Laminate, sliding member including same, and laminate production method

Abstract

The present disclosure provides a means for improving the abrasion resistance of a film formed on a base material. Provided is a laminate comprising a base material and a film formed on the base material, wherein: the film is obtained by dispersing hard particles in a matrix that contains a Cu alloy; the hard particles contain Fe, Mo, and Si; the hard particles have a soft part, the main component of which is a Fe-containing phase, and a hard part, the main component of which is a Mo compound and which covers at least part of the surface of the soft part; and when the Vickers hardness of the soft part is represented as HV1 [unit: HV] and the Vickers hardness of the hard part is represented as HV2 [unit: HV], the following expression 1 is satisfied: HV1<HV2.

Description

Laminate, sliding member having the same, and method for manufacturing the laminate

[0001] The present invention relates to a laminate, a sliding member having the same, and a method for manufacturing the laminate.

[0002] Valve seats, a component of automobile engines, are sliding members located in the cylinder head, specifically in the annular portion that contacts the valve head. High wear resistance is required for these components. To meet this demand, the development of alloys with superior wear resistance is being actively pursued.

[0003] For example, Japanese Patent Publication No. 4494048 discloses a build-up wear-resistant copper alloy characterized by comprising, by mass%, nickel: 16.5-24.5%, iron: 3.0-20.0%, silicon: 0.5-5.0%, boron: 0.05-0.5%, chromium: 0.3-5.0%, one or more of molybdenum, tungsten, and vanadium: 3.0-20.0%, with the remainder being copper and unavoidable impurities. According to the above document, such a configuration improves build-up properties such as weldability and crack resistance during build-up, and ensures a build-up wear-resistant copper alloy and valve seats for internal combustion engines that also possess excellent wear resistance. Furthermore, the above-mentioned literature states that the wear-resistant copper alloy in question has a Cu-Ni-Si matrix in which hard particles harder than the matrix, Fe-Mo or Co-Mo compounds, and nickel silicide are dispersed, and that the hard particles have a structure in which Fe-Ni-Mo-Si hard phase fine particles are dispersed in a Ni-Fe-Si solid solution.

[0004] However, our investigations have revealed that coatings formed using the alloys described in the above-mentioned literature may have insufficient wear resistance.

[0005] Therefore, the object of the present invention is to provide a means for improving the abrasion resistance of a coating formed on a substrate.

[0006] To solve the above problems, the inventors considered adopting a cold spray method as a technique for forming a film on a substrate in which hard particles are dispersed in a matrix containing a Cu alloy. They found that the above problems could be solved by using particles as hard particles that have a relatively soft portion and a relatively hard portion that covers the surface of the soft portion, and thus completed the present invention.

[0007] In other words, one embodiment of the present invention is a laminate comprising a substrate and a film formed on the substrate, wherein the film is composed of hard particles dispersed in a matrix containing a Cu alloy, the hard particles contain Fe, Mo and Si, and the hard particles have a soft portion mainly composed of an Fe-containing phase and a hard portion mainly composed of a Mo compound that covers at least a part of the surface of the soft portion, and the Vickers hardness of the soft portion is HV １ [Unit: HV], the Vickers hardness of the hardened part is HV ２ When the unit is HV, then Equation 1: HV １ <HV ２ It is a laminate that satisfies the following conditions.

[0008] This is a schematic cross-sectional view showing hard particles constituting the coating of a laminate according to one embodiment of the present invention. This is a perspective view showing the appearance of hard particles constituting the coating of a laminate according to another embodiment of the present invention.

[0009] The embodiments of the present invention will be described below, but the technical scope of the present invention should be determined based on the claims and is not limited to the following forms.

[0010] <Laminate> One embodiment of the present invention is a laminate comprising a substrate and a film formed on the substrate, wherein the film is composed of hard particles dispersed in a matrix containing a Cu alloy, the hard particles contain Fe, Mo and Si, and the hard particles have a soft portion mainly composed of an Fe-containing phase and a hard portion mainly composed of a Mo compound that covers at least a part of the surface of the soft portion, and the Vickers hardness of the soft portion (hereinafter, "Vickers hardness" is also simply referred to as "hardness") is HV １ [Unit: HV], the Vickers hardness of the hardened part is HV ２When the unit is HV, then Equation 1: HV １ <HV ２ This laminate satisfies the following conditions. The laminate according to this embodiment can improve the wear resistance of the coating. Since the laminate according to this embodiment has a coating with excellent wear resistance, it is preferably used in the sliding parts of sliding members, and more preferably in the sliding parts of sliding members of internal combustion engines (for example, automobile engines).

[0011] [Base Material] The material of the base material is not particularly limited, but it is preferably a material used for sliding members. When the sliding member is a sliding member of an internal combustion engine (e.g., an automobile engine), the material of the base material is preferably selected from the group consisting of aluminum, iron, titanium, copper, and their alloys. Examples of aluminum alloys include AC2A, AC8A, and ADC12 as specified in the Japanese Industrial Standards. Examples of iron alloys include SUS304 and iron-based sintered alloys as specified in the Japanese Industrial Standards. Examples of copper alloys include beryllium copper and copper alloy-based sintered alloys. Among these, the material of the base material is preferably aluminum or an aluminum alloy. The shape of the base material is also not particularly limited, and the shape of a member requiring a wear-resistant coating can be appropriately adopted.

[0012] [Coating Film] The coating film is formed by dispersing hard particles in a matrix containing a copper (Cu) alloy. As will be described later, the laminate according to this embodiment is manufactured by colliding mixed particles of hard particles and Cu alloy particles onto a substrate (preferably, the surface of the substrate) by the cold spray method to form a coating film on the substrate. Here, since the Cu alloy is a soft material and easily undergoes plastic deformation, when Cu alloy particles collide with the substrate at high speed by a cold spray device, they adhere to the substrate in a film form due to plastic deformation. On the other hand, since the material constituting the hard particles is hard, it is difficult to undergo plastic deformation. Therefore, when hard particles collide with the substrate at high speed by a cold spray device, the hard particles are buried in the Cu alloy film while maintaining the structure before cold spraying. As a result, a coating film in which hard particles are dispersed in a matrix containing a Cu alloy is formed on the substrate. Whether the coating film has such a form can be determined by observing the cross-section of the coating film with a scanning electron microscope (SEM) and confirming whether it has an island structure in which hard particles are dispersed in the form of islands in the sea composed of the Cu alloy.

[0013] (Cu Alloy) As described above, the Cu alloy constitutes the matrix in the coating film. In this specification, "Cu alloy" refers to an alloy in which the content of Cu is more than 50% by mass (with Cu as the main component). Since the Cu alloy has a high natural potential, a coating film with excellent corrosion resistance can be formed. Examples of the Cu alloy include Cu-Ni-Si alloy, Cu-Co-Si alloy, Cu-Ag alloy, Cu-Al alloy, Cu-Ni alloy, and Cu-Ti alloy. Among them, it is preferable that the Cu alloy contains Si such as Cu-Ni-Si alloy or Cu-Co-Si alloy. The alloy containing Si diffuses Si on the surface to form an oxide film of SiO ２ and the oxide film behaves like a passive film, thereby exhibiting excellent corrosion resistance.

[0014] The Cu alloy is a material softer than the hard particles, and its Vickers hardness is preferably 400 HV or less, more preferably 350 HV or less, and even more preferably 300 HV or less. When the Vickers hardness of the Cu alloy is within such a range, when forming a film by cold spray, the Cu alloy particles can be firmly bonded to each other, and the strength of the film can be improved. The lower limit of the Vickers hardness of the Cu alloy is not particularly limited, but from the viewpoint of the wear resistance of the film, it is preferably 80 HV or more, and more preferably 100 HV or more. The numerical range of the Vickers hardness of the Cu alloy is preferably 80 to 400 HV, more preferably 80 to 350 HV, and even more preferably 100 to 300 HV.

[0015] The area ratio of the Cu alloy in the cross-section of the film is not particularly limited, but is preferably 30% or more, more preferably 50% or more, and even more preferably 80% or more. When the area ratio of the Cu alloy is within the above range, the strength of the film can be improved. The upper limit of the area ratio of the Cu alloy is not particularly limited, but from the viewpoint of the wear resistance of the film, it is preferably 95% or less, and more preferably 90% or less. The preferable numerical range of the area ratio of the Cu alloy is preferably 30 to 95%, more preferably 50 to 95%, and even more preferably 80 to 90%. The area ratio of the Cu alloy can be controlled by adjusting the ratio of the Cu alloy particles to the hard particles when preparing the mixed particles in the method for manufacturing the laminate using the cold spray method described later.

[0016] (Hard Particles) Hard particles contribute to the wear resistance of the coating. Hard particles essentially contain iron (Fe), molybdenum (Mo), and silicon (Si). Hard particles may contain metals other than the above essential components, as long as they have soft and hard parts as described later, but preferably consist only of iron (Fe), molybdenum (Mo), silicon (Si), and unavoidable impurities. In this specification, "unavoidable impurities" means those present in the raw materials or inevitably mixed into the hard particles during the manufacturing process. These unavoidable impurities are essentially unnecessary, but are acceptable because they are present in trace amounts and do not affect the properties of the hard particles. The content of unavoidable impurities is preferably less than 0.5% by mass, more preferably less than 0.1% by mass, and even more preferably less than 0.01% by mass, relative to the total mass of the hard particles.

[0017] The composition of Fe, Mo, and Si in the hard particles is not particularly limited, but from the viewpoint of promoting the formation of the soft part, the Fe content is preferably more than 50% by mass, and more preferably between 50% by mass and 70% by mass. Also from the viewpoint of promoting the formation of the hard part, the Si content is preferably 4% by mass or more, more preferably 4.5% by mass or more, and even more preferably 4.8% by mass or more. Furthermore, when the hard particles consist only of Fe, Mo, Si, and unavoidable impurities, from the viewpoint of further improving the wear resistance of the coating, the composition is preferably Mo: 28-45% by mass, Si: 1-10% by mass, with the remainder being Fe and unavoidable impurities; more preferably Mo: 30-42% by mass, Si: 1.5-8% by mass, with the remainder being Fe and unavoidable impurities; even more preferably Mo: 32-38% by mass, Si: 3-7% by mass, with the remainder being Fe and unavoidable impurities; particularly preferably Mo: 32.5-37% by mass, Si: 4-6% by mass, with the remainder being Fe and unavoidable impurities; and most preferably Mo: 32.5-35.5% by mass, Si: 4-4.8% by mass, with the remainder being Fe and unavoidable impurities. When the composition ratio is within the above range, it becomes easier to form soft and hard parts having a predetermined Vickers hardness. The composition of the hard particles can be confirmed using inductively coupled plasma atomic emission spectroscopy (ICP-AES). In the examples described later, when the hard particles consist only of Fe, Mo, Si, and unavoidable impurities, their composition, which is Mo: A mass%, Si: B mass%, and the remainder being Fe and unavoidable impurities, will be denoted as "Fe-AMo-BSi".

[0018] In the laminate according to this embodiment, the hard particles contained in the film have a soft portion mainly composed of an Fe-containing phase and a hard portion mainly composed of a Mo compound and covering at least a part of the surface of the soft portion. Since the Mo compound is rich in lubricity, it is considered that the presence of this on the surface of the hard particles reduces the friction coefficient of the film and improves the wear resistance. As will be described later, the laminate according to this embodiment is manufactured by colliding mixed particles of hard particles and Cu alloy particles onto a base material (preferably, the surface of the base material) by a cold spray method to form a film on the base material. Since the hard particles are harder than the Cu alloy, in the matrix of the Cu alloy, the hard particles are embedded while maintaining the structure before cold spray. Therefore, the hard particles present in the film and the hard particles as raw materials before cold spray have substantially the same structure.

[0019] Hereinafter, the structure of the hard particles will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing hard particles constituting a film of a laminate according to an embodiment of the present invention. The hard particle 10 shown in FIG. 1 is composed of a soft portion 11 and a hard portion 12 covering all of the surface of the soft portion 11. In other words, the hard particle 10 has a core-shell structure composed of a soft portion 11 as a core and a hard portion 12 as a shell. FIG. 2 is a perspective view showing the appearance of hard particles constituting a film of a laminate according to another embodiment of the present invention. The hard particle 10 shown in FIG. 2 has a configuration in which the surface of the spherical soft portion 11 is partially covered by a plurality of hard portions 12 (a plurality of hard portions 12 are attached to the surface of the spherical soft portion 11).

[0020] The hard particles 10 shown in FIGS. 1 and 2 both have a form in which at least a part of the surface of the soft portion 11 is covered by the hard portion 12. The soft portion is an Fe-containing phase (for example, α-phase (ferrite), γ-phase (austenite), iron silicide (Fe ５ Si ３ 、Fe ３The main component is Si). Preferably, the soft portion has a multiphase structure, and more specifically, a structure in which Mo compounds (e.g., Laves phase, μ phase, R phase) are dispersed in a matrix of Fe-containing phases. Whether or not the soft portion has such a morphology can be determined by observing a cross-section of the soft portion with a scanning electron microscope (SEM) and confirming whether or not it has a sea-island structure in which Mo compounds are dispersed island-like in a sea of ​​Fe-containing phases. Having such a configuration makes the soft portion moderately hard, and the surface strength of the particles increases, which can further improve the wear resistance of the coating. On the other hand, the hard portion mainly consists of Mo compounds (e.g., Laves phase, μ phase, R phase). Mo compounds are harder than the Fe-containing phase and have high lubricity. Therefore, by using hard particles in which at least a part of the surface of the soft portion is covered by the hard portion, it is possible to form a coating with a low coefficient of friction and excellent wear resistance. The structure of hard particles can be determined by microstructural observation using a scanning electron microscope (SEM) and analysis using X-ray diffraction (XRD). Whether or not the Fe-containing phase is dominant is determined by whether or not the area ratio of the Fe-containing phase to the total area of ​​the soft part exceeds 50% in the microstructural observation. Similarly, whether or not the Mo compound is dominant is determined by whether or not the area ratio of the Mo compound to the total area of ​​the hard part exceeds 50% in the microstructural observation.

[0021] Hard particles having such a structure can be manufactured by the gas atomization method. In the gas atomization method, molten metal obtained by melting raw metal is poured into a crucible with a hole in the bottom, and high-pressure inert gas (Ar or N) is applied to the molten metal flow that flows out of the hole. ２This method involves spraying molten metal (such as water) to scatter and solidify it, thereby obtaining metal powder. When the gas atomization method is applied to molten metal obtained by melting raw metal having the aforementioned composition, the Fe-containing phase solidifies, forming particulate soft parts. At this time, relatively fine particles (soft parts) with a diameter of about 10 to 30 μm remain suspended in the chamber, and droplets of molten metal adhere to the surface of these fine particles (soft parts) and solidify, forming hard parts mainly composed of Mo compounds. Of the parts formed by the solidification of the Fe-containing phase, relatively large particles do not remain suspended but immediately accumulate at the bottom of the chamber. Therefore, among the coarse powder finally obtained by the gas atomization method, the relatively large particles are those that have not formed hard parts. By classifying the coarse powder using a fine sieve of 350 mesh or more to remove the relatively large particles, hard particles with the desired structure can be obtained. On the other hand, the hard particles used in Comparative Example 1, described later, were produced by the water atomization method. In the water atomization method, metal powder is obtained by spraying high-pressure water onto a molten metal flow, causing it to splatter and solidify. The microstructure of a metal is determined by its composition and cooling rate, but with the water atomization method, the cooling rate is fast, so the soft and hard parts described above are not formed.

[0022] In the laminate according to this embodiment, the Vickers hardness of the soft part is set to HV １ [Unit: HV], Vickers hardness of the hard part in HV ２ When the unit is HV, then Equation 1: HV １ <HV ２ It is essential that the following conditions be met. HV １ and HV ２ From the viewpoint of further improving the abrasion resistance of the coating, formula 2a:HV ２ ≥ 1100, and Equation 3a: 100 ≤ HV ２ - HV １ It is preferable that the value ≤ 600 is satisfied; Equation 2b: HV ２ ≥ 1133, and equation 3b: 249 ≤ HV ２ - HV １ It is more preferable that ≤ 573 is satisfied; Equation 2c: HV ２ ≥ 1225, and equation 3c: 249 ≤ HV２ - HV １ It is even more preferable that the condition ≤ 315 is satisfied. When the laminate according to this embodiment is used as a sliding member, repeated sliding may cause the hard parts to peel off from the hard particles in the coating, and the hard parts to detach from the coating. HV ２ ≥ 1100, and HV ２ - HV １ If the value ≤ 600 is satisfied, the soft part has sufficient hardness, which can further improve the abrasion resistance of the coating. Also, HV ２ ≥ 1100, and 100 ≤ HV ２ - HV １ When this condition is met, the detachment of hard particles themselves from the coating can be suppressed. This prevents aggressive friction caused by hard particles detached from the coating, thus further improving the wear resistance of the coating. In this specification, the Vickers hardness will be the value measured by the method described in the examples below. The Vickers hardness can be controlled by the metal composition (the amount of Mo and Si added to Fe). For example, when the hard particles consist only of Fe, Mo, Si and unavoidable impurities, and the Mo content is 34% by mass or more, as the Si content increases, the amount of Mo compound dispersed in the matrix of the Fe-containing phase increases, and the Vickers hardness of the soft part tends to increase. Also, as the Mo content increases, the Vickers hardness of the hard part tends to increase.

[0023] As mentioned above, hard particles can be manufactured by the gas atomization method. To facilitate the formation of hard particles having predetermined soft and hard portions, the average particle diameter of the hard particles is preferably 40 μm or less, preferably 20 to 40 μm, and more preferably 25 to 35 μm. Furthermore, as shown in Figure 1, when the hard particles have a core-shell structure in which the soft portion constitutes the core and the hard portion constitutes the shell, the average diameter of the soft portion (core) is preferably 10 to 30 μm, and more preferably 15 to 25 μm. The average thickness of the hard portion (shell) is preferably 5 to 20 μm, and more preferably 5 to 10 μm. In this specification, the "particle diameter" of the hard particles refers to the maximum distance between any two points on the contour line of the particle when observed using a scanning electron microscope (SEM). Furthermore, the "diameter" of the soft part refers to the maximum distance between any two points on the contour line of the soft part when observing the cross-section of the particle using a scanning electron microscope (SEM). The average value for a given value refers to the arithmetic mean of a statistically significant number of values ​​(e.g., at least 200). The "average thickness" of the hard part refers to the value calculated by (average particle diameter - average diameter) ÷ 2.

[0024] The thickness of the coating in the laminate is not particularly limited, as it depends on the sliding member to which the laminate is applied, but it is preferably 0.05 to 5.0 mm, and more preferably 0.1 to 2.0 mm. When the thickness of the coating is within the above range, the rigidity of the coating and the adhesion between the substrate and the coating are good.

[0025] <Method for Manufacturing Laminates> The above laminate is manufactured by forming a film on a substrate using a cold spray method. That is, according to another embodiment of the present invention, a method for manufacturing a laminate comprising a substrate and a film formed on the substrate, comprising: using a cold spray device, a mixed particle of hard particles and Cu alloy particles is impacted onto the substrate under the conditions that the pressure of the working gas at the nozzle inlet in the chamber is 7 MPa or less and the temperature of the working gas is 1000°C or less, thereby forming the film on the substrate (hereinafter also referred to as the "film formation step"), wherein the hard particles contain Fe, Mo and Si, and the hard particles have a soft part mainly composed of an Fe-containing phase and a hard part mainly composed of a Mo compound that covers at least a part of the surface of the soft part, and the Vickers hardness of the soft part is HV １ [Unit: HV], the Vickers hardness of the hardened part is HV ２ When the unit is HV, then Equation 1: HV １ <HV ２ A method for manufacturing a laminate that satisfies the requirements is provided. The film formation process will be described below.

[0026] In the film formation process, a mixture of hard particles and Cu alloy particles is brought into contact with the substrate. The "hard particles" referred to here are hard particles used as raw materials before they form the film, but they are substantially the same as the hard particles contained in the film as described above. The Cu alloy particles are the particles that serve as the raw materials for the Cu alloy that constitutes the matrix in the film as described above. The average particle diameter of the Cu alloy particles is not particularly limited, but it is preferably 5 to 50 μm, more preferably 7 to 30 μm, and even more preferably 10 to 25 μm. The average particle diameter of the hard particles used as raw materials is substantially the same as the average particle diameter of the hard particles contained in the film. The mixing ratio of hard particles to Cu alloy particles in the mixture is adjusted by those skilled in the art so that the area ratio of the Cu alloy in the cross-section of the film is a desired value.

[0027] The conditions for impacting a mixture onto a substrate using a cold spray device are that the pressure of the working gas at the nozzle inlet in the chamber is 7 MPa or less, and the temperature of the working gas is 1000°C or less. Under these conditions, a film in which hard particles are dispersed in a matrix containing a Cu alloy can be easily formed. The working gas pressure is preferably 4 to 7 MPa, and more preferably 4 to 6 MPa. The working gas temperature is preferably 400 to 800°C, and more preferably 600 to 800°C. The type of working gas is not limited, but examples include nitrogen and helium.

[0028] The following embodiments are also included in the scope of the present invention: 1. A laminate comprising a substrate and a film formed on the substrate, wherein the film is composed of hard particles dispersed in a Cu alloy matrix, the hard particles containing Fe, Mo and Si, and the hard particles having a soft portion mainly composed of an Fe-containing phase and a hard portion mainly composed of a Mo compound covering at least a part of the surface of the soft portion, and the Vickers hardness of the soft portion being HV １ [Unit: HV], the Vickers hardness of the hardened part is HV ２ When the unit is HV, then Equation 1: HV １ <HV ２ Laminate that satisfies the following conditions; Item 2: The HV １ [Unit: HV] and the aforementioned HV ２ [Unit: HV] is, Equation 2a: HV ２ ≥ 1100, and Equation 3a: 100 ≤ HV ２ - HV １ ≤ 600 (preferably, formula 2b: HV ２ ≥ 1133, and equation 3b: 249 ≤ HV ２ - HV １ Satisfying ≤ 573; more preferably, formula 2c: HV ２ ≥ 1225, and equation 3c: 249 ≤ HV ２ - HV １A laminate according to item 1, satisfying ≤ 315; item 3: A laminate according to item 1 or 2, wherein the Si content in the hard particles is 4% by mass or more; Item 4: The laminate according to any one of items 1 to 3, wherein the hard particles consist only of Fe, Mo, Si and unavoidable impurities, and the composition of the hard particles is Mo: 28 to 45 mass%, Si: 1 to 10 mass%, with the remainder being Fe and unavoidable impurities (preferably Mo: 30 to 42 mass%, Si: 1.5 to 8 mass%, with the remainder being Fe and unavoidable impurities; more preferably Mo: 32 to 38 mass%, Si: 3 to 7 mass%, with the remainder being Fe and unavoidable impurities; even more preferably Mo: 32.5 to 37 mass%, Si: 4 to 6 mass%, with the remainder being Fe and unavoidable impurities; particularly preferably Mo: 32.5 to 35.5 mass%, Si: 4 to 4.8 mass%, with the remainder being Fe and unavoidable impurities); Item 5: The laminate according to any one of items 1 to 4, wherein the average particle diameter of the hard particles is 20 to 40 μm; Item 6: A laminate according to any one of Items 1 to 5, wherein the hard particles have a core-shell structure in which the soft portion constitutes the core and the hard portion constitutes the shell, the average diameter of the soft portion being 10 to 30 μm and the average thickness of the hard portion being 5 to 20 μm; Item 7: A sliding member having the laminate according to any one of Items 1 to 6 in its sliding portion; Item 8: A method for manufacturing a laminate comprising a substrate and a film formed on the substrate, comprising: using a cold spray device, in which a mixed particle of hard particles and Cu alloy particles is impacted onto the substrate under the conditions that the pressure of the working gas at the nozzle inlet in the chamber is 7 MPa or less and the temperature of the working gas is 1000°C or less, thereby forming the film on the substrate, wherein the hard particles contain Fe, Mo and Si, and the hard particles have a soft portion mainly composed of an Fe-containing phase and a hard portion mainly composed of a Mo compound that covers at least a part of the surface of the soft portion, and the Vickers hardness of the soft portion is HV １ [Unit: HV], the Vickers hardness of the hardened part is HV ２ When the unit is HV, then Equation 1: HV １ <HV ２ A method for manufacturing a laminate that satisfies the requirements.

[0029] The present invention will be described in more detail below with reference to examples. However, the technical scope of the present invention is not limited to the following examples.

[0030] <Examples of Laminate Fabrication> [Example 1] Mixed particles were obtained by mixing hard particles (composition: Fe-35.5Mo-4.8Si, structure: core-shell structure, average particle diameter (D50): 31 μm, average particle diameter of the soft part (core): 18.6 μm, average thickness of the hard part (shell): 6.2 μm, fabrication method: gas atomization) and Cu alloy particles (composition: Cu-2.9Ni-0.7Si, average particle diameter (D50): 10 μm) in a volume ratio of hard particles:Cu alloy particles = 30:70. As base materials, base material A (made of aluminum) in the shape of a valve seat and base material B (circular test piece for SRV testing) were prepared. A film (thickness: 1 mm) was formed on the surface of base material A and base material B by the cold spray method under the following conditions to obtain laminate A and laminate B of this example, respectively. Furthermore, since the hard particles have a higher hardness than the Cu-containing alloy, they maintain their shape even within the coating compared to before cold spraying; Cold spraying equipment: PCS-1000 manufactured by Plasma Giken Kogyo Co., Ltd. Working gas: Nitrogen Working gas temperature: 450℃ Working gas pressure: 4MPa Spray distance: 20mm.

[0031] [Example 2] Laminates A and B of this example were obtained, except that particle 2 (composition: Fe-32.5Mo-4.8Si, structure: core-shell structure, average particle diameter (D50): 28 μm, average particle diameter of the soft part (core): 16.8 μm, average thickness of the hard part (shell): 5.6 μm, manufacturing method: gas atomization method) was used as the hard particles.

[0032] [Example 3] Laminates A and B of this example were obtained, except that particle 3 (composition: Fe-34Mo-4Si, structure: core-shell structure, average particle diameter (D50): 35 μm, average particle diameter of the soft part (core): 21 μm, average thickness of the hard part (shell): 7 μm, manufacturing method: gas atomization method) was used as the hard particle.

[0033] [Example 4] Laminates A and B of this example were obtained, except that particle 4 (composition: Fe-32.5Mo-3.3Si, structure: core-shell structure, average particle diameter (D50): 27 μm, average particle diameter of the soft part (core): 16.2 μm, average thickness of the hard part (shell): 5.4 μm, manufacturing method: gas atomization method) was used as the hard particle.

[0034] [Example 5] Laminates A and B of this example were obtained, except that particle 5 (composition: Fe-35Mo-3.0Si, structure: core-shell structure, average particle diameter (D50): 33 μm, average particle diameter of the soft part (core): 19.8 μm, average thickness of the hard part (shell): 6.6 μm, manufacturing method: gas atomization method) was used as the hard particle.

[0035] [Comparative Example 1] Laminates A and B of this example were obtained, except that comparative particle 1 (composition: Fe-35Mo-1.4Si, average particle diameter (D50): 32 μm, manufacturing method: water atomization method), which does not have a soft portion or a hard portion, was used as the hard particle.

[0036] <Evaluation of the Laminate> [Observation of the Film Cross Section] Using laminate B (circular test piece for SRV testing) prepared above, the cross section of the film was observed with a scanning electron microscope (SEM). From the obtained observation images, it was confirmed that the film has a sea-island structure in which hard particles are dispersed in an island-like manner within a sea made of Cu alloy.

[0037] [Wear Test] The laminate A (valve seat) prepared as described above was subjected to an wear test under the following conditions. Using a shape measuring device, the shape of laminate A was obtained before and after the test, and the amount of wear was measured at four locations. The wear resistance was evaluated using the arithmetic mean of the obtained values. The results are shown in Table 1 below; Test method: Valve seat single-piece tap wear test (Test device: Takachiho Seiki Co., Ltd.) Test temperature: 300℃ Number of seating cycles: 1.44 million (3000 cpm × 8 Hr) Counter material (valve): JIS SUH35.

[0038] [Friction Coefficient Measurement] The friction coefficient of laminate B (circular test piece for SRV test) prepared as described above was measured under the following conditions. The results are shown in Table 1 below; Test method: SRV test (Test equipment: SRV5 manufactured by OPTIMOL instruments Inc.) Test temperature: 150℃ Load: 400N Frequency: 50Hz Sliding width: 2.5mm.

[0039] <Vickers Hardness Measurement> Using laminate B after the friction coefficient measurement described above, the Vickers hardness of the soft and hard parts of the hard particles contained in the coating was measured using the following method. The surface of the coating was buffed to a mirror finish for 15 minutes using a colloidal silica suspension, and then a hardness test was performed using a Vickers hardness tester. The load was set to 10 g, and measurements were taken at 10 points each for the hard and soft parts. The arithmetic mean of the obtained values ​​is shown in Table 1 below.

[0040]

[0041] As shown in Table 1, the laminate according to the present invention has a structure in which hard particles, each having a soft portion and a hard portion covering at least a part of the surface of the soft portion, are dispersed in a matrix containing a Cu alloy, resulting in a low coefficient of friction and excellent wear resistance.

[0042] Furthermore, comparing Examples 1 to 5, the Vickers hardness HV of the soft part is １ And, the Vickers hardness of the hard part HV ２ It can also be seen that wear resistance can be further improved by controlling these parameters within a predetermined range.

[0043] 10 hard particles, 11 soft part, 12 hard part.

Claims

1. A laminate comprising a substrate and a film formed on the substrate, wherein the film is composed of hard particles dispersed in a matrix containing a Cu alloy, the hard particles contain Fe, Mo and Si, and the hard particles have a soft portion mainly composed of an Fe-containing phase and a hard portion mainly composed of a Mo compound that covers at least a part of the surface of the soft portion, and the Vickers hardness of the soft portion is HV １ [Unit: HV], the Vickers hardness of the hardened part is HV ２ When the unit is HV, then Equation 1: HV １ <HV ２ A laminate that satisfies the requirements.

2. The HV １ [Unit: HV] and the HV ２ [Unit: HV] are expressed by Formula 2a: HV ２ ≧1100, and Formula 3a: 100≦HV ２ −HV １ ≦600. The laminate according to Claim 1 3. The aforementioned HV １ [Unit: HV] and the aforementioned HV ２ [Unit: HV] is, Equation 2b: HV ２ ≥ 1133, and equation 3b: 249 ≤ HV ２ - HV １ The laminate according to claim 1, satisfying ≤ 573.

4. The aforementioned HV １ [Unit: HV] and the aforementioned HV ２ [Unit: HV] is, Equation 2c: HV ２ ≥ 1225, and equation 3c: 249 ≤ HV ２ - HV １ The laminate according to claim 1, satisfying ≤ 315.

5. The laminate according to claim 1, wherein the Si content in the hard particles is 4% by mass or more.

6. The laminate according to claim 1, wherein the average particle size of the hard particles is 20 to 40 μm.

7. The laminate according to claim 1, wherein the hard particles have a core-shell structure in which the soft portion constitutes the core and the hard portion constitutes the shell, the average diameter of the soft portion is 10 to 30 μm, and the average thickness of the hard portion is 5 to 20 μm.

8. A sliding member having the laminate described in claim 1 at its sliding portion.

9. A method for manufacturing a laminate comprising a substrate and a film formed on the substrate, comprising: using a cold spray device, forming the film on the substrate by impacting a mixture of hard particles and Cu alloy particles onto the substrate under conditions where the pressure of the working gas at the nozzle inlet in the chamber is 7 MPa or less and the temperature of the working gas is 1000°C or less, the hard particles contain Fe, Mo and Si, the hard particles have a soft portion mainly composed of an Fe-containing phase and a hard portion mainly composed of a Mo compound that covers at least a part of the surface of the soft portion, and the Vickers hardness of the soft portion is HV １ [Unit: HV], the Vickers hardness of the hardened part is HV ２ When the unit is HV, then Equation 1: HV １ <HV ２ A method for manufacturing a laminate that satisfies the requirements.

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