JPS5864271A - Silicon nitride 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] Jin's invention is a non-oxide material with high high temperature strength and high density.
That is, it is a nitride ceramic sintered body KIII.

Recently, ceramic materials, particularly ceramics, have been actively used as heat-resistant materials, and among them, covalent compounds that are heat-resistant substances that are stable at high temperatures, especially silicon nitride (SilN4), silicon carbide* ( SIC) is known to be an excellent material.

Ceramics are generally used by molding and sintering raw ceramic powder, such as Si, N, etc.

In the case of SjC, etc., since it is a sinterable material different from general oxide ceramics, it has a single composition such as Si,
Even if only N4 powder is sintered, a dense sintered body can be obtained.Fi
Have difficulty.

In the case of this *j6s imported N4 @ end, K FiMgO,A
jlO@.

Sintering is performed by adding oxide powder such as YIO@*Ce01#BeO as a sintering aid.

The commonly used method of press forming using powder containing a sintering aid and then applying TLK and sintering in vacuum or normal pressure has low sintering costs and can be used on an industrial scale.

In the case of Si and N, pores remain as they are even after sintering, so a sintered body with a relative density of about 97% can be obtained by this method.

On the other hand, according to the hot press method in which sintering is performed under pressure at high temperature, a denser sintered body can be obtained.

Furthermore, the mixing ratio of the sintering aid may be reduced, or the powder may be sintered in a high-pressure gas atmosphere without the addition of a sintering aid, or the powder may be pulverized by instantaneously applying high pressure using explosive molding, etc., and then sintered. FFL methods have been attempted, such as sintering, but this method also has the drawbacks of high sintering costs and a reduction in high-temperature strength, and has not been successful as an industrial method.

By the way, the conventional method for producing 5J-4 powder, which is the starting material for non-oxide Cefmix sintered bodies, is to heat a mixture of silica powder and diagonal powder to 180% in a N3 gas stream.
Heating at 0-1700℃, nitride Vt800-1900
There is a method of obtaining it by performing a gas phase reaction in the humidity range of ℃.

The Si@N4 powder produced by any of these methods can also be used as a manufacturing material for the sintered compact.

The S-N sintered body produced in this way is being considered for application to automobile engines and turbine engines as a ceramic with high thermal shock resistance and toughness, and is also being used in various treatments. Applications to tools are already underway.

Another feature of the 516N4 sintered body is that it has poor reactivity. For this reason, there is a drawback that it is extremely difficult to join the 5ilN4 sintered body to different types of ceramics or metals.

The inventors of the present invention have studied to solve the above-mentioned drawbacks of the Sj@N4 sintered body, and as a result, they have arrived at this development.

That is, this invention provides At! 0. and yto
, powdered sintering aid in an amount of 1 to 20% by weight, V, W, Mo.

At least one kind of metal silicide powder such as Ti, Y, etc.
- Mixed powder with 5 to 40% by weight added to N, gas or #:
tN! It has been discovered that by sintering in a non-oxidizing atmosphere containing gas, it is possible to obtain a silicon nitride unsintered body that can be bonded to metals in other ceramics.

It is known that in order to obtain a Si@N4 sintered body using general K St and N4, sintering is performed at 1700°C or higher in N gas at 1 atm. 60.
.

It is also known to add oxides such as MgO and FeO as sintering aids. However, with such sintering, #'1
Since SisN4 decomposes, AmBN is used to prevent this.
It has also been possible to sinter the powder by backing a mixture of Si, N, and powder.

However, although the 5isN4 sintered body thus obtained has properties of high strength and high density, it lacks bondability.

Si, N, powder, AZ=O, Y, O, powder sintering aid, KV, W, Mo, T1. Add a metal silicide such as Y, and sprinkle this mixed powder with N2 and N! It is sintered in a non-oxidizing atmosphere containing gas.

According to such sintering, the metal silicide is decomposed in an atmosphere containing sNR gas or FiN2 gas, and the surface of the sintered body - K t
Gold I11 layers such as Me, W, etc. appear, and these metal layers can be bonded to Si, Si, etc. using a method similar to the single gold bonding method to form a gold j4 solid solution.
N, the bonding of the sintered body with other ceramics or metals is
It becomes a leopard.

The sintered body obtained by this invention is cut into a desired shape from a material such as a plate or rod, and only the parts to be joined are placed in an atmosphere containing high humidity N8 gas. By processing with , it is possible to easily perform a new metallizing process in the direction of cut V#.

As mentioned above, the amount of metal silicide useful for improving the bondability of the sintered body is preferably F15 to 4o1tm*. The reason for this depends on the required bonding strength, but if less than 6% by weight, the metal silicide decomposes and the amount of gold adhering to the surface layer of the sintered body is insufficient, and if more than 40% by weight is used, ,
This is because the characteristics of the 5ilN4 sintered body are lost.

There are many compounds with different atomic ratios as whole-line silicides, but among them, Mo6S-M
o@Si * w, sil, WSiz, CoSi,
Co51ne NiSi.

etc.'' are particularly effective. The reason for this is that all of these wires have good wettability with the metal layer as a metal layer deposited on the sintered body by sintering.

In addition, the amount of At, O, and Y2O5 powders used as sintering aids is preferably 11 to 20% by weight.

This is because if it is less than 11 ifi51, sufficient sintered density cannot be obtained during sintering, and if it is more than 20 weight ilt%, the grain boundary layer of Si3N2 becomes a glass layer and the high temperature strength decreases.

And this At, 0. h and o for the usage ratio of Y2O3 and Y2O3.
Aggression: Y, 0. A ratio of 8:1 to 1:8 is suitable; other values are not preferred because the heat resistance of the sintered body obtained with Fi will be low.

In addition, the sintering conditions in this invention are 1650 to 1
A suitable time is 850°C for 0.5 to 6 hours.

Thus, Si, N with improved bonding properties of the present invention
4 Sintered compact h% Because the metal in the surface III layer is deeply leaked into the sintered compact, it is possible to obtain a high-strength bonding layer with slight vibration compared to vacuum A-plating or normal metallizing method. It can be done.

The atmosphere during sintering in this process 11 was N,
In addition to gases that serve as nitrogen supply sources such as , NH, and CO, H! There is no problem even if it is a mixed gas with No. 41 gas.

Next, this will be explained in detail using Example #11.

Example 5 Made by tarckit, ) I-1 grade Si@N4
A sintering aid and Jinpeng silicide powder were added to the powder in the amounts shown in Table 1, and the mixture was stirred in a ball mill for 10 hours.

After drying the resulting slurry, add stearin soap as an organic binder to it, and add 2 test pieces of 10 x 7 x 40 cm to it.
It was created by stamping with TLCD.

This was placed in a known backing material and sintered at 1760° C. for 1 hour in an N2 gas atmosphere.

When the properties of the nine sintered bodies obtained were investigated, the results shown in Table 1 were obtained.

In addition, for the joint test, a Si 8N4 sintered body of the same size obtained in this invention was attached to the tip of a square bar-shaped SK material 5 × 5- with a silver lock [, the SK material side of this test piece was held]. Then, the sintered body was coated with Illustrator to determine whether or not the bondability was IL-induced at room temperature.

As a result, it was found that the #'i silver sintered body with good bonding properties was broken internally, whereas the FiSi and N4 sintered bodies with poor bonding properties were peeled off on the surface.

This is presumed to be due to the difference in bonding strength between the surface of the N4 sintered body and the metal layer.

Table 1; ― ■ Glue The above examples were all about pressureless sintering, but
The present invention is not limited to pressureless sintering, and the same effect can be obtained even in the case of a sintered body obtained by hot pressing.

Claims (3)

[Claims] (1) (a) kl, Ol and Y, 0. 1~ powder of
20% by weight (b) V, W, Me, Ti,
5 to 4 at least one kind of metal silicide powder such as Y
0 heavy aS (Q) A silicon nitride burner characterized in that the remainder is sintered using a mixture of silicon nitride powder. (2) The silicon nitride powder has a particle size of 0.1 to 5μ and a total amount of other metal impurities in the powder is 1%. body. (3) Mixed powder woN! A silicon nitride sintering body as claimed in claim 1, characterized in that it is sintered in a gas atmosphere. /4) A silicon nitride sintering body, characterized in that the gold powder is sintered in an atmosphere containing the gas.