CN102674825A - Preparation method of M-type barium ferrite magnetic powder - Google Patents

Abstract

The invention relates to a new preparation method of M-type barium ferrite magnetic powder, and the method comprises the following steps of: mixing powdered nitrate barium (Ba(NO3) 2) and ferric nitrate (Fe(NO3)3.9H2O) in distilled water, thus obtaining a nitrate solution; dripping the nitrate solution into a citric acid water solution, and evenly mixing; adding concentrated ammonia water into the mixed solution, and adjusting the pH value; then, adding polyethylene glycol (PEG), and evenly mixing, thus obtaining sol; heating the sol in water bath, drying, and obtaining gel precursor through spread reaction; and finally, obtaining the M-type barium ferrite magnetic powder by calcining at 850 DEG C. The method provided by the invention has the remarkable advantages of being low in calcination temperature of the produced product BaFe12O19, short in calcination time, good in energy-saving effect, low in raw material cost, short in preparation time, easy in control of technological process, good in repeatability, low in requirement for production equipment, and suitable for large-scale technological production.

Description

A kind of preparation method of M type barium ferrite magnetic powder

Technical field

The invention relates to the preparation method of magneticsubstance, specifically, relate in particular to a kind of M type GP 500 (BaFe ₁₂O ₁₉) preparation method of magnetic powder.

Background technology

M type GP 500 (BaFe ₁₂O ₁₉) as the ferrimagnetism oxide compound, have the magnetic performance of multiple excellence.M type GP 500 has monadic magnetocrystalline anisotropy, (theoretical value is 72Am to the saturation magnetization height ²/ kg), chemical property is stable, erosion resistance strong and high-coercive force characteristics such as (theoretical value 6.7kOe).According to the Stoner-Wohlfarth model, the theoretical value of S=Mr/Ms approaches 0.5.Because its excellent magnetic performance, the YO of GP 500 accounts for about 50% of permanent magnet material, and ever-increasing trend is arranged.At present, the method for preparing GP 500 is numerous, and people have adopted chemical coprecipitation; Supercritical fluid drying; [Ying Liu, Michael G.B.Drew, Jingping Wang such as metallorganics hydrolysis method, glass crystallization method, salt-melting method, combustion method, organic resin method; Mi l in Zhang; And Yue Liu, Efficiency and purity control in the preparation of pure and/or aluminum-doped barium ferrites by hydrothermal methods using ferrous ions as reactants, Journal of Magnetism and Magnetic Materials; 2010,322:366-374.].These methods respectively have its characteristics, but all need could form the nano level GP 500 about the high-temperature heat treatment more than 1000 ℃ usually.

In order to obtain better magnetic property, thereby need the particle super-refinement of M type GP 500 be formed one-domain structure to reach nanometer scale.Sol-gel technology has molecular level intimate mixing, lower thermal treatment temp, is suitable for inherent advantages such as preparation nano particle and film, has become one of important method of preparation nanometer powder at present.Based on above idea, the present invention utilizes sol-gel method to prepare M type barium ferrite magnetic powder.

Summary of the invention

The objective of the invention is,, provide a kind of simple to operation, the preparation method of lower-cost M type barium ferrite magnetic powder for obtaining better nano level GP 500.

The present invention is achieved through following technical scheme.

With pulverous nitrate of baryta Ba (NO ₃) ₂With nitric acid Fe (NO ₃) ₃.9H ₂O is mixed in and obtains nitrate soln in the zero(ppm) water; Nitrate soln is dropped in the aqueous citric acid solution, mix; Add strong aqua and regulate the pH value; Add polyoxyethylene glycol (PEG) again, stir, obtain colloidal sol; With above-mentioned colloidal sol heating in water bath, drying, self-propagating reaction obtains Gel Precursor; Obtain M type barium ferrite magnetic powder through calcining again.Concrete preparation process is following:

(1) configuration nitrate soln.According to atomic ratio is Fe ³⁺: Ba ²⁺=12: 1 ratio takes by weighing iron nitrate, nitrate of baryta and is mixed with the solution that concentration of metal ions is 0.4mol/L respectively, leaves standstill; Then two kinds of solution are mixed, let its sufficient reacting, obtain red tan solution; Make nitrate soln, be the mixing solutions of iron nitrate and nitrate of baryta;

(2) configuration citric acid solution.According to Hydrocerol A and Fe ³⁺, Ba ²⁺Two kinds of ionic mol ratios are 2: 1, take by weighing Hydrocerol A and are dissolved in the zero(ppm) water, obtain colourless transparent solution, are citric acid solution;

(3) step (1) gained nitrate soln is added dropwise in step (2) the gained citric acid solution, stirs while dripping, uniform mixing drips an amount of strong aqua then, drips while stirring, and the pH value stabilization of control solution is 7.0 ± 0.5;

(4) in step (3) gained solution, add 0～20g/L polyoxyethylene glycol PEG, promptly take by weighing polyoxyethylene glycol and be dissolved in the zero(ppm) water, stir then and formed colloidal sol in 30 minutes;

(5) after the colloidal sol that step (4) is formed places 80 ℃ of water-bath 4h; The xeothermic thermosol that adds places 120 ℃ air dry oven to be incubated 20h colloidal sol, along with colloidal sol dehydrating solution viscosity increases gradually; Form the brown gel; After arriving 200 ℃ of temperature, xerogel begins self-propagating combustion, generates fluffy dendroid presoma spontaneous combustion powder;

(6) the presoma spontaneous combustion powder with step (5) grinds, and then powder is placed 450 ℃ of pre-burning 0～3h, calcines 3h down in 850 ℃ of high temperature then, and furnace cooling, can obtain the purpose product.

The invention has the beneficial effects as follows implement convenient, cost is low, technological process control easily, good reproducibility, suitability is wide, raw material sources are extensive, less demanding to production unit, be fit to the technology production in enormous quantities.And BaFe ₁₂O ₁₉Calcining temperature is low, and calcination time is short, and good energy-conserving effect has good magnetic performance.

Description of drawings

Fig. 1 is a process flow sheet of the present invention;

Fig. 2 (a) is the X-ray diffractogram spectrogram of embodiment one product, (b) is the magnetic hysteresis loop of embodiment one product;

Fig. 3 (a) is the X-ray diffractogram spectrogram of embodiment two products, (b) is the magnetic hysteresis loop of embodiment two products;

Fig. 4 (a) is the X-ray diffractogram spectrogram of embodiment three products, (b) is the magnetic hysteresis loop of embodiment three products;

Fig. 5 (a) is the X-ray diffractogram spectrogram of embodiment four products, (b) is the magnetic hysteresis loop of embodiment four products;

Fig. 6 (a) is the X-ray diffractogram spectrogram of embodiment five products, (b) is the magnetic hysteresis loop of embodiment five products.

Embodiment

Below in conjunction with embodiment the present invention is described further:

Embodiment 1

(1) be Fe according to atomic ratio ³⁺: Ba ²⁺=12: 1 ratio, the nitrate of baryta that takes by weighing iron nitrate, the 1g of 18.575g is dissolved in respectively and is mixed with the solution that concentration of metal ions is 0.4mol/L in 115mL and the 10mL deionized water.Leave standstill, mix, let its sufficient reacting, obtain the sorrel nitrate soln.Take by weighing the 20.92g Hydrocerol A and be dissolved in the 20mL zero(ppm) water, control Hydrocerol A and Fe ³⁺, Ba ²⁺Two kinds of ions and mol ratio be 2: 1.Nitrate soln is added dropwise in the citric acid solution, stirs while dripping, behind the uniform mixing, drip an amount of strong aqua again, drip while stirring, the pH value stabilization of control solution is 7.0.Stir 30min, form colloidal sol.

(2) after colloidal sol places 80 ℃ of water-bath 4h, place 120 ℃ air dry oven to be incubated 20h, form the brown gel, be heated to 200 ℃, xerogel begins self-propagating combustion, generates fluffy dendroid presoma spontaneous combustion powder.

(3) above-mentioned powder is ground,, calcining 3h under 850 ℃ of high temperature, and furnace cooling can obtain the purpose product.

Obtain barium ferrite powder at last, can be known by Fig. 1 (a), the principal crystalline phase of product is BaFe ₁₂O ₁₉Fig. 1 (b) be product under the foreign field effect of 2T, its saturation magnetization is 54.28emu/g, residual magnetization is 27.59emu/g, coercive force is 3.182kOe, S=Mr/Ms=0.508.

Embodiment 2

(1) be Fe according to atomic ratio ³⁺: Ba ²⁺=12: 1 ratio, the nitrate of baryta that takes by weighing iron nitrate, the 1g of 18.575g is dissolved in respectively and is mixed with the solution that concentration of metal ions is 0.4mol/L in 115mL and the 10mL deionized water.Leave standstill, mix, let its sufficient reacting, obtain the sorrel nitrate soln.Take by weighing the 20.92g Hydrocerol A and be dissolved in the 20mL zero(ppm) water, control Hydrocerol A and Fe ³⁺, Ba ²⁺Two kinds of ions and mol ratio be 2: 1.Nitrate soln is added dropwise in the citric acid solution, stirs while dripping, behind the uniform mixing, drip an amount of strong aqua again, drip while stirring, the pH value stabilization of control solution is 7.0.Add the 20g/L polyoxyethylene glycol in the gained solution, promptly take by weighing 3g polyoxyethylene glycol (PEG) and be dissolved in the 20mL deionized water, stir and formed colloidal sol in 30 minutes.

(2) after colloidal sol places 80 ℃ of water-bath 4h, place 120 ℃ air dry oven to be incubated 20h, form the brown gel, be heated to 200 ℃, xerogel begins self-propagating combustion, generates fluffy dendroid presoma spontaneous combustion powder.

(3) above-mentioned powder is ground, calcining 3h under 850 ℃ of high temperature, and furnace cooling can obtain the purpose product.

Obtain barium ferrite powder at last, can be known by Fig. 1 (a), the principal crystalline phase of product is BaFe ₁₂O ₁₉Fig. 1 (b) be product under the foreign field effect of 2T, its saturation magnetization is 58.05emu/g, residual magnetization is 28.97emu/g, coercive force is 3.370kOe, S=Mr/Ms=0.499.

Embodiment 3

The preparation method is identical with embodiment two, and different is presoma spontaneous combustion powder is at 450 ℃ of pre-burning 1h, then at calcining 3h under 850 ℃ of high temperature, and furnace cooling.

After grinding, can carry out 450 ℃ of pre-burnings for presoma spontaneous combustion powder, also can not carry out pre-burning, this will with experimentation in to add the concentration of polyoxyethylene glycol (PEG) relevant.

Obtain barium ferrite powder at last, can be known by Fig. 1 (a), the principal crystalline phase of product is BaFe ₁₂O ₁₉Fig. 1 (b) be product under the foreign field effect of 2T, its saturation magnetization is 40.97emu/g, residual magnetization is 21.59emu/g, coercive force is 0.997kOe, S=Mr/Ms=0.527.

Embodiment 4

The preparation method is identical with embodiment two, and different is that the polyglycol solution that adds is 25g/L, promptly takes by weighing 3.625g polyoxyethylene glycol (PEG) and is dissolved in the 20mL deionized water.

Obtain barium ferrite powder at last, can be known by Fig. 1 (a), the principal crystalline phase of product is BaFe ₁₂O ₁₉Fig. 1 (b) be product under the foreign field effect of 2T, its saturation magnetization is 34.24emu/g, residual magnetization is 17.74emu/g, coercive force is 1.552kOe, S=Mr/Ms=0.518.

Embodiment 5

The preparation method is identical with embodiment two, and different is that the polyglycol solution that adds is 25g/L, promptly takes by weighing 3.625g polyoxyethylene glycol (PEG) and is dissolved in the 20mL deionized water.Precursor powder is being calcined 3h and furnace cooling then at 450 ℃ of pre-burning 3h under 850 ℃ of high temperature.

Obtain barium ferrite powder at last, can be known by Fig. 1 (a), the principal crystalline phase of product is BaFe ₁₂O ₁₉Fig. 1 (b) be product under the foreign field effect of 2T, its saturation magnetization is 48.01emu/g, residual magnetization is 24.26emu/g, coercive force is 3.004kOe, S=Mr/Ms=0.505.

Claims (1)

1. the preparation method of a M type barium ferrite magnetic powder has following steps:

(1) configuration nitrate soln

According to atomic ratio is Fe ³⁺: Ba ²⁺=12: 1 ratio takes by weighing iron nitrate, nitrate of baryta and is mixed with the solution that concentration of metal ions is 0.4mol/L respectively, leaves standstill; Then two kinds of solution are mixed, let its sufficient reacting, obtain red tan solution; Make nitrate soln, be the mixing solutions of iron nitrate and nitrate of baryta;

(2) configuration citric acid solution

According to Hydrocerol A and Fe ³⁺, Ba ²⁺Two kinds of ionic mol ratios are 2: 1, take by weighing Hydrocerol A and are dissolved in the zero(ppm) water, obtain colourless transparent solution, are citric acid solution;

(3) step (1) gained nitrate soln is added dropwise in step (2) the gained citric acid solution, stirs while dripping, uniform mixing drips an amount of strong aqua then, drips while stirring, and the pH value stabilization of control solution is 7.0 ± 0.5;

(4) in step (3) gained solution, add 0～20g/L polyoxyethylene glycol PEG, promptly take by weighing polyoxyethylene glycol and be dissolved in the zero(ppm) water, stir then and formed colloidal sol in 30 minutes;

(5) after the colloidal sol that step (4) is formed places 80 ℃ of water-bath 4h; The xeothermic thermosol that adds places 120 ℃ air dry oven to be incubated 20h colloidal sol, along with colloidal sol dehydrating solution viscosity increases gradually; Form the brown gel; After arriving 200 ℃ of temperature, xerogel begins self-propagating combustion, generates fluffy dendroid presoma spontaneous combustion powder;

(6) the presoma spontaneous combustion powder with step (5) grinds, and then powder is placed 450 ℃ of pre-burning 0～3h, calcines 3h down in 850 ℃ of high temperature then, and furnace cooling, can obtain the purpose product.

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