A process for preparing low residual voltage zno varistor ceramics

A technology of varistor and process method, applied in the direction of varistor, varistor core, etc., can solve the problem of increasing leakage current density, can not meet industrial applications, etc., to suppress the increase of leakage current, suitable for industrial applications Applications, high-performance effects

Active Publication Date: 2012-02-22
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 20μA / cm 2 Above, the nonlinear coefficient drops below 30, which can no longer meet the needs of industrial applications

Method used

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  • A process for preparing low residual voltage zno varistor ceramics
  • A process for preparing low residual voltage zno varistor ceramics

Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0017] The preparation method of the present invention is characterized in that the method is based on the preparation technology of low residual voltage ZnO varistor ceramics based on the two-step sintering method and the seed crystal method, and the raw material formula of the preparation method includes: ZnO (92.7-97mol%) 、 Bi 2 o 3 (0.4-0.9mol%), MnO 2 (0.4-0.7mol%), Sb 2 o 3 (0.5-1.5mol%), Co 2 o 3 (0.5-1.5mol%), SiO 2 (0.8-1.7mol%), Al(NO 3 ) 3 9H 2 O (0.1-0.4mol%) and Cr 2 o 3 (0.3-0.7mol%); the method comprises the following steps:

[0018] 1) Preparation of the seed crystal and the first step of sintering:

[0019] (11) Using 20%-50% of ZnO and 0%-20% of Bi in the raw material formula 2 o 3 and all Al(NO 3 ) 3 9H 2 O; be placed in a ball mill tank with deionized water or alcohol added, ball milled for 8-12 hours, and then dried as a seed crystal raw material;

[0020] (12) Put the dried seed crystal raw material into a high-temperature electric furna...

Embodiment 1

[0027] The raw material formula of the present embodiment is as follows:

[0028] The low residual voltage ZnO varistor ceramic raw material is prepared according to the following ratio: ZnO (94.8mol%), Bi 2 o 3 (0.7mol%), MnO 2 (0.5mol%), Sb 2 o 3 (1mol%), Co 2 o 3 (1mol%), SiO 2 (1.25mol%), Al(NO 3 ) 3 9H 2 O (0.25mol%) and Cr 2 o 3 (0.5mol%); The method of the present embodiment comprises the following steps:

[0029] 1) Preparation of the seed crystal and the first step of sintering:

[0030] (11) Adopt 25% ZnO and all Al(NO 3 ) 3 9H 2 0; be placed in the ball mill tank that adds deionized water for 10 hours, and then dry as the seed crystal raw material;

[0031] (12) Put the dried seed crystal raw material into a high-temperature electric furnace, pre-burn 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;

[0032] (13) After pulverizing the sintered hard block of seed crystal,...

Embodiment 2

[0044] The raw material formula of the present embodiment is as follows:

[0045] The low residual voltage ZnO varistor ceramic raw material is prepared according to the following ratio: ZnO (92.7mol%), Bi 2 o 3 (0.9mol%), MnO 2 (0.7mol%), Sb 2 o 3 (1.5mol%), Co 2 o 3 (1.5mol%), SiO 2 (1.7mol%), Al(NO 3 ) 3 9H 2 O (0.4mol%) and Cr 2 o 3 (0.7mol%); The method of the present embodiment comprises the following steps:

[0046] 1) Preparation of the seed crystal and the first step of sintering:

[0047] (11) Using 25% ZnO and 25% Bi in the raw material formula 2 o 3 and all Al(NO 3 ) 3 9H 2 0; be placed in the ball mill tank that adds deionized water for 12 hours, and then dry as the seed crystal raw material;

[0048] (12) Put the dried seed crystal raw material into a high-temperature electric furnace, pre-fire the first step at 1300° C. for 6 hours to form a hard block of seed crystal, and cool to normal temperature with the furnace;

[0049] (13) After pulver...

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Abstract

The invention relates to a process method for preparing low-residual-voltage ZnO varistor ceramics, belonging to the technical field of processing of low-residual-voltage ZnO varistor ceramics; The preparation process of resistance ceramics, the raw material formula includes: ZnO, Bi2O3, MnO2, Sb2O3, Co2O3, SiO2, Al(NO3)3·9H2O and Cr2O3; the method includes: using ZnO, Bi2O3 and Al(NO3) in the raw material formula 3·9H2O; ball-milled and dried as a seed crystal raw material; then put into a high-temperature electric furnace, the first step is pre-sintered into seed crystal hard blocks, and cooled to room temperature with the furnace; after ball-milling, sieved to obtain seed crystals; The remaining raw materials and seed crystals are mixed with PVA solution, ball-milled, dried, sieved, granulated with water, and pressed into a green body; the green body is sintered in the second step and then cooled to room temperature. The invention reduces the resistivity of crystal grains and the residual voltage of the ZnO varistor, and at the same time suppresses the increase of leakage current and the decrease of nonlinear coefficient. Thus, the material has higher performance and is more suitable for industrial application.

Description

technical field [0001] The invention belongs to the technical field of processing low residual voltage ZnO varistor ceramics, and in particular relates to a new two-step sintering seed crystal method preparation and sintering ceramic technology. Background technique [0002] The ZnO varistor is made of ZnO as the main raw material, and a small amount of Bi is added. 2 o 3 , MnO 2 , Sb 2 o 3 、Co 2 o 3 , SiO 2 and Cr 2 o 3 etc., 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. ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01C7/112
Inventor 何金良龙望成胡军曾嵘陈水明
Owner TSINGHUA UNIV
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