CN114141458B - High-stability high-power ceramic resistor and preparation method thereof - Google Patents

High-stability high-power ceramic resistor and preparation method thereof Download PDF

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CN114141458B
CN114141458B CN202111444949.7A CN202111444949A CN114141458B CN 114141458 B CN114141458 B CN 114141458B CN 202111444949 A CN202111444949 A CN 202111444949A CN 114141458 B CN114141458 B CN 114141458B
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resistor
protective layer
matrix
sintering
preparing
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CN114141458A (en
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尧中华
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Abstract

The invention relates to a high-stability high-power ceramic resistor and a preparation method thereof. The high-stability high-power ceramic resistor comprises: a resistor matrix and a protective layer coated on the outer periphery of the resistor matrix; the raw materials for preparing the resistor matrix comprise: acetylene black, bentonite, wollastonite and/or alumina, resistance modifier; the raw materials for preparing the protective layer comprise: water glass and nano alumina. According to the invention, the protective layer formed by taking water glass and nano alumina as raw materials is coated on the peripheral surface of the resistor substrate, so that the bearable temperature and heat dissipation performance of the resistor can be improved, the resistor is isolated from oxygen at high temperature, and the resistor is prevented from cracking and oxidation failure at high temperature; by adding the resistance modifier into the resistor matrix, the problem of instability of the high-power resistor at high temperature is solved, the stability of the resistor caused by severe heat at high temperature or under high energy impact is remarkably improved, and the use environment of the resistor is widened.

Description

High-stability high-power ceramic resistor and preparation method thereof
Technical Field
The invention relates to the technical field of inorganic nonmetallic materials, in particular to a high-stability high-power ceramic resistor and a preparation method thereof.
Background
Advanced electronic devices and systems often require resistors to have good stability and reliability under high voltage, high power and high current operating conditions. For technical reasons, today's high power resistors mainly have two types: wound and film. The winding resistor has large volume, low resistance, large distributed capacitance and inductance, and is difficult to pass because the winding resistor plays a role of a choke coil for current. The film type plane power resistor has high negative resistance coefficient, so that the temperature stability of the resistor is poor, and the stability is seriously influenced. The solid ceramic resistor can bear high energy and high pulse impact due to the conduction of the whole body, has no inductance and good thermal stability, has incomparable superiority of the two resistors on high-voltage, high-power and high-frequency circuits, and is very suitable for occasions such as capacitor charging and discharging. The high-power ceramic resistor used in China at present mainly depends on import, but the domestic high-power ceramic resistor has the technical problems of poor stability, easiness in cracking or high-temperature failure and the like under the conditions of high voltage and high current pulse and the like, and has no breakthrough. The main reasons for these phenomena are that the unreasonable design of the resistive material results in a high temperature coefficient of resistance of the material and carbon oxidation at high temperature results in failure of the resistor.
Disclosure of Invention
In view of the foregoing, it is necessary to provide a high-stability high-power ceramic resistor and a preparation method thereof, so as to solve the technical problems of poor stability, easy cracking or high-temperature failure of the high-power ceramic resistor in the prior art.
A first aspect of the present invention provides a high-stability high-power ceramic resistor comprising: a resistor matrix and a protective layer coated on the outer periphery of the resistor matrix;
the raw materials for preparing the resistor matrix comprise: acetylene black, bentonite, wollastonite and/or alumina, resistance modifier; the resistance modifier consists of modified barium titanate and NiMn 2 O 4 Mixing;
the raw materials for preparing the protective layer comprise: water glass and nano alumina.
The second aspect of the invention provides a method for preparing a high-stability high-power ceramic resistor, which comprises the following steps:
preparing a resistor matrix: mixing acetylene black, bentonite, wollastonite and/or alumina, a resistance modifier, a binder and water, ball milling, granulating, press forming and sintering for one time to obtain a resistance matrix;
and (3) coating a protective layer: mixing water glass, nano alumina and water, ball milling, coating on the outer periphery of the resistor matrix, and performing secondary sintering to form a protective layer coated on the resistor matrix on the outer periphery of the resistor matrix.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, the protective layer formed by taking water glass and nano alumina as raw materials is coated on the peripheral surface of the resistor substrate, so that the bearable temperature and heat dissipation performance of the resistor can be improved, the resistor is isolated from oxygen at high temperature, and the resistor is prevented from cracking and oxidation failure at high temperature; by adding the resistance modifier into the resistor matrix, the problem of instability of the high-power resistor at high temperature is solved, the stability of the resistor caused by severe heat at high temperature or under high energy impact is remarkably improved, and the use environment of the resistor is widened.
Drawings
FIG. 1 is a schematic diagram of a high-power ceramic resistor with high stability according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Referring to fig. 1, a first aspect of the present invention provides a high-stability high-power ceramic resistor, comprising: the resistor comprises a resistor matrix 1, a protective layer 2, two electrode caps 3 and a lead-out wire 4; the protective layer 2 is coated on the outer peripheral surface of the resistor matrix 1, the two electrode caps 3 are respectively sleeved on the end surfaces of the two ends of the resistor matrix 1 and are in contact with the protective layer 2, and the outsides of the two electrode caps 3 are respectively connected with the lead-out wires 4.
The invention can improve the bearable temperature and heat dissipation property of the resistor by arranging the protective layer 2, so that the resistor can isolate oxygen at high temperature and prevent the oxidation failure of the resistor at high temperature.
In the present invention, the raw materials for preparing the resistor substrate 1 include: acetylene black, bentonite, wollastonite and/or alumina, and a resistance modifier.
In the invention, the ceramic matrix is formed by bentonite and at least one of wollastonite and alumina at high temperature, so that the mechanical strength of the resistor can be improved. Preferably, the mass ratio of bentonite to wollastonite to alumina is 1: (0.15-0.65). Within this mass ratio range, the resistor can be made to have a higher strength and a lower sintering temperature.
In some preferred embodiments of the present invention, the acetylene black is prepared by an incomplete combustion method, and has a surface with more oxygen groups and a conductivity slightly inferior to other carbon materials, so that the electrical resistance with a wider range can be precisely adjusted by changing the formulation. Further, the electrical resistivity of acetylene black is 2 to 6Ω·m.
In some preferred embodiments of the present invention, the resistance modifier is formed from modified barium titanate and spinel structured nickel-manganese-oxygen (NiMn 2 O 4 ) The compound is mixed. According to the invention, the temperature drift characteristics of the resistor are corrected by adopting the materials with positive and negative temperature coefficients, so that the problem of instability of the high-power resistor at high temperature is solved, the stability of the resistor at high temperature or under high energy impact is remarkably improved, and the use environment of the resistor is widened.
Modified barium titanate and NiMn 2 O 4 All are prepared by adopting a method common in the field of materials. For example, modified barium titanate may be formed by sintering oxides and barium titanate at high temperatures; can pass MnO and Ni 2 O 3 Is sintered at high temperature to obtain NiMn 2 O 4 。
In some embodiments of the invention, the modified barium titanate is obtained by sintering barium titanate, yttrium oxide, and manganese oxide at a high temperature, wherein the molar ratio of yttrium oxide to manganese oxide is 1: (5-10), further 1:8; the sum of the added amounts of yttrium oxide and manganese oxide accounts for 0.1% -1% of barium titanate, and is further 0.6%; the high-temperature sintering temperature is 1200-1400 ℃, further 1300 ℃, and the time is 1-3 h, further 2h.
In some more preferred embodiments of the present invention, the resistance-modifying agent consists of the following raw materials in mass percent: 20-40% of modified barium titanate and NiMn 2 O 4 60% -80% of material.
In some preferred embodiments of the present invention, the acetylene black has a particle size of 2000 to 3000 mesh, and the bentonite, wollastonite, alumina, and resistance-modifying agent have a particle size of 300 mesh or less.
In some preferred embodiments of the present invention, the raw materials for preparing the resistive matrix 1 comprise, in weight percent: 5 to 25 percent of acetylene black, 40 to 60 percent of bentonite, 10 to 25 percent of wollastonite and/or alumina and 5 to 15 percent of resistance modifier.
In the invention, the raw materials for preparing the resistor matrix 1 also comprise; binder and water. Further, the addition amount of the binder accounts for 1-5% of the total mass of the acetylene black, bentonite, wollastonite and/or aluminum oxide, and further 2.5%; the addition amount of water is 1.5-2 times of the total mass of the acetylene black, bentonite, wollastonite and/or alumina and the resistance modifier.
The specific kind of the binder to be used in the present invention is not limited, and may be selected by those skilled in the art according to actual circumstances. In some embodiments of the invention, the binder selected is polyvinyl alcohol (PVA).
The preparation of the resistor matrix adopts a method common in the ceramic field. For example, it may be: adding binder into the mixture of acetylene black, bentonite, wollastonite and/or alumina and resistance modifier, ball milling with water as medium, granulating by spray drying, and press molding and sintering to obtain the resistor matrix.
In the present invention, the raw materials for preparing the protective layer 2 include: water glass and nano alumina. According to the invention, aluminum oxide with excellent heat conduction and insulation properties is adopted as a coating, and the cohesiveness of water glass is utilized, and atomization spraying is adopted to obtain a protective layer, so that the bearable temperature of the resistor can reach more than 450 ℃; meanwhile, the nano aluminum oxide is adopted in the protective layer, so that the heat conductivity is remarkably improved, the gathered heat can be rapidly dissipated outwards, and cracking caused by sharp heat gathering is prevented.
In some preferred embodiments of the present invention, the raw materials for preparing the protective layer 2 include, in weight percent: 50-60% of water glass and 40-50% of nano alumina. According to the invention, the content of the water glass and the nano alumina is controlled within the range, so that the sintering temperature of the protective layer can be reduced, and the influence on the performance of the resistor due to the overhigh sintering temperature of the protective layer is avoided; meanwhile, the protective layer has better heat conduction performance.
In the present invention, the raw materials of the protective layer 2 further include: and (3) water. Further, the addition amount of water is 2-5 times, and further 3 times of the total mass of the water glass and the nano alumina.
In some embodiments of the invention, the concentration of the water glass is 30% -35%, further 34%, and the modulus is 3-3.5, further 3.3; the grain diameter of the nanometer alumina is 20-50 nm.
In the present invention, the thickness of the protective layer is 10 to 200 micrometers. If the thickness of the protective layer is too high, the heat dissipation performance is not improved, and the protective layer is easy to fall off from the resistor matrix; if the thickness of the protective layer is too low, the resistor has poor high temperature stability.
In some preferred embodiments of the invention, the protective layer has a thickness of 30 to 60 microns.
In the invention, the ceramic resistor further comprises metal electrodes (not shown in the figure), wherein the metal electrodes are arranged on the end surfaces of the two ends of the resistor substrate coated with the protective layer and are contacted with the electrode caps through solder paste. Further, the metal electrode is made of at least one of copper and aluminum.
The specific materials and arrangement of the electrode cap 3 and the lead-out wire 4 in the present invention are not limited, and those skilled in the art can select according to actual situations. For example, the electrode cap 3 may be a chromium-zirconium-copper or copper electrode cap commonly used in the art, and the welding method is to coat solder paste after forming a metal electrode on the end face of the resistor substrate 1, cover the electrode cap, and weld by reflow soldering technology; the lead-out wire 4 may be connected to the electrode cap 3 by soldering using copper or aluminum wire or the like commonly used in the art.
The second aspect of the invention provides a preparation method of a high-stability high-power ceramic resistor, which comprises the following steps:
s1, preparing a resistor matrix: mixing acetylene black, bentonite, wollastonite and/or alumina, a resistance modifier, a binder and water, ball milling, granulating, press forming and sintering for one time to obtain a resistance matrix;
s2, coating a protective layer: mixing water glass, nano alumina and water, ball milling, coating on the outer periphery of the resistor matrix, and performing secondary sintering to form a protective layer coated on the resistor matrix on the outer periphery of the resistor matrix.
In the present invention, the granulation process is carried out by means of spray drying.
In the present invention, the molding pressure is 150 to 200MPa, more preferably 175 to 185MPa, still more preferably 180MPa.
In the invention, the temperature of primary sintering is 940-1300 ℃, and further 950-1250 ℃; the time of one sintering is 100-150 min, more 110-130 min, still more 120min.
In the invention, slurry formed by mixing and ball milling water glass, nano alumina and water is coated on the surface of a resistor matrix in an atomizing spraying mode.
In the invention, the temperature of secondary sintering is 860-900 ℃, further 870-890 ℃, and further 880 ℃; the secondary sintering time is 10-30 min, more 15-25 min and still more 20min.
In the invention, the primary sintering and the secondary sintering are both carried out under inert atmosphere. In some embodiments of the invention, the inert atmosphere is nitrogen or argon.
In the invention, the preparation method of the high-stability high-power ceramic resistor further comprises the following steps:
s3, spraying a metal electrode: spraying metal electrodes on the end surfaces of the two ends of the resistor matrix coated with the protective layer; further, the sprayed thickness of the metal electrode is 10-50 μm.
S4, welding an electrode cap: coating solder paste on the end surfaces of two ends of a resistor matrix sprayed with a metal electrode, covering an electrode cap, and welding the electrode cap on two ends of the resistor matrix through reflow soldering;
s5, welding lead-out wires: and welding lead-out wires on the two electrode caps to obtain a resistor finished product.
In the following examples and comparative examples of the present invention, for avoiding redundancy, some raw materials are summarized as follows:
acetylene black: the adopted model is 75% compression; the manufacturer: tianjin Zhengning New Material technologies Co., ltd;
water glass: concentration is 34% and modulus is 3.3; the suppliers: shandong Usoxhlet chemical engineering Co., ltd;
the preparation process of the modified barium titanate comprises the following steps: uniformly mixing barium carbonate and titanium dioxide, and sintering at 1250 ℃ for 2 hours to prepare barium titanate powder; uniformly mixing barium titanate, yttrium oxide and manganese oxide, and sintering at a high temperature of 1300 ℃ for 2 hours to obtain modified barium titanate; wherein, the mol ratio of yttrium oxide to manganese oxide is 1:8, and the sum of the addition amount of the yttrium oxide and the manganese oxide accounts for 0.6 percent of barium titanate.
Example 1
The preparation method of the high-stability high-power ceramic resistor provided by the embodiment comprises the following steps:
(1) Preparing a resistor matrix: to 10kg of a resistor powder (0.5 kg of acetylene black, 5.8kg of bentonite, 2.5kg of wollastonite, 0.48kg of modified barium titanate and 0.72kg of NiMn) 2 O 4 ) Adding 0.25kg of polyvinyl alcohol and 15kg of deionized water, putting into a ball milling tank, and uniformly mixing; granulating by spray drying technology; pressing the obtained granulated powder under 180MPa by a press to obtain a cylinder with the diameter of 21mm and the height of 30mm, and sintering under the protection of argon, wherein the sintering temperature is 980 ℃ and the time is 2 hours, so as to obtain a high-power ceramic resistor matrix 1;
(2) And (3) coating a protective layer: 600g of water glass and 400g of nano alumina (20 nm) are weighed, ball milling is carried out by taking 3kg of water as a medium, and slurry is prepared for standby; spraying the powder on the outer peripheral surface of the resistor matrix 1 by atomization, and rapidly sintering the powder for 20 minutes at 880 ℃ under the protection of argon gas, wherein the thickness is 30 micrometers;
(3) Spraying a metal electrode: adopting plasma spraying equipment to spray copper electrodes on the end surfaces of the two ends of the resistor matrix coated with the protective layer; wherein the spraying thickness is 20 mu m;
(4) Welding an electrode cap: coating solder paste on the end surfaces of two ends of a resistor matrix sprayed with a metal electrode, covering an electrode cap 3, and welding in a reflow welding machine;
(5) Welding lead-out wires: and welding the lead-out wire 4 to obtain a resistor finished product.
The embodiment can prepare the ceramic resistor with the resistance value of 57.3+/-10 percent omega, can resist 45.2kV impact voltage, can only absorb 320J in a single way, can bear the temperature range of-55-450 ℃, and has the temperature resistance change rate of less than 0.1 percent per DEG C.
Example 2
The preparation method of the high-stability high-power ceramic resistor provided by the embodiment comprises the following steps:
(1) Preparing a resistor matrix: to 10kg of a resistor powder (2 kg of acetylene black, 5.6kg of bentonite, 1kg of wollastonite, 0.43kg of modified barium titanate and 0.97kg of NiMn) 2 O 4 ) Adding 0.25kg of polyvinyl alcohol and 20kg of deionized water, putting into a ball milling tank, and uniformly mixing; granulating by spray drying technology; pressing the obtained granulated powder under 180MPa by a press to obtain a cylinder with the diameter of 21mm and the height of 30mm, and sintering under the protection of argon, wherein the sintering temperature is 1000 ℃ and the sintering time is 2 hours, so as to obtain a high-power ceramic resistor matrix 1;
(2) And (3) coating a protective layer: 600g of water glass and 400g of nano alumina (20 nm) are weighed, ball milling is carried out by taking 3kg of water as a medium, and slurry is prepared for standby; spraying the powder on the outer peripheral surface of the resistor matrix 1 by atomization, and rapidly sintering the powder for 20 minutes at 880 ℃ under the protection of argon gas with the thickness of 40 micrometers;
(3) Spraying a metal electrode: adopting plasma spraying equipment to spray copper electrodes on the end surfaces of the two ends of the resistor matrix coated with the protective layer; wherein the spraying thickness is 10 mu m;
(4) Welding an electrode cap: coating solder paste on the end surfaces of two ends of a resistor matrix sprayed with a metal electrode, covering an electrode cap 3, and welding in a reflow welding machine;
(5) Welding lead-out wires: and welding the lead-out wire 4 to obtain a resistor finished product.
The embodiment can prepare the ceramic resistor with the resistance value of 20.1+/-10 percent omega, can resist 34.3kV impact voltage, can only absorb 450J in a single way, can bear the temperature range of-55-450 ℃, and has the resistance temperature change rate of less than 0.1 percent per DEG C.
Example 3
The preparation method of the high-stability high-power ceramic resistor provided by the embodiment comprises the following steps:
(1) Preparing a resistor matrix: to 10kg of a resistor powder (2.5 kg of acetylene black, 5kg of bentonite, 2kg of wollastonite, 0.1kg of modified barium titanate and 0.4kg of NiMn) 2 O 4 ) Adding 0.25kg of polyvinyl alcohol and 15kg of deionized water, putting into a ball milling tank, and uniformly mixing; granulating by spray drying technology; pressing the obtained granulated powder under 180MPa by a press to obtain a cylinder with the diameter of 21mm and the height of 30mm, and sintering under the protection of argon, wherein the sintering temperature is 1080 ℃ and the sintering time is 2 hours, so as to obtain a high-power ceramic resistor matrix 1;
(2) And (3) coating a protective layer: 550g of water glass and 450g of nano alumina (20 nm) are weighed, ball milling is carried out by taking 3kg of water as a medium, and slurry is prepared for standby; spraying the powder on the outer peripheral surface of the resistor matrix 1 by atomization, and rapidly sintering the powder for 20 minutes at 880 ℃ under the protection of argon gas, wherein the thickness is 30 micrometers;
(3) Spraying a metal electrode: adopting plasma spraying equipment to spray copper electrodes on the end surfaces of the two ends of the resistor matrix coated with the protective layer; wherein the spraying thickness is 30 μm;
(4) Welding an electrode cap: coating solder paste on the end surfaces of two ends of a resistor matrix sprayed with a metal electrode, covering an electrode cap 3, and welding in a reflow welding machine;
(5) Welding lead-out wires: and welding the lead-out wire 4 to obtain a resistor finished product.
The embodiment can prepare the ceramic resistor with the resistance value of 0.7+/-10 percent omega, can resist 14.4kV impact voltage, can only absorb 620J in a single way, can bear the temperature range of-55-450 ℃, and has the resistance temperature change rate of less than 0.1 percent per DEG C.
Example 4
The preparation method of the high-stability high-power ceramic resistor provided by the embodiment comprises the following steps:
(1) Preparing a resistor matrix: to 10kg of a resistor powder (2.2 kg of acetylene black, 6kg of bentonite, 1.2kg of wollastonite, 0.18kg of modified barium titanate and 0.42kg of NiMn) 2 O 4 ) Adding 0.25kg of polyvinyl alcohol and 18kg of deionized water, and placingPutting the mixture into a ball milling tank, and uniformly mixing; granulating by spray drying technology; pressing the obtained granulated powder under 180MPa by a press to obtain a cylinder with the diameter of 21mm and the height of 30mm, and sintering under the protection of argon, wherein the sintering temperature is 950 ℃ and the sintering time is 2 hours, so as to obtain a high-power ceramic resistor matrix 1;
(2) And (3) coating a protective layer: weighing 500g of water glass and 500g of nano alumina (50 nm), and ball-milling with 3kg of water as a medium to prepare slurry for later use; spraying the powder on the outer peripheral surface of the resistor matrix 1 by atomization, and rapidly sintering the powder for 20 minutes at 880 ℃ under the protection of argon gas, wherein the thickness is 50 micrometers;
(3) Spraying a metal electrode: adopting plasma spraying equipment to spray copper electrodes on the end surfaces of the two ends of the resistor matrix coated with the protective layer; wherein the spraying thickness is 50 μm;
(4) Welding an electrode cap: coating solder paste on the end surfaces of two ends of a resistor matrix sprayed with a metal electrode, covering an electrode cap 3, and welding in a reflow welding machine;
(5) Welding lead-out wires: and welding the lead-out wire 4 to obtain a resistor finished product.
The embodiment can prepare the ceramic resistor with the resistance value of 6.8+/-10 percent omega, can resist 20.3kV impulse voltage, can only absorb 540J, can bear the temperature range of-55-450 ℃, and has the resistance temperature change rate of less than 0.1 percent per DEG C.
Example 5
The preparation method of the high-stability high-power ceramic resistor provided by the embodiment comprises the following steps:
(1) Preparing a resistor matrix: to 10kg of a resistor powder (2.1 kg of acetylene black, 4kg of bentonite, 2.4kg of wollastonite, 0.52kg of modified barium titanate and 0.98kg of NiMn) 2 O 4 ) Adding 0.25kg of polyvinyl alcohol and 17kg of deionized water, putting into a ball milling tank, and uniformly mixing; granulating by spray drying technology; pressing the obtained granulated powder under 180MPa by a press to obtain a cylinder with the diameter of 21mm and the height of 30mm, and sintering under the protection of argon, wherein the sintering temperature is 1200 ℃ and the sintering time is 2 hours, so as to obtain a high-power ceramic resistor matrix 1;
(2) And (3) coating a protective layer: 550g of water glass and 450g of nano alumina (50 nm) are weighed, ball milling is carried out by taking 3kg of water as a medium, and slurry is prepared for standby; spraying the powder on the outer peripheral surface of the resistor matrix 1 by atomization, and rapidly sintering the powder for 20 minutes at 880 ℃ under the protection of argon gas, wherein the thickness is 60 micrometers;
(3) Spraying a metal electrode: spraying an aluminum electrode on the end surfaces of the two ends of the resistor matrix coated with the protective layer by adopting plasma spraying equipment; wherein the spraying thickness is 40 μm;
(4) Welding an electrode cap: coating solder paste on the end surfaces of two ends of a resistor matrix sprayed with a metal electrode, covering an electrode cap 3, and welding in a reflow welding machine;
(5) Welding lead-out wires: and welding the lead-out wire 4 to obtain a resistor finished product.
The embodiment can prepare the ceramic resistor with the resistance value of 9.5+/-10 percent omega, can resist 28.2kV impact voltage, can only absorb 520J in a single way, can bear the temperature range of-55-450 ℃, and has the resistance temperature change rate of less than 0.1 percent per DEG C.
Example 6
Compared with example 1, the only difference is that: the wollastonite in the resistor matrix is replaced with alumina, and the resistor matrix is prepared as follows:
(1) Preparing a resistor matrix: to 10kg of a resistor powder (0.5 kg of acetylene black, 5.8kg of bentonite, 2.5kg of alumina, 0.48kg of modified barium titanate and 0.72kg of NiMn) 2 O 4 ) Adding 0.25kg of polyvinyl alcohol and 15kg of deionized water, putting into a ball milling tank, and uniformly mixing; granulating by spray drying technology; pressing the obtained granulated powder under 180MPa by a press to obtain a cylinder with the diameter of 21mm and the height of 30mm, and sintering under the protection of argon, wherein the sintering temperature is 1250 ℃ and the sintering time is 2 hours, so as to obtain a high-power ceramic resistor matrix 1;
the rest of the procedure is exactly the same as in example 1.
The embodiment can prepare the ceramic resistor with the resistance value of 63+/-10 percent omega, can resist 34kV impact voltage, can only absorb 300J in a single way, can bear the temperature range of-55 ℃ to 450 ℃, and has the resistance temperature change rate of less than 0.5 percent per DEG C.
Comparative example 1
Compared with example 1, the only difference is that: the protective layer is not covered.
The ceramic resistor with the resistance value of 54.6+/-10% omega can be prepared according to the comparative example, 30kV impact voltage can be resisted, only 270J can be absorbed, the temperature can be born within the range of-55 ℃ to 250 ℃, the resistance can be increased due to continuous increase of the temperature after impact, and the internal resistance temperature change rate is less than 0.1%/DEGC within the allowable temperature range.
Compared with the prior art, the invention has the beneficial effects that:
the ceramic composition in the ceramic resistor is uniform in distribution, high in density, high in energy density (more than 300J), free of inductance, more effective than a wire winding and a film resistor, controllable in process and high in yield, and resists high voltage and large current impact;
the resistor has the advantages of simple structure, small volume, low cost, convenient installation and controllable quality due to the conductive characteristic of the whole body;
the ceramic resistor is suitable for electronic circuits in the fields of high power, high pulse and the like, such as high voltage, high current and the like.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention.

Claims (7)

1. A high stability high power ceramic resistor comprising: a resistor matrix and a protective layer coated on the outer peripheral surface of the resistor matrix;
the raw materials for preparing the resistor matrix comprise: 5-25% of acetylene black, 40-60% of bentonite, 10-25% of wollastonite and/or alumina, and 5-15% of resistance modifier; the resistance modifier consists of 20-40% of modified barium titanate and NiMn 2 O 4 60-80% of materials; the modified barium titanate is obtained by sintering barium titanate, yttrium oxide and manganese oxide at a high temperature; the molar ratio of the yttrium oxide to the manganese oxide is 1: (5-10), wherein the sum of the addition amounts of the yttrium oxide and the manganese oxide accounts for 0.1-1% of the barium titanate;
the raw materials for preparing the protective layer comprise: 50-60% of water glass and 40-50% of nano alumina.
2. The high-stability high-power ceramic resistor of claim 1, wherein the raw materials for preparing the resistor matrix further comprise: a binder and water; the raw materials for preparing the protective layer also comprise: and (3) water.
3. The high-stability high-power ceramic resistor according to claim 1, wherein the thickness of the protective layer is 10-200 microns.
4. The high-stability high-power ceramic resistor of claim 1, further comprising a metal electrode, an electrode cap, and a lead-out wire; the metal electrodes are arranged on the end surfaces of the two ends of the resistor matrix coated with the protective layer and are contacted with the electrode caps through solder paste; the two electrode caps are respectively sleeved on the end surfaces of the two ends of the resistor matrix and are in contact with the protective layer, and the outer sides of the two electrode caps are respectively connected with the lead-out wires.
5. A method for preparing the high-stability high-power ceramic resistor according to any one of claims 1 to 4, comprising the following steps:
preparing a resistor matrix: mixing acetylene black, bentonite, wollastonite and/or alumina, a resistance modifier, a binder and water, ball milling, granulating, press forming and sintering for one time to obtain a resistance matrix;
and (3) coating a protective layer: mixing water glass, nano alumina and water, ball milling, coating on the outer periphery of the resistor matrix, and performing secondary sintering to form a protective layer coated on the resistor matrix on the outer periphery of the resistor matrix.
6. The method for preparing the high-stability high-power ceramic resistor according to claim 5, wherein the temperature of the primary sintering is 940-1300 ℃, and the time of the primary sintering is 100-150 min; the temperature of the secondary sintering is 860-900 ℃, and the time of the secondary sintering is 10-30 min; the primary sintering and the secondary sintering are both performed under an inert atmosphere.
7. The method for manufacturing a high-stability high-power ceramic resistor according to claim 5, further comprising:
spraying a metal electrode: spraying the metal electrode on the end surfaces of the two ends of the resistor matrix coated with the protective layer;
welding an electrode cap: coating solder paste on the end surfaces of two ends of a resistor matrix sprayed with a metal electrode, covering an electrode cap, and welding the electrode cap on two ends of the resistor matrix through reflow soldering;
welding lead-out wires: and welding lead-out wires on the two electrode caps to obtain a resistor finished product.
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US3996168A (en) * 1973-02-19 1976-12-07 Siemens Aktiengesellschaft Ceramic electrical resistor
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Publication number Priority date Publication date Assignee Title
US3996168A (en) * 1973-02-19 1976-12-07 Siemens Aktiengesellschaft Ceramic electrical resistor
CN103319161A (en) * 2013-06-14 2013-09-25 西安交通大学 Composite aluminum oxide ceramic resistance material for large-power resistance element and preparation method thereof
CN111559913A (en) * 2020-06-05 2020-08-21 西安交通大学 Carbon ceramic linear resistor and preparation method of side composite insulating layer thereof

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