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Hydrothermal reaction method for manufacturing negative temperature coefficient heat-sensitive powder

A technology of negative temperature coefficient and hydrothermal reaction, applied in the direction of resistors with negative temperature coefficient, etc., can solve the problems of long synthesis cycle, difficult to control reaction conditions, high temperature, etc., achieve short synthesis cycle, easy control of reaction conditions, and high production efficiency high rate effect

Inactive Publication Date: 2008-12-10
CHINA JILIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] The preparation methods of negative temperature coefficient heat-sensitive powder usually adopt ball milling method, co-precipitation method, sol-gel method, etc., but these methods have difficulties such as high reaction temperature, long synthesis cycle, and difficult control of reaction conditions.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0008] Embodiment 1 (content is in mole)

[0009] First weigh 3.6mol of manganese acetate and 2.4mol of nickel acetate and dissolve them in deionized water, stir fully, add equimolar ammonia solution in the stirred reaction solution, and adjust the pH value of the reaction solution to 10.0; then the reaction solution All were transferred into a 5L autoclave for hydrothermal reaction. The rotation speed of the autoclave was set at 600 rpm, the reaction temperature was 220° C., and the reaction was carried out for 10 hours. After the reaction is completed, pass circulating water to cool the product to room temperature, take out the reactant with a vacuum pump, wash with deionized water and absolute ethanol for 3-4 times, then centrifuge, wash, and dry at 60°C. Sensitive nano powder.

[0010] Then put the negative temperature coefficient heat-sensitive nano powder into the muffle furnace and thermally decompose it at 700-900°C for 2-8 hours for heat treatment. After fully grindi...

Embodiment 2

[0011] Embodiment 2 (content is in mole)

[0012] First weigh 3.7mol of manganese sulfate, 2.4mol of nickel sulfate, and 0.6mol of cobalt sulfate and dissolve them in deionized water, stir fully, add equimolar ammonia solution to the stirred reaction solution, and adjust the pH value of the reaction solution to 9.5 Then all the reaction solution was moved into a 5L autoclave for hydrothermal reaction, the speed of the autoclave was set at 600 rpm, the reaction temperature was 240°C, and the reaction was carried out for 8 hours. After the reaction is completed, feed circulating water to cool the product to room temperature, extract the reactant with a vacuum pump, wash with deionized water and absolute ethanol for 3-4 times, then centrifuge, wash, and dry at 80°C. Sensitive nano powder.

[0013] Then put the negative temperature coefficient heat-sensitive nano powder into the muffle furnace and thermally decompose it at 700-900°C for 2-8 hours for heat treatment. After fully g...

Embodiment 3

[0014] Embodiment 3 (content is in mole)

[0015] First weigh 3.0mol of manganese nitrate, 2.0mol of nickel nitrate, and 1.0mol of cobalt nitrate and dissolve them in deionized water, stir thoroughly, add an equimolar amount of ammonia solution to the stirred reaction solution, and adjust the pH of the reaction solution to 9.0 Then all the reaction solution was moved into a 5L autoclave for hydrothermal reaction, the speed of the autoclave was set at 600 rpm, the reaction temperature was 250°C, and the reaction was carried out for 8 hours. After the reaction is completed, feed circulating water to cool the product to room temperature, extract the reactant with a vacuum pump, wash with deionized water and absolute ethanol for 3-4 times, then centrifuge, wash, and dry at 80°C. Sensitive nano powder.

[0016] Then put the negative temperature coefficient heat-sensitive nano powder into the muffle furnace and thermally decompose it at 700-900°C for 2-8 hours for heat treatment. A...

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Abstract

The invention relates to a method for preparing negative temperature coefficient heat-variable powder body-the method of hydro-thermal chemical reaction. De-ionized water is added into reaction raw materials of manganous salt, nickelous salt, cobaltous salt and magnesium salt, the mixture is stirred sufficiently; an ammonia solution is added into the stirred reaction solution until the pH value of the reaction solution is between 8.0 and 12.0; the reaction solution is put inside a high pressure reaction kettle to perform the hydro-thermal reaction and then is subject to washing and baking so that the negative temperature coefficient heat-variable nano powder material is produced; the negative temperature coefficient heat-variable nano powder material is put into a blind roaster to be pyrolyzed at a temperature of between 600 and 900 DEG C for 2 to 8 hours, and the negative temperature coefficient heat-variable powder material is produced after sufficient grinding process. Compared with the ball milling method, the coprecipitation method and the sol-gel method, the method has the characteristics that the chemical compositions are even, the reaction temperature is low, the productivity is high, the synthesizing cycle is short, the reaction condition is controlled easily, and the inevitable agglomeration phenomenon in the sintering process is reduced, etc.

Description

technical field [0001] The invention relates to a preparation method of a negative temperature coefficient heat-sensitive powder-a method of hydrothermal chemical reaction. Background technique [0002] The preparation methods of negative temperature coefficient heat-sensitive powder usually adopt ball milling method, co-precipitation method, sol-gel method, etc., but these methods have difficulties such as high reaction temperature, long synthesis period, and difficult control of reaction conditions. Aiming at the existing problems, the present invention develops a hydrothermal chemical reaction method for the preparation of negative temperature coefficient heat-sensitive powder through a large number of experiments. Contents of the invention [0003] The purpose of the present invention is to develop the preparation method of the negative temperature coefficient heat-sensitive powder - the hydrothermal reaction method, adding the reaction raw materials of divalent mangan...

Claims

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Application Information

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IPC IPC(8): C04B35/36C04B35/622H01C7/04
Inventor 王疆瑛
Owner CHINA JILIANG UNIV
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