JP2013035715A - Method of producing metal carbide structure and member on the surface of which metal carbide layer is formed - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing a metal carbide structure, by which a metal carbide material is sintered by using microwave while surrounding the metal carbide material with a blanket comprising a mullite, so that the metal carbide structure can be obtained, wherein the surface treatment for the metal carbide structure after sintering is facilitated.SOLUTION: In the method of producing the metal carbide structure, the metal carbide material 11 consisting of a metal carbide is sintered by using the microwave while surrounding the metal carbide material 11 with the blanket 30 comprising the mullite, so that the metal carbide structure 10 can be obtained. The method includes: covering the surface of the metal carbide material 11 with a covering material 20 comprising a carbon and showing a sheet shape having a thickness through which the microwave penetrates; carrying out sintering while the metal carbide material 11 is brought into contact with the inside of the blanket 30 through the covering material 20; and thereafter taking out the metal carbide structure 10 together with the covering material 20 from the blanket 30.

Description

  In the present invention, a metal carbide structure used as a component of a SiC crystal growth apparatus by CVD or a member having a metal carbide layer formed on the surface is manufactured by microwave firing. A metal carbide layer is formed on the surface. It is related with the manufacturing method of the member made.

  Conventionally, examples of the metal carbide structure of this type or a member having a metal carbide layer formed on the surface include a reaction vessel of a SiC crystal growth apparatus by a CVD method and a wall member of a flow path of a gas to be introduced. Here, the member in which the metal carbide layer is formed on the surface is a member in which the inside is made of another material such as metal or ceramic and the metal carbide layer is formed on the surface.

  The SiC crystal growth by this CVD method is performed in a high temperature state of about 1600 ° C. to 2600 ° C. in a reducing atmosphere containing a gas containing Si, a gas containing C, and hydrogen in the reaction vessel. Therefore, as such a metal carbide structure or metal carbide layer, a metal carbide having a high melting point (for example, around 3000 ° C.) such as TiC, TaC, NbC, ZrC, or VC is used.

  Such a metal carbide structure or a member having a metal carbide layer formed on its surface is a metal carbide material made of metal carbide formed by pre-firing or the like, or a material having a metal carbide layer formed on its surface is fired by a microwave firing device. For example, the methods described in Patent Documents 1 to 4 have been proposed.

  Here, generally, a method in which a metal carbide material or a material having a metal carbide layer formed on the surface thereof is surrounded by a blanket made of mullite having a high microwave permeability and a heat insulating effect is performed. Here, mullite contains silica and alumina, and the melting point is usually 2000 ° C. or lower.

  However, in this conventional method, the blanket mullite chemically reacts with the surface of the metal carbide due to the temperature during microwave firing (for example, about 1800 to 2000 ° C.). Then, after taking out the metal carbide structure or the member having the metal carbide layer formed on the surface from the blanket, removing the layer containing mullite from the surface of the metal carbide structure or the member having the metal carbide layer formed on the surface, For example, a process such as polishing was necessary.

  If a large amount of mullite is present on the surface of a metal carbide structure or a member having a metal carbide layer formed on the surface, silica and alumina components in the mullite come out from the surface of the structure during the growth of the SiC crystal, resulting in the SiC crystal. Adhere as a pollutant. Therefore, as described above, it is necessary to perform surface processing by polishing or the like on the sintered metal carbide structure or the member having a metal carbide layer formed on the surface, which is troublesome.

JP 2004-257725 A JP 2003-112983 A JP-A-6-345541 Japanese Patent Laid-Open No. 3-257072

  In the above conventional manufacturing method, simply by separating the blanket made of mullite from the metal carbide material or the material having the metal carbide layer formed on the surface, the chemical reaction between the mullite and the metal carbide or the surface metal carbide layer at the time of firing. Can be suppressed. However, in that case, the heat insulation effect by the blanket made of mullite is insufficient, and the metal carbide material or the material having the metal carbide layer formed on the surface cannot be kept warm, which may make sintering difficult.

  Therefore, conventionally, a blanket and a metal carbide material or a material having a metal carbide layer formed on the surface are brought into contact with each other and sintered after securing heat insulation. Therefore, the chemical reaction with mullite described above is performed. It takes time and effort to process the surface of the sintered metal carbide structure or the member having the metal carbide layer formed on the surface.

  The present invention has been made in view of the above problems, and a metal carbide material or a metal carbide layer is formed on the surface in a state where a metal carbide material or a material on which the metal carbide layer is formed is surrounded by a blanket made of mullite. In a method for producing a metal carbide structure or a member having a metal carbide layer formed on the surface thereof, the sintered metal is sintered in a microwave to form a metal carbide structure or a member having a metal carbide layer formed on the surface. It is an object to facilitate surface processing of a carbide structure or a member having a metal carbide layer formed on the surface.

In order to achieve the above object, according to the first aspect of the present invention, there is provided a metal carbide structure made of a metal carbide used as a component of an SiC crystal growth apparatus by a CVD method or a member (10) having a metal carbide layer formed on the surface thereof. The metal carbide material or the metal carbide layer formed on the surface of the metal carbide material or the surface of the metal carbide material or the material (11) formed with the metal carbide layer formed on the surface surrounded by the blanket (30) made of mullite. In the method for producing a metal carbide structure or a member having a metal carbide layer formed on the surface thereof, which is obtained by sintering the material (11) formed with a microwave to form a metal carbide structure (10),
The surface of the metal carbide material or the material (11) having a metal carbide layer formed on the surface thereof is covered with a coating material (20) made of carbon and having a thickness that allows microwaves to pass through, and this coating material (20). The metal carbide material or the material (11) having a metal carbide layer formed on the surface is brought into contact with the inner surface of the blanket (30) to perform the sintering, and then the metal formed by the sintering. The carbide structure or the member (10) having a metal carbide layer formed on the surface is taken out of the blanket (30) together with the covering material (20).

  Accordingly, the coating material (20) made of carbon has a very high melting point even if it is a thin sheet-like material capable of transmitting microwaves. Therefore, a metal carbide material or a material in which a metal carbide layer is formed on the surface during firing is used. Almost no chemical reaction with the blanket (30) made of (11) or mullite. Therefore, even after taking out from the blanket (30), the amount of mullite adhering to the surface of the covering material (20) is greatly reduced as compared with the conventional case.

  The blanket (30) may be left in a state in which the covering (20) is attached to the sintered metal carbide structure or the member (10) having a metal carbide layer formed on the surface after the blanket (30) is taken out. Absent.

  This is because the metal carbide structure or the member (10) having a metal carbide layer formed on the surface thereof is used as a component of a SiC crystal growth apparatus by CVD, and this crystal growth is performed by using hydrogen as described above. It is performed at a high temperature of about 1600 ° C. to 2500 ° C. in a reducing atmosphere. And in such a state, since the coating material (20) made of carbon is vaporized and removed as hydrocarbons or the like, it does not become a contaminant to the SiC crystal.

  As described above, according to the present invention, the metal carbide material or the material (11) having the metal carbide layer formed on the surface is coated with the coating material (20) and baked, whereby the mullite on the surface of the coating material (20). The amount of adhesion is suppressed, and the coating material (20) itself does not become a contaminant during SiC crystal growth. Therefore, according to the present invention, a conventional process such as polishing after sintering is not required, and surface processing of the sintered metal carbide structure or the member (10) having the metal carbide layer formed on the surface is easy. Can be.

  Here, in the invention according to claim 2, in the method for manufacturing the metal carbide structure according to claim 1 or the member having the metal carbide layer formed on the surface, the metal carbide layer is formed on the metal carbide structure or the surface. After removing the member (10) from the blanket (30) together with the covering material (20), the covering material (20) is peeled off and removed from the metal carbide structure or the member (10) having a metal carbide layer formed on the surface. Features.

  According to this, the blanket (30) attached to the covering material (20) by a simple process of peeling the sheet-like covering material (20) from the metal carbide structure or the member (10) having a metal carbide layer formed on the surface. These components can be removed from the metal carbide structure together with the coating material (20) or from the member (10) having a metal carbide layer formed on the surface.

  In addition, in the method for producing a metal carbide structure according to claim 1 or a member having a metal carbide layer formed on the surface thereof as in the invention according to claim 3, a typical component part of the SiC crystal growth apparatus is used. As a specific shape, the metal carbide structure or the member (10) having a metal carbide layer formed on the surface thereof can be a hollow cylinder.

  In addition, the code | symbol in the bracket | parenthesis of each means described in the claim and this column is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

1 is a schematic external perspective view of a metal carbide structure according to an embodiment of the present invention or a member having a metal carbide layer formed on a surface thereof. It is a figure which shows the flowchart of the manufacturing process of the member which formed the metal carbide structure or the metal carbide layer in the surface of the said embodiment. It is an external appearance perspective view which shows the (a) shaping | molding and provisional baking process in the manufacturing method of the member which formed the metal carbide structure or the metal carbide layer in the surface concerning the said embodiment, and the coating process. It is an external appearance perspective view which shows the mode of injection | throwing in the metal carbide raw material to a blanket in the said manufacturing method, or the raw material which formed the metal carbide layer in the surface. It is a schematic sectional drawing which shows the state after throwing in the metal carbide raw material to a blanket in the said manufacturing method, or the raw material which formed the metal carbide layer on the surface.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, parts that are the same or equivalent to each other are given the same reference numerals in the drawings for the sake of simplicity.

  FIG. 1 is an external perspective view showing a schematic external configuration of a member 10 having a metal carbide structure or a metal carbide layer formed on the surface thereof according to an embodiment of the present invention. This metal carbide structure or member 10 having a metal carbide layer formed on the surface thereof is used as a component part of a SiC crystal growth apparatus by a CVD method.

  Here, the metal carbide structure or the member 10 having a metal carbide layer formed on the surface has a bottomed cylindrical shape with one end opened and the other end closed, and a gas flow passage on the side surface. The member 10 having such a metal carbide structure or a metal carbide layer formed on the surface thereof is used for a reaction vessel of a SiC crystal growth apparatus, a wall surface member of a flow path of an introduced gas, or the like.

  As described above, the SiC crystal growth by this CVD method is performed at a high temperature of about 1600 ° C. to 2500 ° C. in a reducing atmosphere containing a gas containing Si, a gas containing C, and hydrogen in the reaction vessel. The metal carbide structure constituting the reaction vessel and the wall member of the gas flow path to be introduced, or the member 10 having the metal carbide layer formed on the surface thereof has a high melting point.

  Specifically, the member 10 having a metal carbide structure or a metal carbide layer formed on the surface is made of TiC (titanium carbide), TaC (tantalum carbide), NbC (niobium carbide), ZrC (zirconia carbide), VC (vanadium carbide). ) And other metal carbides formed on the whole or part of the member. Any of these metal carbides or metal carbide layers formed on the surface of the member has a high melting point of about 3000 ° C.

  Next, a method for manufacturing the metal carbide structure or the member 10 having a metal carbide layer formed on the surface will be described. FIG. 2 is a view showing a flowchart of the manufacturing process of the metal carbide structure of the present embodiment or the member 10 having a metal carbide layer formed on the surface, and FIG. 3 shows (a) molding and pre-baking process in this manufacturing method. (B) It is an external appearance perspective view which shows a coating | coated process. FIG. 4 is an external perspective view showing a state in which a metal carbide material or a material 11 having a metal carbide layer formed on the surface is put into the blanket 30, and FIG. 5 is a schematic cross-sectional view showing the state after the introduction. It is.

  First, in a shaping | molding and temporary baking process, as FIG.3 (a) shows, the metal carbide powder which comprises the member 10 which formed the metal carbide structure or the metal carbide layer in the surface is prepared, and this metal carbide powder is used. Forming and pre-baking the formed metal carbide powder form the metal carbide material or the material 11 having a metal carbide layer formed on the surface. Here, the metal carbide material 11 is formed into a bottomed cylindrical shape.

  Here, in the formation of the metal carbide material 11, the metal carbide powder is molded into a bottomed cylindrical shape, and then heated in a general oven and temporarily fired, hot press, CIP (Cold Isostatic Press), or the like. What is necessary is just to pre-fire by the general thermoforming method of, and produce a molded object. In the case of a member having a metal carbide layer formed on the surface, for example, the metal carbide layer may be formed on the surface of a bottomed cylindrical member by temporary firing or the like.

  Thereafter, conventionally, a metal carbide material or a metal carbide layer formed on the surface of the metal carbide material or a surface of the metal carbide material 11 formed on the surface surrounded by a blanket 30 made of mullite. 11 is sintered by microwaves to form a metal carbide structure or a member 10 having a metal carbide layer formed on the surface. In this embodiment, a coating step is performed before firing.

  In this coating step, as shown in FIG. 3B, the surface of the metal carbide material or the material 11 having a metal carbide layer formed on the surface is coated with a coating material 20 made of carbon. Here, the covering material 20 is configured to cover the metal carbide material or the material 11 having the metal carbide layer formed on the surface in contact with the outer surface of the metal carbide material or the material 11 having the metal carbide layer formed on the surface. Yes.

  The sheet-shaped covering material 20 is of a thickness that transmits microwaves irradiated during firing, and the main component is carbon, but may contain a small amount of impurities. The carbon constituting the covering material 20 is a substance that easily absorbs microwaves, but in this embodiment, the covering material 20 is formed into a thin sheet so that microwaves can be transmitted.

  Specific examples include carbon sheets such as felt-like carbon and graphoil (trade name of Graphtec). Moreover, in order to permeate | transmit a microwave, the thickness can be about 0.5 mm-1.5 mm, for example. The thickness varies depending on the material of the covering material 20 and the like, but can be easily determined by experiments and calculations.

  Here, the metal carbide material or the material 11 in which the metal carbide layer is formed on the surface has a bottomed cylindrical shape, and the outer surface of the outer periphery and the bottom of the material 11 in which the metal carbide material or the metal carbide layer is formed on the surface by the coating material 20. This is wrapped around the surface, and this is further bound with a carbon string 21 wound around the outer peripheral surface, thereby fixing the covering material 20 to the metal carbide material or the material 11 having a metal carbide layer formed on the surface. Yes.

  In addition, as an attachment method to the metal carbide material of the covering material 20 or the material 11 having a metal carbide layer formed on the surface, for example, by applying a packaging form of an article by a general wrapping paper using folding, for example, A method of fixing without tying with the string 21 is also possible.

  Thus, after covering the surface of the metal carbide material or the material 11 having the metal carbide layer formed on the surface with the coating material 20, as shown in FIG. 4, the metal carbide material or the material 11 having the metal carbide layer formed on the surface is formed. The blanket 30 is put together with the covering material 20. The blanket 30 is made of mullite having a good microwave permeability and a heat insulating effect like a general one, and has a melting point of usually 2000 ° C. or lower.

  Here, the blanket 30 has a bottomed cylindrical shape in which the metal carbide material in the hollow portion or the material 11 having the metal carbide layer formed on the surface and the covering material 20 enter, and in this case, has a bottomed cylindrical shape. The blanket 30 has a lid 31 that closes the opening. The blanket 30 functions as a heat insulating material that keeps the internal metal carbide material or the material 11 having a metal carbide layer formed on the surface thereof at the time of firing.

  Then, the metal carbide material or the material 11 having a metal carbide layer formed on the surface thereof is put into the blanket 30 together with the covering material 20, and then the opening of the blanket 30 is closed by the lid 31. As a result, the metal carbide material or the material 11 having the metal carbide layer formed on the surface and the covering material 20 are located in the blanket 30 hollow portion that is a closed space and are surrounded by the blanket 30.

  Thus, FIG. 5 shows a state in which the metal carbide material or the material 11 having the metal carbide layer formed on the surface and the covering material 20 are surrounded by the blanket 30. That is, in this state, the metal carbide material or the material 11 having a metal carbide layer formed on the surface and the inner surface of the blanket 30 are in contact with each other via the covering material 20.

  Here, the part where the metal carbide material or the material 11 having the metal carbide layer formed on the surface, the covering material 20 and the blanket 30 are contacted is the metal carbide material or the material 11 having the metal carbide layer formed on the surface. The entire outer surface or a part thereof may be used. For example, when the metal carbide material or the material 11 having the metal carbide layer formed on the surface is cylindrical and the blanket 30 is a square tube, the circumferential surface of the metal carbide material or the material 11 having the metal carbide layer formed on the surface is formed. It is only necessary that a part of the blanket 30 is in contact with a part of the inner surface of the four sides via the covering material 20.

  Thus, after the metal carbide material or the material 11 having the metal carbide layer formed on the surface is placed on the blanket 30, the microwave firing process is performed, and the metal carbide material or the material 11 having the metal carbide layer formed on the surface is baked by microwaves. It is set as the member 10 which bonded and formed the metal carbide structure or the metal carbide layer in the surface. At this time, firing is performed in the state shown in FIG. 5, that is, in a state where the metal carbide material or the material 11 having the metal carbide layer formed on the surface is brought into contact with the inner surface of the blanket 30 via the coating material 20.

  Specifically, in the microwave baking process, the blanket 30 is put into a baking chamber in a baking apparatus (not shown). Here, the firing chamber is a non-oxidizing atmosphere.

  In addition, this baking apparatus has a microwave introduction means for introducing microwaves into the baking chamber, as in a general microwave baking apparatus, and the introduced microwave passes through the bracket 30 and the covering material 20. Then, the metal carbide material or the material 11 having a metal carbide layer formed on the surface is irradiated.

  Then, the metal carbide material or the material 11 having the metal carbide layer formed on the surface generates heat by itself, reaches a high temperature of about 1800 to 2000 ° C., and reaches sintering for a time of about 30 minutes to 1 hour, for example. At this time, since the blanket 30 exhibits a heat insulating function and the metal carbide material or the material 11 having the metal carbide layer formed on the surface is kept warm, the metal carbide material or the material 11 having the metal carbide layer formed on the surface is heated. Is sintered and densified to form a member 10 having a metal carbide structure or a metal carbide layer formed on the surface thereof.

  After performing the microwave firing step in this manner, a removal step is performed, and the metal carbide structure formed by sintering or the member 10 having the metal carbide layer formed on the surface is taken out from the blanket 30 together with the covering material 20. About this, the cover 31 of the blanket 30 is opened and the said removal is performed.

  In this embodiment, after that, with the covering material 20 attached, the metal carbide structure or the member 10 having a metal carbide layer formed on the surface is used as a reaction vessel of the SiC crystal apparatus or a wall surface member of the gas flow path to be introduced. The member 10 having the metal carbide layer formed on the metal carbide structure or the surface may be used after removing the coating material 20 from the metal carbide structure or the member 10 having the metal carbide layer formed on the surface. You may use as a wall surface member of a container or the flow path of the gas to introduce. The reason is as follows.

  First, according to the present embodiment, the coating material 20 made of carbon is a thin sheet-like material capable of transmitting microwaves, but has a very high melting point as a characteristic property of carbon. There is almost no chemical reaction with the blank 11 made of mullite or the material 11 having a metal carbide layer formed thereon. Therefore, even after taking out from the blanket 30, the amount of mullite adhering to the surface of the covering material 20 is significantly reduced compared to the conventional case.

  Further, the metal carbide structure or the member 10 having a metal carbide layer formed on the surface thereof is used as a component part of an SiC crystal growth apparatus by a CVD method. This crystal growth is performed by using a gas containing Si as described above. This is performed at a high temperature of about 1500 ° C. to 2500 ° C. in a reducing atmosphere containing a gas containing C and hydrogen.

  And in such a state, since the covering material 20 made of carbon is vaporized and removed as hydrocarbons or the like, it does not become a contaminant to the SiC crystal. On the other hand, since conventional mullite contains Si, Al, and O, it is likely to be mixed into the SiC crystal as a contaminant.

  Therefore, the metal carbide structure or the member 10 on which the metal carbide layer is formed on the surface after being taken out from the blanket 30 may remain in the state where the covering material 20 is attached. In this case, the surface treatment of the metal carbide structure after firing or the member 10 having the metal carbide layer formed on the surface is unnecessary.

  However, if the covering material 20 is peeled off from the metal carbide structure taken out from the blanket 30 or the member 10 having a metal carbide layer formed on the surface, the mullite component of the blanket 30 attached to the covering material 20 is metalized together with the covering material 20. Since it can remove from the carbide | carbonized_material structure or the member 10 which formed the metal carbide layer in the surface, it is preferable.

  Moreover, the covering material 20 can be removed by a simple process of peeling the covering material 20. Even if the covering material 20 remains on the surface of the metal carbide structure or the member 10 having the metal carbide layer formed on the surface without being completely peeled off, it is removed in the atmosphere of crystal growth for the reasons described above. So there is no problem. That is, in this case, the surface processing of the metal carbide structure after firing or the member 10 having the metal carbide layer formed on the surface thereof is greatly simplified as compared with conventional polishing or the like.

  As described above, according to the present embodiment, the metal carbide material or the material 11 having the metal carbide layer formed on the surface thereof is coated with the coating material 20 and fired, thereby suppressing the mullite adhesion amount on the surface of the coating material 20. Moreover, the coating material 20 itself does not become a contaminant during the SiC crystal growth. Therefore, according to the present embodiment, a conventional process such as polishing after sintering is not required, and surface processing of the sintered metal carbide structure or the member 10 having a metal carbide layer formed on the surface is facilitated. can do.

(Other embodiments)
In addition, in the said embodiment, although the member 10 which formed the metal carbide structure or the metal carbide layer on the surface was a bottomed cylindrical thing, the shape is not limited to this, Both ends open. A cylindrical shape, a square tube shape, a stepped tube shape, or the like may be used, and further, a plate shape, a block shape, an indeterminate shape, or the like may be used.

  In any case, the metal carbide structure or the member 10 having the metal carbide layer formed on the surface thereof may have a different shape as appropriate depending on the components of the SiC crystal growth apparatus. And when covering the metal carbide structure which makes such various shapes, or the member 10 which formed the metal carbide layer in the surface, if the above-mentioned thin sheet-like coating material 20 is used, a metal carbide structure or surface The covering material 20 is deformed according to the outer shape of the member 10 on which the metal carbide layer is formed, so that the covering can be easily performed.

DESCRIPTION OF SYMBOLS 10 Metal carbide structure or member in which metal carbide layer is formed on surface 11 Metal carbide material or material in which metal carbide layer is formed on surface 20 Coating material 30 Blanket

Claims (3)

A method for producing a metal carbide structure made of a metal carbide used as a component of a SiC crystal growth apparatus by a CVD method or a member (10) having a metal carbide layer formed on a surface thereof,
In the state where the metal carbide material made of the metal carbide or the material (11) having the metal carbide layer formed on the surface is surrounded by the blanket (30) made of mullite, the metal carbide material or the material having the metal carbide layer formed on the surface ( In the method for producing a metal carbide structure or a member having a metal carbide layer formed on the surface, the metal carbide structure or member (10) having a metal carbide layer formed on the surface by sintering 11) with a microwave,
The surface of the metal carbide material or the material (11) having a metal carbide layer formed on the surface is coated with a coating material (20) made of carbon and having a sheet shape with a thickness that transmits microwaves,
In the state where the metal carbide material or the material (11) on which the metal carbide layer is formed on the surface and the inner surface of the blanket (30) are brought into contact with each other through the covering material (20), the sintering is performed.
Thereafter, the metal carbide structure formed by the sintering or the member (10) having a metal carbide layer formed on the surface is taken out from the blanket (30) together with the covering material (20). The manufacturing method of the member which formed the metal carbide layer in the structure or the surface.   After the metal carbide structure or the member (10) having a metal carbide layer formed on the surface is taken out of the blanket (30) together with the covering material (20), the metal carbide structure is formed on the metal carbide structure or surface. The method for producing a metal carbide structure or a member having a metal carbide layer formed on a surface thereof according to claim 1, wherein the covering material (20) is peeled off and removed from the member (10).   3. The metal carbide structure or the metal carbide layer according to claim 1 or 2, wherein the metal carbide structure or the member (10) having a metal carbide layer formed on the surface has a hollow cylindrical shape. Manufacturing method of formed member.

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