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Process method for preparing low residual voltage ZnO varistor ceramic

The technology of a varistor and a process method is applied in the processing field of low-residual-voltage ZnO varistor ceramics, which can solve the problems of inability to meet industrial applications, increase in leakage current density, etc., so as to be suitable for industrial applications and suppress the growth of leakage current. , high-performance effects

Active Publication Date: 2010-07-28
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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  • Process method for preparing low residual voltage ZnO varistor ceramic
  • Process method for preparing low residual voltage ZnO varistor ceramic

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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 ceramic and belongs to the technical field of residual voltage ZnO varistor ceramic machining; the residual voltage ZnO varistor ceramic preparation process is based on the sintering process and seeded solution growth and includes the raw materials of ZnO, Bi2O3, MnO2, Sb2O3, Co2O3, SiO2, Al (NO3) 3 9H2O and Cr2O3; the preparation method includes that: ZnO, Bi2O3 and Al (NO3) 3 9H2O in the raw material formula are adopted to be ground by a ball mill and dried as seed crystal raw material; the seed crystal raw material is placed in a high temperature electric resistance furnace for pre-sintering to from seed crystal lumps as the first step, and the seed crystal lumps are cooled to normal temperature in the furnace; and then the seed crystal lumps are ground by the ball mill again and sieved to obtain seed crystals; all remaining raw materials, the seed crystals and PVA solution are mixed and ground by the ball mill to be dried, sieved and granulated with water content and pressed into blanks; and the blanks are sintered and cooled to normal temperature in the second step. The process method not only can reduce grain resistivity and ZnO varistor residual voltage, but also restrains the increasing of current leakage and the decreasing of non-linear coefficient. The low residual voltage ZnO varistor ceramic 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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IPC IPC(8): C04B35/453C04B35/622
Inventor 何金良龙望成胡军曾嵘陈水明
Owner TSINGHUA UNIV
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