JP3419478B2 - bearing - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to bearings such as rolling bearings and sliding bearings.

[0002]

2. Description of the Related Art Conventionally, as rolling bearings used in special environments where metal materials cannot be used, such as high temperature environments and corrosive environments, bearing parts such as races and rolling elements are made of alumina ceramics or non-oxide. Ceramic bearings formed of Si-based ceramics or the like are provided.

However, under the above high temperature environment, oil lubrication cannot be adopted as lubrication for ceramic bearings, so molybdenum disulfide, gold, silver and tetrafluoride are formed on the bearing raceway and rolling element surface. Ethylene resin (PTF
E), have been made to coat a solid lubricant such as graphite.

[0004]

[SUMMARY OF THE INVENTION However, the solid lubricant is poor in adhesion to the ceramic, so easily peeled off from the base material, when using ceramic bearings in a high temperature environment, relatively early in the lubricating There is a problem in that a defect occurs and the bearing life is shortened. The present invention has been made in view of the above problems, and an object of the present invention is to provide a bearing that can maintain a good lubrication state for a long period of time in a high temperature environment and that can achieve a long life. And

[0005]

In order to achieve the above object, the bearing of the present invention has at least one of two relatively sliding parts formed of a non-oxide Si-based ceramic as a base material. Bearings, the sliding surface of the bearing component made of the non-oxide Si ceramics has
By 00 slides the surface of the base material while supplying carbon-based lubricant at a high temperature of ° around C, and that was coated with the carbon-based lubricant in a state in which to produce a Si oxide film on the sliding surface It is a feature.

[0006]

SUMMARY OF] According to the bearing of the above construction, the sliding surface of the bearing component formed of non-oxide Si-based ceramics, sliding surface of the base material while supplying carbon-based lubricant at a high temperature of around 300 ° C by, since the coating the carbon-based lubricant in a state in which to produce a Si oxide film on the sliding surface, than without forming such Si oxide film, a carbon with respect to the sliding surface the system lubricant can be firmly adhered. Therefore, especially in the high temperature environment of around 300 ° C, it is possible to ensure good lubricity due to carbon-based lubricant.

[0007]

Embodiments will be described in detail below with reference to the accompanying drawings showing embodiments. FIG. 1 is an enlarged sectional view of a rolling bearing showing an embodiment of the present invention. In this rolling bearing, a plurality of balls 3 as rolling elements also constituting bearing components are interposed between an inner ring 1 and an outer ring 2 as bearing rings constituting bearing components, and each ball 3 is It is held by a holder (not shown).

The inner ring 1, the outer ring 2 and the balls 3 as the bearing parts are each formed of a non-oxide Si (silicon) type ceramic as a base material. This non-oxide Si
As ceramics, SiC, Si3 N4, Si3
N4 -TiC and the like can be exemplified. Further, a Si oxide film 4 is formed on at least the surface of the base material of at least the race portions 1a, 2a of the inner and outer rings 1, 2, and the Si oxide film 4
On the surface of the graphite 5 as carbon-based solid lubricant is coated.

Further, Si is also formed on the surface of the base material of each ball 3.
An oxide film 4 is formed, and the surface of this Si oxide film 4 is coated with graphite 5. This S
The formation of the i-oxide film 4 and the coating of the graphite 5 are
As in Tests 1 and 2 described later, the test is performed by sliding the base material surfaces while supplying the graphite 5 at high temperature. In the rolling bearing configured as described above, each ball 3 makes rolling contact with the respective track portions 1a, 1a of the inner and outer races 1, 2 with a slight slip (sliding). Therefore, the surfaces of the track portions 1a and 2a and the surface of the ball 3 have not only a function as a rolling surface,
It also has a function as a sliding surface. Then, with respect to the minute slip, graphite 5 coated on the surface of each of the inner and outer rings 1, 2 and ball 3 acts as a good lubricant <br/>. Moreover, this graphite 5 is Si
Since the oxide film 4 firmly adheres to the surface of the base material, it exhibits good lubricating performance for a long period of time, especially in a high temperature environment of about 300 ° C.

[0010] was subjected to the following friction test to ensure that the improved adhesion of the carbon-based lubricants such as graphite 5 by Test 1 above Si oxide film 4. 1. Test method Samples made of SiC were rubbed while supplying carbon black, and the adhered state of carbon on the sliding surface after rubbing was observed. However, the above carbon black is
It is generated by burning benzene and ethanol, and exhibits the same lubricating characteristics as graphite. The ambient temperature was 400 ° C. 2. Test Results FIG. 4 shows the results of observing the sliding surface of the sample rubbed while supplying carbon black by EPMA, of which (a) is an SEM image and (b) is C-.
Kα image, (c) is an O-Kα image, and (d) is an S image.
It is an i-Kα image. It can be seen from FIGS. 10A and 10C that SiO2 (corresponding to the white portion in the photograph) is formed in an island shape on the sliding surface. Further, as is clear from FIG. 9B, a strong C-Kα ray was obtained in the SiO2 portion, and it is understood that SiO2 and carbon exhibit good adhesion.

In the above friction test, it is considered that SiO2 is first formed in the initial stage of friction, and then carbon is adhered to the surface of the SiO2. In order to confirm this point, samples made of SiC were rubbed with each other in an unlubricated state, and the sliding surface and the non-sliding surface of the samples were FT-IR.
The spectrum was measured. The result is shown in FIG. However, (a) of the figure shows the measurement result of the non-sliding surface, and (b) shows the measurement result of the sliding surface. From the figure, it can be seen that SiO2 (the white part in the photograph corresponds) is formed on the sliding surface.

FIG. 2 shows the result of further observation of the sliding surface of the above sample by EPMA, in which (a)
Is an SEM image, (b) is a C-Kα image, (c)
Is an O-Kα image, and (d) is a Si-Kα image. It can be seen from FIGS. 11A and 11C that island-shaped SiO2 is produced on the sliding surface. Further, from FIG.
It can be seen that the strength of the C-Kα ray is weakened in the SiO2 portion due to the decomposition of the base material.

Test 2 The following friction test was conducted on the samples consisting of the five types of ceramics shown in Table 1 to determine the friction coefficient at ambient temperature from room temperature to 400 ° C. 1. Test method Samples made of the same type of ceramic were frictionally rotated by relatively rotating while applying a load while supplying carbon black, and the frictional force at this time was measured by a load cell. The carbon black is generated by burning benzene and ethanol. 2. Test conditions (1) Test piece load 53.9N (2) Sliding speed 0.1mm / sec (3) Atmosphere temperature Room temperature to 400 ° C

[0014]

[Table 1] The results of the friction test are shown in FIG. From FIG. 5, it can be seen that the alumina-based ceramics do not show a large change in the friction coefficient depending on the ambient temperature, but the non-oxide Si-based ceramics show good lubricating characteristics particularly in the temperature range of 300 ° C. . The relationship between the ambient temperature and the specific wear amount of SiC is as shown in FIG.
It can be seen that the specific wear amount is small in the temperature range of 300 ° C.

The [0015] above, the SiO2 was formed on the sliding surface of the non-oxide Si-based ceramics, if coating the carbon-based lubricant on the surface, it is clear that can improve the lubricating properties. The present invention can be applied to all bearings including sliding bearings, as long as at least one of the two relatively sliding bearing components is made of non-oxide Si ceramics. Examples of the carbon-based lubricant include graphite and carbon black, and glassy carbon fiber.

[0016]

As described above, according to the bearing of the present invention, the carbon-based lubricant is applied to the sliding surface of the component made of non-oxide Si-based ceramics at a high temperature around 300 ° C. by sliding the base material surface while supplying, since coating the carbon-based lubricant <br/> in a state to produce a Si oxide film on the sliding surface, the carbon-based to the sliding surface The lubricant can be firmly adhered, and a good lubrication state can be maintained for a long period of time. Therefore, there is a peculiar effect that the life of the bearing can be extended.

[Brief description of drawings]

FIG. 1 is a sectional view of a rolling bearing showing an embodiment of the present invention.

FIG. 2 is a photograph of a structure of a sliding surface of ceramics, in which (a) is a SEM image, (b) is a C-Kα image, (c) is an O-Kα image, and (d). Is a Si-Kα image.

FIG. 3 is a graph showing FT-IR spectrum measurement results of a sliding surface of ceramics, of which (a) is a non-sliding surface measurement result and (b) is a sliding surface measurement result. is there.

FIG. 4 is a microstructure photograph of a sliding surface of ceramics, in which (a) is a SEM image, (b) is a C-Kα image, (c) is an O-Kα image, and (d). Is a Si-Kα image.

FIG. 5 is a graph showing the relationship between ambient temperature and friction coefficient.

FIG. 6 is a graph showing the relationship between ambient temperature and specific wear amount.

[Explanation of symbols]

1 Inner ring (race ring) 2 outer ring (race ring) 3 balls (rolling elements) 4 Si oxide film 5 graphite

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) F16C 33/00-33/66 C04B 41/87

Claims (2)

(57) [Claims] 1. A bearing in which at least one of two relatively sliding bearing components is formed of a non-oxide Si-based ceramic as a base material, and a bearing component made of the non-oxide Si-based ceramic is slidable. the sliding surface, by sliding the base material surface while supplying a carbon-based lubricant at a high temperature of around 300 ° C,
A bearing, wherein the sliding surface is coated with the carbon-based lubricant in a state where a Si oxide film is formed. 2. The two bearing parts which slide relative to each other,
The bearing according to claim 1, which is a bearing ring and a rolling element of a rolling bearing.