JP2001139376A - Silicon carbide sintered compact, and mechanical seal and segment seal using the silicon carbide sintered compact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicon carbide sintered compact which is capable of exhibiting an excellent sliding characteristic as well as a mechanical seal and segment seal using the sintered compact as sliding members. SOLUTION: B4C powder of 0.18 pts.wt., a water-soluble phenolic resin of 4.8 pts.wt., polyvinyl alcohol of 2.5 pts.wt. and carbon beads 2 of 30 μm in an average particle size internally having hollows of 10 pts.wt. and ion exchange water are added, as sintering assistants, to 100 pts.wt. α type silicon carbide powder of 0.4 μm in an average particle size to prepare a slurry of 40% concentration. The slurry is mixed for one hour in a vibration mill and is granulated by a spray drier. The granules are packed into molds and is pressure molded under pressure of 150 MPa. The moldings are shaped to a prescribed shape by mechanical working and the moldings are sintered in an argon atmosphere of 2,100 deg.C. Self-lubricity may be obtained by the presence of the carbon beads 2. The hollows 3 of the carbon beads 2 act as liquid traps for a lubricating liquid thereby improving the lubricating characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon carbide sintered body used for a sliding member such as a mechanical seal for sealing a rotating part of a pump or a compressor or a segment seal for sealing a rotating part of an aircraft jet engine or the like. The present invention relates to a mechanical seal using the silicon carbide sintered body as a sliding material and a segment seal using the silicon carbide body as a sliding material.

[0002]

2. Description of the Related Art Silicon carbide sintered bodies are used as sliding members such as mechanical seals and segment seals.
It is a material generally known together with a carbon material, a cemented carbide and an alumina sintered body, and is often used in combination with a carbon material or a combination of silicon carbide sintered bodies.

[0003] A silicon carbide sintered body is an excellent material having high hardness and high corrosion resistance, but since it is a smooth material having no self-lubricating property, blisters are generated on the mating material when combined with a carbon material. Or a combination of the silicon carbide sintered bodies may cause sticking.

[0004] In order to solve such a problem, a reaction sintered type silicon carbide sintered body in which silicon carbide particles are filled with metallic silicon is used as a material for imparting self-lubricating properties to a silicon carbide sintered body. A carbon-dispersed silicon carbide sintered body in which an appropriate amount of carbon particles are dispersed in a silicon carbide sintered body in an appropriate amount, and pores of an appropriate size that reduce the denseness of the silicon carbide sintered body are appropriately formed. There is a pore-dispersed silicon carbide sintered body in which the amount is dispersed.

[0005] Of these materials, the material is generally used because the corrosion resistance is greatly degraded depending on the use environment due to the presence of metallic silicon.

[0006] With respect to the sliding performance, it is advantageous to use a material whose pores act as a pool of lubricating liquid and have a great effect of reducing the heat generated by sliding. However, the volume of the pores occupying in the silicon carbide sintered body is advantageous. When the rate is increased, the denseness of silicon carbide is impaired, and the strength is reduced. Also, if the mating material is a metal substrate surface with a coating,
The edge around the pores causes the coating film of the mating material to be worn or peeled.

The present invention has solved the above-mentioned problems of the prior art, and can exhibit excellent sliding characteristics. In particular, the present invention is excellent even in an environment where it is temporarily dry. It can exhibit sliding characteristics, does not cause blistering or sticking to the mating material, does not significantly reduce the strength, and has a mating material made of metal. It is an object of the present invention to provide a silicon carbide sintered body which does not wear or peel off a coating film of a mating material even if a coating is applied to a substrate surface, and has excellent workability. It is an object of the present invention to provide a mechanical seal using the silicon carbide sintered body and a segment seal using the silicon carbide sintered body.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides carbon beads having an average particle diameter of 10 to 100 .mu.m having a hollow inside of the particles by 4 to 30% by volume.
Means of inclusion are adopted. Further, in a mechanical seal adapted to seal a rotating part by sliding contact between the stationary ring and the rotating ring, at least one of the stationary ring and the rotating ring has a hollow inside the particle. It employs means formed of a silicon carbide sintered body containing 4 to 30% by volume of carbon beads having an average particle diameter of 10 to 100 μm. Furthermore, in a mechanical seal adapted to seal a rotating part by sliding contact between a stationary ring and a rotating ring, one of the stationary ring and the rotating ring may be an average having a hollow inside a particle. It employs a means of forming a silicon carbide sintered body containing 4 to 30% by volume of carbon beads having a particle diameter of 10 to 100 μm, and forming one of the other surfaces by coating a metal substrate surface. is there. Further, in a segment seal in which a rotating portion is sealed by sliding contact between a seal ring and a runner, the seal ring may be formed of carbon beads having a hollow inside the particle and having an average particle diameter of 10 to 100 μm. Is formed from a silicon carbide sintered body containing 4 to 30% by volume, and the runner is formed by coating the surface of a metal base material. The seal ring employs a means that is divided into a plurality in the circumferential direction.

[0009]

According to the present invention, when the silicon carbide sintered body according to the present invention is used as a sliding member, the self-lubricating property can be obtained due to the presence of the carbon beads, and the carbon beads can be obtained. The pores formed by the internal hollows function as a pool of lubricating liquid.
Also, when the silicon carbide sintered body according to the present invention is used for at least one of the stationary ring and the rotating ring of the mechanical seal according to the present invention, the self-lubricating property is obtained by the presence of the carbon beads, The pores formed by the internal hollow act as a liquid pool for the lubricating liquid. Furthermore, even when using the silicon carbide sintered body according to the present invention for either the stationary ring or the rotating ring of the mechanical seal according to the present invention, and using the one coated with the metal base material surface on the other, The self-lubricating property is obtained by the presence of the carbon beads, and the pores formed by the hollow inside of the carbon beads act as a pool of lubricating liquid. Also, when the silicon carbide sintered body according to the present invention is used for the seal ring of the segment seal according to the present invention, and a runner coated with a metal base material surface is used, the self-lubricating property is maintained due to the presence of the carbon beads. While being obtained, the pores formed by the hollow inside of the carbon beads act as a liquid pool for the lubricating liquid.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of repeated studies, the inventors of the present invention have found that a silicon carbide sintered body containing carbon beads having a hollow interior and a spherical shape is the most influential for achieving the above object. I found something.

That is, it has been found that the self-lubricating property is imparted by the presence of the carbon beads, and that the hollow pores inside the carbon beads act as a pool of lubricating liquid. By using a silicon carbide sintered body having such characteristics as a sliding member, excellent sliding characteristics can be exhibited, and blisters are generated in a mating material or sticking is caused. And the strength is not greatly reduced. Further, even if the mating material has a coating on the surface of the metal substrate, the coating film of the mating material is worn out or peeled off. I found that there was no such thing.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of a silicon carbide sintered body according to the present invention. This silicon carbide sintered body 1 has an average particle diameter of 10 to 10 having a hollow 3 inside the particle.
It contains 4 to 30% by volume of 100 μm carbon beads 2.

In the carbon beads 2, ring-shaped particle shells 4 are evenly dispersed on the surface of the silicon carbide sintered body 1, and the hollows 3 inside the particles are exposed to the surface to form pores 3 at the portions. It has become.

Since the size of the pores 3 does not exceed the size of the carbon beads 2 itself, it can be controlled by the size of the particles of the carbon beads 2 to be blended.

The size of the particles of the carbon beads 2 is suitably from 10 to 100 μm in average particle size. When the average particle diameter is 10 μm or less, the voids 3 inside the particles are not sufficiently exposed on the surface and are surrounded by the ring-shaped particle outer shell 4.
Cannot be formed. When the average particle diameter is 10 μm or more, the hollows 3 inside the particles are sufficiently exposed on the surface, and the pores 3 surrounded by the ring-shaped particle outer shell 4 can be formed. However, when the average particle diameter is 100 μm or more, the average pore diameter becomes 80 μm or more, which may cause liquid leakage or the like.

The amount of the pores 3 depends on the carbon beads 2 to be mixed.
Can be controlled by the amount of Carbon beads 2
Volume fraction in silicon carbide sintered body 1 is 4 to 30% by volume
Is suitable, and the porosity is 2 to 15% by volume.
If the porosity is 2% by volume or less, a sufficient lubricating effect due to the liquid pool in the pores 3 cannot be obtained. If it is 15% by volume or more, the content of the carbon beads 2 is too large, and the strength is reduced.

Next, a method of manufacturing a silicon carbide sintered body according to the present invention will be described. The raw material of the silicon carbide sintered body 1 of the present invention may be either α-type or β-type. As the sintering aid, both known alumina type and boron / carbon type can be used.

Then, predetermined carbon beads 2 are added to the α-type or β-type silicon carbide powder together with a sintering aid, a forming aid, and a granulating binder, mixed, and the resulting slurry is granulated by spray drying. I do. As a method of uniformly dispersing the carbon beads 2, a ball mill mixing of the raw material mixture with an aqueous medium, which is generally widely performed, is appropriate.

Then, it is molded by a general molding method such as a rubber press or a mold press, and heated in a vacuum or an inert gas atmosphere to form a silicon carbide sintered body 1 containing a predetermined amount of carbon beads 2. Similarly, a silicon carbide sintered body 1 containing a predetermined amount of carbon beads 2 can be formed by a hot press method in which molding and sintering are performed in one step.

Next, an embodiment of the silicon carbide sintered body according to the present invention will be described. <Example 1> α-type carbon silicon powder 1 having an average particle diameter of 0.4 µm
0.1 parts by weight of B ₄ C powder as a sintering aid per 100 parts by weight.
8 parts by weight, 4.8 parts by weight of a water-soluble phenol resin, 2.5 parts by weight of polyvinyl alcohol, and 3
Carbon beads 2 having an average particle diameter of 30 μm having
A part by weight and ion-exchanged water were added to form a 40% concentration slurry, mixed for 1 hour in a vibration mill, and granulated with a spray drier. The granules are filled in a metal mold and 15
It was pressed under a pressure of 0 MPa, formed into a test piece shape by machining, and then sintered in an argon atmosphere at 2100 ° C. Table 1 shows the characteristics of the obtained test pieces. FIG. 1 shows a schematic view of the polished surface of the test piece viewed with an optical microscope.

Example 2 100 parts by weight of α-type silicon carbide powder having an average particle diameter of 0.4 μm was mixed with B ₄ C as a sintering aid.
0.18 parts by weight of powder and 4.8 of water-soluble phenol resin
Parts by weight, 2.5 parts by weight of polyvinyl alcohol, and commercially available carbon beads 2 having an average particle diameter of 100 μm and having hollows 3 therein, 22 parts by weight and ion-exchanged water were added to form a 40% -concentration slurry, which was mixed in a vibration mill for 1 hour. And granulated with a spray dryer. The granules were filled in a metal mold, pressed under a pressure of 150 MPa, formed into a test piece shape by machining, and then sintered at 2100 ° C. in an argon atmosphere. Table 1 shows the characteristics of the obtained test pieces.

Example 3 100 parts by weight of α-type silicon carbide powder having an average particle diameter of 0.4 μm was mixed with B ₄ C as a sintering aid.
0.18 parts by weight of powder and 4.8 of water-soluble phenol resin
Parts by weight, 2.5 parts by weight of polyvinyl alcohol, and a commercially available carbon bead 2 having an average particle diameter of 10 μm and having hollow 3 therein, both parts of which are mixed with ion-exchanged water to form a 40% -concentration slurry, which is placed in a vibration mill for 1 hour. They were mixed and granulated with a spray drier. The granules were filled in a metal mold, pressed under a pressure of 150 MPa, formed into a test piece shape by machining, and then sintered at 2100 ° C. in an argon atmosphere. Table 1 shows the characteristics of the obtained test pieces.

<Comparative Example 1> B ₄ C was added as a sintering aid to 100 parts by weight of α-type silicon carbide powder having an average particle diameter of 0.4 μm.
0.18 parts by weight of powder and 4.8 of water-soluble phenol resin
Parts by weight, 2.5 parts by weight of polyvinyl alcohol and ion-exchanged water to form a slurry having a concentration of 40%.
h and granulated with a spray drier. The granules were filled in a metal mold, pressed under a pressure of 150 MPa, formed into a test piece shape by machining,
Sintering was performed in an argon atmosphere at 0 ° C. Table 1 shows the characteristics of the obtained test pieces.

Comparative Example 2 B ₄ C was used as a sintering aid for 100 parts by weight of α-type silicon carbide powder having an average particle diameter of 0.4 μm.
0.18 parts by weight of powder and 4.8 of water-soluble phenol resin
Parts by weight, 2.5 parts by weight of polyvinyl alcohol, and 30 parts by weight of commercially available hollow carbon beads having an average particle diameter of 100 μm and ion-exchanged water to form a 40% -concentration slurry, and mixed for 1 hour in a vibration mill, It granulated with a spray drier. The granules were filled in a metal mold, pressed under a pressure of 150 MPa, formed into a test piece shape by machining, and then sintered at 2100 ° C. in an argon atmosphere. Table 1 shows the characteristics of the obtained test pieces.

Comparative Example 3 B ₄ C was used as a sintering aid for 100 parts by weight of α-type silicon carbide powder having an average particle diameter of 0.4 μm.
0.18 parts by weight of powder and 4.8 of water-soluble phenol resin
Parts by weight, 2.5 parts by weight of polyvinyl alcohol, and 1.5 parts by weight of commercially available hollow carbon beads having an average particle diameter of 10 μm and ion-exchanged water to obtain a 40% -concentration slurry, and mixed in a vibration mill for 1 hour. And granulated with a spray dryer. The granules were filled in a metal mold, pressed under a pressure of 150 MPa, formed into a test piece shape by machining, and then sintered at 2100 ° C. in an argon atmosphere. Table 1 shows the characteristics of the obtained test pieces.

[0026]

[Table 1]

The test pieces prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were used as rotating rings 5 for the seal rotation test, and the fixed rings 6 were carbonized to the test pieces of Example 1, Comparative Example 1 and the AMS6322 base material. 100 ° C using chrome coating
Shimizu, liquid pressure 0.7MPa, 3600rpm 10
A 0 h test was conducted to examine the wear amount and appearance of the stationary ring 6. The shape of each test piece is shown in FIGS. 2 and 3, and the test results are shown in Table 2.

[0028]

[Table 2]

From the above test results, it can be seen that the silicon carbide sintered body 1 of the present invention can exhibit excellent sliding characteristics, and exhibit excellent sliding characteristics even in a temporarily dry environment. No blistering or sticking occurs in the mating material, the strength does not significantly decrease, and the mating material is a metal base material (AMS6322 base material). It can be seen that even if a coating (chromium carbide coating) is applied to the coating material, the coating film of the mating material does not wear or peel off.

FIG. 4 shows an embodiment of the mechanical seal according to the present invention.
0 is an annular fixed ring 12 attached to the housing 11 side and having a sliding surface 13 at one end in the axial direction;
An annular rotating ring 15 attached to the rotating shaft 14 and having a sliding surface 16 at one end in the axial direction and a sliding surface 13 of the fixed ring 12 in sliding contact with each other; The ring 15 is fixed to the fixed ring 12 by the cooperation of the compression ring 17 and the compression spring 18.
In such a direction as to be pressed.

In this case, at least one of the stationary ring 12 and the rotating ring 15 has a silicon carbide sintered body having the same configuration as the silicon carbide sintered body 1 according to the present invention, that is, has a hollow inside the particle. It is formed of a silicon carbide sintered body containing 4 to 30% by volume of carbon beads having an average particle diameter of 10 to 100 μm. (See FIG. 1).

When the rotating shaft 14 rotates, the stationary ring 1
When the sliding surfaces 13 and 16 of the rotating ring 15 and the rotating ring 15 are in sliding contact with each other, the space between the rotating shaft 14 and the housing 11 is sealed.

In the mechanical seal 10 according to this embodiment configured as described above, at least one of the stationary ring 12 and the rotating ring 15 has a hollow inside the particle and carbon beads having an average particle diameter of 10 to 100 μm. 4
Since it is formed of a silicon carbide sintered body containing up to 30% by volume, self-lubricating properties can be obtained due to the presence of carbon beads, and hollow pores of the carbon beads act as a pool of lubricating liquid. . Therefore, excellent sliding characteristics can be exhibited at the time of sliding contact between the stationary ring 12 and the rotating ring 15, so that excellent sliding characteristics can be exhibited even in an environment in which the ring is temporarily dry. A blister may be generated on the ring 12 or the rotating ring 15 or the fixed ring 1
2 and the rotating ring 15 do not stick to each other. In addition, since the fixed ring 12 or the rotating ring 15 formed of the silicon carbide sintered body does not greatly decrease in strength, stable sliding characteristics can be obtained for a long period of time.

In the above description, the fixed ring 12
Alternatively, at least one of the rotating rings 15 is formed of a silicon carbide sintered body containing 4 to 30% by volume of carbon beads having an average particle diameter of 10 to 100 μm having a hollow inside the particles. 15 is formed of a silicon carbide sintered body containing 4 to 30% by volume of carbon beads having an average particle diameter of 10 to 100 μm having a hollow inside the particle, and the other is formed of a metal substrate (based on AMS6322). The same effect can of course be obtained when the material is formed by applying a coating (chromium carbide coating) to the material). The coating film of the mating material is not worn or peeled off by the edges around the pores of the sliding surfaces 13 and 16 of the fixed ring 12 or the rotating ring 15. Good sliding characteristics can be obtained.

FIG. 5 shows an embodiment of a segment seal according to the present invention. This segment seal 20 is attached to a rotating shaft 21 and has a cylindrical shape having a sliding surface 23 on the outer peripheral surface. And a sliding surface 26 attached to the housing 24 side and having a sliding surface 26 on the inner peripheral surface thereof in sliding contact with the sliding surface 23 of the runner 22 and divided into a plurality in the circumferential direction. The compression spring 27 and the compression ring 28 cooperate to press the seal ring 25 in the axial direction, and the extension spring 29 presses the seal ring 25 in the radial direction. It is what was constituted.

In this case, the seal ring 25 is made of a silicon carbide sintered body having the same structure as the above-described silicon carbide sintered body of the present invention, that is, having an average particle diameter of 1 having a hollow inside the particle.
It is formed of a silicon carbide sintered body containing 4 to 30% by volume of carbon beads of 0 to 100 μm. (See FIG. 1).

When the rotating shaft 21 rotates, the sliding surface 26 of the seal ring 25 and the sliding surface 23 of the runner 22 make sliding contact with each other, so that a seal is formed between the rotating shaft 21 and the housing 24. Is what is done.

In the segment seal 20 according to this embodiment configured as described above, the seal ring 25
Has an average particle diameter of 10 to 100 μm having a hollow inside the particle
Is formed of a silicon carbide sintered body containing 4 to 30% by volume of carbon beads, self-lubricating property is obtained by the presence of the carbon beads, and hollow pores of the carbon beads serve as a pool of lubricating liquid. Will work. Therefore, excellent sliding characteristics can be exhibited at the time of sliding contact between the seal ring 25 and the runner 22, so that excellent sliding characteristics can be exhibited even in a temporarily dry environment. The seal ring 25 and the runner 22 do not stick to each other. In addition, since the seal ring 25 formed of the silicon carbide sintered body does not greatly decrease in strength, stable sliding characteristics can be obtained for a long period of time. Furthermore, the coating film of the runner 22 is not worn or peeled off by the edges around the pores of the sliding surface 26 of the seal ring 25 formed of the silicon carbide sintered body, and the Good sliding characteristics can be obtained.

Next, an embodiment of the segment seal according to the present invention will be described. <Example 5> A ring-shaped sintered body was prepared by the same compounding method as in Example 1 described above, and a one-ring eight-part seal ring having an inner diameter of 130 mm was manufactured by grinding. It could be processed like a conventional carbon ring. The seal ring was combined with a runner having a sliding surface of an AMS5662 metal substrate coated with chromium carbide to form a segment seal.

A performance test was performed using the segment seal having the above-described configuration as an oil seal for a bearing chamber for a gas generator. FIG. 6 shows the structure of the gas generator bearing chamber.

Here, 30 is a segment seal, 31 is a seal ring, 32 is a runner, 33 is an extension spring, 34 is a compression spring,
5 is a compression ring and 36 is a bearing.

The interior of the chamber B is an oil mist atmosphere for bearing lubrication, and a segment seal 30 is attached to seal it. The pressure in the chambers A and B fluctuates depending on the operation state of the gas generator, and the differential pressure (P (A) -P (B)) is -0.005 to 0.8MP.
a. When the differential pressure is small, the oil leaks to the seal portion and wets the seal ring 31. When the differential pressure increases, air leaks from the gap between the seal ring 31 and the runner 32 to prevent oil from leaking. By using a silicon carbide sintered body containing carbon beads for the seal ring 31, oil leaking at a low differential pressure is retained in pores in the carbon beads on the surface of the seal ring 31, and this oil is lubricated at a high differential pressure. It is expected to act as an oil. Since the runner 32 rotating at a high speed is subjected to centrifugal force, a highly reliable metal material coated on the surface is used. If the seal ring 31 is a silicon carbide sintered body containing carbon beads, a stable operation is expected without damaging the coating film of the runner 32. The test conditions were: peripheral speed: 0 to 150 m / s; air differential pressure: -0.005 to 0.8 MPa; The test result shows that no oil leakage to room A was observed.
The air leakage amount at 0.8 MPa was an excellent value of 40 NI / min. No damage was found on the runner 32 after the test.

[0043]

According to the present invention, when the silicon carbide sintered body is used for a sliding member,
The self-lubricating property is obtained by the presence of the carbon beads, and the hollow pores inside the carbon beads act as a pool of lubricating liquid. Therefore, excellent sliding characteristics can be exhibited, and even in a temporarily dry environment, excellent sliding characteristics can be exhibited, and blisters are generated on the mating material or sticking is caused. Nothing is gone. Further, the strength does not significantly decrease. Furthermore, even if the mating material is a metal substrate coated, the coating film of the mating material will not be worn or peeled off.

According to the second aspect of the present invention, at least one of the stationary ring and the rotating ring of the mechanical seal has the same structure as the silicon carbide sintered body according to the first aspect. Since it is formed by a body, the self-lubricating property is obtained by the presence of the carbon beads, and the hollow pores inside the carbon beads act as a pool of lubricating liquid. Therefore, since excellent sliding characteristics can be exhibited at the time of sliding contact between the fixed ring and the rotating ring, it is possible to exhibit excellent sliding characteristics even in a temporarily dry environment. It is possible to prevent the occurrence of blisters on the rotating ring and the mutual fixing of the fixed ring and the rotating ring to each other. In addition, since the fixed ring or the rotating ring formed of the silicon carbide sintered body does not greatly decrease in strength, stable sliding characteristics can be obtained for a long period of time.

Further, the configuration according to the third aspect provides the same effect as that of the second aspect, and furthermore, the surroundings of the pores around the sliding surface of the stationary ring or the rotating ring formed of the silicon carbide sintered body. The edge does not cause the coating film of the mating material to be worn or peeled off, and even with such a combination, good sliding characteristics can be obtained for a long period of time.

According to the fourth and fifth aspects, the seal ring of the segment seal is formed of a silicon carbide sintered body having the same configuration as the silicon carbide sintered body of the first aspect. Therefore, the self-lubricating property is obtained by the presence of the carbon beads, and the hollow pores inside the carbon beads act as a liquid pool of the lubricating liquid. Therefore, excellent sliding characteristics can be exhibited at the time of sliding contact between the seal ring and the runner, so that excellent sliding characteristics can be exhibited even in a temporarily dry environment, and the seal ring or runner can be exhibited. This prevents the occurrence of blisters and the fact that the seal ring and the runner are fixed to each other. In addition, since the seal ring formed of the silicon carbide sintered body does not significantly decrease in strength, stable sliding characteristics can be obtained for a long period of time. Furthermore, the edge around the pores of the sliding surface of the seal ring formed of the silicon carbide sintered body does not cause the coating film of the runner to be worn or peeled off, and a good sliding performance over a long period of time. Dynamic characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one embodiment of a silicon carbide sintered body according to the present invention, and is a schematic diagram in which a polishing surface is viewed with an optical microscope.

FIG. 2 is a schematic view of a rotating ring as a test piece used in a seal rotation test, wherein (a) is a plan view and (b) is AA.
It is a line sectional view.

3A and 3B are schematic views of a fixed ring as a test piece used in a seal rotation test, wherein FIG. 3A is a plan view and FIG.
It is a line sectional view.

FIG. 4 is a schematic view showing an embodiment of a mechanical seal according to the present invention.

FIG. 5 is a schematic view showing an embodiment of a segment seal according to the present invention.

FIG. 6 is a schematic view showing a structure of a gas generator bearing chamber used in a performance test of a segment seal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Sintered silicon carbide 2 ... Carbon beads 3 ... Hollow (pore) 4 ... Particle shell 5, 15 ... Rotating ring 6, 12 ... Fixed ring 10 ... Mechanical seal 11, 24 ... Housing 13, 16, 23, 26 ... Sliding surface 14, 21 ... Rotating shaft 17, 28, 35 ... Compression ring 18, 27, 34 ... Compression spring 20, 30 ... Segment seal 22, 32 ... Runner 25, 31 Seal ring 29, 33 Extension spring 36 Bearing

Claims (5)

[Claims] 1. An average particle diameter of 10 having a hollow inside the particle.
A silicon carbide sintered body containing 4 to 30% by volume of carbon beads having a size of 100 to 100 μm. 2. A mechanical seal in which a rotating part is sealed by sliding contact between a stationary ring and a rotating ring, wherein at least one of the stationary ring and the rotating ring is placed inside a particle. A mechanical seal formed of a silicon carbide sintered body containing 4 to 30% by volume of hollow carbon beads having an average particle diameter of 10 to 100 μm. 3. A mechanical seal wherein a rotating part is sealed by sliding contact between a stationary ring and a rotating ring, wherein one of the stationary ring and the rotating ring is hollow inside the particle. Having an average particle diameter of 10 to 10
A mechanical seal comprising: a silicon carbide sintered body containing 4 to 30% by volume of 0 μm carbon beads; and the other being formed by coating a metal substrate surface. 4. A segment seal in which a rotating part is sealed by sliding contact between a seal ring and a runner, wherein the seal ring is formed by:
It was formed of a silicon carbide sintered body containing 4 to 30% by volume of carbon beads having an average particle diameter of 10 to 100 μm having a hollow inside the particles, and the runner was formed by coating a metal substrate surface. A segment seal characterized in that: 5. The segment seal according to claim 4, wherein the seal ring is divided into a plurality in the circumferential direction.