JPH0285519A - Slide structure - Google Patents

Abstract

PURPOSE:To aim at enhancing the use life of a slide member by forming a silicon nitride ceramic bearing surface on a stationary member, and by forming a bearing surface made of cermet containing 40 to 90wt.% of ceramic particles and nickel or cobalt as bonding metal, on a slide member. CONSTITUTION:A bearing member 10 as a stationary member is made of silicon nitride ceramic, and a shaft sleeve 21 formed of a metal sleeve 22 formed thereon a cermet layer 23 is fitted on a rotary shaft 20. This cermet layer 23 is formed from a sintered material containing 40 to 90wt.% of ceramic particles and nickel or cobalt as bonding metal by a hot-press process, a TIG welding process or the like. Accordingly, it is excellent in wear-resistance, heat resistance, corrosion resistance, mechanical strength, and thereby it is possible to enhance the use life of the slide structure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sliding structure that constitutes a bearing portion or the like in various mechanical devices and has excellent wear resistance, heat resistance, etc., and a low coefficient of friction.

[Conventional technology]

BACKGROUND ART Conventionally, metal materials, resins, or the like have been used for rotating and sliding parts consisting of fixed members and movable members, such as bearings and rotating shafts, cylinders and pistons, etc. in various mechanical devices. Recently, efforts have been made to apply ceramics for the purpose of improving durability under harsh operating conditions such as high temperatures, high loads, or corrosive environments, and providing oil-free lubrication. For example, ceramics such as silicon nitride or silicon carbide are used on the bearing surface of the bearing and the supported surface of the rotating shaft to form a sliding surface of ceramics, or one of them is made of ceramic and the other is made of metal, such as Practical tests have also been conducted on devices in which sliding surfaces between ceramic and metal are formed using ductile cast iron or stainless steel.

[Problem to be solved by the invention]

However, sliding surfaces formed by combining ceramics are prone to scratches, bites, and resulting wear damage.
The wear resistance, which is a material characteristic unique to ceramics, cannot be fully utilized, and its useful life is short and the coefficient of friction is large. Among the combinations of ceramics, it has been reported that when a sliding surface is formed by combining silicon carbide ceramic and silicon nitride ceramic, relatively good sliding characteristics can be obtained with fewer scratches and bites. However, it is hard to say that it is practically satisfactory. Furthermore, since ceramic is a material with poor toughness compared to metal materials, a combination of ceramics has the disadvantage that it is easily damaged by mechanical shock or vibration.

On the other hand, sliding parts that are a combination of ceramic and metal, such as those that use ductile cast iron as the metal, exhibit good sliding characteristics due to the lubricating effect of graphite in the metal structure of cast iron. It has poor abrasion resistance in use and its service life is short. Stainless steel (SUS 3
04 etc.) in combination with ceramic, the wear of the sliding parts is slightly less, but there is a drawback that the coefficient of friction is large. Furthermore, in either case, since one of the materials forming the sliding portion is metal, there are significant restrictions on use in high-temperature applications.

In view of the above, it is an object of the present invention to provide a sliding structure that has excellent heat resistance and corrosion resistance, wear resistance, and a low coefficient of friction.

[Means and effects for solving the problem] In the sliding structure of the present invention, the fixed member that supports the movable member has a bearing surface made of silicon nitride ceramic, and the fixed member supported by this has a support surface made of silicon nitride ceramic. It is characterized by having a supported surface made of cermet containing 40 to 90% by weight of particles and using nickel or cobalt as a bonding metal.

FIG. 1 shows an example of the sliding structure of the present invention for a radial bearing consisting of a bearing and a rotating shaft.

(10) is a bearing, (20) is a rotating shaft, and (21) is a shaft sleeve fixed to the rotating shaft by shrink fitting or the like.

The bearing (10), which is a fixed member, is a cylindrical member made of silicon nitride ceramic sif, and the shaft sleeve (21) fitted on the rotating shaft (20) is connected to the metal sleeve (22) and its outer peripheral surface. It is a concentric two-layer laminate consisting of a cermet layer (23) formed on The rotating shaft (20) forms a sliding relationship with the bearing surface of the bearing (10) using its cermet layer (23) as a supported surface.

The fixed member having a bearing surface made of silicon nitride ceramic, such as the above-mentioned bearing, is a sintered crystal formed by a hot pressing method, a hot isostatic pressure sintering method, etc., and has good heat resistance,
It has corrosion resistance, etc., and is extremely hard with a hardness (Hv) of approximately 1500 or more, and has stable wear resistance with little uneven wear even under high load and uneven sliding conditions of moving parts such as rotating shafts. show. On the other hand, the cermet that forms the supported surface of a movable member such as a rotating shaft is ceramic, such as WC or TiC.

40 to 90 particles of ZrBz, TiBz, Cr, C, etc.
% by weight and has a composite structure with cobalt or nickel as the binding metal, it has high wear resistance, heat resistance, mechanical strength, and ceramic single-phase materials that cannot be obtained with metal single-phase materials. It has a much superior toughness value and has good impact characteristics that can withstand usage conditions where mechanical impact is applied to moving parts, and when combined with the bearing surface made of silicon nitride ceramic, it has a small coefficient of friction and little wear and damage. Forms a sliding relationship.

The above Cermet N (23) is formed by using a mixed powder of ceramic powder and bonded metal powder as a sintering raw material and using a known sintering method such as a hot pressing method or a hot isostatic pressing sintering method, or Using the mixed powder as a welding material, T
It can be formed by a welding method such as welding or powder plasma welding. In the example of FIG. 1, the cermet layer (23
) is a metal sleeve (22) separate from the movable member (20).
Although it is assumed that the cermet (23) is formed on the outer peripheral surface of the movable member (20) and then attached to the movable member (20), it is also possible to directly form the cermet (23) on the outer peripheral surface of the movable member (20) and use it as the supported surface. .

〔Example〕

Using silicon nitride ceramic as a mating material, the following wear tests and dynamic wear coefficient measurements were performed on cermet, ceramic, and metal test materials, and the results shown in Table 1 were obtained. In the table, fragrance (No.) 1 to 4 are invention examples in which silicon nitride ceramic and cermet are combined, Nα11 to 14
is a comparative example in which a silicon nitride ceramic is used as a partner material in combination with a ceramic or a metal.

(a) Wear test A ring-shaped silicon nitride ceramic (hardness: Hv1600) (A1) was attached to the rotary drive shaft (1) as shown in Fig. 2 using the rapid wear test method, and its rotating circumferential surface was measured. A plate-shaped test material (B1) is brought into sliding contact with a predetermined pressing force, and the specific wear amount (d/kg) is determined from the amount of wear on the plate surface of the test material (B1), and the silicon nitride ceramic ring (A1) is The wear depth (mm) of the circumferential surface was measured.

Pressing load: 12.4kg Friction distance: 400m Friction speed: 5B, 2cm / 5ec (b) Measurement of friction coefficient Using the precious wood friction test method, as shown in Figure 3, the rotary table (
2) Cylindrical silicon nitride ceramic (hardness: Hv16
00) (A 2 ) is fixed, the cylindrical test material (B2) on the upper end surface of the solenoid is overlapped and pressed, and the dynamic friction coefficient of the sliding surface is measured from the rotational torque of the rotary table (2). Note that the sliding surface was subjected to a polishing process (VVV) in advance and subjected to a dry test.

Pressing load: 10kg/cm" Friction speed: 10cm/see As shown in Table 1, examples of inventions that combine silicon nitride ceramic and cermet include combinations of ceramics,
And compared to the comparative example, which is a combination of ceramic and metal, the coefficient of friction is smaller and there is less wear and damage.

〔Effect of the invention〕

The sliding structure made by combining the silicon nitride ceramic and cermet of the present invention has excellent wear resistance, heat resistance, corrosion resistance, mechanical strength, etc., so it can be used, for example, in heating furnaces, internal combustion engines, agricultural machinery, and civil engineering machinery. It is useful as bearings, rotating sliding parts, seals, etc. in equipment that comes into contact with corrosive fluids, and other equipment and equipment used under harsh conditions. It can also be used without lubrication, and its sliding surface has excellent wear resistance, heat resistance, corrosion resistance, toughness, etc., resulting in an improvement in service life.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of the sliding structure of the present invention, Fig. 2 is a sectional view showing an embodiment of the sliding structure of the present invention;
This figure and FIG. 3 are explanatory diagrams of friction test procedures. 10: fixed member, 20: movable member, 21: shaft sleeve,
22: Metal sleeve, 23: Cermet layer.

Claims (1)

[Claims] 1. The fixed member has a bearing surface made of silicon nitride ceramic, and the movable member supported on this has ceramic particles 4.
1. A sliding structure having a supported surface made of cermet containing 0 to 90% by weight of nickel or cobalt as a bonding metal.