JPH09328381A - Sliding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-wear sliding device so designed that one party sliding face of ceramic sliding members subject to mutual sliding is provided wit noncrystalline hard carbonaceous film and both the void occupancy and maximum void size on the other party sliding face are specified respectively. SOLUTION: In this sliding device having two ceramic sliding members subject to mutual sliding and consisting of a ceramic stationary valve 1 and a mobile valve 2, the sliding face 1a of the stationary valve 1 is provided with noncrystalline hard carbonaceous film 3, while the sliding face 2a of the mobile valve 2 is designed to be <=6% in void occupancy and <=10μm in maximum void size. Thereby, this sliding device exhibits excellent sliding performance even without the use of any lubricating oil and is ensured to use favorably over a long period with reduced wear. Besides, if the sliding face 2a is constituted of a composite sintered compact (e.g. Cermet) made up of hard phase consisting of at least one kind among metal oxides, carbides and nitrides and metallic phase such as of Ni or Co, the sliding performance of this device can be further improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to bearings such as bearings, guide rails, air slides and spindles, and various sliding devices such as seal members and valves.

[0002]

2. Description of the Related Art Since ceramics have high hardness and excellent heat resistance and wear resistance, their use as sliding members for various industrial machines has been studied.

Further, recently, a sliding member in which an amorphous hard carbon film is formed by using ceramics as a base material has been proposed (see Japanese Patent Laid-Open Nos. 3-223190 and 5-296248). For example, in a valve device such as a Fawcett valve, valve bodies that slide with each other are formed of ceramics, and the sliding surface of the ceramic valve body is made of amorphous hard material having a thickness of about 0.2 to 2 μm by a CVD method or the like. By forming the carbon film, it is possible to configure a sliding device that does not use lubricating oil or the like. Since this amorphous hard carbon film is excellent in wear resistance and slidability, it is possible to reduce the amount of mutual wear and to maintain good sliding characteristics without causing linking or the like for a long period of time.

[0004]

However, in a sliding device in which an amorphous hard carbon film is formed on one sliding surface and the other sliding surface is made of ceramics, the sliding surface on the ceramic side is Depending on the surface condition, the amorphous hard carbon film is easily worn, and the amorphous hard carbon film having a thickness of about 0.2 to 2 μm is easily worn or peeled off. Then, when the amorphous hard carbon film disappears, there is a disadvantage that the ceramics slide with each other and the abrasion rapidly progresses.

[0005]

SUMMARY OF THE INVENTION Therefore, according to the present invention, an amorphous hard carbon film is formed on one sliding surface of ceramic sliding members that slide on each other, and the other sliding surface is occupied by a void. The sliding device is characterized by a maximum void diameter of 10 μm or less at a rate of 6% or less.

In the present invention, the sliding member on the opposite side of the amorphous hard carbon film is a composite sintered body of a hard phase and a metal phase, which is made of one or more kinds of metal oxides, carbides and nitrides. It is characterized by being formed in.

That is, it is generally unavoidable that minute voids exist on the surface of ceramics, and voids also exist on the sliding surface of the ceramic sliding member on the other side of the amorphous hard carbon film. And as a result of various experiments by the present inventors,
Abrasion of the amorphous hard carbon film at the edges of voids existing on the sliding surface of the ceramic sliding member, and the larger the number of voids, the greater the effect of abrading the amorphous hard carbon film. I understood.

Therefore, if the occupation ratio of voids existing on the opposite sliding surface of the amorphous hard carbon film is 6% or less and the maximum void diameter is 10 μm or less, the wear of the amorphous hard carbon film is minimized. We have found that it can be suppressed to the limit.

Moreover, although the slidability with the amorphous hard carbon film varies depending on the type of ceramics and the state of voids that form the sliding member, both members can be measured by measuring the friction coefficient by the ball-on-disk test. Of the friction coefficient of 0.30 under the conditions described later.
By making the following combinations, a particularly excellent sliding device can be obtained.

Further, as a ceramic sliding member on the other side of the amorphous hard carbon film, metal oxides, carbides,
It has been found that when a composite sintered body of a hard phase made of one or more kinds of nitrides and a metal phase such as Ni or Co is used, the slidability is particularly excellent and the mutual wear amount can be reduced. The composite sintered body includes cermet and cemented carbide, and the ceramics in the present invention also includes these composite sintered bodies.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a sliding device of the present invention will be described below.

The facet valve shown in FIG. 1 has a ceramic fixed valve body 1 and a movable valve body 2 as two sliding members, and the sliding surface 1a of the fixed valve body 1 is made of amorphous hard carbon. The film 3 is formed. On the other hand, the sliding surface 2a of the movable valve body 2
Although it remains ceramics, this sliding surface 2a is a surface with few voids, with a void occupancy rate of 6% or less and a maximum void diameter of 10 μm or less.

Then, the sliding surfaces 1a, 2a are brought into contact with each other and slid to each other so that the fluid passages 1b, 2
The flow rate of the fluid can be adjusted by opening and closing b.
At this time, since the amorphous hard carbon film 3 having excellent slidability and wear resistance is formed on the sliding surface 1a of the fixed valve body 1, one sliding surface 2a is a surface with few voids. The amorphous hard carbon film 3 is not worn. Therefore, when sliding on each other, it shows excellent slidability without the use of lubricating oil,
It can be used favorably for a long period of time by reducing the amount of wear. In addition, the fixed valve body 1 which is the base material of the amorphous hard carbon film 3
Since the amorphous hard carbon film 3 is formed of ceramics and is hard to be deformed, the amorphous hard carbon film 3 can be prevented from peeling and the weight can be reduced.

In addition, as shown in FIG. 2 according to another embodiment of the present invention, a bearing member 11 and a shaft member 1 are used as two sliding members.
In the bearing device having 2, the bearing member 11 is formed of ceramics, the amorphous hard carbon film 13 is formed on the sliding surface 11a, and the one shaft member 12 is formed of ceramics, and the sliding surface thereof is formed. 12a has a void occupancy rate of 6% or less and a maximum void diameter of 10 μm or less, and is a surface with few voids.

By sliding the sliding surfaces 11a and 12a with each other, the bearing member 11 can support the movement of the shaft member 12 in the rotational direction and the linear direction.
At this time, while forming the amorphous hard carbon film 13,
Since the mating sliding surface 12a is a surface with few voids, it exhibits excellent slidability and reduces the amount of wear.
It can be used well for a long time. Further, by forming the bearing member 11 which is the base material of the amorphous hard carbon film 13 from ceramics, the amorphous hard carbon film 13 can be prevented from peeling because it is difficult to deform.

The sliding device of the present invention may be any device as long as it operates by sliding a plurality of members on a sliding surface, and in addition to the above, bearings, guide rails, air slides, spindles, etc. It can be used for bearing devices, seal devices, and various sliding devices such as valves.

The fixed valve body 1, the movable valve body 2, the bearing member 1
1. As the ceramics constituting each member such as the shaft member 12 and the like, one or more of alumina, zirconia, silicon carbide, silicon nitride, aluminum nitride, titanium carbide and the like are main components, and sintering aids are added to these main components. A sintered body containing a predetermined amount of subcomponents such as an agent is used. For example, for alumina, at least one of CaO, SiO ₂ , and MgO, and for silicon carbide, C, B, B ₄ C, and Al.
₂ O ₃ , Y ₂ O _{3 and the} like, and oxides and nitrides of elements of groups 2a and 3a of the periodic table are added as sintering aids to silicon nitride, and Y ₂ O is added to zirconia. ₃ , C
A stabilizer such as aO or MgO may be added.

Further, as a ceramic constituting each member, a composite sintered body of a hard phase composed of one or more kinds of metal oxides, carbides and nitrides and a metal phase such as Ni or Co can be used. And in the sliding device of the present invention,
Sliding surface 2 which is the other side of the amorphous hard carbon films 3 and 13
If a and 12a are made of such a composite sintered body, the slidability can be particularly enhanced.

As such a composite sintered body, for example, T
A cermet that is a composite sintered body of a hard phase such as iC and TiN and a metal phase such as Co and Ni, or a cemented carbide that is a composite sintered body of a hard phase formed of WC and a metal phase formed of Co. To use. Incidentally, the ceramics in the present invention,
These cermets and cemented carbides are also included.

Further, when the sliding member on the opposite side of the amorphous hard carbon films 3 and 13 is formed of these ceramics, the raw material powder is made into fine powder and fired so as to obtain a dense sintered body. It is necessary to devise conditions for polishing the sliding surfaces 2a and 12a so that the void occupancy rate is 6% or less and the maximum void diameter is 10 μm or less.

The void occupancy rate and the maximum void diameter of the sliding surfaces 2a and 12a can be measured by analyzing the sliding surfaces 2a and 12a with an image analyzer.

On the other hand, the sliding surfaces 1a and 11a of the above sliding device
The amorphous hard carbon films 3 and 13 formed on the substrate are also referred to as other names such as amorphous carbon, diamond-like carbon, DLC, and the like.
It is formed by the VD method, the PVD method or the like, and has a film thickness of 0.2 to 2
It is preferably set to μm.

Further, in such a sliding device, if the types of ceramics on the other side that slide on the amorphous hard carbon films 3 and 13 are different, the sliding characteristics are different. Therefore, in the present invention, it was found that the sliding characteristics can be evaluated by the friction coefficient by the ball-on-disk test.

Here, as shown in FIG. 3, the ball-on-disk tester is a tester in which a ball 21 is brought into point contact with the disk 22 and a disk is rotated under a constant load. .

The coefficient of friction in the ball-on-disk test according to the present invention is measured as follows.

First, a ball 21 having the same material and surface condition as the original sliding member is produced by cutting out from the sliding member on the opposite side of the amorphous hard carbon film 3, 13 in the sliding device. Disk 22 formed with an amorphous hard carbon film
Prepare Then, a load of 1 kg is applied to the ball 21, the disk 22 is rotated at a peripheral speed of 5 m / s, and the friction coefficient when both are slid is measured.

The coefficient of friction thus measured is 0.3.
By using a combination of materials that is 0 or less, the sliding characteristics are extremely excellent, the mutual wear is small, and it can be used satisfactorily for a long period of time.

[0028]

EXAMPLES Experimental Example 1 First, an experiment for confirming the effect of an amorphous hard carbon film was conducted using a ball-on-disk tester.

Using the tester shown in FIG. 3, a diameter of 40 mm
As shown in Table 1, the disk 22 of the above is used as a simple substance of various ceramics, and an amorphous hard carbon film (DLC) on the ceramics.
Was formed with a thickness of 2 μm. The method for forming the amorphous hard carbon film is benzene (C ₆ H
₆ ) An ion plating method was adopted in which carbon ions obtained by ionizing gas with a filament were deposited on the surface of the disk 22 by an ion accelerator.

The ball 21 has a diameter of 9.5 mm and is made of a metal material (SUJ2). The ball 21 is pressed against the disk 22 with a load of 1 kg, and the peripheral speed of the disk 22 is 5 m.
/ S, temperature 20 ° C, humidity 50-60%, the test for 30 minutes was performed. After that, the amount of wear of the ball 21 and the disk 22 and the friction coefficient between them were measured.

As shown in Table 1, the results obtained by forming an amorphous hard carbon film on a ceramic base material (Nos. 7 to 1).
In 3), it was found that both the wear amount of the balls 21 and the disk 22 was small and the friction coefficient was low.

No. No. 14 is a metal material (SKH) on which an amorphous hard carbon film is formed, and the amorphous hard carbon film peeled off during the test. Therefore, the base material of the amorphous hard carbon film is preferably ceramics.

[0033]

[Table 1]

Experimental Example 2 Next, the same experiment as described above was carried out, assuming that the disk 22 had an amorphous hard carbon film formed on alumina ceramics and the material of the ball 21 was variously changed.

As shown in Table 2, the balls 21 made of ceramics (Nos. 15 to 20) have a small amount of wear of the balls 21 and the disk 22, and have a low friction coefficient of 0.30 or less. Recognize.

That is, it is understood that the sliding device of the present invention, which is composed of the combination of the amorphous hard carbon film and the ceramics, can reduce the mutual wear and the friction coefficient.

Particularly, as the material of the balls 21, those using cermet or cemented carbide which is a composite sintered body of a hard phase and a metal phase (Nos. 19 and 20) have a friction coefficient of 0.10 or less. It can be seen that it is low and has excellent slidability.

[0038]

[Table 2]

Experimental Example 3 Next, in the above Experimental Example 2, the material of the balls 21 was alumina, and firing conditions and polishing conditions were changed to prepare those having different void occupancy ratios and maximum void diameters on their surfaces.
The same experiment as above was performed.

Here, the void occupancy rate is the ratio of the void area confirmed when the surface of the ceramic forming the ball 21 is observed, and the void occupancy rate (%) = (total void area / observed area) × 1
It is defined by 00. Specifically, using an image analyzer (Luzex), the magnification is 400 times and the evaluation area is 2.32 × 10.
It was calculated by observing 10 points per sample at ⁻⁵ μm ² and a contrast of 25%.

The maximum void diameter is the maximum diameter of voids in the above observation range, and was similarly measured using an image analyzer.

The results are shown in Table 3. From this result, it can be seen that the wear amount of the ball 21 and the disk 22 increases as the void maximum diameter and the void occupancy rate increase. And the void occupancy rate exceeds 6%, or the maximum void diameter exceeds 10 μm (No. 30 to 34)
, The amorphous hard carbon film of the disk 22 was peeled off.

On the other hand, a void occupancy ratio of 6% or less, and a maximum void diameter of 10 μm or less, an embodiment of the present invention (N
o. 24 to 29), the amorphous hard carbon film on the disk 22 was not peeled off, the amount of wear of the balls 21 and the disk 22 was small, and the friction coefficient was also low. Therefore, if the void occupancy rate is 6% or less and the void maximum diameter is 10 μm or less on the sliding surface of the other party that slides with the amorphous hard carbon film,
It can be seen that the amorphous hard carbon film can be preferably used without peeling off.

[0044]

[Table 3]

By the way, in Table 3, the amorphous hard carbon film peels off when the friction coefficient between the ball 21 and the disk 22 exceeds 0.30, and is amorphous when the friction coefficient is 0.30 or less. It can be seen that peeling of the hard carbon film can be prevented.

Also, in Table 2 of Experimental Example 2 described above, it can be seen that the friction coefficient of the comparative example with large wear exceeds 0.30, and the friction coefficient of the present invention example is 0.30 or less. .

Therefore, there is a correlation between the coefficient of friction and the amount of wear, and if the coefficient of friction under the conditions of the above experimental example is set to 0.30 or less, peeling and wear of the amorphous hard carbon film will occur. It can be seen that this can be prevented.

[0048]

As described above, according to the present invention, the amorphous hard carbon film is formed on one sliding surface of the ceramic sliding members which slide on each other, and the other sliding surface is voided. By configuring the sliding device so that the occupancy rate is 6% or less and the maximum void diameter is 10 μm or less, the amount of mutual wear can be reduced and good sliding characteristics can be maintained for a long period of time.

According to the present invention, the sliding member on the opposite side of the amorphous hard carbon film is composite-baked with a hard phase composed of one or more kinds of metal oxides, carbides and nitrides and a metal phase. By forming the united body, it is possible to particularly reduce the amount of wear and improve the sliding characteristics.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a facet valve which is an example of a sliding device of the present invention.

FIG. 2 is a schematic sectional view of a bearing device which is an example of a sliding device of the present invention.

FIG. 3 is a perspective view showing a ball-on-disk tester.

[Explanation of symbols]

 1: Fixed valve body 1a: Sliding surface 2: Movable valve body 2a: Sliding surface 3: Amorphous hard carbon film 11: Bearing member 11a: Sliding surface 12: Shaft member 12a: Sliding surface 13: Amorphous Quality hard carbon film 21: Ball 22: Disc

Claims (2)

[Claims] 1. A ceramic sliding member which slides on each other, wherein an amorphous hard carbon film is formed on one sliding surface and the other sliding surface has a void occupancy of 6% or less and a maximum void diameter of 10 μm.
A sliding device characterized by the following. 2. The sliding member on the opposite side of the amorphous hard carbon film is formed of a composite sintered body of a hard phase and a metal phase, which is composed of one or more kinds of metal oxides, carbides, and nitrides. The sliding device according to claim 1, wherein: