JPS61270265A - High strength high tougness tib2 base composite sintered body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a Ti82 (titanium diboride) sintered body.

In general, metal boride ceramics have the characteristics of high melting point, high strength, high hardness, and high corrosion resistance, and have traditionally been used as materials for cutting tools, heat engine parts, etc., but titanium-based borons have not been put into practical use. It's a monster.

The TiB2 composite sintered body of the present invention has excellent characteristics such as high melting point, high strength, high hardness, electrical conductivity, high toughness, corrosion resistance, and oxidation resistance, so it can be used in cutting tools, heat-resistant materials, mechanical parts, electrical parts, etc. It is a material that can be widely used.

[Prior art] TiB2-Al2O:l, Ti, TiB2-Al2O:l, TiB2-based composite sintered bodies have been widely put into practical use for cutting tools.
Various B2-T1CN systems have been proposed in patents and the like.

That is, as a sintering aid or a subcomponent in a TiB2 sintered body such as a composite material, carbides such as Tie, he, SiC, and WC, nitrides such as TiN and TaN, carbonides such as T1CN, A I203 , ZrO2, etc. The oxide WB, I(
Borides such as fB2, NbR2, TaB2, various metals, etc. are known.

[Problems to be solved by the invention] For example, regarding carbides, Japanese Patent Publication No. 55-50918, Japanese Patent Publication No. 53-29843, and Japanese Patent Application Laid-open No. 50-111111
Ni-BaC, SiC in JP-A No. 57-27975, JP-A No. 49-85115, Ni-WG, and Patent Publication No. 38-2
4207, Tokuko Sho 3'l-9052, Tokuko Sho 52-2
125a' ToniTiC KaM Although shown, these carbides are used alone or in combination with other borides, metal nitrides, etc. These materials are mainly used as wear-resistant materials for tools and vapor deposition heaters, but they do not have sufficient strength, toughness, oxidation resistance at high temperatures, or wear resistance.

Next, there are nitrides such as TiN and TaN, but they are often used alone or in combination with other carbides and borides, and are used in tools and decorative materials, and are excellent in terms of high hardness and strength. is insufficient in terms of oxidation resistance and toughness,
Although TicN is disclosed in Japanese Patent Publication No. 58-18348, it has a drawback in oxidation resistance.

Borides are not used alone and are used in TiB2 series, T
It is generally used as an iC-based or TiN-based composite material. Additionally, metals are often used as sintering aids.

Among oxides, T 1B2-AI203 type tools are famous and have been put into practical use, but their toughness and oxidation resistance are insufficient.

In addition, vapor deposition heaters made of composite insulators such as BN and ALN have been put into practical use, but these are limited to use in a neutral atmosphere and are not intended as high-strength materials.

Furthermore, in these proposals, higher toughness, high strength and high hardness are required in order to be applied as tools and machine parts, and excellent oxidation resistance is also required for electrical parts and tools. Not obtained.

In view of these points, we have tried to solve the conventional problems with TiB2-based sintered bodies, which have excellent properties but are not fully utilized and are actually used only in extremely limited applications (tools, evaporation heaters). As a result of research aimed at overcoming this problem, we succeeded in developing a sintered body that has the following properties: high luminous intensity, high strength, high hardness, high toughness, oxidation resistance, corrosion resistance, and heat resistance, and has significantly improved some of these properties. It is something.

[Means for solving the problem] That is, the present invention uses TiB2 as a main component and has a weight percentage of 1 to 15%.
The gist is a high-strength, high-toughness TiBz-based composite sintered body characterized by containing 5% to 70% of TiC.

The TiB2 used in the present invention can be obtained, for example, by reacting a mixture of TiO2, B2O3 and C at high temperature, and it is preferable to use one with as high purity as possible for the production of this sintered body, and the particle size It is preferable to use a powder as small as possible, specifically a powder with a purity of 39% or more and an average particle size of 10L, especially 1IL1.
These are as follows.

As for SiC and TiC, which are present as subcomponents, it is sufficient that they are present in a predetermined amount as such compounds in the form of a sintered body, so they may be blended in any form as starting materials; If a raw material other than Tie is used, special consideration is required at the sintering stage, so it is best to prepare it as SiC or TiC as the usual blended raw material.

The raw materials for SiC and TiC are preferably as pure as possible, preferably 99% or higher.

The raw material mixture is usually prepared by uniformly mixing these three types of fine powders, but the same effect can be obtained by ultrafinely pulverizing them for the purpose of pulverizing and mixing. Generally, the particle size of the mixed raw material is preferably 1Op or less, and more preferably the average particle size is sufficiently adjusted to 4 or less. It is appropriate to use an SrC pole for pulverizing these particles.

The sintered body of the present invention can be obtained by filling a graphite mold with these mixtures and hot pressing in vacuum or in a neutral or reducing atmosphere such as argon or helium, or by rubber press molding the above mixture and firing at normal pressure. 50~2000kg/r
Sintering can be performed by firing under a pressure of about n'. If the material is hot-pressed or fired under normal pressure and then sintered and bonded under high temperature and pressure, a higher density sintered body can be obtained. The firing temperature is 1,600 to 2,200°C, and the firing time is usually about 0.5 to 5 hours, although it depends on the size of the sample.

In the sintered body of the present invention, SiC is required to be at least 1% by weight (the same applies hereinafter), because if it is less than that, the oxidation resistance will not be sufficient and it will be difficult to achieve high density.
On the other hand, if the amount is too high, it is not preferable because the original characteristics of TiB2 such as high strength, high toughness, high hardness, corrosion resistance, and heat resistance will deteriorate, so it is necessary to limit it to a maximum of 15%, and preferably 3 to 10%. It is.

Furthermore, it is necessary to contain at least 5% of TiC, because if it is less than that, a finely divided sintered body cannot be obtained and the desired high strength, high toughness, and high hardness cannot be obtained. As the strength decreases with growth, the oxidation resistance and corrosion resistance also decrease, so it is necessary to limit the BO% to a maximum of 70%, preferably 10 to BO%, and more preferably 30 to BO%.
It is 60%.

In addition, these SiC and TiC are required to be present in an alloy of at least 6% or more, preferably 10% or more, in the sintered body, because if these subcomponents are too small, a dense sintered body cannot be obtained. This is because the strength is low and the oxidation resistance and corrosion resistance are not sufficient.

The sintered body of the present invention consists of components other than these subcomponents, that is, the remainder substantially consists of TiB2, but it does not contain components other than TiB2, such as Bac, WC, and metals, to the extent that the characteristics of the neck 82 quality are not impaired. Fe, 84. Of course, there is no problem even if a small amount of Go or the like is included, but it is desirable to keep the amount as small as possible.

Furthermore, other components may be included as subcomponents within a range that does not essentially impair the intended effects of the sintered body of the present invention, or they must be kept in as small a quantity as possible, including unavoidable impurities.

The structure of the sintered body of the present invention is extremely dense in which fine crystals of TiB2, specifically, most crystals of 5 tons or less are uniformly dispersed, and the peripheral component is that the fine crystals of TiB2 are distributed between grains. It consists of good tissue distributed in the area.

[Effects of the Invention] The sintered body of the present invention thus obtained has high density, high strength, high hardness, high toughness, and is a conductive sintered body with excellent corrosion resistance and oxidation resistance. Applicable to cutting tool wear-resistant materials, mechanical parts, electrical parts, corrosion-resistant parts, etc.
It can be used for various purposes that exhibit the characteristics of the B2 quality sintered body, and its practical value is great.

Examples] Example 1 TiB2 powder (purity 89% or more) Tie powder (purity 9
A bot mill was used to sufficiently mix and grind the SiG powder (purity of 98% or more) and SiG powder (purity of 98% or more), and the mixture was ground and mixed for 3 days using a SiC pole in an ethanol solvent. Remove alcohol from the obtained powder using an evaporator and dry thoroughly.
A powder with an average particle size of 0.15 IL was obtained. This powder was filled into a graphite mold and heated at 350 kg/crn' (
7) Heated under pressure at 1900"C-t' for 80 minutes to obtain a sintered body. The physical properties of the obtained sintered body are shown in Table 1 as sample No.
I'm setting it as 1.

In addition, the structure of this sintered body is good, and the average particle size of TiB is 3 μm.
It had an extremely dense crystal structure in which 2 fine crystals were uniformly dispersed and subcomponent Tie and SiG crystal grains existed between the TiB2 crystal grains.

Examples 2 to 9 and Comparative Example 10.11.12 Table 1 shows the results for each sample prepared by preparing the predetermined blended raw materials in almost the same manner as in Example 1 and treating them under the predetermined firing conditions. show.

Note (1) Fracture toughness values were determined by the chevron notch method.

Note (2) Oxidation resistance indicates the oxidation status under the conditions of 1000°C and 12 hours in an oxidizing atmosphere.

Note (3) Corrosion resistance to AI was evaluated after the reactivity of the AI grain powder was brought into contact with the powder at 1200° C. for 2 hours in a vacuum atmosphere.

Claims (4)

[Claims] (1) TiB_2 as the main component and 1 to 15% S by weight
A high-strength, high-toughness TiB_2 composite sintered body characterized by containing iC and 5 to 70% TiC. (2) The sintered body according to claim 1, which contains 10% or more of SiC and TiC in total. (3) The sintered body according to claim 1, containing 3 to 10% SiC and 10 to 60% TiC. (4) Claim 3 in which TiC is 30 to 60%
The sintered body described in section.