Varistor ceramic preparation method reducing ZnO grain resistivity

A technology of grain resistivity and varistor, which is applied in the field of preparation of varistor ceramics with reduced ZnO grain resistivity, can solve problems such as the non-linear coefficient drops below 30, cannot meet industrial applications, and the leakage current density increases. , to achieve the effect of suppressing the decline of nonlinear coefficient, suitable for industrial applications, and suppressing the increase of leakage current

Inactive Publication Date: 2016-08-17
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/c

Method used

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Example Embodiment

[0026] A method for preparing varistor ceramics for reducing the resistivity of ZnO crystal grains. The preparation raw materials include zinc oxide ZnO and bismuth oxide Bi 2 O 3 , Antimony Trioxide Sb 2 O 3 , Manganese Dioxide MnO 2 , Chromium oxide Cr 2 O 3 , Cobalt trioxide Co 2 O 3 , Silica SiO 2 , Indium nitrate crystal In(NO 3 ) 3 ·9H 2 O, the preparation steps include a coarse seed crystal step, a primary sintering step, a seed crystal refinement step, a raw material mixing step, and a secondary sintering step.

[0027] In the seed crystal preparation step, the seed crystal preparation raw material and its preparation mass fraction ratio are ZnO: Bi 2 O 3 : In(NO 3 ) 3 = 20-50: 0.01-0.18: 0.1-0.4, the step method of seed crystal coarsening is:

[0028] Add the above-mentioned raw materials for preparing seed crystals into deionized water and alcohol and then ball mill for 8-12 hours to form a seed crystal suspension.

[0029] The seed crystal suspension is dried to prepare see...

Example Embodiment

[0047] Example one

[0048] The raw material formula of this embodiment is as follows:

[0049] The low residual voltage ZnO varistor ceramic raw materials are prepared according to the following proportions: 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%), In(NO 3 ) 3 ·9H 2 O(0.25mol%) and Cr 2 O 3 (0.5mol%);

[0050] The method of this embodiment includes the following steps:

[0051] Preparation of seed crystal and first sintering:

[0052] Using 25% ZnO and all In(NO 3 ) 3 ·9H 2 O; Ball milled in a ball mill tank with deionized water for 10 hours, and then dried as a seed crystal raw material;

[0053] Put the ball-milled and dried seed crystal material into a high-temperature electric furnace, pre-burn it at 1300℃ for 4 hours to form a hard seed crystal, and then cool it to room temperature with the furnace;

[0054] After crushing the sintered hard seed crystals, place them in a ball milling tank with deionized water or alcoh...

Example Embodiment

[0065] Example two

[0066] The raw material formula of this embodiment is as follows:

[0067] The low residual voltage ZnO varistor ceramic raw materials are prepared according to the following proportions: 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%), In(NO 3 ) 3 ·9H 2 O(0.4mol%) and Cr 2 O 3 (0.7mol%); the method of this embodiment includes the following steps:

[0068] Preparation of seed crystal and first sintering:

[0069] Using 25% ZnO and 25% Bi in the raw material formula 2 O 3 And all In(NO 3 ) 3 ·9H 2 O; Ball milled in a ball mill tank with deionized water for 12 hours, and then dried as a seed crystal raw material;

[0070] Put the ball-milled and dried seed crystal material into a high-temperature electric furnace, and pre-burn the seed crystal in the first step at 1300°C for 6 hours to form a hard seed crystal, and then cool to room temperature with the furnace;

[0071] After crushing the sintered hard seed ...

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Abstract

The invention discloses a varistor ceramic preparation method reducing ZnO grain resistivity. The preparation raw materials include zinc oxide ZnO, bismuth oxide Bi2O3, antimonous oxide Sb2O3, manganese dioxide MnO2, chromium oxide Cr2O3, cobalt oxide Co2O3, silicon dioxide SiO2 and indium nitrate crystal In(NO3)3.9H2O; and the preparation steps include a step of seed crystal roughing, a step of primary sintering, a step of seed crystal refinement, a step of raw material mixing and a step of secondary sintering. The method has the following beneficial effects: by strictly changing the control technology flow and the control technology parameters, the structural components and structural change of the material in the preparation process can be manually controlled, the grain resistivity and the residual voltage of ZnO varistor are reduced while the increase of leakage current and the decrease of nonlinear coefficient are inhibited, and thus the material has higher performance and is more suitable for industrial application.

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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IPC IPC(8): C04B35/453C04B35/64
CPCC04B35/453C04B35/64C04B2235/3241C04B2235/3267C04B2235/3275C04B2235/3294C04B2235/3298C04B2235/3418C04B2235/656
Inventor 胡军何金良孟鹏飞
Owner TSINGHUA UNIV
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