JPH08188413A - Production of fine particle of boron-containing ceramic - Google Patents

Abstract

PURPOSE: To provide a process which can simply produce fine particles of boride ceramic by chemical reactions. CONSTITUTION: A metallic ion solution containing Ti and/or Tr ions or a combination thereof with other transition metal ions is admixed to a reducing agent solution containing boron hydride or an amine borane derivative to cause precipitation. When the metallic ion solution contains other transition metal ions, their concentrations are set to the same one as or lower than that of Ti and/or Zr ion. If they are higher, the precipitated fine particles are further heat-treated at 100-1,400 deg.C in an oxidative atmosphere.

Description

Detailed Description of the Invention

[0001]

The present invention relates to (Ti, Zr) -B by reacting a metal ion containing Ti, Zr or a transition metal as a main component with a reducing boron compound by a wet method.
The present invention relates to a method for producing -O-based and (Ti, Zr) -transition metal-BO-based ceramic fine particles.

[0002]

2. Description of the Related Art Boride ceramics have high strength and high conductivity like metal. Especially, boride with a transition metal such as Ti, Zr, and W can be mixed with various kinds of transition metals. Ceramics with the characteristics of Therefore, there is an increasing demand for boride ceramics having various compositions, but a drawback of boride ceramics is that fine particles for molding or sintering cannot be produced. Ceramic fine particles such as oxides, nitrides, and carbides can be easily produced by a gas phase reaction method of reacting in a high temperature state or plasma, but in the case of boride ceramics, there is no raw material gas that easily decomposes and reacts. Since boride is unlikely to occur, mass production is not possible. Further, fine particles such as oxide-based ceramics can also be produced by a chemical reaction method in which they are precipitated by hydrolysis or coprecipitation of an organometallic compound, but in the case of boride ceramics, there is no suitable chemical agent that causes decomposition and reaction. But mass production is not possible.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides a method for easily producing fine particles of boride ceramics by a chemical reaction method which has been difficult in the past.

[0004]

The first aspect of the present invention is to mix a metal ion solution containing Ti ions and / or Zr ions in a reducing agent solution containing a borohydride compound or an amine borane derivative, A second invention is a method for producing fine particles of boron-containing ceramics by reacting a reducing agent with a metal ion, and the second invention is the metal ion solution of the first invention, wherein one or two kinds of transition metal ions other than Ti and Zr are added. It is to further contain at least one species and to make the concentration thereof (molar concentration ratio: (Ti ion and / or Zr ion concentration) / (concentration of other transition metal ion) ≧ 1). Metal ion solution is Ti, Zr
Other than the above, one or more ions of other transition metals are further contained, and the concentration thereof is set to a molar concentration ratio of (Ti ion and / or Zr ion concentration) / (other transition metal ion concentration) <1. In addition, the obtained fine particles are heat-treated at 100 to 1400 ° C. in an oxidizing atmosphere.

[0005]

As a method for producing fine alloy particles, the inventors of the present invention first prepared an Fe-, Co-, Ni-, Cu-based alloy by adding a base metal ion solution to a reducing agent solution of a borohydride compound or an amine borane derivative. A method of mixing and reacting boron with a base metal (JP-A-64-65206, JP-A-2-232308, JP-A-3-630)
No. 9) was proposed, but it was found that oxide-based boride ceramics fine particles can be obtained by using an aqueous solution of Ti and Zr ions as the base metal ion solution by this method.

The borohydride compound of the reducing agent solution used in the present invention is represented by the general formula M (BH ₄ ) _n (where M is a metal and n is an integer), as in the case of the production of alloy fine particles. Where M is Li, Na, K, Be, Mg, Z
Examples thereof include n, Cd, Cu, Ag, Ga, Hf, Th, U and Pu. The amine borane derivative is BH ₃ −.
NH _x R _y (where R is an alkyl group, x and y are integers), and the alkyl group is a methyl group, an ethyl group,
It is inexpensive to use a lower alkyl group such as (iso) propyl group or (iso, tertial) butyl group. The solvent may be either an aqueous solvent or an organic solvent, but productivity,
Water is preferable in view of the production cost and the fact that the fine particles are oxide-based.

The metal ion solution containing Ti ions and / or Zr ions is prepared by adding a salt of Ti or Zr, preferably a water-soluble salt such as sulfate, nitrate, carbonate or chloride to an aqueous solvent or organic solvent. Dissolved in a solvent, such as Ti,
When it is desired to increase the concentration of one base metal of the ceramic in a solution containing both Zr ions, the concentration of one ion may be increased.

Another transition metal is added to the (Ti, Zr) -BO ceramic fine particles to form a ceramic (T
i, Zr) -transition metal-BO system, when it is desired to further improve the properties such as heat resistance, electrical conductivity, thermal conductivity, light absorption / emission property, and corrosion resistance, a metal ion solution containing Ti,
One or more transition metal ions other than Zr may be further contained. As the transition metal ion, a water-soluble salt such as a sulfate, a nitrate, a carbonate or a chloride may be added as in the case of the Ti salt or the Zr salt.
Care must be taken because the deposition state of the ceramic fine particles changes depending on the concentration ratio of Ti ions and / or Zr ions and the concentration of other transition metal ions.

That is, when the molar concentration ratio is (Ti ion and / or Zr ion concentration) / (concentration of other transition metal ion) ≧ 1, ceramic fine particles having a uniform composition are deposited in a high yield. When the molar concentration ratio is (Ti ion and / or Zr ion) / (concentration of other transition metal ion) <1, metal particles are included in a part of the deposited fine particles. In such a case, the obtained fine particles have 10
The heat treatment may be performed at 0 to 1400 ° C. This heat treatment is 3
When performed at 00 to 1100 ° C, the oxidation efficiency is improved, and
Particle fusion can be prevented by fusion of particles. Also,
The atmosphere is preferably an oxidizing atmosphere, for example, oxygen or air.

The mixing of the metal ion solution with the reducing agent solution is
For example, the latter solution may be gradually added dropwise while stirring the former solution to react the reducing agent with the metal ions, but the ceramic fine particles may have different compositions, yields, and particles depending on the reaction conditions during the mixing. The diameter changes. For example, the concentration of the borohydride compound or the amine borane derivative in the reducing agent solution and the concentration of the metal ion in the metal ion solution include the transition metal ions other than these elements even when the metal ion solution is only Ti or Zr ions. Even in the case of the above, by setting the former / latter ≧ 1 in terms of molar concentration ratio, ceramic fine particles having a uniform composition can be deposited.

When the metal ion solution is dropped onto the reducing agent solution, the metal ion solution diffuses and immediately reaches the alkalinity (acidity) or temperature of the reducing agent solution, so that the alkalinity or temperature of the reducing agent solution reacts. It becomes a condition. Since this reducing agent decomposes in the acidic region and the efficiency decreases, it is necessary to make the reducing agent solution alkaline. When the reducing agent solution has a pH of 8 to 13.5, the composition of the ceramic fine particles does not change significantly even if the pH changes within this range, and a stable precipitation amount can be obtained. However, if the pH is 10 to 13, the yield is improved. Although the pH of the aqueous solution obtained by dissolving the acid salts of transition metals such as Ti, Zr, etc. is weakly acidic, the pH of the reducing agent does not need to be specially adjusted under this condition because the amount of the reducing agent is very large.

The higher the temperature of the reducing agent solution, the shorter the precipitation time of the fine ceramic particles and the finer the particle size, but if the temperature is too high, the reducing agent decomposes. Therefore, the temperature is preferably 0 to 80 ° C. In particular, 10-60
When the temperature is set to ° C, decomposition of the reducing agent is suppressed, and the reaction rate and yield are improved.

The deposited ceramic fine particles may be filtered and then washed with water or an organic solvent. The ceramic fine particles obtained in the present invention have a very small particle size of 0.02 to 0.10 μm and a narrow particle size distribution. In this specification, in order to evaluate the change in the quality of the ceramic fine particles due to these manufacturing conditions, the oxygen concentration of each material is analyzed, and the manufacturing range in which the concentration is regarded as constant is defined as the conforming condition (Examples 5 to 5). 7).

[0014]

【Example】

Example 1 (1) Preparation of Solution (A) Reducing Agent Solution Potassium borohydride (K) having a concentration of 1 mol / l
An aqueous solution of BH ₄ ), sodium borohydride (NaBH ₄ ), and dimethylamine borane (DMAB) was prepared. The pH of these aqueous solutions was 10-11. (B) Metal Ion Solution Titanium sulfate and zirconium sulfate were dissolved in water to prepare a Ti salt solution and a Zr salt solution each having a Ti ion or Zr ion concentration of 0.1 mol / l. Further, both solutions were mixed at various ratios to prepare mixed solutions having different molar concentration ratios of Ti ions and Zr ions. (2) Production of Ceramic Fine Particles The reducing agent solution was brought to 40 ° C., a metal ion solution was dropped into the solution while stirring to deposit ceramic fine particles, and the deposited fine particles were filtered and washed with water. Table 1 shows the composition, crystal structure, and particle size of the obtained ceramic fine particles. The composition and crystal structure were determined by chemical analysis and X-ray diffraction, respectively, and the particle size was measured by a transmission electron microscope.

[0015]

[Table 1]

Example 2 Titanium sulfate, zirconium sulfate, iron sulfate, nickel chloride, cobalt chloride, sodium molybdate, sodium tungstate, and copper sulfate were dissolved in water and each had a concentration of 0.1 mol / l. An ionic solution was prepared. Along with this, other transition metal ion solutions are mixed with the Ti ion solution or the Zr ion solution or both solutions at various ratios, and the ion molar concentration ratio is (Ti ions and / or
Or Zr ion concentration) / (concentration of other transition metal ions)
= 7/3 mixed ionic solution was prepared. Then, after adjustment, these solutions were added to the reducing agent solution instead of the metal ion solution of Example 1. Tables 2 and 3 show the composition, crystal structure, and particle size of the obtained ceramic fine particles.

[0017]

[Table 2]

[0018]

[Table 3]

Example 3 In Example 2, the mixed ion solution had an ion molar concentration ratio (Ti ion and / or Zr ion concentration).
A mixed ion solution in which / (concentration of other transition metal ions) = 3/7 was used. Tables 4 and 5 show the composition, crystal structure, and particle size of the obtained ceramic fine particles.

[0020]

[Table 4]

[0021]

[Table 5]

Example 4 (1) Preparation of Solution (A) Reducing Agent Solution Aqueous solutions of potassium borohydride (KBH ₄ ) having various concentrations were prepared. The pH was in the range of 9-11.5. (B) Metal ion solution Titanium sulphate and copper sulphate are dissolved in water to give a metal having a molar ion concentration ratio of Ti ²⁺ : Cu ²⁺ = 7: 3 and a total ion concentration of 0.1 mol / l. An ionic solution was prepared. (2) Production of Ceramic Fine Particles A reducing agent solution of each concentration is brought to 10 ° C., a metal ion solution is dropped therein while stirring to precipitate ceramic fine particles, and then the fine particles thus precipitated are filtered to obtain water. Washed with. Fig. 1 shows the relationship between the molar concentration ratio of KBH ₄ / metal ion and the composition (atomic%) of the obtained ceramic fine particles, and Fig. 2 shows the yield of ceramic fine particles by the molar concentration ratio of reducing agent and metal ions. Show. The yield on the vertical axis in FIG. 2 is the standard deposition amount when the reducing agent concentration is 10 times the molar concentration of metal ions, and the deposition amount in this example is It is a standardized value of what percentage.

As shown in FIGS. 1 and 2, when the molar concentration ratio of the reducing agent and the metal ion is less than 1, the oxygen concentration increases, so that homogeneous ceramic fine particles cannot be obtained and the yield is low. . On the other hand, when the molar concentration ratio was 1 or more, ceramic fine particles having a stable composition were obtained and the yield was high.

Example 5 (1) Preparation of Solution (A) Reducing Agent Solution Sodium borohydride (NaB) having a concentration of 1 mol / l
It was prepared an aqueous solution of H _4). The pH was 10. (B) Metal Ion Solution Titanium sulfate, zirconium sulfate, and iron sulfate are dissolved in water, and the ion amount ratio is molar ratio Ti ²⁺ : Zr ⁴⁺ : Fe ^2+.
= 7: 2: 1 and a total ion concentration of 0.5 mol / l was prepared as a metal ion solution. (2) Production of Ceramic Fine Particles The temperature of the reducing agent solution was changed to 0 to 95 ° C., and the metal ion solution was added dropwise thereto while stirring to precipitate fine ceramic particles. Although metal particles were observed in the deposited fine particles, the composition was Ti _15.2 Zr _4.0 Fe _2.1 B _19.1 O when heated at 400 ° C. for 1 hour in the air after filtration and washing with water.
_59. Became ₆ ceramic fine particles of. FIG. 3 shows the relationship between the temperature of the reducing agent solution and the yield of the ceramic fine particles and the relationship between the temperature of the reducing agent solution and the oxygen concentration (atomic%). When the temperature of the reducing agent solution exceeds 95 ° C. , The yield was low.

Example 6 (1) Preparation of solution (A) Reducing agent solution An aqueous solution of potassium borohydride (KBH ₄ ) having a concentration of 1 mol / l and having various pH was prepared. (B) Metal ion solution Titanium sulfate is dissolved in water to obtain a Ti ion concentration of 0.6 mol /
1 of metal ion solution was prepared. (2) Production of Ceramic Fine Particles A reducing agent solution of each pH was adjusted to 30 ° C., and a metal ion solution was dropped into the solution while stirring to precipitate ceramic fine particles, which was filtered and washed with water. The composition of the fine particles was Ti _19.6 B _17.1 O _63.3 . FIG. 4 shows the relationship between the pH of the reducing agent solution and the yield of fine ceramic particles, and the relationship between the pH of the reducing agent solution and the oxygen concentration (atomic%). In addition,
The yield in FIG. 4 is a value obtained by normalizing the percentage of the amount of deposition in this example with respect to the amount of deposition when the amount of deposition when the pH of the reducing agent solution is 10 is the standard amount of deposition. Is.

Example 7 (1) Preparation of Solution (A) Reducing Agent Solution An aqueous solution of potassium borohydride (KBH ₄ ) having a concentration of 1 mol / l and a pH of 9.5 was prepared. (B) Metal ion solution Zirconium sulfate and nickel chloride are dissolved in water, and the ion amount ratio is Zr ²⁺ : Ni ²⁺ = 2: 8 and the total ion concentration is 0.1 mol / l. An ionic solution was prepared. (2) Production of Ceramics Fine Particles The temperature of the reducing agent solution was adjusted to 20 ° C., the metal ion solution was dropped into the solution while stirring, the ceramics fine particles were precipitated, filtered, and washed with water. Metal particles were found in the deposited fine particles, but after filtration and washing with water, 80 to 15 in the atmosphere.
When heat-treated at 00 ° C for 1 hour, the composition was Zr
It became ceramic fine particles of _3.3 Ni _12.4 B _13.3 O _71.0 . FIG. 5 shows the relationship between the heat treatment temperature and the particle size of the ceramic fine particles, and the relationship between the heat treatment temperature and the oxygen concentration (atomic%) in the ceramic fine particles.

[0027]

As described above, according to the method of the present invention, it is possible to produce boride ceramics fine particles by a wet method which is conventionally difficult.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the molar concentration ratio of KBH ₄ / metal ion and the composition (atomic%) of the obtained ceramic fine particles.

FIG. 2 is a graph showing the yield of ceramic fine particles according to the molar concentration ratio of a reducing agent and metal ions.

FIG. 3 shows the relationship between the temperature of the reducing agent solution and the yield of the ceramic fine particles, the temperature of the reducing agent solution and the oxygen concentration (atomic%).
It is a graph which shows the relationship with.

FIG. 4 shows the relationship between the pH of the reducing agent solution and the yield of the fine ceramic particles, the pH of the reducing agent solution and the oxygen concentration (atomic%).
It is a graph which shows the relationship with.

FIG. 5 is a graph showing the relationship between the heat treatment temperature and the particle size of the ceramic fine particles, and the relationship between the heat treatment temperature and the oxygen concentration (atomic%) in the ceramic fine particles.

Claims (4)

[Claims] 1. In a reducing agent solution containing a borohydride compound or an amine borane derivative, Ti ions and / or
Alternatively, a method for producing fine particles of boron-containing ceramics is characterized by mixing a metal ion solution containing Zr ions and reacting the reducing agent with the metal ions. 2. The metal ion solution according to claim 1 containing Ti, Z
One or more transition metal ions other than r are further contained, and the concentration thereof is (Ti ion and / or Zr ion concentration) / (other transition metal ion concentration) ≧ 1 in molar concentration ratio. A method for producing fine particles of boron-containing ceramics, comprising: 3. The metal ion solution according to claim 1 is Ti, Z
1 or 2 or more ions of other transition metals other than r are further contained, and the concentration thereof is (Ti ion and / or Zr ion concentration) / (other transition metal ion concentration) <1 in molar concentration ratio. In addition to the above, the method for producing boron-containing ceramic fine particles is characterized in that the obtained fine particles are heat-treated at 100 to 1400 ° C. in an oxidizing atmosphere. 4. The pH of the reducing agent solution is adjusted to 8 to 13.5 by setting the molar ratio of the concentration of borohydride compound or amine borane derivative in the reducing agent solution and the concentration of metal ion in the metal ion solution to the former / latter ≧ 1. 4. The method for producing fine particles of boron-containing ceramics according to claim 1, wherein the reaction is performed at 0 to 80 ° C.