WO2003018506A1

WO2003018506A1 - Mixed sintered compact of silicon and silicon dioxide and method for preparation thereof

Info

Publication number: WO2003018506A1
Application number: PCT/JP2002/006882
Authority: WO
Inventors: Yoshitake Natsume; Tadashi Ogasawara; Toshiharu Iwase
Original assignee: Sumitomo Titanium Corporation
Priority date: 2001-08-22
Filing date: 2002-07-05
Publication date: 2003-03-06
Also published as: JPWO2003018506A1

Abstract

A mixed sintered compact of silicon and silicon dioxide, which is prepared from a silicon powder and a silicon dioxide powder and has a bulk density which is 75 % or more relative to that to be obtained when the raw material powders are packed at 0 % porosity and a Vickers hardness of 100 or more; and a method for preparing the mixed sintered compact of silicon and silicon dioxide which comprises mixing a silicon powder and a silicon dioxide powder, and then pressing and sintering the mixed material under vacuum, at a pressure of a press of 15 to 20 MPa, at a temperature of 1350 to 1420˚C, and for a period of one hour or more. The mixed sintered compact has an advantage of the use of a silicon powder and a silicon dioxide powder as raw materials, and also exhibits an enhanced speed in the formation of a silicon monoxide vapor deposition film, is significantly reduced in the occurrence of splashing and is almost free from cracking or chipping even when it is machined into a desired shape.

Description

Specification

TECHNICAL FIELD The present invention relates to a mixed sintered body of silicon and silicon dioxide, and a method for producing the same.

The present invention relates to a mixed sintered body of silicon and silicon dioxide, which is used for producing a gas barrier film and a silicon oxide vapor-deposited film which are optimal as a packaging material for foods, medical products, pharmaceuticals, and the like. It relates to a manufacturing method. Background art

In the field of food packaging, there is a demand for prevention of deterioration of fats and oils and proteins contained therein, that is, suppression of deterioration in quality due to oxidation caused by oxygen, water vapor, aromatic gas, and the like permeating the packaging material.

In addition, medical products and pharmaceuticals are required to suppress the deterioration and deterioration of the contents with higher standards.

Therefore, packaging materials for foods, medical products, pharmaceuticals, etc. are required to have a high gas barrier property against permeation of oxygen, water vapor, aromatic gas, etc., which deteriorate the quality of the contents.

As a packaging material having such a high gas barrier property, there is a vapor deposition film in which silicon oxide is vapor-deposited on a polymer film. In particular, silicon monoxide vapor-deposited films having excellent gas barrier properties against oxygen, water vapor, aromatic gas and the like have been attracting attention.

The silicon monoxide vapor deposition material, which is a raw material for forming the silicon monoxide vapor-deposited film, is obtained by mixing silicon powder and silicon dioxide powder, and reacting and producing the mixture in a high-temperature vacuum atmosphere. The vapor deposition material is manufactured by condensing elementary gas on the deposition substrate. This manufacturing method is called a vacuum condensation method. Vapor deposition materials for silicon monoxide produced by the vacuum condensing method are expensive because they are produced through many steps, and have problems in that the structure in the thickness direction is not uniform. In detail, there is no problem in the vicinity of the surface of the deposition material deposited last on the deposition substrate, but the portion deposited first on the deposition substrate has a needle-like structure, and this portion is formed on the film as the deposition material. When a film is formed, a problem that a splash phenomenon occurs frequently occurs.

On the other hand, as an inexpensive method for producing silicon monoxide vapor deposition material, silicon powder, silicon dioxide and silicon powder are dry-mixed, press-formed, and sintered. A proposal has been made as a material (JP-A-63-310961). According to this sintering method, it can be manufactured at a relatively low cost, but the bulk density is low and the splash phenomenon cannot be sufficiently suppressed.

Also, Japanese Patent Application Laid-Open No. 6-57417 discloses that a raw material obtained by adding a binder to a mixed powder of silicon powder and silicon dioxide powder and sintering the mixed powder is 95% of the specific gravity of the mixed powder raw material. It has been proposed to obtain a sintered body having an apparent specific gravity (bulk density).

The vapor deposition material for silicon monoxide obtained by a conventional vacuum condensation method, and the vapor deposition material obtained by mixing silicon powder and silicon dioxide powder in a dry manner, pressing, compacting, and then sintering are as follows: However, the generation of splash could not be sufficiently suppressed.

In the case of the latter sintering method, the sublimation and film formation occur after the reaction between silicon and silicon dioxide by heating to produce silicon monoxide. is there.

In the case of the sintering method in which a binder is added and granulated, the bulk component is filled with a porosity of 0% because the binder component remains in the gap between the silicon and silicon dioxide particles even after sintering. The bulk density is 95% of the bulk density obtained when the raw material is removed, but if the remaining binder is removed, the bulk density is considered to be only about 60% of the bulk density obtained when the raw material is filled with a porosity of 0%. On the other hand, in some cases, the material is machined because it is necessary to match the shape of the evaporation material to the shape of the target holding section of the evaporation apparatus used. However, the vapor deposition material for silicon monoxide obtained by the conventional vacuum condensing method or obtained by mixing the raw material powders in a dry manner, pressing, molding and sintering, often causes cracks and chips during processing. It was difficult to machine into the shape. Disclosure of the invention

The present invention relates to a film forming method using a sintered body composed of a mixture of raw material, elementary powder and carbon dioxide, and elemental powder as a vapor deposition material for silicon monoxide. It is an object of the present invention to provide a mixed sintered body of silicon and silicon dioxide which can achieve such an object, and a method for producing the same.

As described above, when a vapor deposition material for silicon monoxide is used for the production of a vapor deposition film by a vacuum condensation method, a vapor deposition film can be formed only by sublimation by heating, so that the deposition rate is high. On the other hand, when a sintered body obtained from a mixed powder as a raw material is used as the deposition material, sublimation and film formation occur after a silicon oxide gas is generated by a heating reaction. slow.

However, the vapor deposition material for silicon monoxide formed by the vacuum condensing method has a high film forming rate during vapor deposition and is excellent in productivity, but has the disadvantage that it is expensive, raises production costs, and has a non-uniform material structure. is there.

Therefore, the inventors of the present invention have found that, in a sintered body that can be produced at a lower cost than a vapor deposition material for silicon monoxide by a vacuum condensation method and has a high homogeneity, a film forming rate and a low brushing rate are not inferior to those by the vacuum condensation method. As a result of various investigations for the purpose of forming a vapor-deposited material capable of obtaining good properties, it was found that a high film forming rate and low splash property can be obtained by specifying the bulk density and Vickers hardness of the sintered material. Was completed. That is, the present invention is a sintered body using silicon powder and silicon dioxide powder as raw materials, and has a bulk density of 75% or more with respect to a bulk density when the raw materials are filled with a porosity of 0%. A mixed sintered body of silicon and silicon dioxide, characterized by having a hardness of at least 100.

In addition, the present invention provides a mixed material comprising silicon powder and silicon dioxide powder, and pressurizes and sinters in a vacuum atmosphere at a pressing pressure of 15 to 20 MPa, a heating temperature of 1350 to 1420 ° C, and a holding time of 1 hour or more. A method for producing a mixed sintered body of silicon and silicon dioxide, characterized by increasing the area of a particle contact portion between the silicon powder and the silicon dioxide powder and bonding them. Description of the drawings

FIG. 1 is an explanatory diagram of a hot press apparatus used in the method for producing a mixed sintered body according to the present invention.

FIG. 2 is a graph showing an X-ray diffraction result of the mixed sintered body according to the present invention. FIG. 2A shows a case of a mixed powder, and FIG. 2B shows a case of a mixed sintered body.

FIG. 3 is an explanatory diagram of a configuration of a vacuum evaporation apparatus used in the example. BEST MODE FOR CARRYING OUT THE INVENTION

In the present invention, the raw material silicon powder and silicon dioxide powder are not particularly limited. Although the purity varies depending on the application, the purity is preferably 99.9% or more. The form is not particularly limited, but may be ordinary pulverized powder. The smaller the average particle size is, the more preferable it is. In the present invention, as a method of uniformly mixing the silicon powder and the silicon dioxide powder, a known ball mill, a V-type mixer, a machine-expansion mixer, or the like can be used. When heating mixed powders of raw powder, raw powder, raw powder, and raw powder in a vacuum atmosphere, they start to react violently from around 1300 ° C and generate silicon monoxide gas, which results in sintering. It is difficult. Therefore, conventionally, when heating the above mixed powder in a vacuum atmosphere, it has been considered that the temperature must be about 1250 ° C or lower, which is lower than the reaction starting temperature of 1300 ° C.

However, the inventors found that even at a temperature exceeding 1300 ° C, which is the reaction starting temperature of the mixed powder material of silicon powder and silicon dioxide powder, the sintering was performed by applying a pressure of 15 MPa or more with a hot press. It has been found that a mixed sintered body which suppresses the generation of silicon monoxide gas and has a high bulk density and a high Vickers hardness can be obtained.

Specifically, silicon powder is obtained by pressing and sintering a mixed material of silicon powder and silicon dioxide powder at a heating temperature of 1350 to 1420 ° C under a pressurization of 15 to 20 MPa in a vacuum atmosphere. Sintering can be performed by enlarging the area of the particle contact portion between the silicon dioxide powder and the silicon dioxide powder, and a mixed sintered body having high bulk density and hardness can be obtained.

The obtained mixed sintered body has a bulk density of 75% or more with respect to the bulk density when the above-mentioned raw material is filled with a porosity of 0%, and has a characteristic of a Pickers hardness of 100 or more. It is.

In general, the reaction of silicon (Si) and silicon dioxide (Si0 ₂₎ is initiated either et contacting portion between solids. At this time, the reaction time is shortened in inverse proportion to the increase in the area occurring reaction force (Si and Si0 ₂ of contact surface product).

The mixed sintered body according to the present invention is characterized in that the sintering is performed while maintaining the pressing pressure at a high level and in a range, thereby increasing the contact area between the elementary powder and the oxide powder and the elementary powder. And As a result, a high film forming rate can be obtained when a silicon oxide film is formed by a vapor deposition method.

Generally, the bulk density of a sintered body is represented by the ratio of the density of the obtained sintered body to the true density of the sintered body. In the case of alloys, the true density of the alloy formed by sintering is If used, the bulk density can be calculated. However, in the case of the present invention, unlike the alloy sintered body, as is clear from the X-ray diffraction of the examples, most of the raw material silicon powder and silicon dioxide powder remain in the silicon and dioxide after sintering. It is presumed that the silicon crystal exists without change and only the contact parts of the particles are bonded. Therefore, unlike the case of alloy sintering, the bulk density of the sintered body cannot be determined based on the true density of the alloy.

Therefore, in the present invention, it is considered that the case where the mixed raw material of the raw material silicon powder and the silicon dioxide powder is filled with the porosity of 0% (filling rate of 100%) is equivalent to the true density. The bulk density of the sintered body was represented by a comparative value based on It is hard to imagine that the porosity actually becomes 0%, but it is a calculated value to be used as a reference. It can be calculated from the number of moles or mole ratio of specific gravity 2.33 and Si0 ₂ specific gravity 2.60 and respective raw material powders of Si.

To identify the material molar ratios of the sintered body, first, by checking the peaks of Si and Si0 ₂ a sintered body by X-ray diffraction, the sintered body is mainly Si and Si0 ₂ sintered body Make sure that Then, be added finely ground to hydrofluoric acid sintered body, Si remains all the dissolved only Si0 _2. Thus the mass of the mass and grinding prior to sintering of the resulting Si, so the mass ratio of the sintered body of Si and Si0 ₂ is known, it is possible to know the molar ratio of Si and Si0 _2. Si and Si0 ₂ molar ratio of the sintered body is in order to obtain a sufficient reaction rate, it is necessary to satisfy the equation (1) below. More preferably, it is desirable to satisfy the following two equations.

0.90≤ mol (Si) / mol (Si02) ≤ 1.10 1 formula

0.95≤ mol (Si) / mol ( Si0 2) ≤ 1.05 2 expression

In the mixed sintered body according to the present invention, it is considered that some kind of reaction such as sintering occurs at the contact point between the element, the elementary powder and the dioxide, and the contact point between the elementary powder. When the Si0 ₂ in the height of the peak, even when compared with the sintered before sintering, most because it is the same, most of the silicon and silicon dioxide raw material after sintering also it It was found that each of them did not change in a crystalline state. Accordingly, a thickness even above method after sintering, it is possible to know the molar ratio of Si and Si0 _2.

In the mixed sintered body of silicon and silicon dioxide according to the present invention, the bulk density is at least 75% of the bulk density when the above mixed raw material is filled with a porosity of 0%, and the pick hardness is at least 100. The condition was that the sintered body as a vapor deposition material was not inferior to the vapor deposition material for silicon monoxide by the vacuum condensation method. This is based on the results of experiments that determined conditions that are equivalent or higher.

Then, the present inventors have developed a pressurizing and sintering condition (hereinafter referred to as a hot pressing condition) capable of obtaining a mixed sintered body of silicon, silicon dioxide and silicon having the above characteristics, and a heat temperature of 1350 °. The above experiment confirmed that the press pressure had to satisfy 15 MPa or more at C or more.

The vacuum atmosphere is not particularly limited, but it is preferable to use an inert gas atmosphere when processing at a low vacuum.

If the heating temperature exceeds 1420 ° C, silicon will dissolve, so the heating temperature

1350 to 1420 ° C is preferable. More preferably, it is 1375 ° C to 1400 ° C.

Pressing pressure of up to 20 MPa is sufficient, so a range of 15 to 20 MPa is preferable.

Also, the holding (sintering) time of the hot press must be at least 1 hour. Preferably, it is 1 to 2 hours.

In the present invention, any known configuration can be adopted for the hot press apparatus for sintering under the above hot press conditions. For example, as shown in FIG. 1, a heater 1 is provided in a chamber 1 so that heating can be performed. A sleeve 4 is inserted and arranged in a die 3 disposed in the heater 2. The mixed powder 7 of the raw material is filled in the space formed by fitting the upper and lower punches 5 and 6 into the space, and the press shaft 8 is operated to pressurize and sinter. After the sintering under the hot press conditions, the temperature of the obtained mixed sintered body was lowered until the obtained mixed sintered body was taken out. The temperature was gradually cooled in the furnace to the room temperature (furnace cooling), in order to improve the productivity. For example, after cooling the furnace to 600 ° C, it is also possible to forcibly cool from 600 ° C to room temperature with an inert gas such as argon. Example

The particle size of the raw material is 1 ~ 15μπι for silicon powder, and particle size for silicon dioxide powder.

The mixture was changed in the range of 3 to 20 μπι, weighed to a predetermined mixing ratio, and mixed with a ball mill.

Using the hot press shown in Fig. 1, press at a pressure of 15 to 20 MPa and pressurize, and change the heating temperature at 1350 to 1420 ° C, pressurize and sinter under a holding time of 1 hour. Then, a mixed sintered body of silicon and silicon dioxide was obtained (Examples 1 to 6). For comparison, pressurization was performed by changing the press pressure at 10 to 15 MPa, and the heating temperature was changed at 1300 to 1450 ° C. (Comparative Examples 1 to 4).

Table 1 shows the hot press conditions. Table 2 shows the results of measuring bulk density and Vickers hardness by taking samples from the obtained sintered bodies.

FIG. 2A shows an X-ray diffraction result in the state of the mixed powder, and FIG. 2B shows an X-ray diffraction result of the mixed sintered body (15 MPa, held at 1400 ° C. for 1 hour) according to the present invention. It is clear that the silicon and silicon dioxide crystals still exist and remain unchanged afterwards, and only the contact portions of the particles with each other are joined.

Further, using a vacuum evaporation apparatus 10 shown in FIG. 3, the obtained mixed sintered body was used as an evaporation material 11, and a silicon monoxide film was formed on a polymer film arranged in a holder 12 by film formation. The speed and the occurrence of the splash phenomenon were investigated. Table 2 shows the results. The bulk density (%) in the table is a comparison value with respect to the bulk density when the mixed raw material is filled with a porosity of 0%. The film formation rate was compared based on the case where good quality silicon monoxide produced by the vacuum condensation method was used as the deposition material.

In Comparative Example 4 in which the heating temperature during sintering was 1450 ° C, no sintered body was obtained because silicon was dissolved.

From the results in Table 2, it can be seen that the mixed sintered bodies manufactured by satisfying the hot pressing conditions of the heating temperature of 1350 to 1420 ° C and the pressing pressure of 15 to 20 MPa according to the present invention have a bulk density of 75% or more of the true density. It has a Vickers hardness of 100 or more, the film forming speed at the time of vapor deposition is the same as that of the material deposited by the vacuum condensation method, and it can be seen that the film has excellent characteristics with little occurrence of a splash phenomenon.

On the other hand, the comparative examples which do not satisfy the hot press conditions of the present invention all have a bulk density of less than 75% of the true density and a Vickers hardness of less than 100, and have a higher deposition rate than the vapor-deposited material by the vacuum condensation method. It is clear that the production is not expected because it is slow and generates many splashes, which is economically efficient.

Hot pressing conditions

Si Si0 ₂ heating temperature holding time pressing pressure, Myuiotaita Roh)

1

丄 1 3 1350 15

¹¹

Real

Δ o 1 3 1380 20 Al 3 1 3 1420 20

4 1 3 1350 20 Example

5 8 9 1350 15

6 15 20 1350 15

1 1 3 1 300 15 Ratio

Comparison 2 1 3 13 20 15 Example 3 1 3 1 350 10

4 1 3 1450 15

Industrial applicability

The mixed sintered body according to the present invention is manufactured using only the swarf, the elementary powder and the dioxide, and the elementary powder, and does not contain a binder component or the like. In addition, since the mixed sintered body has a hardness of at least 100, cracks and chips are hardly generated even when machining into a desired shape.

When the mixed sintered body according to the present invention is used as a vapor deposition material for elementary metal, and is deposited on a polymer film or the like, the film forming rate is equivalent to that of the elementary vapor-deposited material obtained by the conventional vacuum condensation method. And the occurrence of a splash phenomenon during film formation can be significantly reduced.

Claims

The scope of the claims

1. A sintered body using silicon powder and silicon dioxide powder as raw materials, having a bulk density of 75% or more of the bulk density when the above raw materials are filled with a porosity of 0%, and a Vickers hardness A mixed sintered body of silicon, silicon dioxide, and silicon with a power of ^ 'ΙΟΟ or more.

2. Using a mixture of silicon powder and silicon dioxide powder as raw materials, pressurizing and sintering in a vacuum atmosphere at a press pressure of 15 to 20 MPa, a heating temperature of 1350 to 1420, and a holding time of 1 hour or more, and porosity of the above raw materials. A method for producing a mixed sintered body of silicon and silicon dioxide having a bulk density of 75% or more with respect to the bulk density when filled with 0%, and a sintered body with a Picker hardness of 100 or more. .

3. The method for producing a mixed sintered body of silicon and silicon dioxide according to claim 2, wherein the holding time is 1 hour to 2 hours.