JP2007230820A - Silicon carbide composite sintered compact and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silicon carbide composite sintered compact reducing the friction to a counter member and the wear resistance by exhibiting the cushioning property to load stress in sliding and improving the supportability of a lubricant under a lubrication condition using water, oil or the like and particularly excellent in slidability under no lubrication in air to be suitable as a sliding member such as a mechanical seal. <P>SOLUTION: In the silicon carbide composite sintered compact obtained by dispersing carbon powder in silicon carbide, the carbon powder is a porous carbonized powder having a surface a part of which is covered with a carbonized coating film and the blending quantity of the carbon powder is 3-17 pts.mass per 100 pts.mass silicon carbide. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a silicon carbide composite sintered body in which carbon powder is dispersed in silicon carbide and a method for manufacturing the same.

Conventionally, since silicon carbide is excellent in hardness, heat resistance, and corrosion resistance, application as a structural member has been studied. In particular, it is practically used for mechanical seals and the like because of its good sliding property in water. However, silicon carbide has a large coefficient of friction under no lubrication in the atmosphere, has a high attacking property against a sliding mating member (hereinafter referred to as a mating material aggression), and is liable to cause a lubricant film breakage. Is limited.
In order to solve such a problem, a technique for improving sliding characteristics by combining carbon with silicon carbide ceramics as a base material has been developed.
As a conventional technique, (Patent Document 1) states that “carbonization is contained in 10 to 50 parts by weight of carbon with respect to 100 parts by weight of silicon carbide, and has 5 to 50% by volume of open pores (average diameter 0.05 to 10 μm). A slidable composite material in which an open pore portion of a silicon-carbon composite material is filled with a substance having lubricity in 10% by volume or more of the open pore portion capacity is disclosed.
(Patent Document 2) states that “the average particle size is 0.001 to 0.080 mm in size and contains 3 to 30 vol% of carbon powder having pores, with the balance being silicon carbide and a sintering aid. There is disclosed a “sliding member in which carbon formed in a sintered body contained therein and interspersed on the sliding surface of the sintered body is formed in a recess”.
(Patent Document 3) states that “a sliding part of a sintered body that slides relative to each other, having carbon particles scattered on the sliding surface of the sliding part and the surface of the carbon particle There is disclosed a “sliding component having pores formed in a concave portion from a sliding surface and having fine pores in the carbon particles on the bottom surface of the pores”.
Japanese Patent Laid-Open No. 9-165281 JP 2003-42305 A Japanese Patent Laid-Open No. 2004-116587

However, the above conventional techniques have the following problems.
(1) Since the technique disclosed in (Patent Document 1) uses an impregnation method such as vacuum impregnation or high-pressure impregnation to impregnate and fill the open pores of the silicon carbide-carbon composite material with a lubricant, productivity is high. It has the problem of being low.
(2) The technology disclosed in (Patent Document 2) and (Patent Document 3) is such that a liquid such as a lubricating oil soaks into carbon powder having pores in a sintered body and lubricates the sliding surface over a long period during sliding. Although lubricating function is exhibited by supplying oil or the like, there is a problem in that the amount of the lubricating oil soaked into the carbon powder varies, so that the stability during sliding is lacking.
(3) The technology disclosed in (Patent Document 3) is a manufacturing process in which a sliding surface interspersed with carbon powder is heated in an air atmosphere and the surface of the carbon powder is burned to form a large number of fine pores. However, it has the subject that productivity is low and productivity is low.
(4) In the technologies disclosed in (Patent Document 1) to (Patent Document 3), the carbon powder combined with silicon carbide is soft and has low hardness. When mixed with the above, the composite sintered body easily breaks down and has a problem that the obtained composite sintered body lacks the effect of mitigating the load stress by the carbon powder and the effect of mitigating the attack of the counterpart material.

The present invention solves the above-mentioned conventional problems, exhibits cushioning properties against load stress during sliding, and improves the supportability of the lubricant under lubrication conditions such as water and oil, so that the counterpart An object of the present invention is to provide a silicon carbide composite sintered body that can reduce the material aggression and the specific wear amount of the self material, and that is excellent in slidability especially in the air without lubrication.
In the present invention, the degreased molded body is once pressed by a cold isostatic pressing method (CIP) and then sintered, so that a hot isostatic pressing method (HIP) or a hot press method (HP) is performed. It is an object of the present invention to provide a method for producing a silicon carbide composite sintered body capable of producing a high-density composite sintered body by atmospheric pressure sintering without requiring large-scale equipment such as

In order to solve the above conventional problems, the silicon carbide composite sintered body and the method for producing the same of the present invention have the following configurations.
The invention according to claim 1 of the present invention is a silicon carbide composite sintered body in which carbon powder is dispersed in silicon carbide, and the carbon powder is a porous carbonized powder in which at least a part of the surface is coated with a carbonized film. The blending amount of the carbon powder is 3 to 17 parts by mass with respect to 100 parts by mass of the silicon carbide.
With this configuration, the following effects can be obtained.
(1) Since the carbon powder has at least a part of the surface of the porous carbonized powder coated with the carbonized film, the porous carbonized powder is produced when the silicon carbide composite sintered body is manufactured, particularly when mixed with silicon carbide. Is prevented from being broken and miniaturized. As a result, when a silicon carbide composite sintered body containing carbon powder is used as a sliding member, the porous carbonized powder exhibits a cushioning property against load stress during sliding, and under lubricating conditions such as water and oil In order to improve the supportability of the lubricant, the counterpart material attack and the specific wear amount of the own material can be reduced.
(2) Since the blending amount of the carbon powder is adjusted to a specific range, the silicon carbide composite sintered body of the present invention is excellent in slidability under no lubrication in the atmosphere.

The carbon powder of the present invention is not particularly limited as long as at least a part of the surface thereof is a porous carbonized powder coated with a carbonized film. For example, as will be described later, potatoes such as defatted soot and soot and thermosetting A carbide obtained by firing a granulated product obtained by kneading and granulating a synthetic resin such as a resin or a thermoplastic resin is preferable.
By carbonizing a granulated product composed of moss and synthetic resin such as thermosetting resin and thermoplastic resin, the surface of moss-derived porous carbide (porous carbonized powder) is derived from synthetic resin. A carbon powder having a structure coated with a glassy carbonized layer (carbonized film) is obtained.
The carbonized film has an effect of suppressing the destruction of the porous carbonized powder. Therefore, it is preferable that the carbonized film covers at least a part of the porous carbonized powder, but in order to increase the effect, it is more preferable to cover substantially the entire surface or the entire surface of the porous carbonized powder.

  As for the compounding quantity of carbon powder, 3-17 mass parts is preferable with respect to 100 mass parts of silicon carbide. If the blending amount of the carbon powder is less than 3 parts by mass, the slidability of the composite sintered body in the air without lubrication is reduced. If it is more than 15 parts by mass, the strength and rigidity of the composite sintered body are reduced. Specific wear increases. A more preferable blending amount of the carbon powder is 5 to 15 parts by mass.

  The average particle size of the carbon powder is preferably 10 to 100 μm. When the average particle size is smaller than 10 μm, the cushioning property against the load stress at the time of sliding and the supportability of the lubricant are lowered, and when larger than 100 μm, the sinterability with silicon carbide is lowered, so the mechanical strength of the composite sintered body is reduced. Decreases and the specific wear increases. A more preferable average particle diameter is 20 to 80 μm.

Silicon carbide is not particularly limited, and both α-type and β-type crystal types can be used. The purity of silicon carbide is preferably 90% by mass or more, more preferably 95% by mass or more for reasons such as preventing the decrease in density, strength, and fracture toughness of the composite sintered body.
The average particle size of silicon carbide is preferably 0.05 to 10 μm. When the average particle size is larger than 10 μm, the mechanical strength is lowered and the particles are shed when sliding, and the slidability is impaired. On the other hand, if the average particle size is less than 0.05 μm, the particles are aggregated and the handleability is lowered. A more preferable average particle diameter is 0.1 to 5 μm.

The invention according to claim 2 of the present invention is the silicon carbide composite sintered body according to claim 1, wherein the average thickness of the carbonized coating is 1/20 to 1/5 of the average particle diameter of the carbon powder. It is characterized by being.
With this configuration, the following operation is obtained in addition to the operation of the first aspect.
(1) Since the average thickness of the carbonized film is limited to a specific range, the porous carbonized powder is more stable and sufficiently present in the silicon carbide composite sintered body without being finely divided. A silicon carbide composite sintered body that further relaxes the specific wear amount of the own material is obtained.

    The average thickness of the carbonized film is preferably 1/20 to 1/5 of the average particle diameter of the carbon powder. When the average thickness of the carbonized film is less than 1/20 of the average particle diameter of the carbon powder, the hardness of the carbonized film decreases, and when the composite sintered body is manufactured, particularly when mixed with silicon carbide, it is destroyed and refined. easy. Also, if the average thickness of the carbonized film is thicker than 1/5 of the average particle diameter of the carbon powder, the particle diameter of the porous carbonized powder becomes relatively small, and cushioning against load stress during sliding and support of lubricant Sex is reduced.

The invention according to claim 3 of the present invention is the silicon carbide composite sintered body according to claim 1 or 2, wherein the porous carbonized powder has pores having an average pore diameter of 0.5 to 5 μm. Features.
With this configuration, in addition to the operation of the first or second aspect, the following operation can be obtained.
(1) Since the porous carbonized powder has pores having a specific average pore diameter, the silicon carbide composite sintered body is superior in cushioning properties against load stress and sliding ability of a lubricant during sliding.

The average pore diameter of the pores of the porous carbonized powder is preferably 0.5 to 5 μm. When the average pore diameter is smaller than 0.5 μm, the composite sintered body has a reduced cushioning property against the load stress during sliding and the carrying ability of the lubricant. When the average pore diameter is larger than 5 μm, the porous carbonized powder The mechanical strength and hardness are reduced, and the carbon powder is easily broken during sliding.
The average pore diameter of the porous carbonized powder is determined by using a scanning electron microscope (SEM), the surface of the carbon powder (porous carbonized powder) not covered with the carbonized film, or the carbon powder (porous carbonized powder). It can be determined by measuring the pore size distribution such as the cross section.

The invention according to claim 4 of the present invention is the silicon carbide composite sintered body according to any one of claims 1 to 3, wherein the carbon powder includes mosses, thermosetting resins, and thermoplastics. It is a carbide obtained by carbonizing a granulated product obtained by kneading and granulating a synthetic resin such as a resin in an inert gas atmosphere under normal pressure or in an air atmosphere under reduced pressure at a temperature of 700 to 1100 ° C. It is characterized by.
With this configuration, the following operation is obtained in addition to the operation of any one of claims 1 to 3.
(1) The carbon powder is obtained by carbonizing a granulated product of a moss having pores of an appropriate diameter inside and a synthetic resin that is vitrified into a hard carbonized film under predetermined conditions. A silicon carbide composite sintered body that further relaxes the material aggression and the specific wear amount of the self material can be obtained.
(2) Since moss that has been disposed of in large quantities can be effectively used as an industrial material, it is excellent in resource saving.

Koji is a defatted koji after squeezing rice koji oil, koji that remains as flesh when milled into flour, gluten feed that is a residue when corn starch is produced, koji, oats, soybeans, etc. Peeling shells generated during the processing of, and those obtained by pulverizing them are preferred.
Synthetic resins include thermosetting resins such as thermosetting phenol resins, urea resins, melamine resins, unsaturated polyester resins, and epoxy resins, and thermoplastic resins such as thermoplastic phenol resins, tar, polyethylene, polypropylene, polystyrene, and polyethylene terephthalate. It is preferable to use resins alone or in combination, and it is particularly preferable to use tar, phenol resin, furan resin, polyacrylonitrile or the like having a carbonization rate of 40% or more in order to obtain a hard carbonized film.
Synthetic resins can be used in the form of powder or liquid, but the porous carbonized powder and the carbonized coating are firmly bonded, and the surface of the porous carbonized powder is more uniformly coated with the carbonized coating. In particular, the liquid form is preferable.

The blending ratio of the synthetic resin such as thermosetting resin or thermoplastic resin is preferably 80% by mass or less with respect to 100% by mass of the total amount of the synthetic resin and the moss.
When the blending ratio is more than 80% by mass, the average thickness of the obtained carbonized film becomes thick, so the particle size of the porous carbonized powder becomes relatively small, and the cushioning property against the load stress when the composite sintered body slides, Lubricant support is reduced.
The average thickness of the carbonized film obtained can be adjusted by adjusting the blending ratio of moss and synthetic resin.

In order to adjust the particle size of the obtained carbon powder, the size of the granulated product is preferably 12 mesh (aperture 1.4 mm) or less, and more preferably 20 mesh (aperture 850 μm) or less.
In addition, in the case of granulation, in order to improve the moldability and intensity | strength of a granulated material, a binder can be added as needed. Although the kind of binder is not specifically limited, For example, starch, molasses, lignin, polyvinyl alcohol, methylcellulose, organic substances, such as a pulp waste liquid, water, etc. can be used. The addition amount of the binder is not particularly limited. However, in consideration of the addition effect and cost, the addition amount is preferably 0.5 to 10% by mass with respect to 100% by mass of the total amount of moss and synthetic resin.

  The granulated product is carbonized at a temperature of 700 to 1100 ° C., more preferably 800 to 1000 ° C. in an inert gas atmosphere such as nitrogen gas or in an air atmosphere under reduced pressure so that the moss and the synthetic resin are not burned off. . When the carbonization temperature is lower than 700 ° C or higher than 1100 ° C, the hardness of the obtained carbon powder is lowered. In addition, since a large amount of gas is generated with decomposition of moss and the like, it is preferable to raise and heat at a moderate rate of 1 to 5 ° C./min until the carbonization temperature reaches 700 ° C. or higher.

  As for the pressure reduction conditions at the time of carbonization in an air atmosphere, 1-100 Pa is preferable. When the pressure is lower than 1 Pa, the vacuum pump is enlarged and time is required for pressure reduction, so that productivity is lowered. When the pressure is higher than 100 Pa, moss and synthetic resin are burned out by residual air.

Invention of Claim 5 of this invention is a manufacturing method of the silicon carbide compound sintered compact which disperse | distributed carbon powder to silicon carbide, Comprising: From the porous carbonized powder by which at least one part of the surface was coat | covered with the carbonized film A mixing step of mixing a carbon powder and silicon carbide to obtain a mixed powder, a forming step of forming the mixed powder to obtain a formed body, and heating and degreasing the formed body at a temperature of 600 to 1100 ° C. A degreasing step for obtaining a degreased molded body, a pressing step for pressurizing the degreased molded body by a cold isostatic pressing method, and heating and baking the degreased molded body pressed in the pressing step at 1800 to 2200 ° C. And a sintering step of obtaining a sintered body by bonding.
With this configuration, the following effects can be obtained.
(1) Since the carbon powder has at least a part of the surface of the porous carbonized powder coated with the carbonized film, the porous carbonized powder is produced when the silicon carbide composite sintered body is manufactured, particularly when mixed with silicon carbide. Is prevented from being broken and miniaturized. As a result, when a silicon carbide composite sintered body containing carbon powder is used as a sliding member, the porous carbonized powder exhibits a cushioning property against load stress during sliding, and under lubricating conditions such as water and oil In order to improve the supportability of the lubricant, the counterpart material attack and the specific wear amount of the own material can be reduced.
(2) Since the degreased molded body is once pressed by the cold isostatic pressing method (CIP) and then sintered, a high-density silicon carbide composite sintered body can be produced by normal pressure sintering.
(3) Although it is possible to produce a high-density composite sintered body by hot isostatic pressing (HIP), hot pressing (HP), etc., the production method of the present invention does not require such a large scale. Excellent economic effect in that no equipment is required.

In the mixing step, as long as the carbon powder can be uniformly mixed with silicon carbide, it may be mixed under any conditions. However, when mixing, it is preferable that the carbon powder is mixed under conditions that make it difficult for the carbon powder to break down and become fine. preferable. As a specific example of the mixer, it is preferable to use a ball mill, a V-type mixer or the like.
Further, if necessary, a sintering aid such as an organic binder or a boron compound for improving the moldability can be added.

  In the molding process, various conventionally known molding methods can be used. For example, a casting molding method, an extrusion molding method, a uniaxial pressure molding method, a cold isostatic pressing method (CIP), and an injection molding method. It is preferable to use a molding method such as

In the degreasing step, the molded body is heated and degreased at a temperature of 600 to 1100 ° C, more preferably 700 to 1000 ° C in an air atmosphere under reduced pressure or in an inert gas atmosphere under normal pressure to obtain a degreased molded body. By this degreasing treatment, moisture and undecomposed organic compounds in the carbon powder are decomposed and gasified, so that the relative density of the composite sintered body can be finally increased to 94 to 99%.
Regarding the atmospheric conditions and pressure conditions in the degreasing step, 60 Pa or less is particularly preferable in an air atmosphere in that the decomposition of the undecomposed organic compound can be promoted without burning off the carbon powder. When the pressure is higher than 60 Pa, evaporation / dissipation of the cracked gas is not promoted, and the carbon powder is easily burned off.
Regarding the temperature condition, if the degreasing temperature is lower than 600 ° C., gas is generated in the sintering process due to insufficient decomposition of the undecomposed organic compound contained in the carbon powder. When the temperature is higher than 1100 ° C., the carbon powder is decomposed and burned out.

    In the pressurizing step, the pressure of the cold isostatic pressing method (CIP) is preferably 100 to 200 MPa. If the pressure is lower than 100 MPa, the increase in density due to pressurization is small, and conversely, even if the pressure is higher than 200 MPa, the increase in density is small, and there is a demerit that the service life of the pressurizer is shortened. . A more preferable pressure is 130 to 180 MPa.

In the sintering step, a method in which the degreased molded body obtained in the pressurizing step is sintered in an inert gas atmosphere under normal pressure or an air atmosphere under reduced pressure using an inert gas such as argon, helium, or nitrogen is preferable.
The pressure condition in the air atmosphere is preferably 1 to 100 Pa. When the pressure is lower than 1 Pa, the vacuum pump used for depressurization increases in size, and time is required for depressurization, resulting in a decrease in productivity. When the pressure is higher than 100 Pa, carbon powder and silicon carbide are decomposed by residual air, and the density of the composite sintered body is lowered.
The sintering temperature is preferably 1800 to 2200 ° C. If the sintering temperature is lower than 1800 ° C., the mechanical properties are remarkably lowered due to insufficient sintering, and if it is higher than 2200 ° C., abnormal grain growth of silicon carbide occurs. As a result, the mechanical properties deteriorate.

    Invention of Claim 6 of this invention is a manufacturing method of the silicon carbide compound sintered compact of Claim 5, Comprising: The compounding quantity of the said carbon powder is 3-17 with respect to 100 mass parts of said silicon carbide. It is a mass part.

With this configuration, the following operation is obtained in addition to the operation of the fifth aspect.
(1) Since the blending amount of the carbon powder is adjusted to a specific range, the obtained silicon carbide composite sintered body is excellent in slidability under no lubrication in the atmosphere.

    Invention of Claim 7 of this invention is a manufacturing method of the silicon carbide compound sintered compact of Claim 5 or 6, Comprising: The average thickness of the said carbonized film is 1 of the average particle diameter of the said carbon powder. / 20 to 1/5.

With this configuration, in addition to the operation of the fifth or sixth aspect, the following operation can be obtained.
(1) Since the average thickness of the carbonized film is limited to a specific range, the porous carbonized powder can be stably and sufficiently present in the silicon carbide composite sintered body without being miniaturized. A silicon carbide composite sintered body that further relaxes the properties and the specific wear amount of the material itself can be obtained.

    Invention of Claim 8 of this invention is a manufacturing method of the silicon carbide compound sintered compact of any one of Claim 5 thru | or 7, Comprising: The said porous carbide | carbonized_material powder is 0.5-0.5 in average diameter. It has 5 μm pores.

With this configuration, in addition to the operation of any one of claims 5 to 7, the following operation can be obtained.
(1) Since the porous carbonized powder has pores having a specific average pore size, a silicon carbide composite sintered body that is superior in cushioning property against load stress during sliding and in carrying a lubricant can be obtained.

    Invention of Claim 9 of this invention is a manufacturing method of the silicon carbide composite sintered compact of any one of Claim 5 thru | or 8, Comprising: The said carbon powder is moss and thermosetting resin , Carbide obtained by carbonizing a granulated product obtained by kneading and granulating with a synthetic resin such as a thermoplastic resin at 700 to 1100 ° C. in an inert gas atmosphere under normal pressure or in an air atmosphere under reduced pressure It is characterized by being.

With this configuration, the following operation is obtained in addition to the operation of any one of claims 5 to 8.
(1) Since a carbon powder obtained by carbonizing a granulated product of a moss having pores of an appropriate diameter inside and a synthetic resin that is vitrified to form a hard carbonized film under a predetermined condition is used, the opponent material is aggressive In addition, a silicon carbide composite sintered body that further relaxes the specific wear amount of the own material can be obtained.
(2) Since moss that has been disposed of in large quantities can be effectively used as an industrial material, it is excellent in resource saving.

As described above, according to the silicon carbide composite sintered body and the manufacturing method thereof of the present invention, the following advantageous effects can be obtained.
According to the invention of claim 1,
(1) When the composite sintered body containing the carbon powder of the present invention is used as a sliding member, cushioning properties against load stress during sliding are exhibited by the porous carbonized powder, and lubrication conditions such as water and oil are used. Then, since the carrying property of the lubricant is improved, it is possible to provide a silicon carbide composite sintered body capable of reducing the attacking property of the counterpart material and the specific wear amount of the own material.
(2) A silicon carbide composite sintered body excellent in slidability under non-lubrication in the atmosphere can be provided.

According to invention of Claim 2, in addition to the effect of Claim 1,
(1) Since the silicon carbide composite sintered body is sufficiently and stably present in the silicon carbide composite sintered body without being miniaturized, the silicon carbide composite sintering further mitigates the counterpart material attack and the specific wear amount of the own material. Can provide the body.

According to invention of Claim 3, in addition to the effect of Claim 1 or 2,
(1) Since the porous carbonized powder has pores having a specific average pore diameter, it is possible to provide a silicon carbide composite sintered body that is superior in cushioning properties against load stress during sliding and in carrying lubricant.

According to the invention of claim 4, in addition to the effect of any one of claims 1 to 3,
(1) The carbon powder is obtained by carbonizing a granulated product of a moss having pores of an appropriate diameter inside and a synthetic resin that is vitrified into a hard carbonized film under predetermined conditions. It is possible to provide a silicon carbide composite sintered body that can further alleviate the material attack and the specific wear amount of the self material.
(2) A silicon carbide composite sintered body excellent in resource saving can be provided by effectively utilizing potatoes that have been discarded in large quantities as an industrial material.

According to the invention of claim 5,
(1) When the composite sintered body containing the carbon powder of the present invention is used as a sliding member, cushioning properties against load stress during sliding are exhibited by the porous carbonized powder, and lubrication conditions such as water and oil are used. Then, since the carrying property of the lubricant is improved, it is possible to provide a method for producing a silicon carbide composite sintered body from which a silicon carbide composite sintered body capable of reducing the attack of the counterpart material and the specific wear amount of the own material can be obtained.
(2) Since the degreased molded body is once pressed by the cold isostatic pressing method (CIP) and then sintered, carbonization capable of producing a high-density silicon carbide composite sintered body by atmospheric pressure sintering A method for producing a silicon composite sintered body can be provided.
(3) A method for producing a silicon carbide composite sintered body that does not require a large-scale facility such as a conventionally known hot isostatic pressing method (HIP) or hot press method (HP) and is excellent in economic effect. Can provide.

According to the invention described in claim 6, in addition to the effect of claim 5,
(1) A method for producing a silicon carbide composite sintered body from which a silicon carbide composite sintered body excellent in slidability under non-lubrication in the atmosphere can be provided.

According to invention of Claim 7, in addition to the effect of Claim 5 or 6,
(1) Since silicon carbide composite powder can be made to exist in a stable and sufficiently porous carbide powder without making it fine, silicon carbide that further reduces the aggressiveness of the counterpart material and the specific wear amount of the material itself A method for producing a silicon carbide composite sintered body from which a composite sintered body can be obtained can be provided.

According to the invention described in claim 8, in addition to the effect of any one of claims 5 to 7,
(1) Since the porous carbonized powder has pores having a specific average pore diameter, a silicon carbide composite fired product can be obtained in which a silicon carbide composite sintered body excellent in cushioning properties against load stress during sliding and carrying of a lubricant is obtained. A method for producing a knot can be provided.

According to invention of Claim 9, in addition to the effect of any one of Claims 5 to 8,
(1) Since a carbon powder obtained by carbonizing a granulated product of a moss having pores of an appropriate diameter inside and a synthetic resin that is vitrified to form a hard carbonized film under a predetermined condition is used, the opponent material is aggressive And the manufacturing method of the silicon carbide composite sintered compact from which the silicon carbide composite sintered compact which relieves | releasing the specific wear amount of a self-material further can be provided.
(2) A method for producing a silicon carbide composite sintered body excellent in resource saving can be provided by effectively utilizing wastes that have been discarded in large quantities as an industrial material.

Hereinafter, the present invention will be specifically described by way of examples. The present invention is not limited to these examples.
Example 1
A defatted soot that has passed through a 48 mesh (mesh opening 300 μm) sieve and a thermosetting phenolic resin (manufactured by Gunei Chemical Industry Co., Ltd., trade name: Liquid Resid Top PL-4826) are thermally cured on 76 parts by weight of the defatted soot. After mixing and kneading at a ratio of 24 parts by weight of the phenolic resin, it was granulated while heating to 80 ° C. Among the obtained granulated material, a material that passed through a 12 mesh (1.4 mm opening) sieve was carbonized at 900 ° C. in a nitrogen gas atmosphere and then pulverized to obtain a carbon powder. The average particle size of the obtained carbon powder was 40 μm.
FIG. 1 is an example of a scanning electron microscope (SEM) photograph of carbon powder, and FIG. 2 is an enlarged scanning electron microscope (SEM) photograph of a part of FIG.
According to FIG. 1, the maximum particle diameter of the carbon powder is about 100 μm, and it can be seen that the carbonized film on the surface has a relatively smooth glassy structure.
The carbon powder shown in FIG. 2 has a particle size of about 90 μm, and only a part of the upper surface has a smooth structure, and the lower side has a porous structure. It is assumed that a part of the glass-like carbonized film coated with the porous carbonized powder is peeled off. The thickness of the carbonized film is about 5 μm, and pores having an average diameter of 0.5 to 5 μm are formed on the surface of the porous carbonized powder. Since the average particle diameter of the carbon powder was 40 μm and the thickness of the carbonized film was about 5 μm, the ratio of the thickness of the carbonized film to the carbon powder (5 μm) was 5/40 = 1/8.
Next, 0.5 parts by mass of boron carbide and 1 part by mass of carbon were added as a sintering aid to a mixture of 3 parts by mass of the aforementioned carbon powder with respect to 100 parts by mass of silicon carbide having an average particle size of 0.7 μm. Then, wet mixing was performed for 24 hours in a ball mill in toluene (mixing step). After drying, the mixed powder was pressed at a pressure of 150 MPa by a cold isostatic pressing method to obtain a flat molded body (molding step). The obtained molded body was heated to 900 ° C. at a heating rate of 300 ° C./hour in an air atmosphere of 26 Pa and held for 1 hour, and then cooled to room temperature to obtain a degreased molded body (degreasing step). ). The obtained degreased molded body was pressurized again by a cold isostatic pressing method at 150 MPa (pressurizing step). The pressurized degreased molded body was heated to 1500 ° C. at a temperature rising rate of 300 ° C./hour in an air atmosphere under a reduced pressure of 26 Pa, and then replaced with an argon atmosphere of 0.1 MPa at 1500 ° C., and then 2050 The silicon carbide composite sintered body of Example 1 was obtained by sintering at atmospheric pressure for 2 hours at normal pressure (sintering step).

(Example 2)
A silicon carbide composite sintered body of Example 2 was obtained in the same manner as Example 1 except that 5 parts by mass of carbon powder was blended with 100 parts by mass of silicon carbide.
3 is a scanning electron microscope (SEM) photograph of the cut surface of the silicon carbide composite sintered body of Example 2, and FIG. 4 is a scanning electron microscope in which the cut surfaces of the carbon powder scattered in FIG. 3 are enlarged. (SEM) Photograph.
As can be seen from FIG. 3, the carbon powder is uniformly dispersed in the silicon carbide composite sintered body. Moreover, according to FIG. 4, the carbonized film of carbon powder peels by cutting | disconnection of a silicon carbide composite sintered compact, and the porous carbonized powder part has appeared.

(Example 3)
A silicon carbide composite sintered body of Example 3 was obtained in the same manner as Example 1 except that 11 parts by mass of carbon powder was blended with 100 parts by mass of silicon carbide.

Example 4
A silicon carbide composite sintered body of Example 4 was obtained in the same manner as Example 1 except that 17 parts by mass of carbon powder was blended with 100 parts by mass of silicon carbide.

(Comparative Example 1)
A silicon carbide composite sintered body of Comparative Example 1 was obtained in the same manner as in Example 1 except that 2 parts by mass of carbon powder was blended with 100 parts by mass of silicon carbide.

(Comparative Example 2)
A silicon carbide composite sintered body of Comparative Example 2 was obtained in the same manner as in Example 1 except that 20 parts by mass of carbon powder was blended with 100 parts by mass of silicon carbide.

(Comparative Example 3)
A fired body obtained by firing petroleum pitch at 1000 ° C. was pulverized and sized to obtain carbon powder (average particle size 100 μm). A silicon carbide composite sintered body of Comparative Example 3 was obtained in the same manner as in Example 1 except that 11 parts by mass of the obtained carbon powder was blended with respect to 100 parts by mass of silicon carbide.

(Comparative Example 4)
To 100 parts by mass of silicon carbide powder having an average particle size of 0.7 μm, 0.5 parts by mass of boron carbide and 1 part by mass of carbon were added as sintering aids, and wet mixed in a ball mill in toluene for 24 hours. After drying, the mixed powder was pressed at a pressure of 150 MPa by a cold isostatic pressing method to obtain a molded body. The obtained molded body was heated and heated to 900 ° C. at a temperature rising rate of 300 ° C./hour in an air atmosphere of 26 Pa for 1 hour, and then cooled to room temperature to obtain a degreased molded body. The obtained degreased molded body was again pressed by a cold isostatic pressing method at a pressure of 150 MPa. The pressurized degreased molded body was heated to 1500 ° C. at a heating rate of 300 ° C./hour under a reduced pressure of 26 Pa, then replaced with a 0.1 MPa argon atmosphere, and again heated to 2050 ° C. Then, after holding for 2 hours, it was cooled to room temperature to obtain a silicon carbide sintered body of Comparative Example 4.

(Specific wear amount without lubrication in the atmosphere)
For each of the sintered bodies of Examples 1 to 4 and Comparative Examples 1 to 4, the specific wear amount in the air without lubrication was measured as follows.
A reciprocating wear test apparatus (manufactured by Shinto Kagaku Co., Ltd., HEIDO-22 type) was used for the test. The test method consists of fixing each sintered body to the stage as a plate-shaped test piece, applying a load to the ball-shaped test piece placed on the plate-shaped test piece using a weight, and moving the stage at a constant sliding speed. A wear test was performed by reciprocating. As the ball-shaped test piece, an alumina polishing sphere having a radius of 4 mm (bulk density 3.9 g / cm ³ , Vickers hardness 18 GPa) was used. The sliding speed was 0.01 m / s, the number of friction repetitions was 20000, and the reciprocating stroke was 5 mm.
The specific wear amount was used for evaluation of wear resistance. Here, the specific wear amount is a wear volume per unit load and unit slip distance, and a calculation formula of V / (W · L) (V: wear volume [mm ³ ], W: vertical load [N], L: sliding distance [mm]).
After the test, the wear resistance of the plate-like test piece was measured with a stylus type surface roughness shape measuring instrument (manufactured by Tokyo Seimitsu, Surfcom 1400A-3DF type), and the plate-like test piece was determined from the cross-section curve. The wear volume was calculated. Furthermore, the specific wear amount of the plate-like test piece was calculated from the wear volume, the load applied during the test, and the sliding distance.
The specific wear amount of the ball-shaped test piece was also calculated from the wear volume of the ball-shaped test piece, the load applied during the test, and the sliding distance.

(Specific wear amount under water lubrication)
In each of the sintered bodies, friction between the plate-like test piece and the ball-like test piece was performed under water lubrication, and the sliding speed was 0.5 m / s. The specific wear amount of the plate-like test piece and the ball-like test piece was measured according to the test method.

Table 1 shows the measurement results of the specific wear amount of the plate-like test piece (own material) and the ball-like test piece (counter material) under non-lubricated and water-lubricated conditions in the air.
Table 1 also shows the blending amount, bulk density, apparent porosity, relative density, bending strength, and Vickers hardness of the carbon powder in each sintered body.
The bending strength is measured according to JIS R1601 (1995), and the Vickers hardness is according to JIS R1610 (2003). Examples 1 to 4, Examples 1 and 4 having high hardness are tests of 98.07N. The measurement was performed with a force, and Comparative Examples 2 and 3 having a low hardness were measured with a test force of 9.807N.

From Table 1, the silicon carbide composite sintered bodies (Examples 1 to 4) of the present invention are both mechanically higher in bending strength and Vickers hardness than the conventional silicon carbide composite sintered body (Comparative Example 3). In addition to excellent characteristics, the amount of specific wear between the self-material and the counterpart material is particularly low under no lubrication in the atmosphere.
The silicon carbide composite sintered body (Comparative Example 1) in which the blending amount of the carbon powder is less than 3 parts by mass and the silicon carbide sintered body not containing the carbon powder (Comparative Example 4) are dense and excellent in mechanical properties. There is a lot of specific wear of the material and the mating material.
Moreover, the silicon carbide composite sintered body (Comparative Example 2) in which the blending amount of the carbon powder is more than 17 parts by mass is low in both bending strength and Vickers hardness, and the specific material and the counterpart material have a large amount of specific wear.
As described above, according to the present example, a silicon carbide composite sintered body excellent in slidability can be obtained that can reduce the aggressiveness of the counterpart material under water lubrication and non-lubrication in the atmosphere and the specific wear amount of the self material. It is clear.

(Comparative Example 5)
In the degreasing step of the method for producing the silicon carbide composite sintered body described in the examples, the molded body was heated to 550 ° C. and heated for 1 hour in a 26 Pa air atmosphere at a heating rate of 300 ° C./hour. A silicon carbide composite sintered body of Comparative Example 5 was obtained in the same manner as in Example 2 except that the degreased molded body was obtained by cooling to room temperature.

(Comparative Example 6)
In the degreasing step, the molded body was heated to 1150 ° C. at a heating rate of 300 ° C./hour in an air atmosphere of 26 Pa and held for 1 hour, and then cooled to room temperature to obtain a degreased molded body. In the same manner as in Example 2, a silicon carbide composite sintered body of Comparative Example 6 was obtained.

(Comparative Example 7)
The degreased compact pressed in the pressurizing step was heated and heated to 1500 ° C at a heating rate of 300 ° C / hour in an air atmosphere under a reduced pressure of 26 Pa in the sintering step, and then 0.1 MPa at 1500 ° C. After substituting for the argon atmosphere, a silicon carbide composite sintered body of Comparative Example 7 was obtained in the same manner as in Example 2 except that atmospheric pressure sintering was performed at 1750 ° C. for 2 hours.

(Comparative Example 8)
The degreased compact pressed in the pressurizing step was heated and heated to 1500 ° C at a heating rate of 300 ° C / hour in an air atmosphere under a reduced pressure of 26 Pa in the sintering step, and then 0.1 MPa at 1500 ° C. The silicon carbide composite sintered body of Comparative Example 8 was obtained in the same manner as in Example 2 except that the atmospheric pressure sintering was performed at 2250 ° C. for 2 hours.

(Comparative Example 9)
Comparative Example 9 was performed in the same manner as in Example 2 except that the molded body obtained in the molding process was pressurized again by a cold isostatic pressing method at 150 MPa without performing the degreasing process (pressurizing process). A silicon carbide composite sintered body was obtained.

(Comparative Example 10)
The degreased molded body obtained in the degreasing step was heated and heated to 1500 ° C. at a rate of temperature increase of 300 ° C./hour in an air atmosphere under a reduced pressure of 26 Pa without performing the pressurizing step, and then at 0. After substituting with an argon atmosphere of 1 MPa, a silicon carbide composite sintered body of Comparative Example 10 was obtained in the same manner as in Example 2 except that sintering was performed at 2050 ° C. for 2 hours under normal pressure (sintering step).
The bulk density, the apparent porosity, the relative density, the bending strength (JIS R1601 (1995)) and the Vickers hardness (JIS R1610 (JIS R1610)) of each of the silicon carbide composite sintered bodies of Comparative Examples 5 to 10 and Example 2 used as the reference sample. 2003)) is shown in Table 2.

From Table 2, in Comparative Example 5 in which the degreasing temperature is lower than 600 ° C. and in Comparative Example 9 in which the degreasing process was not performed, sintering was insufficient due to gas generated due to insufficient decomposition of the organic matter, and thus the obtained composite sintering Both body density and hardness are lower than in Example 2.
Further, in Comparative Example 6 where the degreasing temperature is higher than 1100 ° C., the carbon powder is decomposed and burnt down in the degreasing step, so that the density and hardness of the obtained composite sintered body are lower than in Example 2.
In Comparative Example 7 where the sintering temperature is lower than 1800 ° C., since the sintering is insufficient, the density and hardness of the obtained composite sintered body are both significantly lower than in Example 2 and the comparison is higher than 2200 ° C. In Example 8, the density and hardness of the obtained composite sintered body are both lower than in Example 2 due to abnormal grain growth.
Moreover, in Comparative Example 10 in which the pressurizing step was not performed, densification of the degreased molded body was insufficient, and thus the density and hardness of the obtained composite sintered body were lower than in Example 2.
As described above, according to this example, it is clear that a high-density silicon carbide composite sintered body can be obtained by atmospheric pressure sintering.

  A silicon carbide composite sintered body in which carbon powder is dispersed in silicon carbide and a method for producing the same, and using a carbon powder made of porous carbonized powder having at least a part of the surface coated with a carbonized coating Cushioning performance against the load stress of the oil is demonstrated, and the loadability of the lubricant is improved under the lubrication conditions such as water and oil. A silicon carbide composite sintered body excellent in slidability under non-lubrication can be provided, and the degreased molded body is sintered after being pressed by a cold isostatic pressing method (CIP). Thus, a silicon carbide composite sintered body capable of mass-producing a high-density composite sintered body by atmospheric pressure sintering without requiring large-scale equipment such as hot isostatic pressing (HIP) or hot pressing (HP). The manufacturing method of can be provided.

Scanning electron microscope (SEM) photo of carbon powder Scanning electron microscope (SEM) photograph of a magnified surface of carbon powder Scanning electron microscope (SEM) photograph of the cut surface of the silicon carbide composite sintered body of Example 2 Scanning electron microscope (SEM) photograph in which the surface of the carbon powder of the cut surface of the silicon carbide composite sintered body of Example 2 was enlarged.

Claims (9)

A silicon carbide composite sintered body in which carbon powder is dispersed in silicon carbide,
The carbon powder is a porous carbonized powder in which at least a part of the surface is coated with a carbonized film, and the blending amount of the carbon powder is 3 to 17 parts by mass with respect to 100 parts by mass of the silicon carbide. A silicon carbide composite sintered body characterized. The silicon carbide composite sintered body according to claim 1,
An average thickness of the carbonized coating is 1/20 to 1/5 of an average particle diameter of the carbon powder. The silicon carbide composite sintered body according to claim 1 or 2,
The porous silicon carbide powder has pores having an average diameter of 0.5 to 5 μm. A silicon carbide composite sintered body according to any one of claims 1 to 3,
The carbon powder is a granulated product obtained by kneading a moss and a synthetic resin such as a thermosetting resin or a thermoplastic resin in an inert gas atmosphere under normal pressure or in an air atmosphere under reduced pressure. A silicon carbide composite sintered body, which is a carbide obtained by carbonizing at a temperature of 700 to 1100 ° C. A method for producing a silicon carbide composite sintered body in which carbon powder is dispersed in silicon carbide,
A mixing step of obtaining a mixed powder by mixing a carbon powder composed of a porous carbonized powder having at least a part of the surface coated with a carbonized film and a silicon carbide powder, and a forming step of obtaining a molded body by forming the mixed powder. A degreasing step of heating and degreasing the molded body at a temperature of 600 to 1100 ° C. to obtain a degreased molded body, a pressurizing step of pressurizing the degreased molded body by a cold isostatic pressing method, and the pressurization And a sintering step of obtaining a sintered body by heating and sintering the degreased molded body pressed in the step at 1800 to 2200 ° C. A method for producing a silicon carbide composite sintered body according to claim 5,
The compounding quantity of the said carbon powder is 3-17 mass parts with respect to 100 mass parts of said silicon carbide, The manufacturing method of the silicon carbide compound sintered compact characterized by the above-mentioned. A method for producing a silicon carbide composite sintered body according to claim 5 or 6,
An average thickness of the carbonized coating is 1/20 to 1/5 of an average particle diameter of the carbon powder. A method for producing a silicon carbide composite sintered body according to any one of claims 5 to 7,
The method for producing a silicon carbide composite sintered body, wherein the porous carbonized powder has pores having an average diameter of 0.5 to 5 μm. A method for producing a silicon carbide composite sintered body according to any one of claims 5 to 8,
The carbon powder is a granulated product obtained by kneading a moss and a synthetic resin such as a thermosetting resin or a thermoplastic resin in an inert gas atmosphere under normal pressure or in an air atmosphere under reduced pressure. A method for producing a silicon carbide composite sintered body, which is a carbide obtained by carbonizing at a temperature of 700 to 1100 ° C.