JP2001220605A - Sliding member excellent in wear resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the frictional sliding characteristics of a sliding member in a bearing device forming sliding relation with ceramics or the like. e.g. a sliding member in the bearing part of the blade shaft of a drain pump or the like. SOLUTION: This sliding member is combined with a counter part material having a sliding face composed of silicon nitride ceramics (5). As the sliding face with the counter part material, a hard layer (1) composed of a metal matrix and hard particles of 40 to 75 vol.% is contained. As the constitution of the sliding member on the shaft side (10), the form in which a double-layered member (3) composed of the metal matrix and the hard layer is fitted to a rotary shaft (4) is adopted. In the hard layer, as the hard particles, carbides (such as WC and TiC), borides (such as MoB and TiB) or nitrides (such as TiN and CrN) are used, and, as the matrix metal, a Co base alloy, an Ni base alloy, a Ti base alloy or the like are used. The hard layer is formed as a sintered body by a hot isostatic pressing method or as a build-up weld layer by powder plasma welding or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a bearing member for various industrial machines, a bearing member for drainage / pumping pumps, a sliding member such as a valve guide for an internal combustion engine, and a component member of a resin kneading / molding machine. The present invention relates to a sliding member useful as a constituent material of a sliding portion such as a cylinder, a screw, and a nozzle.

[0002]

2. Description of the Related Art A sliding member such as a shaft and a bearing member constituting a bearing device requires abrasion resistance of a sliding surface, strength and toughness capable of withstanding load stress, environmental temperature change, and the like, and thermal shock resistance. I do. In a bearing device in a severe sliding / friction environment, a metal alloy such as a cemented carbide (Co-based alloy)
There is known a bearing structure in which a sliding surface is formed of hard particles of not less than% by volume) and silicon carbide ceramics is applied to a bearing side that supports the sliding surface to provide wear resistance. The sliding member having this combination has good wear resistance, but both members have poor toughness and are liable to crack or break due to mechanical or thermal stress. As an improvement, it has been proposed to replace silicon carbide ceramics on the bearing side with silicon nitride.

[0003]

Since silicon nitride ceramics have a high fracture toughness and excellent thermal shock characteristics, they can be used as one of the sliding members of a bearing device to provide thermal and mechanical properties. Stability against mechanical impact can be enhanced. However, as compared with silicon carbide ceramics, the sliding members made of cemented carbide are inferior in wear resistance. Further, even if the ceramic is made tough, there remains a problem that the cemented carbide of the sliding member facing the ceramic has poor toughness and is easily cracked by thermal stress or impact. The present invention has been made to solve the above problems.

[0004]

SUMMARY OF THE INVENTION A sliding member according to the present invention is a sliding member combined with a mating member having a sliding surface made of silicon nitride ceramics, and a metal matrix is formed in a region facing the mating member. A hard layer composed of 40 to 75% by volume of hard particles is formed.

[0005] The sliding member of the present invention is provided with a multi-layer member comprising a metal base and a hard layer laminated on the surface thereof, at a portion facing a mating material having a sliding surface made of silicon nitride ceramics. In some cases.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The metal material which is the matrix of the hard layer of the sliding member of the present invention is selected from Co-based alloys, Ni-based alloys in view of seizure resistance, high-temperature strength, corrosion resistance (for example, corrosion resistance against seawater), and the like. And a Ti-based alloy are preferred. These alloys may be Cr, Mo, B, Ni, and F as alloying elements for further improving physical properties such as mechanical strength and corrosion resistance.
A chemical composition containing an appropriate amount of one or more of e, W, Al, V and the like is provided. Further, when the matrix has high hardness (preferably HRC 20 or more), it is advantageous because the compounding amount of the hard particles as the reinforcing material can be adjusted to a small amount.

Specific examples of the metal matrix include alloys having the following chemical compositions (all element contents are% by weight). [Co-based alloy] Cr: 15 to 35%, Mo: 5 to 20%, B: 1 to 5
%, Fe: 3% or less, Ni: 5% or less, C: 3% or less,
Si: 2% or less, balance substantially Co. Cr: 20 to 40%, Ni: 3% or less, W: 4 to 20
%, Fe: 5% or less, C: 2.5% or less, Si: 2% or less, the balance substantially Co.

[Ni-based alloy] Cr: 5 to 30%, B: 5% or less, Fe: 5% or less,
C: 2.0% or less, Si: 10% or less, balance substantially N
i. [Ti-based alloy] Al: 2 to 10%, V: 1 to 10%, balance substantially T
i.

[0009] The hard particles, which are the dispersed phase of the hard layer, are made of carbide.
Type, boride type, nitride type, silicide type, oxide type etc.
Ceramics. In particular, carbides, borides, nitrides
Material ceramics have high hardness and good slidability.
It is preferable because it is excellent. As an example of the carbide system,
WC, W₂C, TiC, NbC, VC, Mo₂C, Cr
₃C₂, TaC, ZrC, etc.
B, TiB₂, CrB, VB_Two , NbB₂, TaB₂,
Examples of nitrides such as WB include TiN and CrN.
It is. The hard particles in the hard layer are mixed with different component particles.
Is also good.

The content of the hard particles must be 40 to 75% by volume. If the content is less than 40% by volume, the sliding wear resistance to the mating material (silicon nitride ceramics) is insufficient, and the wear resistance in a usage environment in contact with a slurry containing earth and sand, such as a bearing part of a drainage pump, is secured. Can not do it. If the upper limit is 75% by volume, if it exceeds this, the toughness of the hard layer itself will be poor, the stability against mechanical and thermal shocks will be impaired, and the aggressiveness against the partner material (silicon nitride ceramics) will increase. This is because the stability of the sliding structure is impaired.

[0011] The multi-layer member (1: hard layer, 2: metal substrate) in the sliding member to which the multi-layer member (described later, FIG. 1) is mounted.
The metal base material is appropriately selected according to the use and use environment conditions of the sliding member. Stainless steel and Ti-based alloys (described above) have excellent corrosion resistance to seawater and the like, and are preferred as constituent materials of sliding members constituting bearing devices such as drainage pumps. In stainless steel, especially austenitic (for example, SUS304,
SUS316), duplex stainless steel (for example, SUS329J1) and the like are preferable. The configuration of the hard layer in the multilayer member is the same as described above.

The hard layer of the sliding member of the present invention is obtained by uniformly mixing a metal powder as a matrix and a hard particle powder as a dispersed phase particle with a ball mill or the like to obtain a raw material powder, and hot isostatic pressing. It is formed as a sintered body by a method (HIP method) or the like, or as a weld overlay (for example, powder plasma weld overlay).

[0013] The HIP treatment is carried out by holding under pressure and heat for an appropriate time. Processing temperature is about 900-12
00 ° C. and the pressure are appropriately set in the range of about 70 to 150 MPa. The processing time is about 1 to 10 hours.

For the welding overlay method, for example, powder plasma welding overlay method is applied, and a metal powder is melted by plasma arc heat while supplying a raw material powder (a mixture of a metal powder and a hard particle powder) to the surface of a base material. A hard layer is formed as a weld bead by suspending and solidifying hard particles in a molten pool.

When the HIP molding method is compared with the welding overlay method, the HIP molding method has a lower processing temperature than the welding overlay method and dissolves hard particles (changes and disappearance of the particle diameter of the hard particles and the accompanying hardening). There is no change in the volume percentage of the hard particles in the layer and no change in the composition of the metal matrix), and the effect of strengthening the dispersion of the hard particles can be effectively exhibited. In addition, since there is little melting / dilution (component change) at the lamination interface, selection of material types for metal matrix and hard particles
The degree of freedom in combination and the like is large, and component design is easy.

FIG. 1 shows an example of a multilayer member for constituting the sliding member of the present invention. 1 is a hard layer and 2 is a metal substrate. The multilayer member (3) has a sleeve shape in which a hard layer (1) is laminated on a circumferential surface of a cylindrical metal base material (2). used. The multilayer member shown in the figure has a hard layer (1) on the outer peripheral surface side of the metal base material (2). Is provided.

When the multilayer member (3) is manufactured by the HIP method, a capsule (made of mild steel) is filled with a metal base material and a hard layer forming material, degassed and sealed, and subjected to HIP processing. After the treatment, the capsule is removed by machining or the like to obtain a multilayer member (3) composed of the metal substrate (2) and the hard layer (1) as a sintered body. The interface between the hard layer (1) and the metal substrate (2) is firmly joined by solid phase diffusion during HIP processing.

FIG. 2 shows an example in which a bearing device (for example, a bearing portion of a drainage pump) is formed by applying the sliding member of the present invention. Reference numeral 10 denotes a rotating shaft side sliding member, and reference numeral 20 denotes a fixed side sliding member (bearing). The sliding member (10) on the rotating shaft side is attached to the rotating shaft (4) by the multilayer member (sleeve) (3) of FIG.
Is configured. Bearing (20)
Has a sliding surface made of silicon nitride ceramics (5) and forms a sliding relationship with the hard layer (1) of the rotating shaft side sliding member (10).

FIG. 3 shows another example of a bearing device to which the sliding member of the present invention is applied. In this example, the rotation axis (4)
A hard layer (1) is formed on the circumferential surface of the rotary sliding member (1).
0) and has a sliding relationship with a counterpart material (silicon nitride ceramics on the bearing side). The rotary shaft side sliding member (10) is provided with a concave groove (7) surrounding the circumferential surface at a required portion of the rotary shaft (4), and a hard layer (1) is formed in the groove. . The hard layer (1) is formed as a sintered body by the HIP method or as a weld overlay.

The sliding member of the present invention is a bearing member for various industrial machines, a bearing member for drainage / pumping pumps, a sliding member such as a valve guide for an internal combustion engine, and a constituent member of a resin kneading / molding machine. It is suitably used as a sliding member such as a cylinder, screw, nozzle and the like.

[0021]

EXAMPLE A test material is prepared by a HIP method using a mixed powder obtained by mixing a metal powder as a matrix and hard particles as a reinforcing material by a ball mill and a metal substrate.

(1) Metal matrix (element content: weight%) (Co alloy 1) Cr: 15.50, Mo: 5.20, B: 0.72, Ni: 1.03, Fe: 0.94, C: 1.1
4, Si: 0.33, Co: Bal HRC = 53 (Co alloy 2) Cr: 31.35, W: 8.39, Ni: 1.98, Fe: 2.06, C: 1.71, Si: 1.2
7, Co: Bal HRC = 43 (Ni alloy) Cr: 15.77, B: 2.70, Fe: 3.68, C: 0.64, Si: 4.72, Ni: Bal HRC = 51 (Ti alloy) Al: 6.12, V: 4.23, Ti: Bal HRC = 13

(3) Grade and particle size of hard particles W ₂ C: 100-200 μm TiC: 75-150 μm NbC: 75-150 μm

(4) HIP treatment The raw material powder for forming the hard layer and the metal substrate are encapsulated (made of mild steel).
And subjected to HIP treatment. After the treatment, the capsule is removed by machining to take out the test material. Temperature: 1100 ° C Pressure: 110 MPa Processing time: 2Hr

A test piece was prepared from the test composite material and subjected to the following tests. [Wear test] Evaluation test of wear resistance using ceramics as the mating material. According to Ogoshi quick wear tester. The test piece is pressed against a counterpart material (rotating disk), and the wear reduction (mm ² / N) on the test piece surface is calculated from the depth and width of the wear flaws generated on the test piece surface. Counterpart material: Silicon nitride ceramics Peripheral speed: 3.38 m / s Friction distance: 400 m Load: 61 N

[Sliding Test] The friction coefficient (μ) is measured by a friction and wear tester (“TRAS-300” manufactured by Takachiho Seiki Co., Ltd.). In this sliding test, the seizure resistance of the sliding surface is evaluated (seizure state: abnormal torque and a state in which the sliding device is stopped). Counterpart material: silicon nitride or silicon carbide ceramics Load: 20N Rotational speed: 500 rpm Test time: 60 minutes

[Bending strength] Test method: Three-point bending test (JIS B1601) Specimen size: 3 x 4 x 40, mm Span distance: 30 mm Test temperature: room temperature

[0028]

[Table 1]

Table 1 shows the measurement results of the component composition and physical properties of each test material. Comparative Example No. 101 is an example in which the wear resistance of the hard layer is good but silicon carbide ceramics is used as a mating material. The friction coefficient of the sliding surface is high, and the seizure resistance is poor. In No. 102, the content of the hard particles in the hard layer was insufficient, and the wear resistance was poor. In addition, No. 103 has a very low flexural strength due to an excessive content of hard particles in the hard layer (the test piece fractured during the friction coefficient measurement test due to insufficient strength). No.104
Is an example of a conventional sliding structure combining a cemented carbide (G5) and silicon nitride ceramics. The sliding surface has good abrasion resistance, but has a high coefficient of friction and has a good seizure in a short time. I'm coming.

On the other hand, the invention examples are excellent in abrasion resistance and high strength, have good sliding characteristics with silicon nitride ceramics as a mating material, stably maintain low frictional properties, and are resistant to burning. Excellent stickiness.

[0031]

The sliding member of the present invention is excellent in wear resistance and strength, etc., and has good wear sliding characteristics using silicon nitride ceramics as a mating material. Therefore, as a material for bearing parts and other sliding parts of drainage pumps provided with severe sliding / frictional environment, for example, the stability of the sliding function is enhanced, the durability is improved, and the maintenance is greatly reduced. To bring.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a multi-layer member constituting a sliding member of the present invention.

FIG. 2 is a front sectional view showing an example of a bearing device in which the sliding member of the present invention is incorporated.

FIG. 3 is a front sectional view showing another example of the bearing device in which the sliding member of the present invention is incorporated.

[Explanation of symbols]

 1: Hard layer 2: Metal substrate 3: Multi-layer member 4: Rotating shaft 5: Silicon nitride ceramics 10: Sliding member 20: Sliding member on the other side

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hiroyuki Inoue 1-1-1, Nakamiya Oike, Hirakata City, Osaka Prefecture Inside Kubota Hirakata Factory (72) Inventor Yoshinobu Ogawa 1-1-1, Nakamiya Oike, Hirakata City, Osaka Prefecture No. 1 F-term in the Kubota Hirakata Plant (reference) 3H022 BA06 CA04 CA13 CA51 CA53 DA13 DA16 4K018 AA06 AA07 AA10 AB02 AB03 AB04 AD01 AD10 AD11 EA13 JA27 KA02 KA05

Claims (7)

[Claims] 1. A sliding member to be combined with a mating member having a sliding surface made of silicon nitride ceramic, wherein a hard layer made of a metal matrix and 40 to 75% by volume of hard particles is provided in a region facing the mating member. Having a sliding member. 2. A sliding member combined with a mating member having a sliding surface made of silicon nitride ceramics, wherein a hard layer made of a metal matrix and 40 to 75% by volume of hard particles is laminated on a surface of a metal substrate. A sliding member in which the formed multilayer member is mounted on a portion facing a mating material. 3. The sliding member according to claim 2, wherein the metal substrate of the multilayer member is stainless steel or a Ti-based alloy. 4. The hard particles are one or more kinds of particles selected from carbide, boride or nitride ceramic particles, and the metal matrix is a Co-based alloy, Ni
The sliding member according to any one of claims 1 to 3, wherein the sliding member is a base alloy or a Ti base alloy. 5. The sliding member according to claim 1, wherein the hard layer is a hot isostatic pressing sintered body. 6. The sliding member according to claim 1, which is a movable member. 7. The sliding member according to claim 6, which is a blade shaft of a pump.