JP4932042B1 - Surface modification method for sintered carbon and electromagnetic induction heating cooker - Google Patents

Abstract

An object of the present invention is to form a molding material, which is a composite with an uncured phenol resin containing a high concentration of graphite grains, and to form the molded product formed by heating and pressure molding in a mold in an oxygen-free high temperature atmosphere. In a carbon aggregate molded product that enables dielectric heating, distortion remains in the molded product due to excessive discharge pressure in the vicinity of the gate and sudden change in the flow path. As a result, fine cracks were generated in the resin portion in the firing stage, and the resistance due to impact stress such as falling balls was significantly reduced.
A method for modifying the surface of a carbon sintered body according to the present invention includes a silicon compound in a gate-corresponding portion at the center of the bottom surface of a pan-like molded product of a carbon aggregate using graphite-derived carbon as a binder for graphite grains. After the impregnation, a step of heat treatment at 1100 to 1500 ° C. in an oxygen-free atmosphere is included.
[Selection] Figure 3

Description

  The present invention is a carbon sintered body whose strength is improved by providing silicon carbide derived from a silicon compound in a part of a molded product made of a carbon aggregate obtained by firing graphite particles and a phenol resin in an oxygen-free atmosphere. The present invention relates to a surface modification method. The present invention also relates to an electromagnetic induction heating cooker (hereinafter simply referred to as a cooker) which is a pot of a rice cooker by electromagnetic induction heating.

  Stoves and rice cookers that are cooking utensils applying electromagnetic induction heating use electromagnetic induction heating in which iron or stainless steel, which is a magnetic metal, generates heat due to eddy current generated by an induction heating coil that is a high-frequency magnetic field generator. Thus, it has a feature that rapid and uniform heating can be obtained.

  In the cooker, a clad material laminated with aluminum or copper was used as a pan-shaped molded product. However, the clad material is difficult to be shaped into a pan or a pot, and the surface is heat resistant resin such as fluororesin. There were also problems such as peeling of each laminated interface on the painted surface.

  For this reason, it has been proposed to use a carbon condensate having moderate conductivity, dielectric properties and excellent thermal conductivity as a material for an electromagnetic induction heating cooker that replaces conventional iron and stainless steel. (For example, refer to Patent Document 1).

  Further, a cut product of a compressed body pressed into a rod-pillar shape has been introduced (see, for example, Patent Document 2).

  According to the above-described method of manufacturing a cooking utensil, a carbon pillar such as coke is molded into a rod-column shape by a mixture mainly composed of a binder that is a high carbon content such as phenol or pitch, and this is formed in an oxygen-free atmosphere. After obtaining a graphitized carbon aggregate obtained by heating at 1000 to 3000 ° C., it is cut into an arbitrary shape.

  However, the means for obtaining an arbitrary shape by cutting a carbon sintered body has a problem that the material in the hollow portion of the container that occupies most of the cutting is discarded, and the number of processing steps is large.

  In addition, it is difficult to detect defects existing in the carbon compression body in advance, and the characteristics such as design and strength are adversely affected by the exposure of the defects by cutting.

  As a means for solving these problems, the molded product obtained after molding by injecting a mixture of graphite particles and a binder material such as a phenol resin raw material liquid or tar pitch into a mold and pressurizing it, is used. Means for obtaining a carbon aggregate formed into a pan shape by firing is disclosed (for example, see Patent Document 3).

  According to the above-mentioned Patent Document 3, in order to obtain a high flow state in the mold, a raw material in which graphite particles and a binder are mixed needs to contain a large amount of a phenol resin or the like that melts under injection temperature conditions as a binder. . On the other hand, as a cooking utensil capable of electromagnetic induction heating, it is necessary to have a high mixing ratio of graphite particles in order to obtain a carbon aggregate molded product having excellent strength, electrical conduction and thermal conduction. However, a raw material with a low phenolic resin content and a high mixing ratio of graphite grains improves the viscosity and lowers the fluidity, and the surface of the graphite grains does not wet sufficiently so that they aggregate and flow. To lose.

  In addition, by reducing the phenol resin as a binder as described above and mixing a large amount of graphite particles, a defect site where the binder is not applied is generated on the surface of the graphite particles, and the strength of the aggregate is reduced. However, with the decrease in fluidity, there is a problem that many pores remain without being densely packed and the thermal conductivity is lowered.

  In response to the above problem, graphite particles are stirred and dispersed in water in the presence of a surfactant in a reaction stage where both compounds containing a phenol group and an aldehyde group are polymerized to obtain an uncured phenol resin. Thus, there has been proposed a granular composite forming raw material in which the surface of graphite particles is completely covered with a coating film of an uncured portion and spheroidized with the polymerization of a phenol resin. The molding raw material is shaped by curing in pressure heating molding, and the obtained molded product is carbonized with a phenol resin by baking treatment in an oxygen-free high-temperature atmosphere, so that a coagulated body in which the above-described problems are solved can be obtained ( For example, see Patent Document 4).

JP-A-9-75211 JP-A-9-70352 JP 2007-04257 A JP 2010-059372 A

  However, in the injection molding or transfer molding for shaping the molding material with phenol resin complexed on the graphite grain surface into an arbitrary shape, the center of the bottom surface is secured to ensure stable molding of the pan-shaped molded product. It is optimal to provide a gate position in However, on the other hand, it was necessary to accept that the molding material discharged into the mold suddenly changed the flow direction while colliding with the wall surface facing the gate.

  In this case, in the vicinity of the portion corresponding to the gate of the obtained molded product, since the filling of the mold is completed after the graphite particles collide violently, strain remains in the contact portion between the graphite grains, and this is the case when the high temperature in the firing stage. There exists a subject of making it easy to generate | occur | produce a fine crack by releasing distortion.

  The present invention has been made to solve the above-described problems, and provides a surface modification method for a carbon sintered body and an electromagnetic induction heating cooker that improve the strength of the carbon aggregate.

  In the method for modifying the surface of a carbon sintered body according to the present invention, a silicon compound is impregnated in a gate-corresponding portion in the center of the bottom surface of a pan-like molded product of a carbon aggregate using carbon derived from phenol as a binder for graphite grains. Then, it includes a step of performing heat treatment at 1100 to 1500 ° C. in an oxygen-free atmosphere.

  In the method for modifying the surface of a carbon sintered body according to the present invention, a silicon compound is impregnated in a gate-corresponding portion in the center of the bottom surface of a pan-like molded product of a carbon aggregate using carbon derived from phenol as a binder for graphite grains. After that, since it includes a step of performing heat treatment at 1100 to 1500 ° C. in an oxygen-free atmosphere, it obtains a reinforcing effect by silicon carbide (SiC) and secures properties that are unlikely to cause breakage due to collision of other articles. I was able to.

In the figure shown for comparison, resin adhesion of a mixture obtained by pressure-kneading a carbon powder and a phenol resin uncured material obtained by crushing a lump only by kneading with a general molding raw material with an extruder or the like Conceptual diagram. The figure which shows Embodiment 1 and is the conceptual diagram of the shaping | molding raw material which complexed the phenol resin uncured material on the surface. The figure which shows Embodiment 1, and is a figure which shows the comparison result about Examples 1 and 2 and Comparative Examples 1-4 about the falling ball strength (destruction height) in the bottom face center part which is a modification | reformation part.

Embodiment 1 FIG.
<Overview>
Carbon agglomerates used in cooking utensils capable of dielectric heating are formed by molding a molding material that is a composite with an uncured phenol resin containing a high concentration of graphite grains by heating and pressure molding in the mold. The product was fired in an oxygen-free high-temperature atmosphere to secure a molded product that can be heated as a carbon aggregate. Thereafter, if necessary, a fluororesin coating film is formed for the purpose of coating treatment and prevention of adhesion of cooking utensils using an anchor effect impregnated in many pores provided on the surface.

  During molding, when the molding material is discharged into a mold perpendicular to the bottom surface, the excessive discharge pressure in the vicinity of the gate and the graphite powder filling state due to a sudden change in the flow path, for example, the part where the graphite particles are in contact with each other is distorted. Remains in the molded product. As a result, even after shaping due to curing due to heating in the firing stage, fine cracks are generated in the resin portion immediately after demolding in a state where the rigidity of the resin is low and exceeds the Tg (glass transition temperature). The deformation caused by the deformation of the graphite grains due to the deformation is released.

  The fine cracks generated here greatly reduce the impact strength of the part of the carbon aggregate subjected to the firing treatment performed in an oxygen-free atmosphere at 900 ° C. or higher, and the stress applied to the cooking aids. Since the resistance of the material is reduced and impact damage is likely to occur, it is necessary to reinforce a limited portion near the gate.

  In this embodiment, the graphite aggregate molded product is fired in an oxygen-free atmosphere after coating and impregnation with an organosilicon compound in a region in the vicinity of the gate where excessive distortion tends to remain inside. A silicon carbide (SiC) provided is obtained to reinforce an occurrence portion such as a crack and obtain an aspect in which impact destruction is not easily caused.

<Means>
After injecting molding material consisting of graphite grains and phenolic resin into the mold, the molding material is heated and pressed to cure and molded, and then obtained by performing a first firing treatment at an oxygen-free high temperature. The carbon aggregates were modified by applying a silane compound in the vicinity of the gate equivalent and impregnating the carbon aggregates, and then performing a second baking process again at a high temperature in an oxygen-free state.

<Action>
A molded product obtained by heat and pressure molding is subjected to a first firing process in which a firing temperature of 800 ° C. or less is taken out as an aggregate in which the binder phenol resin is amorphous carbon. A carbon aggregate to be used for the cooking utensil according to the present embodiment was obtained by performing a second baking process at 1200 ° C. or higher in a state of impregnating with.

The silicon compound used here is silazane or polysilazane. The former is hydrolyzed by weakly acidic water and converted into SiO ₂ , and the latter reacts with moisture in the atmosphere and is converted into silica glass.

In general, a silazane compound is a silanol produced by hydrolysis of a silane coupling agent which is an organosilicon compound having both an organic functional group and a hydrolyzable group (OR) in addition to water (H ₂ O) adsorbed on the substrate surface. It reacts with the group (Si-OH) and is retained without scattering even at high temperatures, decomposes in the second firing step, and reacts with amorphous carbon containing impurities with slightly remaining active groups. Thus, silicon carbide (SiC) having an excellent strength is obtained, and the cracked portion is reinforced to obtain a mode in which impact destruction is unlikely to occur.

<Effect (Inventive step)>
The silicon compound impregnated in the vicinity of the gate of the excessive strain residue and fine cracks by the cookware made of the carbon aggregate is silicon carbide (reaction product with amorphous carbon at a firing temperature of 1200 ° C. or higher) The reinforcing effect by silicon carbide (SiC) was obtained, and it was possible to secure a property that is less likely to break due to the collision of other articles.

Silazane will be described. Silazane containing silicon (Si) and nitrogen as constituent components is converted into SiO ₂ when an oxidation reaction is caused. Usually, it is converted into an oxide film by a hydrolysis reaction, but in order to ensure high insulation, it is necessary to avoid that moisture is taken into the SiO ₂ thin film to be produced. For this reason, in the technology developed this time, it was decided to convert to an oxide by reacting ozone without using a hydrolysis reaction in an environment excluding moisture. In the method for producing the SiO ₂ thin film, first, silazane as a raw material was dissolved in a solvent and applied to form a thin film.

Thereafter, a silazane thin films prepared by reacting with ozone, to obtain a SiO ₂ thin film. At this time, the condition of the thin film, the conditions of the reaction with ozone, the reaction environment, etc. are appropriately controlled, and if a stepwise heating process is applied, the quality of the oxide film is improved, and the TFT (Thin Film Transistor, A high-quality SiO ₂ insulating film that can withstand use as a gate insulating layer of a thin film transistor is obtained.

  The characteristics of polysilazane will be described. Polysilazanes include oligomeric and polymeric silazanes, ie, compounds having two or more monomeric silazane units and react with compounds having active hydrogen such as water and alcohols.

Polysilazane and its derivatives include silicon nitride (Si ₃ N ₄ ), silicon carbide (SiC), Si ₃ N ₄ / SiC alloy, Si ₃ N ₄ / carbon alloy, Si ₃ N ₄ / boron nitride alloy, and mixtures thereof It is particularly useful for the preparation of These ceramic materials can be used as building materials, protective coatings, and electronic materials because of their hardness, strength, structural stability, and a wide range of electrical properties under extreme environmental conditions. In particular, these materials can be formed into ceramic fibers useful as composite reinforcements.

The silazane compound reacts and bonds with water (H ₂ O) adsorbed on the surface of the air or the substrate or silanol groups (Si—OH) on the surface, but the silicon dioxide-containing coating used in this embodiment has a silanol on the surface. Since there are many groups, the bond density between the silicon dioxide-containing film and the water-repellent layer made of an organic silazane compound is increased.

  A silane coupling agent is an organosilicon compound having both an organic functional group “Y” that can be expected to react and interact with an organic substance in one molecule and a hydrolyzable group “OR”.

  The composition of polysilazane is a complete inorganic polymer composed only of Si—H, N—H, and Si—N bonds.

  The molecular weight and number average molecular weight Mn of polysilazane are substantially oligomers of about 500 to 2500, and the properties of the resin component excluding the solvent are viscous liquids.

  The solvent of polysilazane will be described. Polysilazane reacts with a substance having OH (hydroxyl group) and hydrolyzes, and at the same time, hydrogen, ammonia, and a silane-based gas are generated. Therefore, polysilazane cannot be brought into contact with water or alcohol. Solvents that dissolve water, such as ketones and esters, are also not preferred. Therefore, xylene, mineral terpenes, high-boiling aromatic solvents, etc. are mainly used from the viewpoint of solubility, stability, and coating film properties.

The yield of polysilazane will be described. In the conversion from a polysilazane thin film to a silica thin film, the following reaction with moisture in the atmosphere is considered to be dominant.
_{- (SiH 2 NH) - +} 2H 2 O → SiO 2 + NH 3 + 2H 2
M = 45 → M = 60
The weight yield associated with this reaction is 60/45 = 133%, and the actually measured value is also extremely high. The reason for this is that not only there is no separation of organic components other than hydrogen, but also an efficient reaction occurs in which 2 mol of oxygen is replaced with 1 mol of nitrogen.

  The low temperature curing (silica conversion) type polysilazane includes an inorganic catalyst-added polysilazane (L110) and an organic catalyst-added polysilazane (P110).

  The inorganic catalyst-added polysilazane (L110) can reduce the conversion temperature to silica, in other words, the temperature of ceramization to about 250 ° C. by adding a Pd compound that is a dehydrogenation and oxidation catalyst.

  The organic catalyst-added polysilazane (P110) can be converted to silica at room temperature by adding an amine-based catalyst that promotes the reaction with water.

  Perhydropolysilazane (PHPS) reacts with moisture in the atmosphere and is converted to silica glass. Consists of perhydropolysilazane as the main component, organic solvent and a small amount of catalyst (room temperature / low temperature baking type), ammonium chloride is a catalyst for the crosslinking of simple oligodimethylsilazane, silane coupling agent is silanol by hydrolysis After producing (Si-OH), silanols condense together to form a silane oligomer having a siloxane bond (Si-O-Si) to enhance the properties of silicone, but on the other hand, the number of silanol groups is reduced to reduce reactivity. Drops and becomes difficult to dissolve in water. The rate of the condensation reaction varies with pH and is generally slowest when the pH is 3.5-4.

  In addition to the pH, the reaction may be accelerated by the presence of a catalyst such as an organic metal, and it is effective to control the pH of the aqueous solution to around 4 in order to obtain a stable aqueous solution.

  Regarding the means to improve the impact strength of pot-shaped molded products, which are cooking utensils obtained by discharging molding material into the mold, especially the center of the bottom surface near the gate where fine cracks occur and the strength decreases The reforming means will be described in detail below.

  First, a method for producing a carbon aggregate forming raw material will be described. After adding a quaternary ammonium salt type cationic surfactant while stirring so that graphite particles of 0.3 mm or less obtained by crushing a block are uniformly dispersed in water, a phenol compound and an aldehyde compound are added. It poured so that 25 wt% phenol resin might adhere. Surfactant has protective colloid properties and exhibits polyelectrolyte behavior, forms an ion complex with an anionic water-soluble resin, and forms phenolic compounds inside the protective colloid with graphite grains as the core, that is, on the surface of the graphite grains And the aldehyde compound react to form a phenol resin in a spherical shape.

  As the quaternary ammonium salt type cationic surfactant that forms the protective colloid described above, alkyltrimethyl type and alkyldimethylbenzyl type cationic surfactants are preferable, and the alkyl part also has high purity such as lauryl, palmityl, stearyl and behenyl, Those having a C number of about 10 to 20 are effective.

  The reaction of the phenol resin was adjusted to the water temperature and the mixing time to be in an uncured state having a mode in which it was not melted at 160 ° C., which is the mold temperature at the time of molding, and exhibited a softened state. Also, the efficiency of resin adhesion to the graphite grains needs to be adjusted by the stirring speed. If it is too slow, the particles aggregate and enlarge, and if it is too fast, the resin adhering to the graphite grain surface will peel off and become independent. As a result, a spherical resin that has been cured is formed, so that the amount of adhesion on the surface of the graphite grains is reduced.

  After the phenolic resin has reached a semi-cured state and formed a complexed state coated on the surface of the desired graphite particles, this was filtered and recovered and dried with low-temperature hot air to obtain a raw material for forming a carbon aggregate .

  FIG. 1 is a diagram for comparison, and is a mixture obtained by pressure-kneading a carbon powder and a phenol resin uncured product obtained by crushing a lump by only kneading with a general molding raw material with an extruder or the like. It is a conceptual diagram of resin adhesion. FIG. 2 is a diagram showing the first embodiment, and is a conceptual diagram of a molding raw material in which an uncured phenol resin is complexed on the surface.

  As shown in FIG. 2, the carbon aggregate forming raw material obtained by the above-mentioned means is composed of carbon particles obtained by crushing a lump only by kneading with the general forming raw material shown in FIG. Compared with the resin adhesion of the mixture obtained by pressure kneading with an extruder or the like, it precipitates on the surface of the carbon particle 1 so as to cover the sharp end face of the carbon particle during the phenol resin polymerization process. However, the uncured phenol resin 2 forms a coating film and forms a smooth surface.

  For this reason, the carbon aggregate molding raw material according to the present embodiment retains the resin without melting in the mold when pressurized under heating at a molding temperature of about 160 ° C. and discharged into the mold. However, it is easy to move to a suitable position by filling the gap, that is, it has a feature of excellent fluidity.

  The molded product obtained by the above-described means was subjected to a calcination treatment at a stepwise temperature increase in an oxygen-free atmosphere up to 750 to 800 ° C. so that the decomposition gas of the phenol resin does not stay in the wall of the molded product. By the baking treatment in this temperature range, an aggregate having amorphous carbon containing impurities in which active groups slightly remain as a binder of graphite grains was obtained.

  Next, a silane coupling agent (preferably a methoxy or ethoxy group having a functional group as an amino group) is formed on the processing mark in which the gate of the molded product is excluded in the vicinity of the gate at the center of the bottom of the molded product. Silane coupling agent) and water (preferably a mixture of water and a low-boiling alcohol such as ethanol) was impregnated and dried at room temperature.

  In this state, after the silane coupling agent generates silanol (Si—OH) by hydrolysis, the silanols are condensed to form a silane oligomer having a siloxane bond (Si—O—Si). At this time, within the minute cracks of the molded product, the coupling agent having water and OH group and the active group in the slightly remaining impurities contained in the above-mentioned aggregate and the binder derived from phenol resin are combined. In a fixed state.

  At the stage where the silane coupling agent impregnated from the above-mentioned processing mark of the molded product gate was dried, the silicon compound was impregnated with silazane. Silazane reacts with water or silanol groups (Si-OH) adsorbed on the surface of the substrate to form a water-repellent layer composed of a coating containing silicon dioxide and an organic silazane compound, and does not disperse in a high-temperature atmosphere. It has the feature that it is held in the crack.

At this time, the silane coupling agent is preferably a methoxysilane having an amino group as a functional group. The silane coupling agent is weakly acidic, promotes hydrolysis and is converted into SiO ₂ , reacts with the remaining moisture, and is converted into silica glass. Therefore, fixing in the crack is further facilitated.

  The silicon compound used here may be polysilazane instead of silazane. In this case, it hydrolyzes easily when brought into contact with water or alcohol. The weight yield associated with this reaction has no separation of organic components other than hydrogen, and 2 moles of oxygen are substituted for 1 mole of nitrogen, resulting in an efficient reaction in which the yield is as high as about 130%. .

  Addition of amines as a catalyst is effective, and xylene, mineral terpenes, and high-boiling aromatic solvents that do not contain OH groups and contain less water in order to reduce viscosity for efficient impregnation. Are preferable from the viewpoint of securing solubility, stability, and stable coating properties.

  Next, the carbon coagulation body used for the cooking utensil of the present embodiment was obtained by performing a second baking process at 1200 ° C. or higher. The silicon dioxide and the silica glass are decomposed in the stage of the second baking treatment, so that the silicon carbide (SiC) having an excellent strength reacts with the amorphous carbon in which the impurities in which the active groups remain slightly remain. An amorphous material is produced, and a high-strength composite is formed without impairing the bond with graphite. The reaction proceeds in the range of 1100 ° C. to 1500 ° C., preferably 1200 to 1300 ° C., and an aspect in which the resistance to impact fracture is improved by reinforcing the crack portion that becomes the fracture initiation portion is obtained.

  FIG. 3 is a diagram showing the first embodiment, and shows a comparison result of the falling ball strength (breaking height) in the center portion of the bottom surface, which is a modified portion, in Examples 1 and 2 and Comparative Examples 1 to 4.

  Samples with modified surface modification conditions of silicon compound and firing conditions are prepared as comparative examples, and the falling ball strength (breaking height) at the center of the bottom surface, which is the modified portion of these samples, is measured. The effectiveness of this embodiment Was confirmed (see FIG. 3).

  The falling ball strength was shown as the falling ball strength which is the maximum height at which a 200 g steel ball is dropped to the center of the bottom surface corresponding to the gate position of the aggregate molded product and does not lead to breakage such as crack generation.

  A carbon aggregate molded product having a first baking temperature of 800 ° C., a mixture of water, ethanol, and a silane coupling agent (3-aminopropyltrimethoxysilane) (respectively, etc.) on a processing mark in the vicinity of the gate at the center of the bottom surface Amount) and dried at room temperature, and then a silazane or polysilazane which is a silicon compound was applied. Then, what was heat-processed by the 2nd baking temperature of 1200 degreeC was made into Example 1 (application | coating silazane) and Example 2 (application | coating polysilazane) which are the surface modification methods of this Embodiment.

  On the other hand, a silicon compound is not applied (Comparative Example 1), a first baking temperature is set to 900 ° C. of 800 ° C. or higher (Comparative Example 2), and a second baking temperature is 1000 ° C. of 1100 ° C. or lower. (Comparative Example 3) and the second baking temperature set to 1600 ° C. (Comparative Example 4) were used as comparative examples, and the examples were similar to those of the examples except for the changing conditions.

  As shown in the above results, the carbon aggregate surface modifying means according to the present embodiment has a first calcination temperature of 800 ° C. and a silane coupling in the vicinity of the gate of the carbon aggregate containing fine cracks. After the agent was hydrolyzed, it was impregnated with a silicon compound, dried, and then fired at 1200 ° C. As a result, the crack portion is repaired with an increase in the weight yield of silazane, and silicon carbide is generated by a reaction with amorphous carbon in the subsequent baking treatment. The resulting fine cracks can be reinforced to improve the impact strength.

  On the other hand, in the case of a carbon aggregate molded product which is a cooking utensil without any surface modification of Comparative Example 1, it is generated by the release behavior of the residual strain caused by the molding material in the vicinity of the gate at the center of the bottom surface. The cracked ball impact strength was extremely low as the crack acted as a starting point of fracture.

  On the other hand, in Comparative Example 2, as a result of the fact that many of the impurities derived from the phenol resin and containing functional groups were scattered and silanol (Si—OH) was scattered, the amount of silicon carbide produced was finally insufficient, which was sufficient. Insufficient surface modification was achieved.

  Further, in Comparative Example 3, silanol or silica glass was not sufficiently converted to silicon carbide, and in Comparative Example 4, the generated silicon carbide was crystallized and dissociated from graphite. As a major factor, it was confirmed that the effect of sufficient surface modification was not exhibited.

  In this example, silazane (Example 1) or polysilazane (Example 2) was used as the silicon compound, but instead of this, low-temperature curing (Pd (palladium) compound as a dehydrogenation and oxidation catalyst was added ( Silica conversion) type polysilazane or perhydropolysilazane which reacts with moisture in the air and easily converts to silica glass may be used.

  Moreover, since a hydrolysis is accelerated | stimulated by using the composition provided with the acetoxy group and the halogen group as a silane coupling agent, what is necessary is just to select it suitably.

  1 carbon powder, 2 uncured phenol resin.

Claims (6)

Is graphite grains of aggregates of carbon was bound material phenol origin of the carbon aggregates pot-shaped molded article was fired in an oxygen-free atmosphere at 800 ° C. or less, the gate corresponding parts on the bottom center of the pan-shaped molded article after a silicon compound impregnated into, the surface modification method of the carbon sintered body, characterized that you heat the pot-shaped molded product in an oxygen-free atmosphere at from 1100 to 1,500 ° C.. The pot-shaped molded article of the heating, the surface modification method of a carbon sintered body according to claim 1, characterized that you heat the pot-shaped molded product in an oxygen-free atmosphere at 1200 to 1300 ° C.. The method for modifying the surface of a carbon sintered body according to claim 1 or 2 , wherein the silicon compound is silazane or polysilazane.   The surface modification of the carbon sintered body according to claim 1 or 2, wherein the impregnation of the silicon compound is impregnated with a mixture of a silane coupling agent and water and impregnated with silazane or polysilazane after drying. Method.   The method for modifying the surface of a carbon sintered body according to claim 1 or 2, wherein the impregnation of the silicon compound is impregnated with water containing a trace amount of lower alcohol, and impregnated with silazane or polysilazane after drying. Comprising a carbon aggregate pot-shaped molded article is a condensation of the carbon phenol origin binder and the graphite grain, from silicon compounds into cracks present in the gate corresponding parts on the bottom center of the pan-shaped molded article electromagnetic induction heating cooker according to claim silicon carbide including that.

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