JP6959790B2 - Sintering method and manufacturing method of sintered product - Google Patents

Description

The present invention relates to a method for sintering ceramics for sintering, and a method for producing a sintered product using the same.

For example, in the case of producing a plate-shaped ceramic sintered body, a slurry, paste or powder prepared by mixing ceramic particles and a binder solution in which a polymer binder is dissolved in a medium is press-molded and the slurry is cast. , Injection molding, extrusion molding, screen printing, etc., and then firing treatment is applied. Among these, a method for producing a ceramic sintered body on a base material is disclosed in Patent Document 1, and as a method for producing a sheet-shaped ceramic, a water-soluble binder, a ceramic powder, and water are included. A method of casting a ceramic slurry composition having a volume solid content ratio of 2% or more and less than 5% on a support to form a sheet, and drying, degreasing, and firing the ceramic slurry is described.

Japanese Unexamined Patent Publication No. 2004-315307

When the ceramics for sintering are directly irradiated with a laser, they cannot be sufficiently sintered. For example, when the surface of a ceramic plate for sintering is irradiated with a laser to sufficiently grow grains, the length is long. Irradiation for hours was essential. Therefore, the present inventors have been studying whether it is possible to form a layer containing carbon powder on the surface of a ceramic plate for sintering and irradiate it with a laser to promote sintering.
An object of the present invention is a method for efficiently sintering ceramics for sintering, and an article having a non-sintered portion made of ceramics for sintering (hereinafter, also referred to as "raw material article"). It is an object of the present invention to provide a method for efficiently producing an article having a desired portion as a sintered portion (hereinafter, also referred to as a "sintered product" whether the sintered portion is a part or the whole).

Further, when a laser is irradiated with a layer containing carbon powder formed on a thin plate or a ceramic part for sintering which constitutes a layer, cracks or cracks may occur due to thermal shock. Another object of the present invention is to provide a method for sintering and a method for producing a sintered product without causing defects such as cracks and cracks.

The present invention is shown below.
1. 1. A layer containing carbon powder is formed on the surface of an article made of ceramics for sintering, and then the carbon powder-containing layer in the obtained laminate is irradiated with a laser under an inert gas atmosphere or vacuum conditions. A method for sintering ceramics for sintering, which comprises.
2. Item 2. The sintering method according to Item 1, wherein the sintering ceramic is at least one selected from oxides, nitrides and oxynitrides.
3. 3. Item 2. The sintering method according to Item 1 or 2, wherein the wavelength of the laser is 400 nm to 11 μm.
4. The sintering method according to any one of Items 1 to 3, wherein a laser transmitting member is placed on the surface of the carbon powder-containing layer.
5. Item 4. The sintering method according to Item 4, wherein the laser transmitting member contains quartz glass.
6. In the step of forming a layer containing carbon powder on the surface of the non-sintered portion of the article provided with the non-sintered portion made of ceramics for sintering, and in the obtained laminate under the condition of an inert gas atmosphere or vacuum. A method for manufacturing an article having a sintered portion, which comprises sequentially providing a step of irradiating the carbon powder-containing layer with a laser to sinter the ceramics for sintering located on the base side of the irradiated portion. ..
7. Item 6. The production method according to Item 6, wherein the sintering ceramic is at least one selected from oxides, nitrides and oxynitrides.
8. Item 6. The production method according to Item 6 or 7, wherein the wavelength of the laser is 400 nm to 11 μm.
9. The production method according to any one of Items 6 to 8 above, wherein the laser transmitting member is placed on the surface of the carbon powder-containing layer.
10. Item 9. The manufacturing method according to Item 9, wherein the laser transmitting member includes quartz glass.

According to the sintering method of the present invention, the ceramics for sintering can be sintered in a shorter time. Further, according to the sintering method of the present invention, in an atmosphere containing oxygen gas, the carbon powder-containing layer formed on the surface of the ceramics for sintering is irradiated in the depth direction from the surface as compared with the case of irradiating the laser. A fully grown sintered product can be obtained.
In addition, when irradiating a thin plate or a ceramic part for sintering that constitutes a layer with a laser, by placing a laser transmitting member on the surface of the carbon powder-containing layer, cracks, cracks, etc. occur due to the laser irradiation. Can be suppressed.

It is a schematic cross-sectional view which shows an example of the sintering method of this invention and the manufacturing method of the sintered matter of this invention. It is schematic cross-sectional view which shows the other example of the sintering method of this invention and the manufacturing method of the sintered matter of this invention. It is the schematic which shows the method of scanning the laser irradiation to the surface of the ceramic plate for sintering in Examples 1 and 2 and Comparative Example 1. 6 is an SEM image showing a cross section of the surface layer portion on the laser irradiation portion side of the sintered product obtained in Comparative Example 1. 5 is an XRD diffraction image of the surface layer portion on the laser irradiation portion side of the sintered product obtained in Example 1 and Comparative Example 1. 6 is an SEM image showing a cross section of the surface layer portion on the laser irradiation portion side of the sintered product obtained in Example 1. 6 is an SEM image showing the surface of the laser-irradiated portion of the sintered product obtained in Example 2. 6 is an SEM image showing a cross section of the surface layer portion on the laser irradiation portion side of the sintered product obtained in Example 2. 6 is an SEM image showing the surface of the laser-irradiated portion of the sintered product obtained in Example 3. 6 is an SEM image showing a cross section of the surface layer portion on the laser irradiation portion side of the sintered product obtained in Example 3.

In the sintering method of the present invention, a layer containing carbon powder is formed on the surface of an article made of ceramics for sintering, and then the carbon powder is contained in the obtained laminate under an inert gas atmosphere or vacuum conditions. It is characterized by irradiating the layer with a laser.

FIG. 1A shows a laser irradiating a predetermined position of a carbon powder-containing layer 14 formed on the surface of an article 12 made of sintering ceramics in a chamber 20 under an inert gas atmosphere or a vacuum condition. It is explanatory drawing, and FIGS. It is explanatory drawing which shows that. When the carbon powder-containing layer 14 in the laminate 10 composed of the article 12 and the carbon powder-containing layer 14 is irradiated with a laser, the carbon powder absorbs the energy of the laser and generates heat in the laser irradiation portion, but the atmosphere is an inert gas or Since the laser irradiation is performed under vacuum conditions, it does not disappear. Then, the carbon powder-containing layer 14 serving as a heat source heats the ceramics for sintering on the base side to 800 ° C. or higher (estimated temperature) to promote the crystal growth of the particles to form the sintered portion 16. The sintering depth can be adjusted according to the thickness of the article 12, the laser irradiation conditions, and the like, and for example, the sintered portion 16 shown in FIGS. 1B or 1C can be obtained.

The sintering ceramics constituting the article 12 are preferably oxides, nitrides, oxynitrides and the like, and of these, only one type may be used, or two or more types may be used.
As the oxide, aluminum oxide, murite, magnesium oxide, zinc oxide, titanium oxide, iron oxide, yttrium oxide, zirconium oxide, barium titanate and the like can be used.
As the nitride, silicon nitride, aluminum nitride, titanium nitride, zirconium nitride, tantalum nitride, iron nitride and the like can be used.
As the oxynitride, sialon, silicon oxynitride and the like can be used.

The article 12 is preferably composed of an aggregate of ceramic particles for sintering. In this case, the shape and size of the particles are not particularly limited. The particle shape can be a medium substance, a spherical shape, an elliptical spherical shape, a polyhedral shape, a linear shape, a plate shape, an indefinite shape, or the like. The average particle size of the particles is preferably 10 nm to 100 μm, more preferably 100 nm to 10 μm. The density of the particles contained in the article 12 is preferably 40% by volume or more, more preferably 70% by volume or more, from the viewpoint of the strength of the sintered portion to be formed, the sintering time, and the like.

The shape of the article 12 is not particularly limited, and may be a flat plate shape, a curved plate shape, a rod shape, a tubular shape, a lump shape, a combination thereof, or a deformed shape thereof. The portion irradiated with the laser may have a concave portion or a convex portion.
The article 12 is dried after being coated with a slurry containing a thermal spraying method, an electron beam physical vapor deposition method, a laser chemical vapor deposition method, a cold spray method, ceramic particles for sintering, a dispersion medium and a polymer binder used as necessary. It can be obtained by a conventionally known method such as a method of further degreasing.

The method for forming the carbon powder-containing layer 14 on the surface of the article 12 is not particularly limited. Using only carbon powder, a composition containing carbon powder and a binder, or a composition containing carbon powder and an organic solvent, a spraying method such as spraying, a printing method such as screen printing, a doctor The carbon powder-containing layer 14 can be formed at a desired position (part or the entire surface) on the surface of the article 12 by a coating method such as a blade method, a spin coating method, or a curtain coater method. The atmosphere for forming the carbon powder-containing layer 14 may be either air or an inert gas.
The content ratio of the carbon powder contained in the carbon powder-containing layer 14 is preferably 50% by mass or more, more preferably 80% by mass or more, from the viewpoint of smooth sinterability.

The thickness of the carbon powder-containing layer 14 is not particularly limited, but is preferably 5 nm to 30 μm, more preferably 100 nm to 10 μm from the viewpoint of smooth sinterability.

When irradiating the carbon powder-containing layer 14 with a laser, it is preferable to use a laser having a wavelength of 500 nm to 11 μm from the viewpoint of smooth sinterability. For example, Nd: YAG laser, Nd: YVO laser, Nd: YLF laser, titanium sapphire laser, carbon dioxide gas laser and the like can be used.

The laser irradiation conditions are appropriately selected depending on the type of ceramics for sintering, the sintering area, the sintering depth, and the like. Laser power, in terms of smooth sinterability, preferably 50~2000W / cm ^2, more preferably 100 to 500 W / cm ^2. The irradiation time is preferably 1 second to 60 minutes, more preferably 5 seconds to 30 minutes.
In the present invention, the atmosphere when the carbon powder-containing layer 14 is irradiated with the laser is an inert gas atmosphere or a vacuum in which the content of oxygen gas is suppressed as much as possible. Examples of the inert gas include nitrogen, argon, helium and the like.
When irradiating the laser, the article 12 or the carbon powder-containing layer 14 before irradiation may be preheated. When preheating, the temperature is preferably 300 ° C. or higher, more preferably 400 ° C. or higher, and the upper limit is usually 200 ° C. or higher lower than the melting point of the ceramics for sintering. The preheating method is not particularly limited, and may be an infrared lamp, a halogen lamp, resistance heating, high frequency induction heating, microwave heating, or the like.
When the entire surface of the carbon powder-containing layer 14 in the laminate 10 is irradiated with the laser, the entire surface of the carbon powder-containing layer 14 on the base side of the laser-irradiated portion can be the sintered portion 16. In the case of sintering a large area with respect to the above, a method of irradiating while scanning a laser with the laminate 10 fixed or changing the optical path through a light diffusing lens, or while moving the laminate 10. , A method of irradiating a laser with a fixed optical path can be applied.

When the laser is applied not only to the carbon powder-containing layer 14 in the laminate 10 but also to the sintering ceramics on which the carbon powder-containing layer is not formed, the higher the energy integration amount, the more sufficient it is in the depth direction. Sintering can proceed. However, sufficient grain growth occurs from the surface to the surface layer to a depth of, for example, 10 μm or more, or the base side of the irradiation portion in the carbon powder-containing layer, and the entire cross-sectional portion extending from one surface side to the other surface side. The irradiation time for obtaining the sintered product is very different. The method of the present invention is a method of irradiating the sintering ceramics on which the carbon powder-containing layer is not formed with a laser, and an atmosphere in which the laminate 10 provided with the carbon powder-containing layer 14 contains oxygen gas. It is useful because it can be shortened in a shorter time than the method of irradiating a laser.

When the above laser irradiation conditions are applied to, for example, the flat plate-shaped laminate 10, sintering can be efficiently performed to a depth of about 300 μm from the surface. Therefore, a method of irradiating while scanning a laser with the laminate 10 fixed or changing the optical path through a light diffusing lens, or a method of irradiating a laser with a fixed optical path while moving the laminate 10. Also, in a specific portion, sintering can be performed from the surface to a desired depth.

As described above, the article 12 can have various shapes, but for example, when a thin-walled portion having a thickness of 0.1 mm or less is irradiated with a laser, cracks or cracks occur in the laser-irradiated portion. I have something to do. In order to suppress such a defect, as shown in FIG. 2, it is preferable to place the laser transmitting member 40 on the surface of the carbon powder-containing layer 14 in the laminate 10. Then, in order to maintain the shape of the article 12, the laser transmitting member having a structure along the surface shape of the article 12 even if it has a convex portion or a concave portion regardless of the surface shape of the article 12 irradiated with the laser. It is particularly preferable to use 40.

The constituent material of the laser transmitting member 40 is not particularly limited, but quartz glass is preferable.

The method for producing a sintered product of the present invention includes a step of forming a layer containing carbon powder on the surface of the non-sintered portion of an article (raw material article) including a non-sintered portion made of ceramics for sintering, and an inertness. A step of irradiating a carbon powder-containing layer in the obtained laminate under a gas atmosphere or a vacuum condition to sinter the ceramics for sintering located on the base side of the irradiation portion is sequentially provided. As described above, the sintering ceramics constituting the non-sintered portion of the raw material article can be oxides, nitrides, oxynitrides and the like. The method of forming a carbon powder-containing layer on the surface of the non-sintered portion of the raw material article and the laser irradiation method (laser type, wavelength, irradiation conditions, atmosphere, etc.) are also as described above.

As described above, according to the present invention, it is possible to produce a sintered product in which grains are sufficiently grown from the surface in the depth direction.

Hereinafter, embodiments of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

Comparative Example 1
Α-type aluminum oxide particles having a particle diameter in the range of 1 to 5 μm were pressure-molded to obtain disc-shaped sintering ceramics having a diameter of 10 mm and a thickness of 2 mm. Then, the aerosol dry graphite film forming lubricant "DGF Spray" (trade name) manufactured by Nippon Ship Tools Co., Ltd. was sprayed on the surface of the disk-shaped sintering ceramics for about 1 second. Then, this was left to stand for 30 seconds to obtain a laminate having a carbon powder-containing layer having a thickness of about 5 μm.
Next, as shown in FIG. 1 (A), the laminate (10) was placed on a pedestal (25) made of SUS304. Then, the inside of the chamber (20) is made into an atmospheric atmosphere, and a laser having a wavelength of 1064 nm and an output of 300 W is emitted from the light source (30) of the Nd: YAG laser arranged directly above the laminate (10). (A), (B), (C), (D), so that the beam diameter is 1000 μm with respect to the surface and at a speed of 500 mm / sec in the direction of the arrow in FIG. 3 for 40 seconds. Irradiation was performed while scanning in the order of (E) .... The distance between (A) and (B) (the same applies to the others) is 0.1 mm, and the irradiation area is 3 mm × 3 mm.
Then, when the laminate was recovered from the chamber (20) and the carbon powder-containing layer was removed, small cracks were observed in the laser-irradiated portion of the sintered body.
The crack-free sintered portion in the laser-irradiated portion was broken, and the surface layer of the sintered portion was observed by SEM (see FIG. 4). According to the image of FIG. 4, it can be seen that in the laser irradiation portion, although aluminum oxide is sintered, the crystals are not clear.
In addition, XRD measurement of the laser irradiation section was performed (see FIG. 5). When the X-ray diffraction image of FIG. 5 was analyzed, it was found that it was α-alumina showing non-orientation.

Example 1
The same operation as in Comparative Example 1 was performed except that the inside of the chamber (20) was made to have an argon gas atmosphere.
Then, when the laminate was recovered from the chamber (20) and the carbon powder-containing layer was removed, small cracks were observed in the laser-irradiated portion of the sintered body.
The crack-free sintered portion in the laser-irradiated portion was broken, and the surface layer of the sintered portion was observed by SEM (see FIG. 6). According to the image of FIG. 6, it can be seen that the laser irradiation portion has sufficiently progressed grain growth and is densified with columnar crystals.
In addition, XRD measurement of the laser irradiation unit (radioactive source: Cu Kα, scanning speed: 2 ° / min, temperature: 25 ° C.) was performed (see FIG. 5). When the X-ray diffraction image of FIG. 5 was analyzed, it was found that it was α-alumina showing orientation on the (104) plane.

Example 2
Α-type aluminum oxide particles having a particle diameter in the range of 1 to 5 μm were pressure-molded to obtain a disk-shaped sintering ceramic having a diameter of 10 mm and a thickness of about 1 mm. Then, the aerosol dry graphite film forming lubricant "DGF Spray" (trade name) manufactured by Nippon Ship Tools Co., Ltd. was sprayed on the surface of the disk-shaped sintering ceramics for about 1 second. Then, this was left to stand for 30 seconds to obtain a laminate having a carbon powder-containing layer having a thickness of about 5 μm.
Next, as shown in FIG. 2A, the laminate (10) is placed on a pedestal (25) made of SUS304, and a quartz glass plate (laser transmission member) having a thickness of 3 mm is placed on the laminate (laser transmission member). It was placed on top of 10). Then, the inside of the chamber (20) is made into an argon gas atmosphere, and a laser having a wavelength of 1064 nm and an output of 300 W is emitted from the light source (30) of the Nd: YAG laser arranged directly above the laminate (10). The surface of the surface was irradiated with a beam diameter of 1000 μm and in the direction of the arrow in FIG. 3 at a speed of 500 mm / sec for 45 seconds while scanning in the same manner as in Example 1.
Then, when the laminate was recovered from the chamber (20) and the carbon powder-containing layer was removed, no cracks or cracks were observed in the laser-irradiated portion of the sintered body.
SEM observation was performed on the surface of the laser-irradiated portion (sintered portion) of the sintered material (see FIG. 7). According to the image of FIG. 7, it can be seen that it is sufficiently sintered.
Further, the laser irradiation portion (sintered portion) of the sintered material was broken, and the surface layer of the sintered portion was observed by SEM (see FIG. 8). According to the image of FIG. 8, it can be seen that the grain growth sufficiently progresses in the range from the surface to a depth of about 300 μm, and the particles are densified with columnar crystals.

Example 3
The laminate (10) prepared in Example 2 was used. As shown in FIG. 2 (A), this laminate (10) is placed on a pedestal (25) made of SUS304, and a quartz glass plate (laser transmitting member) having a thickness of 3 mm is placed on the laminate (10). Placed on top. Then, the inside of the chamber (20) is made into an argon gas atmosphere, and a laser having a wavelength of 1064 nm and an output of 300 W is emitted from the light source (30) of the Nd: YAG laser arranged directly above the laminate (10). The same position on the surface of the surface was irradiated for 30 seconds so that the beam diameter was 10 mm.
Then, when the laminate was recovered from the chamber (20) and the carbon powder-containing layer was removed, no cracks or cracks were observed in the laser-irradiated portion of the sintered body.
SEM observation was performed on the surface of the laser-irradiated portion (sintered portion) of the sintered material (see FIG. 9). According to the image of FIG. 9, it can be seen that it was sufficiently sintered.
Further, the laser irradiation portion (sintered portion) of the sintered material was broken, and the surface layer of the sintered portion was observed by SEM (see FIG. 10). According to the image of FIG. 10, aluminum oxide is sufficiently sintered and densified in the range from the surface to a depth of about 100 μm, and the particle size is in the range of about 100 μm to 300 μm. It can be seen that a densely sintered structure composed of about 20 μm aluminum oxide particles can be seen.

According to the present invention, it is possible to obtain a sintered product in which grains are sufficiently grown in the depth direction from the surface. Therefore, high-temperature members (heat-dissipating members, heat-treating containers, setters, furnace core tubes, temperature-measuring protective tubes, etc.), insulating members, arc tubes, and the like can be efficiently manufactured.

10: Laminate, 12: Article made of ceramics for sintering, 14: Carbon powder-containing layer, 16: Sintered part, 20: Chamber, 25: Pedestal for ceramics for sintering, 30: Laser irradiation means, 40: Laser Transmission member, 50: Article having a sintered portion (sintered product)

Claims (8)

The surface of an article made of sintered ceramics, a layer containing a carbon powder, and then, is irradiated under the conditions of an inert gas atmosphere or vacuum, a laser to the carbon powder-containing layer of the obtained laminate baked In the method of sintering ceramics for connection,
A method for sintering ceramics for sintering, which comprises placing a laser-transmitting member on the surface of the carbon powder-containing layer. The sintering method according to claim 1, wherein the sintering ceramic is at least one selected from oxides, nitrides and oxynitrides. The sintering method according to claim 1 or 2, wherein the wavelength of the laser is 400 nm to 11 μm. The sintering method according to any one of claims 1 to 3, wherein the laser transmitting member includes quartz glass. In the step of forming a layer containing carbon powder on the surface of the non-sintered portion of the article provided with the non-sintered portion made of ceramics for sintering, and in the obtained laminate under the condition of an inert gas atmosphere or vacuum. In a method for manufacturing an article having a sintered portion , the step of irradiating the carbon powder-containing layer with a laser to sinter the ceramics for sintering located on the base side of the irradiated portion is sequentially provided.
A method for producing an article having a sintered portion, which comprises placing a laser-transmitting member on the surface of the carbon powder-containing layer. The production method according to claim 5 , wherein the sintering ceramic is at least one selected from oxides, nitrides and oxynitrides. The production method according to claim 5 or 6 , wherein the wavelength of the laser is 400 nm to 11 μm. The manufacturing method according to any one of claims 5 to 7, wherein the laser transmitting member includes quartz glass.

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