JPH09165281A - Sliding composite material - Google Patents

Abstract

(57) Abstract: 10 parts of carbon are added to 100 parts by weight of silicon carbide.
˜50 parts by weight, and the peak area ratio of the laser Raman spectral intensity of the crystalline phase to the amorphous phase of the carbon is 0.1 to 1
0.0 and a bulk density of 2.0 to 2.8 g / cm
³ , and in the open pores of the silicon carbide-carbon composite material having 5 to 50% by volume of open pores, a single substance or two or more substances having a lubricity and being liquid, grease-like or solid at room temperature A slidable composite material characterized by being mixed and filled. [Effect] The slidable composite material of the present invention is particularly good in sliding in a dry atmosphere, and the composite of carbon suppresses exudation of a lubricating component and exhibits excellent sliding characteristics for a long period of time. .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slidable composite material which is obtained by subjecting a silicon carbide-carbon composite material to an oil impregnation treatment and which is suitably used for a sliding structure member or the like.

[0002]

2. Description of the Related Art Since silicon carbide is excellent in hardness, heat resistance and corrosion resistance, its application as a structural member has been actively studied in recent years. In particular, they have been partially put into practical use as structural members such as mechanical seals and bearings. However, since silicon carbide has poor sliding characteristics in a dry atmosphere, its use range is limited.

In order to solve such a problem, a method of impregnating porous ceramics such as silicon carbide and alumina with lubricating oil is disclosed in Japanese Patent Laid-Open No. 61-281086. Further, JP-A-2-217380 discloses a method of impregnating a porous ceramic with a lubricating oil and / or a solid lubricant.

However, in any of the above-mentioned methods, the slidability of the base material, ceramics, is low, so the sliding becomes unstable, and the friction coefficient rapidly increases due to the decrease and deterioration of the lubricant. It has been pointed out that the mechanical part having the sliding part is damaged. In addition, since the open pores of the ceramic are simply filled with oil, the oil carrying force of the base material is small, and the exudation caused by this is also a problem. On the other hand, in order to stabilize sliding, a larger amount of lubricant is required, and the inherent high strength and high hardness characteristics of ceramics may be sacrificed.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to improve the sliding characteristics of a base material by compounding carbon as a base material ceramics, and to impregnate the open pores with a lubricating component. As a result, sliding in a dry atmosphere is improved, and since the composite carbon in the open pores carries the impregnating oil, exudation of the impregnating oil is suppressed and excellent sliding characteristics are exhibited for a long period of time. To provide the material.

[0006]

The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, while using a silicon carbide-carbon composite material having excellent sliding characteristics in a dry atmosphere, The present invention has been completed by optimizing the manufacturing method in which the lubricant is impregnated.

That is, the gist of the present invention is (1) containing 10 to 50 parts by weight of carbon per 100 parts by weight of silicon carbide,
The peak area ratio of the laser Raman spectral intensity of the crystalline phase to the amorphous phase of carbon is 0.1 to 10.0, the bulk density is 2.0 to 2.8 g / cm ³ , and 5 to 50% by volume. The open pores of the silicon carbide-carbon composite material having open pores described above are filled with a substance having a lubricity and being liquid, grease-like or solid at room temperature, either alone or as a mixture of two or more kinds. (2) The average diameter of open pores of the silicon carbide-carbon composite material is 0.05.
10 μm to 10 μm, the slidable composite material according to (1) above, and (3) 10% by volume or more of the open pore volume of the silicon carbide-carbon composite material is filled with a substance having lubricity. The slidable composite material according to the above (1) or (2), wherein the substance having lubricity is a fluorine-based oil and / or a silicone-based oil, a fluororesin, graphite, 1 selected from the group consisting of molybdenum sulfide, tungsten disulfide, titanium disulfide, boron nitride, paraffin wax, and stearin
The slidable composite material according to any one of (1) to (3) above, which is a mixture of at least one kind.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The slidable composite material of the present invention comprises a specific silicon carbide-carbon composite material having open pores with a liquid substance, a grease-like substance or a solid-like substance having a lubricating property at room temperature,
It is characterized by being filled alone or as a mixture of two or more kinds. First, the silicon carbide-carbon composite material will be described.

The silicon carbide-carbon composite material used in the present invention contains 10 to 5 carbon atoms based on 100 parts by weight of silicon carbide.
0 parts by weight, and the peak area ratio of the laser Raman spectral intensity of the crystalline phase to the amorphous phase of the carbon is 0.1 to 10.0.
And has a bulk density of 2.0 to 2.8 g / cm ³ and open pores of 5 to 50% by volume.

The silicon carbide used as a raw material serves as a matrix after sintering, and may be either α-type or β-type crystal type. Further, the purity is preferably 90% by weight or more, and more preferably 95% by weight or more, for reasons such as reduction of density and prevention of deterioration of strength and fracture toughness.

The average particle size of silicon carbide used as a raw material is preferably 0.05 to 80 μm, more preferably 0.05 to 5 μm in terms of sliding characteristics. 80
The presence of particles exceeding μm may cause the particles to drop during sliding and impair the sliding characteristics.

The morphology of the composite carbon is a simple substance and is composed of a crystalline phase and an amorphous phase. The crystal phase of these simple substances is centered around 1580 cm ^{-1 by} laser Raman spectroscopy.
Has a peak from 00 to 1700 cm ^-1 , and
The amorphous phase is centered around 1360 cm ^-1 and 1300-1.
It has a peak up to 450 cm ^-1 . Therefore, the abundance ratio of the crystalline phase and the amorphous phase in the simple substance in the crystalline phase can be known from the peak area ratio, and in the present invention, the peak of the laser Raman spectral intensity of the crystalline phase with respect to the amorphous phase of carbon is obtained. The area ratio is 0.1 to 10.0, preferably 0.
It is 5 to 6.0. If the peak area ratio (abundance ratio) is outside this range, the mechanical properties are inferior, which is not preferable.

The amount of carbon to be combined is 10 to 50 parts by weight of carbon with respect to 100 parts by weight of silicon carbide, and preferably 15 to 40 parts by weight of carbon with respect to 100 parts by weight of silicon carbide. If the amount of carbon is less than 10 parts by weight, the sliding characteristics of the base material will not be exhibited and the holding power of the lubricating oil will be reduced. If it exceeds 50 parts by weight, the dispersion of carbon in the composite material becomes poor and the strength,
Mechanical properties such as hardness deteriorate.

The silicon carbide-carbon composite material as the base material can be manufactured by a general molding method such as CIP or slip casting. At that time, if necessary, an additive usually used, for example, a sintering aid such as a boron compound can be used. Moreover, you may add an organic binder as needed.

The molded body may be fired after being processed into any shape. Moreover, you may bake after performing a degreasing process as needed. The firing method may be either a pressure or a pressureless sintering. Since the firing atmosphere needs to be a condition that the material is not oxidized, the firing atmosphere is performed in an inert atmosphere such as vacuum, argon, helium, or nitrogen. The firing temperature is 1800-230
Sinter in the temperature range of 0 ° C. When the temperature is lower than 1800 ° C,
Since the sintering is insufficient, the particles are shattered during sliding and the sliding characteristics are impaired. Further, at a temperature exceeding 2300 ° C., the particle size of silicon carbide particles becomes large and the mechanical properties deteriorate.

The bulk density of the silicon carbide-carbon composite material (sintered body) obtained by the above manufacturing method is 2.0 to 2.8.
g / cm ³ , preferably 2.3 to 2.7 g / cm
³ Further, the silicon carbide-carbon composite material is 5 to 5
It has 0% by volume of open pores, preferably 1
It is 0 to 30% by volume. If the open pores are less than 5% by volume, a small amount of the lubricating component can be impregnated, and the sliding characteristics cannot be maintained for a long period of time. On the other hand, if it exceeds 50% by volume, the compactness of the base material becomes insufficient, which causes problems such as deterioration of strength and hardness and shedding during sliding.

The open pores of the silicon carbide-carbon composite material preferably have an average diameter of 0.05 to 10 μm, more preferably 0.1 to 3.0 μm. If the average diameter is less than 0.05 μm, it becomes difficult to impregnate the lubricant, and 10
When it exceeds μm, the bearing capacity of the lubricating oil is reduced, the friction coefficient is increased due to oil shortage, and the mechanical parts are contaminated. The average diameter of the open pores is measured by the mercury injection method (for example, Poisizer 9320 manufactured by Shimadzu Corporation).

Next, the slidable composite material of the present invention will be described. The slidable composite material of the present invention includes, in the open pores of the silicon carbide-carbon composite material as described above, a single substance or a mixture of two or more substances that have lubricity and are liquid, grease-like or solid at room temperature. It is characterized by being mixed and filled.

The method of filling the open pores with the substance having lubricity is not particularly limited, but an impregnation method such as vacuum impregnation or high pressure impregnation is preferably used. Further, the substance having lubricity (hereinafter referred to as “lubrication component”) may be a substance which is liquid, grease-like or solid at room temperature (25 ° C.) and has an effect of improving the coefficient of friction and wear characteristics. There is no particular limitation, and any known substance such as a lubricant can be used.

The liquid or grease-like lubricating components at room temperature include general lubricating oils, mechanical oils, resins or silicone oils such as methyl silicone, dimethyl silicone, methylphenyl silicone, trifluoroethylene chloride, fluoroethylene, etc. Any of the above fluorinated oils may be used. From the viewpoint of heat resistance and chemical resistance, silicone oil and fluorine oil are preferable.

As the lubricating component which is solid at room temperature, fluororesin, graphite, molybdenum disulfide, tungsten disulfide, titanium disulfide, boron nitride, paraffin wax and stearin are preferable.

In the present invention, liquid or grease-like lubricating components may be used alone or as a mixture of two or more, or one or more solid lubricating components may be mixed with the liquid or grease-like lubricating components and used. In the present invention, in particular, from the viewpoint of long-term stability of sliding, the lubricating component is fluorine-based oil and / or silicone-based oil, and fluorine resin, graphite, molybdenum disulfide, tungsten disulfide, titanium disulfide, boron nitride, paraffin. It is desirable to mix one or more kinds selected from the group consisting of wax and stearin.

In the present invention, it is preferable that 10% by volume or more of the open pore volume of the silicon carbide-carbon composite material is filled with a substance having a lubricity so that good sliding characteristics can be obtained. More preferably, the filling amount is 50% by volume or more.

The slidable composite material of the present invention has a small coefficient of friction and a small amount of specific wear and is excellent in sliding characteristics. For example, bearings, ball bearings, roll bearings, water and chemical valves, mechanical seals, etc. It can be suitably used as a machine part having sliding.

[0025]

The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

Examples 1 to 10 and Comparative Examples 1 to 4 [alpha] -type silicon carbide having an average particle diameter of 0.7 [mu] m was prepared by adding 2% by weight of boron carbide as a sintering aid and coal tar pitch as a carbon source in the amounts shown in Table 1. In addition, wet mixing was performed in toluene, and the mixture was calcined in nitrogen at the calcining temperature shown in Table 1. The calcined powder was pulverized in ethanol and granulated with a spray dryer. The obtained powder is shown in Table 1 by the die molding method.
It was molded at the pressure shown in Table 1 and then baked at the baking temperature shown in Table 1 for 4 hours.

The obtained sintered body was processed into 20 × 28 × 5 mm, and the surface of 20 × 28 mm was ground to have Rmax = 0.8 μm or less. The above-mentioned processed body was vacuum impregnated with the lubricant shown in Table 2. A sliding test was conducted using the above slidable composite material. The sliding test is a ring-on-block method, and the above sample is used for the block part, and all the rings of the mating material are SUS304 (φ40
X40t). Table 2 shows the test conditions, in which the ring rotational speed was 300 rpm and the block load was 20 kgf in the atmosphere, and the initial dynamic friction coefficient was measured and the wear rate was calculated from the wear amount after 30 minutes.

[0028]

[Table 1]

[0029]

[Table 2]

As shown by the results in Table 2, all of the slidable composite materials obtained in the examples had good friction coefficient and wear amount. On the other hand, in Comparative Example 1 not impregnated with a lubricating component, the friction coefficient and wear amount are extremely inferior, and in Comparative Example 2 in which the lubricating component impregnation rate is low, the friction coefficient and wear amount are inferior, and the amount of composite carbon is small. The wear amount was inferior in Comparative Example 3, and the wear amount was inferior in Comparative Example 4 having a large pore diameter.

Example 11 A sliding composite material having the same physical properties as in Example 1 and a material having the same physical properties as in Comparative Example 3 were precision processed into bearings,
It was installed in a pump bearing and operated without lubrication, and the temperature change of the bearing was measured. As a result, as shown in FIG. 1, the bearing temperature of Comparative Example 3 increased from around 90 minutes, while the temperature of Bearing of Example 1 did not change significantly and stable sliding results were obtained. . In Comparative Example 3, a large amount of the impregnated lubricant leached out in a short time, causing oil shortage and an increase in the bearing temperature. In contrast, in Example 3, the carbon compounded the lubricating effect and the lubricant exudation. The suppressive effect of was exhibited, and good results were obtained.

Example 12 The slidable composite material obtained in Example 6 was precision processed into a flow control disk valve shape, and alumina was used as a mating material, and a built-in valve test was conducted. No increase in the operating load of the handle was observed, indicating stable slidability.

[0033]

EFFECT OF THE INVENTION The slidable composite material of the present invention is particularly good in sliding in a dry atmosphere, and exhibits excellent sliding characteristics for a long period of time by suppressing exudation of a lubricating component due to carbon composite. Is.

[Brief description of the drawings]

FIG. 1 shows the relationship between sliding time and bearing temperature when a material having the same physical properties as those of Example 1 and Comparative Example 3 was precision processed into a bearing and incorporated into a pump bearing and operated without lubrication. FIG.

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Claims (4)

[Claims] 1. Carbon is added to 100 parts by weight of silicon carbide.
0 to 50 parts by weight, and the peak area ratio of the laser Raman spectral intensity of the crystalline phase to the amorphous phase of the carbon is 0.1 to 1
0.0 and a bulk density of 2.0 to 2.8 g / cm
³ , and in the open pores of the silicon carbide-carbon composite material having 5 to 50% by volume of open pores, a single substance or two or more substances having a lubricity and being liquid, grease-like or solid at room temperature A slidable composite material characterized by being mixed and filled. 2. The slidable composite material according to claim 1, wherein the silicon carbide-carbon composite material has open pores having an average diameter of 0.05 to 10 μm. 3. The slidable composite according to claim 1, wherein 10% by volume or more of the open-pore volume of the silicon carbide-carbon composite material is filled with a substance having a lubricity. material. 4. A group in which the substance having lubricity is made of fluorine-based oil and / or silicone-based oil, fluororesin, graphite, molybdenum disulfide, tungsten disulfide, titanium disulfide, boron nitride, paraffin wax, and stearin. The slidable composite material according to any one of claims 1 to 3, which is a mixture of one or more selected from the following.