method as in Example 1, except that:

[0122] In step (3), the fourth section of the temperature rising in the degassing pre-burning is adjusted to be raised to the final temperature of 860℃ at a temperature rising rate of 100℃ / h, and kept for 1h, and the rest is the same as in Example 1, thereby preparing the resistor disc P2 with a diameter of 75mm.

[0123] Example 3

[0124] The present example is performed by using the same composition and similar method as in Example 1, except that:

[0125] In step (3), the second section of the temperature rising in the high-temperature sintering is adjusted to be raised to 1060℃ at a temperature rising rate of 60℃ / h, and kept for 3h, and the rest is the same as in Example 1, thereby preparing the resistor disc P3 with a diameter of 75mm.

[0126] Example 4

[0127] The present example is performed by using the same composition and similar method as in Example 1, except that:

[0128] In step (3), the heat treatment is performed in the saggar shown in Figure 4 , and the starting temperature is room temperature, and the temperature is raised to 555℃ at a temperature rising rate of 120℃ / h and kept for 2.5h, and then the temperature is lowered to 200℃ at a temperature lowering rate of 15℃ / h, and the rest is the same as in Example 1, thereby preparing the resistor disc P4 with a diameter of 75mm.

[0129] Comparative Example 1

[0130] The present comparative example is performed by using the same composition and similar method as in Example 1, except that:

[0131] The content of SnO2 in the composition is adjusted to be 1.75mol%, and the content of ZnO is adjusted to be 90.905mol%, and the rest is the same as in Example 1,

[0132] ​wherein K = 4.11, and a resistance disc DP1 with a diameter of 75 mm is prepared.

[0133] Comparative Example 2

[0134] The comparative example is carried out using a similar composition and the same method as in Example 1, except that:

[0135] The content of BN in the composition is adjusted to 2.13 mol%, the content of ZnO is adjusted to 91.255 mol%, and the rest is the same as in Example 1,

[0136] wherein K = 5.01, and a resistance disc DP2 with a diameter of 75 mm is prepared.

[0137] Comparative Example 3

[0138] The comparative example is carried out using a similar composition and the same method as in Example 1, except that:

[0139] The content of Bi2O3 in the composition is adjusted to 0.53 mol%, the content of ZnO is adjusted to 92.955 mol%, and the rest is the same as in Example 1, and a resistance disc DP3 with a diameter of 75 mm is prepared.

[0140] Comparative Example 4

[0141] The comparative example is carried out using a similar composition and the same method as in Example 1, except that:

[0142] The content of SiO2 in the composition is adjusted to 0.25 mol%, the content of ZnO is adjusted to 92.755 mol%, and the rest is the same as in Example 1, and a resistance disc DP4 with a diameter of 75 mm is prepared.

[0143] Test Example

[0144] The resistance discs prepared in the examples and comparative examples are subjected to the following performance tests, and the specific results are shown in Table 1:

[0145] The voltage gradient, leakage current, residual voltage ratio, through-flow capacity under 4 / 10 μs current impulse, and aging coefficient are tested according to the corresponding methods in GB / T 11032-2020 AC Gapless Metal Oxide Surge Arrester.

[0146] Table 1

[0147]

[0148] As can be seen from the results of Table 1, the resistance chip prepared by using the composition and preparation method provided by the application has the advantages of high voltage gradient, small leakage current, low residual voltage ratio, good basic electrical performance, etc., is beneficial to long-term stable operation; and has high current carrying capacity under 4 / 10 μs current impact, can withstand high impact current amplitude, can effectively lead lightning current or impact current into the ground, and plays a DC line protection role. In addition, after the resistance chip provided by the application is subjected to aging test under the DC acceleration condition of 115℃ / 0.95 charge rate / 1000h, the aging coefficient is small, the anti-aging performance is good, and the resistance chip can be stably and long-term operated under the action of continuous DC electric field.

[0149] The above results show that the composition and preparation method provided by the application can improve the uniformity of the microstructure of the resistance chip, reduce the existence of internal pores, can make the electrical performance of the resistance chip change little under current impact and the action of continuous DC electric field, and the performance is stable.

[0150] The above describes the preferred embodiments of the application, but the application is not limited thereto. Within the technical concept of the application, various simple modifications can be made to the technical solutions of the application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as the disclosed content of the application, and all belong to the protection scope of the application.

Claims

1. A method for preparing a high-stability DC resistive sheet, characterized in that, This method utilizes a composition for preparing highly stable DC resistive sheets, comprising: (1) The components in the composition are subjected to a first grinding process to obtain product I; The composition contains the following components: ZnO, Bi2O3, Sb2O3, Co2O3, MnO2, Cr2O3, SiO2, NiO, SnO2, BN, Al(NO3)3·H2O, and silver glass powder; Based on the total molar amount of the composition, the content of ZnO is 87-95 mol%, the content of Bi2O3 is 0.7-2.5 mol%, the content of Sb2O3 is 0.2-2.5 mol%, the content of Co2O3 is 0.5-2 mol%, the content of MnO2 is 0.2-1.7 mol%, the content of Cr2O3 is 0.3-0.8 mol%, the content of SiO2 is 0.3-1 mol%, the content of NiO is 0.5-1.8 mol%, the content of SnO2 is 0.1-0.8 mol%, the content of BN is 0.3-2 mol%, the content of Al(NO3)3·H2O is 0.003-0.02 mol%, and the content of silver glass powder is 0.005-0.20 mol%. Furthermore, the content of SnO2 is not higher than the content of Bi2O3; the content of SnO2 is not higher than the content of Sb2O3; and Define K = (molar percentage of Bi2O3 + molar percentage of SnO2 + molar percentage of BN), and K is 1.6-4.5; The silver glass powder contains Ag2O and bismuth borosilicate glass, with Ag2O content of 20-40 wt% and bismuth borosilicate glass content of 60-80 wt%; and the average particle size of the silver glass powder is 1-3 μm. (2) The product I is mixed with the adhesive and then dried to obtain product II; the product II is compressed into tablets to obtain product III; (3) The product III is subjected to debinding pre-firing, high-temperature sintering, insulating layer coating and heat treatment in sequence to obtain product IV; the heat treatment conditions include: it is carried out in a sagger, and the initial temperature is 20-40℃, the temperature is raised to 500-550℃ at a heating rate of 90-180℃ / h and held for 2-4h, and then the temperature is lowered to 200-220℃ at a cooling rate of 10-50℃ / h. (4) The product IV is coated with electrodes to obtain a high-stability DC resistor.

2. The method according to claim 1, wherein, In step (1), the grinding is carried out in a sand mill containing deionized water, including: (a) ZnO is first ground to obtain mixture I; and Component A is subjected to a second grinding to obtain mixture II; wherein component A contains Bi2O3, Sb2O3, Co2O3, MnO2, Cr2O3, SiO2, NiO and SnO2; (b) The mixture I, the mixture II and component B are subjected to a third grinding to obtain product I; wherein component B contains Al(NO3)3·H2O, silver glass powder and BN.

3. The method according to claim 1 or 2, wherein, In step (3), the conditions for the preheating of the glue include: using a four-stage programmable temperature rise, with an initial temperature of 20-40℃ and an ending temperature of 700-850℃.

4. The method according to claim 1 or 2, wherein, In step (3), the conditions for high-temperature sintering include: using a two-stage programmed heating + a two-stage programmed cooling, with an initial temperature of 20-40℃ and an end temperature of 600-700℃.

5. The method according to claim 1, wherein, The sagger is a stainless steel cuboid, with one side of the cuboid having a perforated mesh shape and at least one layer of stainless steel mesh inside.

6. A high-stability DC resistor sheet prepared by the method according to any one of claims 1-5.

7. The application of the high-stability DC resistor sheet as described in claim 6 in lightning protection equipment.

Images