JPS6163573A - High corrosion resistance zrb2 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 Application Field] The present invention relates to a ZrBz (zirconium diboride) sintered body.

In general, metal boride ceramics have the characteristics of high melting point, high hardness, high strength, and high corrosion resistance, and have traditionally been used as cutting tools and heat engine parts materials, but although they have not been put into practical use yet. Most of them are titanium borides, and the reality is that zirconium borides are hardly ever put into practical use.

The Zr1h composite sintered body of the present invention has excellent characteristics such as high melting point, high strength, high corrosion resistance, high hardness, electrical conductivity, and oxidation resistance, so it can be used as high temperature corrosion resistant parts, mechanical parts, heating elements, electrodes, and inductors. It is a material that can be widely used for furnace crucibles, etc.

[Conventional technology]

Currently, there are almost no ZrBz composite sintered bodies that are in widespread practical use, but various ones have been proposed in patents and the like.

That is, in ZrB* sintered bodies such as sintering aids or composite materials, subcomponents include silicides such as 10812 and TaN.
, HfN + BN and other nitrides, ZrO2 and other oxides, Sin, B4C and other carbides, and various metals are known.

[Problem that the invention seeks to solve]

For example, regarding silicides, ZrB
lx, and Mo5iz in U.S. Patent No. 3,705,112.
However, since these 81-series compounds melt or decompose during sintering in a high-temperature atmosphere, their structures are often porous and the crystal grain growth becomes large, resulting in poor strength and corrosion resistance. It is often insufficient, and its oxidation resistance is also 51.
02 is expected to be effective as a film, but these subcomponents alone are not sufficient for use in air.

Next, regarding nitrides, TaN disclosed in U.S. Patent No. 3,305,374 is used as a high hardness material, Zr1h,
It is added to TiBz, etc. and applied to tool materials and decorative materials, and although it is excellent in terms of high hardness and high strength, it is used in high-temperature oxidizing atmospheres such as high-temperature corrosion-resistant parts, heating elements, electrodes, and induction furnace crucibles. In some cases, oxidation resistance, spalling resistance, corrosion resistance, etc. are insufficient.

Next, regarding carbide, U.S. Patent No. 3775137jC
8i0. Although B4C and SiC are disclosed in U.S. Patent No. 3,325,300, the addition of SiC in U.S. Pat. No. 3,775,137 is insufficient in terms of oxidation resistance; Mo8
When 1g+810+B4C is added, 51g of Mo has a melting point lower than the sintering temperature and melts during sintering, decomposes, promotes grain growth, and makes the structure porous, making it difficult to achieve high density. Therefore, it has not yet reached the level of material that is particularly required as a high-temperature structural member.

In view of these points, the present inventors added E+10+B40 without first walling MoSi2, or added 810+
ZrB was improved by studying the addition of BN.
We succeeded in obtaining a Z sintered body. These are Z in their own way
Although it made it possible to put rB2 sintered bodies to practical use,
It was also true that there was still room for improvement.

For example, SiC! + The BN addition system was satisfactory in that spalling resistance could be improved by increasing the BN content, but adding BN, which is difficult to sinter, made it possible to improve dense sintered bodies. It is difficult to obtain this, and the strength and hardness are not necessarily sufficient (therefore, it cannot be said to be suitable for applications such as high-temperature, high-strength parts).

Furthermore, although the B1C + B4C additive system was satisfactory in terms of strength, hardness, and oxidation resistance, it was not necessarily sufficient in terms of spalling resistance and corrosion resistance, especially corrosion resistance against iron and slag. Therefore, it cannot necessarily be said that it is suitable for applications such as spall-resistant and high-temperature corrosion-resistant members for steel, etc.

In view of these points, ZrB2 sintered bodies, which have excellent properties but are not fully utilized and are actually used only in extremely limited applications, have been polished to overcome the conventional problems. As a result of progressing in this process, it has achieved various properties such as high density, high strength, oxidation resistance, corrosion resistance, and even spalling resistance, and has significantly improved some of its characteristics, especially high-temperature corrosion resistance as a reciprocating combination. They succeeded in developing an improved sintered body.

[Means to solve the problem]

That is, the present invention contains Zr1lh as a main component, TiN, Boo, and 5ill as subcomponents, each of which is at least 1 inch by weight, and the total amount of these subcomponents is 1.
The gist of the invention is a ZrBz composite sintered body having a high corrosion resistance of 0 to 50 degrees.

ZrBz used in the present invention is, for example, zirconium oxide,
It is obtained by reacting a mixture of boron oxide and carbon at high temperature, and it is preferable to use a powder with as high purity as possible for the production of this sintered body, and a powder with a particle size as small as possible is preferable. .

Specifically, it has a purity of 99 cm or more and an average particle size of 10 μm or less, especially 1 μm or less.

Furthermore, regarding the presence of Mero-Sin, B40, and TiN as subcomponents, it is sufficient that they are present in a predetermined amount as such compounds in the form of a sintered body, so it is not necessary to mix them in any form as starting materials. However, Sin
! If raw materials other than B4C and Ti2Jμ are used, special consideration is required at the sintering stage, so it is usually best to adjust the raw materials as Sin, B<C and TiN.

This 810. The B4C and TiN raw materials are preferably as pure as possible, and are usually 99% or higher.

The raw material mixture is usually prepared by uniformly mixing these three kinds of fine powders, but the same can be done by pulverizing MgI for the purpose of pulverizing and mixing. Generally, the particle size of the mixed raw material is 10 Am.
The average particle size should preferably be adjusted to 1 μm or less.

It is appropriate to use SiO balls for pulverizing these.

The sintered body of the present invention can be produced by filling these mixtures into a graphite mold, for example, and hot pressing in a vacuum or a neutral or reducing atmosphere such as argon, helium, or carbon oxide, or by molding the above mixture with a rubber press. It can be sintered by firing it under normal pressure.

The firing temperature was 1,700 to 2,200°C, and the firing time was O.
, S~3 hours is appropriate.

TiN, B4C, and aid as subcomponents each require 1% or more (wt%; the same applies hereinafter);
If iN is less than 1 inch, the characteristics of high corrosion resistance will not be fully exhibited, and B
If 4C is less than 1%, it is difficult to achieve high density, and if SiQ is 1% or less, it is difficult to achieve high density.
This is because the oxidation resistance is not sufficient if it is less than 100%.

In addition, the subcomponents Tie, B4C3 and Eii, O
If there is too little coalescence, the corrosion resistance and oxidation resistance against iron and slag will be insufficient, and a high-density sintered body will not be obtained, so a total amount of at least 10 pieces is required. It is.

On the other hand, it is possible for each of τiN, BaQ, and SiO to exist in the sintered body up to a half molecule ks degree, but when TiN exceeds approximately 50 degrees, the oxidation resistance decreases, and when B10 exceeds approximately 50 degrees. If it exceeds the temperature, the heat resistance and corrosion resistance will be poor.
If SiC exceeds about 50%, the spalling resistance effect will no longer be exhibited, which is undesirable, and in any case, ZrB
In order not to essentially impair the Z-quality characteristics, TiN and B4C are required.
It is necessary to limit the total amount of SiO and SiO to 50%.

In addition, in these ranges, a more desirable range is T
Each of iN, B4C, and SiO should be 3 or more and the total amount should be 10 or more, preferably 20Ls or more and up to 40%.

Further, the preferable range of each of the subcomponents is that TiN is 3
~15%, BiC from 3 to 25%, and SiC from 3 to 30%.

In the sintered body of the present invention, the components other than these subcomponents, that is, the remainder of the main component, is substantially composed of ZrBz, but the characteristics of the ZrBz material (without ZrBz)
Of course, there is no problem even if a small amount of other components such as TiBz are included as part of the main component, but it is desirable to keep the amount as small as possible.

In addition, it is of course possible to include other components as subcomponents as long as they do not essentially impair the intended effects of the sintered body of the present invention, but they should be kept in as small a quantity as possible, including unavoidable impurities. is necessary.

The sintered body of the present invention has a dense structure in which the main component is ZrB2 crystals, with TiN, B4C, and EliO strongly bonded between them, and the ZrBx crystals are extremely fine crystals. It exists and has come to demonstrate its characteristics to the fullest.

Specifically, most of the ZrB crystals in the sintered body of the present invention exist with a grain size of 10 μm or less.

〔Effect of the invention〕

The thus obtained sintered body of the present invention has high density, high hardness, high strength, high oxidation resistance, and is particularly excellent in high-temperature corrosion resistance, so it can be used as a high-temperature structural member and a high-temperature corrosion-resistant member. It is preferably applicable to ZrBz, etc.
It can be used for various purposes that exhibit the characteristics of a high-quality sintered body, and its practical value is great.

〔Example〕

Example I ZrB* powder (purity 99% or higher) 75 parts by weight, TiN powder (purity 99%) 10 parts, B40 powder (purity c+c+%)
) and 5 parts of SiO powder (purity 99%) were thoroughly mixed and ground using a bot mill in an ethanol solvent.
The mixture was ground and mixed for 3 days using an iO ball. The obtained powder was thoroughly dried by removing alcohol with an evaporator to obtain a powder with an average particle size of 0.15 μm. This powder was filled into a graphite mold and heated at 1900° C. for 30 minutes under a pressure of 350 Kty/cd in an argon atmosphere to obtain a sintered body.

The characteristics of the obtained sintered body are a relative density of 98% and a bending strength of 72%.
47 mj, no change in oxidation resistance (Note 1), no corrosion resistance to pure iron and slag (Note 2), hardness 2100 Kq/
-It was.

In addition, the size of the ZrBz crystal in this sintered body is mostly 5 μm or less, and there is Ti around the ZrBz crystal.
It had a dense structure in which N, B4C, and 8i0 were strongly bonded.

Table 1 shows the properties of the sintered body thus obtained.

Note 1) Oxidation resistance indicates the oxidation status under the conditions of 1000"c x 12m in an oxidizing atmosphere.

Note 2) Agility was determined from the thickness of the altered layer that formed the agility of the sample after adjusting the sample to 1 m square, embedding it in pure iron or slag, and treating it at 1500°C for 2 hours. In addition, the agile experiment was measured under an argon atmosphere.

Examples 2 to 6 and Comparative Examples 1 to 4 Table 1 shows the results for each sample obtained by adjusting predetermined mixed raw materials according to Example 1 and processing them under predetermined firing conditions.

Claims (5)

[Claims] (1) ZrB_1 is the main component, TiN is the subcomponent,
At least 1% each of B_4C and SiO by weight
A ZrB_2 composite sintered body having high corrosion resistance and containing the above and the total amount of these subcomponents is 10 to 50%. (2) The sintered body according to claim 1, wherein the subcomponents of TiN, B_4C, and SiC are all 3% or more by weight. (3) 3-15% TiN and 3-2% B_4C by weight
The sintered body according to claim 2, wherein the SiO content is 3 to 30%. (4) The sintered body according to any one of claims 1 to 3, wherein the total amount of TiN, B_4C, and SiC is 20 to 40% by weight. (5) The sintered body according to any one of claims 1 to 4, wherein most of the ZrB_2 crystals have a grain size of 10 μm or less.