JPS63282166A - High-density metal boride-base sintered ceramics body - Google Patents

Abstract

PURPOSE:To form a sintered ceramics body which has excellent impact resistance and is useful for cutting tools by calcining a mixture prepd. by using >=1 kinds of borides of MB2 MB, M2B5 types (M is metal) and metal compd. for a binder as basic components, and adding a specific double carbide, carbonitride or double carbonitride. CONSTITUTION:This high-density metal boride-base sintered ceramics body has the following constitution: The sintered body of the mixture prepd. by using (A) at least one kinds selected from TiB2, ZrB2, CrB2, HfB2, VB2, TaB2, NbB2, MnB2, MoB2, YB2, AlB2, MgB2, CrB, VB, TaB, NbB, MoB, HfB, YB, ZrB, TiB, MnB, W2B5, and Mo2B5 and (B) at least one kinds among the cobalt boride, nickel boride and iron boride of the metal compd. for the binder as the basic components and adding >=1 kinds among the double carbide of Ti, Zr, Hf, W, and C or carbonitride or double carbonitride consisting of Ti, Zr, Hf, and C and N except TiCN at 0.1-10wt.% of the total weight to these components.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a novel metal boride-based ceramic sintered body having a high density and suitable as a cutting tool material, particularly a cutting tool for woodworking and a wear-resistant material. .

<Prior art> Until now, tungsten carbide has been mainly used as a cutting tool material, but due to the recent trend of raw material shortages, metal borides, such as titanium diboride, have been used as an alternative material. Sintered bodies have started to attract attention.

Incidentally, this metal boride sintered body has excellent heat resistance, oxidation resistance, strength and hardness at high temperatures, and is easily available in terms of resources. However, it has the disadvantage of low flexural strength.

In order to improve the sinterability and bending strength of such a metal boride sintered body, the present inventors proposed that various binders be added in advance, as disclosed in Japanese Patent Publication No. 56-41690,
Japanese Patent Publication No. 56-45984, Japanese Patent Publication No. 54-7277
No. 9, JP-A-56-23246, JP-A-56
-32379 Publication) Each achieved some degree of effectiveness, but research continued to further improve heat resistance, hardness, and bending strength.
The basic components are at least one selected from monoborides and diborides of metals such as Mo, Hf, and Zr, and at least one metal compound for a binder, and metal carbides and metal nitrides are added to the base ingredients. It has been found that a material prepared by blending selected additives and sintering exhibits even better physical properties (Japanese Patent Laid-Open No. 57-'42578). Although this material exhibits satisfactory physical properties as a wear-resistant tool, it lacks toughness and cannot be considered satisfactory as a woodworking cutting tool. Therefore, we developed ceramics to which titanium carbonitride was added (Japanese Patent Laid-Open No. 61-97169).

However, it is necessary to further improve impact resistance and expand its use as a cutting tool for a wide range of materials.

<Problems to be Solved by the Invention> An object of the present invention is to provide a metal boride-based ceramic having impact resistance that can be widely used as cutting tools and wear-resistant tools.

<Means for solving the problem> The present inventors have conducted extensive research in order to impart impact resistance to metal boride ceramics, and have found that in order to improve impact resistance, it is possible to improve impact resistance by simply increasing toughness. It was discovered that large grains and pores that cause defects must be removed. Therefore, an attempt was made to obtain a sintered body by producing a fine grained metal boride powder raw material, but the fine grained metal boride powder oxidizes easily and has more pores, making it impossible to improve impact resistance that much. There wasn't. Therefore, we searched for an additive that had an oxygen removal effect, and found that carbides and carbonitrides had this effect, and that double carbides and double carbonitrides had a remarkable oxygen removal effect, and they improved their impact resistance. It was confirmed that this can also be improved by removing oxygen, leading to the present invention.

That is, the present invention includes (A) one or more of MB2, MB, and JBr type borides (M represents a metal) and CB) cobalt boride and nickel boride as a metal compound for the binder.

The basic component is a mixture of at least one type of iron boride, and TiCN further contains (C) a double carbide consisting of Ti, Zr, Hf, W and carbon, and nitrogen.
0.1% by weight of carbonitrides and double carbonitrides, excluding carbonitrides
This relates to a high-density metal boride ceramic sintered body made of a sintered body of a mixture containing 10% by weight of .

The component (A) which is the main component of the present invention is TiB2, Z
rB2.

CrB2. VB2. TaB2. NbB2. Mn
Bz, MoB2. HfBz, YB2゜At' B
2. MgB2. Metal diborides such as ZrB2, C
rB.

VB, ZrB, TaB, NbB, MoB, old B
, YB, kl B, MgB and other metal-borides,
It is a metal boride selected from metal pentaborides such as W, B5 P Mo2B5.

These may be used alone or in combination of two or more.

Next, the metal compound for a binder used as component (B) is one that has been commonly used as a binder for conventional metal boride-based sintered bodies, such as COB, C02, etc.
B, Cobalt boride like GO3B, NiB.

These include nickel borides such as Ni2B, Ni3B, and Ni4B3, and iron borides such as FeB and Fe2B, and these may be used alone or in combination of two or more.

The amount of the metal compound for binder added is selected in the range of 0.1 to 10% by weight based on the total amount of the raw material composition.

If this amount is less than 0.1% by weight, it will not be sufficiently densified, and if it exceeds 10% by weight, the ceramic surface will sweat during sintering, so there is no point in adding any more.

In the present invention, it is necessary to add one or more types of double carbide, carbonitride, and double carbide to the basic component consisting of the components (A) and (B) described above.

This double carbide is composed of Ti, Zr, If, W and C, and the atomic ratio of the two metals is 1:
It is in the range of 9 to 9:1.

In addition, as double carbides, Ti, Zr, Hf, C and N
It is a double carbonitride consisting of and the atomic ratio of the two metals is 1.
:9 to 9:1, and the atomic ratio C/N of carbon to nitrogen is 1/9 to 9. This atomic ratio C
When /N is 179 or less, it becomes the same as double nitride. Moreover, when it is 9 or more, it becomes a double carbide, and the effect of addition is the same as that of a double carbide. Furthermore, for the two types of metals with a metal atomic ratio M>/Mz, those having an atomic ratio in the range of 179 to 9 are preferable.

In addition, carbonitrides include Zr and Hf carbonitrides,
The atomic ratio C/N of carbon and nitrogen is preferably in the range of 1/9 to 9.

Outside this range, the effect is similar to that of adding carbides or nitrides.

The ceramics of the present invention contain the above-mentioned components with an average particle size of 4 μm.
It is preferable to use a raw material that has been classified into particles of 2 μm or less, preferably 2 μm or less. Further, as a production method, a mixture of these raw material powders can be produced by the hitherto known hot pressing method, ordinary sintering method, or hot isostatic pressure sintering method.

For example, fill a mold with a raw material powder mixture and
It is cold compressed using a press pressure of approximately n/c+#, and then further molded using a rubber press under a hydrostatic pressure of approximately 05 to 10 ton/ei. Of course, it may be molded using either one, or may be molded by a slurry method. Next, the green compact thus obtained is heated at 13oo-2000°C, preferably 1400-170°C in vacuum or in a neutral or reducing atmosphere such as argon, hydrogen, carbon dioxide gas, etc.
Sinter at a temperature of 0° C. for 30-300 minutes. Furthermore, if necessary, a hot isostatic sintering method is used to heat the product under a pressure of about 2 ton/cd or less using argon gas or the like.
Sinter at 700°C for 5-300 minutes.

At this time, the continuous sintering process can be omitted by placing the green compact in a metal can.

After filling the raw material powder mixture into a mold such as a graphite mold,
In a vacuum or in a neutral or reducing atmosphere such as argon, hydrogen, or carbon dioxide gas, the die pressure is 50 to 30
Sintering can also be carried out using the so-called hot press method, in which heating and sintering is carried out at 0 kg/cd and a temperature of 1300 to 2000°C, preferably 1400 to 1700°C, for 10 to 200 minutes.

In this way, a metal boride-based ceramic sintered body suitable for various cutting tools is obtained.

<Example> Finely ground Ti'Bz, TaJ, CoB,
(TiBHf2)C powder was classified to a particle size of 4 μm or less using a classifier to obtain a raw material powder. 91% Ti
B2-6% TaB2-1% CoB-2% (T+gHfz
) were mixed at a composition ratio of C.

However, the ratio is a weight ratio. Such raw material powder was filled into a graphite die, and heated and sintered at 1500° C. for 60 minutes in a vacuum under a hot press pressure of 200 kg/ci/. The porosity of the obtained sintered body was 0.06vo 1%, and the U property value was 4 MP.
am'S.

The hardness was 2400Hv. This example is shown in NcL4 in Table 1.

Similar experiments were also conducted with other compositions.

The results are shown in Table 1. However, 1, 9, and 10 were shown as comparative examples.

<Effects of the Invention> According to the present invention, a porosity-free metal boride ceramic sintered body made from fine powder can be obtained, and can be used as a cutting tool or wear-resistant member with low impact resistance.

Claims (1)

[Claims] 1, (A) TiB_2, ZrB_2, CrB_2, Hf
B_2, VB_2, TaB__2, NbB_2, MnB
_2, MoB_2, YB_2, AlB_2, MgB_2
, CrB, VB, TaB, NbB, MoB, HfB, Y
At least one species selected from B, ZrB, HfB, TiB, MnB, W_2B_5 and Mo_2B_5,
(B) at least one of cobalt boride, nickel boride, and iron boride as a metal compound for binder as a basic component;
Add to this the total amount of (C) one or more types of double carbides consisting of Ti, Zr, Hf, W and C, or carbonitrides or double carbonitrides other than TiCN consisting of Ti, Zr, Hf, C and N. A high-density metal boride-based ceramic sintered body comprising a sintered body of a mixture to which 0.1% to 10% by weight is added.