Plating film, composite film, sliding part, manufacturing method of plating film, manufacturing method of composite film, and manufacturing method of sliding part

Abstract

To provide: a plated film capable of preventing a surface shape increasing the surface area of the plated film from being degraded by a load; a composite film; a sliding component; a method for manufacturing the plated film; a method for manufacturing the composite film; and a method for manufacturing the sliding component.SOLUTION: A plated film 13 provided on the surface of a material 11 to be plated includes: a film part 14 including nickel or nickel alloy; and insulator or semiconductor inorganic compound particles 15 positioned in the inside of the film part 14. The surface of the film part 14 includes a smooth part 14A following the surface of the material 11 to be plated and a depression part 14B having a shape following at least a part of the appearance of the inorganic compound particle 15.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a plating film containing nickel or a nickel alloy, a composite film including the plating film, a sliding part including the composite film, a method for manufacturing the plating film, a method for manufacturing the composite film, and a method for manufacturing the sliding part. [Background technology]

[0002] In the field of surface treatment technology, nickel or nickel alloy plating is used to improve wear resistance, corrosion resistance, etc. Increasing the surface area of ​​a plating film improves the adhesive strength when resin is bonded to the plating film, improves adhesion to coatings, increases the amount of catalyst and lubricant carried, and improves solderability during soldering. One example of a technique for increasing the surface area of ​​a plating film is to form micropores in a Ni-P (nickel-phosphorus) plating film by immersing the film in acid (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP-A-1-191789 Summary of the Invention [Problem to be solved by the invention]

[0004] On the other hand, the method of immersing a plating film in acid roughens the entire surface of the plating film, leaving tapered convex portions scattered across the surface. When a load is applied to a plating film produced by this method, the load is concentrated on the tapered convex portions scattered across the surface, damaging the uneven shape. As a result, resins, coatings, etc. applied to the surface of the plating film may peel off from the plating film. [Means for solving the problem]

[0005] The plating film for solving the above problem is a plating film provided on the surface of a material to be plated, and comprises a film portion containing nickel or a nickel alloy and inorganic compound particles of an insulator or semiconductor located inside the film portion, and the surface of the film portion comprises a smooth portion that conforms to the surface of the material to be plated and a recess having a shape that follows at least a portion of the outer shape of the inorganic compound particles.

[0006] According to the above configuration, the surface of the coating portion has recesses, which increases the surface area of ​​the coating portion compared to a surface of a coating portion without recesses. This enables improved adhesive strength when resin is bonded to the plating film, improved adhesion to the coating film, increased support of catalysts, lubricants, etc., and improved solderability during soldering. Furthermore, because the surface of the coating portion has smooth portions that conform to the surface of the material to be plated, the load applied to the surface of the coating portion is distributed over a larger area compared to, for example, a case in which the surface of the plating film is dotted with convex shapes that do not conform to the surface of the material to be plated. This prevents deterioration of the surface shape of the plating film.

[0007] In the above-mentioned plating film, it is preferable that the recesses have a depth of 1 μm or more relative to the smooth portion, and that in a cross section of the plating film including the thickness direction of the plating film, the number of the recesses is 1 to 100 per 100 μm in a one-dimensional direction along the surface of the film portion, and the sum of the opening widths of the recesses is 2 to 50 μm per 100 μm in the one-dimensional direction. Also, in the above-mentioned plating film, it is preferable that the area of ​​the recesses is 2 to 50% of the surface of the film portion. According to each of the above configurations, it is possible to increase the surface area of ​​the plating film by providing recesses while suitably suppressing deterioration of the surface shape of the plating film by ensuring a sufficient area of ​​the smooth portion on the surface of the film portion.

[0008] A composite film for solving the above problems includes any of the above plating films and a surface layer composed of a lubricant located on the surface of the plating film. According to the above configuration, by providing a surface layer composed of a lubricant on the surface of a plating film having a smooth portion and a recessed portion, it is possible to improve the sliding properties of the smooth portion. Furthermore, even if the lubricant on the smooth portion decreases due to sliding, the lubricant filled in the recessed portion is supplied, thereby maintaining the sliding performance of the plating film surface. Furthermore, the recessed portion on the plating film can increase the retention of the lubricant.

[0009] In the composite coating, the surface layer preferably contains a layer lattice structure as the lubricant. A lubricant containing a layer lattice structure is less likely to lose solid lubricant from the surface of the plating film during sliding than other solid lubricants, liquid lubricants, and semi-solid lubricants. Therefore, by including a layer lattice structure as the lubricant in the surface layer, sliding performance can be maintained even when a component provided with the composite coating slides against another component.

[0010] A sliding component for solving the above problems includes any one of the composite coatings described above, and the surface of the composite coating is a surface that comes into sliding contact with a sliding object. According to the above configuration, by providing a surface of the sliding component with a composite coating, the sliding performance of the sliding component can be improved by providing a surface layer made of a lubricant containing a layered lattice structure on a plating film having a coating portion that includes a smooth portion and a recessed portion.

[0011] A method for producing a plating film that solves the above-mentioned problems includes: a first step of forming a plating film on the surface of a material to be plated by electroless plating or electroplating using a plating solution in which a nickel component is dissolved and insulator or semiconductor inorganic compound particles are dispersed, and depositing a film portion containing nickel or a nickel alloy derived from the nickel component on the surface of the material to be plated, thereby forming a plating film in which the inorganic compound particles are co-deposited inside and on the surface of the film portion; and a second step of contacting the plating film with a solution in which the inorganic compound particles are soluble but the film portion is insoluble, thereby dissolving the inorganic compound particles present on the surface of the plating film and forming recesses.

[0012] According to the above-described manufacturing method, in the first step, a plating film containing a coating portion and inorganic compound particles is formed on a plated material, and in the second step, the inorganic compound particles present on the surface of the plating film are dissolved. As a result, recesses having a shape that conforms to the outline of the inorganic compound particles are formed on the surface of the plating film at locations where the inorganic compound particles are present. This enables improved adhesive strength when resin is bonded to the plating film, improved adhesion to coatings, increased support of catalysts and solid lubricants, and improved solderability during soldering. Furthermore, smooth portions are formed on the surface of the plating film at locations where inorganic compound particles are not present. This allows the load applied to the surface of the coating portion to be distributed over a larger area than, for example, when protrusions that do not conform to the surface of the plated material are scattered on the surface of the plating film. Therefore, deterioration of the surface shape of the plating film can be suppressed.

[0013] A method for manufacturing a composite film to solve the above problem involves using the above-mentioned method for manufacturing a plating film to form the plating film on the surface of a material to be plated, and then forming a surface layer made of a lubricant on the surface of the plating film.

[0014] A method for manufacturing a sliding component for solving the above problems includes forming the composite coating on the surface of the sliding component using the above method for manufacturing a composite coating. [Effects of the Invention]

[0015] According to the present invention, it is possible to suppress deterioration due to load in a surface shape that increases the surface area of ​​a plating film. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a cross-sectional view of a sliding component. [Figure 2] FIG. 2 is a cross-sectional view of a plating film formed on a material to be plated in the first step of the method for producing a composite film. [Figure 3]FIG. 3 is a graph showing the relationship between the angle of the workpiece to be plated relative to the surface of the plating solution in the first step and the surface area ratio of inorganic compound particles on the surface of the plating film. [Figure 4] FIG. 4 is a cross-sectional view of a plating film from which inorganic compound particles exposed on the surface of the plating film have been removed in the second step of the method for producing a composite film. [Figure 5] 1 is an SEM image (secondary electron image) of the surface of the plating film in Example 1, from which inorganic compound particles exposed on the surface of the plating film have been removed. [Figure 6] 1 is a binarized image of an SEM image (backscattered electron image) of the surface of a plating film in Example 1 after the plating film is formed and before the inorganic compound particles are removed. [Figure 7] 1 is an SEM image (secondary electron image) of a cross section of a plating film in Example 1, from which inorganic compound particles exposed on the surface of the plating film have been removed. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, one embodiment of the present invention will be described with reference to FIGS. [Sliding parts] 1, the sliding element 10 is a component that constitutes, for example, an automobile engine or powertrain, etc. Specifically, the sliding element 10 is a component that constitutes various industrial products such as engine pistons and cylinders, bearings, shafts serving as sliding shafts, plunger pumps, washers, etc.

[0018] The sliding component 10 includes a plated material 11 having a flat, curved, or spherical smooth surface. The plated material 11 is, for example, a metal material such as steel, copper alloy, or aluminum alloy. Note that the plated material 11 is not limited to a metal material and may be a non-metal material such as glass or resin.

[0019] A composite coating 12 is provided on the surface of the plated material 11. The surface of the composite coating 12 is the surface that comes into sliding contact with any sliding object. The composite coating 12 includes a plating film 13 located on the surface of the plated material 11 and a surface layer 16 located on the surface of the plating film 13.

[0020] [Plating film] The plating film 13 is a layer formed, for example, by electroless plating or electroplating. The plating film 13 includes a coating portion 14 containing nickel or a nickel alloy and inorganic compound particles 15, which are particles having a different component from the coating portion 14. The plating solution used to form the plating film 13 contains a nickel component and the inorganic compound particles 15. The plating method for forming the plating film 13 is codeposition of the coating portion 14 and the inorganic compound particles 15. In the codeposition method for forming the plating film 13, the coating portion 14 derived from the nickel component is precipitated on the surface of the plated material 11, while the inorganic compound particles 15 are incorporated into the surface and interior of the coating portion 14. The plating thickness of the plating film 13 is, for example, 3 μm or more and 30 μm or less, but may be less than 3 μm or more than 30 μm.

[0021] The surface of the coating portion 14 includes a smooth portion 14A and a recessed portion 14B. The smooth portion 14A conforms to the surface of the material 11 to be plated. The smooth portion 14A is as smooth as the surface of the material 11 to be plated, or is smoother than the surface of the material 11 to be plated. The smooth portion 14A is one surface on the surface of the coating portion 14 that is not divided by the recesses 14B. The surface of the coating portion 14 has a sea-island structure in which the smooth portion 14A forms the sea and the recesses 14B form the islands.

[0022] The recesses 14B have a shape that follows at least a portion of the outer shape of the inorganic compound particle 15. For example, if the inorganic compound particle 15 is crystalline, the outer shape of the inorganic compound particle 15 has a crystal plane unique to the inorganic compound particle 15. If the outer shape of the inorganic compound particle 15 has a crystal plane, the surface that defines the recesses 14B includes a plane that reflects the crystal plane of the inorganic compound particle 15. If the inorganic compound particle 15 is an amorphous sphere, the outer shape of the inorganic compound particle 15 has a small spherical surface. If the outer shape of the inorganic compound particle 15 has a spherical surface, the surface that defines the recesses 14B has a spherical surface that reflects at least a portion of the spherical surface of the inorganic compound particle 15. If the inorganic compound particle 15 is a needle-shaped body with a tapered outer surface, the surface that defines the recesses 14B has a tapered shape that reflects at least a portion of the tapered outer surface of the inorganic compound particle 15.

[0023] The recesses 14B are formed by removing the inorganic compound particles 15 that have been co-deposited with the smooth portions 14A from the surface of the coating portion 14 during the formation of the plating film 13. A configuration in which the surface of the coating portion 14 has the recesses 14B increases the surface area of ​​the coating portion 14 compared to a configuration in which the surface of the coating portion 14 does not have the recesses 14B. Furthermore, because the smooth portions 14A bear the load applied to the coating portion 14, the load can be distributed over a larger area compared to a configuration in which the surface of the coating portion 14 has a tapered convex shape, and therefore deterioration of the surface shape of the plating film 13 is suppressed.

[0024] The inorganic compound particles 15 have low solubility within the pH range of the plating solution and do not interfere with the formation of the plating film 13 even when dissolved in the plating solution. The inorganic compound particles 15 are non-conductive insulator or semiconductor particles that are not charged and do not contribute to the deposition of the film portion 14 during the formation of the plating film 13. In this embodiment, a weakly acidic plating solution with a pH range of approximately 4.0 to 6.0 is used. The inorganic compound particles 15 are soluble in acidic or alkaline solutions in which the film portion 14 is insoluble. Examples of inorganic compounds that constitute the inorganic compound particles 15 include metal salts, metal hydroxides, and silicon oxides. An example of a metal that constitutes a metal salt or metal hydroxide is any one selected from the group consisting of calcium, magnesium, strontium, manganese, and titanium. Examples of metal acid salts include phosphates, oxalates, and carbonates. Specifically, the material constituting the inorganic compound particles 15 is at least one selected from the group consisting of manganese phosphate, calcium phosphate, strontium phosphate, titanium phosphate, nickel hydroxide, nickel oxalate, and magnesium carbonate.

[0025] The particle size of the inorganic compound particles 15 is preferably 20% to 200% in terms of 50% particle size (median diameter D50) of the required thickness of the plating film 13. By using inorganic compound particles 15 having a particle size within this range, the inorganic compound particles 15 can be suitably incorporated during deposition of the film portion 14, and the amount of inorganic compound particles 15 that are buried in the film portion 14 and not exposed on the surface of the film portion 14 can be reduced.

[0026] Furthermore, the Mohs hardness of the inorganic compound particles 15 is preferably similar to that of pure nickel and nickel alloys, for example, higher than that of pure nickel and lower than that of nickel alloys. For example, the Mohs hardness of pure nickel is approximately 3.5, the Mohs hardness of a nickel-phosphorus alloy, which is an example of a nickel alloy, is approximately 6, and manganese phosphate, which is an example of the inorganic compound particles 15, is approximately 5 (typical value). By using a substance having a Mohs hardness similar to that of pure nickel and nickel alloys as the inorganic compound particles 15, it is possible to suppress increases or decreases in the Mohs hardness of the plating film 13 due to the codeposition of the inorganic compound particles 15. Note that a substance having a Mohs hardness higher than that of pure nickel and nickel alloys may also be used as the inorganic compound particles 15.

[0027] [Surface layer] The surface layer 16 is present on the smooth portion 14A of the coating portion 14 and also fills the recesses 14B. The surface layer 16 is, for example, composed of a lubricant. The lubricant constituting the surface layer 16 may be a liquid lubricant (e.g., lubricating oil), a semi-solid lubricant (e.g., grease), or a solid lubricant. Examples of solid lubricants include inorganic compounds such as metal oxides, metal hydroxides, metal sulfides, and phosphate compounds, soft metals such as tin and lead, and resins such as PTFE. Even if the amount of lubricant on the smooth portion 14A of the surface layer 16 decreases due to sliding, the lubricant filled in the recesses 14B is replenished, thereby maintaining the sliding performance of the sliding component 10.

[0028] When the composite coating 12 is used in the sliding component 10 as in this embodiment, a solid lubricant containing a layer lattice structure is preferably used as the surface layer 16. The layer lattice structure improves sliding performance by cleaving the layer lattice. The layer lattice structure is an example of a solid lubricant, such as molybdenum disulfide, tungsten disulfide, graphite, boron nitride, or mica. The layer lattice structure maintains sliding performance by deforming and remaining on the smooth portion 14A when the sliding component 10 slides against another component. In other words, compared to other solid lubricants, liquid lubricants, and semi-solid lubricants, solid lubricants containing a layer lattice structure are less likely to be lost from the surface of the plating film 13 when the sliding component 10 slides against another component. Furthermore, even if the solid lubricant containing a layer lattice structure peels off from the surface of the plating film 13, it adheres to the surface of the sliding component, thereby maintaining sliding performance.

[0029] [Operation of the embodiment] A method for producing the composite coating 12 will now be described with reference to FIGS. [1st step] As shown in FIG. 2 , the manufacturing method of the composite coating 12 begins with a first step of forming a plating coating 13 on the workpiece 11 by electroless plating or electroplating. In the first step, a coating 14 derived from the nickel component contained in the plating solution is deposited on the surface of the workpiece 11, and inorganic compound particles 15 are incorporated into the surface and interior of the deposited coating 14 to form a co-deposited layer. Because the inorganic compound particles 15 are insulator or semiconductor particles, they are prevented from depositing around the inorganic compound particles 15 exposed on the surface of the plating coating 13. Therefore, the surface of the coating 14 other than the exposed inorganic compound particles 15 forms a smooth portion 14A conforming to the surface of the workpiece 11. The plating solution used in the electroless plating or electroplating in the first step will be described below.

[0030] [Electroless plating] The plating solution used in the electroless plating method contains inorganic compound particles 15, a nickel component, a reducing agent, a complexing agent, and a pH adjuster. The amount of inorganic compound particles 15 added is, for example, 0.1 g / L to 20 g / L, preferably 0.5 g / L to 10 g / L, and more preferably 1 g / L to 5 g / L. The inorganic compound particles 15 do not dissolve in the plating solution but are dispersed in the plating solution.

[0031] The nickel component is a water-soluble nickel compound that is soluble in the plating solution. The water-soluble nickel compound is, for example, at least one selected from the group consisting of nickel sulfate, nickel chloride, nickel sulfamate, and nickel hypophosphite. Nickel sulfate is particularly preferred because of its good solubility in the plating solution. The concentration of the nickel component is, for example, 0.5 g / L or more and 50 g / L or less.

[0032] The reducing agent is, for example, at least one selected from the group consisting of hypophosphorous acid, hypophosphites (sodium salts, potassium salts, and ammonium salts), dimethylamine borane, and hydrazine. The concentration of the reducing agent is, for example, 0.01 g / L or more and 100 g / L or less.

[0033] The complexing agent may be at least one selected from the group consisting of monocarboxylic acids, dicarboxylic acids, hydroxycarboxylic acids, aminopolycarboxylic acids, ethylenediaminediacetic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, and their ammonium salts, potassium salts, and sodium salts. Examples of the monocarboxylic acid include acetic acid and formic acid. Examples of the dicarboxylic acid include malonic acid, succinic acid, adipic acid, maleic acid, and fumaric acid. Examples of the hydroxycarboxylic acid include malic acid, lactic acid, glycolic acid, gluconic acid, and citric acid. Examples of the aminopolycarboxylic acid include ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid. Other complexing agents that may be used include phosphonic acids and amino acids. The concentration of the complexing agent is, for example, 5 g / L or more and 180 g / L or less.

[0034] The pH adjuster is at least one selected from the group consisting of inorganic acids such as sulfuric acid and phosphoric acid, sodium hydroxide, and aqueous ammonia. The pH range of the plating solution in the electroless plating method is usually 2 or more and 9 or less. In this embodiment, the pH range of the plating solution in the electroless plating method is 4.0 or more and 6.0 or less.

[0035] Various additives may also be added to the plating solution. Examples of additives include stabilizers, such as lead salts (e.g., lead nitrate and lead acetate), bismuth salts (e.g., bismuth nitrate and bismuth acetate), and sulfur compounds (e.g., thiodiglycolic acid and sodium thiosulfate). The amount of stabilizer added is, for example, 0.01 mg / L to 100 mg / L. Examples of additives include pH buffers, such as boric acid, phosphoric acid, phosphorous acid, carbonate, and their sodium, potassium, and ammonium salts. The amount of buffer added is, for example, 0.1 g / L to 200 g / L. Examples of additives include surfactants, such as nonionic, cationic, anionic, and amphoteric surfactants, which may be used alone or in combination. The amount of surfactant added is, for example, 0.1 mg / L to 100 mg / L.

[0036] The plating solution used in the electroless plating method of this embodiment contains 25 g / L of nickel sulfate hexahydrate, 25 g / L of sodium hypophosphite monohydrate, 20 g / L of malic acid, 10 g / L of sodium acetate, 10 g / L of sodium hydroxide, and 10 g / L of manganese phosphate. An optional stabilizer is also added to the plating solution so that the concentration of bismuth ions in the plating solution is 0.5 mg / L.

[0037] [Electroplating] In the case of electroplating, plating solutions such as a Watts bath and a nickel sulfamate bath are used. These plating solutions contain nickel components in addition to inorganic compound particles 15. The same numerical range as that for electroless plating can be applied to the amount of inorganic compound particles 15 added to electroplating. Note that the inorganic compound particles 15 do not dissolve in the plating solution but are present in a dispersed state in the plating solution.

[0038] In the case of a Watts bath, the nickel component is, for example, at least one selected from the group consisting of water-soluble nickel compounds such as nickel sulfate hexahydrate, nickel chloride hexahydrate, and nickel carbonate tetrahydrate. Among water-soluble nickel compounds, nickel sulfate hexahydrate or nickel chloride hexahydrate is preferred due to its excellent deposition on the workpiece 11, and a mixture of nickel sulfate hexahydrate and nickel chloride hexahydrate is more preferred. When a mixture of nickel sulfate hexahydrate and nickel chloride hexahydrate is used as the nickel component, it is preferred that the amount of nickel sulfate hexahydrate added be 200 g / L or more and 500 g / L or less, and the amount of nickel chloride hexahydrate added be 70 g / L or less. In the case of a nickel sulfamate bath, the nickel component is, for example, water-soluble nickel compounds such as nickel sulfamate or nickel chloride hexahydrate, or a mixture thereof.

[0039] The plating solution may also contain various primary and secondary brighteners. The primary brightener is at least one selected from the group consisting of saccharin, derivatives of benzene and naphthalene, such as sodium naphthalene sulfonate, sulfonates, and sulfonamides. The secondary brightener is at least one selected from the group consisting of butynediol, propargyl alcohol, and coumarin.

[0040] In this embodiment, the plating solution for the Watts bath contains 240 g / L of nickel sulfate hexahydrate, 45 g / L of nickel chloride hexahydrate, 45 g / L of boric acid, and 5 g / L of nickel oxalate dihydrate particles. Brighteners may also be included, including 2 g / L or less of saccharin and 0.2 g / L or less of butynediol. The pH range of the plating solution is 4.0 to 4.5.

[0041] The nickel sulfamate plating solution in this embodiment contains 450 g / L of nickel sulfamate tetrahydrate, 15 g / L of nickel chloride hexahydrate, 30 g / L of boric acid, and 5 g / L of nickel oxalate dihydrate particles, and has a pH range of 4.0 to 4.5.

[0042] [Method for controlling the amount of co-deposition of inorganic compound particles] Here, a method for controlling the amount of inorganic compound particles 15 co-deposited into the plating film 13 in the first step will be described with reference to Fig. 3. The horizontal axis of graph 100 shown in Fig. 3 represents the angle of the material 11 to be plated relative to the surface of the plating solution. The angle on the horizontal axis is 0 degrees when the surface of the plating solution is parallel to the material 11 to be plated, and 90 degrees when the surface of the plating solution is perpendicular to the material 11 to be plated. The vertical axis of graph 100 represents the surface area ratio of the inorganic compound particles 15 on the surface of the plating film 13 formed in the first step, i.e., before the inorganic compound particles 15 exposed on the surface are removed.

[0043] Curve 101 in graph 100 shows the surface area ratio of inorganic compound particles 15 in plating film 13 formed by electroless plating. Curve 102 in graph 100 shows the surface area ratio of inorganic compound particles 15 in plating film 13 formed by electroplating. The concentration of inorganic compound particles 15 in the plating solution is 2.0 g / L in both curves 101 and 102.

[0044] As shown in graph 100, the surface area ratio of the inorganic compound particles 15 on the surface of the plating film 13 decreased as the angle of the workpiece 11 relative to the surface of the plating solution increased in both the electroless plating method and the electroplating method. Therefore, by controlling the angle of the workpiece 11 relative to the surface of the plating solution, the surface area ratio of the inorganic compound particles 15 on the surface of the plating film 13, i.e., the co-deposition amount of the inorganic compound particles 15 in the plating film 13, can be controlled.

[0045] Specifically, the angle of the workpiece 11 relative to the surface of the plating solution may be from 0 to 90 degrees, and more preferably from 15 to 80 degrees. By setting the angle of the workpiece 11 relative to the surface of the plating solution within the above range, the inorganic compound particles 15 can be suitably codeposited in the plating film 13. However, if the angle of the workpiece 11 relative to the surface of the plating solution exceeds 90 degrees, the inorganic compound particles 15 may not be codeposited in the plating film 13.

[0046] [Second process] 4, a second step is performed in which the plating film 13 formed on the plated material 11 in the first step is brought into contact with a treatment liquid in which the inorganic compound particles 15 are soluble but the film portion 14 is insoluble. As a result, the inorganic compound particles 15 exposed on the surface of the plating film 13 are dissolved, and recesses 14B having a shape following at least a part of the outer shape of the inorganic compound particles 15 are formed.

[0047] The treatment liquid used in the second step is a solution containing an acid component, either an organic acid or an inorganic acid. The acid component contained in the treatment liquid is preferably an inorganic acid such as hydrochloric acid, sulfuric acid, nitric acid, or chromic acid, from the viewpoints of preventing corrosion of the coating portion 14 and quickly dissolving the inorganic compound particles 15. The pH range of the treatment liquid is 2.0 or less, preferably 1.0 or less. The plating film 13 can be brought into contact with the treatment liquid by immersion or spraying. In this embodiment, the immersion method is used. The concentration of the acid component in the treatment liquid is, for example, 0.1% by mass or more and 10% by mass or less. The treatment conditions in the second step are, for example, a contact time of 30 seconds or more and 600 seconds or less and a temperature of 10°C or more and 80°C or less.

[0048] The shape of the recesses 14B depends on the extent to which the inorganic compound particles 15 are exposed from the coating portion 14 on the surface of the plating coating 13. That is, the recesses 14B have various shapes, such as recesses whose openings are narrower than the interior, recesses whose openings are the same size as the interior, or recesses whose openings are wider than the interior. In particular, in this embodiment, recesses 14B whose openings are narrower than the interior can be formed, which allows the material that constitutes the surface layer 16 to be favorably supported.

[0049] The area ratio of recesses 14B to the surface of coating portion 14 is preferably 2% to 50%, and more preferably 5% to 40%. When the area ratio of recesses 14B to the surface of coating portion 14 is within the above range, the surface area of ​​coating portion 14 can be increased by recesses 14B while ensuring a sufficient area for smooth portion 14A.

[0050] In a cross section of the plating film 13, including the thickness direction of the plating film 13, the number of recesses 14B having a depth of 1 μm or more relative to the smooth portions 14A is preferably 1 to 100 per 100 μm in a one-dimensional direction along the surface of the coating portion 14. Furthermore, a number of recesses 14B having a depth of 1 μm or more relative to the smooth portions 14A is more preferably 2 to 50 per 100 μm. Furthermore, in a cross section of the plating film 13, the sum of the opening widths of the recesses 14B having a depth of 1 μm or more relative to the smooth portions 14A is preferably 2 to 50 μm, more preferably 5 to 40 μm, per 100 μm in a one-dimensional direction along the surface of the coating portion 14. By ensuring that the number and sum of the opening widths of the recesses 14B per 100 μm in a one-dimensional direction along the surface of the coating portion 14 are within the above ranges, the surface area of ​​the coating portion 14 can be increased by the recesses 14B while ensuring a sufficient area for the smooth portions 14A.

[0051] [3rd step] Finally, a third step is performed to form a surface layer 16 on the plating film 13 in which the recesses 14B were formed in the second step. In this embodiment, the surface layer 16 is formed on the plating film 13. Specifically, a dispersion in which particles of the layer lattice structure are dispersed in a solvent such as water or an organic solvent is applied to the surface of the plating film 13 by brushing, dipping, spraying, or other methods. The solvent is then evaporated by heating to form the surface layer 16. The dispersion may contain a binder such as a resin in addition to the particles of the layer lattice structure. Alternatively, the particles of the layer lattice structure themselves may be directly applied to the surface of the plating film 13 by brushing, dipping, spraying, or other methods. This results in a composite film 12 comprising the plating film 13 and the surface layer 16 being formed on the surface of the plated material 11.

[0052] [Effects of the embodiment] According to the above embodiment, the following effects can be obtained. (1) Because the surface of the coating portion 14 has the recesses 14B, the surface area of ​​the coating portion 14 is increased compared to a configuration in which the surface of the coating portion 14 does not have the recesses 14B. This improves the retention of the lubricant that constitutes the surface layer 16 and increases the amount of lubricant carried. Furthermore, compared to a configuration in which the surface of the coating portion 14 has a tapered convex shape, the smooth portions 14A, which have a larger area, can distribute the load applied to the coating portion 14. This can suppress deterioration of the surface shape of the plating layer 13. Therefore, the effects of the recesses 14B can be maintained in an optimal manner.

[0053] (2) By controlling the surface area ratio of the recesses 14B, the number of recesses 14B in the cross section, and the sum of the opening widths, the surface area of ​​the plating film 13 can be increased by the recesses 14B while ensuring a sufficient area for the smooth portions 14A and suitably suppressing deterioration of the surface shape of the plating film 13.

[0054] (3) Providing surface layer 16 made of a lubricant on the surface of plating film 13 improves the sliding performance of sliding component 10. Even if the amount of lubricant on smooth portion 14A decreases due to sliding, the lubricant filled in recessed portion 14B is supplied to smooth portion 14A, so the sliding performance of sliding component 10 is maintained.

[0055] (4) By using a solid lubricant containing a layered lattice structure as the surface layer 16, the layered lattice structure is less likely to be lost from the surface of the plating film 13 during sliding, and therefore the sliding performance of the sliding component 10 can be favorably maintained even when it slides against another component.

[0056] (5) In the first step, a plating film 13 including a film portion 14 and inorganic compound particles 15 is formed on the plated material 11, and in the second step, the inorganic compound particles 15 exposed on the surface of the plating film 13 are dissolved. As a result, recesses 14B having a shape that follows the outline of the inorganic compound particles 15 can be formed in the areas of the surface of the plating film 13 where the inorganic compound particles 15 are exposed. Furthermore, smooth portions 14A, which are smooth surfaces, can be formed in areas of the surface of the plating film 13 where no inorganic compound particles are present.

[0057] The above embodiment can be modified as follows. The lubricant constituting the surface layer 16 is not limited to a solid lubricant containing a layered lattice structure, but may be other solid lubricants, liquid lubricants, or semi-solid lubricants. In this case, the effect of (3) above can also be obtained.

[0058] The composite coating 12 can also be used for purposes other than the sliding component 10. Therefore, as long as the surface layer 16 is provided on the plating coating 13, the material of the surface layer 16 is not limited to a lubricant, and any material may be used, such as a molded resin, various coatings, a catalyst, or solder. In this case, it is possible to achieve improved adhesive strength due to the anchor effect when the resin is bonded to the plating coating 13, improved adhesion between the plating coating 13 and the coating, an increased catalyst loading, and improved solderability due to improved wettability during soldering.

[0059] As long as the area of ​​the smooth portion 14A can be sufficiently secured and the recesses 14B can increase the surface area of ​​the plating film 13, the area ratio of the recesses 14B on the surface of the film portion 14 is not limited to 2% or more and 50% or less, and may be, for example, more than 50%. Similarly, in the cross section of the plating film 13, the number of recesses 14B may be more than 100 per 100 μm in one-dimensional direction along the surface of the film portion 14, and the sum of the opening widths of the recesses 14B may be more than 50 μm per 100 μm.

[0060] Various types of plating films may be provided as a base between the plated material 11 and the plated film 13. For example, if a plating film that is sufficiently thick relative to the particle diameter of the inorganic compound particles 15 is required, a plating solution that does not contain inorganic compound particles 15 may be used to provide a plating film of the same type as the film portion 14 that does not contain inorganic compound particles 15 between the plated material 11 and the plated film 13. In this case, the plating film that does not contain inorganic compound particles 15 provided between the plated material 11 and the plated film 13 can prevent the recesses 14B from reaching the plated material 11. Note that the plating film provided between the plated material 11 and the plated film 13 does not have to be a plating film of the same type as the film portion 14.

[0061] [Example] Hereinafter, examples 1 to 8 of the present invention and comparative examples 1 to 6 will be described. Note that the above-described embodiments are not limited to the examples and comparative examples.

[0062] [Base material and plating pretreatment] In Examples 1 to 8 and Comparative Examples 1 to 6, a cold-rolled steel plate SPCC-SB (manufactured by Paltec Co., Ltd.) measuring 50 mm × 50 mm × 3.0 mm in thickness was used as the substrate. In addition, prior to the plating treatment, the surface of the substrate was cleaned in the following order: alkaline degreasing, deionized water washing, electrolytic degreasing, deionized water washing, acid washing (17% hydrochloric acid), and deionized water washing.

[0063] [Example 1] The substrate was immersed in the electroless plating solution while stirring with a stirrer, and electroless plating was performed at 90°C until the film thickness was approximately 5 μm. The plating solution used was a medium-high phosphorus electroless nickel plating solution "SE-666" (manufactured by Nippon Kanigen Co., Ltd.) to which 2 g / L of manganese phosphate particles "PL-55A" (manufactured by Nippon Parkerizing Co., Ltd.) was added. The substrate was then immersed in 15% hydrochloric acid at room temperature for 30 seconds to dissolve and remove the manganese phosphate particles that had co-deposited on the surface of the plating film, followed by rinsing with water and drying.

[0064] [Example 2] Electroless plating was carried out in the same manner as in Example 1, except that 0.5 g / L of titanium phosphate particles (manufactured by Fujimi Incorporated) was added instead of the manganese phosphate particles. Thereafter, the titanium phosphate particles co-deposited on the surface of the plating film were dissolved and removed in the same manner as in Example 1, followed by rinsing with water and drying.

[0065] [Example 3] Electroless plating was carried out in the same manner as in Example 1, except that 4 g / L of nickel hydroxide particles (manufactured by Junsei Chemical Co., Ltd.) was added instead of the manganese phosphate particles. Thereafter, the nickel hydroxide co-deposited on the surface of the plating film was dissolved and removed in the same manner as in Example 1, followed by rinsing with water and drying.

[0066] [Example 4] 5 g / L of nickel oxalate dihydrate particles (manufactured by Yoneyama Pharmaceutical Co., Ltd.) was added to the Watts bath, and the substrate was immersed in the bath while stirring with a stirrer. The current density was 2 A / dm at 50°C. 2 The plated specimens were electroplated using DC electrolysis at 1000 kJ / s to a thickness of approximately 5 μm. The Watts bath contained 280 g / L of nickel sulfate, 40 g / L of nickel chloride, and 20 g / L of boric acid, with a pH of 4.5. The specimens were then immersed in 5% chromic anhydride heated to 70°C for 600 seconds to dissolve and remove the nickel oxalate particles that had co-deposited on the plated surface. The specimens were then rinsed with water and dried.

[0067] [Example 5] After forming a plating film using the same process as in Example 1, a lubricating paint containing molybdenum disulfide, Deflic Coat, HMB-2 (manufactured by Kawamura Laboratory), was applied to the plating film to a dry film thickness of 5 μm to form a solid lubricating film.

[0068] [Example 6] A plating film was formed by the same process as in Example 2, and then a solid lubricating film was formed on the plating film by the same process as in Example 5.

[0069] [Example 7] A plating film was formed by the same process as in Example 3, and then a solid lubricating film was formed on the plating film by the same process as in Example 5.

[0070] [Example 8] A plating film was formed by the same process as in Example 4, and then a solid lubricating film was formed on the plating film by the same process as in Example 5.

[0071] [Comparative Example 1] The substrate was immersed in a medium-high phosphorus electroless nickel plating solution "SE-666" (manufactured by Nippon Kanigen Co., Ltd.) and electrolessly plated at 90°C while stirring with a stirrer until the film thickness was approximately 5 μm, after which it was washed with water and dried.

[0072] Comparative Example 2 After forming a plating film using the same steps as in Comparative Example 1, the plated film was immersed in 30% nitric acid at room temperature for 1 minute to form microcracks on the surface of the plating film, followed by rinsing with water and drying.

[0073] Comparative Example 3 The substrate was immersed in a plating solution containing 220 g / L of nickel sulfate, 150 g / L of nickel chloride, and 20 g / L of boric acid while stirring with a stirrer, and the plating solution was heated at 50°C with a current density of 8 A / dm 2 The plate was electroplated using direct current electrolysis at 1000 kJ / s. The film thickness was approximately 1 μm. The plate was then washed with water and dried.

[0074] Comparative Example 4 A plating film was formed by the same process as in Comparative Example 1, and then a solid lubricating film was formed on the plating film by the same process as in Example 5.

[0075] Comparative Example 5 A plating film was formed by the same process as in Comparative Example 2, and then a solid lubricating film was formed on the plating film by the same process as in Example 5.

[0076] Comparative Example 6 A plating film was formed by the same process as in Comparative Example 3, and then a solid lubricating film was formed on the plating film by the same process as in Example 5.

[0077] [Method for evaluating recess area ratio] The area ratio of recesses on the surface of the plating film was measured by observing scanning electron microscope (SEM) images of the plating film for Examples 1 to 8 and Comparative Examples 1 to 6. As an example, a secondary electron image of the plating film 13 of Example 1 taken with an SEM is shown in FIG.

[0078] 5, the plating film 13 of Example 1 has a clear boundary between the smooth portion 14A and the recessed portion 14B, so that the area ratio of the recessed portion 14B can be determined by image analysis. In Example 1, the area ratio of the recessed portion 14B was 22%.

[0079] FIG. 6 is an SEM image (backscattered electron image) of Example 1 after the formation of the plating film 13. The manganese phosphate particles, which are inorganic compound particles 15 co-deposited on the surface of the plating film 13, were lightly polished with #3000 emery paper without being dissolved in hydrochloric acid. FIG. 6 is an image of the backscattered electron image acquired by SEM, binarized using Otsu's binarization method, an example of an image analysis method. In FIG. 6, the smooth portion 14A where the coating portion 14 composed of heavy elements is exposed appears bright, while the portion where the inorganic compound particles 15 composed of relatively light elements are buried appears dark. In this case, the dark portions of the inorganic compound particles 15 can be considered as the portions where the inorganic compound particles 15 are dissolved by the treatment solution to form the recesses 14B. This method allows for a simpler determination of the area ratio of the recesses 14B. Similar effects can be achieved by detecting elements specific to the inorganic compound particles 15 using EDS instead of a backscattered electron image.

[0080] [Method for evaluating the number of recesses and the width of the recess opening] For Examples 1 to 8 and Comparative Examples 1 to 6, copper was electroplated onto the plating film for the purpose of protecting the surface, and then the plating film was filled with resin. Then, a cross section of the plating film, including the thickness direction, was processed so that it could be observed, and SEM images of the cross section were observed to measure the number of recesses with a depth of 1 μm or more per unit length of 100 μm and the total opening width. As an example, FIG. 7 shows a secondary electron image obtained by observing the cross section of the plating film 13 of Example 1 with an SEM. Note that dashed line 200 in FIG. 7 is a line connecting the ridge lines of the smooth portion 14A. Furthermore, dashed line 201 in FIG. 7 is a line of the same shape as dashed line 200, but is a line shifted 1 μm in parallel from dashed line 200 toward the plated material 11.

[0081] 7, the plating film 13 of Example 1 has a copper plating layer 20 formed on its surface. In Example 1, the number of recesses 14B having a depth of 1 μm or more relative to the smooth portion 14A was 10 per 100 μm of unit length. The sum of the opening widths of the recesses having a depth of 1 μm or more was 23 μm per 100 μm of unit length.

[0082] [Paint adhesion evaluation method] For Examples 1 to 4 and Comparative Examples 1 to 3, a coating film with a dry thickness of 15 μm to 20 μm was formed by applying a spray paint (water-based multi-purpose black spray, manufactured by Asahipen Co., Ltd.) to the plating film. Then, a sharp cutter was used to create grid-shaped cuts extending from the coating film formed on the plating film, reaching the substrate surface. Specifically, 11 cuts extending in a first direction were created at 1 mm intervals, and 11 cuts extending in a second direction perpendicular to the first direction were created at 1 mm intervals. Each cut in the second direction was created so as to intersect with each cut in the first direction. Next, cellophane tape was attached to the coating film formed on the plating film, and the cellophane tape was then peeled off. The number of areas in which 50% or more of the coating film had peeled off was then counted among 100 areas defined by the grid-shaped cuts. Of the 100 areas defined by the cut marks, areas with 11 or more areas where 50% or more of the coating film had peeled off were rated as poor (×), areas with 1 to 10 areas where 50% or more of the coating film had peeled off were rated as fair (△), and areas with no areas where 50% or more of the coating film had peeled off were rated as good (◯).

[0083] [Sliding property evaluation method] For Examples 5 to 8 and Comparative Examples 4 to 6, the sliding properties were evaluated using a friction test by the ball-on-disk method. SUJ2C spherical test pieces with a diameter of 10 mm were used. The measurement conditions were a load of 19.6 N, a sliding circle diameter of 10 mm, and a rotation speed of 300 rpm. The evaluation method involved converting the friction force during rotation into a friction coefficient μ, and measuring the time until the friction coefficient μ exceeded 0.1. A time until the friction coefficient μ exceeded 0.1 of less than 2000 seconds was rated as poor (×), 2000 to 4000 seconds was rated as fair (△), 4000 to 6000 seconds was rated as good (◯), and 6000 seconds or more was rated as best (◎).

[0084] [Table 1]

[0085] As shown in Table 1, in Examples 1 to 8, the area ratio of the recesses 14B was 2% or more and 50% or less. Furthermore, in Examples 1 to 8, the number of recesses 14B per 100 μm in the cross section of the plating film 13 was 1 to 100, and the total opening width of the recesses 14B was 2 μm or more and 50 μm or less per 100 μm. In contrast, no recesses were observed in Comparative Examples 1 and 4. Furthermore, in Comparative Examples 2, 5, 3, and 6, recesses were observed over the entire surface of the plating film, and the area ratio of the recesses exceeded 50%. In Comparative Examples 3 and 6, the crystals of the nickel plating layer were strongly oriented in the (1.1.1) and (3.1.1) planes, resulting in the formation of a plating film with a severely uneven shape over the entire surface.

[0086] Furthermore, in the coating film adhesion evaluation, Examples 1 to 4 obtained better results than Comparative Examples 1 to 3. In Comparative Example 1, the absence of recesses is thought to have resulted in poor adhesion between the plating film and the coating film. In Comparative Example 2, the plating film itself was altered by the acid used to form the recesses, which is thought to have caused peeling between the plating film and the substrate. In Comparative Example 3, although the area of ​​the recesses was large, the plating film itself defining the recesses had a smooth surface, which is thought to have resulted in poor adhesion between the plating film and the coating film.

[0087] Furthermore, in the sliding property evaluation, Examples 5 to 8 obtained better results than Comparative Examples 4 to 6. In Comparative Example 4, the absence of recesses presumably led to poor adhesion between the plating film and the solid lubricating film, which is thought to have reduced the solid lubricating film as the sliding occurred. In Comparative Example 5, the plating film itself was altered by the acid used to form the recesses, which is thought to have caused peeling between the plating film and the substrate. In Comparative Example 6, the plating film itself defining the recesses had a smooth surface, which presumably prevented the plating film from maintaining a solid lubricating film, which is thought to have reduced the solid lubricating film as the sliding occurred. In addition to the above reasons, in Comparative Examples 5 and 6, the area of ​​the recesses was large and the area of ​​the smooth parts was small, which presumably damaged the uneven surface shape as the sliding occurred, making it impossible to support a solid lubricating film. [Explanation of symbols]

[0088] 10...Sliding parts 11...Material to be plated 12...Composite coating 13...Plating film 14...Coating part 14A…Smooth part 14B...recess 15...Inorganic compound particles 16…Surface layer

Claims

1. A plating film provided on the surface of a plated material, a coating portion containing nickel or a nickel alloy; inorganic compound particles of an insulator or a semiconductor located inside the coating portion, The surface of the coating portion is a smooth portion that conforms to the surface of the workpiece; a recessed portion where the inorganic compound particles exposed from the coating portion have been removed, The surface of the plating film does not contain the inorganic compound particles protruding from the smooth portion. Plating film.

2. the recess has a depth of 1 μm or more relative to the smooth portion, In a cross section of the plating film including a thickness direction of the plating film, the number of the recesses is 1 to 100 per 100 μm in a one-dimensional direction along the surface of the coating portion, The sum of the opening widths of the recesses is 2 μm or more and 50 μm or less per 100 μm in the one-dimensional direction. The plating film according to claim 1.

3. The area of ​​the recesses is 2% or more and 50% or less of the surface of the coating portion. The plating film according to claim 1 or 2.

4. The plating film according to any one of claims 1 to 3; a surface layer made of a lubricant located on the surface of the plating film; Composite coating.

5. The surface layer includes a layered lattice structure as the lubricant. The composite coating of claim 4.

6. A composite coating according to claim 4 or 5 is provided, The surface of the composite coating is the surface that comes into sliding contact with the sliding object. Sliding parts.

7. a first step of forming a plating film on the surface of the material to be plated, in which a plating solution in which a nickel component is dissolved and insulator or semiconductor inorganic compound particles are dispersed is used to deposit a film portion containing nickel or a nickel alloy derived from the nickel component on the surface of the material to be plated by electroless plating or electroplating, thereby forming a plating film in which the inorganic compound particles are co-deposited inside and on the surface of the film portion; a second step of bringing the plating film into contact with a solution in which the inorganic compound particles are soluble but the film portion is insoluble, thereby dissolving the inorganic compound particles present on the surface of the plating film and forming recesses. Manufacturing method of plating film.

8. After forming the plating film on the surface of a material to be plated using the method for producing a plating film according to claim 7, A surface layer made of a lubricant is formed on the surface of the plating film. Manufacturing method of composite coating.

9. The composite coating is formed on the surface of a sliding part by using the composite coating manufacturing method according to claim 8. Manufacturing method for sliding parts.

Images