JPS6172688A - Electroconductive zrb2 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 (a) Field of Application of Tojo The present invention relates to a ZrFh (2R zirconium) composite sintered body.

In general, total boride ceramics have the characteristics of high melting point, high hardness, high strength, and high corrosion resistance, and have traditionally been used as materials for cutting tools and heat engine parts, but have never been put into practical use. The reality is that most of these are titanium borides, and zirconium borides are hardly ever put into practical use. - The ZrBz composite sintered body of the 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 a high temperature corrosion resistant member 1 mechanical member, heating element, FL
It is a material that can be widely used for electrodes, induction furnace crucibles, etc.

(Prior Art) Currently, there are almost no ZrB2 composite sintered bodies that are in widespread practical use, but various ones have been proposed in patents and the like.

That is, silicides such as MoSi2, TaN,
Nitrides such as HfN and BN, oxides such as ZrO2, carbides such as SiC and 84C, and various metals are known.

(Problems to be solved by the invention) For example, regarding silicides, ZrS
i2 is also known as U.S. Pat. No. 3,705,112 MoSi2
However, these Si-based compounds often have a porous structure that causes large crystal grain growth because they melt or decompose when sintered in a high-temperature atmosphere. The properties are often insufficient, and the oxidation properties are also 5.
Although iQ2 is expected to be effective as a film, it is not suitable for use in air due to these subcomponents alone.

Next, regarding nitrides, TaN disclosed in U.S. Pat. No. 3,305,374 is used as a high-strength material, and
, Ti82, etc., and is applied to tool materials and decorative materials, but it is superior in terms of high hardness and high strength.It is used in high-temperature oxidizing atmospheres such as high-temperature corrosive parts, heating elements, electrodes, and induction furnace crucibles. # Insufficient oxidation resistance, spall resistance, corrosion resistance, etc.

Next, regarding carbides, U.S. Patent No. 3775137
ic, U.S. Patent No. 3325300 NiBaC and SiC
has been disclosed, but US Pat. No. 3,775,137
Addition of only SiC is insufficient in terms of oxidation and A4J
Matabe3325300 ノMoSi2 +3a C,Mo
Si2 + S: With the addition of C*B, c, MoSi2 has a low melting point depending on the sintering temperature, and it melts during sintering, decomposing, and promoting grain growth, making the structure porous. Therefore, it is not a material that is particularly required for high-temperature structural members.

In view of these points, the present inventors added SiC+84G without adding MoSi2 first, or added SiC÷84G without adding MoSi2 first.
ZrB studied and improved with 8N added
We succeeded in obtaining a two-quality composite sintered body.

Although these methods have made it possible to put ZrB dual composite sintered bodies to practical use, it is also true that there remains room for improvement.

For example, the addition system of SiC + Ba C was satisfactory in that spalling resistance could be improved by increasing the BNN content; However, it was not always possible to obtain a solid body with sufficient strength and hardness, and the material was not suitable for use as a high-temperature, high-strength member.

In addition, the addition system of SiC + Ba C has 1 strength, hardness and #
Although it was satisfactory in terms of oxidation resistance, etc., it was not necessarily superior in terms of spall resistance, corrosion resistance, variable conductivity, etc., and therefore it could not be said to be suitable for applications such as corrosion-resistant parts for steel etc. It was something.

In view of these points, we are conducting research to overcome the conventional problems with ZrB2 sintered bodies, which have excellent properties but are not fully utilized and are actually used for only extremely limited applications. As a result of this progress, we have developed a sintered product that combines various properties such as high density, high strength, oxidation resistance, corrosion resistance, especially variable conductivity (TL resistance), and spall resistance, and has significantly improved some of its characteristics. This was a successful development of the structure.

(Means for solving the problem) That is, the present invention uses ZrB2 as a main component, and has a concentration of 1 to 1
5% S+C, 5-20% 84C and 3-40% A
The gist is a conductive ZrB7 composite sintered body characterized by containing I and N.

ZrB2 used in the present invention is, for example, zirconium oxide,
It is obtained by reacting a mixture of ljl oxide and carbon at high temperature, and it is preferable to use one with the highest purity in the production of this sintered body, and the particle size is also as small as possible. Powders are preferred.

Specifically, the purity is 99% or more, the average particle size is 10 pm, especially 1
This includes those with a diameter of 7 tm or less.

SiC and ALN are also present as subcomponents.

As for BN, it is sufficient that a specified number of such compounds exists as a sintered body, so it is not clear what form it can be blended as a starting material, and raw materials other than SiC, BN, and ALN. When using a special I! during the sintering stage. To! 1. SiC and BN are usually used as blended raw materials.

It is better to adjust it as ALN.

The raw materials for SiC, ON, and ALN are preferably as pure as possible, preferably 89% or higher.

The raw material mixture is usually prepared by uniformly combining these three kinds 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 mixed raw materials is 10 l■
The following is necessary: Preferably, the average particle diameter is sufficiently adjusted to 1 μm or less.

It is appropriate to use a SiC pole to crush these particles.

The sintered body of the present invention is prepared by filling a mixture of these into a graphite mold, for example, in a vacuum or in argon or helium.

- It can be obtained by hot pressing in a neutral or orphan atmosphere such as carbon oxide, or by rubber press molding the above mixture and then firing at normal pressure. Note that the firing temperature is 1800 to 2300°C, and the firing time is usually about 0.5 to 5 hours, although it depends on the size of the sample.

In the uninvented sintered body, 5 inches (silicon carbide)
is required to be at least 11% in ball weight percentage (hereinafter the same), 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 it is too high, the spall resistance and Since the effect of high corrosion resistance is not exhibited, it is undesirable to limit the content to a maximum of 15%, and preferably 3 to IQ%.

B, C: (polon carbide) must be at least 5%, because if it is less than that, it will be difficult to achieve high density.On the other hand, if it is too much, the heat resistance will decrease or the oxidation resistance It is undesirable to limit the content to a maximum of 20%, as the properties deteriorate, and the preferable range is 7 to 15%.

ALN (aluminum nitride) requires at least 3 z, but if it is more than that, it has low electrical resistance and cannot fully demonstrate its characteristics as an electrical component such as a heating element. Since the resistance becomes large and the characteristics of an electric member such as a heating element cannot be obtained, it is undesirable and needs to be kept at a maximum of 40%, and is preferably 5 to 30%.

In addition, the total amount of these SiC, B, G, AL, and N is required to be at least 8z, and it is possible to have them present up to about 60%, but if the total amount is too large, ZrB2 will decrease accordingly. Since this will impair the properties, a total amount of 15 to 50% is usually appropriate.

In the sintered body of the present invention, components other than these subcomponents, i.e., the remainder, essentially consist of ZrB2, but components other than ZrB2, such as T, may be added to the extent that the characteristics of ZrB2 are not impaired.
Of course, there is no problem even if there is a small amount of i87 etc., but it is desirable to keep it to a small amount as much as possible.

In addition, it is of course possible to include other components as subcomponents as long as they do not impair the intended effect of the sintered body of the present invention in terms of wood quality, and should be kept to a minimum including unavoidable impurities. It is necessary.

In the structure of the sintered body of the present invention, Zr82a fine crystals consisting of 11 grains with an average grain size of IJ are uniformly dispersed.

A as a subcomponent around the ZrB2 crystal grains and between the delivered grains.
It had a fine structure in which LN, Ba C, S, i(:) were distributed.

(Effects of the Invention) The sintered body of the present invention thus obtained has high density, high hardness, high strength, and is a multi-edible sintered body with excellent conductivity and dispersibility. High temperature structural parts, high temperature corrosion resistant parts,
It can be preferably applied to electrical components such as heating elements, and can also be used in various other applications that exhibit the characteristics of the ZrB dual composite sintered body, so its practical value is great.

(Example) Example 1 Zr Nichido powder purity 98% or more), 84G powder (purity 1
33% or more), ALN powder (purity of 99% or more), and 81C powder (purity of 99% or more) were pulverized and mixed for three days using a bot mill using SiC balls in an ethanol solvent in order to sufficiently mix and grind them. The obtained powder was thoroughly dried by removing alcohol with an evaporator, and the average particle size was 0.
15 g of powder was obtained. Using a rubber press, apply this powder to
000kg/cn (formed under argon atmosphere, 23
It was baked at normal pressure at 00°C for 2 hours. The properties of the sintered body thus obtained are shown in Table 1.

Example 3 The same ZrB2 powder, SiC powder, B4C powder, and ALN powder as in the actual construction were pulverized and mixed in a pot mill for 3 days using a 51C pole in an ethanol solvent.

Alcohol was removed from this powder using an evaporator and the powder was dried for several minutes to obtain a powder with an average particle size of 0.15. This powder was filled into a graphite mold and heated at 2050° C. for 30 minutes while pressurized to 350 kg/c+d in an argon atmosphere. Table 1 shows the properties of the sintered body thus obtained.

Examples 2 and 4 to 6 and Comparative Examples 7 to All 11 Predetermined blended raw materials were prepared according to Examples 1 and 3 and processed under predetermined firing conditions. Results for each sample are shown in Table J1.

Note 1) #Oxidizing property is under oxygen atmosphere, 1300°CX 1
2) #Thermal shock resistance refers to the bending strength of samples that were rapidly heated to each temperature for 2 minutes in an electric furnace and then rapidly cooled in water. The processing temperature is expressed as ΔT.

Note 3)': Indicates the value measured using the 4-terminal resistance method.

Claims (1)

[Claims] 1. ZrB_2 as the main component, 1 to 15% SiC, 5 to 20% B_4C, and 3 to 40% ALN in weight%
A conductive ZrB_2 composite sintered body characterized by containing the following. 2. The sintered body according to claim 1, wherein the total amount of SiC, B_4C, and ALN is 15 to 50%.