JPS62108776A - Manufacture of tough sialon - 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 method for manufacturing sialon.

In particular, the present invention relates to a method for producing strong sialon with excellent mechanical properties using 5i3Nn raw material powder with a low gelatinization rate as a starting material.

[Conventional technology]

SiAQON is S isN s +
Although it is a ceramic solid solution of A Q zOl and AQN, conventional sialon is mainly β-type sialon, and is manufactured using α-type Si3N4 powder with a gelatinization rate of 90% or more as a starting material. In this case, transformation from α-type to β-type takes place, and this becomes the driving force for sintering, resulting in a tough β-sialon. Therefore, in the production of β-type sialon, α-type 5ii is used as a starting material as described above.
Requires N4 powder.

[Problem that the invention seeks to solve]

However, the α-type 5iiNn powder described above has the drawback that it is very difficult to manufacture. That is, α type S
The mainstream production of i3N4 is to synthesize it by a direct nitriding method in which Si is directly reacted with N2 gas, but the above reaction is an exothermic reaction, reaching temperatures of 2,000-odd degrees and leaving it as it is. As the reaction progresses, the high-temperature β-type 5
i3Nn is formed. Therefore, it is necessary to control the synthesis reaction temperature with high precision, and in order to make the reaction proceed slowly, a reaction time of at least 100 hours is required. Therefore, α-type 5i3Nn raw material powder is very expensive.

Furthermore, the sialon manufactured by this method also becomes expensive, which is a major factor hindering its practical use.

It is an object of the present invention to provide a method for manufacturing 2-strong sialon at low cost by solving the problems existing in the prior art as described above.

(c) Means for Solving Problems] To achieve the above object, the present invention employs the following technical means. In other words, the alpha conversion rate is 80
% or less Si3N4 powder is used as a starting material, a metal oxide binder is added and mixed, molded and sintered, and 2
This is a method for producing strong sialon, which is α+β composite sialon or α single-phase sialon containing 0% or more α-type sialon.

β-type Si3N as a starting material is converted from β-type to α during sintering.
By transforming into a mold, a sintering driving force is obtained, and by this, the produced sialon is intended to obtain toughness represented by hardness, fracture toughness value, bending strength, etc. If the gelatinization rate exceeds 80%, there will be a large amount of α-type powder, resulting in an insufficient amount of α-sialon produced through the β-α transformation, resulting in a decrease in fracture toughness and bending strength.

Therefore, the gelatinization rate was limited to 80% or less.

Next, in α-type Sialon, a binder such as Y z O's is partially diffused into the lattice of Sialon during high-temperature sintering, and the amount of binder is reduced, thereby improving hardness, bending strength, etc. For this reason, α-type sialon is superior in toughness compared to β-type sialon in which sialon particles are bound with a binder. If the α-sialon content in the sintered body is less than 20%, it is disadvantageous because the fracture toughness value and bending strength are significantly reduced. Therefore, the content of α-sialon was limited to 20% or more.

〔Example〕

S I with particle size 1 um: lN4, A Q N and Y
zO3 was mixed in alcohol for 50 hours in a ball mill, dried in vacuum, and then 1% by weight of wax was added and mixed, followed by press molding. This molded body was sintered at 1800° C. for 3 hours in nitrogen gas at 1 atm, and the results are shown in the table. In the table, No. and those marked with a circle in the column are manufactured by the manufacturing method of the present invention.

Others are comparative examples.

Margin below.

As is clear from the table, Nos. 1 to 7 are all made of raw material Si.
The α type abundance rate in 3N4 is 50%, and in the past, it was a so-called low-grade raw material that was not suitable for producing strong sialon. Nos. 1 to 3 show low values for both fracture toughness and bending strength. This is because the ratio of α-type sialon in the sintered body is small. In other words, this is due to the fact that the sintering driving force for β-α is small. On the other hand, samples Nos. 4 to 7 of the present invention all exhibit high fracture toughness and bending strength. This is due to the high α-sialon ratio in the sintered body.

Next, Nos. 8 to 13 have an α type abundance rate of 95% in the raw material 5i3Na, belong to conventionally used high-grade materials, and have high bending strength and fracture toughness values.

Nos. 14 to 18 have the same raw material composition.

These are the results when the α-type abundance ratio in the raw material 5i3N4 was varied, and Nos. 9 and 14 to 17 of the present invention have high bending strength and fracture toughness values. On the other hand, N
No. 18 shows low values for 1 bending strength and fracture toughness even though the α-sialon content in the sintered body is 100%. This means that the α type in the raw material 5iffr'J4 is 8
It is presumed that this is due to the fact that the amount of β-type is insufficient, accounting for 5%, and the driving force for sintering β-α is small.

In this embodiment, an example was described in which Y2O3 was used as the binder, but it goes without saying that other inexpensive binders such as Cab and MgO may be used to provide the same effect.

〔Effect of the invention〕

Since the method for manufacturing strong sialon of the present invention has the structure and operation as described above, it does not require the conventional expensive α
Type 5iiNa raw material powder is not required.

We can offer Sialon at a relatively low price.

This has the effect of greatly promoting practical application.

Claims (1)

[Claims] Using Si_3N_4 powder with a gelatinization rate of 80% or less as a starting material, adding and mixing a metal oxide binder, molding and sintering to obtain α+β composite sialon or α single-phase sialon containing 20% or more α-type sialon. A method for producing tough sialon characterized by: