JPH0658434A - Ceramic sliding member - Google Patents

Abstract

(57) [Summary] [Construction] A ceramic sliding member is constructed with a flatness of 3 μm or less on the sliding surface of a ceramic body in which closed pores having a porosity of 3 to 30% by volume are uniformly dispersed. [Effect] Since smooth sliding can be performed for a long period of time without linking while maintaining a perfect sealing property, it can be suitably used as various valves, seal rings, slider parts and the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic sliding member used for valves, sliders, seals and the like.

[0002]

2. Description of the Related Art A Faucet valve used in a hot and cold water mixing valve is configured to open and close a fluid passage formed in each valve body by relatively moving two disc-shaped valve bodies in a state of sliding contact with each other. Has become. For example, as shown in FIG. 4 (A), the fixed valve body 30 and the movable valve body 20 are kept in contact with each other at their sliding contact surfaces 21 and 31.
By moving the movable valve body 20 by operating the lever 40 as shown in FIG.
By opening and closing 2, 32, the supply fluid is controlled to be opened and closed and adjusted.

The sliding members used as the movable valve body 20 and the fixed valve body 30 are required to have high dimensional accuracy in order to maintain slidability and sealability, and they are constantly slid against each other, causing severe wear. Corrosion was severe because it was constantly exposed to fluid. Therefore, in recent years, ceramics, which can be processed with high precision and have excellent wear resistance and corrosion resistance, have come to be used as sliding members.

In addition to this facet valve,
Ceramics have come to be used for sliding members such as various seal parts and bearing parts that require sealing properties.

By the way, the slidability and the sealability are contradictory to each other, and in order to improve the sealability, the sliding surface must be made extremely smooth. However, if so, smooth slidability may not be obtained. Are known. A typical example of this is what is called linking, which is the occurrence of catching and abnormal noise that occurs when a pair of members with extremely smooth surfaces are rubbed together, and finally sticking together. It is said that it is a phenomenon that becomes immobile, and it is said that intermolecular force at the molecular level, electrostatic force, vacuum adsorption, etc. are complicatedly entangled.

Since such linking does not occur unless the surface is smooth, various solutions have been considered. For example, it has been considered that minute irregularities are formed on the sliding surface of the ceramic sliding member or that the surface roughness is of an appropriate size (for example, JP-A-1-116638).
No. 6 publication).

There is also a ceramic sliding member made of porous ceramics having a three-dimensional mesh structure, and the open pores are impregnated with a resin or oil as a lubricant (Japanese Patent Laid-Open Nos. 61-206875 and 61-206875). -244980, 62
-4949, 62-37517, etc.).

Further, a lubricating film has been formed on the smooth sliding surface of the ceramic sliding member. As a lubricating film, in addition to forming an oil film by applying oil,
It has been considered to deposit carbon having a lubricating action or to coat SiC or the like.

[0009]

However, in the case where the sliding surface has minute irregularities, the sealing property may be deteriorated, and the sliding surface becomes smooth due to sliding wear during long-term use. If so, there was a problem that linking would eventually occur.

Further, the open pores of the three-dimensional reticulated ceramics impregnated with resin or the like are a composite material combined with a different material, so that the wear tends to proceed due to the hardness difference with other sliding members, Since the initial sliding contact surface is not maintained, there is a problem that linking eventually occurs. Further, since it is impregnated with a resin or the like, the heat resistance is low and the production is not easy.

Further, although the one having a lubricating film formed on the sliding surface is temporarily effective, it is inevitable that the lubricating film itself will be lost or worn and the occurrence of linking will be unavoidable after long-term use. There was a flaw. For example, in the case of a sliding member that relies on an oil film, when the oil film is cut off, linking occurs immediately, and in addition, impurities such as oil are mixed in the fluid. In addition, even if the sliding surface is vapor-deposited with carbon or SiC,
Since the effect acts only in the vicinity of the surface of the sliding surface, linking occurs even if the surface is slightly worn due to long-term sliding. Moreover, coating such as vapor deposition requires enormous labor and cost and is not suitable for mass production.

As described above, a ceramic sliding member which has excellent sealing property and does not cause linking for a long time has not been obtained yet.

[0013]

In view of the above, the present invention provides:
The closed pores having a porosity of 3 to 30% by volume are uniformly dispersed,
The sliding surface is a ceramic sliding member having a flatness of 3 μm or less.

In the present invention, the closed pores are
It means that at least each pore is not in communication between the sliding surface and the other surface.

[0015]

In the ceramic sliding member of the present invention, each pore is closed, and the flatness of the sliding surface is 3 μm or less, so that excellent sealing properties can be obtained. And
Since there are pores on the sliding surface, the contact area is reduced and the sliding resistance can be reduced. Further, since pores are present in the entire sliding member, pores appear one after another even when the sliding surface is worn, and the surface state similar to the initial state can be maintained, so that the occurrence of linking can be prevented even after long-term use. .

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in the sectional view of FIG. 1 and the enlarged view of the surface of FIG. 2, the ceramic sliding member 1 of the present invention is provided with a large number of independent pores 2 uniformly inside and on the surface. The porous body has a porosity of 3 to 30% by volume as a whole. The sliding surface 3 also has pores 2, and the portion of the sliding surface 3 excluding the pores 2 has a flatness of 3 μm.
The following is a very flat surface.

Now, when the ceramic sliding members 1 are pressed against each other and slid, the contact surface area can be reduced and the linking can be prevented due to the existence of the pores 2 in the sliding surface 3, and the fluid is interposed. When doing, the pores 2 on the sliding surface 3
Acts as a fluid pool, so that the sliding torque can be reduced by combining the self-lubricating action.

Further, since the ceramic sliding member 1 of the present invention has the pores 2 not only on the surface but also inside thereof, wear occurs during use and the surface layer of the sliding surface 3 is lost. However, since the same surface state appears one after another, no linking occurs even after long-term use.

The sliding surface 3 is a surface having a very high degree of flatness except for the pores 2. Moreover, since the pores 2 are closed pores independent of each other, the fluid leaks out through the pores 2. There is no fear.

In the ceramic sliding member of the present invention as described above, the porosity is set to 3 to 30% by volume because when the porosity is 3% or less, the effect of reducing the sliding torque is poor, and the porosity is 30%. This is because the wear resistance and the strength are reduced in the above. If the pores 2 are evenly present at a porosity of 3 to 30% by volume, the area occupancy of the pores 2 on the sliding surface 3 is also in the range of 3 to 30%.

Regarding the size of each pore 2, it is preferable that a large number of small pores having a pore diameter of 100 μm or less are present uniformly, but the pore diameter is 10 from the viewpoint of manufacturing described later.
It is preferably at least μm. Further, the pores 2 may have any shape, but a round shape is preferable so that cracks are less likely to occur from the pores 2.

In the above embodiment, the pores 2 are independent of each other, but in the present invention, at least the pores 2 need not communicate with the sliding surface 3 and other surfaces. For example, the surface other than the sliding surface of the ceramic body in which the respective pores communicate with each other may be sealed with glass or the like.

Further, in order to maintain the sealing property of the sliding surface 3, the flatness may be 3 μm or less, preferably 1 μm or less.

Next, a method of manufacturing the ceramic sliding member 1 of the present invention will be described.

First, the material of the ceramic sliding member 1 of the present invention is a sintered body containing alumina, zirconia, silicon carbide, silicon nitride or the like as a main component, and a known sintering aid is added if desired. be able to. For example, for alumina, SiO ₂ , MgO, etc .; for silicon carbide, C, B, Al ₂ O ₃ , Y ₂ O _3, etc .; and for silicon nitride, oxidation of elements of Groups 2a and 3a of the Periodic Table. It is possible to add Y ₂ O ₃ , CaO, MgO, CeO ₂ or the like to zirconia such as a substance or a nitride.

If a resin and a foaming agent are added to and mixed with these ceramic raw materials, and the mixture is molded into a predetermined shape and fired, the resin and the foaming agent are burnt off during firing to form the pores 2. it can. At this time, the porosity and the pore diameter can be freely adjusted by changing the addition amount of these resins and the foaming agent and the particle diameter. Further, it is not always necessary to mix the resin and the foaming agent, and the pores 2 can be formed by using a normal ceramic raw material and adjusting the firing conditions so as not to completely sinter.

Finally, the sliding surface of the obtained sintered body may be polished to a flatness of 3 μm or less, preferably 1 μm or less.

For example, when the ceramic sliding member 1 of the present invention is made of alumina ceramics, 80% by weight or more of Al ₂ O ₃ is the main component, and pores are formed together with a sintering aid such as SiO ₂ or MgO. Add resin and foaming agent,
After forming into a predetermined shape by press molding, after baking at a predetermined temperature in an oxidizing atmosphere, the sliding surface has a flatness of 3 μm.
The following extremely smooth surface may be polished and finished.

Although FIG. 1 shows an example in which the ceramic sliding members 1 of the present invention are slid together, only one of them is the ceramic sliding member 1 of the present invention, and the other is a dense ceramic body. For example, in the case of configuring a facet valve, at least one of the two valve bodies may be configured by the ceramic sliding member 1 of the present invention. Further, the ceramic sliding member of the present invention is not limited to sliding between ceramics, but can be suitably used for sliding with other materials such as metal and resin.

Further, in the above embodiment, an example in which flat surfaces are slid on each other has been shown, but in addition to this, the ceramic sliding member of the present invention can be applied even if the sliding surface is cylindrical or spherical. You can When the sliding surface has a curved shape, the flatness of 3 μm or less means that the flatness is 3 μm or less when the original curved shape is corrected. To do.

Therefore, the ceramic sliding member of the present invention can be used not only in the facet valve but also in various applications such as various valves such as ball valves, sealing materials and bearings.

Experimental Example Here, the pores 2 in the ceramic sliding member 1 of the present invention
Experiments were carried out to find the optimum range such as the size and amount.

A ceramic sliding member 1 made of alumina ceramics and having various Al ₂ O ₃ purity, porosity and pore diameter as shown in Table 1 was prepared. Each has an outer diameter of 30 mm and a thickness of 10 as shown in FIG.
A disc-shaped body 1 having a diameter of 5 mm and a fluid passage 12 having a diameter of 5 mm.
0 was set as 0, and a mirror-finished flatness of each sliding surface 11 was set to 1 μm or less. As a prototype, an experiment was conducted to check slidability and occurrence of linking.

The porosity was measured by the Archimedes method, and the pore diameter was measured on the basis of an enlarged photograph of the sliding surface 11, and is an average value of the maximum diameter of each pore.

[0036]

[Table 1]

First, as shown in FIG. 3, while pressing a pair of ceramic sliding members 1 and 1 from above and below with a force of 10 Kgf · cm, only one ceramic sliding member 1 is rotated to make the initial sliding torque. When the relationship between the value and the porosity of the ceramic member 1 was examined, it was as shown in FIG. From this result, it is clear that the lower the porosity, the higher the initial value of the sliding torque, and that the linking occurred when the porosity was 2.5% by volume. On the other hand, when the porosity was 3% by volume or more, it was at a usable level, and when it was 5% by volume or more, the sliding torque was particularly excellent at 10 kgf · cm or less.

Next, as an example of the present invention, one having a porosity of 10% by volume was used, and as a comparative example, one having an oil film formed on the sliding surface and one having carbon vapor-deposited were used, respectively, in the same manner as described above. The slide rotation was performed, and the relationship between the number of slides and the sliding torque value was investigated. The result is as shown in FIG.
In the comparative example in which the oil film or the carbon film is formed, the film peels off during the experiment, so the sliding torque gradually increases,
Eventually linking occurred. On the other hand, in the examples of the present invention, since the state of the surface does not change even when the sliding surface is worn as described above, the low sliding torque is maintained even when used for a long time, and the long-term good condition is maintained. It was confirmed that it can be used.

Then, in the same manner as above, the wear amount of the ceramic sliding member 1 after sliding 1000 times, the alumina purity, and the
The relationship between the pore diameter and the porosity was investigated. The result is Figure 7.
~ As shown in Fig. 9. First, as shown in FIG. 7, which shows the relationship between the Al ₂ O ₃ purity and the wear amount, the Al ₂ O ₃ purity is 80%.
It can be seen that the amount of wear can be made extremely small by the above.

Further, as shown in FIG. 8 showing the relationship between the pore diameter and the wear amount, it can be seen that the wear amount can be reduced by setting the pore diameter to 100 μm or less. It is considered that this is because when the pore diameter is large, the fine particles easily enter the pores, and the fine particles are easily caught and chipping easily occurs.

Further, as shown in the relationship between the porosity and the wear amount, as shown in FIG. 9, the wear amount can be reduced by setting the porosity to 30 μm or less.

From these results, in the ceramic sliding member 1 of the present invention, the porosity is set in the range of 3 to 30% by volume, preferably 5 to 20% by volume, and the pore size is 10 to 100 μm.
If the Al ₂ O ₃ purity is 80 wt% or more in m, the sliding torque is small and the amount of wear is small, so that it can be seen that it can be suitably used for a long period of time.

Although alumina ceramics was used in the above experimental examples, the same results were obtained when other ceramics were used.

[0044]

As described above, according to the present invention, the sliding surface of the ceramic body, in which the closed pores having the porosity of 3 to 30% by volume are uniformly dispersed, has the flatness of 3 μm or less and the ceramic sliding member is constructed. By doing so, it is possible to perform smooth sliding without linking for a long period of time while maintaining the perfect sealing property, so that it can be suitably used as various valves, seal rings, slider parts and the like.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a ceramic sliding member according to the present invention.

FIG. 2 is a partially enlarged view of the surface of the ceramic sliding member according to the present invention.

FIG. 3 is a diagram for explaining an experimental example using the ceramic sliding member of the present invention.

FIG. 4 is a perspective view showing a conventional facet valve, which is an example of a sliding member.

FIG. 5 is a graph showing the relationship between porosity and initial value of sliding torque.

FIG. 6 is a graph showing the relationship between the number of times of sliding and the sliding torque in the present invention and the comparative example.

FIG. 7 is a graph showing the relationship between Al ₂ O ₃ purity and wear amount in a ceramic sliding member.

FIG. 8 is a graph showing the relationship between the pore diameter and the amount of wear in the ceramic sliding member.

FIG. 9 is a graph showing the relationship between the porosity and the wear amount of a ceramic sliding member.

Claims (1)

[Claims] 1. A ceramic sliding member characterized in that closed pores having a porosity of 3 to 30% by volume are uniformly dispersed, and a flatness of a sliding surface is 3 μm or less.