JP2017071838A - Article having a composite hard film, and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an article having a composite hard film having a network groove for forming a network of a groove having a groove width of a micron order homogeneously, densely and with good adhesion in a raw material surface by a convenient method in a substrate having a flat surface or a curved surface without using any processing apparatus, and a producing method of the article.SOLUTION: An article having a composite hard film according to the invention includes: a slide member; a hard chromium plating layer formed on said slide member and having a network groove; and a hard film formed over said hard chromium plating layer and formed with a groove that correspond to at least a portion of said network groove.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an article having a composite hard coating and a method for producing the same.

  As a protective film for sliding parts such as machine parts, tools, molds, etc. used in sliding environments, there is a need for a hard film coating that has long life, high reliability, durability, and can be used with peace of mind. Yes. As hard films, metal nitride, metal carbide, amorphous carbon film formed by dry coating method, hard chromium plating formed by wet plating method, nickel-phosphorus alloy plating, nickel-boron alloy plating, etc. are wear resistant. Used for improvement coating.

  However, the seizure or adhesion at the sliding portion cannot be prevented only by coating the sliding member with the hard film. Therefore, in addition to the hard film coating, the lubricating oil is also used in the sliding member.

  In recent years, difficult processing including high-strength materials has increased in production machines, and work efficiency and productivity have been strongly demanded, and the use environment of machine parts and molds has become increasingly severe. In order to meet these needs, development of wear-resistant coatings that exceed conventional hard coatings has been underway. On the other hand, in manufacturing sites, it is widely practiced to add an extreme pressure additive to lubricating oil to prevent seizure between the workpiece, tool / mold, and machine parts.

  Currently, with the growing awareness of the environment around the world, there is a strong demand for a shift to production methods that reduce environmentally hazardous substances as much as possible in the manufacturing process. For extreme pressure additives containing halogens, the amount of oil used must be reduced. The movement to reduce or reduce is accelerating.

  In order to reduce the amount of oil used, technical development has been promoted as a solution to intentionally impart an uneven shape such as a groove to the protective film to improve the retention of the lubricating oil and lubricant and improve the lubricity. An old example is porous chrome plating by electroplating. This is to improve the oil retaining property of the sliding surface by enlarging the micro cracks in the hard chrome plating by etching and impregnating oil into the groove formed thereby. Has been reported.

On the other hand, technology development for imparting a groove shape to a hard film by PVD or CVD has also been advanced. In Patent Document 2, a groove is formed by masking a base material to form a hard film. In Patent Document 3, a groove shape is made on a substrate with a laser or the like, and a hard film is formed thereon. In Patent Document 4, a shape is formed on a hard film by laser processing.
In Patent Document 5, copper plating is applied to the surface of a base material, copper plating is etched with a photosensitive solution or electronically depicted, an uneven shape is imparted to the surface, a hard film is formed thereon, and uneven hard Get a membrane.

  In Patent Documents 6 and 7, the wear resistance is improved by coating a hard film such as a nitride, carbide, or amorphous carbon film on the hard chromium plating. In Patent Document 8, when hard chromium plating is performed, a plating film having macro unevenness formed on the surface is obtained by repeating electrolytic deposition of the plating film and anodic etching of the plating film, and the hard film is formed thereon. Form.

JP 2006-219756 A International Publication No. 2011/030926 JP 2012-188698 A JP 2010-137540 A JP 2007-130996 A JP 2011-157609 A JP2013-174002A Special table 2011-516726 gazette

  As described above, in the shape imparting to the hard film by using the laser technology that has been studied so far, the substrate or the hard film itself is prepared by using a processing device such as a drawing device or a laser device. . However, this method has a problem that a high-energy and expensive laser processing apparatus for forming a minute pattern must be used. Further, in this technique, it is technically difficult to form fine grooves having a groove width of micrometer in a high-density network, and it takes a long time to form a pattern over a large area. Furthermore, in general sliding parts and molds, a plane and a curved surface are mixed in a complicated manner, and it is extremely difficult to form a concavo-convex pattern uniformly on a material, which requires high technology, time, and cost.

  In addition, the technology using a photosensitive solution requires a complicated process of patterning as exposure mask preparation, resin solution application, exposure, development, and etching. Moreover, it is difficult to form a uniform pattern and it is not practical.

  In the method using hard chrome plating, when dry coating is performed directly on the hard chrome plating, the adhesion of the hard film is poor, and there is a problem in that abnormal wear occurs due to fragments of the peeled film. The decrease in the adhesion of the hard film is due to the large amount of hydrogen generated during plating being taken into the chromium plating, and it is difficult to obtain sufficient adhesion simply by the hard film due to the oxide layer on the surface.

  In the technique of forming a recess by repeating electrolysis and etching at the time of producing the chromium plating, the plating formation and the etching are repeated to obtain various uneven shapes of several hundred μm level. However, oil retention is insufficient on a large uneven surface, and it is difficult to maintain wear resistance for a long period of time when used for a sliding member. Furthermore, when forming a concave-convex shape in which the concave portion is a mesh shape, the area of the convex portion that supports an external load when sliding is significantly smaller than the concave portion, so the load on the film is large and durability is a problem. .

  The present invention has been made in order to solve the above-described problems. For a substrate having a flat surface or a curved surface, a groove having a groove width on the surface of a micron order on a surface by a simple method without using a processing apparatus. It is an object of the present invention to provide an article having a composite hard film having a network-like groove to form a uniform network at a high density and with good adhesion on the surface of the material, and a method for producing the same.

  An article having a composite hard coating according to the present invention includes a sliding member, a hard chrome plating layer formed on the sliding member and having a knitted groove, and a hard film formed on the hard chrome plating layer. And the hard film | membrane in which the groove | channel corresponding to at least one part of the said mesh-shaped groove | channel is formed is provided.

  In the article having the composite hard coating, the groove formed in the hard film is a groove communicating with the groove formed on the surface of the hard chrome plating layer, and extends inside the hard chrome plating layer. It can also communicate with the groove.

  In each of the above articles, the thickness of the hard chromium plating layer can be 3 to 1000 μm, and the thickness of the hard film can be 0.1 to 30 μm.

  In each of the above articles, the width of at least a part of the groove of the hard film communicating with the groove of the hard chrome plating layer can be 0.1 μm or more.

  The method for producing a composite hard coating according to the present invention includes a step of forming a hard chrome plating layer on the surface of the sliding member, a step of expanding the cracks possessed by the hard chrome plating layer into a mesh-like groove by etching, Forming a hard film on the hard chrome plating layer having the mesh-like grooves by a dry coating method.

  The method for producing an article having a composite hard coating further includes a step of performing ion bombardment treatment with argon gas on the hard chromium plating layer having the stitch-shaped grooves prior to the step of the hard coating. Can do.

  In the manufacturing method of each article, the hard film may be TiN, TiC, TiCN, TiAlN, AlCrN, CrN, BN, or DLC.

  In the manufacturing method of said each article | item, after forming the said hard film, the process of grind | polishing the surface of the said hard film can further be provided.

  According to the present invention, even on a substrate having a flat surface or a curved surface, mesh-like and high-density fine grooves having a groove width on the order of micrometers can be imparted to the hard film without using a processing apparatus.

It is a partial top view of the article | item which has the composite hard film which concerns on one Embodiment of this invention. It is sectional drawing of FIG. It is a top view which shows an example of a hard chromium plating layer. The top view of the hard chromium plating layer (a) after performing chemical etching, and the hard chromium plating layer (b) after performing anode etching. FIG. 5A is an enlarged view of a part of FIG. 4A, and FIG. 5B is an enlarged view of a part of FIG. 4B. It is a perspective view which shows schematic structure of the composite hard film concerning this invention. It is a figure which shows the hard chrome plating layer after an etching. It is an enlarged view (a) of a groove before ion bombardment treatment, and an enlarged view (b) of a groove after ion bombardment treatment. It is a graph which shows the relationship between the time of an ion bombard process, and the average increase length of a groove width. 1 is a diagram showing a film according to Example 1. FIG. It is sectional drawing of FIG. It is an enlarged view of FIG. It is a figure which shows the result of having performed the X-ray-diffraction measurement with respect to the film concerning Example 2. FIG. It is a figure which shows the state which mirror-finished the film of Example 1. FIG. 6 is a view showing a film according to Example 2. FIG. It is a figure which shows the result of having performed the X-ray-diffraction measurement with respect to the film concerning Example 2. FIG. 6 is a view showing a coating film according to Example 3. FIG. It is a figure which shows the result of having measured the Raman spectrum with respect to the film concerning Example 3. FIG. It is a figure which shows the relationship between the film thickness of a hard film, and groove width. It is a figure which shows the result of the scratch test of the film concerning Example 1. FIG. It is a figure which shows the result of the scratch test of the film concerning Example 2. It is a figure which shows the result of the scratch test of the film concerning Example 3. It is a figure which shows the result of the scratch test of the film concerning Example 4. It is a figure which shows the result of the scratch test of the film concerning the comparative example 1. It is a figure which shows the result of the scratch test of the film concerning the comparative example 2. It is a figure which shows a pin-on-disk tester. It is a figure which shows the friction wear characteristic which concerns on Example 1 and Comparative Example 1. FIG. It is a figure which shows the friction wear characteristic which concerns on Example 1 and Comparative Example 1. FIG. It is a figure which shows a cylindrical deep drawing test machine. It is the external appearance photograph (a) of the cylinder for cylindrical deep drawing tests using Example 1, and the enlarged view (b)-(e) of R part. It is a figure which shows the result of the cylindrical deep drawing test 1 using Example 1 and the comparative example 1. FIG. It is a figure which shows the result of the cylindrical deep drawing test 2 using Example 1 and the comparative example 1. FIG. The

Hereinafter, the composite hard coating and the manufacturing method thereof according to the present invention will be described.
<1. Outline of Composite Hard Film with Groove Structure>
First, an embodiment of an article having a composite hard coating according to the present invention will be described with reference to the drawings. FIG. 1 is a partial plan view of a composite hard coating having a groove structure according to this embodiment, and FIG. 2 is a cross-sectional view of FIG. The composite hard coating according to the present invention is formed on the surface of a sliding member such as a machine part, tool, or mold used for the sliding portion. As shown in FIG. A network-like (mesh-like) groove is formed on the surface. That is, the surface of the composite hard coating is segmented by the grooves. And long-term sliding performance can be ensured by lubricating oil being hold | maintained at this groove | channel.

  As shown in FIG. 2, the composite hard coating includes a hard chrome plating layer having a knitted groove formed on the surface of the sliding member and a hard film formed on the hard chrome plating layer. . A knitted groove is formed in the lower hard chrome plating layer, and a groove corresponding to the groove of the hard chrome plating layer is formed in the upper hard film. That is, in this composite hard coating, a hard film is laminated on a groove of a hard chrome plating layer having a knitted groove so that a network-like groove similar to the hard chrome plating layer can be formed on the hard film. is there. Hereinafter, each material will be described.

<2. Sliding member>
Sliding members are mainly mechanical parts that slide with other members such as bearings, cylinders, and piston rods, and tools and molds used for processing that causes sliding. Carbon steel, low alloy In addition to steel-based materials such as steel, high alloy steel, various stainless steels, etc., it may be formed of materials such as Al and its alloys, Ti and its alloys, Mg alloys, Ni and their alloys, copper and their alloys, etc. preferable. These materials have a wide range of use as mechanical members and have good electrical conductivity with respect to the electroplating treatment for the hard chromium plating layer.

<3. Hard chrome plating layer with stitch-like groove structure>
First, the hard chrome plating layer formed on the surface of the sliding member is chrome plated by a known electroplating process. The thickness of the chromium plating layer can be set to 3 μm to 1000 μm, for example. As the plating solution, a known chromic acid plating solution using sulfuric acid as a catalyst, a chrome plating solution containing silicofluoric acid, a commercially available chrome plating solution using an organic sulfonic acid as a catalyst, a trivalent chromium plating solution, or the like should be used. Can do. The setting of the groove density of the composite hard coating includes the type of chromium plating solution, bath composition (chromium concentration 10 to 400 g / L and catalyst concentration 0.1 to 40 g / L) and plating conditions (current density 5 to 100 A / dm ² , Select and control bath temperature 20-70 ° C.

And in order to form a mesh-like groove structure in this hard chrome plating layer, the hard chrome plating layer obtained above is etched and the micro crack which exists in a chromium plating film is expanded. As a result, network-like grooves are formed on the surface of the hard chrome plating layer. Etching methods include dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid, solutions containing organic acids such as acetic acid (0.1-5 mol / L), acid solutions containing several percent of hydrogen peroxide, and hard Chemical etching by immersing a chrome-plated member, or anodic electrolysis of a member chrome-plated in an alkaline solution such as sodium hydroxide (1 g / L to 100 g / L) or a chromic acid solution (1 to 400 g / L) Etching, to achieve. The width of the groove formed by etching is controlled by solution concentration, temperature (10 to 70 ° C.), time (several tens of seconds to several tens of minutes), and anode current density (1 to 50 A / dm ² ). The width of at least a part of the grooves formed in this way can be formed in the range of 0.2 to 16 μm, preferably 0.5 to 14 μm, more preferably 1.0 to 12 μm, 3.0-10 micrometers is especially desirable. In addition, the crack of the hard chromium plating layer is formed not only on the surface but also on the inside. That is, many cracks are also three-dimensionally formed in the thickness direction of the hard chrome plating layer. And the crack formed in the surface of the hard chromium plating layer and the internal crack connected to the crack are expanded by etching, and become a groove.

  The minimum thickness of the hard chrome plating film is the crack density (several tens / cm) inherent in the hard chrome plating, the groove width (0.2 μm to 16 μm) enlarged by etching of the hard chrome plating, and the hard film coated thereon It is desirable to determine the thickness (0.1 to 30 μm). When the groove width formed by etching exceeds 16 μm, the grooves are close to each other, it is difficult to maintain the shape as a groove, and the flatness of the plating surface is lost. Furthermore, the hard chrome plating layer is easily removed from the substrate when the intended sliding component is used.

<4. Hard film>
Various materials such as a nitride, a carbide, and an amorphous carbon film can be applied to the hard film. Specifically, for example, TiN, TiC, TiCN, TiAlN, AlCrN, CrN, BN, or DLC can be used. The thickness of the hard film is preferably, for example, 0.1 to 30 μm, more preferably 0.3 to 25 μm, and particularly preferably 1 to 20 μm, but according to the width of the groove to be formed, It can be changed as appropriate. In addition, network-like grooves are formed in the hard film so as to correspond to the grooves of the hard chromium plating layer described above. And the width | variety of at least one part of this groove | channel can be formed in the range of 0.1-15 micrometers, However, It is preferable that it is 0.5-14 micrometers, It is more preferable that it is 1.0-12 micrometers, 3.0 10 μm is particularly desirable.

<5. Method for producing composite hard coating on sliding member>
Next, the manufacturing method of the coating for sliding members is demonstrated. First, a hard chromium plating layer is formed on the surface of the sliding member by electroplating. FIG. 3 is a plan view showing an example thereof. At this time, cracks inherent in the hard chromium plating layer are about 0.05 μm, and are difficult to visually recognize in the same drawing.

  Next, etching is performed on the hard chrome plating layer, cracks inherent in the hard chrome plating layer are spread, and grooves having a mesh structure are formed on the surface. For the etching, a chemical etching method or an anodic electrolytic etching method can be used.

  By performing an etching process on the hard chromium plating layer, a crack of about 0.05 μm in the hard chromium plating layer can be expanded into a groove shape having a width up to 16 μm. For example, FIG. 4A shows a hard chrome plating layer after chemical etching, and FIG. 4B shows a hard chrome plating layer after anodic etching. The groove width of the hard chrome plating layer after chemical etching is 6.6 μm, and the groove width of the hard chrome plating layer after anodic etching is 5.8 μm. As shown in these drawings, by performing etching, the groove shape is clear and the groove width can be increased compared to the cracks inherent in the chromium plating of FIG. At this time, not only the cracks opened on the surface of the hard chrome plating layer but also other cracks communicating with the bottom of the cracks are enlarged and become grooves.

  For the measurement of the groove width, an optical microscope or a scanning electron microscope is used to observe four locations including a plane portion, a curved surface portion, and an end portion of a test piece or a product at a magnification of 500 times and exist within the observation field. The width of the groove can be measured with reference to a scale bar provided in an optical microscope or a scanning electron microscope or a tool for determining an accurate scale at the observation magnification. In addition, when it is difficult to measure the groove width by observation at a magnification of 500 times, at a magnification of 1000 times, observe at least six locations including the test piece or the flat portion, curved surface portion, and the vicinity of the end of the product. Measure with this method. Furthermore, when the average groove width is 0.5 μm or less, which makes it difficult to measure the groove width by observation at a magnification of 1000 times, observation is performed at a magnification of 8000 times. In that case, 10 or more places including the plane part and end part vicinity of a test piece or a product are observed, and it measures by said method. Unless otherwise stated, the groove width described below is a value measured by this method.

  5A is an enlarged view of part of FIG. 4A, and FIG. 5B is an enlarged view of part of FIG. 4B. Chemical etching and anodic etching not only expand the outermost grooves, but also extend the grooves present in the hard chrome plating layer. According to these figures, it can be seen that a groove existing inside communicates with a groove on the surface.

  Next, a fine adjustment of the groove of the hard chromium plating layer and a treatment for improving adhesion are performed. As this treatment, an ion bombardment treatment with argon is performed. The ion bombardment treatment removes etching residues and burrs remaining on the hard chromium plating layer having a knitted groove, and further removes oxides on the surface of the plating layer, thereby improving the adhesion of the hard film. In addition, the ion bombardment process has the effect of adjusting the groove width by smoothing the edge of the groove formed in the etching process of hard chrome plating, and smoothing the flat part. It also plays a forming effect. The gas used for the ion bombardment is preferably argon, but a rare gas, nitrogen, or oxygen can also be used. This ion bobber treatment can be omitted if the use conditions of the parts are not severe.

  Next, a hard film is formed. The film forming method is dry coating, and a CVD method or a PVD method can be used. Examples of the CVD method include thermal CVD and plasma CVD, and examples of the PVD method include vacuum deposition, ion plating, sputtering, laser ablation, ion beam position, and ion implantation. Thus, as shown in FIG. 1, a network-like groove corresponding to the surface of the hard chrome plating layer is formed on the surface of the formed hard coating. At this time, the grooves corresponding to all of the grooves of the hard chrome plating layer are not formed in the hard film. However, as described above, the grooves of the hard chrome plating layer are enlarged by etching, so that the grooves are enlarged. Grooves corresponding to most of the grooves are formed on the surface of the hard film.

  For parts that require a mirror surface, the composite hard film having a network-like groove can be polished if necessary. An example is buffing. In this case, by controlling the buff polishing conditions, it is possible to finish the mirror surface without losing the network-like grooves.

<6. Features>
As described above, according to the method for manufacturing a composite hard coating according to the present invention, a composite hard film in which a network-like groove is formed on a sliding member such as a machine part, a tool, or a mold used in a sliding part. A film can be formed. This manufacturing method consists of forming a hard chrome plating layer by electroplating, etching, and forming a hard film. Even if it is a three-dimensional shape regardless of the shape of the sliding member, it is a composite having a network-like groove. A hard film can be easily formed. Usually, film formation of a hard film by dry coating on a hard chrome plating layer has low adhesion, but in the present invention, groove formation on the hard chrome plating layer and surface adjustment using ion bombarding are performed on the hard film. The formed hard film is separated into segments to achieve high adhesion.

  In the composite hard coating of the present invention, the underlying hard chromium plating groove is continuous at least at a part of the bottom of the network-like groove. As a result, the lubricant penetrates not only into the groove formed in the upper hard film but also into the groove formed in the underlying hard chrome plating, and the sliding performance of the composite hard film is maintained over a long period of time. be able to.

  Further, the groove formed in the hard film is formed so as to correspond to the groove of the hard chrome plating layer. However, as shown in FIG. Instead, the grooves communicating with the grooves on the surface exist three-dimensionally in the thickness direction of the hard chromium plating layer. That is, at the bottom of the groove that opens on the surface of the hard chrome plating layer, there are a large number of locations that communicate with the groove existing inside the groove. Therefore, the lubricating oil enters and is retained in such an internal groove via the groove on the surface of the hard film. Therefore, even if the lubricating oil retained in the fine mesh grooves of the hard film on the outermost surface temporarily decreases due to severe sliding, the lubricating oil retained in the grooves inside the underlying hard chrome plating does not slide. The effect of preventing oil shortage by self-diffusion into the groove on the surface through the communicating part due to the load during movement can be expected.

  Examples of the present invention will be described below. However, the present invention is not limited to the following examples.

<1. Example 1>
A composite hard coating according to the present invention was produced according to the following steps. First, alloy tool steel SKD11 tempered material is prepared as a sliding member, and a hard chromium plating layer is formed thereon. Specifically, the sliding member was subjected to pretreatment such as polishing, washing, and degreasing, and then a hard chromium plating layer having a plating thickness of about 50 μm was formed.

As the chromium plating solution, a common chromium plating solution using sulfuric acid as a catalyst was used. The liquid composition was 250 g / L chromic anhydride and 2.5 g / L sulfuric acid. The plating conditions were a liquid temperature of about 50 ° C. and a current density of 20 A / dm ² . In order to improve the adhesion between the hard chrome plating and the substrate, in the initial stage of electrolysis, after performing the adhesion improvement treatment for about 20 A / dm ² for several minutes using the product as an anode, the hard chrome plating layer using the product as a cathode Formed.

  Next, chemical etching was performed on the hard chromium plating layer to spread cracks inherent in the chromium plating, and a knitted groove was formed on the surface. The solution used for immersion was dilute sulfuric acid (about 1 mol / L), and immersion was performed at room temperature for 5 minutes. By this operation, as shown in FIG. 7, a knitted groove having a groove width of about 5.3 μm was formed on the entire surface of the hard chrome plating.

Next, ion bombardment with argon gas was performed to further widen the grooves on the hard chrome plating layer. The conditions for the ion bombardment treatment are as follows.
-Substrate bias voltage: -500V
・ Filament current: 5A
・ Pressure: 1.3Pa
・ Time: 10 minutes ・ Substrate rotation speed: 5 rpm

  FIG. 8A is an enlarged view of the groove before ion bombardment, and FIG. 8B is an enlarged view of the groove after ion bombardment. By performing the ion bombardment, the groove width before processing was 5.3 μm and the groove width after processing was increased to 6.0 μm. Thus, by ion bombardment, the surface of the chromium plating can be sputtered and cleaned, and the groove width can be slightly expanded.

  FIG. 9 is a graph showing the relationship between the ion bombardment time and the average increase in groove width. According to FIG. 9, the groove width becomes wider as the treatment time is increased up to about 10 minutes, but the groove width does not increase even if the treatment is performed for a longer time.

  By ion bombardment, a knitted groove having a groove width of about 6.0 μm was formed on the hard chromium plating layer.

Subsequently, as a hard film, a CrN film having a thickness of about 10 μm was formed by arc ion plating on the hard chromium plating layer having a knitted groove. The film forming conditions are as follows.
-Substrate bias voltage: -50V
・ Pressure: 3.3Pa
・ Arc current: 70A
・ Temperature: 400 ℃

  As a result, a composite hard film having network-like grooves shown in FIG. 10 was formed. The average width of the grooves on this coating was about 4.1 μm. FIG. 11 is a cross-sectional view of the formed composite hard coating. It can be seen that grooves are formed in the hard film so as to correspond to the grooves formed in the hard chrome plating layer. Further, the hard film also penetrated into the groove of the hard chrome plating layer, and the side wall and bottom of the groove were also covered. By this coating, the characteristics of the hard coating can be imparted up to the inside of the groove. FIG. 12 is an enlarged view of the groove portion of the formed composite hard coating. As shown by the arrows in the figure, at the bottom of the groove of the hard film, there are many places where the groove extending inside the hard chrome plating layer as the base remains in an open state (see FIG. 6). Therefore, the lubricating oil applied on the composite hard coating is not only held in the fine mesh grooves on the outermost surface, but also penetrates and is held in the grooves of the hard chrome plating layer. As shown in FIG. 5, this characteristic is established by expanding the groove width by etching a groove of a hard chrome plating layer having a three-dimensionally complicated network-like crack on the base. When the hardness of the CrN film, which is a hard film, was measured by a nanoindentation method with a load of 3 mN, the hardness of the composite hard film was 18.5 GPa, indicating the hardness of a general CrN film. .

Moreover, the X-ray-diffraction measurement was performed with respect to this film. The measurement conditions are as follows.
・ Characteristic X-ray: CuKα
・ Voltage: 40kV
・ Current: 150mA

  As a result, the graph shown in FIG. 13 was obtained. From the position of the diffraction peak in FIG. 13, this film can be determined as CrN.

  Next, the CrN film was buffed with a diamond paste having a particle size of 6 μm and 3 μm by using a tabletop rotary polishing machine, and mirror-finished. In FIG. 14, a surface after polishing was obtained.

  The smoothness of the flat part of the CrN film was improved by mirror-finishing with a buff. By appropriately controlling the polishing conditions, it is possible to leave clearly without embedding the network-like grooves formed on the surface of the composite hard coating.

<2. Example 2>
Next, a composite hard coating according to Example 2 was produced. The difference from Example 1 is the hard film formed on the hard chrome plating layer, and the others are the same as Example 1. In Example 2, as the hard film, TiN having a thickness of about 10.7 μm was formed by arc ion plating. The film forming conditions are as follows.
-Substrate bias voltage: -50V
・ Pressure: 2.6Pa
・ Arc current: 100A
・ Temperature: 400 ℃

  As a result, a film as shown in FIG. 15 was formed. The average width of the grooves on this film was 4.0 μm. Therefore, it can be seen that a sufficiently wide groove is formed even for the hard film made of TiN.

Moreover, the X-ray-diffraction measurement was performed with respect to this film. The measurement conditions are as follows.
・ Characteristic X-ray: CuKα
・ Voltage: 40kV
・ Current: 150mA

  As a result, the graph shown in FIG. 16 was obtained. From the diffraction peak position in FIG. 16, this film can be determined as TiN. In addition, when the hardness of the TiN film which is a hard film was measured by a nanoindentation method with a load of 3 mN, it was 28.7 GPa, indicating the hardness of a general TiN film.

<3. Example 3>
Next, a composite hard coating according to Example 3 was produced. The difference from Example 1 is the hard film formed on the hard chrome plating layer, and the others are the same as Example 1. In Example 3, a DLC film having a thickness of about 5.3 μm (DLC: 3.1 μm, Cr / C gradient intermediate layer 2.2 μm) was formed as a hard film by an unbalanced magnetron sputtering method. The film forming conditions are as follows.
-Substrate bias voltage: -50V
Ar gas flow rate: 200 sccm
・ Methane gas flow rate: 10sccm
・ Temperature: 200 ℃

  As a result, a film as shown in FIG. 17 was formed. The average width of the grooves on this film was 2.2 μm. Therefore, it can be seen that a sufficiently wide groove is formed even for the hard film made of DLC.

In addition, a Raman spectrum was measured for the coating film at an excitation wavelength of 532 nm. As a result, the graph shown in FIG. 18 was obtained. According to FIG. 18, the spectrum is constituted by D-band and the 1350 cm ^-1 vicinity of G band near 1550 cm ^-1, the film can be determined with the DLC. When the hardness of the DLC film, which is a hard film, was measured by a nanoindentation method with a load of 3 mN, it was 10.9 GPa, indicating the hardness of a general hydrogen-containing DLC film.

<4. Relationship between hard film thickness and groove width>
Next, the relationship between the thickness of the hard film and the groove width was examined. Under the same conditions as in Example 1, CrN films having different thicknesses were formed as hard films, and the widths of the grooves formed on the surface were measured. The results are as shown in FIG. According to FIG. 19, the groove width and the film thickness in the hard film are inversely related. That is, the greater the thickness of the hard film, the smaller the width of the groove formed on the surface. Here, the slope of the straight line fitting by the least square method is −0.298. By using this constant, if the initial groove width is known, it becomes possible to calculate the fine groove width when an arbitrary film thickness is formed. Therefore, the groove width can be controlled by controlling the film thickness. However, this constant can be applied to film formation by the arc ion plating method, and this constant changes if the film formation method changes.

<5. Scratch test>
The adhesion of the hard film in each of the above examples was evaluated by a scratch test. In addition, the influence of the base of the hard film was also examined. That is, in each of the above embodiments, a hard chrome plating layer having a groove width increased by etching is used as a base, and a hard film is formed on the hard chrome plating layer. It was found that it was in close contact with the hard chrome plating layer and was not easily peeled off. Consider the following. First, the following two were prepared as comparative examples, and Example 4 was further prepared.

(Comparative Example 1)
The difference from Example 1 is that a hard chromium plating layer is not provided, and the others are the same as Example. That is, a CrN film having a thickness of about 10 μm was directly formed on the alloy tool steel SKD11 tempered material, which is a sliding member.

(Comparative Example 2)
The difference from Example 1 is that the hard chrome plating layer was subjected to mirror surface processing without performing etching and ion bombardment, and the others were the same as Example. That is, on the alloy tool steel SKD11 tempered material, which is a sliding member, a hard chrome plating layer is formed in the same manner as in Example 1, and then mirror-finished by buffing, and then CrN having a thickness of about 10 μm. A film was formed.

Example 4
The difference from Example 1 is the etching method of hard chrome plating, and others are the same as Example. That is, in Example 1, chemical etching was performed, whereas in Example 4, anodic etching was performed, and then a CrN film having a thickness of about 10 μm was formed in the same manner as in Example 1. For anodic etching, a standard chrome plating solution of 250 g / L of chromic acid and 2.5 g / L of sulfuric acid was used. The anodic electrolysis conditions were room temperature, a current density of 20 A / dm ² , and an electrolysis time of 1 minute.

(Evaluation method)
A scratch test was performed based on ISO20502: 2005 (E). The conditions are as follows.
・ Initial load: 0.3N
・ End load: 100N
・ Scratch distance: 10mm
・ Indenter: Diamond (tip radius 0.2mm)

  The results are as follows. 20 to 25 show Examples 1 to 4 and Comparative Examples 1 and 2 in which a scratch test was performed, respectively. In Examples 1 to 4 shown in FIGS. 20 to 23, all show good adhesion performance. When Examples 1 and 4 are compared (FIGS. 20 and 23), chemical etching shows higher adhesion than anodic etching. As shown in FIG. 5, it is considered that chemical etching has rough irregularities formed on the surface of the hard chrome plating layer, and the anchor effect with the hard film is strengthened.

  Further, in Comparative Example 2 shown in FIG. 25, it can be seen that peeling occurs at a low load, and adhesion is low. This is presumably because the hard film is formed without increasing the groove width. On the other hand, in Examples 1 to 4, the hard film is divided by the network-like grooves, so that the fracture range is reduced, thereby improving the adhesion.

<6. Friction and wear characteristics test 1>
Next, in order to confirm the sliding performance under liquid lubrication by the network-like groove, a pin-on-disk test was performed using an apparatus as shown in FIG. 26 (Tribogear TYPE-35S manufactured by Shinto Kagaku Co., Ltd.). It was. Here, the test was conducted using the coating films according to Example 1 and Comparative Example 1. First, liquid paraffin was applied to the surfaces of the hard films of Example 1 and Comparative Example 1, and a pin-on-disk test was performed. The test conditions are as follows.
・ Load: 15kg
・ Friction circle radius: 5mm
・ Rotation speed: 100rpm
・ Friction material: SKH51 (φ3mm pin)
・ Lubricant: Liquid paraffin

  The results are as shown in the friction and wear characteristics shown in FIG. In Comparative Example 1 (without fine grooves), the coefficient of friction increased abruptly in the vicinity of 100 seconds immediately after the start, so the test was stopped at this point. This seems to be because, in Comparative Example 1, oil could not be retained on the surface of the hard film, and the friction coefficient suddenly increased due to oil shortage between the pins and seizure. . On the other hand, Example 1 (with fine grooves) stably maintained a low coefficient of friction throughout. In Example 1, it is considered that stable frictional behavior was exhibited without causing oil shortage due to the oil retaining effect of the network-like grooves.

<7. Friction and wear characteristic test 2>
The friction and wear characteristic test 1 was a test under liquid lubrication, but here, a test under fixed lubrication is performed. The test method is different only in using molybdenum disulfide powder as a lubricant. The results are as shown in the friction and wear characteristics shown in FIG. As shown in the figure, in Comparative Example 1 (without fine grooves), the friction coefficient increased from around 800 seconds, and thereafter a high friction coefficient was maintained. This is considered to be because, in Comparative Example 1, the powder on the sliding surface decreased as the test progressed, and the partial seizure began to occur from around 800 seconds, thereby increasing the friction coefficient. It is done. On the other hand, Example 1 (without fine grooves) maintained a low coefficient of friction throughout. This is presumably because the powder held in the network-like grooves continued to be supplied to the sliding surface, thereby exhibiting stable friction behavior.

<8. Mold performance test 1>
Next, the mold performance in plastic working was evaluated by a cylindrical deep drawing test. As a tester, an automatic universal deep drawing tester SAS-200D manufactured by JT Toshi Co., Ltd. was used. In the cylindrical deep drawing tester shown in FIG. 29, the coatings according to Example 1 and Comparative Example 1 are formed on the die and wrinkle presser made of alloy tool steel SKD11 tempered material, and austenitic stainless steel (SUS304-2B). The cylindrical deep drawing test was performed several times. The conditions for cylindrical deep drawing are as follows.
・ Mold: Punch φ40.0 × R8mm
Die φ42.5 × R8mm
Wrinkle presser φ40.5mm
・ Work material: SUS304-2B (1mm ^t )
・ Lubricant: Former oil MS70
(Kinematic viscosity 70mm ² / s [40 ° C])
・ Molding speed: 80mm / min
・ Wrinkle presser force: 5kN
However, the work material was lubricated for each test.

  FIG. 30 shows an external appearance photograph (a) of the cylindrical deep drawing test die using Example 1 and enlarged views (b) to (e) of the R portion. It can be seen that a mesh-like groove is also formed in the R portion of the die. This indicates that the present technology can form a network-like groove even on a curved surface.

  FIG. 31 shows changes in the maximum deep drawing load of Example 1 and Comparative Example 1. When the mold according to Comparative Example 1 was used, cracks occurred during molding from the first to the 10th test, and 20 tests were required until the molding was stabilized. On the other hand, the mold according to Example 1 was stably molded from start to finish. Moreover, about the maximum load, the metal mold | die of Example 1 has shown the low maximum load compared with the metal mold | die of the comparative example 1, and forms a microgroove when compared with the average maximum load of 30-40 tests. It was found that the maximum load was reduced by about 7%.

<9. Mold Performance Test 2>
Next, a mold performance test 2 was performed. The difference from the mold performance test 1 is that the lubricating oil was applied to the mold before the start of the test, and after the start of the test, the test was performed without any lubrication to the mold and the workpiece. The results are as shown in FIG. In the mold according to Comparative Example 1, the maximum load significantly increased in 4 tests, and molding was impossible due to cracking in 6 tests, and 5 articles could be molded. On the other hand, the mold according to Example 1 was stably molded while maintaining a low maximum load up to 20 tests, and thereafter the maximum load gradually increased, but due to the excellent oil retaining effect, 26 The product could be molded.

Claims (8)

A sliding member;
A hard chromium plating layer formed on the sliding member and having a knitted groove;
A hard film formed on the hard chrome plating layer, wherein a hard film having grooves corresponding to at least a part of the mesh-shaped grooves, and
An article having a composite hard coating. The groove formed in the hard film is
The article having a composite hard coating according to claim 1, wherein the article communicates with a groove formed on a surface of the hard chrome plating layer and also communicates with a groove extending inside the hard chrome plating layer. .   The article provided with the composite hard coating according to claim 1 or 2, wherein the hard chromium plating layer has a thickness of 3 to 1000 µm and the hard film has a thickness of 0.1 to 30 µm.   The article having a composite hard coating according to any one of claims 1 to 3, wherein a width of at least a part of the groove of the hard film communicating with the groove of the hard chromium plating layer is 0.1 µm or more. Forming a hard chromium plating layer on the surface of the sliding member;
Expanding the cracks possessed by the hard chrome plating layer into a mesh-like groove by etching;
Forming a hard film by a dry coating method on the hard chromium plating layer having the mesh-shaped grooves;
A method for producing an article having a composite hard coating. Prior to the hard film process,
The method for producing an article having a composite hard coating according to claim 5, further comprising a step of performing ion bombardment treatment with argon gas on the hard chromium plating layer having the stitch-like grooves.   The method for manufacturing an article having a composite hard coating according to claim 5 or 6, wherein the hard film is TiN, TiC, TiCN, TiAlN, AlCrN, CrN, BN, or DLC.   The method for producing an article having a composite hard coating according to claim 5, further comprising a step of polishing the surface of the hard film after forming the hard film.