JP3035720B2 - Method for producing ceramic-carbon composite material and sliding component - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a ceramic used in the sliding structural member or the like - to a method of manufacturing carbon-based composite materials and the sliding component using the same.

[0002]

2. Description of the Related Art Since ceramics have better heat resistance, strength, hardness and corrosion resistance than metals, their use as structural members has been actively studied in recent years. In particular, among them, silicon carbide ceramics
Due to its excellent strength, hardness, and corrosion resistance, it has been partially used as a sliding member such as a mechanical seal and a bearing. However, its use range has been limited due to poor sliding characteristics in a dry atmosphere and low thermal shock resistance.

As a means for solving the sliding property, which is one of these problems, a method of compounding a solid lubricant such as carbon or graphite in silicon carbide is disclosed in Japanese Patent Application Laid-Open No. 63-260861, entitled "SiC- Graphite-based self-lubricating ceramics "
And a method of combining granulated graphite particles with "self-lubricating ceramic composite material and a method for producing the same" in JP-A-63-265850;
A method of blending self-sintering spherical carbonaceous fine particles into a "powder composition for producing a silicon carbide composite material, a method for producing a carbon-silicon carbide composite material, and a carbon-silicon carbide composite material" is disclosed.

[0004] In any case, however, the friction coefficient at the time of sliding decreases due to the incorporation of carbon and graphite particles, but the density does not become high, the strength decreases, the inherent properties of ceramics are impaired, and the durability is lowered. The problem of inferiority has been pointed out. Japanese Patent Application Laid-Open No. 1-320254 discloses a method of optimizing the degree of graphitization of composite carbon by X-ray diffraction in "ceramic-carbon composite material and method for producing the same". Although it is excellent, it does not optimize the existing state of the composite carbon and the carbon source, has poor thermal shock resistance, and is not preferable in terms of industrial production because it is manufactured by a complicated method of firing under pressure. The problem has been pointed out.

An object of the present invention, strength, sliding properties, thermal shock resistance excellent ceramics - to provide a method of producing a carbon-based composite materials and the sliding component using the same.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that ceramics
In the carbon-based composite material, it has been found that excellent effects can be obtained by setting the domain diameter and the domain area ratio of carbon to specific ranges, and have completed the present invention. That is, the gist of the present invention is as follows: (1) Ceramic powder (excluding silicon carbide powder )
A) a condensed polycyclic aromatic compound and / or a polycondensed aromatic compound having an H / C of 0.2 to 2.0, an N and S content of 2% or less, respectively, and an average molecular weight of 100 to 2000; The sintering aid powder is mixed according to
(C) a method for producing a ceramic-carbon composite material, which is calcined at a temperature of ℃, then granulated, and then fired; and (2) the mechanical element has a movable part and is in temporary or constant contact. And a sliding component that relatively slides, wherein at least the sliding surface is made of a ceramic-carbon composite material obtained by the manufacturing method described in (1) above. About.

In the ceramic-carbon composite material of the present invention, the domain diameter of carbon means the size of carbon particles or an aggregate thereof distributed in a ceramic matrix, and is a scanning type of a mirror-finished sample. Observed by an electron microscope, the carbon domain in the obtained 100 images was analyzed by an image analyzer and calculated as an average value. Usually, it is 0.01 to 30 μm, preferably 0.05 to 20 μm. Domain diameter 0.01μm
If it is smaller than this, the sliding characteristics will not be exhibited, and if it is larger than 30 μm, the strength will decrease, which is not preferable.

The domain area ratio of carbon is also an average value of the ratio of carbon domains in the ceramic matrix similarly calculated by image analysis, and is usually 5 to 70%.
Preferably it is 7 to 60%. If it is less than 5%, the sliding characteristics will not be exhibited, and if it is more than 70%, the strength will be reduced, which is not preferable.

[0009] The total porosity means a portion other than the ceramic matrix and the carbon domain, and is an average value of the porosity similarly calculated by image analysis, and is usually 20% or less, preferably 10% or less. If it exceeds 20%, the strength is undesirably reduced.

The ceramic powder used in the present invention is A
l ₂ O ₃ , ZrO ₂ , TiO ₂ , MgO, SrO, Ni
Oxides such as O, MnO, Y ₂ O ₃ ; TiC, WC, B ₄
Carbides such as C and ZrC; Si ₃ N ₄ , AlN, BN, T
nitrides such as iN and ZrN; ZrB ₂ , CrB, TiB ₂
One or more ceramics selected from borides such as the above are preferable. As the case of two or more kinds, for example, Al ₂ O ₃ —TiO ₂ system, Al ₂ O ₃ —Si
C system, ZrO ₂ -Y ₂ O ₃ system and the like. Further, a solid solution of these compounds may be used.

[0011] The purity of the ceramic is preferably at least 90 wt%, more preferably at least 95 wt%, in order to prevent a decrease in density, deterioration of strength and fracture toughness, etc., and from the viewpoint of mechanical properties such as Young's modulus. is there. That is, if the purity is lower than 90 wt%, characteristics such as heat resistance and high hardness of the ceramics are not exhibited. From the viewpoint of sinterability, the form of the ceramic is preferably a powder having an average particle size of usually 0.05 to 5.00 µm, preferably 0.1 to 3.0 µm. If the average particle size is smaller than 0.05 μm, the powder forms an aggregate,
Does not form a uniform composite structure. The particle size is 5.00 μm.
If it exceeds m, the sinterability deteriorates, and it is difficult to obtain a high-density sintered body.

[0012] The carbon source of carbon in the composite material of the present invention is converted into carbon by heating, and has an H / C of 0.2.
It is preferable to use a condensed polycyclic aromatic compound and / or a polycondensed aromatic compound having an average molecular weight (Mw) of 100 to 2,000, an N and an S content of 2% or less at 2.0 to 2.0, respectively. Examples thereof include coal tar, pitch, phenolic resin, furan resin, and derivatives thereof, and are not particularly limited, but preferably those easily graphitizable. If the H / C and the average molecular weight deviate from this range, the dispersibility of carbon deteriorates and the strength decreases. On the other hand, if the N and S contents exceed 2%, microcracks are generated in the composite material during firing, and only low-strength materials are obtained, which is not preferable. As used herein, carbon refers to a material that exhibits a graphite peak by X-ray diffraction, and the degree of graphitization is not particularly limited, but is preferably as large as possible, and usually the (002) plane spacing by X-ray diffraction is 3.3 to 3.0.
It is in the range of 3.5 °.

The ceramic-carbon composite material of the present invention is obtained by mixing the above-mentioned ceramic powder, the above-mentioned carbon source and, if necessary, a sintering aid powder, calcining, granulating and then firing. It can be manufactured by the following. The sintering aid used here is not particularly limited, and any one can be used as long as it is usually used as a sintering aid. For example, known boron compounds, alumina, yttria and the like can be mentioned, and one or more of these are used in combination. The sintering aid in the present invention is not necessarily the case at the end hardly sintered powder, preferable results are obtained when using.

The amount of the sintering aid used in producing the ceramic-carbon composite material of the present invention is usually 0.1 to 20 watts.
t%, preferably 0.2 to 10 wt%.

The above-mentioned mixing is usually carried out by wet mixing using a ball mill, a vibration mill, a planetary mill or the like. As the solvent to be used, organic solvents such as aromatic solvents such as benzene, toluene and xylene, alcohols such as methanol and ethanol, and ketones such as methyl ethyl ketone are preferable.

The above-mentioned calcination step is carried out by subjecting the mixed mixture to a heat treatment, preferably at 300 to 600 ° C., preferably in an inert atmosphere (for example, under an atmosphere of nitrogen gas, argon gas or the like). If it is lower than 300 ° C., it is not sufficiently converted to carbon,
There are many residual volatile components and it does not densify. On the other hand, if the temperature is higher than 600 ° C., free sintering of the compounded particles occurs, and re-dispersion during spray drying becomes difficult.

In the above granulation step, granulation is performed by a known method such as spray drying. Molding can also be performed by a mold molding method, a CIP method, a slip casting method, or the like.

The above calcination step is usually carried out under a non-oxidizing atmosphere at normal pressure, for example, under an inert atmosphere (under an atmosphere of nitrogen gas, argon gas or the like) or under vacuum at 1200-2300.
It is desirable to carry out at ℃. If the sintering temperature is outside this range, the density of the sintered body is reduced, and mechanical properties such as strength and hardness are deteriorated due to the growth of ceramic particles, which is not preferable. The firing time is usually 0.5 to 8 hours. As a firing method, hot press, HI
The P method or the like may be used.

The composite material of the present invention obtained as described above has the above-described carbon domain diameter, domain area ratio, and total porosity, is excellent in strength, sliding characteristics, and has a thermal shock resistance. It has excellent resistance and is very suitable as a sliding part. That is, the ceramic-carbon-based composite material of the present invention thus obtained has a burrow strength at room temperature of 250 MPa or more, a thermal shock resistance of 250 ° C. or more,
It has excellent characteristics such as a coefficient of friction of 0.5 or less and a specific wear amount of 15 mm ² / kg or less.

The sliding component of the present invention is a sliding component in which a mechanical element has a movable part, and is temporarily or always in contact, and relatively slid. -It must be made of a carbon-based composite material. Specific examples of the sliding component include a bearing retainer, a mechanical seal, a coal slurry flow valve, a mixing faucet disk valve, and a drawing die.

[0021]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Examples 1 to 13 Carbon sources shown in Table 1, ceramic powders having an average particle size of 0.1 to 3 μm, and in Examples 1, 2, and 10, these were further mixed with a sintering aid in a wet mill using a vibration mill in a toluene atmosphere. Calcination was performed at the temperatures shown in Table 1 below. After granulation by spray drying, the mixture was molded by a mold molding method and fired under the conditions shown in Table 1. The domain diameter, domain area ratio and total porosity of carbon in the obtained composite material were observed with a scanning electron microscope on a mirror-finished sample, and the obtained 100 images were image-resolved (LUZEX-III, Nireco Co., Ltd.). ) Was calculated as the average value of each. Table 2 shows the results. FIG. 1 shows an example of a scanning electron micrograph of the composite material of the present invention obtained in Example 10. The one obtained in the present invention has a smaller carbon domain diameter, no large voids, and a uniform structure as compared with the example obtained in Comparative Example 2 (described below), which is a conventional method, in a scanning electron micrograph (FIG. 2). Was presenting.

Using the obtained composite material, the bending strength, thermal shock resistance, coefficient of friction and specific wear were measured. The results are shown in Table 2. In addition, these measuring methods are as follows. The bending strength was measured by a three-point bending test method according to JIS-R1601. Thermal shock resistance is
After using a test piece according to JIS-R1601, heating the test piece to a predetermined temperature under an inert atmosphere, immediately dropping the sample into normal-temperature water and rapidly cooling the sample, a three-point bending test according to JIS-R1601 was performed. The evaluation was made based on the temperature difference at which the strength rapidly decreased. The coefficient of friction and the specific wear are 5
0mm, 10mm thick disk-shaped test piece and 10mm diameter
A tungsten carbide pin having a length of 15 mm and a length of 15 mm was slid under conditions of an applied load of 10 kg and a sliding speed of 1 m / sec. A test piece was used on the fixed side, and tungsten carbide was used on the rotating side. The friction coefficient was calculated from the torque during sliding, and the wear amount was calculated from the weight change of the test piece when the sliding distance reached 10 ⁴ m. As a result, the composite material obtained by the present invention is a normal-pressure sintering, exhibits a high-density sintered body having a small porosity, a high strength, a small thermal shock resistance, a low friction coefficient, and a small sliding wear. The characteristics were excellent.

[0023]

[Table 1]

[0024]

[Table 2]

Comparative Examples 1 to 3 In the same manner as in Examples 1 to 13, the carbon source, ceramic powder having an average particle size of 0.1 to 3 μm, , And calcined at a temperature shown in Table 1 under a nitrogen atmosphere. After granulation by spray drying, the mixture was molded by a mold molding method and fired under the conditions shown in Table 1. The domain diameter of the carbon in the obtained composite material, the domain area ratio and the total porosity, and the bending strength, thermal shock resistance, friction coefficient and specific wear of the obtained composite material were determined as in Examples 1 to 13. Table 2 shows the measurement results in the same manner.
It was shown to. As a result, the composite material obtained in the comparative example had a high porosity, a low strength, was inferior in thermal shock resistance, had a high coefficient of friction and a specific wear amount, and was inferior in sliding characteristics.

Example 14 The composite material obtained in Example 1 was subjected to bearing processing, and when used, showed no lubrication and long-term durability.

Example 15 When the composite material obtained in Example 2 was applied to a mechanical seal, the sealability was better and the durability was longer than that of the conventional material.

Example 16 When the composite material obtained in Example 3 was used as a coal slurry flow rate valve, the slurry could be cut off smoothly, had good sliding characteristics, and had good wear resistance. there were.

Example 17 The composite material obtained in Example 4 was precision machined,
When used as a magnetic head substrate, the durability was good without damaging the mating media.

Example 18 When the composite material obtained in Example 7 was used as a twisted ring, it exhibited lower wear and higher durability than conventional ceramics.

Example 19 When the composite material obtained in Example 10 was used as a disc valve for a mixing faucet, low torque slidability and high durability were exhibited as compared with conventional ceramics.

[0032]

INDUSTRIAL APPLICABILITY According to the present invention, conventional ceramics - compared to carbon-based composite material, superior strength, sliding properties, and also the thermal shock resistance, very suitable ceramic as a sliding part
A carbon-based composite material is obtained .

[Brief description of the drawings]

FIG. 1 is a scanning electron micrograph showing the carbon dispersion state and shape of the ceramic-carbon composite material of the present invention obtained in Example 10.

FIG. 2 is a scanning electron micrograph showing the dispersion state and shape of carbon in the ceramic-carbon composite material obtained in Comparative Example 2.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C04B 35/563 C04B 35/56 S 35/58 101 35/04 Z F16C 33/24 E (56) References JP-A-61- 58862 (JP, A) JP-A-60-141676 (JP, A) JP-A-60-112670 (JP, A) JP-A-59-131577 (JP, A) JP-A-6-48836 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C04B 35/00-35/84 F16C 33/24

Claims (3)

(57) [Claims] 1. A ceramic powder (however, silicon carbide powder)
Except) in H / C of 0.2 to 2.0, condensed polycyclic aromatic compounds N and S content average molecular weight of less than 2%, respectively 100 to 2000 and / or polycondensation aromatics,
And, if necessary, mixing a sintering aid powder,
Calcined at 00 ° C., and then granulated, then fired, the carbon domain diameter is 0.01 to 30 μm,
A method for producing a ceramic-carbon composite material having a carbon domain area ratio of 5 to 70%. 2. The method according to claim 1, wherein the ceramic powder is one or more of oxides, carbides, nitrides, and borides. 3. The manufacturing method according to claim 1, wherein the mechanical element has a movable part thereof, and is a sliding component which is in temporary or constant contact and relatively slides, at least a sliding surface of which is provided. A sliding component comprising the ceramic-carbon-based composite material obtained in (1).