JPS6385017A - Production of nitrogen-containing glass - Google Patents

Abstract

PURPOSE:To industrially obtain a homogeneous nitrogen-containing glass rick in a nitrogen content, by heat-melting a mixture of an amorphous silicon nitride powder and metal oxide constituting glass under a nitrogen-containing gas atmosphere and rapidly cooling the melt. CONSTITUTION:A mixture of an amorphous silicon nitride powder and at least one kind of metal oxide or metal salt which is thermally decomposed to give said metal oxide is heat-melted under a nitrogen-containing gas atmosphere and then rapidly cooled. An amorphous silicon nitride and metal oxides constituting glass are preferably mixed so that nitrogen content in the produced nitrogen- containing glass is a ratio of 2-20atom%. The metal salt which is changed to the metal oxide by above-mentioned thermal decomposition includes carbonate, basic carbonate, oxalate, hydroxide, etc. Rapid cooling rate after heating is especially preferably 300-2,000 deg.C/min.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing nitrogen-containing glasses.

[Prior art and seven problems]

In recent years, nitrogen-containing glasses in which oxygen in oxide glasses is replaced with nitrogen have been attracting attention as new glasses. Nitrogen-containing glass has higher strength, hardness, and refractive index than oxide glass having the same metal composition, and has excellent heat resistance.

Nitrogen-containing glass is a high-temperature window material with excellent heat resistance.

It is used as a hard glass with excellent wear resistance.

Conventional methods for producing nitrogen-containing glass include (1) a) metal nitride such as silicon nitride or aluminum nitride;
5i02, At2o3 r Na2O+ Y2
O3+ A method of heating and melting a mixture with metal oxides such as MyO and CaO under normal pressure and nitrogen atmosphere.

However, this method causes the scattering of SiO and N2 due to thermal decomposition, so glass with low nitrogen content,
Only glass with bubbles inside could be manufactured.

Therefore, in order to suppress thermal decomposition, b) metal nitrides such as silicon nitride, aluminum nitride, etc.
5i02, At203, Y2O3, MfO
, aao, Nan.

1.5 to 200 Kg/a of a mixture with metal oxides such as
A method of melting in a pressurized nitrogen gas atmosphere (Unexamined Japanese Patent Publication No. 56
-100141).

C) One or more of alumina, silica and germania
20 to 70 moles of silicon nitride solid solution with 5 moles or more, 20 to 70 moles of silica, and 10 to 10 moles of one or more of sodium oxide, potassium oxide, lithium oxide, boron oxide, and phosphorus oxide as the oxide composition in the final product. ~
A method of melting and molding a raw material mixture blended in a range of 30 mol to a total of 100 mol (Japanese Patent Publication No. 53-3
No. 403).

It has been known. However, method (b) requires a pressurized atmosphere furnace and is not suitable for industrial mass production.

In the method (C), a silicon nitride solid solution is first produced.

To use the crushed powder of the sintered body as a raw material for glass.

This method is not satisfactory as an industrial production method in terms of the cost of pulverization and the contamination of impurities during pulverization.

[Object and gist of the invention]

The object of the present invention is to avoid the above-mentioned disadvantages.

An object of the present invention is to provide an industrial method for producing homogeneous nitrogen-containing glass with a high nitrogen content.

The gist of the present invention is to provide one or more types of amorphous silicon nitride powder and metal oxides constituting glass or metal salts that become the metal oxides through thermal decomposition (hereinafter both are collectively referred to as glass-forming compounds). The method consists of heating the mixture at 1400 to 1800°C under a nitrogen-containing gas atmosphere and then rapidly cooling it.

[Detailed description of the invention]

As the amorphous silicon nitride powder, those manufactured by conventionally known methods can be used. For example, a so-called amorphous material is a substance obtained by further heat-treating the reaction product of silicon tetrachloride and ammonia in a liquid or gas phase. powder. It should be noted that, depending on the conditions of the heat treatment, the above-mentioned reaction product may be a powder that shows a slight diffraction phenomenon in X-ray diffraction, and such powder is also included in the amorphous silicon nitride powder in the present invention.

Specific examples of metal oxides that make up glass include:

At203, 8102, Y2O3, La2O3,
MfO, TiO2, CaO.

Examples include Nano and the like, but are not limited to these. In addition, materials that generate oxides of the metals through thermal decomposition during the glass production process may also be used, as nine examples:
Examples include carbonates, basic carbonates, organic acid salts such as oxalic acid, hydroxides, etc. of these metals, but are not limited to these.

The amorphous silicon nitride and the glass-forming compound are preferably mixed in such a proportion that the nitrogen content in the nitrogen-containing glass in the product is from 2 to 20 atoms, particularly from 5 to 20 atoms. As nitrogen content increases.

As the glass formation temperature shifts to the high temperature side, the hardness increases.

The strength and refractive index also increase. When the nitrogen content is reduced by two atoms, the characteristics of a nitrogen-containing glass are almost completely lost, and there is no difference in properties compared to oxide glasses.

There is no particular restriction on the method of mixing each raw material, and there are any known methods 9, such as dry mixing, wet mixing in an inert medium that does not substantially react with each component of the raw materials, and then
A method of removing an inert medium, etc. can be adopted.

As a mixing device.

V-type mixers, ball mills, vibrating ball mills, etc. are preferably used. As an alternative method of preparing mixed powders.

It is also possible to adopt a method in which a glass-forming compound is mixed and dispersed in an amorphous silicon nitride precursor 1, such as silicon diimide or silicon tetraamide, and the dispersion is heat-treated. In these mixing methods.

Amorphous silicon nitride powder or its precursors are extremely sensitive to water and oxygen and require handling under a controlled inert atmosphere.

Prior to heating and melting, it is preferable to form a molded article into a desired shape using a mixture of raw material powders.

As a method for manufacturing the molded body, a method of putting the raw material powder into a mold and uniaxial press molding, a method of further performing rubber press molding after -axial press molding, etc. can be adopted.

In the present invention, a mixed powder or a compact thereof is heated and melted in a nitrogen-containing gas atmosphere to obtain a nitrogen-containing glass.

An example of a nitrogen-containing gas atmosphere is nitrogen gas.

Examples include an ammonia gas atmosphere and an argon gas atmosphere containing these.

The heating temperature is preferably 1400 to 1800°C.

If the heating temperature is 1400°cxp lower, it will not melt sufficiently.

It becomes difficult to obtain homogeneous glass. Further, when the temperature exceeds 1800°C, thermal decomposition causes scattering of SIO, N2 gas, etc., and glass with a composition deviated from the desired composition is produced. The heating time is 5 to 180 minutes, preferably 30 to 60 minutes.

The quenching rate after heating is 10-6000°C/min, especially 30°C/min.
It is preferable that it is 0-2000 degreeC/min.

If the quenching rate is less than 10'/min, the glass tends to become crystallized glass, and if the quenching rate is more than 6,000°, the glass tends to break due to thermal stress during cooling.

〔Effect of the invention〕

According to the present invention, compared to conventional oxide glasses, strength,
Nitrogen-containing glass with high hardness, high refractive index, and excellent heat resistance can be easily produced on an industrial scale. Furthermore, the nitrogen-containing glass produced in this manner is more likely to be homogeneous and large in size with less unevenness than the glass produced by the conventional method.

〔Example〕

The present invention will be specifically explained below with reference to Examples, but the present invention is not limited thereto.

Example 1 Amorphous silicon nitride powder 13,09, Y2O382,0? obtained by heat-treating silicon diimide at 1200°C. and 5iO25,Of were mixed for 1 hour in a vibrating ball mill under a nitrogen gas atmosphere. The obtained mixed powder is approximately 20 mm in diameter
Molding was performed using a 5rLrIn mold at a pressure of 150Kq/-. Place the molded body in a boron nitride crucible.

Under a nitrogen gas atmosphere, from room temperature to 1200'C for 1 hour, and from 1200'C to 1400°C for 4 hours.

Another 2 hours from 1400°C to 1600°C.

After being melted by holding at 1600°C for 1 hour, 100
A nitrogen-containing glass was obtained by rapidly cooling to 1000'C in 7 minutes at 0'C. Its nitrogen content was 11.5 at%.
(Theoretical amount was 13.7 at%).

Examples 2 to 4 Raw materials having the respective compositions shown in Table 1 were vitrified in the same manner as in Example 1. The nitrogen content of the obtained nitrogen-containing glass is shown in Table 1.

Chapter 1 Table

Claims (1)

[Claims] 1. Metal oxides constituting amorphous silicon nitride powder and glass or metal salts that become the metal oxides through thermal decomposition.
A method for producing nitrogen-containing glass, which comprises heating and melting a mixture of at least one species in a nitrogen-containing gas atmosphere and then rapidly cooling the mixture. 2. The method for producing a nitrogen-containing glass according to claim 1, wherein the nitrogen content is 2 to 20 atomic %.