JP2002069563A - Composite material for sliding member having excellent corrosion resistance and wear resistance and sliding member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite material/sliding member formed with a sliding face having excellent wear resistance (ceramics sliding wear resistance and slurry wear resistance) and corrosion resistance (salt water resistance, acid corrosion resistance or the like) and, e.g. useful as the sliding member of the rotary shaft of a drainage pump. SOLUTION: This composite material is composed of a matrix formed with a metal having a pitting potential of >=400 mV and hard grains occupying 40 to 80 wt.% and has a pitting potential of <=400 mV. The matrix is composed of an Ni based alloy, a Ti based alloy or the like, and the hard grains are, e.g. composed of the carbides, borides, silicides or oxides of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W. Particularly, the carbides of Ti, Zr, Hf, V, Nb, Ta or the like are suitable. The sliding member is produced as a laminated body in which, e.g. a hollow cylindrical body is used as a base member, and a surface layer (a hot isostatic press sintered layer, a build-up welded layer or the like) composed of the composite material is formed on the side used as the sliding face.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite material useful as a material for forming a sliding surface of a sliding member of various equipment and devices, particularly a sliding member which is required to have corrosion resistance to salt water, acid, etc. in addition to abrasion resistance. The present invention relates to a sliding member having a sliding surface made of a material and a composite material.

[0002]

2. Description of the Related Art Co-based cemented carbide (WC-12Co) is used as a material for forming a sliding surface of a sliding member requiring high wear resistance.
Etc.) are widely used. For example, in a drain pump, it has been proposed that the sliding surface of a blade shaft is formed of a Co-based cemented carbide and a bearing is formed by using ceramic as a mating material (bearing material) (Japanese Patent Publication No. 63-67048). Gazette). Co-based cemented carbide has outstanding wear resistance, but poor salt water resistance. For this reason, for example, when used as a shaft member of a drain pump in a use environment exposed to seawater, the soundness of the sliding surface is easily impaired, and there is a problem in durability.

[0003] Structural materials used for saltwater-resistant applications include austenitic stainless steel (for example, JIS G43).
03 SUS304, SUS316L) and Ni-based alloy “Hastelloy C alloy” (14-17% Cr, 15-17% Mo, 3-5% W, 4-7% Fe, Ni
"Inconel 625 alloy" (20-23% Cr, 8-10% Mo,
3.15-4.15% (Nb + Ta), 5% ≧ Fe, Ni remaining) are known.
However, all of these materials have poor abrasion resistance, and particularly when used as sliding members exposed to seawater mixed with silica sand, etc., reduce the abrasion due to collision and contact of suspended particles (sand and sand erosion). And the stability as a sliding member is lacking.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems relating to a sliding member, and comprises a blade shaft of a drainage pump which comes into contact with seawater containing hard particles such as silica sand, and a bearing thereof. A composite material for forming a sliding surface with improved resistance to severe wear and corrosive action, and a surface made of the composite material, for a sliding portion component of various devices and devices, including a manual portion. A sliding member having a layer is provided.

[0005]

The composite material for a sliding member according to the present invention is a composite comprising a matrix formed of a metal having a pitting potential of 400 mV or more and hard particles occupying 40 to 80% by weight. And has a pitting potential of 400 mV or more. The sliding member of the present invention has a surface layer made of the above-described composite material formed in a region serving as a sliding surface.

The pitting potential defined in the present invention is JIS G05
77 (1981), which is measured in accordance with the provisions of "Method of measuring pitting potential of stainless steel". Measurement conditions were artificial seawater (3.5% sodium chloride solution), liquid temperature of 25 ° C., potential sweep rate of 20 mV / min, Ar degassing, and current density of 100 μA / cm ^2.
The potential (Vc'100) at is defined as the pitting potential.

The pitting potential of the composite material of the present invention is 4
The austenitic stainless steel [JIS G43], which is defined as a typical material for salt water resistant use, is defined as 00 mV or more.
03SUS316L] (its pitting potential is about 370 mV) as an effect of a high potential (400 mV) to secure improved salt water resistance in actual use of the sliding member. Advantageous Effects of the Invention The present invention provides an excellent effect of being a composite containing hard particles as a dispersed phase (reinforcing material), such as excellent abrasion resistance (earth and sand abrasion erosion resistance) to a use environment in contact with a slurry containing silica sand or the like. ing.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the composite material of the present invention, a matrix is formed of a metal material having a pitting potential of 400 mV or more as a necessary condition for securing salt water resistance. The material type of the matrix is not particularly limited as long as it satisfies this condition, but specifically, is appropriately selected from a Ni-based alloy and a Ti-based alloy. Preferred examples thereof include alloys having the following chemical compositions. % Indicating the alloy composition is based on weight.

[Ni-based alloy] Ni-based alloy 1 Cr: 14 to 17%, Mo: 15 to 17%, W: 3 to 5
%, Fe: 4 to 7%, balance substantially Ni. Ni-based alloy 2 Cr: 20 to 23%, Mo: 8 to 10%, Nb + Ta:
3.15 to 4.15%, Fe: 5% or less, balance substantially Ni. Ni-based alloy 3 Cr: 20-50%, one or two of Mo and W: 10
30% (the total amount in the case of two kinds), the balance being substantially Ni. [Ti-based alloy] Al: 2 to 10%, V: 1 to 10%, balance substantially T
i.

Various ceramic particles such as carbide, boride, nitride, silicide and oxide are used as the hard particles as the dispersed phase (reinforcing material) of the composite material of the present invention. In particular, carbides, borides, and nitrides are suitable because they have high hardness and excellent slidability. Examples of such ceramics include WC, W ₂ C, TiC, and Nb in carbides.
C, VC, Mo ₂ C, Cr ₃ C ₂ , TaC, ZrC, etc.
In the _{boride, MoB, TiB 2, CrB,} VB 2, Nb
B ₂ , TaB ₂ , WB and the like.
TiN, CrN and the like can be mentioned.

The pitting potential of a composite material (composite of a metal matrix and hard particles) is generally lower than the pitting potential of the metal forming the matrix, and the pitting potential decreases with an increase in the blending amount of the hard particles. There is a tendency. Therefore, the compounding amount of the hard particles is limited to a range in which the pitting potential (400 mV or more) of the composite material is secured. In addition, Ti-based, Zr
And Hf-based hard particles have a small decrease in the pitting potential of the composite material and allow a relatively large amount of compounding.
The hard particles of the Ti-based or Ta-based show a peculiar tendency that the pitting potential of the composite material is increased with the compounding thereof.
Therefore, it is particularly suitable as the dispersed phase particles of the composite material of the present invention.

Regarding the content of hard particles, the lower limit is 40.
The reason for specifying the weight% is to clarify the effect of improving the wear resistance by the dispersion strengthening action. The wear resistance is enhanced with increasing the amount, but if the amount is excessively increased, embrittlement and insufficient pitting potential occur. Therefore, the upper limit is 80% by weight. When V, Nb, Ta-based hard particles are used, the effect of increasing the pitting potential of the composite material is obtained. However, when the compounding amount exceeds 80% by weight, the ductility of the composite material is reduced. Therefore, when these hard particles are used, the upper limit is 80% by weight.

The sliding member having the surface layer made of the composite material of the present invention is subjected to hot isostatic pressing (HIP).
As shown in FIG. 1 or as a press-formed body (sintered body) or a suitably shaped metal member (the figure is an example of a hollow cylindrical body) (2) as a base member, It is produced as a laminate having a surface layer (1) made of a composite material on the side (outer peripheral surface in the figure). Surface layer to be the sliding surface (1)
Is formed as a sintered body layer by a HIP process or a weld overlay as described later.

In the case of manufacturing a sliding member having a laminated structure, it is preferable that the same material as the matrix of the surface layer (a composite material layer) (1) is applied to the base member (2). In a laminated structure of different materials, a local battery is easily formed between materials in a corrosive environment, and corrosion damage by the local battery is promoted. This phenomenon is more remarkable as the difference in pitting potential between the materials is larger. If the same type of material is applied to the base member and the surface layer (composite material layer) in order to suppress and prevent this corrosion phenomenon, the pitting potential difference is reduced, which is advantageous in terms of corrosion resistance.

Applying the same type of material to the matrix of the surface layer (1) and the base member (2) is effective in preventing damage due to residual stress or the like at the lamination interface.
That is, when a corrosion-resistant structural material such as austenitic stainless steel is used as the base member, the difference in thermal expansion coefficient between the surface layer (composite material layer) and the surface layer is large, and a large residual stress remains in the product sliding member. While damage may be induced, when the base member is made of the same material as the matrix, the difference in thermal expansion coefficient is reduced, and the breakage resistance is enhanced.

[0016] Regarding the constituent materials of the matrix and the base member, the "same material" refers to, for example, the above-mentioned Ni-based alloy or Ti-based alloy (matrix forming metal), and applies "Ni-based alloy 1" to the matrix. In this case, a material belonging to the composition range of the “Ni-based alloy 1” described therein may be used as the base material layer, and when the “Ti-based alloy” is used as the matrix, the “Ti-based alloy” described therein may be used. Base alloy ''
Means that those belonging to the composition range described above are used.

Next, the production of the sliding member by HIP processing or overlay welding will be described. The HIP treatment is performed by filling a capsule with a uniform powder mixture of a metal powder serving as a matrix and hard particles serving as a reinforcing material (degassing and sealing), and holding the mixture under pressure and heat for an appropriate time. Preferably, the treatment temperature is about 900-1300 ° C., and the pressure is about 7
It is set appropriately within the range of 0 to 150 MPa. The processing time is about 1 to 10 hours. After the treatment, the capsule is removed by machining to obtain a sliding member. When the sliding member is manufactured as a laminated structure (FIG. 1), the powder mixture (surface layer forming material) and the base member may be laminated and filled in a capsule and HIP processing may be performed. The interface between the formed surface layer (sintered body) and the base member is strongly bonded and integrated as an effect of diffusion bonding generated by the HIP process.

In the case of manufacturing a sliding member having a weld overlay as a surface layer, a powder plasma welding overlay method or the like is applied, and a powder mixture (metal powder serving as a matrix and hard particles serving as a reinforcing material) is formed. While supplying the mixture to the surface of the base member, the metal powder is melted by plasma arc heat, a molten pool containing hard particles is generated and solidified to form a surface layer.

In the overlay welding, the surface layer of the base member is melted by plasma arc heat. This is necessary in order to form a strong metallurgical bond between the base member and the surface layer, but the material of the base member is different from the matrix of the surface layer (composite material layer) (for example, austenitic stainless steel). Steel, etc.), dilute the surface layer matrix,
This is a factor that impairs the performance of the surface layer (such as salt water resistance). When the same type of material is applied to the matrix and the base member as described above, an effect of suppressing and preventing such a problem can also be obtained.

FIGS. 2 and 3 show examples of sliding members having a laminated structure. FIG. 2 shows a state in which the hollow cylindrical sliding member (hereinafter, referred to as “multilayer sleeve”) (3) of FIG. 3 is fitted to a predetermined portion (a portion facing the bearing 6) of the shaft body (5), This is an example in which a sliding member is configured. The surface layer (which is a composite material layer) of the multilayer sleeve (3) (1) is a stationary sliding member (bearing)
It becomes a sliding surface for (6). FIG. 3 shows that a concave portion (g) surrounding the shaft surface is provided at a predetermined portion (a portion facing the bearing 6) of the shaft body (5), and the concave layer (g) has a surface layer (1) made of a composite material. This is an example in which a rotation side sliding member is formed by forming a rotation member. The surface layer (1) in the concave groove (g) can be formed as a sintered body layer or a build-up welding layer. The layer thickness of the surface layer (1) is, for example, 1 to 5 mm.

The filling of the powder mixture (mixture of matrix metal powder and hard particles) in the concave groove (g) required when the surface layer (1) of the concave groove (g) is formed by HIP processing is performed by a shaft body. What is necessary is just to use the capsule of suitable shape which encloses the peripheral surface of (5). After HIP, the capsule is removed (machined) to obtain a sliding member having a surface layer (composite material layer as a sintered body). When the surface layer (1) in the concave groove (g) is formed by overlay welding, the shaft (5) is installed horizontally on a rotating device, and the plasma arc is supplied while the powder mixture is supplied into the concave groove (g). The bead forming operation for melting by heat may be performed along the circumferential direction while rotating the shaft. After welding, the bead surface is subjected to finish machining to obtain a sliding member having a surface layer (composite material overlay).

In the above description, the shaft body (5) is described as a rotating body. However, when the shaft body (5) is a sliding member that reciprocates in the axial direction, it corresponds to the reciprocating stroke. A surface layer (1) made of a composite material is formed over the region of the axial length. The composite material of the present invention forms a surface layer of a driving-side sliding member such as a rotating shaft and a stationary-side sliding member that supports the shaft. The surface layer serving as the sliding surface of the fixed-side sliding member is also formed by applying the above-described HIP processing, overlay welding, or the like.

[0023]

EXAMPLES [Preparation of Test Material] A powder mixture of a metal powder (a matrix forming raw material) and hard particles was used as a sintering raw material.
A test material is obtained by performing IP processing. Tables 1 and 2 show the constitution and various physical properties of the test material.

(1) Material type (composition weight%) and physical properties (pitting potential, hardness) of matrix metal Ni-based alloy Cr: 15.5, Mo: 16.0, W: 3.56, Fe: 6.3, N
i: Bal Pitting corrosion potential: 739 mV Hardness (HRC): 15

Ni-base alloy Cr: 20.9, Mo: 9.1, Nb: 3.4, Ta: 0.3, Fe: 2.7, Ni: Bal Pitting potential: 745 mV Hardness (HRC): 17

Ni-base alloy Cr: 36.2, Mo: 15.4, Ni: Bal Pitting corrosion potential: 695 mV Hardness (HRC): 42

Ti-based alloy Al: 6.1, V: 4.2, Ti: Bal. Pitting potential: 1200 mV Hardness (HRC): 13

(2) Grade and particle size of hard particles (average particle size in parentheses) TiC: 75 to 150 μm ZrC: 2 to 4 μm (3.1 μm) HfC: 1-2 μm (1.5 μm) VC: 75 to 150 μm NbC: 75 to 150 μm TaC: 75 to 1570 μm CR ₃ C ₂ : _{2 to 4} μm (3.2 μm) Mo ₂ C: _{2 to} 4 μm (2.9 μm) W ₂ C: 100 to 200 μm

TiB ₂ : 1-2 μm (1.5 μm) TiN: 1.2-1.8 μm (1.4 μm) TiSi ₂ : 6-12 μm (7.2 μm)

(3) Hot Isostatic Pressing (HIP) Treatment The metal powder and the hard particles are uniformly mixed by a ball mill, filled in a capsule (mild steel container) (degassed and sealed), and HIPed (1100 ° C.) × 10 MPa × 2 Hr). HIP
After that, the capsule is removed (machined) and the test material (sintered body)
Take out.

[Physical properties of test materials] (1) Measurement of pitting potential (Vc'100) (according to JIS G0577) Test solution: artificial seawater (3.5% NaCl solution), liquid temperature 25 ° C, sweep rate 20
mV / min, Ar degassing. Test piece: φ14.8 × 2t

(2) Abrasion test a Evaluation of abrasion resistance using an Ohgoshi quick wear tester. The flat test piece is pressed against a counterpart material (rotary disk), and the wear amount (mm ² / N) is calculated from the depth and width of the wear mark formed on the test piece surface. Counterpart material: silicon nitride ceramics Test distance: 400 m Peripheral speed: 3.38 m / sec Load: 61 N

(3) Wear test b (slurry wear test) Evaluation of resistance to earth and sand wear erosion. A cylindrical test material is coaxially mounted on a shaft (connected to a rotary drive), and a mating material (bearing) is arranged to rotate in the slurry. After a lapse of a predetermined time, the change amounts of the outer diameter of the test material and the inner diameter of the mating material (bearing) are measured, and the total value of the change amounts is calculated as the wear amount. Mating material (bearing): Silicon nitride ceramics Sliding diameter: φ30 mm Peripheral speed: 5.7 m / sec Slurry suspended particles: No. 8 silica sand Slurry concentration: 5000 ppm Test time: 100 hr

(4) Measurement of bending strength Test method: three-point bending test (JIS B1601) Test piece: 3 × 4 × 40, mm Span distance: 30 mm Test temperature: room temperature

[0035]

[Table 1]

In the table, Comparative Examples Nos. 101 to 104 are examples of a metal single-phase material containing no hard particles (the metal material type is the same as the matrix metal of the invention), and No. 105 and No. 106 are matrix metals. And hard particles, which are examples of insufficient or excessive hard particle content.

Comparative Examples Nos. 101 to 104 have high pitting potential and bending strength, but are inferior in wear resistance. On the other hand,
The invention examples have high pitting corrosion potential and sufficient bending strength, and also have outstanding wear resistance (sliding wear resistance to ceramics and earth and sand wear resistance to slurries). The pitting potential of WC-12Co cemented carbide (a pitting potential of less than 200 mV), which is a representative material for wear resistance, as well as the pitting potential of austenitic stainless steel 316L (a typical material) Comparative Examples No. 105 and No. 106, which greatly exceed about 370 mV), are composite materials similar to the invention examples, but the former has a poor effect of improving abrasion resistance due to lack of hard particles, and the latter has hard particles. Is excessively contained, it is brittle, has a remarkably insufficient bending strength, and lacks suitability as a structural material.

[0038]

The composite material for sliding members of the present invention has outstanding resistance to severe sliding wear, earth and sand abrasion erosion (slurry abrasion), and the like. Has higher salt water resistance and acid corrosion resistance than stainless steel. Accordingly, high wear resistance and high corrosion resistance are required, for example, a sliding member exposed to seawater containing earth and sand particles such as silica sand, for example, a sliding member constituting a bearing portion of a blade shaft of a drainage pump. Various industrial equipment
It is suitable for the sliding portion of the device, and brings effects such as improvement of durability and reduction of maintenance.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing an embodiment of a sliding member of the present invention.

FIG. 2 is a partially cutaway front view showing an embodiment of the sliding member of the present invention.

FIG. 3 is a partially cutaway front view showing an embodiment of the sliding member of the present invention.

[Explanation of symbols]

 1: Surface layer 2: Base member 3: Sliding member 5: Shaft 6: Bearing

Claims (10)

[Claims] 1. A composite comprising a matrix and hard particles occupying 40 to 80% by weight, wherein the matrix is formed of a metal having a pitting potential of 400 mV or more, and the pitting potential of the composite is 400 mV or more. -Composite material for sliding members with excellent wear resistance. 2. Hard particles are Ti, Zr, Hf, V, N
The composite material for a sliding member according to claim 1, wherein the composite material is one or two or more kinds of particles selected from carbide, boride, nitride, silicide, and oxide of b, Ta, Cr, Mo, or W. 3. The composite material for a sliding member according to claim 1, wherein the matrix is made of a Ni-based alloy. 4. The composite material for a sliding member according to claim 1, wherein the matrix is made of a Ti-based alloy. 5. The sintered body according to claim 1, wherein the sintered body is formed by subjecting a powder mixture of a metal powder and a hard particle serving as a matrix to hot isostatic pressing. Composite material for sliding members. 6. A sliding member excellent in corrosion resistance and abrasion resistance having a surface layer made of the composite material according to claim 1 in a region to be a sliding surface. 7. A base member and a surface layer made of a composite material laminated on a side to be a sliding surface of the base member.
3. The sliding member according to claim 1. 8. The sliding member according to claim 7, wherein the base member and the matrix of the composite material forming the surface layer are made of the same material. 9. The sliding member according to claim 7, wherein the sliding member is a multi-layer sleeve in which a surface layer made of a composite material is laminated on a side of a base member having a hollow cylindrical shape to be a sliding surface. Element. 10. The sliding member according to claim 6, which is mounted on a shaft that rotates or reciprocates or a member that supports the shaft.