JPH05279679A - Sliding member - Google Patents

Abstract

PURPOSE:To provide a sliding member containing a ceramic, having a sliding surface to be exposed to the atmosphere of a fluorine-contg. cooling medium, hard to develop its scorching or unusual wear in the atmosphere of CFCs, and high in the lubricating effect in the atmosphere of chlorine-free CFCs. CONSTITUTION:The objective sliding member which is a pair of ring members constituting a pair of sliding surfaces being in contact with each other and has the above-mentioned advantages, is made up of (A) a member constituting a sliding surface which is a ring of spherical graphite cast iron and (B) the other member constituting the other sliding surface with such a material as to contain a ceramic such as alumina, silicon carbide, silicon nitride, boron nitride, carbon fiber-reinforced silicon nitride, silicon carbide whisker-reinforced alumina, or silicon carbide nanoparticle-dispersed-and-reinforced alumina in spherical graphite cast iron or bearing steel. The surface roughness of the sliding surfaces is <=1.0mum Ra.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding member, and more particularly to a sliding member used in an atmosphere of a cooling medium.

[0002]

2. Description of the Related Art Conventionally, chlorofluorocarbon (CF), which is a kind of fluorocarbon (hereinafter referred to as chlorofluorocarbon), is used as a cooling medium in refrigerators, refrigerators, car air conditioners and the like.
C) has been used. Among these chlorofluorocarbons, a typical cooling medium is CFC1.
It is 2. Chlorine (Cl) is contained in the molecule of CFC12.
It is included. This chlorine prevents adhesion and reaction of the sliding member on the sliding surface. That is, chlorine, as an extreme pressure additive, prevents seizure between sliding surfaces. Therefore,
The CFC 12 containing chlorine itself serves as a very effective lubricant. For this reason, it is difficult for the sliding portion of the sliding member to seize or to abnormally wear under a fluorocarbon atmosphere such as CFC12. For this reason, conventionally, a metal member such as cast iron has been used for a sliding portion used in an atmosphere of a cooling medium such as a refrigerator compressor.

[0003]

As described above, in a fluorocarbon atmosphere containing chlorine, even if a metal member such as cast iron is used for the sliding portion, seizure or abnormal wear of the sliding portion does not occur. There wasn't.

However, in recent years, due to the problem of ozone layer depletion in the stratosphere, use of chlorofluorocarbon represented by CFC12 has been restricted. This is because chlorine contained in chlorofluorocarbon is one of the causes of destroying the ozone layer. As a substitute for this chlorofluorocarbon, for example, HFC134a, which does not contain chlorine in its molecule, is considered promising. In this way, studies are underway to use chlorofluorocarbon-free fluorocarbon as a cooling medium. However, with CFCs that do not contain chlorine, the lubricating effect of chlorine cannot be expected. Therefore, there is a problem that metals such as cast iron used for sliding parts such as compressors are seized or abnormal wear occurs.

The present invention has been made in order to solve the above-mentioned problems, and even in an atmosphere of freon,
An object of the present invention is to provide a sliding member that is unlikely to cause seizure or abnormal wear.

[0006]

A sliding member according to the present invention is a sliding member having a sliding surface placed in an atmosphere of a cooling medium containing fluorine, the sliding member being made of ceramics. Contains.

According to a preferred first aspect of the present invention, the sliding member is composed of a pair of members constituting a pair of sliding surfaces that are in contact with each other, and at least one member is made of ceramics.

According to a preferred second aspect of the present invention, the surface roughness of the sliding surface is 1.0 μmRa or less.

[0009]

As a result of intensive studies made by the present inventors in view of the above, the inclusion of ceramics in the sliding member used in the atmosphere of the cooling medium containing fluorine prevents seizure and abnormal wear. Found above to be very effective.

The reason why seizure and abnormal wear can be prevented is considered as follows. Ceramics has a higher Young's modulus and less chemical reactivity than metal materials such as cast iron. Since the chemical reactivity is poor, it is difficult for reactions such as chemical adhesion to occur on the sliding surface of the sliding member containing ceramics. Therefore, it is possible to prevent seizure and abnormal wear due to chemical adhesion or the like in the sliding member containing ceramics. Therefore, even when used in an atmosphere of a cooling medium containing fluorine such as CFCs that does not contain chlorine, the sliding member containing ceramics operates normally.

The atmosphere of the cooling medium containing fluorine in the present invention may be at least one of the gas and liquid of freon. Furthermore, the cooling medium of the present invention is
It may be at least one of hydrofluorocarbon (HFC) and hydrochlorofluorocarbon (HCFC).

The molecular formula of a typical hydrofluorocarbon is shown in Table 1.

[0013]

[Table 1]

The present invention is also effective for hydrofluorocarbons other than those shown in Table 1.

Table 2 shows the molecular formulas of typical hydrochlorofluorocarbons.

[0016]

[Table 2]

The present invention is also effective for hydrochlorofluorocarbons other than those shown in Table 2.

The ceramics used in the present invention are oxides,
It is preferably at least one selected from the group consisting of carbides, nitrides, borides, and silicides. Tables 3 and 4 show typical monolithic ceramics and composite materials.

[0019]

[Table 3]

[0020]

[Table 4]

In the present invention, ceramics other than those shown in Tables 3 and 4 can also be used.

The sliding member is composed of a pair of members forming a pair of sliding surfaces that are in contact with each other, and at least one member is preferably made of ceramics. In this case, one member constituting the sliding surface needs to be ceramics, but the other member may be metal, and may be any material such as ceramics of the same kind or different kinds, carbon materials, resins such as Teflon, etc. ..

The present inventors have also found that there is a relationship between the surface roughness of the sliding surface of the sliding member of the present invention, seizure resistance, and wear. According to this, the surface roughness of the sliding surface of the sliding member of the present invention is preferably 1.0 μmRa or less. When the surface roughness of the sliding surface is 1.0 μmRa or more, one ceramic member may damage the other metal member or one ceramic member and the other ceramic member may be abnormally worn depending on the surface pressure of the sliding surface. This is because there is a risk of causing On the other hand, when the surface roughness of the sliding surface is 1.0 μmRa or less, one ceramic member hardly scratches the other member or causes abnormal wear with the other member. The reason for this is considered as follows.

The surface roughness of the sliding surface of the sliding member is 1.0 μm.
By setting Ra or less, the unevenness of the sliding surface becomes small. That is, the surface becomes smooth. For this reason, abrasion is less likely to occur even when the sliding portion suddenly contacts due to disturbance or the like. As a result, the sliding surface is 1.0 μmR
By setting it to a or less, it becomes possible to suppress a mechanical friction phenomenon.

Further, the inventors of the present invention set the surface roughness of the sliding surface of the sliding member of the present invention to 0.1 μmRa or less, so that a particularly excellent low friction coefficient is obtained in the atmosphere of the cooling medium containing fluorine. And found that wear resistance can be achieved. According to this, it is more preferable that the sliding surface of the sliding member of the present invention has a surface roughness of 0.1 μmRa or less.
This is because by setting the surface roughness to 0.1 μmRa or less, the unevenness of the sliding surface can be further reduced, thereby further suppressing the mechanical friction phenomenon even in the atmosphere of the cooling medium containing fluorine. It is thought that it is possible to do.

The sliding member of the present invention can be applied to compressor parts such as refrigerators, refrigerators, car air conditioners and room air conditioners used in an atmosphere of a cooling medium containing fluorine. Further, the present invention is not limited to these compressor parts, and can be applied to all other parts having a sliding portion used in an atmosphere of a cooling medium containing fluorine.

The cooling medium containing fluorine in the present invention is
It may be a CFC containing chlorine or a CFC containing no chlorine.

[0028]

【Example】

Example 1. A spheroidal graphite cast iron ring was used as one of the members constituting the sliding surface. The other member that constitutes the sliding surface is made of spheroidal graphite cast iron, bearing steel, alumina, silicon carbide, silicon nitride, boron nitride, carbon fiber reinforced silicon nitride, silicon carbide whisker reinforced alumina, and silicon carbide nanoparticle dispersion reinforced alumina. I created a ring to be. With respect to this one ring and the other ring, the seizure load was measured using a ring-on-ring tester while changing the load at a peripheral speed of 2 m / sec in the HFC134a liquid. The results of this experiment are shown in Table 5. In addition, 1-1 to 1-7 are examples of the present invention, and 1-8 and 1-9 are comparative examples.

[0029]

[Table 5]

As is clear from the results shown in Table 5, in the example of the present invention in which one member constituting the sliding surface is made of ceramics (monolithic ceramics, composite material), the seizure load is extremely higher than that in the comparative example. Turned out to be expensive. From this, it was found that in the example of the present invention, seizure was unlikely to occur even in the atmosphere of the cooling medium containing fluorine.

Example 2. Rings were made from mullite, silicon carbide, silicon nitride, aluminum nitride, boron carbide, alumina fiber reinforced crystallized glass, silicon carbide whisker reinforced silicon nitride, silicon carbide nanoparticle dispersed strengthened silicon nitride, flake graphite cast iron, and aluminum. By sliding each ring together, HCFC22 / HFC152a / HCFC12
The seizure load was measured using the ring-on-ring tester while changing the load at a peripheral speed of 3 m / sec in the CFC mixed alternative CFC liquid of No. 4. In this measurement, the surface roughness of the sliding surface was changed between 0.01 and 3 μmRa, and the seizure load at each surface roughness was evaluated. When co-sliding ceramics, the seizure load was defined as the point when crying occurred during the test and vibration of the tester occurred. The results of this experiment are shown in Table 6. 2-1 to 2-8 are examples of the present invention, and 2-9 and 2-10 are comparative examples.

[0032]

[Table 6]

As is clear from the experimental results shown in Table 6,
In the example of the present invention in which the member constituting the sliding surface is ceramics (monolithic ceramics, composite material), the seizure load was extremely higher than that in the comparative example. Than this,
It was found that the examples of the present invention hardly cause seizure even in the atmosphere of the cooling medium containing fluorine. It was also found that the smaller the surface roughness, the greater the load required for seizure. In particular, it has been found that the seizure load becomes extremely high when the surface roughness is 0.1 μmRa or less.

Example 3. In a swash plate type compressor for a car air conditioner, a shoe in contact with a swash plate made of a carbon fiber reinforced carbon composite material is made of silicon nitride, boron nitride, titanium nitride particle dispersion reinforced silicon nitride and bearing steel, respectively.
The seizure peripheral speed was evaluated using C134a as a refrigerant and polyalkylene glycol as a lubricant. At this time, the surface roughness of the sliding surface of the shoe was 0.1 μmRa. It should be noted that whether or not the image was burned was judged by the occurrence of abnormal noise and the abnormal increase in the drive current value. The results of this experiment are shown in Table 7. 3-1
3 to 3 are examples of the present invention, and 3-4 are comparative examples.

[0035]

[Table 7]

As is apparent from Table 7, the material of the shoe is ceramics (monolithic ceramics, composite material).
It was found that in Example of the present invention consisting of, the seizure peripheral speed was much higher than that in Comparative Example. From this, it was revealed that in the example of the present invention, it was difficult to seize even in the atmosphere of the cooling medium containing fluorine.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location C10N 20:00 Z 8217-4H 20:06 B 8217-4H Z 8217-4H 30:06 40:02 40:30 (72) Inventor Akira Yamakawa 1-1-1 Kunyokita, Itami City, Hyogo Prefecture Sumitomo Electric Industries, Ltd. Itami Works

Claims (3)

[Claims] 1. A sliding member having a sliding surface placed in an atmosphere of a cooling medium containing fluorine, wherein the sliding member contains ceramics.
Sliding member. 2. The sliding member according to claim 1, wherein the sliding member is composed of a pair of members forming a pair of sliding surfaces that are in contact with each other, and at least one member is made of ceramics. .. 3. The sliding member according to claim 1, wherein the surface roughness of the sliding surface is 1.0 μmRa or less.