JPH06239664A - Fiber-reinforced ceramic and its production - Google Patents

Abstract

PURPOSE:To obtain a fiber-reinforced ceramic excellent in abrasion resistance and improved in toughness and defect resistance. CONSTITUTION:A fiber-reinforced ceramic is characterized by containing at least one kind of diamond and/or cubic boron nitride, at least one kind of titanium carbide whisker, titanium nitride whisker and titanium carbonitride whisker, and preferably the particles of at least one kind of the carbonate, nitride and carbonitride of titanium. The whisker is preferably contained in an amount of 5-95vol.%, and the whisker having a diameter of <=5mum and an aspect ratio of >=3 is preferably contained in an amount of <=5% based on the whole amount of the whisker.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a fiber reinforced ceramic containing a super-hard material such as diamond and cubic boron nitride and also containing a fibrous substance such as whiskers and excellent in high toughness, which is particularly suitable for a tool. And a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, sintered bodies made of diamond or cubic boron nitride have been used as various cutting tools because they have high hardness. For example, a diamond sintered body is used for cutting aluminum alloy or FRP, and a cubic boron nitride sintered body is used for cutting steel.

[0003]

However, although diamond and cubic boron nitride (cBN) sintered bodies are excellent in wear resistance, they are poor in toughness. For example, when used as a cutting tool, the cutting edge is easily chipped There was a flaw.

[0004]

Means for Solving the Problems The inventors of the present invention have made extensive studies on the above problems, and as a result, titanium carbon and nitride are originally excellent in non-reactivity with iron. Even if added to diamond or cBN, diamond or c
It has been found that the wear resistance of BN is not deteriorated, and the addition of this as whiskers can impart extremely excellent toughness. Based on this, titanium compound whiskers can be used as diamond or cB
Dispersion and inclusion in N-type ceramics solved the above-mentioned drawbacks in terms of toughness, and obtained a material having excellent toughness.

That is, the fiber-reinforced ceramics of the present invention is
It is characterized in that at least one of titanium carbide whiskers, nitride whiskers, and carbonitride whiskers is contained in a component composed of at least one of diamond and cubic boron nitride, and the carbide of titanium is contained in the ceramic. , Particles of at least one of nitride and carbonitride may be contained, and the whiskers are contained in a proportion of 5 to 95% by volume, and the diameter of the whiskers is 5 μm or less and the aspect ratio is 3 or more. It is recommended to contain 5% or more of the total whiskers.

The method for producing fiber-reinforced ceramics according to the present invention comprises at least one of titanium carbide whiskers, nitride whiskers and carbonitride whiskers,
It is a method of mixing at least one of diamond and cubic boron nitride or a raw material which is converted into them during the process, and sintering the mixture by applying a pressure of 1 GPa or more and a temperature of 1000 ° C. or more.

The present invention will be described in detail below. The diamond powder or cBN powder used in the present invention is itself composed of a single crystal or a polycrystal, and its average diameter is preferably 20 μm or less, particularly preferably 1 to 4 μm. If the average diameter exceeds 20 μm, the bending strength of the sintered body decreases. When the average diameter is 1 μm or less, mixing and the like become difficult and productivity decreases, but bending strength and the like tend to improve.
As a method for producing these powders, an ultra-high pressure synthesis method, a vapor phase synthesis method and the like are favorably used. Further, a raw material such as graphite, amorphous carbon or hBN which is converted into diamond or cBN by firing may be used. In this case, it is effective to use a known catalyst for promoting conversion.

The fiber-reinforced ceramics of the present invention contains diamond or cBN and at least one of titanium carbide whiskers, nitride whiskers or carbonitride whiskers, and the whisker content is 5-9.
A ratio of 5% by volume is desirable. If it is less than 5% by volume, the effect of improving the toughness is poor and the sintered body tends to be damaged.

If it exceeds 95% by volume, the abrasion resistance tends to decrease. The desired amount of whiskers depends on the application, but when used as a cutting tool, it is 30 to 6 when cutting steel.
0% by volume, 15-40% by volume for cutting cast iron, 50-95% by volume for heavy cutting, and 5-40% by volume for light cutting are desirable.

Further, it is desirable to contain 5% or more of whiskers having a diameter of 5 μm or less and an aspect ratio of 3 or more in the total amount of whiskers. 10 whiskers for practical use
% Or more, optimally 25% or more. When the diameter of the whiskers is 5 μm or less and the aspect ratio is 3 or more and less than 5%, the effect of improving the toughness decreases.

Further, the amount of oxygen in the above whisker raw material is 3
It is desirable that the content is not more than weight%.

This is because if the oxygen content in the whiskers is more than 3% by weight, the wear resistance is likely to decrease when used as a cutting tool. The optimum oxygen content is 1.5% by weight or less.

Further, the fiber-reinforced ceramics of the present invention is
It may contain diamond or cBN, a titanium compound whisker, and particles of at least one of titanium carbide, nitride, and carbonitride. The titanium compound particles are dispersed between diamond or cBN or whiskers to form diamond and cB.
It is possible to strengthen the bond of N particles and improve the toughness, hardness, strength and cutting performance. The particle size of the titanium compound particles is preferably smaller than the diameter of the whiskers and the particle sizes of cBN and diamond. This is to fill the gaps between the diamond and cBN particles and the gaps between them and the whiskers. These titanium compound particles partially produce TiC when they come into contact with diamond, and partially produce TiB ₂ and Ti when they come into contact with cBN.
N is generated and strongly bonded to each other. Therefore, the whiskers can improve the toughness and form a strong sintered body. 2% by volume of titanium compound particles in the total amount
It is desirable to contain the above. This is because if it is less than 2% by volume, the effect of improving strength, hardness, toughness, and cutting performance hardly appears. Titanium compound particles, especially 1 in the total amount
It is desirable to contain 0 to 25% by volume.

Further, according to the present invention, in addition to the above diamond or cBN and whiskers, at least one of aluminum nitride and titanium boride may be contained. This is because these have the effect of strengthening the bond between the whiskers or particles of the carbide, nitride or carbonitride of titanium and the diamond or cBN and improving the bending strength.
The content of aluminum nitride and titanium boride is 1 to 30.
Volume%, preferably 10 to 20% by volume.

In order to produce such fiber-reinforced ceramics, for example, at least one of whiskers made of titanium carbide, nitride and carbonitride, and at least one of diamond and cubic boron nitride, or Raw materials to be converted into them during the process and, if desired, at least one powder of titanium carbide, nitride and carbonitride, titanium, aluminum, nickel,
Cobalt and at least one powder of these compounds are mixed at a predetermined ratio and fired. If titanium, aluminum, nickel, or cobalt is added, the average diameter is 1
It is desirable to add as a metal powder or boride having a particle size of 0 μm or less.

After being crushed, it is molded into a predetermined shape. Examples of these molding means include a die press, a cold isostatic press, and extrusion molding.

It is desirable that the temperature and pressure during firing are selected as low as possible within the range that diamond and cubic boron nitride are not decomposed and a dense sintered body is obtained. During this firing step, there is a step of applying a pressure of 1 GPa or more and a temperature of 1000 ° C. or more to sinter. Here, the reason why the pressure is set to 1 GPa or more and the temperature is set to 1000 ° C. or more is to sinter in order to obtain a dense sintered body while suppressing decomposition of diamond or cBN. Ultra-high pressure synthesis method is applied to the firing. The firing is optimally performed at a temperature of 1200 to 1850 ° C., and may be performed in a reducing atmosphere in which an inert gas such as Ar or He or carbon is present.

[0018]

In the fiber-reinforced ceramics and the method for producing the same according to the present invention, the carbide carbide whisker, nitride whisker, and titanium carbide whisker in the component consisting of diamond and cubic boron nitride,
By including at least one kind of carbonitride whiskers, it becomes possible to improve toughness in addition to the good wear resistance originally possessed by diamond and cubic boron nitride. Further, by incorporating at least one kind of particles of titanium carbide, nitride and carbonitride in the fiber reinforced ceramic of the present invention, diamond, cBN,
Fill the gaps in the whiskers with titanium compounds (whiskers,
(Particles) are in contact with diamond, TiC, cB
At the portion in contact with N, TiB ₂ and TiN are generated and firmly bonded to each other, and further, toughness, hardness, strength and cutting performance can be improved.

Further, by containing 5% or more of whiskers having a diameter of 5 μm or less and an aspect ratio of 3 or more in the total amount of whiskers, it becomes possible to suppress the occurrence of voids and defects in the sintered body.

Further, a pressure of 1 GPa or more and 1000 ° C.
By sintering at the above temperatures, a dense sintered body can be obtained without decomposing cBN or diamond.

The present invention will be described below with reference to the following examples.

[0022]

【Example】

Example 1 Diamond or cBN powder having an average particle size of 1 μm or less and a purity of 99.9% or more and, if desired, predetermined raw material powders were weighed in the amounts shown in Table 1, and then mixed and ground in a rotary mill for 1 hour. A predetermined amount of titanium carbide, nitride, carbonitride whiskers (average oxygen content: 1 to 3% by weight) was added to this mixed powder, which was sealed with a nylon ball in a nylon pot and mixed for 1 hour in a rotary mill. It was The mixed slurry was dried as a raw material for firing, and this raw material was filled in a carbon mold and subjected to ultrahigh pressure firing at the temperature and pressure shown in Table 1 for 0.5 hour.

[0023]

[Table 1]

3 × 3 × 13 m for each sample obtained
Fracture toughness was measured by an indentation method at a load of 20 kg using a 3-point bending bending strength of m and a span of 10 mm, a micro Vickers hardness of a load of 1 kg, and a diamond indenter for Vickers hardness. In addition, a wear test was performed under the following cutting conditions using each sample containing cBN, and the flank wear amount after cutting was also performed, and the defect test was performed. Here, the case where there was no defect was marked as ◯.

(Abrasion test) Work material SKD11 Cutting speed 100 mm / min Cutting depth 0.5 mm Feed 0.1 mm / rev Cutting time 10 min (Fracture test) Work material SKD11 (with 4 grooves) Cutting speed 100 mm / min Cutting depth 0 .5 mm feed 0.1 mm / rev cutting time 10 min In the case of diamond, a wear test and a defect test were conducted by replacing the work material with an aluminum silicon alloy. The results of the characteristic evaluation are shown in Table 2.

[0026]

[Table 2]

According to Tables 1 and 2, the samples within the scope of the present invention have a strength of 58 kg / mm ² or more and a hardness of 27.8 GPa.
As described above, it is understood that the toughness is 7.4 or more and the cutting test also has excellent characteristics. The ratio of whiskers in Table 1 is the ratio of whiskers having a diameter of 5 μm or less and an aspect ratio of 3 or more to the total amount of whiskers.

Example 2 The present inventors made the same amounts of diamond, cBN, and firing conditions as in Example 1 above, and added titanium carbide, nitride and carbonitride powders as shown in Table 3. Then, the strength, hardness, toughness, wear amount and fracture resistance in the cutting test were measured in the same manner as in Example 1. The results are shown in Table 4.

[0029]

[Table 3]

[0030]

[Table 4]

According to Tables 3 and 4, the samples within the scope of the present invention have a strength of 65 kg / mm ² or more and a hardness of 30.0 GP.
a or more, toughness of 8.0 or more, and excellent characteristics in cutting test, and addition of titanium carbide, nitride, or carbonitride powder should improve the characteristics as compared with the case of not adding. I understand.

[0032]

As described in detail above, according to the present invention, at least one of titanium carbide whiskers, nitride whiskers, and carbonitride whiskers is used as a fibrous substance to be contained in diamond or cubic boron nitride ceramics. This reduces the reactivity with iron oxide and provides excellent wear resistance, toughness and strength, and can be used as a material for tools that can be used for all work materials, or for the use of fiber-reinforced ceramics for other machine parts. Can be expanded.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C22C 29/16

Claims (4)

[Claims] 1. A fiber reinforced ceramic containing at least one of diamond and cubic boron nitride and at least one of titanium carbide whiskers, nitride whiskers and carbonitride whiskers. 2. The fiber-reinforced ceramics according to claim 1, containing at least one kind of particles of titanium carbide, nitride and carbonitride. 3. Whiskers are contained in a proportion of 5 to 95% by volume, the diameter is 5 μm or less, and the aspect ratio is 3.
The fiber reinforced ceramics according to claim 1 or 2, wherein the above whiskers are contained in an amount of 5% or more in the total amount of whiskers. 4. A mixture of at least one of titanium carbide whiskers, nitride whiskers and carbonitride whiskers of titanium and at least one of diamond and cubic boron nitride or a raw material which is converted into them during the process,
A method for producing fiber-reinforced ceramics, which comprises sintering the mixture by applying a pressure of 1 GPa or more and a temperature of 1000 ° C. or more.