JPH11236631A - Method for producing fine nickel powder by solid-phase reduction method and fine nickel powder obtained by the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing fine nickel powder which is spherical, has good crystallinity, has good filling properties, has fluidity, and is excellent in crystallinity by a solid phase reduction method, and is obtained by the method. Provided fine nickel powder. SOLUTION: A lanthanoid containing nickel chloride powder and, if necessary, a group III Sc or Y in the periodic table, IV
A raw material powder consisting of Ti, Δr, Hf, V, Nb, Ta of Group V, Cr, Mo, W of Group VI and chloride powder of Fe, Co of Group VIII; lithium, sodium or potassium; Solid-phase reduction with a mixture of a reducing agent powder of an alkali metal or an alkaline earth metal of magnesium, calcium, strontium or barium, and a powder of these alkali metal or alkaline earth metal chloride particles. I do.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fine nickel metal powder for an electronic component material such as an internal electrode of a multilayer ceramic capacitor by a solid-phase reduction method, and a fine nickel powder obtained by the method. Things.

[0002]

2. Description of the Related Art A conventional method for producing fine nickel powder is as follows.
The method is roughly classified into a dry method performed in a reducing atmosphere and a wet method using a reducing agent. Nickel powder produced by the dry method has high crystallinity, is suitable for sintering at a relatively high temperature, and has a characteristic of less shrinkage during sintering. It starts to form and has a relatively large shrinkage during sintering. Fine nickel powder is used in the production of fine electronic material components, for example, internal electrode materials for multilayer ceramic capacitors.

[0003]

In the miniaturization and high lamination of small electronic components such as multilayer ceramic capacitors, the required characteristics of nickel powder as an internal electrode material have become increasingly severe in recent years. In the production process of the multilayer ceramic capacitor, when laminating and sintering a dielectric and a nickel powder-containing paste as an electrode material, the particle shape, particle size, particle size distribution, dispersibility, filling,
It is becoming clear that crystallinity affects the sintering characteristics and greatly affects the product yield of the multilayer capacitor.

[0004] Nickel powder satisfying these characteristics is produced by a dry method because it is formed at a high temperature, has good crystallinity of the particles, has oxidation resistance, and has high density and good monodispersibility of the powder. The superiority of the nickel powder has been clarified, for example, in the production of the internal electrode of the multilayer ceramic capacitor described above, a fine nickel powder is made into a paste, and multilayered on a green sheet,
Sintered at high temperature under reducing atmosphere. However, as a behavior during sintering, the sintering start temperature and shrinkage rate fluctuate depending on the oxygen grade, grain shape, grain size, crystallinity, and filling properties of the surface of the fine nickel powder, and defects such as delamination and cracks occur. This is problematic in that the yield tends to decrease because of the occurrence of cracks.

Accordingly, an object of the present invention is to provide a method for producing a fine nickel powder which is spherical, has good crystallinity, has good filling properties, has fluidity, and is excellent in crystallinity by the solid-phase reduction method, and is obtained by the method. To provide a fine nickel powder.

[0006]

According to a first embodiment of the present invention, there is provided a lanthanoid containing Sc and Y of Group III in the periodic table, which is added as necessary. Group Ti, Ζr, Hf, group V, Nb, Ta, group VI Cr, Mo, W and VIII
A raw material powder comprising a chloride powder selected from the group consisting of Fe and Co, and a reducing agent powder comprising an alkali metal such as lithium, sodium or potassium or an alkaline earth metal such as magnesium, calcium, strontium or barium; It is characterized by a method for producing fine nickel powder which is mixed with an alkali metal or alkaline earth metal chloride powder and solid-phase reduced and uses argon gas or helium gas as an inert atmosphere. The reduction is performed at a temperature of 800 ° C. or more and 1200 ° C. or less, and the reduction product is washed with water to remove alkali metal or alkaline earth metal chloride, and then subjected to solid-liquid separation. Then, the solid or liquid separated slurry or cake-like wet fine nickel powder is dried while being crushed in a vacuum or a gas stream, and is dried rapidly to control the oxygen quality of the fine nickel powder. Is what you do.

In a second embodiment of the present invention, a nickel chloride powder is prepared by adding a reducing agent powder comprising an alkali metal such as lithium, sodium or potassium or an alkaline earth metal such as magnesium, calcium, strontium or barium; And a spherical particle obtained by mixing with an alkali metal or alkaline earth metal chloride powder and subjecting to solid-phase reduction, having a particle size of 0.1 μm or more and 5 μm or less, and having an oxygen grade of 1% It is characterized by the following fine nickel powder.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The present inventors have found that the particle shape is spherical and the particle size is 0.1 μm or more and 5 μm.
The present inventors have found a method for obtaining a fine nickel powder having good dispersibility, filling property and crystallinity of not more than μm and low oxygen grade of not more than 1%. That is, this method uses nickel chloride powder, lanthanoids containing Sc and Y of Group III in the periodic table, Ti, Δr, Hf of Group IV, V, Nb and T of Group V as necessary.
a, Group VI Cr, Mo, W or Group VIII Fe, C
o, a raw material powder comprising one or more chloride powders selected from the group consisting of lithium, sodium or potassium alkali metal or magnesium, calcium,
A reducing agent powder made of alkaline earth metal of strontium or barium, and a powder for suppressing heat generation of chloride of these alkali metal or alkaline earth metal are mixed and charged into a crucible type electric furnace, On the other hand, an inert gas such as an argon gas or a helium gas is introduced into the crucible-type electric furnace to perform metal thermite reduction in a solid phase in a reduction section in the crucible-type electric furnace, and in this case, the nickel chloride powder is used. It is preferable to reduce the reducing agent particles and the chloride particles for suppressing heat generation at a temperature of 800 ° C. or more and 1200 ° C. or less. 5 μm with a particle diameter of 0.1 μm or more, which is spherical, has good crystallinity, and is excellent in monodispersibility.
It has become possible to produce the following fine nickel powder and fine metal powder of raw material powder added as required.

The reducing agent powder is preferably a powder, but it can be used as long as it is generally less than a chip.
If the mass is too large, the reducing action is inferior, which is not preferable.
In addition, the lithium, sodium or potassium alkali metal or magnesium, calcium, strontium or barium chloride alkaline earth metal chloride powder suppresses heat generation due to a rapid reduction reaction, and sinters the generated fine metal powder. It is added for the purpose of prevention, and it is not necessarily required to be a powder, but a granule which is usually easily available is suitable for use.

The concentration of the nickel chloride vapor generated by heating the inside of the crucible-type electric furnace can be controlled by controlling the flow rate of an inert gas such as an argon gas or a helium gas with a flow meter or the like. By controlling the compounding ratio of the chloride powder for suppressing body and heat generation to the raw material powder, it can be controlled from 0.1 g / liter to 5 g / liter from the viewpoint of shortening the processing time and preventing generation of coarse particles. Is preferred.

When the raw material powder is subjected to solid-phase reduction with the reducing agent powder and the chloride powder for suppressing heat generation, the reason for setting the temperature to 800 ° C. or more and 1200 ° C. or less is as follows.
If the temperature is lower than 0 ° C., the reactivity is low, while if it exceeds 1200 ° C., the volatilization of chloride is remarkable.

As described above, the nickel chloride powder, a lanthanoid containing Sc and Y of group III in the periodic table, a Ti, Δr, Hf of group IV, V, Nb and T of group V in the periodic table, if necessary.
a, Group VI Cr, Mo, W or Group VIII Fe, C
a raw material powder comprising one or more chloride powders selected from the group consisting of an alkali metal such as lithium, sodium or potassium or magnesium, calcium, strontium or barium in a reducing section inside the crucible type electric furnace; A solid phase reduction is carried out with a mixture of a reducing agent granule composed of an alkaline earth metal and a granule for suppressing heat generation of chlorides of these alkali metals or alkaline earth metals, whereby fine particles having good sphericity and crystallinity are obtained. After the reduction product generated by the solid-phase reduction is pulverized into granules of about several millimeters, repulp, washed with water by repeating sedimentation, chloride of alkali metal or alkaline earth metal is removed. The fine nickel powder can be recovered by removing and then solid-liquid separation, and the group III Sc in the periodic table, Y-containing lanthanoids, Group IV Ti, Δr, Hf, Group V V, Nb, Ta, Group VI C
When one or more kinds of chloride powders selected from the group consisting of r, Mo, W or VIII group Fe and Co are added as raw material powders, these fine alloy powders can also be recovered.

Further, the slurry containing fine nickel powder solid-liquid separated or the wet fine nickel powder in the form of a cake is dried while being crushed in a vacuum or an air stream to obtain fine nickel powder having good monodispersibility. It can be manufactured. Then, by rapidly drying the obtained fine nickel powder, the oxygen quality of the fine nickel powder can be controlled to 1.0% or less, preferably from 0.1% to 1.0%.

Next, the present invention will be described with reference to the flow chart of FIG. 1. In the crucible type electric furnace, nickel chloride powder and, if necessary, group III S in the periodic table are added.
Lanthanoids containing c and Y, group IV Ti, Δr, H
f, a raw material powder composed of V, Nb, Ta of Group V, a chloride powder selected from Cr, Mo, W of Group VI and Fe and Co of Group VIII, and an alkali metal or magnesium of lithium, sodium or potassium; , Calcium, strontium or barium is charged with a mixture of a reducing agent particle made of an alkaline earth metal and a chloride particle for suppressing heat generation of these alkali metal or alkaline earth metal, and In a furnace, the raw material powder, the reducing agent particles and the chloride particles for suppressing heat generation are subjected to metal thermite reduction in a solid phase to recover a powdery reduction product. Then, the reduced product was pulverized into granules of about several millimeters, washed with water by repeating repulping and sedimentation, then removing alkali metal or alkaline earth metal chloride, and performing solid-liquid separation and solid-liquid separation. The slurry containing the fine nickel powder or the wet fine nickel powder in the form of a cake was dried while being crushed in a vacuum or air stream, whereby a fine nickel powder having good monodispersibility could be produced.

At this time, NiCl is placed in a crucible type electric furnace.
The basic reaction between the _two powders and the Mg powder, Ca powder or Na powder is shown in the following formula. (1) NiCl ₂ (g, 1, s) + Mg (g, 1, s)
_{= Ni (g, l, s} ) + MgCl 2 (g, l, s) (2) NiCl 2 (g, l, s) + Ca (g, l, s)
_{= Ni (g, l, s} ) + CaCl 2 (g, l, s) (3) NiCl 2 (g, l, s) + 2Na (g, l,
s) = Ni (g, l, s) + 2NaCl (g, l, s)

[0016]

[Table 1]

[0017]

EXAMPLE 1 129 g of anhydrous nickel chloride powder, 44 g (1.1 equivalent) of calcium metal as a reducing agent and 88 g of anhydrous calcium chloride were thoroughly mixed in a glow box.
Put it in a pure nickel reaction vessel and cover it, then put it in a stainless steel reaction vessel and replace it with argon gas.
The temperature was raised to 0 ° C. for 30 minutes, kept at 1000 ° C. for 30 minutes, then lowered to 800 ° C., and then the reaction vessel was taken out of the electric furnace and air-cooled to room temperature. After that, the reduction product is crushed by a crusher into granules of about several millimeters, and then repulp,
After repeating the sedimentation and washing with water to remove calcium chloride, fine nickel powder was recovered by solid-liquid separation. The solid or liquid separated slurry or cake-like wet fine nickel powder was dried while being crushed in an air stream at 150 ° C. The resulting nickel powder was visually observed by an SEM (scanning electron microscope), and as a result, was a fine nickel powder having a good monodispersibility and a spherical shape and a particle size of 0.5 μm to 2.0 μm. When the crystallinity of this powder was examined by X-ray diffraction, the crystallinity was good. The chlorine and calcium grades were determined by chemical analysis to be 10 ppm and 100 ppm, respectively.
The oxygen quality determined by the method was 0.25%.

Example 2 The same operation as in Example 1 was carried out except that magnesium was used as a reducing agent. The resulting nickel powder was SEM
As a result of visual observation, the powder was a fine nickel powder having a spherical shape with good monodispersibility and a particle size of 0.5 μm to 2.0 μm. When the crystallinity of this powder was examined by X-ray diffraction, the crystallinity was good. When the chlorine and magnesium grades were quantified by chemical analysis, respectively,
ppm and 100 ppm, and the oxygen quality determined by the RECO method was 0.75%.

Example 3 The same operation as in Example 1 was performed except that strontium was used as a reducing agent. The obtained nickel powder is SE
As a result of visual observation with M, it was a spherical shape with good monodispersity,
It was a fine nickel powder having a particle size of 0.5 μm to 2.0 μm. When the crystallinity of this powder was examined by X-ray diffraction, the crystallinity was good, and when the chlorine and strontium grades were quantified by chemical analysis,
It was 10 ppm and 100 ppm, and the oxygen quality determined by the RECO method was 0.35%.

Example 4 The same operation as in Example 1 was performed except that sodium was used as a reducing agent. The resulting nickel powder was visually observed with an SEM, and as a result, was a fine nickel powder having a good monodispersity spherical shape and a particle size of 0.1 μm to 1.0 μm. When the crystallinity of this powder was examined by X-ray diffraction, the crystallinity was good, and when the chlorine and sodium grades were quantified by chemical analysis, 10 pp
m and 100 ppm, and the oxygen quality determined by the RECO method was 0.75%.

Example 5 The same operation as in Example 1 was performed except that lithium was used as the reducing agent. The resulting nickel powder was visually observed with a SEM, and as a result, was a fine nickel powder having a good monodispersity spherical shape and a particle size of 0.5 μm to 2.0 μm. The crystallinity of this powder was examined by X-ray diffraction. The crystallinity was good, and the chlorine and lithium grades were determined by chemical analysis to be 10 ppm and 200 ppm, respectively. The oxygen grade was determined by the RECO method. Then, it was 0.35%.

Example 6 The same operation as in Example 1 was performed except that potassium was used as a reducing agent. The resulting nickel powder was visually observed with an SEM, and as a result, was a fine nickel powder having a good monodispersity spherical shape and a particle size of 0.1 μm to 1.0 μm. When the crystallinity of this powder was examined by X-ray diffraction, the crystallinity was good. The chlorine and potassium grades were determined by chemical analysis to be 10 ppm and 300 ppm, respectively. The oxygen grade was determined by the RECO method. Then, it was 0.75%.

Example 7 129 g of anhydrous nickel chloride powder and 58.07 g of anhydrous tungsten chloride, and calcium metal as a reducing agent.
2 g (1.1 equivalents) and 88 g of anhydrous calcium chloride
Was thoroughly mixed in a glow box, put in a pure nickel reaction vessel, covered, and then placed in a stainless steel electric furnace and replaced with argon gas.
For 30 minutes, and held at 1000 ° C. for 30 minutes.
The temperature was lowered to 0 ° C., and then the reaction vessel was taken out of the electric furnace and air-cooled to room temperature. Thereafter, the same operation as in Example 1 was performed on the reduced product. The resulting alloy powder was visually observed with a SEM, and as a result, was found to be spherical with good monodispersity and a particle size of 0.1.
It was a fine nickel-tungsten alloy powder having a size of 5 μm to 2.0 μm. When the crystallinity of this powder was examined by X-ray diffraction, the crystallinity was good. When the nickel, tungsten, chlorine and calcium grades were quantified by chemical analysis, they were 89.5% and 19.5%, respectively.
0.3%, 10ppm and 100ppm.
When the oxygen quality was determined by the CO method, it was 0.25%.

Example 8 The same operation as in Example 7 was carried out except that zinc chloride was used instead of tungsten chloride as the raw material chloride powder. The resulting nickel powder was visually observed with a SEM, and as a result, was a fine nickel powder having a good monodispersibility in a spherical shape and a particle size of 0.5 μm to 2.5 μm. When the crystallinity of this powder was examined by X-ray diffraction, the crystallinity was good, and the chemical analysis showed nickel grade, zinc grade,
When quantifying chlorine and calcium grades,
It is 89.0%, 10.5%, 15 ppm and 100 ppm, and when oxygen content is quantified by the RECO method, it is 0.1%.
5%.

Example 9 The same operation as in Example 7 was performed except that vanadium chloride was used instead of tungsten chloride as the raw material chloride powder. The resulting nickel powder was visually observed with an SEM, and as a result, was a fine nickel powder having a good monodispersity spherical shape and a particle size of 0.1 μm to 1.0 μm.
When the crystallinity of this powder was examined by X-ray diffraction, the crystallinity was good. When the nickel, vanadium, chlorine and calcium grades were quantified by chemical analysis, they were 90.3% and 9.5, respectively. %, 10ppm and 150p
pm, and the oxygen quality determined by the RECO method was 0.5%.

Example 10 The same operation as in Example 7 was performed except that cobalt chloride was used instead of tungsten chloride as the raw material chloride powder. The resulting nickel powder was visually observed by SEM, and as a result, was a fine nickel powder having a spherical shape with good monodispersibility and a particle size of 0.5 μm to 1.0 μm.
When the crystallinity of this powder was examined by X-ray diffraction, the crystallinity was good. When the nickel, cobalt, chlorine and calcium grades were quantified by chemical analysis, they were 90.5% and 9.0, respectively. %, 20ppm and 100pp
m, and the oxygen quality determined by the RECO method was 0.3%.

Example 11 129 g of anhydrous nickel chloride and 49 parts of anhydrous lanthanum chloride
g, reducing agent calcium metal 14.4 g (1.2 eq)
And 40 g of anhydrous calcium chloride (50% by weight, / 5
0 form a Ca-CaCl ₂ KeiTorukarada weight%)) was used to was carried out in the same manner as in Example 7. The obtained powder was visually observed with a SEM, and as a result, was a fine nickel-lanthanum alloy powder having a good monodispersibility and a spherical shape and a particle size of 0.5 μm to 5.0 μm. When the crystallinity of this powder was examined by X-ray diffraction, the crystallinity was good. When the nickel, lanthanum, chlorine, and calcium grades were quantified by chemical analysis, 6
7.9%, 32.0%, 10 ppm and 100 ppm.
%Met.

In each of the above embodiments, from a comprehensive viewpoint of price, availability, and ease of handling, magnesium, calcium, sodium, lithium, or potassium was used as the reducing agent, and tungsten, Zinc, vanadium, cobalt or lanthanum, further described the use of calcium chloride as a chloride for suppressing heat generation, magnesium, calcium,
Use alkaline earth metals such as barium other than sodium, lithium or potassium as reducing agents,
Lanthanides containing Sc, Y of group III, Ti, Hf of group IV, Nb, T of group V other than tungsten, zinc, vanadium, cobalt or lanthanum in the periodic table
a, Cr or Mo of Group VI or Fe of Group VIII may be used as a raw material chloride powder, or an alkali metal chloride of lithium, sodium or potassium other than calcium chloride or an alkaline earth of magnesium, strontium or barium. A similar effect can be obtained by using a metal chloride as a chloride for suppressing heat generation.

[0029]

As described above, according to the present invention, a raw material powder comprising nickel chloride powder or a specific metal chloride powder as required is prepared by mixing an alkali metal of potassium, sodium or lithium or magnesium, calcium, strontium or It is reduced with barium alkaline earth metal reducing agent particles, and further, potassium, sodium or lithium alkali metal or magnesium, calcium, strontium or barium alkaline earth metal chloride heat generation suppressing particles are produced. By the addition, it is possible to produce fine nickel powder having good crystallinity, low oxygen grade and low impurity grade, having a particle diameter of 0.1 μm or more and 5 μm or less, or a fine metal powder of the above-mentioned raw material metal chloride. This makes it possible to supply fine nickel powder that is fine for electronic materials, has good crystallinity, filling properties, and fluidity, and is also excellent in sinterability. Has become possible.

[Brief description of the drawings]

FIG. 1 is a flow chart illustrating the steps for performing the method of the present invention.

Claims (7)

[Claims] 1. A raw material powder comprising nickel chloride powder,
A reducing agent powder consisting of an alkali metal such as lithium, sodium or potassium or an alkaline earth metal such as magnesium, calcium, strontium or barium, and a powder of such an alkali metal or alkaline earth metal chloride are mixed. A method for producing a fine nickel powder, comprising performing solid phase reduction. 2. The raw material powder further comprises a lanthanoid containing Sc and Y of Group III in the periodic table, and a lanthanoid of Group IV in the periodic table.
i, Ζr, Hf, V of group V, Nb, Ta, C of group VI
2. The method for producing fine nickel powder according to claim 1, further comprising a chloride powder selected from the group consisting of r, Mo, W and VIII group Fe and Co. 3. The method for producing fine nickel powder according to claim 1, wherein the solid phase reduction is carried out at a temperature of 800 ° C. or more and 1200 ° C. or less using an argon gas or a helium gas as an inert atmosphere. 4. The fine nickel according to claim 1, wherein the reduced product is subjected to solid-liquid separation after removing alkali metal or alkaline earth metal chloride by washing with water. Powder manufacturing method. 5. The method according to claim 1, wherein the solid or liquid separated slurry or cake-like wet fine nickel powder is dried while being crushed in a vacuum or in an air stream.
5. The method for producing a fine nickel powder according to any one of 4. 6. The method according to claim 1, wherein the fine nickel powder is rapidly dried to control the oxygen quality.
The method for producing a fine nickel powder according to any one of the above items. 7. A nickel chloride powder comprising a reducing agent powder comprising an alkali metal such as lithium, sodium or potassium or an alkaline earth metal such as magnesium, calcium, strontium or barium, and a powder of the alkali metal or alkaline earth metal. 0.1 g of a sphere obtained by mixing with chloride powder and solid-phase reduction.
having a particle size of not less than 5 μm and not more than 5 μm, and having an oxygen grade of 1
% Nickel powder.