JP3051603B2 - Titanium compound sintered body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber-reinforced ceramic containing a fibrous substance such as a whisker, and more particularly, to a titanium having high toughness and particularly suitable for cutting tools and other wear-resistant parts and decorative materials. The present invention relates to a compound sintered body.

[0002]

2. Description of the Related Art Conventionally, titanium carbide (TiC)
Although applied to various cutting tools and industrial machine parts as a main raw material of cermet materials, it has a drawback of poor toughness, which hinders the expansion of application fields. Therefore, conventionally, metals such as nickel and cobalt have been added to improve toughness.

[0003]

However, since metals such as nickel and cobalt have low hardness, they tend to increase the amount of wear as compared with materials containing no such metals. In addition, in the field of decorative articles, the added metal may cause allergy to the skin.

Furthermore, recently, attempts have been made to improve toughness by using acicular crystal grains (whiskers). A representative one is a SiC whisker, and much research has been conducted. Titanium compound whiskers have also been proposed for toughening, but have not yet been sufficiently studied in terms of the properties such as flexural strength, toughness, and hardness of ceramics, and at present have not reached a practical level. Was.

[0005]

Means for Solving the Problems The present inventors have conducted detailed studies on the above-mentioned whisker-based titanium compound ceramics, and as a result, have found that this material and the periodic table Nos. 4a, 5a,
The present inventors have found that by compounding at least one of carbides, nitrides, carbonitrides, and oxides of Group 6a elements, it is possible to improve mechanical properties such as fracture toughness.

That is, the titanium compound sintered body of the present invention comprises a total of 45% of a titanium compound whisker of at least one of titanium carbide, nitride, boride and carbonitride, and a titanium compound other than the whisker. To 97% by volume, the titanium compound whisker being contained in a proportion of 5 to 70% by volume in the total amount, and further containing at least one of molybdenum carbide and zirconium carbide in a proportion of 3 to 15% by volume. Features.

The titanium compound whiskers used in the present invention are themselves made of single crystal or polycrystalline, and have an average diameter of 3 μm or less, especially 0.5 to 1 μm.
It is preferred that When the average diameter is 3 μm or less, high bending strength can be maintained. When the average diameter is too large, it is difficult to uniformly disperse, and the strength and toughness tend to vary, and when used as a cutting tool. This is because the boundary wear of the flank increases. When used as a cutting tool, a single layer or two or more layers of Group 4a elements of the periodic table and Al carbides, nitrides, A surface coating layer made of at least one of carbonitride and oxide may be formed.

On the other hand, if the aspect ratio expressed by the major axis / minor axis of the whiskers is too small, the effect of fiber reinforcement is small, and high toughness cannot be obtained. Conversely, if the aspect ratio is too large, it is difficult to handle as a raw material and uniformly dispersed. It is difficult to obtain high toughness due to the inability to do so. Therefore, those having an average aspect ratio of 3 to 100, especially 10 to 30 are preferably used.

Such a titanium compound whisker can be synthesized, for example, by a CVD method, but any whisker produced by any method can be used.

This titanium compound whisker has a total content of 5%.
７０70% by volume, particularly 10 to 50% by volume, more preferably 20 to 45% by volume. The whisker amount was set to the above range because the whisker amount was 5% by volume.
If it is less than 70%, the effect of improving the toughness by adding whiskers is small, and if it exceeds 70% by volume, the sinterability of the entire system is reduced. In order to facilitate sintering and reduce the cost required for sintering, the addition amount of TiC whiskers is preferably 5 to 45% by volume, and most preferably 10 to 30% by volume. It is desirable that the titanium compound whisker be contained in an amount of 48 to 70% by volume in order to improve toughness.

In the present invention, the titanium compound whiskers are preferably TiC whiskers, and the titanium compound other than the whiskers is preferably mainly TiN. In addition, the titanium compound whisker Ti
It is desirable to contain 40 to 70% by volume of C whiskers, 2 to 15% by volume of TiN as a titanium compound, and 3 to 15% by volume of at least one of molybdenum carbide and zirconium carbide.

According to the present invention, Al ₂ O ₃ may be contained in an amount of 45% by volume or less. This is because Al ₂ O ₃ has an effect of improving wear resistance when this material is used as a cutting tool. That is, if the content of Al ₂ O ₃ is more than 45% by volume, the toughness of the sintered body decreases, and chipping easily occurs when used as a cutting tool. The added amount of Al ₂ O ₃ is preferably at least 20% by volume, particularly preferably at least 35% by volume. In the case where alumina is contained, it is desirable that a part of the titanium compound, TiN, be present inside the Al ₂ O ₃ particles.

According to the present invention, Ni and Co and at least one of oxides, carbides and nitrides thereof may be contained at 5% by volume or less. This is because Ni, Co and their oxides and carbides are TiC whiskers and Al ₂
This is because there is an effect of firmly binding O ₃ . Also,
The addition of Ni and Co improves the sinterability of the material. Ni, C
o and the amount of oxides, carbides and nitrides thereof
In particular, the content is preferably 0.5 to 2% by volume.

In the present invention, the periodic table 4a, 5
At least one of carbides, nitrides, carbonitrides and oxides of elements a and 6a should be contained in an amount of at least 3% by volume, especially at least one of molybdenum carbide and zirconium carbide should be contained in an amount of 3 to 15% by volume. Is preferred from the viewpoint of improving hardness and toughness. If it is less than 3%, the fracture toughness, hardness and strength of the sintered body tend to decrease.

When the matrix for dispersing the whiskers is mainly composed of Al ₂ O ₃ , it is preferable to mix titanium nitride. Titanium nitride is a particle having a diameter of 1 μm or less, and when at least a part thereof is present in the Al ₂ O ₃ particle, the effect of adding titanium nitride is large from the viewpoint of improving fracture toughness and bending strength. In order for titanium nitride to be present inside the Al ₂ O ₃ particles, it is important to control the rate of temperature rise during sintering and the particle size of the titanium nitride. For example, 1000
When the average particle diameter of titanium nitride is 1 μm or less, the temperature rise rate up to 1800 ° C. is 6 ° C./min or more and the average particle diameter is 0.5 μm.
m or less, it is particularly important that the temperature be 3 ° C./min or more.

When aluminum oxide is contained, a known oxide may be added as a sintering aid. By adding a small amount of oxide, sinterability as a matrix component can be increased, and characteristics can be improved. However, if the amount of this auxiliary agent is too large, the toughness of the sintered body decreases. Therefore, these sintering aids are preferably added at a ratio of 0.1 to 5% by weight, particularly 0.5 to 3% by weight based on the total amount. The oxide used here is Yb, Nd, Er, C
oxides such as e, Sm, Gd and Dy.

In order to manufacture the titanium compound sintered body of the present invention, titanium carbide, nitride and carbonitride titanium compound, titanium compound whisker, periodic table 4
a, 5a, 6a group carbide, nitride, carbonitride, oxide, aluminum oxide, Ni, Co, Cr oxide;
Carbide, if necessary, mixing sintering aid in the ratio described above,
After pulverization, desired molding means, mold press, extrusion molding,
After molding by injection molding, cold isostatic pressing or the like, baking is performed.

For the firing, ordinary firing, hot pressing, hot isostatic pressing, or the like is applied. At a temperature of 1650 ° C. to 1850 ° C., a reducing atmosphere containing an inert gas such as Ar or He or carbon or the like is used. The operation is performed in such a pressurized or reduced pressure atmosphere for 0.5 to 6 hours. In particular, in order to obtain a high-density sintered body, a sintered body having a theoretical density ratio of 96% or more may be prepared by ordinary firing or hot pressing, and the sintered body may be further subjected to hot isostatic firing. .

[0019]

In the present invention, the toughness of the sintered body can be improved by remarkably exhibiting the effect of extracting the whisker of the titanium compound. Also, by using a titanium compound or a titanium compound whisker, the wear resistance as a cutting tool and the color tone as a decorative material can be improved.

Hereinafter, the present invention will be described with reference to the following examples.

[0021]

EXAMPLES First, as starting materials, titanium compound powder, powders of elements of Groups 4a, 5a and 6a of the periodic table, Al ₂ O ₃ powder having an average particle diameter of 1 μm or less and a purity of 99.9% or more, and others were used. Was prepared, weighed at the ratios shown in Tables 1 and 2, and then mixed and pulverized for 12 hours with a rotary mill. A predetermined amount of a titanium compound whisker having an average particle diameter of 1 μm and an aspect ratio of 10 to 30 was added to the mixed powder, and the mixture was mixed by a rotary mill for 12 hours. The slurry after mixing was dried to obtain a raw material for hot pressing.

[0022]

[Table 1]

[0023]

[Table 2]

This raw material is filled in a carbon mold and 1750
Hot press firing was performed at a temperature of 500 ° C. and a pressure of 500 kg / cm ² to prepare a bending test piece based on JIS standards.

Each of the obtained samples was polished to a load of 20 kg.
Hardness and the toughness (K _1C ) were measured by the IM method after polishing to a mirror surface. The structure was observed from a micrograph to evaluate the sinterability. Tables 3 and 4 show the results.
Shown in

[0026]

[Table 3]

[0027]

[Table 4]

According to Tables 3 and 4, when the whisker addition amount is large (samples Nos. 1, 7, 18), the toughness is low because the hardness is low and the mirror finish is impossible due to the low density. Measurement was not possible and voids were generated. When no whisker was added (Sample No. 23), the toughness was extremely low. When no elemental compound of Groups 4a, 5a and 6a of the periodic table was added (Sample Nos. 7, 11, 1)
9) shows that the hardness is low.

On the other hand, it can be seen that all the samples prepared according to the present invention have excellent toughness and hardness.

[0030]

As described above in detail, the titanium compound sintered body of the present invention contains a titanium compound, a titanium compound whisker, and at least one of molybdenum carbide and zirconium carbide. The drawing effect can be remarkably exhibited, and the toughness and hardness of the sintered body can be improved. Also, by using a titanium compound or a titanium compound whisker, the wear resistance as a cutting tool and the color tone as a decorative material can be improved. Thereby, a titanium compound sintered body suitable for cutting tools, other wear-resistant parts, and decorative materials can be obtained.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ identification code FI C04B 35/81 C04B 35/56 ST (58) Field surveyed (Int.Cl. ⁷ , DB name) C04B 35/80 C04B 35 / 56-35/58

Claims (1)

(57) [Claims] 1. A whisker of at least one titanium compound selected from the group consisting of carbides, nitrides, borides and carbonitrides of titanium, and a titanium compound other than the whiskers of 45 to 9 in total.
7% by volume, the titanium compound whisker is contained at a ratio of 5 to 70% by volume based on the total amount, and further, at least one of molybdenum carbide and zirconium carbide is 3 to 15%.
A sintered body of a titanium compound, characterized in that the sintered body is contained in a ratio of volume%.