KR102352835B1 - Nickel powder and its manufacturing method - Google Patents

Abstract

It is one of the subjects to provide nickel powder which shows a high compression density and has small volume shrinkage|contraction in high temperature processing, and its manufacturing method. Nickel powder contains nickel particles, and the ratio of Ni-Ni bonds among Ni-Ni bonds, Ni-OH bonds, and Ni-O bonds derived from nickel oxide on the surface of nickel particles is 50% or more, and heat at 1200 ° C. The shrinkage rate is 15% or less. The ratio of Ni-Ni bonds and thermal shrinkage were estimated by X-ray photoelectron spectroscopy and thermomechanical analysis, respectively.

Description

Nickel powder and its manufacturing method

One of the embodiments of the present invention relates to a nickel powder and a method for manufacturing the same.

Fine metal particles (metal powder) are used in various fields, for example, nickel powder is used as a raw material for internal electrodes of a multilayer ceramic capacitor (MLCC). Nickel powder can be manufactured by reducing the gas of nickel chloride with reducing gas, such as hydrogen. Alternatively, it is also possible to produce nickel powder by dispersing a nickel salt such as nickel oxide in a solvent and reducing it using a reducing agent such as hydrazine. The former is called the gas phase method, and the latter is called the liquid phase method. By appropriately treating the surface of the nickel powder obtained by this method, its characteristics and behavior at the time of sintering can be controlled (refer to Patent Documents 1 and 2).

[Prior art literature]

[Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. 2014-29013

Patent Document 2: Japanese Patent Laid-Open No. 2006-152439

One of the embodiments of the present invention aims to provide a nickel powder exhibiting a high compression density and having a small volume shrinkage during high-temperature processing, and a method for manufacturing the same.

One of the embodiments related to the present invention is nickel powder. Such nickel powder has a Ni-Ni bond on the surface, a Ni-OH bond, and a Ni-Ni bond ratio of 50% or more among Ni-O bonds derived from nickel oxide, and a thermal contraction rate of 15% or less at 1200°C . The ratio of Ni-Ni bonds and thermal shrinkage were estimated by X-ray photoelectron spectroscopy and thermomechanical analysis, respectively.

One of the embodiments related to the present invention is a method for producing nickel powder. This method involves treating the raw material nickel powder with a solution of a nitrogen-containing compound.

1] XPS measurement result of the nickel powder which concerns on one of embodiment of this invention.
[ Fig. 2 ] XPS measurement result of the nickel powder according to one embodiment of the present invention.
[FIG. 3] XPS measurement result of the nickel powder which concerns on one of embodiment of this invention.
4] XPS measurement result of the nickel powder which concerns on one of embodiment of this invention.
[ Fig. 5 ] Results of thermomechanical analysis (TMA) of nickel powder according to one embodiment of the present invention.
[ Fig. 6 ] Measurement result of compression density of nickel powder according to one embodiment of the present invention.
[Fig. 7] XPS measurement results of the nickel powder and the raw material nickel powder according to one embodiment of the present invention.
[FIG. 8] The manufacturing flow of the nickel powder which concerns on one of embodiment of this invention.

EMBODIMENT OF THE INVENTION Hereinafter, each embodiment of this invention is demonstrated, referring drawings etc. However, this invention can be implemented in various forms within the range which does not deviate from the summary, and is limited to the description of embodiment illustrated below, and is not interpreted.

Hereinafter, the nickel powder 100 which concerns on one embodiment of this invention and its manufacturing method are demonstrated.

1. nickel powder

The nickel powder 100 is an aggregate of particles of nickel, and the number average particle diameter of the nickel powder 100 can be 50 nm or more and 500 nm or less, 50 nm or more and 300 nm or less, or 100 nm or more and 250 nm. Accordingly, the nickel powder 100 contains at least one nickel particle having a particle diameter in the above range. As a number average particle diameter, the nickel powder 100 is observed with a scanning electron microscope, the particle diameter of several particle|grains (for example, 1000 pieces) can be measured, and the average value can be employ|adopted, for example. The particle diameter is the diameter of the smallest circle that inscribes the particle or the length of the long side of the rectangle of the smallest area that inscribes the particle. In addition, the nickel powder 100 may contain, for example, an organic compound including an amide group represented by the following formula together with nickel particles.

Nickel atoms contained in nickel particles exist in various bonding states. For example, the nickel atoms on the particle surface are not only Ni-Ni bonds, but also Ni-OH bonds derived from surface hydroxyl groups, _{Ni-C bonds derived from carbonate (NiCO 3} ), or Ni derived from nickel oxide (NiO _x ). A bond state such as an -O bond may be taken. On the surface of the nickel particles of the nickel powder 100, the ratio of Ni-Ni bonds among Ni-Ni bonds, Ni-OH bonds and Ni-O bonds is 50% or more. The ratio of Ni-Ni bonds may be 50% or more and 95% or less, 65% or more and 93% or less, 76% or more and 93% or less, or 85% or more and 93% or less. That is, on the surface of the nickel particle of the nickel powder 100, nickel exists as a zero-valent metal (metal nickel) in the ratio of the above-mentioned range. In addition, a nickel particle surface is a region from the surface of a nickel particle to 5 nm or 10 nm from the surface here. Although it is the inventor's estimate, when considering excluding nitrogen-containing compounds and organic compounds containing an amide group, the nickel particles constituting the nickel powder 100 have Ni having Ni-OH bonds and Ni-O bonds thinly on the outermost surface side, and , it is considered that many Ni having Ni-Ni bonds exist on the inner side from the outermost surface.

The bonding state of the nickel atoms can be estimated as follows, for example, by XPS (X-ray photoelectron spectroscopy) using a light source such as AlKα ray. The measured energy range of Ni2p is 884 to 844 (eV), and the measured energy range of C1s is 298 to 279 (eV). The area of the peak attributable to metallic nickel, ie, the peak derived from the Ni-Ni bond, is the sum of the peak areas of 852.4 (eV) and 858.5 (eV). The peak area attributed to the Ni-O bond is the sum of the peak areas of 853.4 (eV), 854.2 (eV), 855.3 (eV), 858.2 (eV), 860.6 (eV), 863.2 (eV) and 865.4 (eV) peak areas. do. The peak area attributed to Ni-OH bond is calculated|required by the following. First, the sum of the peak areas of 854.5 (eV), 855.7 (eV), 857.4 (eV), 861.1 (eV), 862.4 (eV) and 865.4 (eV) is obtained. From this summation, a peak area of 288.5 (eV) attributed to the Ni-C bond is subtracted to be the peak area derived from the Ni-OH bond. In addition, the peak position of the peak which belongs to metallic nickel can be specified if Ni as a standard product is used. The peak position of the peak attributable to the Ni-O bond can be specified using NiO as a standard product. The peak position of the peak attributable to the Ni-OH bond can be specified using _{Ni(OH) 2 .} The peak position attributed to the Ni-C bond can be specified using _{NiCO 3 .} In the present specification and claims, the ratio of the peak area attributed to the Ni-Ni bond to the sum of the peak area attributed to the Ni-Ni bond, the peak area attributed to the Ni-O bond, and the peak area attributed to the Ni-OH bond is It is the ratio of metallic nickel obtained by XPS measurement.

As described above, since the nickel particles contain metallic nickel on the surface in a high proportion, the nickel powder 100 exhibits excellent properties. For example, thermal shrinkage estimated by thermomechanical analysis is as low as 15% or less at 1200°C. The thermal shrinkage rate may be 5% or more and 14% or less, or 7% or more and 13% or less. Further, the compressed density of the nickel powder to 100 degrees, 4.8g / cm ³ at least 6.0g / cm ³ or less is a high value more than 5.0g / cm ³ at least 6.0g / cm ^3.

The measured value of the said thermomechanical analysis method is calculated|required by the following measurement. First, nickel powder 100 is shape|molded into phi 5mm and height 10mm pellet. Measurement conditions for thermomechanical analysis are: temperature range: room temperature to 1200°C, temperature rise rate: 5°C/min, atmosphere: _{a mixed gas of 2% H 2} , 98% N ₂ , 300 mL/min. The thermal contraction rate is calculated|required as the ratio of the shrinkage|contraction part calculated|required from the height (length) of the pellet at 1200 degreeC when shrinkage|contraction is completed with respect to the original height. In addition, the said compression density is calculated|required by the following measurement. Add 3 wt% camphor and acetone to 1 g of nickel powder, and stir until the mixture is dry. The resulting nickel powder is molded under a pressure of 0.5 t. The diameter, thickness and weight of the molded body are measured, and the value obtained thereby becomes the compressed density.

2. manufacturing method

As shown in FIG. 8 , the nickel powder 100 according to the embodiment of the present invention can be produced by using the nickel powder as a raw material, treating it with a nitrogen-containing compound, and drying the nickel powder. In such a production method, nickel powder produced by a gas phase method or a liquid phase method can be used as a raw material. Hereinafter, description will be given according to an example in which nickel powder (hereinafter, referred to as raw material nickel powder) manufactured by the vapor phase method is used as a raw material.

The production conditions of the raw material nickel powder can be appropriately selected. Usually, chlorine gas is blown into raw materials, such as a nickel pellet, a nickel powder, a nickel ingot, and nickel chloride is obtained. The raw material nickel powder can be obtained by vaporizing such nickel chloride and making the chlorinated nickel gas contact with reducing gas, such as hydrogen gas and hydrazine. This raw material nickel powder may be further treated with a sulfur-containing compound to form a film of nickel sulfide on the surface. The particle size of the raw material nickel powder is not particularly limited, and for example, a raw material nickel powder having a number average particle diameter of 50 nm or more and 500 nm or less, 50 nm or more and 300 nm or less, or 100 nm or more and 250 nm or less can be used.

The nickel powder 100 can be manufactured by treating the raw material nickel powder with a mixed solution or solution containing a nitrogen-containing compound (hereinafter, such a mixed solution or solution is also referred to as a dispersant). Examples of the solvent include water, lower alcohols having 1 to 4 carbon atoms such as ethanol and propanol, glycol solvents such as ethylene glycol and propylene glycol, and amide solvents such as N,N-dimethylformamide and N,N-dimethylacetamide. , nitrile-based solvents such as acetonitrile, and cyclic carbonate-based solvents such as ethylene carbonate can be used. Among them, water which is a non-flammable solvent and has low toxicity is suitable.

As the nitrogen-containing compound, a water-soluble nitrogen-containing compound is preferable. When water is used as the solvent, a nitrogen-containing compound having high solubility in water is used. The nitrogen-containing compound may be composed of a single component, and a mixture comprising a plurality of components may be used as the nitrogen-containing compound.

The nitrogen-containing compound can be selected from primary alkylamines and aliphatic amides. There is no restriction on the number of carbon atoms of the primary alkylamine and the number of carbon atoms of the alkyl group bonded to carbon or nitrogen of the aliphatic amide group, and it can be selected from 1 or more and 18 or less. In addition, the alkyl group may be either linear or cyclic, and may be branched. Examples of the primary alkylamine include tetradecylamine (C ₁₄ H ₂₉ NH ₂ ).

Alternatively, the nitrogen-containing compound may include a salt of a primary alkylamine and a carboxylic acid. As carboxylic acid, C1-C4 carboxylic acid, such as formic acid and acetic acid, can be used, for example. An example is a salt of tetradecylamine and acetic acid.

The above-described aliphatic amide may have a carboxyl group in the molecule. In this case, the nitrogen-containing compound may include a tertiary amine having an alkyl group further containing a hydroxyl group. As the aliphatic amide, for example, a compound represented by the following formula can be used.

[Formula 1]

Here, R ¹ is selected from an alkyl group having 6 to 18 carbon atoms, R ² is an alkyl group or alkenyl group having 1 to 4 carbon atoms, and X is an alkylene group having 1 to 5 carbon atoms. As an example, an _{undecyl group (C 11} H ₂₃ ), a methyl group, or an ethylene group may be selected ^{as R 1} , R ² , and X, respectively. As a tertiary amine which has an alkyl group containing a hydroxyl group, triethanolamine is mentioned, for example.

The treatment of the nickel powder 100 with the dispersing agent can be performed, for example, as follows. First, a slurry of the raw material nickel powder, that is, a mixture containing a solvent such as water and the raw material nickel is prepared, and this and the dispersant are mixed. The amount of the raw nickel powder in the slurry or the concentration and amount of the dispersant in the slurry is such that the concentration of the raw nickel powder in this mixture is 90% by weight or more and 99.5% by weight or less, and the concentration of the nitrogen-containing compound is 0.5% by weight or more and 10% by weight or less. appropriately controlled. The resulting liquid mixture is stirred in an atmosphere of an inert gas such as nitrogen or argon. Stirring time can be 1 minute or more and 1 hour or less, 1 minute or more and 30 minutes or less, or 1 minute or more and 10 minutes or less, and is typically 5 minutes. There is no restriction|limiting also in stirring temperature, For example, it may be room temperature (15 degreeC or more and 30 degrees C or less, or 15 degreeC or more and 25 degrees C or less), and stirring can also be performed while heating. In the case of heating, the temperature is 40°C or higher, and the stirring temperature can be selected in the range below the boiling point of the mixed solution. As shown in the Examples, in particular, by performing the treatment at room temperature, it is possible to effectively increase the proportion of nickel atoms present as metallic nickel on the surface. Thereafter, the temperature is raised and drying is performed under a nitrogen stream. Drying can be performed at 20 degreeC or more and 200 degrees C or less, or 110 degrees C or more and 150 degrees C or less, and it is 120 degreeC typically. After drying, it can classify with respect to the nickel powder 100.

According to the said manufacturing method, the ratio of the nickel atom which exists as metallic nickel in the surface is high, and it originates in this, and the nickel powder 100 which shows high compression density and small thermal contraction rate can be manufactured.

When the nickel powder is fired and used for electronic components such as electrodes, if the thermal contraction rate of the nickel powder is large, it is accompanied by a large volume change by heating. is known On the other hand, in the nickel powder 100 which concerns on this embodiment, compared with the case where it is processing with a dispersing agent, the ratio which the nickel atom exists as a zero-valent metal on the surface is high. As a result, as shown in the Examples, it was found by the inventors that the nickel powder 100 exhibited a small shrinkage rate and also had a large compression density. An increase in the compressive density results in a higher particle packing ratio per unit volume. Therefore, it is considered that the voids per unit volume are sufficiently reduced when the member is formed before the high heat treatment, and even if the nickel particles shrink during calcination, the effect is alleviated, and consequently, the occurrence of cracks can be suppressed and reduced. Moreover, when the thermal contraction rate becomes small at high temperature, crack generation can be suppressed further. For this reason, it is possible to significantly suppress defects such as cracks during heating and firing and peeling from adjacent structures. Accordingly, the nickel powder 100 can be used as a material for providing highly reliable electronic components in high yield.

Example

1. Example 1

In this example, the result of evaluating the characteristics of the nickel powder 100 manufactured according to the above-mentioned manufacturing method will be described.

1-1. Production of nickel powder

15 g of the raw material nickel powder with a number average particle diameter of 170 nm manufactured by the vapor phase method was disperse|distributed to 100 mL of water, and the nickel slurry was obtained. Next, the nitrogen-containing compound was dissolved in water to prepare an aqueous solution of the nitrogen-containing compound. As the nitrogen-containing compound, three types of Nichiyu Co., Ltd. Cation MA, Soft Tilt AL-T, and Eslim 221P triethanolamine neutralized products were used. In addition, Eslim 221P triethanolamine neutralized product used 2 types of 10% and 20% of active ingredients of a nitrogen-containing compound. The concentrations of the nitrogen-containing compound in the total of the raw material nickel powder and the nitrogen-containing compound were 1.0% by weight and 2.0% by weight.

The aqueous solution of the nitrogen-containing compound was added to the nickel slurry at room temperature and a nitrogen atmosphere, and two different liquid mixtures were prepared so that the concentration of each nitrogen-containing compound became the above-mentioned concentration. After stirring the mixture for 5 minutes, the supernatant was removed, washed 3 times with water, and further heated to 120° C. under nitrogen atmosphere and dried to obtain nickel powder 100. As a comparative example, a sample not using a nitrogen-containing compound was also adjusted to examine the effect of the nitrogen-containing compound.

1-2. XPS measurement

According to the measuring method described in the said embodiment, the ratio of metallic nickel in each nickel powder 100 was calculated|required. For XPS measurement, k-alpha+ manufactured by Thermo Fisher Scientific Co., Ltd. was used. The peak area was calculated|required with the following method.

For the spectrum obtained by the XPS measurement, after removing the background by the Shirley method, waveform separation was performed by a function combining the Lorentz function and the Gaussian function. Waveform-separated peaks were attributed to each binding as shown in Table 1. The peak area of the Ni-Ni bond is the sum of the peak areas of Ni2p3 metal1 and metal2, the peak area of the Ni-O bond is the sum of the peak areas of Ni2p3 and NiO1 to NiO7, and the peak area of the Ni-C bond is C1s It was set as the peak area of scan A, and the peak area of Ni-OH bond was set as the value obtained by subtracting the peak area of Ni-C bond from the sum of the peak areas of scan N from Ni2p3 scan I. The peak area ratio obtained in this way was made into the ratio of each bond.

[Table 1]

The results are shown in FIGS. 1 to 4 . 1 to 4 are, respectively, as nitrogen-containing compounds, Cation MA (FIG. 1), Soft Tilt AL-T (FIG. 2), Eslim 221P Triethanolamine neutralized product (active ingredient 10%) (FIG. 3), Eslim Measurement results of nickel powder 100 prepared using 221P triethanolamine neutralized product (active ingredient 20%) (FIG. 4). In these figures, the ratios of Ni-Ni bonds, Ni-OH bonds, and Ni-O bonds are shown as percentages. As shown in these figures, it was found that the ratio of Ni-Ni bonds was increased even when any nitrogen-containing compound was used as compared with the case where the nitrogen-containing compound was not used. Also, as a general trend, it was confirmed that the ratio of Ni-Ni bonds increased as the concentration of the nitrogen-containing compound increased.

Here, as a result of comparing the spectrum of the raw nickel powder and the nickel powder 100 prepared using the neutralized product of Eslim 221P triethanolamine (20% active ingredient) as a nitrogen-containing compound, the spectrum in the range of 390 eV to 410 eV, the raw material nickel powder is 398 eV It was found that the nickel powder 100 exhibits a peak at 400 eV compared to giving a peak in ( FIG. 7 ). The peak at 398 eV is a peak attributable to the metal nitride, and is considered to be derived from a Ni-N bond. On the other hand, the 400 eV peak is thought to originate from the amide bond contained in the nitrogen-containing compound, and this is also suggested from the increase of this peak intensity|strength with increase of the density|concentration of a nitrogen-containing compound. From this, it is suggested that the organic compound which has an amide group adsorb|sucks to the nickel particle surface of the nickel powder 100 which concerns on embodiment of this invention. In other words, it can be said that the nickel powder 100 contains an organic compound having an amide group.

1-3. Heat shrinkage measurement

The heat shrinkage rate was calculated|required by the said method using the nickel powder 100 manufactured using Eslim 221P triethanolamine neutralized product (active ingredient 20%) as a nitrogen-containing compound. As an apparatus, TMA8310 manufactured by Rigaku Co., Ltd. was used.

The results are shown in FIG. 5 . As shown in FIG. 5 , when the nitrogen-containing compound was not used, the shrinkage rate was 18%, and it was found that the volume was greatly reduced by heating. On the other hand, in the nickel powder 100 prepared using the nitrogen-containing compound, the shrinkage decreased as the concentration of the nitrogen-containing compound increased, and when the concentration of the nitrogen-containing compound was 2.0%, the thermal shrinkage was 10%. From these results, it was confirmed that the nickel powder 100 exhibits a low thermal shrinkage rate as the ratio of nickel atoms present as metallic nickel on the surface is higher.

1-4. Compressed Density Measurement

The compressed density was measured by the above method using the nickel powder 100 prepared using Eslim 221P triethanolamine neutralized product (active ingredient 20%) as a nitrogen-containing compound. ENERPAC S.E manufactured by Dongyang Hydraulic Machinery Co., Ltd. was used for the apparatus, and the load was changed to 0.5t, 1.0t, and 3t, and it measured.

The results are shown in Table 2 and FIG. 6 . As understood from Table 2 and FIG. 6, it was found that the compressed density of the nickel powder 100 tends to increase as the concentration of the nitrogen-containing compound increases, that is, as the ratio of nickel atoms present as metallic nickel on the surface increases. For example, when the concentration of the nitrogen-containing compound in the total of the raw material nickel powder and the nitrogen-containing compound was 2.0% by weight, it was confirmed that the compressed density increased by 15% compared with the nickel powder of the comparative example.

[Table 2]

Each of the above-described embodiments as an embodiment of the present invention may be implemented in appropriate combination as long as they do not contradict each other. Further, based on the display device of each embodiment, those skilled in the art to appropriately add, delete, or change the design, or to add, omit, or change the conditions of the process as long as the gist of the present invention is provided, fall within the scope of the present invention.

Even if it is an effect different from the effect caused by the shape of each embodiment described above, what is clear from the description of the present specification or can be easily predicted by a person skilled in the art is naturally interpreted as being caused by the present invention. .

100: nickel powder

Claims (13)

nickel particles, and
nitrogen-containing organic compounds
including,
The ratio of Ni-Ni bonds among Ni-Ni bonds, Ni-OH bonds and Ni-O bonds derived from nickel oxide on the surface of the nickel particles, estimated by X-ray photoelectron spectroscopy, is 50% or more,
Heat shrinkage estimated by thermomechanical analysis method is 15% or less at 1200℃,
The thermal contraction rate is composed of the nickel particles

The pellet obtained by heating a pellet of 5 mm and 10 mm in height from room temperature to 1200° C. at a temperature increase rate of 5° C./min under a mixed gas _{of H 2} (2%) and N ₂ (98%) at a flow rate of 300 mL/min. Nickel powder, which is the ratio of the shrinkage obtained from the height to the height. According to claim 1,
The number average particle diameter of the said nickel powder is 50 nm or more and 500 nm or less, Nickel powder. According to claim 1,
The nitrogen-containing organic compound contains an amide group, nickel powder. According to claim 1,
The nitrogen-containing organic compound is selected from a salt of a primary alkylamine and a carboxylic acid or an aliphatic amide containing a carboxyl group in the molecule, nickel powder. Including treating the raw material nickel powder with a mixture or solution containing a nitrogen-containing compound,
The nitrogen-containing compound is selected from a salt of a primary alkylamine and a carboxylic acid and an aliphatic amide containing a carboxyl group in the molecule, the method for producing nickel powder. 6. The method of claim 5,
The process is carried out at a temperature selected from the range of 15 ℃ or more and 30 ℃ or less, the method for producing nickel powder. 6. The method of claim 5,
The aliphatic amide is represented by the following formula,
[Formula 1]

R ¹ is an alkyl group having 6 to 18 carbon atoms, R ² is an alkyl group or alkenyl group having 1 to 4 carbon atoms, and X is an alkylene group having 1 to 5 carbon atoms. 6. The method of claim 5,
The treatment is carried out so that the concentration of the raw material nickel powder is 90% by weight or more and 99.5% by weight or less, and the nitrogen-containing compound is 0.5% by weight or more and 10% by weight or less in the total of the raw material nickel powder and the nitrogen-containing compound, Method for producing nickel powder. 6. The method of claim 5,
The raw material nickel powder is produced by a vapor phase method, a method for producing nickel powder. 6. The method of claim 5,
The solvent of the solution is water, a method for producing nickel powder. 6. The method of claim 5,
In the above treatment, the ratio of Ni-Ni bonds among Ni-Ni bonds, Ni-OH bonds, and Ni-O bonds resulting from nickel oxide of the nickel particles contained in the nickel powder is 50% or more, and the nickel It is carried out so that the thermal contraction rate of the powder is 15% or less at 1200 ° C,
The ratio of the Ni-Ni bonds and the thermal shrinkage are estimated by X-ray photoelectron spectroscopy and thermomechanical analysis, respectively,
The thermal contraction rate of the nickel powder

The pellet obtained by heating a pellet of 5 mm and 10 mm in height from room temperature to 1200° C. at a temperature increase rate of 5° C./min under a mixed gas _{of H 2} (2%) and N ₂ (98%) at a flow rate of 300 mL/min. The method for producing a nickel powder, which is a ratio to the height of the shrinkage obtained from the height. delete delete

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