JPH01167213A - Production of fine powder of titanium diboride - Google Patents

Abstract

PURPOSE:To easily obtain fine powder of TiB2 having uniform and fine particle size and excellent sintering property, by adding specific amounts of fine particles of TiB2 or fine particles of titanium oxide as additives in the course of baking titanium oxide, B oxide and carbon in a non-oxidizing atmosphere at a high temperature. CONSTITUTION:TiB2 is produced by baking titanium oxide, a boron oxides (e.g., boric acid) and a carbon source (e.g., furnace black) in a non-oxidizing atmosphere (e.g., CO atmosphere) at 1300-1700 deg.C. In the above process, 100pts. wt. of the above titanium oxide having an average particle diameter of 0.05-5mum is added with 0.05-100 pts.wt. of TiB2 having an average particle diameter of <=3mum or titanium oxide having an average particle diameter of <=0.05mum and baked. The process affords fine powder of TiB2 having particle diameter of about 1-3mum which is necessary to obtain a sintered TiB2 having excellent quality.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for producing fine titanium diboride powder.

Titanium diboride has the characteristics of a high melting point, high strength, high hardness, and high corrosion resistance, and has been traditionally used as cutting tools, heat engine parts, etc.

[Prior art] As a method for producing titanium diboride, the direct reaction method in which titanium and boron are directly reacted is well known, but the raw materials are expensive and the reaction proceeds at high temperatures, making it difficult to produce titanium diboride. Titanium has a large particle size. In addition, a more industrial production method is known, in which titanium oxide is borated in the presence of carbon and boric anhydride, but even with this method, it is difficult to obtain titanium diboride powder with a uniform and small particle size. It is not easy, for example, Japanese Patent Application Laid-Open No. 61-13251.
Publication No. 1 discloses a method of carrying out the boration reaction under reduced pressure of 50 Torr or less, but this requires expensive equipment and
It was not necessarily an industrially superior method, as it was not easy to operate under good conditions.

Titanium diboride has high hardness and is extremely difficult to grind into fine particles. Although uniform and fine titanium diboride powder is desired in order to obtain a good sintered body by taking advantage of the various physical properties described above, the reality is that there is no industrially easy manufacturing method.

[Specific means for solving the problem] The present inventors
In view of these problems of the prior art, the present invention was arrived at after intensive study.

That is, the present invention provides a method for obtaining titanium diboride by firing titanium oxide, boron oxide, and carbon at a temperature of 1300 to 1700 ° C. in a non-oxidizing atmosphere.
To 100 parts by weight of titanium oxide with an average particle size of 0.05 to 5 μ, add 0.05 to 0.05 of titanium diboride with an average particle size of 3 μ or less or titanium oxide with an average particle size of 0.05 μ or less as an additive.
This is a method for producing fine titanium diboride powder, characterized in that 100 parts by weight of titanium diboride is added.

In the present invention, fine titanium diboride or titanium oxide is added as an additive to titanium oxide, boron oxide, and carbon as the main raw material powders to obtain finer titanium diboride, and subjected to the reaction. . When titanium diboride is used as an additive, it is preferable that the particle size is smaller, and in order to obtain a fine powder of about 1 to 3 μm, which is required to obtain a good titanium diboride sintered body, it is necessary to Although it depends on the particle size of titanium oxide, it is preferable to use titanium diboride having a particle size of 3 μm or less as an additive.

The object of the present invention can also be achieved by using fine titanium oxide instead of fine titanium diboride as an additive, but in this case, of course, compared to the titanium oxide used as the main raw material, , it is necessary to use finer titanium oxide, and in order to obtain the above-mentioned fine titanium diboride, fine titanium oxide of 0.05 μm or less is preferable. The amount of titanium diboride and titanium oxide added as these additives is preferably in the range of 0.05 to 100 parts by weight based on 100 parts by weight of titanium oxide in the main raw material. If it is less than this, the degree of refinement of the produced titanium diboride due to the effect of the additive is small, and it is not economical to make it more than this.

As the titanium oxide powder used as the main raw material powder in the present invention, titanium oxide powder with a small particle size is preferable because the reaction rate is higher, but titanium oxide with a particle size of 0.05μ or less is expensive, so Titanium oxide is preferred.

As the boron oxide used as a raw material, boric acid or boric anhydride can be used, and the amount added is 70 parts by weight or more per 100 parts by weight of total titanium oxide, and as a carbon source, furnace black, acetylene black, etc. can be used. , amorphous carbon powder such as lamp black, water-soluble carbohydrates such as monosaccharides and polysaccharides, and sparingly soluble oils and fats such as tar and pitch, and the amount added is 72 parts by weight or more based on the total titanium oxide. It is.

In the present invention, it is not clear how titanium diboride and titanium oxide as additives contribute to making the produced titanium diboride finer and more uniform in particle size.
The fine titanium diboride generated in the initial stage of the reaction by the reaction of pre-existing fine titanium diboride or fine reactive titanium oxide catalytically promotes nucleation, resulting in a uniform and fine powder. Conceivable.

The firing temperature in the present invention is 1300 to 1700°C.
Below this range, the reaction rate is not sufficient, and above this range, the particle size tends to increase due to abnormal grain growth of the titanium diboride produced, and it is not economical in terms of energy. Further, the reaction is carried out in a non-oxidizing atmosphere such as a CO atmosphere generated by the reaction or an inert gas atmosphere such as argon. The reaction pressure is not particularly limited, and normal pressure is sufficient, but it is of course possible to conduct the reaction in a reduced pressure system in consideration of the reaction rate and the like.

The present invention will be explained in detail below using examples.

Examples 1 to 8, Comparative Example 1 Main raw materials titanium oxide, carbon powder, boric anhydride, and seed crystals such as titanium diboride and titanium oxide were mixed in a ball mill at the composition ratio shown in Table 1 to prepare raw material powder. This was then calcined to obtain titanium diboride powder. The reaction conditions and the physical properties of the produced titanium diboride are also shown in Table 1.

Furthermore, the particle size distribution of the powders obtained in Example 2 and Comparative Example 1 was measured using ethanol as the medium using a centrifugal sedimentation light transmission type particle size distribution analyzer (5A-CP2) manufactured by Shimadzu Corporation. The results are shown in FIGS. 1 and 2. Further, a SEM photograph of the suspended grain structure of the powder obtained in Example 2 is shown in FIG.

[Effects of the Invention] According to the present invention, uniform fine titanium diboride fine powder with excellent sinterability can be easily obtained.

[Brief explanation of the drawing]

FIGS. 1 and 2 show particle size distribution curves of powders obtained in Examples and Comparative Examples. Figure 3 is an SEM of the particle structure of the powder obtained in the example.
The photo is shown. Patent applicant Central Glass Co., Ltd. Figure 1 Particle size distribution Particle size distribution

Claims (1)

[Claims] In a method for obtaining titanium diboride by firing titanium oxide, boron oxide and carbon at a temperature of 1300 to 1700°C in a non-oxidizing atmosphere, an average particle size of 0.05
Titanium diboride with an average particle size of 3 μ or less or an average particle size of 0 as an additive to 100 parts by weight of titanium oxide with a particle size of ~5 μ
．． A method for producing fine titanium diboride powder, which comprises adding 0.05 to 100 parts by weight of titanium oxide having a particle diameter of 0.05 μm or less.