Sliding components and their manufacturing methods, as well as methods for manufacturing rigid materials

Abstract

In a sliding member, a hard material is dispersed in a soft metal matrix to form a surface layer to improve its fatigue resistance. The sliding member has a substrate layer and a surface layer, wherein the surface layer has a metal matrix and a hard material dispersed in the matrix and which is harder than the matrix, the hard material having a slope in its hardness, the slope of which gradually decreases from the inside of the hard material to the surface.

Description

Technical Field

[0001] This invention relates to sliding components and their manufacturing methods, as well as improvements to the manufacturing methods of rigid materials. Background Technology

[0002] Sliding components typically have a substrate layer and a surface layer, with the surface layer supporting the component being slidable. To ensure sliding performance, this surface layer is usually formed of a soft metallic material.

[0003] The surface layer formed by soft metallic materials has problems with its wear resistance, so people have considered dispersing hard materials (hard particles) in it to improve wear resistance.

[0004] However, if there is a significant hardness difference between the metal matrix constituting the surface layer and the hard material dispersed within it, stress concentration can easily occur at the interface. As a result, the hard material may detach from the metal matrix of the surface layer. If the hardness difference between the hard material and the metal matrix is ​​large, when an external force applied to the surface layer is transmitted through the metal matrix to the hard material, it bounces off the hard surface of the hard material, concentrating at the interface with the relatively soft metal matrix. As a result, the structure of the metal matrix at this interface may collapse, leading to the detachment of the hard material.

[0005] Therefore, it has been proposed to mitigate stress concentration by coating the hard material with a material whose hardness falls between that of the hard material and the metal matrix (see Patent Document 1). If such a material with intermediate hardness is used to coat the hard material, stress concentration at the interface with the metal matrix can be prevented because a portion of the stress is absorbed by the coating material. This prevents the collapse of the metal matrix at the interface, thus preventing the hard material from detaching and improving the fatigue resistance of the sliding component.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 7-238331 Summary of the Invention

[0009] The technical problem that the invention aims to solve

[0010] With the evolution of internal combustion engines, exemplified by the start-stop technology or miniaturization of motor vehicle engines, there is a tendency for the load on sliding components to increase.

[0011] Therefore, higher requirements are placed on sliding components, namely, improving their fatigue resistance while ensuring the sliding properties of the metal matrix.

[0012] Here, although the technology proposed in Patent Document 1 can prevent the hard material from falling off by covering the hard material with a relatively soft metal, modern sliding components require a higher level of anti-falling effect.

[0013] Furthermore, the technology proposed in Patent Document 1 uses a metal film to coat hard materials, thus increasing the particle size. According to an embodiment in Patent Document 1, the thickness of the coated metal layer is at least 15 μm. On the other hand, the surface layer of sliding components used in motor vehicle engines typically has a film thickness of several to tens of μm. Therefore, hard materials of the size proposed in Patent Document 1 cannot be used for the surface layer of such a thin film. This is because the hard material may protrude from the surface layer, compromising the required softness of the surface layer.

[0014] Technical solutions adopted to solve technical problems

[0015] To solve the above problems, the inventors, after careful research, discovered that it is sufficient to soften the surface of the hard material itself. Since the surface of the hard material is softened, it is not necessary to coat it with another metal film as proposed in Patent Document 1. This prevents the hard material from becoming too large.

[0016] The first aspect of the present invention is defined as follows. That is,

[0017] A sliding component,

[0018] The sliding component has a substrate layer and a surface layer, wherein...

[0019] The surface layer comprises a metal matrix and a hard material dispersed in the matrix that is harder than the matrix, the hard material having a slope in its hardness, the slope of hardness gradually decreasing from the inside of the hard material toward the surface.

[0020] Because the sliding member specified in aspect one has an inclination in its hardness, which gradually decreases from the inside of the hard material towards the surface, the hard material itself retains its original harder portion on the inside. This ensures that the hard material originally provides the required wear resistance to the surface layer. Furthermore, since the hard material is softened on the surface side, the hardness difference at the interface with the metal matrix is ​​mitigated. This also reduces stress concentration at the interface, preventing the hard material from detaching from the metal matrix. Therefore, the fatigue resistance of the sliding member is improved.

[0021] Figure 1 The diagram shown is a schematic of the sliding member 1 of the present invention.

[0022] The sliding member 1 consists of a substrate layer 3 made of metal materials such as steel and a surface layer 5 stacked thereon. The surface layer 5 is composed of a hard material 7 dispersed in a soft metal matrix 6.

[0023] Figure 2 The image shown is a conceptual diagram of the hard material 7.

[0024] In this example, the hard material 7 is divided into two regions: a relatively hard region A and a relatively soft region B. Referring to the third aspect described later, the concentration of the second metallic material in hard region A is less than 9%, while the concentration of the second metallic material in soft region B is greater than 9%. The X in the figure shows the interface between the two regions.

[0025] The second aspect of the present invention is defined as follows.

[0026] In the sliding member specified in the first aspect, the surface hardness of the hard material is equal to the hardness of the metal matrix.

[0027] Such a sliding member effectively prevents stress concentration at the interface between the hard material and the metal matrix. Equal hardness here means that the stress on the interface is substantially evenly distributed between the two (the surface of the hard material and the metal matrix), including cases where there are differences in the physical parameters indicating hardness between the two.

[0028] The third aspect of the present invention is specified as follows. That is, in the sliding member specified in the first or second aspect, the rigid material comprises a first metal material and a second metal material, the second metal material being softer than the first metal material, and the concentration of the second metal material having an inclination that gradually increases from the inside of the rigid material toward the surface.

[0029] The sliding member specified in the third aspect is inclined at the concentration of the soft second metallic material. This allows for the achievement of the inclination at the hardness specified in the first aspect.

[0030] Furthermore, the presence of a third metallic material is not excluded as a material for forming the hard object. If the hardness gradient specified in the first aspect is ensured by the concentration distribution of the first and second metallic materials, the concentration distribution of the third metallic material is not particularly limited. This third metallic material is also preferably softer than the first metallic material, just like the second metallic material, and its concentration distribution is the same as that of the second metallic material (the concentration gradient gradually increases from the inside of the hard object to the surface).

[0031] The fourth aspect of the present invention is specified as follows. That is, in the third aspect, the metal matrix and the second metal material are the same or identical materials.

[0032] This makes it easier to make the surface hardness of the hard material equal to the hardness of the metal matrix. Furthermore, the adhesion of a hard material with a second metallic material to a metal matrix composed of the same or identical metal is improved, more effectively preventing it from detaching. Here, "identical metal" refers to alloys or similar materials containing the same metallic elements.

[0033] The fifth aspect of the present invention is specified as follows: In the sliding member specified in the third or fourth aspect, the area ratio of the region in the hard material where the proportion of the second metallic material is 9% or less is 1% or more and 35% or less.

[0034] The sliding member specified in aspect 5 of this designation contains a hard region A, where the proportion of the second metal material (1-35%) is less than 9% by mass. This ensures the hardness required for maintaining wear resistance. On the other hand, the remaining regions are soft regions B, where the second metal material constitutes more than 9% by mass. Because this soft region B is present in appropriate amounts on the surface of the hard material, therefore… Figure 3 As shown in Figure B, a portion of the external force P applied to the surface layer is absorbed by the soft region B. Therefore, stress concentration at the interface between the hard material 7 and the metal matrix 6 is effectively prevented.

[0035] On the other hand, if the area ratio of the second metallic material is less than 9% by mass (hard region A) and the area ratio is less than 1%, then as Figure 3 As shown in Figure A, the hard region A decreases in size. Therefore, with... Figure 3 Compared to the configuration shown in B, there is a tendency for a decrease in the wear resistance imparted to the surface layer.

[0036] Furthermore, if the area ratio of the second metallic material is less than 9% by mass (hard region A) is greater than 35%, then as Figure 3 As shown in Figure C, the hard region A becomes larger. As a result, in this hard region A, the external force P applied to the surface layer tends to bounce and concentrate at the interface with the metal matrix. That is, with... Figure 3 Compared to the configuration shown in B, the stress concentration prevention function there tends to be reduced.

[0037] Here, the ratio of the second metallic material is expressed as mass% obtained by the common elemental analysis method.

[0038] Furthermore, the area ratio of the region can be obtained as follows.

[0039] Imagined pixels are defined on the cross-section of the hard object. Elemental analysis is performed on each pixel, and the pixel count within the range (below 9% by mass) for the ratio of the second metallic material is displayed. The ratio of this number to the total number of pixels constituting the hard object is denoted as the area ratio.

[0040] The sixth aspect of the present invention is specified as follows. That is, in the sliding member specified in the fifth aspect, the distance from the surface of the hard material to the region where the ratio of the second metal material is 9% by mass or less is 0.07 μm or more.

[0041] In the sliding member specified in aspect 6, the soft region B, i.e., the region where the proportion of the second metallic material is greater than 9% by mass, exists on the surface side of the hard material with a thickness of 0.07 μm or more (see reference). Figure 4 By ensuring this soft region B, stress concentration at the interface between the hard material and the metal matrix can be more effectively prevented.

[0042] The method for measuring the distance L from the surface of the hard object 7 to the aforementioned specified area is described in detail in the Embodiments section.

[0043] Furthermore, and more preferably, the thickness of the soft region B is uniform throughout the hard material. In other words, the hard region A is located at the center of the hard material. This allows for the uniform mitigation of stresses borne by the hard material from all directions.

[0044] The seventh aspect of the present invention is specified as follows.

[0045] A method for manufacturing a sliding component.

[0046] The sliding member in this manufacturing method has a substrate layer and a surface layer. The manufacturing method includes:

[0047] The lamination step involves laminating a precursor layer of the surface layer onto the substrate layer, in which particles of a first metallic material, harder than the metallic matrix, are dispersed within the metallic matrix.

[0048] The heating step involves heating the precursor layer to allow the material of the metal matrix to diffuse into the particles of the first metal material.

[0049] In the manufacturing method of aspect 7, as specified herein, during the heating step, atoms of a relatively soft metal matrix diffuse into the particles of a first metal material. The degree of diffusion is controlled by adjusting the temperature or the time. This results in a state where the diffusion amount of the metal matrix on the surface side of the particles of the first metal material is greater than the diffusion amount on the inner side. That is, if the material of the diffused metal matrix is ​​considered the second metal material, then in the granular hard material composed of the first metal material, an inclination occurs in the concentration of the second metal material, which is softer than the first metal material, and this inclination gradually increases from the inner side of the hard material towards the surface.

[0050] The eighth aspect of the present invention is as follows: In the manufacturing method specified in the seventh aspect, during the precursor layer formation step, a second metal material serving as the metal matrix and the first metal material are simultaneously plated together, such that particles of the first metal material are dispersed within the second metal material.

[0051] After the precursor layer is formed and before the heating step is performed, a third metal material stacking step is further performed. Here, the third metal material is a metal different from the first and second metal materials, which can diffuse into either the first or second metal materials by heating.

[0052] The manufacturing method specified in aspect 8 eliminates the need for separate preparation of particles composed of the first metallic material. Therefore, the process of dispersing these particles in a metal matrix is ​​eliminated, simplifying the manufacturing process.

[0053] In the above context, the first and second metallic materials do not substantially form a solid solution. Here, "not forming a solid solution" means that the two metals will not mix due to contact or mere heating. Furthermore, it also means that even if both metallic materials are ionized and stacked (i.e., plated) on the same surface, the two materials will not mix.

[0054] On the other hand, the third metallic material can form a solid solution with the first metallic material and the second metallic material.

[0055] The ninth aspect of the present invention is as follows: In the manufacturing method specified in the eighth aspect, the third metallic material is softer than the first metallic material.

[0056] In the manufacturing method of aspect 9 specified in this way, since the third metal material is also softer than the first metal material, it is easier to set the concentration of the soft metal material in the first metal material when combined with the second metal material.

[0057] The tenth aspect of the present invention relates to a method for manufacturing a hard object to which the present invention applies. That is...

[0058] A method for manufacturing a hard object.

[0059] The hard material in this manufacturing method comprises a first metal material and a second metal material, wherein the second metal material is softer than the first metal material, and the concentration of the second metal material has a gradient, which gradually increases from the inside of the hard material towards the surface.

[0060] This allows the particles of the first metal material to come into contact with the melt of the second metal material.

[0061] The concentration distribution of the second metal material in a hard material composed of particles of the first metal material can be controlled by adjusting the contact conditions (temperature, time, stirring). Contact methods include impregnation and molten flow.

[0062] The eleventh aspect of the present invention is specified as follows. That is...

[0063] A method for manufacturing a hard object.

[0064] The hard material in this manufacturing method comprises a first metallic material, a second metallic material, and an inorganic porous body. The second metallic material is softer than the first metallic material, and the concentration of the second metallic material exhibits a gradient, gradually increasing from the inside of the hard material towards the surface.

[0065] The inorganic porous body is immersed in the melt of the first metal material, and then brought into contact with the melt of the second metal material, thereby causing the second metal material to diffuse into the first metal material.

[0066] In the method for manufacturing a hard material as specified in aspect 11, an inorganic porous body that will form the skeleton of the hard material is first impregnated in a melt of a first metallic material to adsorb it. This yields particles of the first metallic material with the inorganic porous body internally absorbed. Then, by contacting these particles with a melt of a second metallic material, the second metallic material diffuses into the particles. Furthermore, the concentration distribution of the second metallic material diffusing into the first metallic material constituting the hard material can be controlled by adjusting the contact conditions (temperature, time, stirring). Contact methods include impregnation and melt flow.

[0067] The 12th aspect of the present invention is specified as follows. That is,

[0068] A method for manufacturing a sliding component.

[0069] The method for manufacturing the sliding member uses a hard material obtained by the method for manufacturing a hard material as described in aspect 10 or 11, comprising:

[0070] Steps for preparing the substrate layer

[0071] The plating step involves depositing a metal matrix material onto the surface of the substrate layer, during which the hard material is mixed into the bubbling gas in the plating bath.

[0072] By using this prescribed manufacturing method, hard materials can be evenly dispersed in the metal matrix. Attached Figure Description

[0073] Figure 1 The diagram shown is a schematic of the sliding member of the present invention.

[0074] Figure 2 The diagram shown is also of a hard material.

[0075] Figure 3 The diagram shows the relationship between the ratio of hard region A to soft region B in a hard material and its properties.

[0076] Figure 4 The diagram shows the relationship between the distance from the surface of a hard material to the hard region A and its properties. Detailed Implementation

[0077] The present invention will now be described in more detail based on its embodiments.

[0078] The substrate layer that constitutes the sliding component is usually made of metallic material.

[0079] In a bearing, which serves as an example of a sliding component, a copper-based bearing alloy layer is laminated onto a steel lining metal layer. Sometimes, an intermediate layer composed of materials such as Ag or Ni is also formed on the bearing alloy layer.

[0080] The surface layer constituting the sliding component uses a soft metal as a matrix, in which hard substances are dispersed.

[0081] Materials that can be used as a metal matrix include indium (In), tin (Sn), lead (Pb), bismuth (Bi), and antimony (Sb). The thickness of this metal matrix ranges from 1 μm to 50 μm.

[0082] The average particle size of the hard material dispersed in the metal matrix can be from 0.2 μm to 50 μm. Preferably, the average particle size is shorter than the film thickness of the surface layer, from 1 μm to 5 μm. Furthermore, the doping amount of the hard material relative to the metal matrix is ​​preferably from 0.5% to 60.0% by volume, more preferably from 5.0% to 40.0% by volume.

[0083] The average particle size, mixing amount, and material of these hard materials can be appropriately selected according to the application of the sliding component.

[0084] Hard materials dispersed in the surface layer have an inclination in their hardness, which gradually decreases from the inside to the surface.

[0085] By gradually reducing the hardness, the external forces borne by the surface layer can be absorbed efficiently. In other words, if the change in hardness is step-like in the radial direction, the external force may rebound at the interface where the hardness changes, which is undesirable. Furthermore, forming a step-like hardness in tiny hard materials is very difficult.

[0086] A gradual change in the material properties (chemical properties) of a hard material can impart a continuous gradient of hardness. Furthermore, a gradual change in the physical properties of a hard material can also impart a gradient of hardness.

[0087] To achieve a gradual change in the material composition of the hard material, a material softer than the substrate material diffuses from the surface of the particles constituting the hard material. In this way, a diffusion state in which the concentration of the soft material gradually increases from the inside to the surface can be achieved within the particles composed of the hard material. As a diffusion method, it is preferable to diffuse the soft material into the substrate material by bringing the two into contact under high-temperature conditions (the substrate is solid, and the soft material is liquid). Alternatively, diffusion can also be achieved by physically atomizing the latter's particles into the former.

[0088] The tilt of hardness in a hard material can form either throughout the entire material or in a portion thereof. Furthermore, viewed from the center of the hard material, the tilt of hardness can be uniform or non-uniform. Here, uniformity means that the hardness is the same at equidistant points when viewed from the center.

[0089] Even when a hardness bias is formed throughout the hard material, since the explicit function of the hard material is to improve wear resistance, there needs to be a portion within the hard material that maintains its original hardness. In this specification, such a portion is designated as hard region A. For example, when the hard material is composed of a first metallic material having its original hardness and a relatively soft second metallic material, the region where the ratio of the second metallic material to the total hard material is 9% by mass or less is designated as hard region A.

[0090] Because this hard region A occupies a specified size within the hard material, it can impart the original wear-resistant properties to the hard material. The size of this hard region A can be appropriately selected based on the hardness of the hard region A itself or the intended use of the sliding component.

[0091] In this specification, the proportion occupied by the hard region A is defined by the area ratio of the desired cross-section, which is preferably 1% or more. The method for calculating the area ratio is not particularly limited; for example, imaginary pixels can be set in the desired cross-section of the hard object, elemental analysis can be performed on each pixel, and the pixel count within the aforementioned range (9% by mass or less) can be displayed for the proportion of the second metal material. The ratio of this number to the total number of pixels in the hard object is denoted as the area ratio.

[0092] From this perspective, the area ratio of hard region A is more preferably above 20%.

[0093] If the proportion of hard region A in a hard material becomes too large, that is, if its area ratio becomes too large, it will affect the stress relief function. Therefore, in this invention, the area ratio of hard region is preferably 35% or less.

[0094] From this perspective, the area ratio of hard region A is more preferably below 30%.

[0095] To impart variations in the material properties of a hard object, it is preferably formed from two or more metallic materials. The first metallic material possesses the hardness originally required for the hard object. The second metallic material is selected to be a material that is softer than the first metallic material, and by impregnating it from the surface side into the particles composed of the first metallic material, a tilt in the concentration of the second metallic material (i.e., a tilt in hardness) is formed.

[0096] The first metallic material here can be metals such as copper (Cu), silver (Ag), manganese (Mn), and nickel (Ni), or alloys of these metals. This first metallic material is harder than the material of the metallic matrix.

[0097] The second metallic material is selected as a material that is softer than the first metallic material and capable of diffusing into the first metallic material. Examples of such a second metallic material include metals such as In, Sn, Pb, Bi, Sb, and Zn, and their alloys.

[0098] In addition to the first and second metallic materials, a third component can be added to the hard material.

[0099] A third metallic material may be added as a third component. This third metallic material may diffuse into the first or second metallic material, or it may exist alone.

[0100] Inorganic materials can be added as a third component. For example, the heat resistance of a hard material can be improved by embedding porous silica within it.

[0101] The shape of the hard object can be chosen arbitrarily. It is not limited to... Figure 2 The spherical shape shown can also be an ellipsoid or a rod shape.

[0102] The following describes a method for forming a surface layer on a substrate layer.

[0103] <Method for preparing slanted particles, i.e., hard materials, separately from the metal matrix>

[0104] Prepare particles composed of a first metallic material that is harder than the metallic matrix.

[0105] A melt is prepared by melting a second metal material that is softer than the first metal material and can form a solid solution with it. The melt of the second metal material is maintained at a specified temperature, and particles of the first metal material are immersed in it and stirred for a specified time and using a specified method. This yields particles in which the second metal material diffuses from the surface of the particles composed of the first metal material into their interior, and where the second metal material exhibits a concentration inclination, i.e., an inclination in hardness—that is, hard material.

[0106] When a metal matrix is ​​formed on the surface of a substrate layer by electroplating, the hard material is forcibly supplied to the substrate layer side, causing the hard material to be absorbed into the metal matrix and dispersed.

[0107] In the above description, the hard material may contain porous inorganic materials such as porous silica as a third material. In this case, particles of the first metal material with pre-embedded porous inorganic material are prepared by impregnating the porous inorganic material into the melt of the first metal material, and then impregnating them into the melt of the second metal material as described above.

[0108] <Methods for co-deposition of hard materials into a metal matrix>

[0109] Prepare a first metallic material (e.g., Cu) to ensure the hardness of the hard object, and a second metallic material (e.g., Bi) that is softer than the first metallic material and does not form a solid solution with it. The second metallic material becomes the metallic matrix.

[0110] Using a first metal material and a second metal material as plating sources, electrolytic plating is simultaneously performed on the surface of the substrate layer. Since the two metal materials do not form a solid solution, by adjusting the plating conditions (methanesulfonic acid bath, Cu concentration (g / L) in the bath, bath temperature, current density, and storage time from the end of bath adjustment to the time of plating), the resulting plating layer (the precursor layer of the surface layer) is made such that the first metal material is dispersed in a granular form with the second metal material as the matrix.

[0111] The ratio of the first metal material to the second metal material can be arbitrarily designed according to the characteristics required by the sliding member. For example, the preferred volume ratio is 1:1.5 to 1:10 for the first metal material to the second metal material.

[0112] On the precursor layer thus obtained, a layer of a third metal material (e.g., Sb) that can form a solid solution with the first and second metal materials is formed by electrolytic plating.

[0113] The ratio of the third metal material to (the first metal material + the second metal material) can be arbitrarily designed according to the characteristics required by the sliding component. For example, the preferred volume ratio is the former (the third metal material): the latter (the first metal material + the second metal material) = 1:3 to 1:15.

[0114] If this laminate is heated to a specified temperature and maintained for a specified time, a third metal material is introduced, and the second metal material diffuses together with the third metal material within the granular first metal material. This results in a state where a hard material is dispersed within the metal matrix composed of the second metal material. Since this hard material is formed by the diffusion of the relatively soft second and third metal materials from the surface side of the hard first metal material, the second and third metal materials, which are softer than the first metal material, diffuse towards it with a concentration gradient, which gradually increases from the inside to the surface. Here, the third metal material is preferably softer than the first metal material.

[0115] In the above description, the metal matrix and other layers are formed by electroplating, but they can also be formed by sputtering and other methods.

[0116] Example

[0117] The sliding member in the embodiment is, for example, Figure 1 The cross-sectional structure is shown. More specifically, a bimetallic strip is manufactured by lining a copper-based bearing alloy layer on a copper liner metal, and forming the bimetallic strip into a semi-cylindrical or cylindrical shape. Subsequently, the surface of the bearing alloy layer is drilled and surface-finished. Afterward, the surface of the semi-cylindrical or cylindrical shape is cleaned (electrolytic degreasing + acid cleaning). This forms the substrate layer 3 (thickness: 1.5 mm).

[0118] A surface layer (approximately 15 μm) is then laminated on the upper surface of the substrate layer 3 obtained therefrom.

[0119] The surface layers of Examples 1 to 3 are formed as follows.

[0120] Prepare particles composed of a first metallic material (average particle size: 3.6 μm), immerse them in a melt composed of a second metallic material for 1 hour, and stir. This allows the second metallic material to diffuse into the particles composed of the first metallic material. The average particle size of the particles composed of the first metallic material is referenced from the material supplier's catalog (hereinafter the same).

[0121] When electroplating a metal matrix material onto a substrate layer, a hard material obtained in this way is supplied to the vicinity of the substrate layer. The method of supplying the hard material is to entrap the hard material in the supplied gas while bubbling the plating bath.

[0122] In addition, in Comparative Examples 1 to 3, alloy particles composed of a first metal material and a second metal material were prepared, and the alloy particles were rolled in in the same manner as described above during electrolytic plating of the metal matrix material.

[0123] The surface layers of Examples 4 to 9 are prepared as follows.

[0124] Prepare a Cu plating source as the first metal material, a Bi plating source as the second metal material, and an Sb plating source as the third metal material.

[0125] The surface of the substrate layer is used as the coating surface, and electrolytic plating is performed using Cu plating source and Bi plating source together.

[0126] In this way, a precursor layer (13 μm) for the surface layer is formed on the surface of the substrate layer. This precursor layer is in a co-depositional state of Cu particles with Bi as the metal matrix. The volume ratio of the two is Cu:Bi = 7:13.

[0127] Subsequently, an Sb layer (2 μm) was deposited on the surface of the precursor layer using an Sb plating source.

[0128] The laminate obtained in this way was heat-treated according to the conditions in Table 2.

[0129] Furthermore, it goes without saying that the heat treatment can be arbitrarily selected based on the materials chosen or the conditions required for the surface layer.

[0130] In the laminate heated by this heat treatment, Sb diffuses into the forebody layer, concentrates in the granular Cu, and simultaneously diffuses into it. This is because Sb has better compatibility (higher reactivity) with Cu compared to Bi. It is assumed that when Sb diffuses into the Cu particles, it mixes with the surrounding Bi. As a result, as shown in Table 1, in addition to Sb, Bi also diffuses into the Cu particles.

[0131] In Comparative Example 4-1, alloy particles composed of Cu, Bi, and Sb were prepared, and Bi and Sb were used as plating sources to form a surface layer in the same manner as in Comparative Examples 1 to 3.

[0132] In Comparative Example 4-2, the precursor layer was not stacked with Sb, and the material was heated under the same conditions as in Example 4 (140°C × 5 hours (in air)). No diffusion of Bi material into the hard Cu material was observed.

[0133] Table 1 shows the test results of the sliding components of each embodiment and comparative example.

[0134] [Table 1]

[0135]

[0136] [Table 2]

[0137]

[0138] In Table 1, compared with the hard materials of Comparative Examples 1 to 4, which did not have a hardness tilt, the fatigue resistance of the hard materials of Examples 1 to 4, which had a hardness tilt, was improved.

[0139] Furthermore, the results of Examples 4 and 5 and Examples 6 to 9 show that if the area ratio of the hard region is 1 to 35%, an improvement in fatigue resistance can be observed.

[0140] Furthermore, a comparison between Example 6 and Example 9 shows that if the distance L from the surface of the hard material to the hard region A is 0.07 μm or more, an improvement in fatigue resistance can be observed.

[0141] In Table 1, the area ratio of the hard region A is obtained as follows.

[0142] First, define the interface between the substrate layer and the surface layer.

[0143] The cross-section of the sliding component was observed using an electron microscope. Ten measurement points were set at equal intervals along the sliding direction on the outermost surface of the sliding component. Ten vertical lines perpendicular to the outermost surface were drawn from these points. The length of each vertical line up to its intersection with the substrate layer was then measured; this length represents the thickness of the surface layer, and its average value was calculated. If any of the measured surface layer thicknesses showed an average value greater than ±5%, these were removed as outliers, and the average value was recalculated.

[0144] This outlier primarily occurs when the substrate material and the hard material in the surface layer are similar in material. Due to the characteristics of the measurement method itself, when the hard material is in contact with the substrate layer, it may sometimes be identified as surface roughness of the substrate layer, thus requiring detection as an outlier. Therefore, after defining the interface between the substrate layer and the surface layer, the area fraction of the region where the concentration of the second metal material is below 9% (hard region A) is calculated.

[0145] Elemental analysis was performed on the substrate layer and the surface layer defining the interface. The elemental analysis was performed using a JXA-8530F field emission electron probe microanalyzer (manufactured by NEC Corporation). The resolution of the elemental analysis was 0.05 μm × 0.05 μm per pixel. The concentration of the second metal material was then divided into three regions: a region with a concentration of 100%–95% (the metal matrix region), a region with a concentration less than 95%–greater than 9% (soft region B), and a region with a concentration of 9%–0% (hard region A). The area fraction of the region with a concentration of 9%–0% (hard region A) was calculated using the following formula.

[0146] The area ratio of the region (hard region A) where the concentration of the second metallic material in the hard material is 9%–0% =

[0147] (Area of ​​the region with a concentration of 9-0% in the second metallic material (hard region A) × 100) / (Area of ​​the region with a concentration less than 95% to greater than 9% (soft region B) + Area of ​​the region with a concentration of 9-0% (hard region A)

[0148] The area here corresponds to the number of pixels.

[0149] In Table 1, the distance from the surface of the hard object to the hard region A is calculated as follows.

[0150] Image analysis was performed on the interface between the region with a Bi concentration of 100%–95% (the region of the metal matrix) and the region with a concentration of less than 95%–greater than 9% (soft region B), and this interface was designated as the first interface of the hard material. This first interface of the hard material was defined as the surface of the hard material. Similarly, the interface between the region with a Bi concentration of less than 95%–greater than 9% (soft region B) and the region with a Bi concentration of 9%–0% (hard region A) was detected and designated as the second interface of the hard material.

[0151] Then, the distance from the first interface to the second interface of the hard material was measured, and the minimum value was taken as the distance from the surface of the hard material to the region (hard region A) where the concentration of the second metal material is 9-0%.

[0152] The fatigue strength is obtained as follows.

[0153] The fatigue resistance was evaluated by conducting tests under the following conditions.

[0154] Bearing inner diameter: 53mm

[0155] Bearing width: 15mm

[0156] Speed: 3250rpm

[0157] Lubricating oil: VG22

[0158] Shaft material: S45C

[0159] Test duration: 20 hours

[0160] In the experiment, the surface pressure was increased by 5 MPa each time, and the maximum surface pressure that did not produce cracks was used as the evaluation value.

[0161] The maximum surface pressure is the value of the surface pressure just before cracks appear on the sliding surface. If cracks appear in the surface layer of the sample, it is considered fatigue.

[0162] This invention is not limited in any way by the description of the embodiments of the invention described above. Without departing from the description of the claims, this invention also includes various modifications that are readily apparent to those skilled in the art. Bearing mechanisms such as internal combustion engines using the sliding member of this invention can exhibit excellent sliding characteristics.

Claims

1. A sliding member, The sliding component has a substrate layer and a surface layer, wherein... The surface layer comprises a metal matrix and a hard material dispersed in the matrix that is harder than the matrix. The hard material consists of particles with an average particle size of 0.2 μm to 50 μm and has a continuous inclination in hardness, which gradually decreases from the center of the hard material toward the surface.

2. The sliding member as claimed in claim 1, wherein, The surface hardness of the hard material is equal to the hardness of the metal matrix.

3. The sliding member as described in claim 1 or 2, wherein, The hard material comprises a first metallic material and a second metallic material, the second metallic material being softer than the first metallic material, and the concentration of the second metallic material having a gradient that gradually increases from the center of the hard material toward the surface.

4. The sliding member as claimed in claim 3, wherein, The metal matrix is ​​the same as or the same type of material as the second metal material.

5. The sliding member as claimed in claim 3, wherein, In the hard material, the area of ​​the region where the proportion of the second metallic material is less than 9% by mass is more than 1% and less than 35%.

6. The sliding member as claimed in claim 5, wherein, In the hard material, the distance from its surface to the region where the ratio of the second metal material is less than 9% by mass is 0.07 μm or more.

7. A method for manufacturing a sliding component, The sliding component in this manufacturing method has a substrate layer and a surface layer. The manufacturing method includes: The precursor layer forming step involves stacking the precursor layer of the surface layer on the substrate layer, wherein particles of a first metallic material that are harder than the metallic matrix are dispersed within the metallic matrix. The heating step involves heating the precursor layer to allow the material of the metal matrix to diffuse into the particles of the first metal material, wherein... In the precursor layer formation step, a second metal material, which serves as the metal matrix, is simultaneously plated with the first metal material, so that the particles of the first metal material are dispersed in the second metal material. After the formation of the precursor layer and before the heating step, a third metal material stacking step is further performed, wherein the third metal material is a metal different from the first and second metal materials and is capable of diffusing into either the first or second metal materials by heating.

8. The method for manufacturing a sliding member as described in claim 7, wherein, The third metallic material is softer than the first metallic material.

9. A method for manufacturing a hard object, The hard material in this manufacturing method comprises a first metal material and a second metal material, wherein the second metal material is softer than the first metal material, and the concentration of the second metal material has a gradient, which gradually increases from the center of the hard material towards the surface. Prepare the particles of the first metallic material. This allows the particles of the first metal material to come into contact with the melt formed by melting the second metal material.

10. The manufacturing method as described in claim 9, wherein, The particles of the first metallic material are obtained by impregnating an inorganic porous body into a melt formed by melting the metallic material.

11. The manufacturing method as described in claim 9 or 10, wherein, The first metal material is Bi or In, and the second metal material is Cu.

12. A method for manufacturing a sliding component, The method for manufacturing the sliding member comprises a hard material obtained using the method for manufacturing a hard material according to claim 9 or claim 10, which includes: Steps for preparing the substrate layer The plating process involves depositing a metal matrix material onto the surface of the substrate layer. During the plating step, the hard material is entrained in the bubbling gas of the plating bath.

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