JPH0525812B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a composite compound of titanium nitride and titanium oxide.

Titanium nitride has a high melting point, high hardness, chemical stability, and excellent electrical conductivity. Utilizing these properties, it is used as a superhard material and an electrically conductive material, and its use as a superconducting material and electrically conductive additive material such as silicon nitride sintered bodies is also being developed.

Titanium nitride is often a non-stoichiometric compound, and its properties vary greatly depending on the nitrogen content, impurities, particle size characteristics, etc. A method for producing titanium nitride using a solid phase-vapor phase reaction is a method in which titanium metal powder is heated at 800°C or higher in a nitrogen or ammonia atmosphere to nitride it.

A method of igniting titanium dioxide in an electric blast furnace in a nitrogen atmosphere.

Titanium dioxide in ammonia stream from 1400~
Method of heating at 1500℃.

etc. However, in these production methods, the titanium nitride produced is treated at high temperatures, so the particle size becomes large and the particles of the obtained product are also non-uniform. The present inventor conducted repeated studies to obtain titanium nitride consisting of uniform particles with a small particle size, and as a result, the present invention was achieved.

Currently, common black conductive pigments include carbon black and titanium monoxide
91037, Japanese Unexamined Patent Publication No. 58-164653) is known. However, carbon black has a large surface area and is hydrophobic, making it difficult to handle when turning it into a paint. Furthermore, it is believed that industrially produced carbon black may be contaminated with benzpyrene, a carcinogenic substance. ing. Furthermore, since titanium monoxide is obtained by treating titanium dioxide in the same manner as in the present invention, it is compatible with resin and is non-toxic. Furthermore, it has the disadvantage of being chemically unstable. Other black pigments include triiron tetroxide and lower titanium oxide.
There is TiOn (1<n<2). However, since triiron tetroxide is ferromagnetic, it has the disadvantage that it is difficult to maintain dispersion stability. Low-order titanium oxide is obtained by heating a mixture of titanium dioxide powder and metallic titanium powder in a vacuum, or by heating titanium dioxide powder at high temperature with hydrogen gas, so it has a small particle size and high uniformity. It is difficult to obtain the product.

The present invention provides a powder using a composite of titanium nitride and titanium oxide, which eliminates the drawbacks of the above-mentioned materials and is useful as, for example, a black pigment or a conductive material. The method of the present invention is to prepare titanium dioxide or hydrous titanium oxide powder in a mixed gas of ammonia gas and hydrogen gas.
It is characterized by heating and nitriding at a temperature of 800 to 1000°C. That is, as mentioned above, titanium nitride can be obtained by treating titanium dioxide in an ammonia gas stream at high temperature for a long time, but titanium nitride created by this method has a small particle size because sintering occurs between particles. Small ones are difficult to obtain. As a result of intensive studies, we were able to obtain a good black conductive powder with uniform and small particle size by thermal reduction nitriding with a mixed gas of ammonia and hydrogen. As a result of X-ray diffraction and nitrogen analysis (CN coder manufactured by Yanaco), the composition of the product was found to be a composite of titanium nitride and titanium oxide.

The raw materials used in the present invention are titanium dioxide powder and
Hydrous titanium oxide powder and flaky mica coated with titanium dioxide or hydrous titanium oxide, etc. can be used. As the hydrous titanium oxide, metatitanic acid, orthotitanic acid, etc., which are intermediates in the manufacturing process of titanium dioxide (rutile, anatase), can be used. However, in this case, sintering occurs more easily than when titanium dioxide is treated, and the treatment must be performed at a lower temperature.
The titanium dioxide may be either rutile or anatase, and may be surface-treated to prevent sintering. The particle size of the obtained product is 0.05μ to maintain the particle size of the raw material.
Can be obtained in a wide range of 1μ. If the reaction temperature is higher than 1000°C, grain growth will become significantly large and non-uniform due to sintering. Further, the nitriding reaction is difficult to proceed at low temperatures, and the reaction time is also required to be extremely long. Therefore, in order to complete the reaction in 1 to 4 hours, the temperature must be 800°C or more and 1000°C or less.

It is desirable that the ammonia/hydrogen mixture has an ammonia ratio of at least 50%. By increasing the proportion of ammonia, the color of the product can be changed from brown to dark brown to blue-black. A similar product can also be obtained by reducing titanium dioxide or hydrous titanium oxide to lower titanium oxide TiOn (n<2) by hydrogen reduction, and then treating it with an ammonia/hydrogen mixed gas for a short time. This method can reduce the amount of ammonia required.
The best black pigment was also obtained by this method.
In order for the reaction to proceed uniformly, the flow rate of the mixed gas is desirably large within a range that does not cause scattering of the sample or a drop in the temperature of the reaction system. It is also necessary to preheat the gas mixture. For the same purpose, it is preferable to use a reactor with a sample rotation mechanism rather than a stationary reactor.

Example 1 Titanium dioxide fine particles (rutile type,
Teikoku Kako trade name MT-500B, specific surface area 40m ² /
g) 10 g was placed in a boat and inserted into a quartz reaction tube with a temperature of 1000°C, an ammonia flow rate of 1500 ml/min, and a hydrogen flow rate of 500 ml/min, and nitriding treatment was performed for 1 hour. Thereafter, the boat was taken out to room temperature in the same gas atmosphere, cooled, and the inside of the reaction tube was washed with nitrogen gas, and then the product was collected. The obtained product exhibited a blackish brown color, and the peak intensity ratio of TiN/TiO ₂ (rutile) by X-ray diffraction was 5/11.

Results of nitrogen analysis using CN coder as TiN
Nitrogen equivalent to 20% was confirmed. Also, the specific resistance is 1.5
Ω・cm, and the average particle diameter according to electron micrograph is
It was 0.05μ.

Example 2 10 g of the titanium dioxide fine particles used in Example 1 were heated at a reaction temperature of 1000°C, an ammonia flow rate of 1500 ml/min,
When the reaction time was 1 hour at a hydrogen flow rate of 200 ml/min, the product exhibited a black color and was determined by X-ray diffraction.
The peak intensity ratio of TiN/TiO ₂ (rutile) was 5/4.

Moreover, the specific resistance was 0.5Ω·cm.

Example 3 10 g of metatitanic acid (Teikoku Kako, process intermediate) was reacted at a reaction temperature of 800°C and an ammonia flow rate of 1000 ml/min.
When treated at a hydrogen flow rate of 100 ml/min for a reaction time of 3 hours, the obtained product exhibited a black-blue color, and the TiN/TiO ₂ (anatase) peak intensity ratio by X-ray diffraction was 1/4. Further, the specific resistance was 4Ω·cm, and the average particle diameter was 0.05μ.

Comparative Example 1 10g of metatitanic acid similar to Example 3 was reacted at
When treated at 1000° C. for 1 hour at a hydrogen flow rate of 900 ml/min, the obtained product exhibited a blue-black color and was determined by X-ray diffraction to be lower titanium oxide (Ti ₆ O ₁₁ main phase).
Further, the average particle diameter as determined by electron micrograph was approximately 0.5μ.

Example 4 After processing for 1 hour under the same conditions as in Comparative Example 1, the reaction gas was changed to a hydrogen flow rate of 900 ml/min and an ammonia flow rate of 900 ml/min, and the treatment was continued for 5 minutes. The obtained product has a black color and is TiN/TiO ₂ by X-ray diffraction.
The peak intensity ratio of (rutile) was 1/6, and the average particle diameter by electron micrograph was about 0.5μ. Further, the specific resistance was 3Ω·cm.

Example 5 5 g of hydrous titanium oxide coated mica before firing prepared by the method of JP-A-60-11560 Example 1 was reacted for 1 hour at a reaction temperature of 1000°C, an ammonia flow rate of 1500 ml/min, and a hydrogen flow rate of 200 ml/min. When treated, the product took on a dark brown color. Also, the specific resistance is 2
It was Ω・cm.

Claims (1)

[Claims] 1 Titanium dioxide and/or hydrated titanium oxide in an air stream containing ammonia and hydrogen at a concentration of 800 to 1000
A method for producing a titanium nitride/titanium oxide composite, which is characterized by heat treatment at a temperature of °C. 2 A first structure in which titanium dioxide and/or hydrous titanium oxide is supported on flaky mica as a coating.
Section method. 3 A first method using a gas mixture of ammonia and hydrogen, with a mixture ratio of ammonia of at least 50%.
Section or method of Section 2. 4 Titanium dioxide and/or hydrous titanium oxide are first reduced with hydrogen to produce lower titanium oxide.
The method of item 1 or item 2, in which after TiOn (n<2) is formed, the treatment is performed in an air stream containing a large amount of ammonia.