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Making method of low-residual voltage piezoresistor of low-resistivity ZnO crystal grains

A low-resistivity, varistor technology, applied in the field of varistor ceramic preparation with reduced ZnO grain resistivity, can solve the problems of inability to meet industrial applications, the nonlinear coefficient drops below 30, the leakage current density increases, etc. Suitable for industrial applications, the effect of suppressing the decrease of the nonlinear coefficient and suppressing the increase of the leakage current

Inactive Publication Date: 2016-08-10
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When the addition of Al ions reaches 0.05mol%, the leakage current density will increase to more than 20μA / cm2, and the nonlinear coefficient will drop below 30, which cannot meet the needs of industrial applications.

Method used

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preparation example Construction

[0028] A method for preparing varistor ceramics that reduces the resistivity of ZnO grains, the preparation raw materials include zinc oxide ZnO, bismuth oxide Bi2O3, antimony trioxide Sb2O3, manganese dioxide MnO2, chromium oxide Cr2O3, cobalt trioxide Co2O3, Silicon SiO2, indium nitrate crystal In(NO3)3·9H2O, the preparation steps include a rough seed crystal step, a primary sintering step, a seed crystal refining step, a raw material mixing step, and a secondary sintering step.

[0029] In the step of preparing the seed crystal, the raw material for preparing the seed crystal and the mass fraction ratio thereof are ZnO: Bi2O3: In(NO3) 3 = 20-50: 0.01-0.18: 0.1-0.4, and the roughing method of the seed crystal is:

[0030] The above-mentioned raw materials for preparing seed crystals were added to deionized water and alcohol, and ball milled for 8-12 hours to form a seed crystal suspension.

[0031] The seed crystal suspension is dried to prepare the seed crystal raw material...

Embodiment 1

[0050] The raw material formula of the present embodiment is as follows:

[0051] This low residual voltage ZnO varistor ceramic raw material is prepared according to the following ratio: ZnO (94.8mol%), Bi2O3 (0.7mol%), MnO2 (0.5mol%), Sb2O3 (1mol%), Co2O3 (1mol%), SiO2 ( 1.25mol%), In(NO3) 9H2O (0.25mol%) and Cr2O3 (0.5mol%); the method of the present embodiment comprises the following steps:

[0052] Preparation of the seed crystal and the first step of sintering:

[0053] Use 25% ZnO and all In(NO3)3.9H2O in the raw material formula; place it in a ball mill tank with deionized water and mill it for 10 hours, then dry it as the seed crystal raw material;

[0054] Put the dried seed crystal raw material into a high-temperature electric furnace, and pre-fire it at 1300°C for 4 hours in the first step to form a hard block of seed crystal, and cool it to room temperature with the furnace;

[0055] After crushing the sintered hard block of seed crystals, put them in a ball mill ...

Embodiment 2

[0067] The raw material formula of the present embodiment is as follows:

[0068] This low residual voltage ZnO varistor ceramic raw material is prepared according to the following ratio: ZnO (92.7mol%), Bi2O3 (0.9mol%), MnO2 (0.7mol%), Sb2O3 (1.5mol%), Co2O3 (1.5mol%), SiO2(1.7mol%), In(NO3)3.9H2O(0.4mol%) and Cr2O3(0.7mol%); The method of the present embodiment comprises the following steps:

[0069] Preparation of the seed crystal and the first step of sintering:

[0070] Adopt 25% ZnO, 25% Bi2O3 and all In(NO3)3.9H2O in the raw material formula; place it in a ball mill jar with deionized water and mill it for 12 hours, then dry it as the seed crystal raw material;

[0071] Put the ball-milled and dried seed crystal raw materials into a high-temperature electric furnace, pre-fire the first step at 1300°C for 6 hours to form a hard block of seed crystals, and cool to room temperature with the furnace;

[0072] After crushing the sintered hard block of seed crystals, place ...

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Abstract

A making method of a low-residual voltage piezoresistor of low-resistivity ZnO crystal grains is characterized in that raw materials for making the low-residual voltage piezoresistor include zinc oxide (ZnO), bismuth oxide (Bi2O3), diantimony trioxide (Sb2O3), manganese dioxide (MnO2), chromium oxide (Cr2O3), cobalt sesquioxide (Co2O3), silica (SiO2), aluminum nitrate crystals (Al(NO3)3.9H2O) and gallium nitrate (Ga(NO3)3.9H2O); and the making method comprises the steps of crude seed crystal preparation, primary sintering, seed crystal refinement, raw material and secondary sintering. The method has the following advantages: the structure components and the structure change of the above material in the preparation method can be artificially controlled through strictly changing the sintering process flow and controlling process parameters, so the resistivity of the grains is reduced, the residual voltage of the ZnO piezoresistor is reduced, and increase of the leakage current and decrease of a nonlinear coefficient are inhibited, thereby the material has high performances and is suitable for industrial applications.

Description

technical field [0001] The invention relates to the field of material preparation, in particular to a method for preparing varistor ceramics for reducing the resistivity of ZnO grains. Background technique [0002] ZnO varistors are made of ZnO as the main raw material, adding a small amount of Bi2O3, MnO2, Sb2O3, Co2O3, SiO2 and Cr2O3, etc., and are prepared by ceramic sintering process. Due to its good nonlinear performance and the advantages of large current capacity, since it was discovered in the 1870s, ZnO varistors have been widely used in power system lightning protection and power equipment protection as the core component of power system lightning arresters. As we all know, the insulation cost accounts for the main part of the power engineering cost. With the increase of the voltage level of the power system, the insulation consumption at the high voltage level is even greater. The insulation level of the power system is based on the residual voltage protection le...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/453C04B35/64
CPCC04B35/453C04B35/64C04B2235/3241C04B2235/3267C04B2235/3275C04B2235/3286C04B2235/3294C04B2235/3298C04B2235/3418
Inventor 何金良胡军孟鹏飞
Owner TSINGHUA UNIV
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