JPS596836B2 - Manufacturing method of ceramic powder material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing high strength ceramic powder materials.

For example, silicon nitride sintered bodies have attracted attention as sintered bodies with excellent high-temperature strength, but the raw material ceramic powder used therein has not been fully elucidated.

The present inventors disclosed in Japanese Patent Application No. 52-1949 that the use of deoxidized ceramic powder material produces good results in order to reduce the glassy portion in the sintered body. revealed.

The present invention discloses a method for more effectively and efficiently deoxidizing the ceramic powder described above.

That is, one of the objects of the present invention is to obtain a method for producing a ceramic powder family that makes it possible to reduce the glassiness in the sintered body.

Another object of the present invention is to provide a method for producing a vine ceramic powder material that further improves the high-temperature strength of a sintered body.

Yet another object of the present invention is to provide a method for efficiently producing deoxidized ceramic powder materials.

Other objects of the invention will be understood from the following description.

The manufacturing method of the present invention consists in heating a ceramic formed body or/and a ceramic formed body having a porosity of 10% or more together with the ceramic powder to be treated, in order to deoxidize the ceramic powder raw material.

For example, by heat-treating the raw material of silicon nitride powder together with a formed body of aluminum nitride, boron nitride, titanium nitride, silicon nitride, aluminum oxide, etc. or (and) a sintered body with a porosity of 10% or more, The silicon nitride powder raw material is effectively deoxidized.

Aluminum nitride is most effective as the above-mentioned formed body or sintered body.

When the above-mentioned green bodies and sintered bodies are used, gaseous substances containing oxygen released from the ceramic powder during heat treatment are absorbed and fixed in these green bodies and sintered bodies, or via the green bodies and sintered bodies. Is it discharged outside the system? It is believed that the deoxidizing effect is effectively achieved because this reduces the partial pressure of the oxygen-containing gas within the ceramic powder system and helps release the oxygen-containing gas from the ceramic.

That is, for example, when silicon nitride powder is heat-treated together with an aluminum nitride compact, SiO in the silicon nitride powder reacts with AlN to form an AASi10-N compound, and as a result, Si02 is absorbed and fixed in AlN. be done.

Furthermore, when the silicon nitride powder is heat-treated together with the silicon nitride sintered body, Si02 travels through a small space between the powder and the sintered body and scatters out of the system.

When a green body is used, the activity of the powder particles constituting the green body is high, which is advantageous in that the effect of absorbing and fixing the oxygen-containing gas generated from the ceramic powder is large.

When using a sintered body with a porosity of IO% or more, the activity of the particles that make up the sintered body is reduced to a certain extent, so the reaction at the contact surface with the ceramic powder that is also heat-treated is minimized. This is advantageous in that the oxygen-containing gas released from the ceramic powder is absorbed while being kept to a minimum.

The reason why the porosity of the sintered body is set to 10% or more is because if it is less than this, the sintered body particles will have fewer pores, making it difficult for the oxygen-containing gas released from the ceramic to penetrate into the sintered body, reducing the effectiveness. It is.

For the same reason, the porosity of the formed body is preferably 10% or more.

The silicon nitride raw material to be heat-treated may contain impurities such as iron and calcium which are normally contained therein, or magnesium oxide, yttrium oxide, aluminum oxide, etc. which are added to promote sintering.

The heat treatment is preferably carried out in a container that is non-reactive with the powder to be treated, such as aluminum nitride, boron nitride, silicon carbide, or the like.

Experiments have shown that aluminum nitride is most preferred.

The heat treatment atmosphere may be any non-oxidizing atmosphere, such as an inert gas atmosphere or a nitrogen atmosphere.

The heating temperature is 1300 to 1900°C, preferably 1
400-1850℃, more preferably 1500-18
It is 00℃.

For example, the following ceramic powder materials can be obtained by the manufacturing method of the present invention.

■ The activation analysis value shows that the amount of oxygen corresponding to unavoidable impurities is 2.
．． Ceramic powder material mainly composed of silicon nitride with a content of 0% by weight or less.

■ Aluminum is in the range of 0.05 to 2.5% by weight, yttrium is in the range of 0.4 to 8.0% by weight, and the activation analysis value shows that the total oxygen content (Wo) is in the aluminum content (wt%).
A ceramic powder material mainly composed of silicon nitride, which is in the range shown by the following relational expression between WAl) and the amount of yttrium in weight % (wy).

(2) The ceramic powder material described in (2) above, in which part or all of the yttrium in the powder exists as a compound of silicon nitride and yttrium oxide.

In order to make a good ceramic powder material for silicon nitride powder containing alumina and yttria as additives, it is necessary to add 0.1 to 5% by weight of alumina and 0.5 to 10% by weight of yttria.
Silicon nitride powder added with 1400 to 1900 wt%
It may be heated to ℃.

This heating temperature is preferably 1450 to 1850°C, more preferably 1500 to 1800°C.

When using a silicon nitride raw material to which alumina or yttria is added, it is more preferable that part or all of the yttrium in the ceramic powder material powder obtained by heat treatment exists as a compound of silicon nitride and yttrium oxide.

The presence of this compound can be confirmed by X-ray diffraction.

To generate this compound, the heat treatment temperature is 1600.
It is best to keep the temperature above ℃.

Example 1 0 was investigated by activation analysis, N by gas analysis, and the others by normal wet analysis.The results were as follows: Si 58.6% by weight, N 36.1% by weight, 04.3% by weight, FeO. 25% by weight, CaO. 2
When 1% by weight of silicon nitride powder was heated at 1,700°C for 30 minutes in an aluminum nitride container with aluminum nitride formed bodies mixed therein, Si was 59.2% by weight and N was 36% by weight.
9% by weight, 01.8% by weight, Fe0.28% by weight, Ca
A powder of 0.25% by weight was obtained.

It took one hour of heating time to obtain the same analytical values as above without mixing aluminum nitride formed bodies.

2% by weight of alumina and 5% by weight of yttria were added to powders without heat treatment and powders subjected to heat treatment to reduce the amount of oxygen, and after molding, they were heated at 1800°C for 2 hours at 500kg/crA. It was sintered while applying pressure.

As a result, the anti-destructive strength at 1200°C was 53 kg/mA using silicon nitride powder that was not subjected to heat treatment.

On the other hand, the anti-destructive strength at 1200℃ of silicon nitride that has been heat treated to reduce the amount of oxygen is 75kg/ma.
Met.

The sample size used for the anti-deposition test was 3X 3X 3 5 (T
t7It), and the test conditions were a crosshead speed of 0.5 y/sec and a span of 20 m/m.

This result shows that deoxidation is more effective when the produced form is used.

The same result was obtained even when a sintered body having a porosity of IO% or more was used.

Example 2 A silicon nitride raw material powder containing 25% by weight of alumina and 4.8% by weight of yttria was prepared and heat-treated at 1750° C. for 2 hours in an aluminum nitride container.

When the obtained powder was analyzed in the same manner as in Example 1, Si5
5.7% by weight, All. 3% by weight, Y3.8% by weight, F
eO. 31% by weight, CaO. 26% by weight, N32.6% by weight, and 02.6% by weight.

Further, X-ray diffraction revealed that the compound (S13N4・Y20
3) was produced, and it was found that 90% of the amount of yttrium in the entire powder was present as this oxynitride compound.

In order to obtain a powder material similar to this powder material, when a formed form of aluminum nitride is mixed and heat treated, 70%
Similar results were obtained within minutes.

The same result was obtained when a sintered body having a porosity of 10% or more was used.

After molding this powder, it was heated to 1,800℃ for 2 hours, and then
Sintering was performed while applying pressure of /crA.

When the obtained sintered body was subjected to a bending test under the same conditions as in Example 1, a strength of 92 kg/Wl7j was obtained at 1200°C.

Example 3 Advanced Materials Engineering (UK)
Silicon nitride powder (grade CP-85) manufactured by Co., Ltd. was prepared.

This powder contains 87% α-type silicon nitride and has a particle size of 1.8μ.
Met.

This starting material contained 57.8% by weight of Si, 35.5% by weight of N, and AlO. 23% by weight, FeO. 35% by weight, CaO
．． 1.1% by weight, 03.5% by weight.

5% by weight of IJA was added to this raw material and mixed by pulverization in an alumina pot using an alumina ball.

The obtained powder had a particle size of 1.1μ and contained 56.5% by weight of Si and N.
34.7% by weight, A. l.

31% by weight, Fe0.32% by weight, CaO. ]. They were O weight %, Y 3.69 weight %, and 05.31 weight %.

This powder was placed in an aluminum nitride container with a porosity of 8% and 1
Heat treatment was performed at 1650° C. for 2 hours together with the formed bodies and sintered bodies of 0%, 30%, 50%, and 70% aluminum nitride.

Oxygen content of the obtained powder and sintering of this powder (1800℃
, 400kg/cyn. The flexural strength of the sintered body obtained after 2 hours) is shown in the table below.

When the porosity of aluminum nitride exceeds 70%, handling becomes difficult.

If the porosity is less than 10%, the effect will be small.

When heated for 30 minutes, the amount of oxygen was 4.4% in the case using aluminum nitride with a porosity of 8%, while it was 4.0% in the case of the case with a porosity of 10%.

In addition to aluminum nitride, boron nitride, titanium nitride, silicon nitride, or aluminum oxide may be used as the formed body or sintered body to be mixed with the treated powder.

Note that the formed body or sintered body to be mixed with the treated powder is not limited to a single body.

For example, materials to which yttria, alumina, silica, etc. are added can also be used.

However, it is preferable to limit the amount of these additives to 20% or less.

This is because if more additives are added, the ceramic powder will undergo sintering shrinkage during heat treatment, which will prevent the diffusion of oxygen-containing gases and reduce the deoxidizing effect.

Claims (1)

[Scope of Claims] 1. Ceramic powder containing silicon nitride as a main component, or a ceramic product containing aluminum nitride as a main component or (and)
A method for producing a ceramic powder material, which comprises heat-treating the material together with a ceramic sintered body having a porosity of 10% or more. 2. The method for producing a ceramic powder material according to item 1, wherein the silicon nitride-based ceramic powder contains 0.1 to 5% by weight of alumina and 0.5 to 10% by weight of yttria. 3. The method for producing a ceramic powder material according to claim 1 or 2, wherein the heat treatment is performed at 1400 to 1900°C.