JP2005289744A - Method for manufacturing reaction sintered silicon carbide structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a reaction sintered silicon carbide structure which has excellent structural strength, corrosion resistance, durability, etc., in a wide service temperature range from room temperature up to a high temperature and can easily and efficiently manufacture even the small-sized structure having intricate shapes with high dimensional accuracy. <P>SOLUTION: A raw material mixture prepared by mixing silicon carbide powder, carbon powder and a binder is molded and a plurality of sheet-like moldings 2 with grooves are manufactured and a plurality of the sheet-like moldings 2 are temporarily joined by adhesives, and thereby a laminate internally provided with the grooves 1 in the form of pores 5 is formed. The obtained laminate is subjected to a binder removing treatment to form a degreased body and thereafter the degreased body is heated to impregnate the same with molten silicon and to give rise to reaction sintering, whereby the integral sintered compact is formed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a reaction sintered silicon carbide structure, and in particular, a structure having excellent structural strength, corrosion resistance, durability, etc. in a wide use temperature range from room temperature to high temperature, and having a small and complicated shape. However, the present invention relates to a method for producing a reaction sintered silicon carbide structure that can be produced easily and efficiently.

  Structural parts made of sintered oxide or non-oxide ceramics that are superior in heat resistance, wear resistance, insulation characteristics, chemical resistance, etc. compared to conventional metal parts are tool parts, corrosion resistant parts, automobiles It is widely used in various industrial fields as engine parts for aircraft, ships, etc., gas turbine parts, and chemical plant components.

  For example, chemical production plants that conventionally produce sulfuric acid, nitric acid, etc., various chemical plants that use the same kind of chemical substances, energy plants, environmental hazardous substances treatment equipment, gasification melting furnaces for waste treatment, etc. As a structural component material used in plants operating under conditions, conventional metal materials are insufficient in corrosion resistance at high temperatures, and more thermally and chemically stable ceramic materials are used. Is planned.

  In particular, as a ceramic heat exchanger, a tube-shaped single-ended heat exchanger having a simple structure in which a single hole (heat radiation tube) is formed has been put to practical use for an industrial furnace. For example, a radiant tube (thermal radiation tube) that has been used since about 1994 in a continuous annealing furnace having a furnace temperature of 1150 ° C. is intended to conduct radiant heat transfer by burning a burner from the inside. The radiant tube is used not only for radiating heat of combustion into the furnace but also for recovering and regenerating heat generated from the furnace by blowing low-temperature air into the tube.

  Ceramic heat exchangers as described above often have large structures considering the poor manufacturability of ceramic members, which are mainly hard and brittle and easily damaged during processing. Currently, there is almost no application to compact heat exchangers with high density and complex integration.

  In addition, in order to increase the size and complexity of structural parts that are difficult to manufacture with integrated ceramic members, conventionally, a plurality of ceramic members have been prepared as component units. Attempts have been made to fabricate large and complex structural parts that are joined (see, for example, Patent Document 1).

  Furthermore, as a conventional method for producing a ceramic member, a silicon carbide body (a silicon carbide-based sintered body or a molded body or a calcined body as a precursor thereof) and a porous silicon carbide body (molding in a reactive sintering process of silicon carbide) Body, calcined body, sintered body, etc.) through a bonding layer made of thermosetting resin containing silicon carbide fine powder, and impregnated with molten silicon from the porous silicon carbide body side A method of joining a silicon carbide body and a porous silicon carbide body has also been proposed (see, for example, Patent Document 2).

In the above bonding method, carbon contained in the bonding layer and molten silicon are reacted to form a reaction sintered silicon carbide layer at the bonding portion, and the silicon carbide is formed via the reaction sintered silicon carbide layer. The body and the porous silicon carbide body are joined. In addition, by using this bonding method, for example, a plurality of parts units made of silicon carbide are bonded with a resin-based adhesive containing silicon carbide powder, and after debinding, impregnated with molten silicon. A method of integrally joining the component units is also implemented.
JP 2002-11653 A (page 1-2, FIG. 2) Japanese Examined Patent Publication No. 5-79630 (page 1-4, Fig. 1)

  However, the conventional method for manufacturing a ceramic structure is still a method for manufacturing a large structure, and a manufacturing technique for applying to a compact heat exchanger having a complicated shape is not disclosed. . In particular, there is a problem that it is extremely difficult to finish a structure having a complicated shape by forming a large number of pores for heat exchange in a ceramic sintered body having high hardness and brittleness. Also, simply bonding multiple component units using adhesives will result in low bonding strength, especially in high-temperature operating conditions, the bonding strength and the strength of the structure will tend to decrease, resulting in poor durability and lack of reliability. There was also a point.

  The present invention has been made to solve the above-described conventional problems, and has excellent structural strength, corrosion resistance, durability, etc. in a wide use temperature range from room temperature to high temperature, and has a small and complicated shape. It is an object of the present invention to provide a method for producing a reaction-sintered silicon carbide structure that can be produced easily and efficiently with high dimensional accuracy even if it is a structure.

  In order to achieve the above object, a method for producing a reaction sintered silicon carbide structure according to the present invention comprises forming a raw material mixture formed by mixing silicon carbide (SiC) powder, carbon (C) powder and a binder. A plurality of plate-like molded bodies with grooves were prepared, and a laminate having the above grooves as pores was formed by temporarily joining the plurality of plate-shaped molded bodies with an adhesive, and obtained. The laminated body is subjected to a debinding process to obtain a degreased body, and then the degreased body is heated, impregnated with molten silicon and subjected to reactive sintering to form an integrated sintered body.

  That is, according to the method of the present invention, a plurality of grooved plate-shaped molded bodies are produced from a raw material mixture composed of silicon carbide powder, carbon powder, and a binder, and these plate-shaped molded bodies are bonded together. The reaction-sintered silicon carbide structure in which pores corresponding to the groove shape are formed is easily and efficiently manufactured by bonding with an agent and impregnating with molten silicon after the binder removal treatment. Can do.

  Since silicon carbide (SiC) has a higher thermal conductivity than other ceramic sintered bodies, the sintered body is a structure that requires a particularly high thermal conductivity such as a heat exchanger or a heat dissipation mechanism. It is effective as a constituent material.

  The groove formed in the plate-like molded body is a groove to be a pore formed inside the sintered body, and the other pore-shaped molded body is overlapped on one molded body in which the groove is formed. Is formed. Since the groove is formed on the surface of the plate-shaped molded body, it can be formed into a complicated shape with high definition by processing from the surface side of the molded body, and a fine shape corresponding to the groove shape. The shape of the hole can also be formed with high definition and a complicated shape.

  As the adhesive for temporarily joining the plurality of plate-shaped molded bodies, an organic adhesive in which a carbon source remains by heat treatment, a resin, a silicon carbide powder and / or a resin-based material mixed with carbon powder, or the like is used. preferable.

  The debinding process is an operation of removing a binder (binder) added to the raw material mixture to maintain a predetermined shape of the molded body to obtain a degreased body. Specifically, the laminate (molded body) is not used. This is an operation of heating to a temperature of 600 to 850 ° C. in an air flow of active gas or nitrogen gas and holding for 1 to 3 hours. The heating process for the binder removal treatment and the molten silicon impregnation process described later can be used in the same heating process.

  In the SiC reactive sintering and molten Si impregnation processes, a mixture of SiC fine powder and C powder is molded and then heated at a high temperature of about 1450 to 1500 ° C. to penetrate the molten Si into the molded body. At the same time, reaction sintering proceeds. A part of the infiltrated Si reacts with C in the molded body to generate SiC secondarily, and the rest fills the voids in the molded body to form a dense sintered body. In this sintered body, since the infiltrated Si and the secondary SiC are present in the voids in the molded body, the dimensional change due to the heat treatment is very small, especially for the preparation of complex shapes. This is advantageous.

  In addition, since the amount of Si remaining in the SiC reaction sintered body is about 10 to 20% by mass, the structural strength may suddenly decrease in the operating temperature range above the melting point of Si (1414 ° C.). In the use temperature range up to the melting point, the structural strength almost the same as the normal temperature can be maintained.

  The method for forming the pores is not particularly limited. That is, not only a method of forming from a plurality of grooves formed on the surface of the flat plate-shaped body, but also a method using a core as shown below can be used.

  That is, as a method for producing a reaction sintered silicon carbide structure according to the present invention, a raw material mixture obtained by mixing silicon carbide powder, carbon powder and a binder is not fixed in movement in the pressure axis direction (ie, A molded body having pores corresponding to the core is formed by filling a mold having a core (movable in the axial direction) and press-molding, and the resulting molded body is subjected to binder removal treatment. After carrying out, it may be heated and impregnated with molten silicon and reacted and sintered to form a sintered body.

  According to the manufacturing method, pores corresponding to the shape of the core disposed in the mold can be easily formed in the molded body.

  Further, as a method for producing a reaction sintered silicon carbide structure according to the present invention, a molding die in which a slurry is prepared by adding a solvent and a binder to a raw material mixture composed of silicon carbide powder and carbon powder, and a core is disposed. The above slurry is cast into a molded body having a pore corresponding to the shape of the core by molding by a gel casting method or a slip casting method, and a binder removal treatment is performed on the obtained molded body. After implementation, the degreased body may be heated, impregnated with molten silicon, and subjected to reactive sintering to form a sintered body.

  Here, the gel casting method is a method in which a gel-shaped raw material mixture is filled in a mold and dried to obtain a molded body having a predetermined shape, and the slip casting method is made into a slurry by adding a dispersion medium such as water. In this method, a raw material mixture is poured into a mold and dried to obtain a molded body having a predetermined shape.

  Also in the above manufacturing method, pores corresponding to the shape of the core disposed in the mold can be easily formed in the molded body.

  In addition, as a method for producing a reaction sintered silicon carbide structure according to the present invention, a kneaded product is prepared by adding and kneading a solvent and a binder to a raw material mixture composed of silicon carbide powder and carbon powder. A molded body in which pores corresponding to the shape of the die or core are formed by extrusion molding via a die having a shape or extrusion molding while inserting a wire-like core into a kneaded product. After preparing and removing the binder from this molded body, it is heated and reaction-sintered to form a sintered body. At the same time, this sintered body is impregnated with molten silicon to be densified. May be.

  Also in the above manufacturing method, pores corresponding to the shape of the die or the shape of the core inserted into the kneaded product are formed in the molded body by extrusion molding while inserting the honeycomb-shaped die or the wire-shaped core. It can be formed easily.

  In the method for producing the reaction-sintered silicon carbide structure described above, it is preferable to impregnate molten silicon with boron nitride (BN) attached to the inner surface of the pore. By preliminarily adhering this BN to the inner surface of the pores and impregnating with molten silicon, it is possible to effectively prevent excessive silicon from adhering to the inner surface of the pores and form pores with high dimensional accuracy. Can do.

  That is, the reaction-sintered silicon carbide sintering step is also a process of impregnating a sintered body with molten metal silicon, and a phenomenon that excessive silicon adheres to the surface of the sintered body after sintering often appears. Since this excessive silicon adhesion may occur on the entire surface of the sintered body, there is a concern that problems such as filling the pores formed by the above-described method or reducing the cross-section of the pores may occur. .

  In order to solve such a problem, boron nitride (BN) having poor wettability with respect to molten silicon was partially adhered to at least the inner surface of the groove to be a pore and the back surface of the adjacent plate-shaped molded body. By impregnating with molten silicon in a state, it is possible to effectively suppress the adhesion of excessive silicon to the inner surface of the pores, and it is possible to form pores with good shape accuracy and finished state.

  Moreover, the following manufacturing method can also be employ | adopted using the characteristic of the substance with bad wettability with respect to the above molten silicons.

  That is, in the method for producing a reaction sintered silicon carbide structure according to the present invention, the core is formed of one material selected from boron nitride (BN), BN-coated carbon, and carbon whose surface is densified. In addition, a manufacturing method characterized by impregnating the molded body with molten silicon in a state where the core is placed in a mold can be employed.

  The carbon whose surface is densified means a glassy carbon whose surface roughness is adjusted to 10 μmRa or less, preferably 5 μmRa or less. BN, BN-coated carbon, and carbon whose surface is densified used in the above production method are all substances having poor wettability to molten silicon. Therefore, even when the core made of any of the above materials is placed inside the mold and the sintered body is impregnated with the molten silicon and integrated with the core, excess silicon adheres to the sintered body. Therefore, the dimensional accuracy of the sintered body itself and the pores can be kept high. Further, since the core is less adhered to the impregnated silicon, the core can be easily taken out and separated from the sintered body.

  Furthermore, in the method for producing a reaction-sintered silicon carbide structure of the present invention, after producing the molded body, one type selected from boron nitride (BN), BN-coated carbon, and carbon whose surface is densified. A manufacturing method in which pores corresponding to the shape of the core are formed by impregnating the molded body with molten silicon in a state where the core made of the material is inserted into the molded body.

  That is, by preparing a molded body in advance and then inserting a core made of one material selected from the above-mentioned BN, BN-coated carbon, and carbon whose surface is densified, and then impregnating with molten silicon As described above, the effect of preventing the excessive silicon from adhering to the sintered body can be obtained. In particular, in addition to the conventional method of using a core made of a material, by using these methods to suppress excessive silicon adhering to the surface, pores with excellent dimensional accuracy corresponding to the shape of the core can be obtained. It becomes possible to efficiently produce the reaction sintered silicon carbide structure formed inside.

  Further, in the method for producing a reaction sintered silicon carbide structure according to the present invention, the body part of the grooved plate-like molded body is formed by a die press method, an extrusion molding method, a casting molding method, an injection molding method, a doctor blade molding method. On the other hand, it is also possible to employ a manufacturing method in which the groove portion of the plate-shaped molded body is formed by a direct shape imparting process by stamping or a raw processing process.

  That is, as a method for producing a grooved molded body, any one of a dry / wet die press method, an extrusion molding method, a casting molding method, an injection molding method, and a doctor blade molding method can be used. By combining the direct shape imparting process or the raw processing process with the above, it is possible to efficiently produce a reaction sintered silicon carbide structure in which pores having a predetermined high dimensional accuracy are formed.

  Furthermore, in the method for producing a reaction-sintered silicon carbide structure according to the present invention, the inner surface of the pores after the reaction sintering is subjected to sand blasting or water blasting so that the inner surface of the pores can be obtained with high dimensional accuracy. It becomes possible to finish.

  That is, in the reaction-sintered silicon carbide sintering step and the step of impregnating the molten metal silicon into the sintered body, in some cases, a phenomenon occurs in which excessive silicon adheres to the surface of the sintered body after sintering, In particular, on the inner surface of the pore, there is a possibility that a portion where excessive silicon adhesion cannot be completely prevented remains. For these parts, sandblasting or water blasting is applied to the inner surface of the pore as the final finishing method, so that excess silicon adhering to the surface of the sintered body and the inner surface of the pore is quickly and easily removed. Therefore, it is possible to greatly improve the finishing accuracy of the structure.

  The reaction-sintered silicon carbide structure according to the present invention is characterized by comprising a reaction-sintered silicon carbide sintered body having pores manufactured according to the above-described manufacturing method.

  According to the method for producing a reaction sintered silicon carbide structure according to the present invention, a groove is formed at the stage of a soft molded body to assemble a basic structure of fine pores, or a core is used to In addition, it is possible to easily and quickly manufacture a structure having complex-shaped pores, and in particular, the pores can be used as heat radiation tubes and heat medium flow paths. A compact device such as a compact heat exchanger can be realized.

  In addition, since the compact with fine pores inside is degreased and impregnated with molten silicon and reactively sintered to form a sintered body, the entire sintered body can be densely formed and pores can be formed. Therefore, it is possible to form densely joined portions of a plurality of stacked plate-like molded bodies, and to obtain a highly reliable structure that is free from peeling and cracking.

  Next, examples of the method for manufacturing a silicon carbide structure according to the present invention will be described below together with comparative examples, in particular, examples in which pores are formed and the main body of the structure is formed by reactive sintering of silicon carbide. FIG. 1 is a production flow diagram briefly showing the flow of a process for producing pores and producing a structure by reactive sintering in accordance with the method for producing a silicon carbide structure according to the present invention.

[Example 1]
A molding binder was added to a raw material mixture composed of silicon carbide (SiC) powder and carbon (C) powder to produce a granulated powder having an average particle size of 150 μm. Next, the obtained granulated powder was filled in a mold and press-molded to produce a large number of flat molded bodies having a length of 100 mm × width of 100 mm × thickness of 6 mm. Next, using a vertical milling grinder equipped with a carbide drill having a diameter of 2 mm, grooves 1 having a rectangular cross-sectional shape having a width of 3 mm and a depth of 3 mm are formed in one direction on the surface of each flat plate-shaped molded body. By doing so, a grooved flat plate-like molded body 2 as shown in FIG. 2 was prepared. The pitch of the grooves 1 was 6 mm, and the wall thickness of the molded body formed between the grooves 1 and 1 was 3 mm.

  Next, as shown in FIG. 2, ten of the flat plate-like molded bodies 2 were laminated, and an organic adhesive was applied to the contact surfaces of the flat plate-like molded bodies 2 to temporarily bond them to form a laminated body 3. A flat plate-like molded body 4 having no grooves is joined to the top of the laminate 3. The application amount of the organic adhesive was adjusted so that the thickness of each bonding layer was 200 to 300 μm or less. A large number of pores 5 surrounded by the back surfaces of the plate-like molded bodies 2 and 4 adjacent to the groove 1 formed in the grooved plate-like molded body 2 are formed in the laminated body 3.

  Next, the binder removal process was implemented with respect to the laminated body 3 prepared as mentioned above. This debinding treatment is carried out by heating the laminate 3 in a nitrogen gas stream, raising the temperature to 800 ° C. and holding for 2 hours, and carbonizing or removing the binder contained in the molded body to remove the degreased body. It was.

  Thereafter, the obtained degreased body was impregnated with molten silicon and integrated to prepare a reaction sintered silicon carbide structure 6 having a large number of pores 5 as shown in FIG. Here, the molten silicon impregnation operation was performed by heating and holding in a vacuum at a temperature of 1450 ° C. for 1 hour in a state where silicon metal was placed in contact with the laminate (joined molded body) 3.

  However, in the reaction-sintered silicon carbide structure 6 impregnated with the above-described molten silicon, excess silicon was found to adhere to the inner surface of the pores 5 and a part of the outer periphery of the structure. Carried out. As a result, a reaction sintered silicon carbide structure 6 in which pores 5 having good dimensional accuracy and a smooth inner surface were formed was obtained.

[Example 2]
A solvent and a binder for solidification molding (for gel casting) were added to a mixed powder composed of silicon carbide powder and carbon powder and mixed uniformly to prepare a slurry (slurry). Next, as shown in FIG. 3, the slurry was poured into a molding die in which cores 7 for forming pores were previously arranged, and a molded body gelled by the reaction of a solidifying molding binder was obtained. The cross-sectional dimension of the core 7 corresponding to the pores was 3 mm wide × 3 mm deep, and the overall size of the compact was 105 mm long × 105 mm wide × 65 mm high.

  Next, after the molded body prepared as described above was gradually dried in a drying chamber, a binder removal treatment was performed. This debinding treatment was carried out by heating the molded body in a nitrogen gas stream, raising the temperature to 800 ° C., and holding for 2 hours.

  Next, the molded body subjected to the debinding process was impregnated with molten silicon and integrated. The molten silicon impregnation operation was performed by heating to a temperature of 1450 ° C. in a vacuum and holding for 1 hour in a state where silicon metal was placed in contact with the compact.

  In addition, when the inner surface of the pore 5 obtained by removing the core 7 and the outer surface of the structure were observed, adhesion of excess silicon was observed on the inner surface of the pore 5 and a part of the outer periphery of the structure. A finishing process was performed by sandblasting on the adhered part. As a result, a reaction sintered silicon carbide structure 6a in which pores 5 having good dimensional accuracy and a smooth inner surface were formed was obtained.

[Example 3]
By processing the raw material mixture in the same manner as in Example 1 and further performing groove processing, a large number of grooved flat plate-like molded bodies 2 having the same dimensions as in Example 1 were produced. Before laminating these flat plate-like molded bodies 2 with grooves, BN powder is attached only by a spray coating method using a mask on the portion that forms the pore inner surface when assembled, as shown in FIG. A BN coating layer 8 was formed on the inner surface of the groove 1.

  Next, ten grooved flat plate-like molded bodies 2 in which the BN coating layer 8 is formed on the inner surface of the groove 1 as described above are sequentially laminated, and an organic adhesive is applied to the contact surfaces of the molded bodies 2. The laminated body was temporarily joined. The application amount of the organic adhesive was adjusted so that the thickness of each bonding layer was 200 to 300 μm or less.

  Next, a binder removal treatment was performed on this laminate. This debinding treatment was carried out by heating the laminate in a nitrogen gas stream, raising the temperature to 800 ° C., and holding for 2 hours.

  Thereafter, the laminated body subjected to the binder removal treatment was impregnated with molten silicon and integrated. This molten silicon impregnation operation was carried out by placing silicon metal in contact with the laminate (joined molded body), heating to 1450 ° C. in vacuum, and holding for 1 hour. As a result, a reaction sintered SiC structure having a large number of fine pores formed therein was obtained as in Example 1.

  In addition, when the inner surface and the outer surface of the pores of the obtained structure were observed, no large excess silicon adhered to the inside of the pores, and no finishing process was required or only a very simple finishing process was required. It was possible to completely remove the adhering portion by partially performing the above. In addition, since excess silicon was found to adhere to a part of the outer peripheral surface of the structure, finishing processing was performed by sandblasting. According to this example method, a reaction sintered silicon carbide structure in which pores having good dimensional accuracy and a smooth inner surface were formed was efficiently obtained.

[Example 4]
A raw material mixture (slurry for gel casting) was prepared in the same manner as in Example 2 except that a rod made of a BN sintered body was placed inside the mold as a core, and the slurry was poured into the mold and reacted to form a gel. As a result, a molded body having the same dimensions as in Example 2 was obtained. A rod made of a BN sintered body is inserted into all the pores of the molded body, and the clearance between the rod (core) made of the BN sintered body and the pores is 0.3 mm or less on average. .

  Next, the molded body was degreased in a state in which a rod made of a BN sintered body was inserted, and then impregnated with molten silicon as it was and integrated densely. In addition, the said binder removal process was implemented by heating and heating up a molded object to the temperature of 800 degreeC in nitrogen gas stream, and hold | maintaining for 2 hours. Further, the molten silicon impregnation operation was performed by heating to 1450 ° C. in a vacuum and holding for 1 hour in a state where silicon metal was placed in contact with the molded body. After sintering, adhesion between the BN sintered body rod as the core and the molten silicon was not observed at all, and each core could be easily collapsed and removed by simple blasting. By removing the BN sintered body rod as the core, a reaction sintered SiC structure in which pores were formed in the trace of the core was obtained.

  When the pores and outer surface of the obtained structure were observed, no large excess silicon adhered to the inside of each pore and the finishing process was almost unnecessary. Only processing was partially performed. In addition, since excess silicon was found to adhere to a part of the outer peripheral surface of the structure, finishing processing was performed by sandblasting. According to this example method, a reaction sintered silicon carbide structure in which pores having good dimensional accuracy and a smooth inner surface were formed was efficiently obtained.

[Example 5]
A kneaded product was prepared by adding and kneading a solvent and a binder to a raw material mixture composed of silicon carbide powder and carbon powder. Next, this kneaded product was processed under the same conditions as in Example 2 including the dimensions of the structure, except that the pores were formed by extrusion molding through a honeycomb-shaped die. A reaction sintered SiC structure having pores formed therein was manufactured.

  However, since excess silicon was found to adhere to a part of the inner surface and the outer peripheral surface of the pores of the structure according to Example 5, finishing processing was performed on the adhesion portion by sandblasting. As a result, a reaction sintered silicon carbide structure in which pores having good dimensional accuracy and a smooth inner surface were formed was efficiently obtained.

[Example 6]
In the manufacturing method of Example 5, after inserting a rod made of a BN sintered body at a position corresponding to the pores of the molded body, a degreasing treatment (debinding treatment) and an impregnation operation with molten silicon were performed, By treating in the same manner as in Example 5, a reaction sintered silicon carbide structure according to Example 6 having a large number of pores formed therein was produced.

  When the inside and outside surfaces of the pores of this reaction sintered SiC structure were observed, no large excess silicon was found to adhere to the inside of each pore, and finishing was almost unnecessary. In addition, only a simple finishing process was partially performed on a very small part. On the other hand, since excess silicon was found to adhere to a part of the outer surface of the structure, finishing processing by sandblasting was performed on the attached portion. By this example method, a reaction sintered silicon carbide structure in which pores having good dimensional accuracy and a smooth inner surface were formed was efficiently obtained.

[Comparative Example 1]
As a manufacturing method compared with Example 1, after forming a granulated powder by adding a molding binder to a raw material mixture composed of silicon carbide powder and carbon powder, the granulated powder was subjected to cold isostatic pressing (CIP). ) To form a block-shaped molded body having a length of 100 mm × width of 100 mm × thickness of 60 mm. Using a vertical milling machine equipped with a carbide drill having a diameter of 1 to 2 mm, pores having a cross-sectional shape of 3 mm in length and 3 mm in width were formed in one direction in the block-shaped molded body. The pitch between the grooves was set to 6 mm.

  However, when the length of each pore is about 30 mm or more, it becomes difficult to form a partition wall having a thickness of 3 mm that separates adjacent pores, and processing is impossible. That is, in the manufacturing method according to Comparative Example 1 using the normal CIP green forming method to the fine pore processing process, it is not possible to produce a structure having high-density pores having long dimensions as described above. It turned out to be possible.

  On the other hand, in the reaction-sintered silicon carbide structure according to the present example, the thickness of the pores is particularly 30 mm or more and the thickness of the sintered body between adjacent pores is 3 mm or less. It becomes possible to realize a structure having a fine pore structure for the first time.

[Comparative Example 2]
As a means for improving the manufacturing method according to Comparative Example 1, the block-shaped molded body formed by CIP is calcined at a temperature of 1800 ° C. in an inert atmosphere, and similarly processed in the state of a calcined body with increased structural strength. Tried. However, this calcined body was higher in strength than the molded body, but almost no toughness based on stickiness like the molded body appeared, and was easily damaged by the impact force acting during drilling work with a drill, There was a problem of generating cracks, and no significant improvement in workability was observed.

[Comparative Example 3]
Other than the point that the rod made of carbon whose surface is not densified and whose surface roughness is 20 μm-Ra is placed inside the mold as a core, and the carbon rod is inserted as a core into all the pores of the molded body The reaction sintered carbonization according to Comparative Example 3 is carried out by pouring the raw material slurry into the mold under the same conditions as in Example 2, gelling and molding, and further performing the binder removal treatment and the impregnation operation with molten silicon. A silicon structure was prepared.

  However, in the structure of Comparative Example 3, as a result of the remarkable reaction between the carbon rod as the core and the molten silicon after the reaction sintering, it was confirmed that the core was firmly bonded to each other, and the core was removed. It was difficult to form pores.

  As is clear from the comparison of the reaction-sintered silicon carbide structures according to the above examples and comparative examples, according to the manufacturing method according to each example, the grooves 1 are formed at the stage of the soft molded body and the fine structure is obtained. Since the basic structure of the pore 5 is assembled or the fine pore 5 is formed inside the molded body using the core 7, the structures 6 and 6 a having the complex-shaped pore 5 are formed. It becomes possible to manufacture easily and quickly, and in particular, it is possible to realize a small device such as a compact heat exchanger having the pores 5 as heat radiation tubes or heat medium passages.

  Further, since the molded body having fine pores 5 formed therein is reacted and sintered and simultaneously impregnated with molten silicon, the entire sintered body can be formed densely and the pores 5 can be formed. Further, the joined portions of the plurality of plate-like molded bodies 2 stacked on each other can be densely formed, and it is possible to obtain the structures 6 and 6a having excellent reliability with no peeling or cracking.

The process flow figure which illustrated the flow of the process which forms a pore according to the manufacturing method of the silicon carbide structure concerning the present invention, and manufactures a structure by reaction sintering. The perspective view which shows the procedure which laminates | stacks the flat plate-shaped molded object with a groove | channel, and manufactures the structure which has a pore. The perspective view which shows the state which forms a pore by filling the raw material mixture in the shaping | molding die which has arrange | positioned the several core. The perspective view which shows the state which formed the BN application layer in the inner surface of the groove | channel of a flat plate-shaped molded object with a groove | channel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Groove | channel 2 Flat plate-shaped molded object 3 Laminated body 4 Flat-shaped molded body 5 without a groove | channel Porous 6, 6a Reaction sintered silicon carbide (SiC) structure 7 Core 8 Boron nitride (BN) coating layer

Claims (10)

Forming a raw material mixture formed by mixing silicon carbide powder, carbon powder, and a binder to produce a plurality of grooved plate-shaped molded products, and temporarily bonding the plurality of plate-shaped molded products with an adhesive After forming a laminated body with the above grooves as pores and carrying out a debinding process on the obtained laminated body to obtain a degreased body, the degreased body is heated and impregnated with molten silicon to react. A method for producing a reaction-sintered silicon carbide structure, characterized by sintering to form an integral sintered body. Corresponding to the above-mentioned core by filling the raw material mixture made by mixing silicon carbide powder, carbon powder and binder into a mold with a core that is not fixed in the direction of the pressure axis. After forming a molded body having pores to be formed and performing a binder removal treatment on the obtained molded body, the degreased body is heated, impregnated with molten silicon, and subjected to reactive sintering to form an integrated sintered body and A process for producing a reaction-sintered silicon carbide structure characterized in that: A slurry is prepared by adding a solvent and a binder to a raw material mixture composed of silicon carbide powder and carbon powder, and the slurry is cast into a mold having a core disposed therein, and then molded by gel casting method or slip casting method. After forming a molded body having pores corresponding to the shape of the core inside, and performing a binder removal treatment on the obtained molded body, it is heated and impregnated with molten silicon and subjected to reactive sintering. A method for producing a reaction-sintered silicon carbide structure, characterized by comprising an integral sintered body. A kneaded product is prepared by adding a solvent and a binder to a raw material mixture composed of silicon carbide powder and carbon powder, and extruding the kneaded product through a honeycomb-shaped die, or forming a kneaded product in a wire shape. By extruding while inserting the core, a molded body in which pores corresponding to the shape of the die or core are formed is prepared, and after the binder is removed from the molded body, A method for producing a reaction sintered silicon carbide structure, characterized in that a degreased body is heated, impregnated with molten silicon and subjected to reaction sintering to form an integrated sintered body. The method for producing a reaction sintered silicon carbide structure according to any one of claims 1 to 4, wherein the molten silicon is impregnated with boron nitride (BN) attached to the inner surface of the pore. A method for producing a reaction sintered silicon carbide structure. 5. The method for producing a reaction sintered silicon carbide structure according to claim 2, wherein the core is selected from boron nitride (BN), BN-coated carbon, and carbon whose surface is densified. A process for producing a reaction-sintered silicon carbide structure, characterized in that it is formed of one kind of material, the binder is removed from the molded body in a state where the core is disposed, and the molten silicon is subsequently impregnated. . 5. The method for producing a reaction sintered silicon carbide structure according to claim 2, wherein after forming the molded body, boron nitride (BN), BN-coated carbon, and carbon whose surface is densified. A reaction-sintered silicon carbide structure characterized in that a core made of one selected material is inserted into the molded body, and the molded body is debindered and subsequently impregnated with molten silicon. Body manufacturing method. 2. The method for producing a reaction sintered silicon carbide structure according to claim 1, wherein the body portion of the grooved plate-like molded body is formed by a die press method, an extrusion molding method, a casting molding method, an injection molding method, a doctor blade molding method. A method for producing a reaction-sintered silicon carbide structure, which is formed using any of the forming methods, and wherein the groove portion of the plate-shaped formed body is formed by a direct shape imparting process or a raw processing process by embossing. The method for producing a reaction-sintered silicon carbide structure according to any one of claims 1 to 8, wherein the inner surface of the pores after the reaction sintering is subjected to a sand blasting treatment or a water blasting treatment. A process for producing a reaction-sintered silicon carbide structure, characterized in that: A reaction-sintered silicon carbide structure produced by the method for producing a reaction-sintered silicon carbide structure according to claim 1.

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