阅读说明：本技术 滑动部件 (Sliding component ) 是由 伊泽佳典 马渕豊 伊东昭信 荒井淳一 最上操 原田正直 野上盛之 于 2018-07-19 设计创作，主要内容包括：本发明提供一种滑动部件。本发明的滑动部件在基材上具有覆膜。而且,上述覆膜含有硬质金属材料粒子、以及硬度比该硬质金属材料粒子低的耐腐蚀性金属材料粒子,上述硬质金属材料粒子至少含有维氏硬度为600Hv以上的粒子,上述耐腐蚀性金属材料粒子由从铜(Cu)、钴(Co)、铬(Cr)以及镍(Ni)所形成的群中选择的至少一种金属、或含有该金属的合金形成,在上述覆膜的剖面,上述硬质金属材料粒子以岛状分散在上述耐腐蚀性金属材料粒子的粒子块中,上述耐腐蚀性金属材料粒子的面积率为30％以上,所以能够防止覆膜内部的硬质金属材料粒子的腐蚀,长期地维持耐磨损性。(The invention provides a sliding member. The sliding member of the present invention has a coating film on a base material. The coating contains hard metal material particles containing at least particles having a Vickers hardness of 600Hv or more, and corrosion-resistant metal material particles having a hardness lower than that of the hard metal material particles, the corrosion-resistant metal material particles being formed of at least one metal selected from the group consisting of copper (Cu), cobalt (Co), chromium (Cr), and nickel (Ni), or an alloy containing the metal, and the hard metal material particles being dispersed in island-like shapes in a sub-block of the corrosion-resistant metal material particles in a cross section of the coating, and the area ratio of the corrosion-resistant metal material particles being 30% or more, so that corrosion of the hard metal material particles inside the coating can be prevented, and the wear resistance can be maintained for a long period of time.)

1. A sliding member having a coating film on a base material, characterized in that,

the coating film contains: hard metal material particles and corrosion-resistant metal material particles having a hardness lower than that of the hard metal material particles,

the hard metal material particles at least contain particles having a Vickers hardness of 600Hv or more,

the corrosion-resistant metal material particles are formed of at least one metal selected from the group consisting of copper (Cu), cobalt (Co), chromium (Cr) and nickel (Ni), or an alloy containing the metal,

the hard metal material particles are dispersed in island-like shapes in the particle block of the corrosion-resistant metal material particles in a cross section of the coating, and an area ratio of the corrosion-resistant metal material particles is 30% or more.

2. Sliding part according to claim 1,

the hard metal material particles are formed of at least one metal selected from the group consisting of cobalt (Co), chromium (Cr) and nickel (Ni), or an alloy containing the metal,

the hard metal material particles have a Vickers hardness of 700Hv or more.

3. Sliding part according to claim 1 or 2,

the area ratio of the corrosion-resistant metal material particles is 50% or more.

4. Sliding component according to one of claims 1 to 3,

the area ratio of the corrosion-resistant metal material particles is 80% or more.

5. The sliding member according to any one of claims 1 to 4,

the hard metal material particles have an area ratio of 5% to 50%.

6. The sliding member according to any one of claims 1 to 5,

the particles of the corrosion-resistant metal material have an amorphous state at least in part of the interfaces between the particles of the corrosion-resistant metal material and the particles of the hard metal material.

7. The sliding member according to any one of claims 1 to 6,

the porosity is 10 area% or less.

8. The sliding member according to any one of claims 1 to 7,

the porosity is 5 area% or less.

9. The sliding member according to any one of claims 1 to 8,

the empty holes are independent holes.

10. The sliding member according to any one of claims 1 to 9,

the natural potential of the film is more than-600 mV.

11. The sliding member according to any one of claims 1 to 10,

the natural potential of the film is 0mV or more.

12. The sliding member according to any one of claims 1 to 11,

the relative difference between the natural potentials of the film and the substrate is 1100mV or less.

13. The sliding member according to any one of claims 1 to 12,

the base material is aluminum alloy.

Technical Field

The present invention relates to a sliding member, and more particularly, to a sliding member containing hard metal material particles and having improved wear resistance.

Background

Sliding parts used in internal combustion engines of automobiles and the like are required to have good wear resistance and small aggressiveness (attack to dust).

Japanese patent laying-open No. 6-179937 of patent document 1 discloses a sintered alloy for a valve seat, in which hard alloy particles, a solid lubricant, and ceramic particles are dispersed in a martensite structure of an iron-based alloy, thereby improving wear resistance and reducing aggressiveness.

Documents of the prior art

Patent document

Patent document 1: japanese unexamined patent publication No. 6-179937

Disclosure of Invention

Technical problem to be solved by the invention

However, in general, a fired alloy has a large number of pores between alloy particles of a material, and when corrosion occurs in the pores inside a sliding member, the new surface is not renewed because the pores are different from the sliding surface, so that the corrosion progresses until the vicinity of grain boundaries where the particles are bonded to each other corrodes, the bonding strength between the particles decreases, and the wear resistance decreases.

In recent years, the proportion of intermittent operation has increased due to a demand for fuel saving, and condensed water obtained by condensing moisture contained in exhaust gas or the like tends to remain in the pores, and the condensed water reacts with nitrogen oxides and sulfur oxides contained in the exhaust gas to generate acids in the pores.

Further, since pores formed between alloy particles of the fired alloy are narrow, an oxygen concentration cell is formed inside the coating film, and the pores become a starting point of corrosion, and corrosion progresses inside the coating film, thereby lowering the wear resistance.

Therefore, sliding parts used in internal combustion engines are required to have improved corrosion resistance as well as wear resistance and aggressiveness.

The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a sliding member which has high corrosion resistance and can prevent wear resistance from decreasing with time.

Technical solution for solving technical problem

The present inventors have intensively studied to achieve the above object, and as a result, have found that the above object can be achieved by covering most of hard metal material particles with corrosion-resistant metal material particles, and have completed the present invention.

That is, the sliding member of the present invention has a coating film on a base material, and is characterized in that,

the coating film contains hard metal material particles and corrosion-resistant metal material particles having a hardness lower than that of the hard metal material particles,

the hard metal material particles contain at least particles having a Vickers hardness of 600Hv or more,

the corrosion-resistant metal material particles are formed of at least one metal selected from the group consisting of copper (Cu), cobalt (Co), chromium (Cr) and nickel (Ni), or an alloy containing the metal,

in the cross section of the coating, the hard metal material particles are dispersed in island-like shapes in the particle block of the corrosion-resistant metal material particles, and the area ratio of the corrosion-resistant metal material particles is 30% or more.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, since the hard metal material particles are dispersed in island-like particles in the particle block of the corrosion-resistant metal material particles, the hard metal material particles inside the coating film can be prevented from corroding, and the wear resistance can be maintained for a long period of time.

Drawings

Fig. 1 is a schematic cross-sectional view showing an example of a cross section of a sliding member according to the present invention.

Fig. 2 is an enlarged schematic cross-sectional view showing an example of the coated tissue.

Fig. 3 is a cross-sectional SEM image of the sliding member of the second embodiment.

Detailed Description

< sliding part >

The sliding member of the present invention will be described in detail.

As shown in fig. 1, the sliding member 1 has a coating 2 containing hard metal material particles 22 and corrosion-resistant metal material particles 21 having a hardness lower than that of the hard metal material particles 22 on a base material 3, and the hard metal material particles 22 are dispersed in island-like shapes in a particle block of the corrosion-resistant metal material particles 21 in a cross section of the coating 2.

In the present invention, the particle agglomerate means an aggregate of particles in which the surfaces of the particles forming the coating are locally melted and solidified, and the particles of the entire coating are integrally bonded to each other to form an interface, and does not mean an aggregate in which the particles are integrally entangled with each other, or an aggregate in which the particles are integrally entangled by completely melting or dissolving and solidifying the particles.

The corrosion-resistant metal material particles are made of a metal material having better corrosion resistance than iron, and are made of at least one metal selected from the group consisting of copper (Cu), cobalt (Co), chromium (Cr), and nickel (Ni), or an alloy containing the metal.

Chromium is a metal having a higher ionization tendency than iron, but is formed as non-dynamic Cr on the surface₂O₃Oxide film of (2) so thatNot only an alloy containing chromium like stainless steel, but also the corrosion resistance of the metal element is good.

As the alloy, for example, an alloy containing 50 mass% or more of copper is preferably used because of its high natural potential and good corrosion resistance, and examples thereof include a Cu-Ni-Si alloy, a Cu-Co-Si alloy, a Cu-Ag alloy, a Cu-Al alloy, a Cu-Ni alloy, and a Cu-Ti alloy.

In particular, Si-containing alloys such as Cu-Ni-Si alloys and Cu-Co-Si alloys form SiO by Si diffusion on the surface₂The oxide film of (2) which behaves like a non-dynamic film, improves corrosion resistance, and thus can be preferably used.

The cross section of the coating has a sea-island structure in which hard metal material particles are dispersed in island-like shapes in the particle block of the corrosion-resistant metal material particle, and most of the hard metal material particles are covered with the corrosion-resistant metal material particles and are not exposed to the inner surface of the pores in the coating, so that corrosion can be prevented from occurring in the coating.

In addition, soft metal materials generally have a low melting point and are easily melted to be firmly bonded. Since the corrosion-resistant metal material particles have a lower hardness than those of hard metal material particles described later and have a vickers hardness of less than 600Hv, the corrosion-resistant metal material particles are strongly bonded to each other when the particle mass is formed, and the strength and wear resistance of the coating film are improved.

Although the lower limit of the vickers hardness of the corrosion-resistant metal material particles is not particularly limited, the wear resistance is improved by setting the vickers hardness to 80Hv or more.

The area ratio of the corrosion-resistant metal material particles in the cross section of the coating film is 30% or more, preferably 50% or more, and more preferably 80% or more. By increasing the area ratio of the corrosion-resistant metal material particles, the hard metal material particles are covered to improve corrosion resistance, and the corrosion-resistant metal material particles are strongly bonded to each other to improve the film strength.

The hard metal material particles are particles having a hardness higher than that of the corrosion-resistant metal material particles, and may be used as long as they contain particles having a vickers hardness of 600Hv or more, but since they come into contact with the corrosion-resistant metal material particles in the coating film to form local batteries between the corrosion-resistant metal material particles, it is preferable to contain the same kind of metal material as the corrosion-resistant metal material particles.

Specifically, at least one metal selected from the group consisting of cobalt (Co), chromium (Cr), and nickel (Ni), or an alloy containing the metal may be used.

Examples of the alloy include hard cobalt-based alloys such as TRIBALOY (registered trademark) T-400 and Stellite (registered trademark) 6, and hard nickel-based alloys such as TRIBALOY (registered trademark) T-700 and Ni700 (registered trademark) (Ni-32Mo-16Cr-3.1 Si).

The vickers hardness of the hard metal material particles is preferably 700Hv to 1500 Hv. By setting the vickers hardness of the hard metal material particles within the above range, both wear resistance and aggressiveness can be achieved.

The area ratio of the hard metal material particles in the cross section of the coating is preferably 5% or more and 50% or less, more preferably 5% or more and 30% or less, and still more preferably 10% or more and 15% or less.

When the area ratio of the hard metal material particles is within the above range, the hard metal material particles interact with the corrosion-resistant metal material particles to improve the wear resistance and the film strength.

As shown in fig. 2, the coating preferably has an amorphous state 23 at least in part of the interface between the corrosion-resistant metal material particles 21 and the hard metal material particles 22.

Amorphous is a random structure having no regular arrangement of atoms like crystals, is free from inclusions and segregation, is homogeneous and isotropic, and has no lattice defects such as grain boundaries and migration which are starting points of corrosion, and therefore, generally has good corrosion resistance.

By having an amorphous state at the interface between the particles forming the coating, that is, at the surface of the particles, the corrosion resistance of the particles themselves is improved, and even when pores are present between the particles, the generation of corrosion from the inside of the coating can be suppressed.

The amorphous state can be formed by forming a film by a cold spray method described later.

The average particle diameter of crystal grains in the particles is preferably 10 μm or less, and more preferably 5 μm or less. By making the crystal grains in the particles fine, the film strength is improved.

The amorphous state at the particle interface and the crystal grains in the particles can be confirmed by projecting a diffraction pattern onto a detector surface by electron beam backscatter diffraction (EBSD) using a Scanning Electron Microscope (SEM), and analyzing the crystal orientation based on the projected pattern.

The film preferably has a porosity of 10 area% or less, more preferably 5 area% or less, in a cross section. By making the pores small and dense, condensed water is less likely to be retained in the coating film, and crevice corrosion is less likely to occur, so that a decrease in wear resistance can be suppressed for a long period of time.

Although the above-described coating is preferably small in number of pores, in the case where pores inevitably occur, such as in the case where the coating is a fired body, the pores are preferably independent pores. By making the pores independent, condensed water does not intrude into the pores inside the coating film, and an oxygen concentration cell is not formed inside the coating film, and the occurrence of crevice corrosion can be suppressed.

The area ratio of the corrosion-resistant metal material particles, the area ratio of the hard metal material particles, and the porosity in the cross section of the coating film can be calculated by binarizing a scanning electron microscope image (SEM image) by image processing and analyzing the image.

The average particle diameter (diameter corresponding to a circle: diameter of a circle having the same area as the projected area of the particle image) of the corrosion-resistant metal material particles and the hard metal material particles in the cross section of the coating film is preferably 5 to 100 μm, and more preferably 5 to 40 μm.

A dense coating can be formed by making the average particle size of the particles small, but when the particle size is too small, kinetic energy of the particles is reduced in a cold spray method described later, the particles are less likely to be plastically deformed, and close contact between the particles is reduced, possibly resulting in a reduction in coating strength.

The natural potential of the coating is preferably-600 mV or more, and more preferably 0mV or more. By increasing the natural potential of the coating, corrosion hardly progresses, and a decrease in wear resistance can be suppressed for a long period of time.

The thickness of the coating film depends on the temperature of the position where the sliding member is used and the sliding environment, but is preferably 0.05 to 5.0mm, and more preferably 0.1 to 2.0mm, for example.

If the thickness is less than 0.05mm, the strength of the coating film itself is insufficient, and when the strength of the base material is low, plastic deformation may occur. When the thickness exceeds 10mm, the coating may be easily peeled off due to the relationship between the residual stress generated during film formation and the interface intimate contact force.

The relative difference in natural potential between the coating and the base material is preferably 1100mV or less. By reducing the natural potential difference between the coating and the substrate, contact corrosion between different metals can be prevented.

The base material is not particularly limited, and a conventionally used metal can be used as a sliding member of an internal combustion engine, but an aluminum alloy is preferably used because of its high thermal conductivity.

Examples of the aluminum alloy include AC2A, AC8A, ADC12, and the like, which are defined by japanese industrial standards.

The sliding member is excellent in corrosion resistance and wear resistance, and is suitably used in, for example, pistons, piston rings, piston pins, cylinders, crankshafts, camshafts, and valve lifters.

< method for manufacturing sliding Member

The sliding member can be produced by a method of forming a coating by spraying a mixed particle of corrosion-resistant metal material particles and hard metal material particles onto the surface of a base material by cold spraying, a method of pressing a fired body obtained by firing a molded body in which the mixed particle is solidified into a base material, or the like.

Cold spraying is a method of forming a coating by allowing an inert gas to collide with a base material in a solid phase state at a supersonic flow without melting or vaporizing metal particles of a material, and can minimize changes in characteristics of the metal particles and oxidation in the coating due to heat, unlike a method of forming a coating by melting metal particles such as a spray method.

With the cold spray, when the metal particles in a solid phase collide with the base material, the metal particles themselves are plastically deformed, and a part of kinetic energy is converted into thermal energy, and the surfaces of the metal particles are locally melted and solidified, whereby the metal particles are bonded to each other to form a coating film.

At this time, since the temperature of the base material and the metal particles is not higher than the melting point of the metal particles, the surfaces of the locally melted metal particles are rapidly cooled to form an amorphous state at the interface between the particles, and the metal particles are plastically deformed to miniaturize crystal grains in the metal particles.

In the present invention, since the mixed particles of the corrosion-resistant metal material particles and the hard metal material particles are sprayed, the relatively soft corrosion-resistant metal material particles are plastically deformed, stacked and bonded without a gap, and formed into the particle block having the amorphous corrosion-resistant metal material particles at the interface between the particles. Further, since the hard metal material particles are embedded in the particle block, a coating film in which the hard metal material particles are dispersed in island shapes in the particle block is formed.

The speed of spraying the mixed particles is preferably 300 to 1200m/s, more preferably 500 to 1000 m/s.

The pressure of the working gas for spraying the mixed particles is preferably 2 to 5MPa, more preferably 3.5 to 5 MPa. When the pressure of the working gas is less than 2MPa, the particle velocity cannot be obtained and the porosity may increase.

The temperature of the working gas depends on the mixed particles, but is preferably 400 to 800 ℃, and more preferably 600 to 800 ℃.

When the temperature of the working gas is less than 400 ℃, the corrosion-resistant metal material particles are less likely to be plastically deformed, the porosity increases, and the corrosion resistance may be reduced. When the temperature of the working gas exceeds 800 ℃, the corrosion-resistant metal material particles colliding with the base material become too soft, the residual stress decreases, and the coating film may be easily peeled off.

As described above, the working gas may be, for example, nitrogen gas, helium gas or the like, and these gases may be used alone or in combination.

In addition, the firing is a method of firing and solidifying the molded body in which the metal particles are solidified at a temperature lower than the temperature at which the metal particles are melted, and since it is not necessary to melt and bond the metal particles, the change in the characteristics of the metal particles due to heat can be reduced. Therefore, by subjecting the metal particles to strengthening (strengthening), the crystal grains in the metal particles are made fine, whereby the crystal grains in the metal particles can be made fine, and a high-strength coating can be formed.

The molded article obtained by solidifying the metal particles can be formed by a compression molding method in which the metal particles are placed in a mold, or a so-called metal powder injection molding method in which pellets obtained by kneading the metal particles and a binder are molded by the same method as in injection molding of plastic and the binder is removed by heating or the like.

The temperature for firing the molded article depends on the kind of the mixed particles, but is preferably 900 to 1100 ℃.

Examples

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples.

[ first embodiment ]

An aluminum base material (japanese industrial standard H4040 a5056) was prepared by performing groove formation, assuming that the target film thickness was 0.2mm in a state where the seating portion of the engine valve of the cylinder head was machined, and was manufactured.

After injection molding, MIM raw material pellets containing the following mixed particles and a binder were heated, and the degreased body of phi 40 × L14mm was heated at 1000 ℃ for one hour to obtain a fired body.

Corrosion-resistant metal material particles: CaF₂Addition of strengthening processing Cu-2.9Ni-0.7Si alloy particles (average particle diameter 10 μm)

Hard metal material particles: co alloy particles for strengthening processing ((Tribaloy T-400 manufactured by Kennamantal, USA: average particle diameter 45 μm))

Corrosion-resistant metal material particles/hard metal material particles (volume ratio): 89/10

The fired body was cut into a valve seat shape, pressed into a groove of the aluminum base material, and finished into the shape of the seat portion of the engine valve by machining, to obtain a sliding member having a coating film thickness of 0.5 mm.

[ second embodiment ]

The aluminum substrate was rotated and the following mixed particles were cold-sprayed under the following conditions to form a film having a thickness of 1 mm.

Corrosion-resistant metal material particles: cu-2.9Ni-0.7Si alloy particles (average particle diameter 30 μm)

Hard metal material particles: co alloy particles ((Tribaloy T-400 manufactured by Kennamantal, USA): average particle diameter 45 μm)

Corrosion-resistant metal material particles/hard metal material particles (volume ratio): 89/10

High pressure type cold spraying device: kinetiks4000 from CGT

Working gas: nitrogen gas

Gas temperature: 600 deg.C

Gas pressure: 4MPa

Particle velocity: 680 to 720m/s

The aluminum base material on which the coating was formed was finished into the shape of the seat portion of the engine valve of the cylinder head by machining, to obtain a sliding member having a coating thickness of 0.5 mm.

[ third embodiment ]

A sliding member was obtained in the same manner as in the second example, except that the aluminum base material was rotated and the following mixed particles were cold sprayed under the following conditions.

Corrosion-resistant metal material particles: cu-2.9Ni-0.7Si alloy particles (average particle diameter 30 μm)

Hard metal material particles: fe alloy particle (SKH 51: average particle diameter 45 μm)

Corrosion-resistant metal material particles/hard metal material particles (volume ratio): 80/18

High pressure type cold spraying device: kinetiks4000 from CGT

Working gas: nitrogen gas

Gas temperature: 600 deg.C

Gas pressure: 3.5MPa

Particle velocity: 650 to 690m/s

[ fourth embodiment ]

A sliding member was obtained in the same manner as in the second example, except that the aluminum base material was rotated and the following mixed particles were cold sprayed under the following conditions.

Corrosion-resistant metal material particles: SUS440C particle (average particle diameter 30 μm)

Hard metal material particles: co alloy particles ((Tribaloy T-400 manufactured by Kennamantal, USA): average particle diameter 45 μm)

Corrosion-resistant metal material particles/hard metal material particles (volume ratio): 81/18

High pressure type cold spraying device: kinetiks4000 from CGT

Working gas: nitrogen gas

Gas temperature: 750 ℃ C

Gas pressure: 4MPa

Particle velocity: 740 to 780m/s

[ fifth embodiment ]

The following mixed particles were placed in a mold of phi 40, molded at 1000kN, and the compression-molded article of phi 40 XL 14mm was heated at 1000 ℃ for one hour to obtain a fired article.

Corrosion-resistant metal material particles: CaF₂Cu-2.9Ni-0.7Si alloy particles (average particle size 80 μm) were added

Hard metal material particles: ni alloy particles ((Tribaloy T-700, manufactured by Kennamantal, USA): average particle diameter 45 μm)

Corrosion-resistant metal material particles/hard metal material particles (volume ratio): 82/14

The fired body was cut into a valve seat shape, pressed into a groove of the aluminum base material, and finished into the shape of the seat portion of the engine valve by machining, to obtain a sliding member having a coating film thickness of 0.5 mm.

[ sixth embodiment ]

A sliding member was obtained in the same manner as in the fifth example, except that the following mixed particles were used.

Corrosion-resistant metal material particles: CaF₂Cu-2.9Ni-0.7Si alloy particles (average particle size 80 μm) were added

Hard metal material particles: co alloy particles ((Tribaloy T-400 manufactured by Kennamantal, USA): average particle diameter 45 μm)

Corrosion-resistant metal material particles/hard metal material particles (volume ratio): 57/42

[ seventh embodiment ]

A sliding member was obtained in the same manner as in the fifth example, except that the following mixed particles were used.

Corrosion-resistant metal material particles: CaF₂Cu-2.9Ni-0.7Si alloy particles (average particle size 80 μm) were added

Hard metal material particles: co alloy particles ((Tribaloy T-400 manufactured by Kennamantal, USA): average particle diameter 45 μm, Vickers hardness 905Hv)

Hard metal material particles: fe alloy particle (SKH 51: average particle diameter 45 μm)

Corrosion-resistant metal material particles/Co alloy particles/Fe alloy particles (volume ratio): 46/17/28

[ eighth embodiment ]

A sliding member was obtained in the same manner as in the fifth example, except that the following mixed particles were used.

Corrosion-resistant metal material particles: CaF₂Cu-2.9Ni-0.7Si alloy particles (average particle size 80 μm) were added

Hard metal material particles: fe alloy particle (SKH 51: average particle diameter 45 μm)

Corrosion-resistant metal material particles/hard metal material particles (volume ratio): 39/51

[ first comparative example ]

1% by mass of zinc stearate was added to the following mixed particles, followed by mixing, placing the mixture in a mold of phi 40, and molding the mixture at 1000kN to obtain a compressed molded article of phi 40 XL 14 mm.

Corrosion-resistant metal material particles: cu alloy particles (average particle size 80 μm)

Hard metal material particles: co alloy particles ((Tribaloy T-400 manufactured by Kennamantal, USA): average particle diameter 45 μm)

Hard metal material particles: fe + graphite diffusion Fe alloy particles (average particle diameter 45 μm)

Corrosion-resistant metal material particles/Co alloy particles/Fe alloy particles (volume ratio): 15/36/38

A sliding member was obtained in the same manner as in the fifth example except that copper for infiltration was disposed on the upper portion of the compression molded body and a fired body heated at 1000 ℃ for one hour was used in an atmosphere of ammonia decomposition gas.

[ second comparative example ]

A sliding member was obtained in the same manner as in the fifth example, except that the following mixed particles were used.

Corrosion-resistant metal material particles: CaF₂Cu-2.9Ni-0.7Si alloy particles (average particle size 80 μm) were added

Hard metal material particles: fe + graphite diffusion Fe alloy particles (average particle diameter 45 μm)

Corrosion-resistant metal material particles/hard metal material particles (volume ratio): 48/42

[ third comparative example ]

A sliding member was obtained in the same manner as in the fifth example, except that the following mixed particles were used.

Corrosion-resistant metal material particles: cu alloy particles (average particle size 80 μm)

Hard metal material particles: co alloy particles ((Tribaloy T-400 manufactured by Kennamantal, USA): average particle diameter 45 μm)

Hard metal material particles: fe + graphite diffusion Fe alloy particles (average particle diameter 45 μm)

Corrosion-resistant metal material particles/Co alloy particles/Fe alloy particles (volume ratio): 10/27/53

[ fourth comparative example ]

A sliding member was obtained in the same manner as in the fifth example, except that the following mixed particles were used.

Hard metal material particles: co alloy particles ((Tribaloy T-400 manufactured by Kennamantal, USA): average particle diameter 45 μm)

Hard metal material particles: fe + graphite diffusion Fe alloy particles (average particle diameter 45 μm)

Co alloy particles/Fe alloy particles (volume ratio): 36/55

[ fifth comparative example ]

A sliding member was obtained in the same manner as in fifth example 5 except that the following mixed particles were used.

Hard metal material particles: co alloy particles ((Tribaloy T-400 manufactured by Kennamantal, USA): average particle diameter 45 μm)

Hard metal material particles: fe + graphite diffusion Fe alloy particles (average particle diameter 45 μm)

Co alloy particles/Fe alloy particles (volume ratio): 22/68

< evaluation >

The sliding members of the first to eighth embodiments and the first to fifth comparative examples were evaluated by the following methods.

Tables 1 and 2 show the evaluation results.

(Observation of coated tissue)

Electron beam backscatter diffraction (EBSD) was performed by a Scanning Electron Microscope (SEM), and the presence or absence of sea-island structures, the presence or absence of amorphism, crystal grain size in the particles, porosity, and corrosion sites in the coating structure were observed. Fig. 3 shows a cross-sectional SEM image of the sliding member according to the second embodiment.

(hardness)

The vickers hardness of the corrosion-resistant metal material particle portion and the hard metal material particle portion in the coating film was measured and calculated in accordance with the vickers hardness test ((japanese industrial standard) JIS Z2244).

(Corrosion resistance)

The steel plate was immersed in 0.5 mass% nitric acid (liquid temperature: 25 ℃) for 20 hours to remove corrosion products, and the weight was measured to calculate the mass loss rate from the mass before and after the corrosion resistance test.

(measurement of Natural potential)

A film having a thickness of 8mm was formed on the surface of an aluminum alloy substrate, and one surface of a sample having a thickness of 5mm and a 15mm square (□) of a portion from which the film was cut was polished with a #1000 water-resistant paper, leaving a 10mm square corner, to prepare a sample electrode, and the natural potential was measured in 0.5 wt% nitric acid (25 ℃ C.) with platinum as a counter electrode.

(abrasion resistance)

The wear amount of the sliding member after the corrosion resistance test was measured under the following conditions using a valve seat wear tester manufactured by hokkiso co.

Specifically, the shape of the seating portion of the engine valve of the cylinder head before and after the test is obtained by the shape measuring device, the wear amounts at four positions are measured, and the average value is calculated and used as the wear amount.

Relative valve material: SUH35

And (3) testing temperature: 300 deg.C

Upper and lower speeds: 3000 times/min

Number of valve rotations: 5rpm

Number of seats: 540000 times

[ Table 1]

[ Table 2]

As is clear from the results in tables 1 and 2, the sliding members of examples in which the hard metal material particles are dispersed in the form of islands in the particle block of the corrosion-resistant metal material particles and the area ratio of the corrosion-resistant metal material particles is 30% or more have better corrosion resistance and better wear resistance over time than the sliding members of comparative examples.

Further, it was confirmed that the sliding members according to the second to fourth examples, which have amorphous interfaces between particles, have better corrosion resistance than the sliding members according to the fifth to eighth examples, and that the amorphous interfaces between particles can prevent corrosion even if condensed water enters the coating.

Further, it is understood that the sliding members according to the second to fourth embodiments can form a coating having high hardness by plastically deforming the corrosion-resistant metal material particles at the time of forming the coating, and by miniaturizing the crystals in the particles.

Description of the reference numerals

1 a sliding member; 2, laminating; 21 corrosion-resistant metallic material particles; 22 hard metal material particles; 23 is amorphous; 3, a base material.