JPS61163169A - Manufacture of 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 (Industrial Field of Application) The present invention relates to a method for manufacturing a sintered silicon nitride (SizN4) body.

(Prior art) The conventional S='sNa sintered body uses Al20x as a sintering aid.
, Y20wl, MgO,Mg0-AI2zO
A method of adding Nosvinel and sintering has been used.

(Problems to be Solved by the Invention) However, in order to increase the high temperature strength (1000 to 1300°C), it is necessary to make the particle sizes of Si, N, and raw materials as fine as possible.

On the other hand, when the raw material particle size becomes 0.1 μ or less, sintering aids such as Alt Ox, Yz Ox, MgO, MgO・A
The grain size of lzO3 spinel must also be reduced to 0.1 μm or less, but these materials currently do not exist. Further, even if these materials were made, there is a problem in that it is extremely difficult to uniformly disperse the Si3N4 raw material and the sintering aid, and as a result, the high temperature strength is high (not possible).

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides at least each organic compound of yttrium and aluminum with Si x
A method is adopted in which N- is wet mixed, oxidized, and then sintered.

(Function) During the process of the present invention, organic compounds are uniformly adhered and dispersed on the surfaces of Si and N. When this is oxidized, the organic compounds become A l z 03 and YzOl, respectively, and these oxides are uniformly dispersed on the surfaces of Si, N, and raw materials.

(Effect of the invention) Therefore, according to the present invention, the sintering aid is uniformly applied to Si3N,
Since it can be dispersed on the surface of the metal and is very fine, it has high strength at high temperatures and has the effect of reducing the amount of sintering aids.

(Example) The manufacturing method of the present invention will be explained in detail for each step.

+1) Method for making Si 3Na powder ■Metal Si powder 0.8-3μ (particle size) at 1200-1400℃, Nz
Made by nitriding in a gas stream (α-like St, N4
(crystal) is ground into a powder of 0.7 to 0.8μ.

A representative example of this is the LC12 manufactured by Starck in West Germany.
There is a Nippon Denko type N-2.

■5t(N
Hri 4 (silicon imide) at 1200-1400℃
α-form 5t3N obtained by treatment in two air streams, crystalline (
The particle size is 0.2 to 0.7μ). Typical examples include Ube Industries type 0.25-0.4μ, Toyo Soda 0.
．． Some have a diameter of 4 to 0.7μ.

■SiHg (or 5iCj?<) and N2 (or NH
a”) in a plasma stream to form amorphous Si.
, N, ultrafine powder with a particle size of 0.1 μ or less
Nitriding treatment is performed at 00°C in a N2 gas stream to obtain ultrafine powder with a particle size of 0.1 μm or less.

(2) Method for creating organic compounds of organic ythtrium, organic aluminum, and organic magnesium C, IH211,1
Yttrium is a C00H compound.

By reacting aluminum and magnesium, for example, Y (
Cs H7Of ) *-, A l (OCOCtHs
)3 AI! (OCOCH*)33Mg (○C
OC2H5')! , and MgAl1. (i-○CxH
t) Use s.

(3) Si3N4 and organic yttrium, aluminum,
Si:+N:+ powder 10 mixed with magnesium in a ball mill made of Si, N,
0 parts by weight and Yz O3, Affi20x.

1 to 5 parts by weight of the above organic compound in terms of MgO is added. In addition, the following ■, ■, ■.

In the reaction of ■ and ■, Y2O3,A /l z 03,
Mg O, Mg A j! Since z O4 is created respectively, the resulting Yz Ot and At1z Oar
, an amount of organic compound corresponding to 1 to 5 parts by weight of MgO is added.

2Y (C5H? O□)3+330□→YtOs+3
0CO□ +21H20・・・・・・■2Al (O
COCz Hs ):l +210z →All
03 ” 18 Cot + 15 H20...”
0Mg (OCOCz Hs )2 +'
yo□ →MgO+6COz +5Ht O...
・・・・・・・・・・・・■2Affi (OCOC
z Hs )s +Mg (QCOCz H
s)t + 280□ →MgA1z 03
"24COz + 20Hz O...
・・・・・・・・・0 Mg+2Affi (i-QC,H,),+'l
iC3H70H→ MgAlz (i 0C3H? )s +)
(.

(Japan Ceramics Association Journal 92 (11) 1984.P2O3)
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・■MgAl
z (i −0C3H? )s +360□ −
Mg”2 0a +24CO2+ 28Hz O・
・・・・・・・・・・・・1...■ Then, add ethyl alcohol to the above ball mill for 10 minutes.
Add 0 to 500 parts by weight and stir and mix for 3 to 24 hours.

Here, since ethyl alcohol and the organic compound uniformly dissolve in each other, they can be mixed uniformly.

(4) Dry the mixture at 70 to 80°C for 1 to 2 hours while stirring. In addition, vacuum deaeration drying may be performed for 1 to 2 hours while stirring. In this way, organic yttrium, organic aluminum, and organic magnesium adhere almost uniformly to the surface of the 3 i 3 Nm powder. At this time, if the S 1 z N4 powder is dried without stirring, a large amount of organic compounds will be deposited on local parts of the surface of the S 1 z N4 powder, and a small amount of organic compounds will be deposited on other parts. In other words, ethyl ``1 alcohol vaporizes and scatters during drying, and it becomes the Si3N surface of the mixture.
4. Since the powder gradually evaporates and scatters, the S on the surface gradually disappears.
As organic compounds are deposited on the i3N4 particles, the S j x N on the surface compared to the Si3N inside the mixture
4 The concentration of organic compounds on the powder becomes high, making it impossible to obtain a uniform adhesion state.

(5) The dried product is fired at 600° C. for 2 to 6 hours in the air.

In this way, the organic compounds attached to the surface of Si3N are oxidized by the reaction based on the above-mentioned formula 0.0.0.0, forming ultrafine particles (ultrafine particles with a particle size of 0.1μ or less), and their distribution is uniform. Become something.

(6) Fill this into a mold of the desired shape, and
Press at a pressure of 4000 kg/cm. This press can be a mold press, a rubber press, etc. In the case of a mold press, which can also be used as a mold press and a rubber press. is 100-800 kg
/ cmt% 600-4000 for rubber bracelet
kg/cm" is used.

(7) This was heated to 1650-18 in N2° and argon stream.
Bake at 00°C for 1 to 4 hours. For example, commercial product Starta L
C-12 particle size 0.5 to 0.7 μ, St with a degree of gelatinization of 90% or more, N, powder weight fa y zOy, A Ilz
The density of 3 parts by weight including 0+ is 3.16 g/cc at 1650°C, 4 hours - 3.20 at 1700°C, 2 hours,
1750℃, 3.20g/cc for 1 to 2 hours, 1800
3.19 g/cc can be obtained in 1 hour at ℃.

When a 3-point bending test was performed on the 5izN4 sintered body created through the above process, it was found that the weight was 85 to 100 kg/mm" at room temperature, and 120
45-55 kg/mm" was obtained at 0°C.

(Comparison between the conventional method and the method of the present invention) Conventional auxiliary addition method, namely YZ 03 , A 1 t
03.

M g O, M g O・A Ilz O:I simply S
Compared to the method of mixing with i3N4 powder, the present invention provides Si:
The dispersion of +Na powder and these auxiliary agents is extremely good, and as a result, Y20:+, Al1zOz, MgO, MgO
' Only a small amount of Alzox is required. For example, in the conventional method, a total of 10 parts by weight of auxiliary agents is required, but only 1 to 6 parts by weight can be used. Furthermore, the bending strength at high temperatures is significantly improved. This is shown in FIG.

The specifications of the conventional and present invention shown in FIG. 1 will be explained.

(Conventional) Using LC-12 manufactured by Starck with a SilN4 powder particle size of 0.5 to 0.7μ, and Y with a particle size of 0.2 to 0.3μ, respectively.
2O, and Alto at a ratio of 1:1, and the above 5
4X3X by changing the amount added to isN4 powder by the usual method
It was fired to a size of 50. Three-point bending strength was measured based on JIs.

(Invention: 1) Made by the above method, the auxiliary agents are Y, 03 and Al□
0. A combination of This Y2O3.

The ratio of Al1zoz is 1:1 by weight. The sintered body had dimensions of 4×3×50 (1), and its three-point bending strength was measured based on JIS.

(Present invention: 2) Organic yttrium, organic aluminum, and organic magnesium are mixed so that the ratio of organic yttrium, organic aluminum, and organic magnesium is 1:1 (wt%) in terms of Yz Ox, M g A l z 04. A solution layer is created by mixing the following in a predetermined ratio. In this solution 5 i 3 N
LC-12 manufactured by Starck was added to the powder a, and mixed in a ball mill for 6 to 12 hours. After drying this, 800-1
Bake at 000°C for 1 to 2 hours. Through this process, organic yttrium is converted into YzOx, organic aluminum and organic magnesium Mg0-AJ z 01 (M g A 1
2 z O4) spinel and adheres to the surface of Si, +N, and powder in the form of ultrafine powder.

This was sintered to obtain a 4X3X50 (j2) sintered body. The three-point bending strength of this was measured based on JTS.

(Other Examples) Ultrafine powder α degree of gelatinization is 90% or more, purity is 99% or more (0.03
~0.09μ) Si3N, fine powder 0.2-0.3μα
FIG. 2 shows the results when using 5t3N4 with a chemical degree of 99% UP (manufactured by Ube Industries). When ultrafine powder is used, good results can be obtained even with a smaller amount added. This is because ultrafine powder provides higher strength because it has the effect of increasing density during sintering. For example, the density of ultrafine powder is 3
．． 2g/cc, the density of fine powder is 3.19g/c
It was c.

In addition, in FIG. 2, the auxiliary agent is yz　o3. Az.

0, (the starting material is in the form of an organic compound), and the mixing ratio is l:1 (weight ratio) in the form of an oxide.

[Brief explanation of drawings]

FIGS. 1 and 2 are characteristic diagrams for explaining the present invention in detail.

Claims (1)

[Claims] A silicon nitride sintered body characterized by wet-mixing at least organic compounds of yttrium and aluminum with silicon nitride powder, treating the mixture at a temperature at which each of the organic compounds oxidizes to yttria and alumina, and then sintering. manufacturing method.