CN111233461A - High surge current withstanding SnO2Method for preparing varistor ceramic - Google Patents
High surge current withstanding SnO2Method for preparing varistor ceramic Download PDFInfo
- Publication number
- CN111233461A CN111233461A CN202010193561.3A CN202010193561A CN111233461A CN 111233461 A CN111233461 A CN 111233461A CN 202010193561 A CN202010193561 A CN 202010193561A CN 111233461 A CN111233461 A CN 111233461A
- Authority
- CN
- China
- Prior art keywords
- sno
- temperature
- preparing
- powder
- slurry
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- 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
- C04B35/457—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 based on tin oxides or stannates
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
- H01C7/10—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material voltage responsive, i.e. varistors
- H01C7/105—Varistor cores
- H01C7/108—Metal oxide
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
- C04B2235/3231—Refractory metal oxides, their mixed metal oxides, or oxide-forming salts thereof
- C04B2235/3232—Titanium oxides or titanates, e.g. rutile or anatase
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
- C04B2235/3231—Refractory metal oxides, their mixed metal oxides, or oxide-forming salts thereof
- C04B2235/3241—Chromium oxides, chromates, or oxide-forming salts thereof
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
- C04B2235/3231—Refractory metal oxides, their mixed metal oxides, or oxide-forming salts thereof
- C04B2235/3251—Niobium oxides, niobates, tantalum oxides, tantalates, or oxide-forming salts thereof
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
- C04B2235/3231—Refractory metal oxides, their mixed metal oxides, or oxide-forming salts thereof
- C04B2235/3258—Tungsten oxides, tungstates, or oxide-forming salts thereof
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
- C04B2235/327—Iron group oxides, their mixed metal oxides, or oxide-forming salts thereof
- C04B2235/3275—Cobalt oxides, cobaltates or cobaltites or oxide forming salts thereof, e.g. bismuth cobaltate, zinc cobaltite
- C04B2235/3277—Co3O4
Abstract
High-surge-current-tolerance SnO2The method for preparing the varistor ceramic comprises the steps of raw material preparation, dispersion, drying, molding, binder removal and sintering, and is characterized in that titanium ions and tungsten ions are added in the step of raw material preparation, and the too ions are Ta2O5Added in the form of WO3And (4) adding in a form. The beneficial effects are as follows: high nonlinearity, low leakage current, high surge current resistance and high thermal conductivity, and is more suitable for SnO in the high-voltage field2And (5) the application requirement of the voltage dependent resistor valve plate.
Description
Technical Field
The invention belongs to the field of electrical materials, and particularly relates to a method for preparing SnO2 piezoresistor ceramic with high surge current resistance and low leakage current by adopting mixed doping of trace titanium ions and tungsten ions.
Background
Metal oxide varistors having non-linear current density-electric field (J-E) characteristics are widely used to protect electrical and electronic components from unwanted electrical surges.
The J-E curve of a varistor shows three main regions, namely a pre-breakdown region, a breakdown region and a flip region, the breakdown electric field (Eb) and the nonlinear coefficient (α) defined in the breakdown region are the two most important parameters of the varistor, surge current resistance, residual voltage ratio (Kr) and destructive discharge current are the other key parameters defined in the flip region, high nonlinear coefficient (α) is an ideal requirement in applications, but surge resistance is more important, ZnO varistors have satisfactorily met the above criteria and have been widely used in high and low voltage devices since 1976.
In 1995, with SnO2The advent of varistors has made this new material a popular candidate for replacing ZnO varistors for high voltage applications due to their simpler microstructure, higher breakdown field and better thermal stability in dc degradation testing. However, SnO2The problem of low surge resistance of piezoresistors in high voltage applications has not been solved.
It has been reported in the literature that 98.9 mol% SnO 2-1 mol% CoO-0.05 mol% Nb2O 5-0.05 mol% Cr2O3 (SCNCr composition) was added with 0.05 mol% Y2O3, and an improvement in inrush current resistance was 2500A/cm2. This value is still much lower than that of ZnO varistor (about 6500A/cm for high voltage applications)2). The SnO2 piezoresistor may form many ineffective barriers in the sintering process due to poor uniformity of doped ions, or form effective contact points between crystal grains due to high porosity. These may all be SnO2The piezoresistor has low surge current resistance.
When the lines of the piezoresistor device and each meter work normally, a certain amount of current passes through the piezoresistor, and the current flowing through the piezoresistor is called leakage current. The leakage current is used as a parameter for describing the current-voltage characteristic of the pre-breakdown region. Since leakage current increases as voltage and temperature increase, the above-mentioned factors must be taken into account when using. In recent years, though, high-gradient and highly non-linear SnO2 piezoresistors have been produced. However, the problem of high leakage current of the varistor has not been solved. For the piezoresistor to operate stably, the leakage current should be as small as possible.
Although there are already many highly non-linear, high voltage gradient SnO2The successful development of the piezoresistor, the high non-linear value does not mean good performance in a large current region. For a varistor to be used for protecting an electrical or electronic circuit against transient voltage surges caused by lightning or switching, a high non-linearity value is basically required, but more importantly, it should be able to withstand the surge currents. At the same time, to ensure the formation of SnO2The piezoresistor works stably at power frequency, so that the research on high current performance and low leakage current is to develop SnO2An important task for base piezoresistive materials.
Disclosure of Invention
The invention aims to solve the problems and designs a high surge current resistant SnO2A method of making a varistor ceramic. The specific design scheme is as follows:
high-surge-current-tolerance SnO2The method for preparing the varistor ceramic comprises the steps of raw material preparation, dispersion, drying, molding, binder removal and sintering, and is characterized in that titanium ions and tungsten ions are added in the step of raw material preparation, and the too ions are Ta2O5Added in the form of WO3And (4) adding in a form.
In the step of preparing the raw materials, the molar mass parts of the components are SnO2：97.82～99.05、Co3O4：0.3～0.55、Nb2O5：0.2～0.3、Ta2O5：0.1～0.2、Cr2O3：0.2～0.25、In2O3：0.02～0.08、WO3：0.03～0.05%、TiO2：0 .1～0.75。
In the step of raw material preparation, PVA and deionized water are added into the raw materials and stirred uniformly to obtain a first slurry.
In the dispersing step, 15-22 mol% of dispersing agent is added into the slurry and stirred, so that the added dispersing agent is uniformly distributed in the mixed solution, and second slurry is obtained.
In the drying step, the second slurry is put into a planetary ball mill for high-frequency grinding and mixing for 10 hours, so that the powder particles in the second mixed solution reach less than 1 mu m, and then the second mixed solution is dried for 10 hours at the constant temperature of 60 ℃ to obtain the powder.
In the molding step, the powder is crushed and sieved by a sieve with 300 meshes and 450 meshes; pressing the sieved powder into a round embryo body with the diameter of 5cm under the pressure of 20-35 MPa.
In the step of discharging the glue, the blank is discharged at the temperature of 100-500 ℃, the temperature is kept for 6h at the glue discharging temperature, and then the blank is cooled to the room temperature, wherein the heating and cooling rates are respectively 30 ℃/h-120 ℃/h and 30 ℃/h-180 ℃/h.
In the sintering step, the blank body after the glue discharging is sintered at the temperature of 1300-1450 ℃, the temperature is kept for 2-4h at the sintering temperature, and then the blank body is cooled to the room temperature, wherein the temperature rising and reducing rates are respectively 30 ℃/h-120 ℃/h and 300 ℃/h-480 ℃/h.
The method for preparing the high surge current resistant SnO2 piezoresistor ceramic by the technical scheme has the advantages that:
high nonlinearity, low leakage current, high surge current resistance and high thermal conductivity, and is more suitable for SnO in the high-voltage field2And (5) the application requirement of the voltage dependent resistor valve plate.
Detailed Description
The present invention is described in detail below.
High-surge-current-tolerance SnO2The method for preparing the varistor ceramic comprises the steps of raw material preparation, dispersion, drying, molding, binder removal and sintering, and is characterized in that titanium ions and tungsten ions are added in the step of raw material preparation, and the too ions are Ta2O5Added in the form of WO3And (4) adding in a form.
In the step of preparing the raw materials, the molar mass parts of the components are SnO2：97.82～99.05、Co3O4：0.3～0.55、Nb2O5：0.2～0.3、Ta2O5：0.1～0.2、Cr2O3：0.2～0.25、In2O3：0.02～0.08、WO3：0.03～0.05%、TiO2：0 .1～0.75。
In the step of raw material preparation, PVA and deionized water are added into the raw materials and stirred uniformly to obtain a first slurry.
In the dispersing step, 15-22 mol% of dispersing agent is added into the slurry and stirred, so that the added dispersing agent is uniformly distributed in the mixed solution, and second slurry is obtained.
In the drying step, the second slurry is put into a planetary ball mill for high-frequency grinding and mixing for 10 hours, so that the powder particles in the second mixed solution reach less than 1 mu m, and then the second mixed solution is dried for 10 hours at the constant temperature of 60 ℃ to obtain the powder.
In the molding step, the powder is crushed and sieved by a sieve with 300 meshes and 450 meshes; pressing the sieved powder into a round embryo body with the diameter of 5cm under the pressure of 20-35 MPa.
In the step of discharging the glue, the blank is discharged at the temperature of 100-500 ℃, the temperature is kept for 6h at the glue discharging temperature, and then the blank is cooled to the room temperature, wherein the heating and cooling rates are respectively 30 ℃/h-120 ℃/h and 30 ℃/h-180 ℃/h.
In the sintering step, the blank body after the glue discharging is sintered at the temperature of 1300-1450 ℃, the temperature is kept for 2-4h at the sintering temperature, and then the blank body is cooled to the room temperature, wherein the temperature rising and falling rates are respectively 30 ℃/h-120 ℃/h and 300 ℃/h-480 ℃/h
The invention adopts the method of improving the process and the formula to improve SnO2The performance of the piezoresistor adopts long-time high-frequency grinding SnO2And the mixed slurry of the doping agent is dried and sieved to obtain particles with the diameter smaller than 1um, so that the condition of uneven mixing is improved to a greater extent. In addition, the molding pressure of the tablet is adjusted to 20 to 35MPa, so that SnO is ensured2And under the condition that the resistance card is fully compacted, the cracking caused by overlarge pressure is avoided. In the aspect of improving the formula, the compactness is ensured by doping CoO, and Nb is doped2O5,Ta2O5,Cr2O3Increase its non-linearity, dope In2O3To reduce the residual pressure ratio. Most importantly, in order to achieve the performance indexes of high surge current resistance and low leakage current resistance, the invention dopes TiO2To improve the ability to withstand high surge currents, TiO2In SnO2The varistor plays a dual role in its processing, both as a densification agent and as a grain growth enhancer, without any adverse effect on the electrical properties. In the invention, TiO is added2Can improve SnO2The uniformity of the piezoresistor promotes Ta +5 ions to replace Sn +4 ions so as to improve the conductivity of crystal grains. And finally, the surge current resistance of the SnO2 piezoresistor is improved. By doping WO3To reduce leakage current, because of WO3The addition of (2) limits the growth of crystal grains, does not influence the compactness, and can increase SnO2The resistivity of the base piezoresistor can greatly reduce leakage current and improve voltage gradient. The invention prepares SnO with high surge current resistance and low leakage current2A voltage dependent resistor. The surge current density of the high-voltage current resistor is 4.9-5.5 KA/cm2. Meanwhile, the leakage current density is controlled to be between 1uA/cm and 5 uA/cm. It also possesses a voltage gradient of up to 788V/mm and a nonlinearity of up to 59. The SnO with excellent comprehensive electrical properties, high surge current resistance and low leakage2A voltage dependent resistor.
The following are examples of the present invention:
example one
SnO in this example2The preparation method of the piezoresistor comprises the following steps:
1）SnO2preparation and mixing of main material and dopant
SnO in this practice2The piezoresistor is prepared according to the following proportion: SnO2：98.75%、Co3O4：0.5%、Nb2O5：0.2％、Ta2O5：0.2％、Cr2O3：0.2％、In2O3：0.02％、WO3：0.03%、TiO2: 0.1 percent. Putting the prepared powder into a rubber tank, adding 20mol% of PVA and 450g of deionized water, and uniformly stirring and mixing to prepare first slurry
Adding a dispersing agent
Adding 15mol% of dispersing agent and 450g of deionized water into the first solvent prepared in the step 1), and uniformly stirring to obtain second slurry.
3) Grinding slurry and drying
And (3) putting the second slurry prepared in the step 2) into a planetary ball mill, setting the rotating speed to be 1500 rpm, grinding for 10 hours to enable the particle diameter of the slurry to be less than 1um, then taking out the slurry, putting the slurry into a resistance type air-blast drying box, and setting the constant temperature of 60 ℃ for drying for 10 hours to prepare the moisture-free dry powder.
4) Grinding and granulating of dry powder
Putting the dried powder in the step 3) into a high-frequency grinder for grinding and granulating, wherein the set rotating speed is 550 revolutions per minute, and the time is 6 hours. Repeatedly sieving the ground powder with a 350-mesh sieve. The particle diameter of the sieved powder is smaller than 1 um.
Powder material containing water and tabletting
Spraying 3wt% of deionized water on the powder in the step 4), standing for 8h to enable the powder to fully absorb moisture, and pressing the hydrated powder into a circular blank with the diameter of 5cm by using a molding pressure of 30 Mpa.
6) Glue discharging
Putting the tray for the round blank in the step 5) into a muffle furnace, and discharging glue, wherein the heating rate, the cooling rate and the heat preservation time of the glue discharging are as follows:
the heating rate is as follows:
room temperature to 100 deg.C, 2 deg.C/min
100 to 150 ℃ at 2 ℃/min
150 to 220 ℃ at 1 ℃/min
220 to 300 ℃ at 0.5 ℃/min
300 to 350 ℃, 0.5 ℃/min
350 to 500 ℃, 2 ℃/min
Keeping the temperature at 500 ℃ for 6h
Cooling rate:
500 to 350 ℃, 3 ℃/min
350 to 200 ℃ at 1 ℃/min
200 to 150 ℃ and 0.5 ℃/min
150 ℃ to room temperature, 2 ℃/min
The glue discharging method can completely discharge PVA without influencing the performance of the blank body, and prevents the influence on the varistor caused by carbonization of the residual PVA during sintering in the following sintering.
7) Sintering of round blank
And placing the blank body after the binder removal into a crucible paved with a padding material with the same components to prevent the doped element from being impregnated in the sintering process, so that the loss and the uneven distribution of the dopant are avoided. Placing the crucible filled with the blank body into a high-temperature sintering furnace, strictly sealing the furnace door with asbestos, and sintering in an air atmosphere, wherein the specific sintering temperature rise rate, the specific heat preservation time and the specific temperature reduction rate are as follows:
the heating rate is as follows:
the temperature is raised from room temperature to 100 ℃ at a rate of 1 ℃/min
The temperature rise rate is 2 ℃/min at 100 to 1100 DEG C
1100 to 1250 ℃ and the heating rate is 3 ℃/min
1250 to 1350 ℃, and the heating rate is 2 ℃/min
Keeping the temperature at 1350 ℃ for 4h
Cooling rate:
1350-500 deg.C, cooling rate of 5 deg.C/min
500 to room temperature, and the cooling rate is 8 ℃/min
Finally preparing SnO2A voltage dependent resistor.
For SnO prepared according to the process technology2The piezoresistor is electrically tested. The leakage current is suppressed, and the average value is 4.56A/cm2The mean value of nonlinear coefficient is 41, the mean value of voltage-sensitive voltage gradient is 752V/mm, and the withstand surge current density is 4.9KA/cm2。
Example two
SnO in this example2The preparation method of the piezoresistor comprises the following steps:
1）SnO2preparation and mixing of main material and dopant
SnO in this practice2The piezoresistor is prepared according to the following proportion: SnO2：98.46%、Co3O4：0.5%、Nb2O5：0.3％、Ta2O5：0.2％、Cr2O3：0.25％、In2O3：0.05％、WO3：0.04%、TiO2: 0.2 percent. Putting the prepared powder into a rubber tank, adding 25mol% of PVA and 550g of deionized water, and uniformly stirring and mixing to prepare first slurry
2) Adding a dispersing agent
Adding 20mol% of dispersing agent and 550g of deionized water into the first solvent prepared in the step 1), and uniformly stirring to obtain second slurry.
3) Grinding slurry and drying
And (3) putting the second slurry prepared in the step 2) into a planetary ball mill, setting the rotating speed to be 1500 rpm, grinding for 10 hours to enable the particle diameter of the slurry to be less than 1um, then taking out the slurry, putting the slurry into a resistance type air-blast drying box, and setting the constant temperature of 60 ℃ for drying for 10 hours to prepare the moisture-free dry powder.
4) Grinding and granulating of dry powder
Putting the dried powder in the step 3) into a high-frequency grinder for grinding and granulating, wherein the set rotating speed is 550 revolutions per minute, and the time is 6 hours. And repeatedly sieving the ground powder through a 300-mesh sieve. The particle diameter of the sieved powder is smaller than 1 um.
5) Powder material containing water and tabletting
Spraying 4wt% of deionized water on the powder in the step 4), standing for 8h to enable the powder to fully absorb moisture, and pressing the hydrated powder into a circular blank with the diameter of 5cm by using the molding pressure of 35 Mpa.
6) Glue discharging
Putting the tray for the round blank in the step 5) into a muffle furnace, and discharging glue, wherein the heating rate, the cooling rate and the heat preservation time of the glue discharging are as follows:
the heating rate is as follows:
room temperature to 100 deg.C, 2 deg.C/min
100 to 150 ℃ at 2 ℃/min
150 to 220 ℃ at 1 ℃/min
220 to 300 ℃ at 0.5 ℃/min
300 to 350 ℃, 0.5 ℃/min
350 to 500 ℃ at 2 ℃/min
Keeping the temperature at 500 ℃ for 6h
Cooling rate:
500 to 350 ℃ at 3 ℃/min
350 to 200 ℃ at 1 ℃/min
200 to 150 ℃ at 0.5 ℃/min
150 to room temperature, 2 ℃/min
The glue discharging method can completely discharge PVA without influencing the performance of the blank body, and prevents the influence on the varistor caused by carbonization of the residual PVA during sintering in the following sintering.
7) Sintering of round blank
And placing the blank body after the binder removal into a crucible paved with a padding material with the same components to prevent the doped element from being impregnated in the sintering process, so that the loss and the uneven distribution of the dopant are avoided. Placing the crucible filled with the blank body into a high-temperature sintering furnace, strictly sealing the furnace door with asbestos, and sintering in an air atmosphere, wherein the specific sintering temperature rise rate, the specific heat preservation time and the specific temperature reduction rate are as follows:
the heating rate is as follows:
the temperature is raised from room temperature to 100 ℃ at a rate of 1 ℃/min
The temperature rise rate is 2 ℃/min at 100 to 1100 DEG C
1100 to 1250 ℃ and the heating rate is 3 ℃/min
1250 to 1350 ℃, and the heating rate is 2 ℃/min
Keeping the temperature at 1350 ℃ for 3h
Cooling rate:
1350-500 deg.C, cooling rate of 5 deg.C/min
Cooling at a rate of 8 deg.C/min from 500 deg.C to room temperature
Finally preparing SnO2A voltage dependent resistor.
For SnO prepared according to the process technology2The piezoresistor is electrically tested. The leakage current is suppressed, and the average value is 4.12A/cm2The mean value of the nonlinear coefficient is 45, the mean value of the voltage-sensitive voltage gradient is 684V/mm, and the withstand surge current density is 5.05KA/cm2。
EXAMPLE III
SnO in this example2The preparation method of the piezoresistor comprises the following steps:
1）SnO2preparation and mixing of main material and dopant
SnO in this practice2The piezoresistor is prepared according to the following proportion: SnO2：97.99%、Co3O4：0.5%、Nb2O5：0.25％、Ta2O5：0.15％、Cr2O3：0.25％、In2O3：0.06％、WO3：0.05%、TiO2: 0.75 percent. Putting the prepared powder into a rubber tank, adding 28mol% of PVA and 600g of deionized water, and uniformly stirring and mixing to prepare first slurry
2) Adding a dispersing agent
Adding 22mol% of dispersing agent and 600g of deionized water into the first slurry prepared in the step 1), and uniformly stirring to obtain a second slurry.
3) Grinding slurry and drying
And (3) putting the second slurry prepared in the step 2) into a planetary ball mill, setting the rotating speed to be 1500 rpm, grinding for 10 hours to enable the particle diameter of the slurry to be less than 1um, then taking out the slurry, putting the slurry into a resistance type air-blast drying box, and setting the constant temperature of 60 ℃ for drying for 10 hours to prepare the moisture-free dry powder.
4) Grinding and granulating of dry powder
Putting the dried powder in the step 3) into a high-frequency grinder for grinding and granulating, wherein the set rotating speed is 550 revolutions per minute, and the time is 6 hours. Repeatedly sieving the ground powder with a sieve of 450 meshes. The particle diameter of the sieved powder is smaller than 1 um.
5) Powder material containing water and tabletting
Spraying 4wt% of deionized water on the powder in the step 4), standing for 8h to enable the powder to fully absorb moisture, and pressing the hydrated powder into a circular blank with the diameter of 5cm by using a forming pressure of 25 Mpa.
6) Glue discharging
Putting the tray for the round blank in the step 5) into a muffle furnace, and discharging glue, wherein the heating rate, the cooling rate and the heat preservation time of the glue discharging are as follows:
the heating rate is as follows:
room temperature to 100 deg.C, 2 deg.C/min
100 to 150 ℃ at 2 ℃/min
150 to 220 ℃ at 1 ℃/min
220 to 300 ℃ at 0.5 ℃/min
300 to 350 ℃, 0.5 ℃/min
350 to 500 ℃, 2 ℃/min
Keeping the temperature at 500 ℃ for 6h
Cooling rate:
500 to 350 ℃, 3 ℃/min
350 to 200 ℃ at 1 ℃/min
200 to 150 ℃ and 0.5 ℃/min
150 ℃ to room temperature, 2 ℃/min
The glue discharging method can completely discharge PVA without influencing the performance of the blank body, and prevents the influence on the varistor caused by carbonization of the residual PVA during sintering in the following sintering.
7) Sintering of round blank
And placing the blank body after the binder removal into a crucible paved with a padding material with the same components to prevent the doped element from being impregnated in the sintering process, so that the loss and the uneven distribution of the dopant are avoided. Placing the crucible filled with the blank body into a high-temperature sintering furnace, strictly sealing the furnace door with asbestos, and sintering in an air atmosphere, wherein the specific sintering temperature rise rate, the specific heat preservation time and the specific temperature reduction rate are as follows:
the heating rate is as follows:
the temperature is raised from room temperature to 100 ℃ at a rate of 1 ℃/min
The temperature rise rate is 2 ℃/min at 100 to 1100 DEG C
1100 to 1250 ℃ and the heating rate is 3 ℃/min
1250 to 1450 ℃, the heating rate is 2 ℃/min
Keeping the temperature at 1450 ℃ for 2h
Cooling rate:
1450 to 500 ℃, and the cooling rate is 5 ℃/min
Cooling at a rate of 8 deg.C/min from 500 deg.C to room temperature
Finally preparing SnO2A voltage dependent resistor.
For SnO prepared according to the process technology2The piezoresistor is electrically tested. The leakage current is suppressed, and the average value is 1.58A/cm2The mean value of the nonlinear coefficient is 52, the mean value of the voltage-sensitive voltage gradient is 733V/mm, and the withstand surge current density is 5.2KA/cm2。
Example four
SnO in this example2The preparation method of the piezoresistor comprises the following steps:
1) SnO = preparation and mixing of main material and dopant
SnO in this practice2The piezoresistor is prepared according to the following proportion: SnO2：98.37%、Co3O=：0.55%、Nb2O5：0.25％、Ta2O5：0.2％、Cr2O3：0.25％、In2O3：0.08％、WO3：0.05%、TiO2: 0.25 percent. Putting the prepared powder into a rubber tank, adding 25mol% of PVA and 550g of deionized water, and uniformly stirring and mixing to prepare first slurry
2) Adding a dispersing agent
Adding 19mol% of dispersing agent and 550g of deionized water into the first solvent prepared in the step 1), and uniformly stirring to obtain second slurry.
3) Grinding slurry and drying
And (3) putting the second slurry prepared in the step 2) into a planetary ball mill, setting the rotating speed to be 1500 rpm, grinding for 10 hours to enable the particle diameter of the slurry to be less than 1um, then taking out the slurry, putting the slurry into a resistance type air-blast drying box, and setting the constant temperature of 60 ℃ for drying for 10 hours to prepare the moisture-free dry powder.
4) Grinding and granulating of dry powder
Putting the dried powder in the step 3) into a high-frequency grinder for grinding and granulating, wherein the set rotating speed is 550 revolutions per minute, and the time is 6 hours. Repeatedly sieving the ground powder with a 400-mesh sieve. The particle diameter of the sieved powder is smaller than 1 um.
5) Powder material containing water and tabletting
Spraying 5wt% of deionized water on the powder in the step 4), standing for 8h to enable the powder to fully absorb moisture, and pressing the hydrated powder into a circular blank with the diameter of 5cm by using a molding pressure of 30 Mpa.
6) Glue discharging
Putting the tray for the round blank in the step 5) into a muffle furnace, and discharging glue, wherein the heating rate, the cooling rate and the heat preservation time of the glue discharging are as follows:
the heating rate is as follows:
room temperature to 100 deg.C, 2 deg.C/min
100 to 150 ℃ at 2 ℃/min
150 to 220 ℃ at 1 ℃/min
220 to 300 ℃ at 0.5 ℃/min
300 to 350 ℃, 0.5 ℃/min
350 to 500 ℃ at 2 ℃/min
Keeping the temperature at 500 ℃ for 6h
Cooling rate:
500 to 350 ℃ at 3 ℃/min
350 to 200 ℃ at 1 ℃/min
200 to 150 ℃ at 0.5 ℃/min
150 to room temperature, 2 ℃/min
The glue discharging method can completely discharge PVA without influencing the performance of the blank body, and prevents the influence on the varistor caused by carbonization of the residual PVA during sintering in the following sintering.
7) Sintering of round blank
And placing the blank body after the binder removal into a crucible paved with a padding material with the same components to prevent the doped element from being impregnated in the sintering process, so that the loss and the uneven distribution of the dopant are avoided. Placing the crucible filled with the blank body into a high-temperature sintering furnace, strictly sealing the furnace door with asbestos, and sintering in an air atmosphere, wherein the specific sintering temperature rise rate, the specific heat preservation time and the specific temperature reduction rate are as follows:
the heating rate is as follows:
the temperature is raised from room temperature to 100 ℃ at a rate of 1 ℃/min
The temperature rise rate is 2 ℃/min at 100 to 1100 DEG C
1100 to 1250 ℃ and the heating rate is 3 ℃/min
1250 to 1300 ℃, and the heating rate is 2 ℃/min
Keeping the temperature at 1300 ℃ for 2h
Cooling rate:
1300 to 500 ℃, and the cooling rate is 5 ℃/min
500 to room temperature, and the cooling rate is 8 ℃/min
Finally preparing SnO2A voltage dependent resistor.
For SnO prepared according to the process technology2The piezoresistor is electrically tested. The leakage current is suppressed, and the average value is 1.12A/cm2The mean value of the nonlinear coefficient is 59, the mean value of the voltage-sensitive voltage gradient is 788V/mm, and the withstand surge current density is 5.5KA/cm2。
The technical solutions described above only represent the preferred technical solutions of the present invention, and some possible modifications to some parts of the technical solutions by those skilled in the art all represent the principles of the present invention, and fall within the protection scope of the present invention.
Claims (8)
1. High-surge-current-tolerance SnO2The method for preparing the varistor ceramic comprises the steps of raw material preparation, dispersion, drying, molding, binder removal and sintering, and is characterized in that titanium ions and tungsten ions are added in the step of raw material preparation, and the too ions are Ta2O5Added in the form of WO3And (4) adding in a form.
2. High inrush current withstanding SnO according to claim 12Varistor ceramicThe method is characterized in that in the step of preparing the raw materials, the molar mass parts of the components are SnO2：97.82～99.05、Co3O4：0.3～0.55、Nb2O5：0.2～0.3、Ta2O5：0.1～0.2、Cr2O3：0.2～0.25、In2O3：0.02～0.08、WO3：0.03～0.05%、TiO2：0 .1～0.75。
3. High inrush current withstanding SnO according to claim 12The method for preparing the varistor ceramic is characterized in that in the step of preparing raw materials, PVA and deionized water are added into the raw materials and stirred uniformly to obtain first slurry.
4. High inrush current resistant SnO according to claim 32The method for preparing the varistor ceramic is characterized in that in the dispersing step, 15-22 mol% of dispersing agent is added into the slurry and stirred, so that the added dispersing agent is uniformly distributed in the mixed solution to obtain second slurry.
5. High surge current tolerant SnO as claimed in claim 42The method for preparing the varistor ceramic is characterized in that in the drying step, the second slurry is put into a planetary ball mill to be ground and mixed for 10 hours at high frequency, so that the particle size of powder in the second mixed solution is less than 1 mu m, and then the second mixed solution is dried for 10 hours at the constant temperature of 60 ℃ to obtain the powder.
6. High inrush current resistant SnO according to claim 52The method for preparing the varistor ceramic is characterized in that in the forming step, the powder is crushed and sieved by a sieve with 300-450 meshes; pressing the sieved powder into a round embryo body with the diameter of 5cm under the pressure of 20-35 MPa.
7. High inrush current resistant SnO according to claim 62Method for preparing varistor ceramicIn the step of discharging the glue, the blank is discharged at the temperature of 100-500 ℃, the temperature is kept for 6h at the glue discharging temperature, and then the blank is cooled to the room temperature, wherein the heating and cooling rates are respectively 30 ℃/h-120 ℃/h and 30 ℃/h-180 ℃/h.
8. High inrush current resistant SnO as claimed in claim 72The method for preparing the varistor ceramic is characterized in that in the sintering step, the blank body after glue discharging is sintered at the temperature of 1300 ℃ and 1450 ℃, the temperature is kept for 2-4h at the sintering temperature, and then the blank body is cooled to the room temperature, wherein the temperature rising and falling rates are respectively 30 ℃/h-120 ℃/h and 300 ℃/h-480 ℃/h.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010193561.3A CN111233461A (en) | 2020-03-18 | 2020-03-18 | High surge current withstanding SnO2Method for preparing varistor ceramic |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010193561.3A CN111233461A (en) | 2020-03-18 | 2020-03-18 | High surge current withstanding SnO2Method for preparing varistor ceramic |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111233461A true CN111233461A (en) | 2020-06-05 |
Family
ID=70868509
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010193561.3A Pending CN111233461A (en) | 2020-03-18 | 2020-03-18 | High surge current withstanding SnO2Method for preparing varistor ceramic |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111233461A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114230333A (en) * | 2021-12-24 | 2022-03-25 | 国网浙江省电力有限公司瑞安市供电公司 | Preparation of high-performance SnO2Method for voltage dependent resistor |
| CN115974544A (en) * | 2022-12-28 | 2023-04-18 | 安徽工程大学 | In and Ta co-doped zinc oxide composite functional ceramic, preparation method and application thereof |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4333861A (en) * | 1976-11-26 | 1982-06-08 | Matsushita Electric Industrial Co., Ltd. | Thick film varistor |
| CN101197203A (en) * | 2007-11-30 | 2008-06-11 | 华南理工大学 | Tin oxide piezoresistance material and method for producing the same |
-
2020
- 2020-03-18 CN CN202010193561.3A patent/CN111233461A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4333861A (en) * | 1976-11-26 | 1982-06-08 | Matsushita Electric Industrial Co., Ltd. | Thick film varistor |
| CN101197203A (en) * | 2007-11-30 | 2008-06-11 | 华南理工大学 | Tin oxide piezoresistance material and method for producing the same |
Non-Patent Citations (2)
| Title |
|---|
| M.A.L. MARGIONTE ET AL.: "Nonlinear characteristics of Cr2O3, WO3, ZnO and CoO doped SnO2 varistors", 《MATERIALS LETTERS》 * |
| ZHIJIAN PENG ET AL.: ""Microstructure and nonohmic properties of SnO2–Ta2O5–TiO2 varistor system doped with CuO", 《INTERNATIONAL JOURNAL OF MODERN PHYSICS B》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114230333A (en) * | 2021-12-24 | 2022-03-25 | 国网浙江省电力有限公司瑞安市供电公司 | Preparation of high-performance SnO2Method for voltage dependent resistor |
| CN115974544A (en) * | 2022-12-28 | 2023-04-18 | 安徽工程大学 | In and Ta co-doped zinc oxide composite functional ceramic, preparation method and application thereof |
| CN115974544B (en) * | 2022-12-28 | 2023-11-24 | 安徽工程大学 | In and Ta co-doped zinc oxide composite functional ceramic, preparation method and application thereof |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101383208B (en) | Preparation of high voltage gradient zinc oxide varistor valve | |
| CN111233461A (en) | High surge current withstanding SnO2Method for preparing varistor ceramic | |
| CN100485827C (en) | Method for preparing high-potential gradient zinc oxide piezoresistance by low-temperature sintering | |
| JP2001516142A (en) | Nanocrystallite powder based varistor formed by mechanical grinding | |
| CN102424576B (en) | Preparation method of non-linear composite material having adaptive uniform electric field | |
| CN102515741A (en) | Zinc oxide varistor material and preparation method thereof | |
| US8535575B2 (en) | Current-voltage non-linear resistor and method of manufacture thereof | |
| CN108546111A (en) | A kind of zinc oxide piezoresistor ceramic and preparation method thereof of high-voltage gradient, low residual voltage, low Leakage Current | |
| KR102120577B1 (en) | Ceramic material, varistor, ceramic material and method of manufacturing varistor | |
| EP1798741A1 (en) | Current/voltage nonlinear resistor | |
| CN101333104A (en) | Zinc oxide voltage-sensitive ceramic materials doped by superplasticity nanometer oxide and preparation method | |
| CN105884345A (en) | High-voltage-gradient, low-residual-voltage and low-leakage-current ceramic and preparing method thereof | |
| CN109704752B (en) | SnO (stannic oxide)2Piezoresistor and preparation method thereof | |
| CN109678490A (en) | A kind of doping boron and the direct current ZnO varistor of ruthenium ion and preparation method thereof | |
| CN101279843B (en) | Superplastic zinc oxide pressure-sensitive ceramic material and preparation thereof | |
| CN110423110B (en) | Ultrahigh nonlinear ZnO-Bi2O3Base pressure sensitive ceramic and preparation method thereof | |
| CN114597010B (en) | Production process of high-performance zinc oxide resistance card | |
| CN107459347B (en) | Lead-free ceramic material with high energy storage density and high energy storage efficiency and preparation method thereof | |
| CN111362689B (en) | Method for improving zinc oxide piezoresistor through regulating bismuth oxide crystal form, zinc oxide resistor disc and preparation method thereof | |
| CN105565801A (en) | Preparation method of high-gradient and large-discharge-current-capacity voltage-sensitive ceramics for ultra-high-voltage power transmission system | |
| CN115745596B (en) | Zinc oxide-based resistor disc composition, zinc oxide-based resistor disc, and preparation method and application thereof | |
| WO2020019274A1 (en) | Method for optimizing zinc oxide varistor | |
| JP7359329B1 (en) | Antimony oxide substitute zinc oxide element | |
| KR101166047B1 (en) | ZnO-BASED VARISTOR COMPOSITION | |
| CN114230333A (en) | Preparation of high-performance SnO2Method for voltage dependent resistor |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WD01 | Invention patent application deemed withdrawn after publication | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20200605 |