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Zinc oxide piezoresistor material and preparation method

A varistor, zinc oxide technology, applied in varistors, varistor cores, etc., can solve problems such as high cost, limited sintering temperature, and high cost

Inactive Publication Date: 2013-04-10
SHENZHEN SUNLORD ELECTRONICS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The general sintering temperature of zinc oxide varistor ceramics is 1100-1500°C, while chip varistors are limited in their sintering temperature due to the addition of internal electrodes inside the ceramic body.
The internal electrode metals generally used are platinum, palladium, silver-palladium alloy or pure silver. Among them, palladium and platinum are extremely expensive. Using these two metals as internal electrodes will lead to a substantial increase in the cost of the varistor, which is not suitable for industrial production. Pure silver Low sintering temperature (below 950°C) is not conducive to the sintering of zinc oxide ceramics. Therefore, silver-palladium alloys are used as internal electrodes in the current chip varistor industry, and the sintering of zinc oxide varistor ceramics is reduced by improving the formula and process of zinc oxide varistors. temperature, the sintering temperature of the existing zinc oxide varistor material can be reduced to 1020~1100°C, so that the chip varistor can use an alloy with a silver-palladium mass ratio of 6 / 4 or 7 / 3 as the internal electrode, but the cost still higher

Method used

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Examples

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preparation example Construction

[0052] The present invention also provides a method for preparing the aforementioned zinc oxide varistor material, in one embodiment, comprising the following steps:

[0053] 1) Mix the additives in the solvent according to the ratio and perform ball milling to make them fully mixed. The solvent is propyl acetate and ethanol with a mass ratio of 7.5:2.5, and the mass ratio of zirconia balls, additives, and solvent is 8: 1:3;

[0054] 2) Sand-mill the solution from which the zirconia balls have been filtered, so that the particle size of the additive is ground to D50=0.35-0.45 μm, forming a slurry with uniformly dispersed particle size;

[0055] 3) Add the solvent, dispersant and main material zinc oxide described in step 1) to the slurry obtained in step 2), the dispersant is 0.5%~3% of the mass of zinc oxide, and continue to disperse by sand milling, so that The particle size of the powder is uniformly ground, so that the particle size is D50=0.20-0.30 μm, and the zinc oxide...

Embodiment 1

[0059] The zinc oxide varistor material includes main materials and additives with the following molar percentages: main material ZnO 95.17%, additive: Bi 2 o 3 0.5%, Cr 2 o 3 0.5%, TiO 2 0.5%, MnCO 3 1%, BaCO 3 0.2%, Co 3 o 4 0.8%, Ni 2 o 3 0.3%, SnO 2 0.5%, SrCO 3 0.2%, V 2 o 5 0.6%, H 3 BO 3 0.2%, Al 2 (NO 3 ) 3 ?9H 2 O 0.03%. Its preparation method is as follows:

[0060] Weigh all kinds of powders according to the above molar ratio, firstly mix the additive with solvent, then add zirconia balls, additives and solvent into the ball mill tank respectively (propyl acetate / ethanol mass ratio=7.5 / 2.5), zirconia balls: The mass ratio of additives and solvents is 8:1:3, ball milling on a planetary ball mill for 1-2 hours at a rotation speed of 200-400rmp, so that the additives are fully mixed evenly;

[0061] After the premixed ball milling of the above additives is completed, pour the solution filtered out of the zirconia balls into the sto...

Embodiment 2

[0067] The zinc oxide varistor material includes main materials and additives with the following molar percentages: main material ZnO 95.39%, additive: Bi 2 o 3 0.8%, Cr 2 o 3 0.2%, TiO 2 0.8%, MnCO 3 0.6%, BaCO 3 0.2%, Co 3 o 4 0.5%, Ni 2 o 3 0.3%, SnO 2 0.3%, SrCO 3 0.2%, V 2 o 5 0.6%, H 3 BO 3 0.1%, Al 2 (NO 3 ) 3 ?9H 2 O 0.01%.

[0068] The zinc oxide varistor material and the chip zinc oxide varistor were produced according to the ratio of this embodiment. The preparation process was the same as in Example 1. The chip zinc oxide varistor produced in this embodiment was tested, and the potential gradient was 310V / mm, nonlinear coefficient average 23.4, leakage current (0.75V1mA) 2.8μA, withstand 8 / 20μs impact current density: 12.2A / mm 2 , other mechanical and reliability performance is excellent.

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Abstract

The invention discloses a zinc oxide piezoresistor material which comprises a main material and an additive, wherein the main material comprises 92-97mol% of ZnO; and the additive comprises 0.5-1.5mol% of Bi2O3, 0.1-1.2mol% of Cr2O3, 0.1-1.5mol% of MnCO3, 0.1-1.0mol% of BaCO3, 0.1-1.5mol% of Co3O4, 0.1-1.2mol% of SnO2, 0.1-1.0mol% of SrCO3, 0.1-1.0mol% of V2O5, 0.1-1mol% of H3BO3, and 0.005-0.1mol% of Al2(NO3)3.9H2O. When the zinc oxide piezoresistor material is adopted for preparing a finished product, the sintering temperature can be reduced to 900-940 DEG C while various excellent properties are ensured; when the zinc oxide piezoresistor material is adopted for preparing a sheet zinc oxide piezoresistor, a silver palladium alloy with a silver mass fraction greater than or equal to 85% can be matched as an inner electrode or pure silver can serve as the inner electrode; and the cost is lowered greatly.

Description

technical field [0001] The invention relates to the field of varistor material manufacturing, in particular to a zinc oxide varistor material and a preparation method. Background technique [0002] ZnO varistor is based on ZnO powder, adding various traces of other metal compound additives (such as Bi 2 o 3 , Sb 2 o 3 , MnCO 3 、Co 2 o 3 、Cr 2 o 3 etc.), a polycrystalline multi-phase semiconductor ceramic component formed by mixing, molding and sintering at high temperature. Since its invention, ZnO varistors have been widely used in power systems and electronics industries due to their low cost, convenient manufacture, large nonlinear coefficient, fast response time, and large flow capacity. [0003] The general sintering temperature of zinc oxide varistor ceramics is 1100-1500°C, while chip varistors are limited in their sintering temperature due to the addition of internal electrodes inside the ceramic body. The internal electrode metals generally used are platin...

Claims

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Application Information

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IPC IPC(8): C04B35/453C04B35/622H01C7/112
Inventor 冯志刚毛海波贾广平杜士雄
Owner SHENZHEN SUNLORD ELECTRONICS
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