JPS5834428B2 - Method for manufacturing silicon nitride ceramics - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing silicon nitride ceramics.

Since it is difficult to sinter silicon nitride alone, various additives have been added to it for sintering.

For example, Mgo, Al2O3, Y2O3, etc.

Among these additives, it is known that a sintered body to which Y2O3 and A12o3 are added in combination is superior to the case where other additives are added in terms of high temperature strength, thermal shock resistance, etc.

However, simply adding Y2O3 and Al2O3 may be unsatisfactory from an industrial standpoint.

According to the inventor's research, when trying to obtain larger products, meticulous manufacturing techniques are required to improve the homogeneity of the entire product, such as density distribution, and even rougher manufacturing techniques can achieve high quality. Materials from which products can be obtained are desired.

As a result of intensive research, the inventors of the present invention found that the above requirements can be met by adding AIN to SiO2 together with a rare earth element oxide and Al2O3 within a certain range.

Therefore, in the technology 6 East weight ratio presented by this application, 0.1 to 1 part of rare earth element oxide is added to 100 parts of silicon nitride.
0 parts, aluminum oxide 0.1-10 parts, silicon oxide 0
．． 1 to 10 parts of aluminum nitride, and 0.1 to 4 parts of aluminum nitride, with the amount of aluminum nitride being 1/1/1 of the amount of silicon oxide.
The present invention provides a method for producing silicon nitride ceramics, which comprises molding and sintering a mixed powder having a ratio of 10-10/1.

Addition of aluminum nitride in a small amount of about 4 parts is beneficial in easing the sintering conditions, and specifically, it is possible to produce high-strength, homogeneous products even with relatively low sintering temperatures and short sintering times. You can get it.

On the other hand, if the amount of aluminum nitride is too large, the amount of solid solution of aluminum nitride relative to silicon nitride will be large, and as a result, the product will be different from a high-performance ceramic made by adding a rare earth element and aluminum oxide to silicon nitride.

Aluminum nitride also has a relationship with the amount of silicon oxide.

Silicon oxide may be mixed in when it is attached to the surface of silicon nitride powder, but it also works as a sintering aid.

However, if the silicon oxide content is too large, although sintering becomes easy, the resulting sintered body will contain a large amount of glass, which will adversely affect properties such as strength.

This negative effect is reduced by the addition of aluminum nitride.

That is, it is necessary to add aluminum nitride in a range of 1/10 to 10/1 to silicon oxide in order to obtain the above effect.

Note that in addition to the amount of silicon oxide that adheres to silicon nitride, it is also permissible to add any amount of silicon oxide.

In addition, if the amount of rare earth element oxides, aluminum oxide, and silicon oxide is too small, the original requirements such as high density and high strength of the sintered body will not be met, while if too large, the high temperature strength and thermal shock resistance will not be satisfied. decreases.

Therefore, the amount of rare earth element oxide is 0.1 to 10 parts, preferably 0.5 to 8 parts, and most preferably 1 to 5 parts.

Aluminum oxide is 0.1 to 10 parts, preferably 0.5 parts
-5 parts, most preferably 0.5-3 parts.

The silicon oxide is present in an amount of 0.1 to 10 parts, preferably 0.1 to 5 parts, and most preferably 0.5 to 2 parts.

Aluminum nitride is 0.1 to 4 parts, preferably 0.1 to 4 parts.
2 parts, most preferably 0.5-2 parts.

Amount of aluminum nitride/silicon oxide is 1/10 to 10/
1, preferably 172 to 4/1, most preferably 1/1
~2/1.

In the present invention, rare earth elements include Y and La.

Ce, Pr, Nd, Pm, Sm, Eu, Gd.

Tb, Dy*Ho, Er, Tm, Yb, and Lu.

A suitable sintering temperature according to the present invention is 1400°C to 1900°C.

If the temperature is too low, densification will not proceed sufficiently, and if it is too high, silicon nitride will decompose rapidly.

The preferred sintering temperature is 1300-1850°C.

Moreover, the sintering time is suitably 0.5 to 5 hours.

This is because if the length is too short, densification will not proceed sufficiently, and if it is too long, oversintering will occur.

Sintering techniques include various known methods, namely normal sintering,
Hot press, hot isostatic pressure method, etc. can be adopted.

Ordinary sintering has the advantage that complex-shaped objects can be easily obtained.

Hot pressing has the advantage that it can be densified in a short time.

The hot isostatic pressure method has the advantage that a dense sintered body can be obtained at a relatively low temperature.

As the molding technique, various known methods such as slip casting, mold pressing, injection molding, extrusion molding, etc. can be employed.

Experimental Examples Silicon nitride powder with an average particle size of 1.5μ, aluminum nitride powder with an average particle size of 1.3μ, aluminum oxide powder with an average particle size of 1.0μ, silicon oxide powder with an average particle size of 1.0μ, average diameter A mixed powder shown in Table 1 was prepared using ittria powder of i, oμ and cerium oxide powder with an average particle size of 1.0μ, and 10% of paraffin was added as a binder to it.
A plate-shaped body having a thickness of 30 mm, a length of 100 m, and a width of 100 mg was molded under a molding pressure of 5 tolN 7 cm.

This molded body was first heated in a nitrogen flow of 8001/hr.
It was heated and sintered under the conditions shown in the table.

The properties of the obtained sintered body were measured and the results shown in Table 1 were obtained.

The following can be understood from Table 1.

Comparing Sample 1 with Samples 2 to 5, it can be seen that by adding AIN, a product with less uneven density can be obtained.

2 Comparing Samples 2 to 5 with Sample 6, it can be seen that too much AIN causes deterioration in characteristics.

3 Samples 7 and 8 show that changes in characteristics occur due to changes in the amount of SiO2.

4 Sample 9 shows that Ce 02 may be used as the rare earth element oxide.

5 Samples 10 to 11 show that changes in properties occur due to changes in the amount of Al2O3.

6 Samples 12 and 13 show that changes in properties occur due to changes in the amount of rare earth element oxides.

7 Comparison of Sample 14 and Sample 15 shows that the properties of the samples to which AIN was added do not deteriorate significantly due to a decrease in the sintering temperature.

Claims (1)

[Claims] 1. 100 parts by weight of silicon nitride, 0.1 to 10 parts of rare earth element oxide, 0.1 to 10 parts of anohenium oxide, 0.1 to 10 parts of silicon oxide, and nitride. aluminum 0.1
A method for producing silicon nitride ceramics, comprising forming and sintering a mixed powder consisting of 4 parts of aluminum nitride in a range of 1/10 to 10/1 of the amount of aluminum nitride. 2 The amount of aluminum nitride relative to the amount of silicon oxide is 1/2
A method for producing a silicon nitride top six according to claim 1, wherein the ratio is within the range of 4/1 to 4/1.