CN1296945C - Method of using acetate to prepare heat sensitire resistance oxide nano-powder - Google Patents

Abstract

The present invention relates to a method of using acetate to prepare heat sensitive resistance oxide nano-powder. The method takes Co, Mn and Ni as raw materials of acetates, oxalic acid is used as a precipitating agent, and finally, mixing heat resistance oxide nano-powder of the acetates of Co, Mn and Ni can be prepared through the processes of mixing, coprecipitation, washing, distributed processing, drying and calcining. Granular size of the powder is usually in a range of 50 to 150 nm. The powder prepared by the method is a high-performance NTC heat sensitive resistor with the advantages of high resistance value consistency, high B value consistency and good interchanging performance.

Description

Method for preparing thermistor oxide nanopowder with acetate

Technical field

The invention relates to a method for preparing NTC thermistor oxide nanopowder with acetate.

Background technique

The co-precipitation method refers to the method of adding a precipitating agent to a mixed solution containing various metal ion salts, so that all ions can be precipitated together, and a uniform precipitation can be obtained. It is an important method for preparing composite oxides containing two or more metal elements. At present, the co-precipitation method is widely used to prepare ultra-fine powder or nano-powder materials of functional ceramics such as sensitive materials, ferrite, and fluorescent materials. Based on the liquid-phase co-precipitation technology, the present invention finds out a method for preparing thermistor oxide nanopowder by using acetate through comprehensive analysis and comparison of many preparation methods.

Contents of the invention

The purpose of the invention is to study a method for preparing thermistor oxide nanopowder with acetate. This method uses Co, Mn, Ni acetate as raw materials, oxalic acid as precipitating agent, and finally prepares thermistor nanopowder through stirring, co-precipitation, washing, dispersion treatment, drying, calcination and other processes. The particle size of the powder is generally in the range of 50-150nm. If soft agglomeration occurs, the size of the agglomerated particles generally ranges from 0.1-4μm. The powder is a spinel structure phase.

The general traditional process of preparing the oxide powder of thermistor is mechanical grinding method. The powder components prepared by this method are not easy to mix to achieve a very uniform. The resistance value consistency and B value consistency of the thermistor element are relatively good. Difference. The preparation of oxide powder by liquid phase co-precipitation method has the advantages of uniform mixing of components, controllable purity and particle size, and finer powder particle size, which can realize uniform mixing of particles at the atomic and molecular levels. The preparation process is relatively simple and requires less equipment. , low cost, and the prepared NTC thermistor can have higher resistance value consistency and B value consistency, better interchangeability, etc., so it has good practical value and application prospect.

The method for preparing thermistor oxide nanopowder with acetate of the present invention is carried out as follows:

a. First, take the acetates of Co, Mn, and Ni respectively as raw materials, the ratio of which is: Co: Mn: Ni=30-65: 20-40: 10-30, mix and dissolve in deionized water to control the metal ions The molar concentration of acetate is 0.05-0.4mol/L, configured as a mixed solution of main components;

b. Use oxalic acid as a precipitant, configure it into a precipitant solution, weigh the analytically pure oxalic acid with a molar ratio of 1-2.0:1 to the metal ion acetate, dissolve it in deionized water, fully stir and dissolve, and control the molar concentration to 0.05 -0.2mol/L;

c. Slowly pour the mixed solution of Co, Mn and Ni acetate into the oxalic acid precipitant solution for co-precipitation reaction. The temperature is 10°C-80°C. Stir continuously while reacting, and control the pH value at 5 with ammonia water -6;

d. Leave the reacted solution to allow it to settle fully, suction filter or pour out the clear liquid above the precipitate, wash the deposited precipitate with deionized water, and then wash and disperse it with absolute ethanol. Put it in an oven for drying at 60°C-100°C to remove moisture from the powder;

e. Take out the powder, carry out grinding and dispersing treatment, and calcine the powder at 360-600°C for 40-50 minutes to obtain Co-Mn-Ni ternary thermistor oxide nano-powder, powder The particle size is 50-150 nanometers, and there is no agglomeration when the calcination temperature is below 400°C, but soft agglomeration occurs when the calcination temperature is above 400°C. If soft agglomeration occurs, the size of the agglomerated particles is 0.1-4μm.

Detailed ways

Example 1

a. First weigh analytically pure cobalt acetate, manganese acetate, and nickel acetate chemical reagents according to Co:Mn:Ni=30:40:30, mix and dissolve them in deionized water, and control the molar concentration of metal ion acetate to 0.05mol/L , configured as the main component mixed solution;

b. Use oxalic acid as a precipitant, configure it into a precipitant solution, weigh the analytically pure oxalic acid with a molar ratio of 1.2:1 to the metal ion acetate, dissolve it in deionized water, stir and dissolve it fully, and control the molar concentration to be 0.05mol/ L;

c. Slowly pour the mixed solution of Co, Mn and Ni acetate into the oxalic acid precipitant solution for co-precipitation reaction, the temperature is 10°C, and the reaction is carried out while stirring continuously, and the pH value is controlled at 5 with ammonia water;

d. Leave the reacted solution to allow it to settle fully, suction filter or pour out the clear liquid above the precipitate, wash the deposited precipitate with deionized water, and then wash and disperse it with absolute ethanol. Put it in an oven for drying at 60°C to remove the moisture in the powder;

e. Take out the powder, carry out grinding and dispersing treatment, and calcine the powder at 360°C for 40 minutes to obtain Co-Mn-Ni ternary thermistor oxide nanopowder with a particle size of 50 -150 nm, no agglomerated particles.

Example 2

a. First, weigh analytically pure cobalt acetate, manganese acetate, and nickel acetate chemical reagents according to Co:Mn:Ni=50:40:10, mix and dissolve them in deionized water, and control the molar concentration of metal ion acetate to 0.2mol/L , configured as the main component mixed solution;

b. Use oxalic acid as a precipitating agent, configure it as a precipitating agent solution, weigh the analytically pure oxalic acid with a molar ratio of 1.5:1 to the metal ion acetate, dissolve it in deionized water, stir and dissolve it fully, and control the molar concentration to be 0.1mol/ L;

c. Slowly pour the mixed solution of Co, Mn and Ni acetate into the oxalic acid precipitant solution for co-precipitation reaction, the temperature is 50°C, and the reaction is carried out while stirring continuously, and the pH value is controlled at 6 with ammonia water;

d. Leave the reacted solution to allow it to settle fully, suction filter or pour out the clear liquid above the precipitate, wash the deposited precipitate with deionized water, and then wash and disperse it with absolute ethanol. Put it in an oven for drying at 80°C to remove the moisture in the powder;

e. Take out the powder, grind and disperse it, and calcinate the powder at 460°C for 45 minutes to obtain Co-Mn-Ni ternary thermistor oxide nano-powder with a particle size of 60 -120 nanometers, with soft agglomeration, the size of the agglomerated particles is 0.5-2μm.

Example 3

a. First weigh analytically pure cobalt acetate, manganese acetate, and nickel acetate chemical reagents according to Co:Mn:Ni=65:20:15, mix and dissolve them in deionized water, and control the molar concentration of metal ion acetate to 0.4mol/L , configured as the main component mixed solution;

b. Use oxalic acid as a precipitant, configure it into a precipitant solution, weigh the analytically pure oxalic acid with a molar ratio of 2.0:1 to the metal ion acetate, dissolve it in deionized water, stir and dissolve it fully, and control the molar concentration to be 0.2mol/ L;

c. Slowly pour the mixed solution of Co, Mn and Ni acetate into the oxalic acid precipitant solution for co-precipitation reaction, the temperature is 80°C, and the reaction is carried out while stirring continuously, and the pH value is controlled at 6 with ammonia water;

d. Leave the reacted solution to allow it to settle fully, suction filter or pour out the clear liquid above the precipitate, wash the deposited precipitate with deionized water, and then wash and disperse it with absolute ethanol. Put it in an oven for drying at 100°C to remove moisture from the powder;

e. Take out the powder, grind and disperse it, and calcine the powder at 600°C for 50 minutes to obtain the Co-Mn-Ni ternary thermistor oxide nano-powder with a particle size of 80 -150 nanometers, soft agglomeration occurs, and the size of the agglomerated particles is 1-4 μm.

Claims (1)

1, a kind ofly prepare the method for thermistor nm-class oxide powder, it is characterized in that pressing routine step and carry out with acetate:

A, take by weighing the acetate of Co, Mn, Ni as raw material at first respectively, its ratio is: Co: Mn: Ni=30-65: 20-40: 10-30, mix and dissolve in the deionized water, control metal ion molar concentration is 0.05-0.4mol/L, is configured to the major constituent mixed solution;

B, usefulness oxalic acid are configured to precipitant solution as precipitation reagent, take by weighing with metal ion acetate mole ratio to be 1-2.0: the pure oxalic acid of 1 analysis dissolves in the deionized water, abundant stirring and dissolving, and the control molar concentration is 0.05-0.2mol/L;

C, Co, Mn, Ni acetate mixed solution slowly poured into carry out coprecipitation reaction in the oxalic acid precipitation agent solution, temperature is 10 ℃-80 ℃, constantly stirs in the time of reaction, with ammoniacal liquor pH value is controlled at 5-6;

D, the solution left standstill that reaction is finished fully deposit it, suction filtration or topple over the clear liquid of sediment top, with the sediment that deposits, wash with deionized water, clean dispersion treatment with absolute ethyl alcohol then, put into baking oven and carry out dried, to remove moisture in the powder at 60 ℃-100 ℃;

E, taking-up powder, grind dispersion treatment, powder is carried out calcination processing at 360 1 600 ℃, time 40-50 minute, promptly obtain Co-Mn-Ni ternary system thermistor nm-class oxide powder, the powder granule size is in the 50-150 nanometer, calcining heat is not being reunited below 400 ℃, and calcining heat is having soft-agglomeratedly more than 400 ℃, as occur soft-agglomeratedly, and the agglomerated particle size is at 0.1-4 μ m.