CN109020534B - Preparation method of ZnO linear resistor with adjustable porosity - Google Patents

Preparation method of ZnO linear resistor with adjustable porosity Download PDF

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CN109020534B
CN109020534B CN201810883767.1A CN201810883767A CN109020534B CN 109020534 B CN109020534 B CN 109020534B CN 201810883767 A CN201810883767 A CN 201810883767A CN 109020534 B CN109020534 B CN 109020534B
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zno
zno linear
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linear resistor
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CN109020534A (en
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任鑫
徐希
姚政
施利毅
时雯
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University of Shanghai for Science and Technology
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    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/453—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on zinc, tin, or bismuth oxides or solid solutions thereof with other oxides, e.g. zincates, stannates or bismuthates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C17/00—Apparatus or processes specially adapted for manufacturing resistors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C17/00—Apparatus or processes specially adapted for manufacturing resistors
    • H01C17/30—Apparatus or processes specially adapted for manufacturing resistors adapted for baking
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    • C04B2235/42—Non metallic elements added as constituents or additives, e.g. sulfur, phosphor, selenium or tellurium
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Abstract

The invention discloses a preparation method of ZnO linear resistor with adjustable porosity, which does not add additional process in the process of preparing ZnO linear resistor, is simple and easy to operate, and can effectively remove graphite powder introduced in the process of preparing ZnO linear resistor. The graphite powder is nontoxic, low in price and easy to obtain, organic matter volatilization and carbon gasification products in the sintering process are easy to collect and process, no environmental pollution is caused, and no residue is left after sintering. Under the conditions of not changing the components of the ZnO linear resistance element and not influencing the performance of the ZnO linear resistance element, the method can realize the precise regulation and control of the porosity of the ZnO linear resistance element so as to meet various requirements of heat dissipation, strength and light weight, and the prepared ZnO linear resistance element can meet the application requirements of more occasions.

Description

Preparation method of ZnO linear resistor with adjustable porosity
Technical Field
The invention relates to a preparation method of a linear resistor, in particular to a preparation method of a ZnO linear resistor, which is applied to the technical field of resistance electrical elements.
Background
The ZnO ceramic linear resistor is an electrical element with high energy density and good linearity, is less influenced by temperature, has a small positive resistance temperature coefficient, and is generally applied to various energy absorption occasions. However, the porosity of the existing ZnO linear resistor is difficult to control, the requirements of heat dissipation, strength and light weight cannot be met, and the existing ZnO linear resistor cannot meet the use requirements of more occasions, so that the technical problem to be solved is urgently needed.
Disclosure of Invention
In order to solve the problems of the prior art, the invention aims to overcome the defects in the prior art and provide the preparation method of the ZnO linear resistor with the adjustable porosity. The invention has simple process, easy control and low cost.
In order to achieve the purpose, the invention adopts the following technical scheme:
a preparation method of ZnO linear resistor with adjustable porosity comprises the following steps:
a. preparation of the additive:
a1. ZnO powder and Al2O3Mixing the powder, MgO powder and deionized water, adding the mixture into a ball mill, performing ball milling for at least 24 hours, sieving the mixture through a 120-mesh sieve, and collecting mixed slurry;
a2. then drying the mixed slurry at the temperature of 100-120 ℃, crushing the dried mixed slurry into powder, calcining the obtained powder at the high temperature of 1050-1250 ℃ for at least 2h, crushing the calcined product, and sieving the calcined product by a 30-mesh sieve to obtain the powder;
a3. mixing the powder with deionized water to reach a solid content of 60% by mass, adding the mixture into a ball mill, performing ball milling for at least 48 hours to enable the particle size of the mixed slurry to reach 0.5-2 mu m, and drying and crushing the mixture to obtain additive powder;
b. preparing total slurry:
mixing the additive powder prepared in the step a with a ZnO powder main material, graphite powder, a binder and deionized water, adding the mixture into a ball mill, carrying out ball milling for at least 24 hours, and sieving the obtained slurry with a 250-mesh sieve to obtain total slurry; wherein the adding amount of the graphite powder of the total slurry ingredients calculated by mass is 1-10% of the dry weight of the total slurry after water removal;
c. preparing a blank body:
c1. b, performing spray granulation on the total slurry prepared in the step b by using a spray dryer to obtain granulated materials;
c2. adding deionized water and a release agent into the obtained granulated material, uniformly mixing, sieving by a 30-mesh sieve, and then carrying out ageing treatment on the sieved and collected powder for at least 20 hours to ensure that the mass percentage moisture content of the powder is 1.3-1.6%, thus obtaining blank making powder;
c3. the obtained blank making powder is subjected to pressure forming, and the pressure is controlled to ensure that the density of the formed blank is 2.80-3.05g/cm3；
d. Preparing a finished ZnO linear resistance element:
d1. c, carrying out high-temperature glue removal treatment at 400-500 ℃ on the green body prepared in the step c, and discharging organic matters in the green body;
d2. pre-calcining the blank subjected to the glue removal treatment at the high temperature of 600-1000 ℃ for at least 3.5h, and removing graphite components in the blank;
d3. then calcining the pre-calcined green body at 1250-1400 ℃ for at least 3.5h to obtain a sintered green body;
d4. grinding and cleaning the obtained sintered blank to obtain a ZnO linear resistance element section, and then preparing a metal electrode on the surface of the processed ZnO linear resistance element section to obtain a finished ZnO linear resistance element;
and c, adjusting the carbon doping amount of the ZnO linear resistor blank by controlling the adding amount of the graphite powder in the step b, and further controlling the porosity of the finished ZnO linear resistor element prepared in the step d.
As a preferable technical scheme of the present invention, in the step b, the additive powder, the ZnO powder main material, and the graphite powder prepared in the step a are mixed according to a mass ratio of 500: 1000: (15-135) in the above ratio.
As a preferable technical scheme of the invention, in the step d2 of the step d, the green body after the binder removal treatment is subjected to high-temperature precalcination at the temperature of 800-.
In the step d, the porosity of the prepared finished ZnO linear resistor element is 10-30%, and the resistivity is 200-1000 omega cm. Further preferably, the obtained finished ZnO linear resistor element has the porosity of 11.03-28.77% and the resistivity of 209-925 Ω & cm.
As a preferable technical scheme of the invention, in the step a2 of the step a, the obtained powder is calcined for at least 2 hours at 1150-1250 ℃ to obtain a calcined product.
In the step a3 of the step a, the powder is mixed with deionized water and ball milled, so that the particle size of the mixed slurry reaches 0.5-0.907 μm.
As a preferred technical scheme of the invention, in the step b, the solid average particle size of the prepared total slurry is 629-1160 nm.
As a preferable technical proposal of the invention, in the step c2 of the step c, the mass percent water content of the obtained blank making powder is 1.37-1.52%.
As a preferred technical proposal of the invention, in the step c3 of the step c, the density of the formed blank is 2.82-2.99g/cm3。
Compared with the prior art, the invention has the following obvious and prominent substantive characteristics and remarkable advantages:
1. the method adopts various high-quality metal oxide raw materials of zinc oxide, aluminum oxide and magnesium oxide as main materials, then adds graphite powder for mixing, prepares the ZnO linear resistor through a forming process and a glue discharging-pre-calcining-high temperature calcining multi-step method, and achieves the purpose of adjusting the porosity of the ZnO linear resistor by adding graphite materials with different contents so as to meet various requirements of heat dissipation, strength and light weight;
2. in the process of preparing the ZnO linear resistor, no additional process is needed, the method is simple and has operation, and the graphite powder introduced in the process of preparing the ZnO linear resistor can be effectively removed;
3. the method can realize the accurate regulation and control of the porosity of the ZnO linear resistance element under the conditions of not changing the components of the ZnO linear resistance element and not influencing the performance of the ZnO linear resistance element, and the prepared finished product ZnO linear resistance element has the porosity of 10-30 percent and the resistivity of 200-1000 omega-cm.
The above-described scheme is further illustrated below with reference to specific embodiments, which are detailed below:
example one
In this embodiment, a method for preparing a ZnO linear resistor includes the following specific steps:
a. preparation of the additive:
a1. 627g of ZnO powder, 393g of Al2O3Mixing the powder, 78g of MgO powder and 3000g of deionized water, adding the mixture into a ball mill, carrying out ball milling for 24 hours, sieving the mixture through a 120-mesh sieve, and collecting mixed slurry;
a2. then drying the mixed slurry at the temperature of 100-120 ℃, crushing the dried mixed slurry into powder, calcining the obtained powder at the high temperature of 1150 ℃ for 2 hours, crushing the calcined product, and sieving the crushed calcined product with a 30-mesh sieve to obtain powder;
a3. mixing the powder with deionized water to reach a solid content of 60% by mass, adding the mixture into a ball mill, carrying out ball milling for 48 hours to enable the particle size of the mixed slurry to reach 0.907 mu m, and drying and crushing to obtain additive powder;
b. preparing total slurry:
mixing 500g of the additive powder prepared in the step a with 1000g of ZnO powder main material, 15g of graphite powder, 14g of binder and 1000g of deionized water, adding the mixture into a ball mill, carrying out ball milling for 24 hours, and sieving the obtained slurry with a 250-mesh sieve to obtain total slurry, wherein the average solid particle size of the prepared total slurry is 629 nm;
c. preparing a blank body:
c1. c, adopting a spray dryer, controlling the air inlet temperature to be 220 ℃ and the air outlet temperature to be 110 ℃, and carrying out spray granulation on the total slurry prepared in the step b to obtain granules;
c2. adding deionized water and a release agent into the obtained granulated material, uniformly mixing, sieving by a 30-mesh sieve, and then carrying out aging treatment on the sieved and collected powder for 20 hours to enable the mass percent water content of the powder to be 1.50% so as to obtain blank making powder;
c3. the obtained blank making powder is subjected to pressure forming by a hydraulic press, and the density of the formed blank is 2.98g/cm by adjusting the pressure of the hydraulic press3；
d. Preparing a finished ZnO linear resistance element:
d1. c, carrying out high-temperature glue removal treatment at 450 ℃ on the green body prepared in the step c, and discharging organic matters in the green body;
d2. pre-calcining the blank subjected to the glue removing treatment at the high temperature of 800 ℃ for 3.5 hours to remove graphite components in the blank;
d3. then calcining the pre-calcined green body at the high temperature of 1320 ℃ for 3.5h to obtain a sintered green body;
d4. grinding and cleaning the obtained sintered blank to obtain a ZnO linear resistance element section, and then preparing an aluminum electrode on the surface of the processed ZnO linear resistance element section to obtain a finished ZnO linear resistance element;
in this embodiment, the amount of carbon doped in the ZnO varistor blank is controlled by controlling the amount of graphite powder added in step b, and the porosity of the finished ZnO varistor element obtained in step d is further controlled. According to the preparation method of the ZnO linear resistor, no additional process is added in the preparation process of the ZnO linear resistor, the method is simple and easy to operate, and graphite powder introduced in the preparation process of the ZnO linear resistor can be effectively removed. The ZnO varistor element produced in this example had no change in composition, the electrical characteristics of the ZnO varistor element were not reduced, the linearity, the temperature resistance coefficient, and the energy density of the ZnO varistor element were not significantly affected, the porosity was 11.03%, and the resistivity was 209 Ω · cm. The method adopts various high-quality metal oxide raw materials of zinc oxide, aluminum oxide and magnesium oxide as main materials, then graphite powder is added for mixing, ZnO linear resistors are prepared through a forming process and a glue discharging-pre-calcining-high temperature calcining multi-step method, and the aim of adjusting the porosity of the ZnO linear resistors is achieved through controlling the added graphite materials, so that various requirements of specific heat dissipation, strength and light weight are met.
Example two
This embodiment is substantially the same as the first embodiment, and is characterized in that:
in this embodiment, a method for preparing a ZnO linear resistor includes the following specific steps:
a. preparation of the additive:
a1. 627g of ZnO powder, 393g of Al2O3Mixing the powder, 78g of MgO powder and 3000g of deionized water, adding the mixture into a ball mill, carrying out ball milling for 24 hours, sieving the mixture through a 120-mesh sieve, and collecting mixed slurry;
a2. then drying the mixed slurry at the temperature of 100-120 ℃, crushing the dried mixed slurry into powder, calcining the obtained powder at the high temperature of 1150 ℃ for 2 hours, crushing the calcined product, and sieving the crushed calcined product with a 30-mesh sieve to obtain powder;
a3. mixing the powder with deionized water to reach a solid content of 60% by mass, adding the mixture into a ball mill, carrying out ball milling for 48 hours to enable the particle size of the mixed slurry to reach 0.907 mu m, and drying and crushing to obtain additive powder;
b. preparing total slurry:
mixing 500g of the additive powder prepared in the step a with 1000g of ZnO powder main material, 30g of graphite powder, 14g of binder and 1000g of deionized water, adding the mixture into a ball mill, carrying out ball milling for 24 hours, and sieving the obtained slurry with a 250-mesh sieve to obtain total slurry, wherein the average solid particle size of the prepared total slurry is 797 nm;
c. preparing a blank body:
c1. c, adopting a spray dryer, controlling the air inlet temperature to be 220 ℃ and the air outlet temperature to be 110 ℃, and carrying out spray granulation on the total slurry prepared in the step b to obtain granules;
c2. adding deionized water and a release agent into the obtained granulated material, uniformly mixing, sieving by a 30-mesh sieve, and then carrying out ageing treatment on the sieved and collected powder for 20 hours to enable the mass percentage moisture content of the powder to be 1.52% so as to obtain blank making powder;
c3. the obtained blank making powder is subjected to pressure forming by a hydraulic press, and the density of the formed blank is 2.98g/cm by adjusting the pressure of the hydraulic press3；
d. Preparing a finished ZnO linear resistance element:
d1. c, carrying out high-temperature glue removal treatment at 450 ℃ on the green body prepared in the step c, and discharging organic matters in the green body;
d2. pre-calcining the blank subjected to the glue removing treatment at the high temperature of 800 ℃ for 3.5 hours to remove graphite components in the blank;
d3. then calcining the pre-calcined green body at the high temperature of 1320 ℃ for 3.5h to obtain a sintered green body;
d4. grinding and cleaning the obtained sintered blank to obtain a ZnO linear resistance element section, and then preparing an aluminum electrode on the surface of the processed ZnO linear resistance element section to obtain a finished ZnO linear resistance element;
in this embodiment, the amount of carbon doped in the ZnO varistor blank is controlled by controlling the amount of graphite powder added in step b, and the porosity of the finished ZnO varistor element obtained in step d is further controlled. According to the preparation method of the ZnO linear resistor, no additional process is added in the preparation process of the ZnO linear resistor, the method is simple and easy to operate, and graphite powder introduced in the preparation process of the ZnO linear resistor can be effectively removed. The ZnO varistor element prepared in this example had no change in composition, the electrical characteristics of the ZnO varistor element were not reduced, the linearity, the temperature resistance coefficient, and the energy density of the ZnO varistor element were not significantly affected, the porosity was 14.94%, and the resistivity was 260 Ω · cm. The method adopts various high-quality metal oxide raw materials of zinc oxide, aluminum oxide and magnesium oxide as main materials, then graphite powder is added for mixing, ZnO linear resistors are prepared through a forming process and a glue discharging-pre-calcining-high temperature calcining multi-step method, and the aim of adjusting the porosity of the ZnO linear resistors is achieved through controlling the added graphite materials, so that various requirements of specific heat dissipation, strength and light weight are met.
EXAMPLE III
This embodiment is substantially the same as the previous embodiment, and is characterized in that:
in this embodiment, a method for preparing a ZnO linear resistor includes the following specific steps:
a. preparation of the additive:
a1. 627g of ZnO powder, 393g of Al2O3Mixing the powder, 78g of MgO powder and 3000g of deionized water, adding the mixture into a ball mill, carrying out ball milling for 24 hours, sieving the mixture through a 120-mesh sieve, and collecting mixed slurry;
a2. then drying the mixed slurry at the temperature of 100-120 ℃, crushing the dried mixed slurry into powder, calcining the obtained powder at the high temperature of 1150 ℃ for 2 hours, crushing the calcined product, and sieving the crushed calcined product with a 30-mesh sieve to obtain powder;
a3. mixing the powder with deionized water to reach a solid content of 60% by mass, adding the mixture into a ball mill, carrying out ball milling for 48 hours to enable the particle size of the mixed slurry to reach 0.907 mu m, and drying and crushing to obtain additive powder;
b. preparing total slurry:
mixing 500g of the additive powder prepared in the step a with 1000g of ZnO powder main material, 45g of graphite powder, 14g of binder and 1000g of deionized water, adding the mixture into a ball mill, carrying out ball milling for 24 hours, and sieving the obtained slurry with a 250-mesh sieve to obtain total slurry, wherein the average solid particle size of the prepared total slurry is 950 nm;
c. preparing a blank body:
c1. c, adopting a spray dryer, controlling the air inlet temperature to be 220 ℃ and the air outlet temperature to be 110 ℃, and carrying out spray granulation on the total slurry prepared in the step b to obtain granules;
c2. adding deionized water and a release agent into the obtained granulated material, uniformly mixing, sieving by a 30-mesh sieve, and then carrying out aging treatment on the sieved and collected powder for 20 hours to enable the mass percent water content of the powder to be 1.37% so as to obtain blank making powder;
c3. the obtained blank making powder is subjected to pressure forming by a hydraulic press, and the density of the formed blank is 2.99g/cm by adjusting the pressure of the hydraulic press3；
d. Preparing a finished ZnO linear resistance element:
d1. c, carrying out high-temperature glue removal treatment at 450 ℃ on the green body prepared in the step c, and discharging organic matters in the green body;
d2. pre-calcining the blank subjected to the glue removing treatment at the high temperature of 800 ℃ for 3.5 hours to remove graphite components in the blank;
d3. then calcining the pre-calcined green body at the high temperature of 1320 ℃ for 3.5h to obtain a sintered green body;
d4. grinding and cleaning the obtained sintered blank to obtain a ZnO linear resistance element section, and then preparing an aluminum electrode on the surface of the processed ZnO linear resistance element section to obtain a finished ZnO linear resistance element;
in this embodiment, the amount of carbon doped in the ZnO varistor blank is controlled by controlling the amount of graphite powder added in step b, and the porosity of the finished ZnO varistor element obtained in step d is further controlled. According to the preparation method of the ZnO linear resistor, no additional process is added in the preparation process of the ZnO linear resistor, the method is simple and easy to operate, and graphite powder introduced in the preparation process of the ZnO linear resistor can be effectively removed. The ZnO varistor element prepared in this example had no change in composition, the electrical characteristics of the ZnO varistor element were not reduced, the linearity, the temperature resistance coefficient, and the energy density of the ZnO varistor element were not significantly affected, the porosity was 20.21%, and the resistivity was 401 Ω · cm. The method adopts various high-quality metal oxide raw materials of zinc oxide, aluminum oxide and magnesium oxide as main materials, then graphite powder is added for mixing, ZnO linear resistors are prepared through a forming process and a glue discharging-pre-calcining-high temperature calcining multi-step method, and the aim of adjusting the porosity of the ZnO linear resistors is achieved through controlling the added graphite materials, so that various requirements of specific heat dissipation, strength and light weight are met.
Example four
This embodiment is substantially the same as the previous embodiment, and is characterized in that:
in this embodiment, a method for preparing a ZnO linear resistor includes the following specific steps:
a. preparation of the additive:
a1. 627g of ZnO powder, 393g of Al2O3Mixing the powder, 78g of MgO powder and 3000g of deionized water, adding the mixture into a ball mill, carrying out ball milling for 24 hours, sieving the mixture through a 120-mesh sieve, and collecting mixed slurry;
a2. then drying the mixed slurry at the temperature of 100-120 ℃, crushing the dried mixed slurry into powder, calcining the obtained powder at the high temperature of 1150 ℃ for 2 hours, crushing the calcined product, and sieving the crushed calcined product with a 30-mesh sieve to obtain powder;
a3. mixing the powder with deionized water to reach a solid content of 60% by mass, adding the mixture into a ball mill, carrying out ball milling for 48 hours to enable the particle size of the mixed slurry to reach 0.907 mu m, and drying and crushing to obtain additive powder;
b. preparing total slurry:
mixing 500g of the additive powder prepared in the step a with 1000g of ZnO powder main material, 135g of graphite powder, 14g of binder and 1000g of deionized water, adding the mixture into a ball mill, carrying out ball milling for 24 hours, and sieving the obtained slurry with a 250-mesh sieve to obtain total slurry, wherein the average solid particle size of the prepared total slurry is 1.16 mu m;
c. preparing a blank body:
c1. c, adopting a spray dryer, controlling the air inlet temperature to be 220 ℃ and the air outlet temperature to be 110 ℃, and carrying out spray granulation on the total slurry prepared in the step b to obtain granules;
c2. adding deionized water and a release agent into the obtained granulated material, uniformly mixing, sieving by a 30-mesh sieve, and then carrying out aging treatment on the sieved and collected powder for 20 hours to enable the mass percent water content of the powder to be 1.43% so as to obtain blank making powder;
c3. the obtained blank making powder is subjected to pressure forming by a hydraulic press, and the density of the formed blank is 2.83g/cm by adjusting the pressure of the hydraulic press3；
d. Preparing a finished ZnO linear resistance element:
d1. c, carrying out high-temperature glue removal treatment at 450 ℃ on the green body prepared in the step c, and discharging organic matters in the green body;
d2. pre-calcining the blank subjected to the glue removing treatment at the high temperature of 800 ℃ for 3.5 hours to remove graphite components in the blank;
d3. then calcining the pre-calcined green body at the high temperature of 1320 ℃ for 3.5h to obtain a sintered green body;
d4. grinding and cleaning the obtained sintered blank to obtain a ZnO linear resistance element section, and then preparing an aluminum electrode on the surface of the processed ZnO linear resistance element section to obtain a finished ZnO linear resistance element;
in this embodiment, the amount of carbon doped in the ZnO varistor blank is controlled by controlling the amount of graphite powder added in step b, and the porosity of the finished ZnO varistor element obtained in step d is further controlled. According to the preparation method of the ZnO linear resistor, no additional process is added in the preparation process of the ZnO linear resistor, the method is simple and easy to operate, and graphite powder introduced in the preparation process of the ZnO linear resistor can be effectively removed. The ZnO varistor element prepared in this example had no change in composition, the electrical characteristics of the ZnO varistor element were not reduced, the linearity, the temperature resistance coefficient, and the energy density of the ZnO varistor element were not significantly affected, the porosity was 28.77%, and the resistivity was 925 Ω · cm. The method adopts various high-quality metal oxide raw materials of zinc oxide, aluminum oxide and magnesium oxide as main materials, then graphite powder is added for mixing, ZnO linear resistors are prepared through a forming process and a glue discharging-pre-calcining-high temperature calcining multi-step method, and the aim of adjusting the porosity of the ZnO linear resistors is achieved through controlling the added graphite materials, so that various requirements of specific heat dissipation, strength and light weight are met.
In summary, in the embodiments, the preparation method of the ZnO linear resistor with adjustable porosity is adopted, the carbon gasification removal process of the high-temperature pre-sintering carbon is performed after the carbon doping is performed, no additional process is added in the preparation process of the ZnO linear resistor, the method is simple and easy to operate, and the graphite powder introduced in the preparation process of the ZnO linear resistor can be effectively removed. The graphite powder is nontoxic, low in price and easy to obtain, organic matter volatilization and carbon gasification products in the sintering process are easy to collect and process, no environmental pollution is caused, and no residue is left after sintering. Under the conditions of not changing the components of the ZnO linear resistance element and not influencing the performance of the ZnO linear resistance element, the method can realize the precise regulation and control of the porosity of the ZnO linear resistance element so as to meet various requirements of heat dissipation, strength and light weight, and the prepared ZnO linear resistance element can meet the application requirements of more occasions.
While the embodiments of the present invention have been described, the present invention is not limited to the above embodiments, and various changes and modifications may be made according to the purpose of the invention, and any changes, modifications, substitutions, combinations or simplifications made according to the spirit and principle of the technical solution of the present invention shall be equivalent substitution ways, so long as the technical principle and inventive concept of the method for preparing the adjustable porosity ZnO linear resistor according to the present invention are met, and all fall within the protection scope of the present invention.

Claims (10)

1. A preparation method of ZnO linear resistor with adjustable porosity is characterized by comprising the following steps:
a. preparation of the additive:
a1. ZnO powder and Al2O3Mixing the powder, MgO powder and deionized water, adding the mixture into a ball mill, performing ball milling for at least 24 hours, sieving the mixture through a 120-mesh sieve, and collecting mixed slurry;
a2. then drying the mixed slurry at the temperature of 100-120 ℃, crushing the dried mixed slurry into powder, calcining the obtained powder at the high temperature of 1050-1250 ℃ for at least 2h, crushing the calcined product, and sieving the calcined product by a 30-mesh sieve to obtain the powder;
a3. mixing the powder with deionized water to reach a solid content of 60% by mass, adding the mixture into a ball mill, performing ball milling for at least 48 hours to enable the particle size of the mixed slurry to reach 0.5-2 mu m, and drying and crushing the mixture to obtain additive powder;
b. preparing total slurry:
mixing the additive powder prepared in the step a with a ZnO powder main material, graphite powder, a binder and deionized water, adding the mixture into a ball mill, carrying out ball milling for at least 24 hours, and sieving the obtained slurry with a 250-mesh sieve to obtain total slurry; wherein the adding amount of the graphite powder of the total slurry ingredients calculated by mass is 1-10% of the dry weight of the total slurry after water removal;
c. preparing a blank body:
c1. b, performing spray granulation on the total slurry prepared in the step b by using a spray dryer to obtain granulated materials;
c2. adding deionized water and a release agent into the obtained granulated material, uniformly mixing, sieving by a 30-mesh sieve, and then carrying out ageing treatment on the sieved and collected powder for at least 20 hours to ensure that the mass percentage moisture content of the powder is 1.3-1.6%, thus obtaining blank making powder;
c3. the obtained blank making powder is subjected to pressure forming, and the pressure is controlled to ensure that the density of the formed blank is 2.80-3.05g/cm3；
d. Preparing a finished ZnO linear resistance element:
d1. c, carrying out high-temperature glue removal treatment at 400-500 ℃ on the green body prepared in the step c, and discharging organic matters in the green body;
d2. pre-calcining the blank subjected to the glue removal treatment at the high temperature of 600-1000 ℃ for at least 3.5h, and removing graphite components in the blank;
d3. then calcining the pre-calcined green body at 1250-1400 ℃ for at least 3.5h to obtain a sintered green body;
d4. grinding and cleaning the obtained sintered blank to obtain a ZnO linear resistance element section, and then preparing a metal electrode on the surface of the processed ZnO linear resistance element section to obtain a finished ZnO linear resistance element;
and c, adjusting the carbon doping amount of the ZnO linear resistor blank by controlling the adding amount of the graphite powder in the step b, and further controlling the porosity of the finished ZnO linear resistor element prepared in the step d.
2. The preparation method of the adjustable porosity ZnO linear resistor according to claim 1, characterized by comprising the following steps: in the step b, the additive powder, the ZnO powder main material and the graphite powder prepared in the step a are mixed according to the mass ratio of 500: 1000: (15-135) in the above ratio.
3. The preparation method of the adjustable porosity ZnO linear resistor according to claim 1, characterized by comprising the following steps: in the step d2 of the step d, the green body after the glue removing treatment is subjected to high-temperature precalcination at 800-1000 ℃, so as to remove graphite components in the green body.
4. The preparation method of the ZnO linear resistor with the adjustable porosity according to any one of claims 1 to 3, which is characterized by comprising the following steps: in the step d, the porosity of the prepared finished ZnO linear resistance element is 10-30%, and the resistivity is 200-1000 omega-cm.
5. The preparation method of the adjustable porosity ZnO linear resistor according to claim 4, characterized by comprising the following steps: in the step d, the prepared finished ZnO linear resistance element has the porosity of 11.03-28.77% and the resistivity of 209-925 omega-cm.
6. The preparation method of the ZnO linear resistor with the adjustable porosity according to any one of claims 1 to 3, which is characterized by comprising the following steps: in the step a2 of the step a, the obtained powder is calcined at 1150-1250 ℃ for at least 2h to obtain a calcined product.
7. The preparation method of the ZnO linear resistor with the adjustable porosity according to any one of claims 1 to 3, which is characterized by comprising the following steps: in step a3 of step a, the powder is mixed with deionized water and ball milled, so that the particle size of the mixed slurry reaches 0.5-0.907 μm.
8. The preparation method of the ZnO linear resistor with the adjustable porosity according to any one of claims 1 to 3, which is characterized by comprising the following steps: in the step b, the average solid particle size of the prepared total slurry was 629-1160 nm.
9. The preparation method of the ZnO linear resistor with the adjustable porosity according to any one of claims 1 to 3, which is characterized by comprising the following steps: in the step c2 of the step c, the mass percent water content of the obtained blank making powder is 1.37-1.52%.
10. The preparation method of the ZnO linear resistor with the adjustable porosity according to any one of claims 1 to 3, which is characterized by comprising the following steps: in the step c3 of the step c, the density of the formed blank is 2.82-2.99g/cm3。
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Citations (2)

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Publication number Priority date Publication date Assignee Title
JPH03103762A (en) * 1989-09-18 1991-04-30 Sekisui Plastics Co Ltd Moisture sensitive material and moisture sensitive element
CN107619281A (en) * 2017-08-03 2018-01-23 浙江理工大学 A kind of preparation method of low-temperature sintering acid and alkali-resistance porous silicon carbide ceramic supporter

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH03103762A (en) * 1989-09-18 1991-04-30 Sekisui Plastics Co Ltd Moisture sensitive material and moisture sensitive element
CN107619281A (en) * 2017-08-03 2018-01-23 浙江理工大学 A kind of preparation method of low-temperature sintering acid and alkali-resistance porous silicon carbide ceramic supporter

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* Cited by examiner, † Cited by third party
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