JP4104570B2 - Manufacturing method of sliding member - Google Patents

Description

The present invention is made of a hard coating according EDM on the surface of the metallic material is formed to a method for producing a sliding member in which the surface properties such as friction and sliding performance was modified such wear resistance and seizure resistance.

  In recent years, the method of forming a hard coating on the surface of various members such as dies, dies, punches and drills by electric discharge machining has been widely used in combination with existing heat treatment. (Non-Patent Document 1). While applying these surface hardening treatments by electric discharge machining to the modification of sliding members to which high surface pressure is applied such as machine parts, the coating formed by electric discharge machining has high hardness, Since the surface has a fine concavo-convex shape, the sliding member provided with these coatings has problems such as attacking the mating member during sliding, causing the mating member to wear, and causing sag. It has been found to cause.

Further, according to Patent Document 1, the hard coating has a fine uneven surface left on its surface, and a sliding member having a hard coating with the fine uneven surface remaining is large if used as it is. Friction is caused and the sliding member is damaged. Moreover, since the said hard film is brittle and easy to peel, it is said that it is desirable to remove and use it at the same time as mirror finishing by lapping. Therefore, when applying electrical discharge machining to sliding members such as machine parts, it is essential to make fundamental improvements to the characteristics and form of the hard coating itself, and to reduce the aggression on the mating member. is there.
Mold technology 2003 Vol. 18, no. 12 JP 2000-301278 A

  As a method for improving the aggression against the mating member due to the surface unevenness of the electric discharge machining film, various methods using a mechanical or physical method such as a polishing process or a shot process using a hard ball are conceivable. By improving the surface roughness of the coating, the surface friction coefficient of the hard coating can be reduced. However, it has been found that in a sliding member in which the hard coating is in direct contact with the mating member, it is difficult to completely wipe off the aggressiveness against the mating member only by these general finishing processes.

Further, according to Japanese Patent Laid-Open No. 6-280044, additional secondary machining using electric discharge machining is performed, and at that time, a non-toxic gas is used on the machining surface, the generation of surface irregularities by the electric discharge film is weakened, and electric discharge machining treatment is performed. Improvements such as flattening, where the surface is less likely to be uneven, have been proposed. However, these reprocessing have concerns about cost reduction due to productivity reduction and reducing gas.
Accordingly, an object of the present invention is to provide a sliding member with improved attacking ability of the sliding member against the mating member when a hard film is formed on the surface of the metal material by electric discharge machining.

The above object is achieved by the present invention described below. That is, in the present invention, a hard film having a thickness of 5 to 30 μm is formed on the surface of a metal material by electric discharge machining in a hydrocarbon electric discharge machining liquid using a tungsten carbide consumable electrode, The outermost layer of the coating is polished to a surface roughness of 2 to 10 μm Ry, and the discharge coating area ratio after polishing of the surface is maintained at 30% to 70% . Further, the surface is subjected to phosphate treatment (hereinafter simply referred to as “chemical conversion treatment”). A method of manufacturing a sliding member, characterized in that the manufacturing method is performed.

In the present invention, it is preferable that the surface of the hard coating after the polishing is further subjected to a chemical conversion treatment , and the upper layer portion thereof is further subjected to a solid lubricating treatment.

  ADVANTAGE OF THE INVENTION According to this invention, the sliding member by which the aggressiveness with respect to the other party member was improved is provided by forming the hard film by electric discharge machining on the surface of a metal material, and modifying this film.

In order to solve the above problems, the inventors of the present invention have made the surface form of the electric discharge machining film as it is, the state of the surface layer after surface modification by shots, etc. Various analysis investigations with a scanning electron microscope were conducted on the form and the like. In the evaluation of the seizure performance of sliding members, various delicate analysis experiments on the frictional sliding interface, such as seizure resistance by various experiments using a frictional wear tester, the heat generation state of the friction surface, and changes in the friction coefficient, were conducted. , by effectively utilizing the hard film in the discharge machining, to relax the aggressiveness against the counterpart member is the biggest challenge has been developed a method of manufacturing a wear and seizure resistance excellent sliding member.

  The metal materials that are the objects of the sliding member of the present invention are mainly steel materials (including iron-based sintered alloys), titanium, aluminum, and the like, and these metal materials may be those that have been subjected to ground treatment in advance. Good. Examples of the base treatment of the steel material include surface hardening treatment such as carburizing quenching, induction quenching, soft nitriding treatment, quenching, tempering, etc. In the case of titanium and aluminum, for example, solid solution and Aging treatment or no treatment can be mentioned. The sliding member made of the metal material is a member used for a sliding portion in transportation equipment, industrial machinery, electricity, tools, daily necessities, etc., and slides with each other in a broad sense. It means a member, specifically a reciprocating sliding member or a rotational sliding member.

In the present invention, as a method for forming an electric discharge machining film on the surface of the metal material as described above, tungsten carbide is included as a hard film forming component as detailed in JP-A-2001-138141 and the like. The electrode composition is dissolved by using a consumable electrode of a powder pressure molded body and generating a pulse discharge between the surface of the metal material that is the material to be treated in the hydrocarbon-based electric discharge machining fluid, and the material to be treated A method is used in which a hard coating having a thickness of about 5 to 30 μm is formed on the surface of the metal material together with countless discharge trace coatings.

  When the outermost layer of the hard coating is analyzed, it is recognized that a hard ceramic coating produced mainly by electrical discharge machining of the electrode components tungsten, cobalt, etc. and the material to be treated is generated, and further in the deep part. Has a diffusion layer having a gradient composition formed by the reaction of the electrode main component and the member to be processed over a thickness of several μm. Next, the characteristics of the outermost layer of the coating were extremely hard and rugged, and analysis of the form of the discharge coating on which the projections and depressions were based revealed that the coating was a hard coating in which a number of sharp ridges overlapped. Therefore, when it is used as a sliding member in a state having such severe unevenness, it may be undesirable because it causes problems such as damaging the mating member or scooping the mating member.

  Next, according to Japanese Patent Application Laid-Open No. 11-320272, as a method for imparting lubricity to a hard coating formed by electric discharge machining, after forming a hard coating by electric discharge machining on a material to be treated, the surface of the hard coating is applied. There has been proposed a method for producing a coating which is polished and has holes on the surface. According to the above publication, the surface of the coating formed by electric discharge machining is in a scale-like state. For example, the hardness of the hard coating formed when a tungsten carbide electrode is used is equivalent to 1500 HV. The surface roughness is equivalent to about 5 μm Ry, and these hard coatings can be used for tools and molds, but it is said that they cannot be used for sliding members such as machine parts. On the other hand, since there are innumerable fine holes on the surface, a lubrication oil pool is created using these holes, and a method of polishing so that fine holes remain on the surface for the purpose of improving lubricity is proposed. Has been. As this effect, it is described that the amount of lubricating oil necessary for preventing seizure on the sliding surface of the machine part can be halved compared to the conventional case.

  In order to verify the above description, the present inventors investigated the relationship between surface roughness and seizure resistance in oil lubrication of the hard coating using a ring-on-disk friction and wear test. FIG. 1 shows the structure of the testing machine, the shape of the test piece, and the state of attachment to the apparatus. Here, the seizure resistance evaluation was performed using, as a rule, JIS-SCM420 machine structural steel as the rotating disk and gas carburizing and quenching to an effective hardening depth of about 0.7 mm. The ring to be fixed on the other side was carburized and polished.

Next, a tungsten carbide hard coating having a thickness of about 20 μm was formed on the sliding surface of the workpiece disk by submerged electric discharge machining. Using this, the following test pieces a to c were prepared.
-Test piece a: The surface roughness is 12 μm Ry and the surface is not polished while the electric discharge machining hard coating is formed.
-Specimen b: The coated surface is finished with a surface roughness of 6.5 μm Ry by shot and polishing.
-Test piece c: Three types of test pieces whose surface roughness is 1.5 μm Ry finished by shot and polishing the coating surface, and-Comparative test piece d: Carburizing quenching and polishing finish without electric discharge machining ( One kind of test piece having a surface roughness of about 1 to 2 μm Ry), and a total of four kinds of test pieces.

  Prior to the frictional wear test, the surface morphology of the test pieces a to c was analyzed with a scanning electron microscope, and the results are shown in FIG. 2 (scanning electron micrograph). Fig. 2a is a photograph of the surface of the test piece "a" with a hard coating. The surface morphology is extremely uneven, and numerous voids and microcracks are observed. Further, during electric discharge machining, the consumable electrode material composition melts. Slag produced by the reaction is also observed. FIG. 2b is a photograph of the surface of the test piece b. The surface of the coating surface after shot blasting is adjusted to a surface roughness of 6.5 μm Ry by polishing, and the surface slag is compared with the test piece a. A relatively flat surface from which is removed is observed. FIG. 2c is a photograph of the surface of the test piece c, which is a reproduction of a hole on the polished surface assuming Japanese Patent Laid-Open No. 11-320272. Is 1.5 μm Ry, and discharge coatings are observed in several places.

Table 1 shows the results of a frictional wear test in which the relationship between the surface roughness and the seizure resistance of each of the test pieces a to d was examined. From these results, the specimen a that has not been surface- polished has a slightly improved seizure load compared to the carburized and quenched specimen d, but the fluctuation of the friction coefficient and the heat generation at the interface are very large, and the attack on the mating member It turns out that there is a sex problem. Next, among the specimens b and c finished by polishing, the friction coefficient of the specimen b is relatively small, and the seizure load is about 1.5 times that of the carburized and quenched specimen d. Improved. On the other hand, in the case of the test piece c having a part of the discharge coating and having a surface roughness of 1.5 μm Ry finish, although the coefficient of friction is small, the seizure load is almost equivalent to the test piece d of only carburizing and quenching, It has been found that there is no superiority of the EDM film.

The measuring method of various physical properties in the above and the measuring method of various physical properties in the following description are as follows.
"Measurement method of surface roughness (stylus surface roughness measurement)"
It measured using the measuring device according to JIS B0601, and was displayed by the term according to JIS B0601, the definition, and the surface property parameter.
"Measurement method of seizure load"
It means the seizure load at the time when the torque generated by the friction between the test piece (ring) 4 and the test piece (disk) 5 of the friction and wear tester shown in FIG.
"Measurement method of seizure temperature"
The temperature at the time of seizure was measured with a thermocouple previously inserted in the vicinity of the sliding surface of the test piece (ring) 4 in FIG.
"Method of measuring friction coefficient"
The torque generated by the friction between the test piece (ring) 4 and the test piece (disk) 5 is measured with the torque meter 3 shown in FIG. 1 and applied to the friction coefficient calculation formula shown below determined by the test machine structure. The coefficient (μ) was determined.
Friction coefficient calculation formula: μ = FR / Wr
(In the above formula, μ is a friction coefficient, FR is a torque value, W is a pressurizing load, and r is an average radius of a test piece (ring).)

  That is, the test piece a is very aggressive against the mating member as it is, and the test piece c polished to a surface roughness equivalent to about 1 μm Ry, which is a general finishing accuracy of machining, is obtained by polishing. It was found that very unstable elements were intervening, such as the loss of the wear resistance characteristic inherent in the coating. Therefore, in applying electric discharge machining to improve the sliding member, it is essential to consider the form of the hard film by electric discharge machining, the surface roughness, the film thickness, and the interface reaction with the counterpart member.

  Therefore, in the case of applying a hard coating by electric discharge machining for the purpose of modifying the surface such as seizure resistance of the sliding member, the surface form of the hard coating is considered to have the most influence. The inventors studied various methods for controlling the form of unevenness present on the coating surface by electric discharge machining. As a result, the focus is on the shape and distribution state of the discharge coating, which is the origin of the EDM coating, and first, the ridge line corresponding to the edge of the discharge coating is flat and gently finished, and the optimal distribution of the discharge coating area ratio in the substrate In search of the form, and furthermore, a chemical conversion treatment film having lubricating properties was uniformly coated in advance on the surface irregularities of the hard film, and a self-lubricating and sliding member used for retaining lubricating oil during sliding and a method for producing the same were developed. .

  In the present invention, the “discharge coating” means a reaction product (hard film forming component) between a consumable electrode component and a material to be processed generated by pulse discharge in electric discharge machining. The “discharge coating area ratio” means the area ratio of the discharge coating to the total area of the sliding surface of the sliding member.

  Here, it is conceivable to apply a chemical conversion treatment or a solid lubricant directly to the hard coating surface to improve the lubricity, but the hard coating has a gradient composition by reaction with electrode components near the cloth as described above. However, the outermost surface portion is composed of a hard and brittle ceramic-based coating, and in the state where the hard coating is formed, the adhesiveness of the chemical conversion treatment film and the solid lubricating film is poor and application is difficult. Here, as a result of an experiment in which a steel material was used as the substrate to be treated, a tungsten-based electric discharge machining film was formed on the surface, and a phosphate-based chemical conversion treatment was directly applied to the surface, the outermost ceramic film and the chemical conversion film were formed. It was found that the interfacial reaction with the treatment liquid was slow, phosphate crystals were not uniformly formed, and skettle was generated throughout the chemical conversion coating. For this reason, it is necessary to remove the ceramic-based film as the uppermost layer of the electric discharge machining film by shot, grinding, chemical polishing, or electrolytic polishing to improve the iron-rich surface composition.

  Next, in order to maximize the adhesion to the hard coating and the oil retention / holding effect of the hard coating itself in the chemical conversion treatment process and the solid lubrication treatment process, various analyzes and investigations were conducted on the form and distribution of the discharge coating. As a result, the point of modifying the surface layer part of the hard coating by using shot or polishing is to leave as many discharge coatings as effective in wear resistance and to set the surface roughness within the optimum range. It turned out to be desirable.

  As an analysis method, a disk test piece made of JIS-SCR420 steel material was used. After carburizing and quenching with an effective hardening depth of about 1 mm, polishing was performed, and a discharge hard coating having a thickness of about 20 μm was formed on the tungsten-based electrode. . Next, to adjust the surface roughness of the coating, the ceramic coating on the top layer of the coating is peeled off by shot peening using crushed powder, and the surface roughness level is adjusted to 4 levels by polishing. Thus, test pieces A to D were prepared. The relationship between the surface roughness and the discharge coating area ratio was investigated, and the results shown in Table 2 were obtained.

From these results, it was found that both the surface roughness (μmRy) after shot finishing and polishing finishing of the outermost surface of the hard coating and the discharge coating area ratio are substantially correlated. Here, since the initial surface roughness of electric discharge machining is relatively large at about 15 μm Ry (test piece A), when the surface roughness is improved by surface finishing, the electric discharge coating that forms a hard coating when the electric discharge coating becomes thinner It was found that the area ratio also decreased (test pieces B to D). On the other hand, since seizure resistance is related to the surface roughness as shown in Table 1, it is recognized that the discharge coating area ratio is optimally 30% to 70% from the relationship between the two. As described above, by adjusting the surface roughness during finishing to an appropriate range, it is possible to adjust the distribution form of the discharge coating effective for wear resistance and seizure resistance to an optimum state.

From the above examination, the following became clear.
1. In order to improve the conflicting aggressiveness while maintaining the wear resistance which is the greatest feature of the hard coating by electric discharge machining, it is necessary to modify the hard coating and its surface form.
2. As a modification method, the outermost surface layer is adjusted to an optimum surface roughness by single or composite treatment such as blasting, polishing, chemical polishing, and electrolytic polishing.
3. The points at that time are to gently control the ridgeline and edges of the discharge coating, to control the discharge coating area ratio to 30% to 70% , and to manage the surface roughness to 2 to 10 μm Ry.
4). In addition, by applying a chemical conversion coating or a solid lubricant that has a lubricating property that can uniformly coat uneven surfaces such as ridgelines, gaps, and holes in the discharge coating in the next process, it can handle high surface pressure sliding. Can be provided.

Next, the present invention will be described more specifically with reference to examples.
[Example 1]
Using JIS-SCM420 structural steel, the disc (φ50 × 5t) and the ring (φ23 × 15t) for the frictional wear test piece described in detail above were manufactured and carburized under the condition of 930 ° C. × 5 hr. Diffusion treatment and oil quenching were performed under the conditions of ℃ × 2 hr, then tempering was performed under the conditions of 180 ℃ × 2 hours, and carburized ground treatment was performed with a surface hardness of 730 HV and an effective hardening depth of about 0.7 mm. It was. Next, an electric discharge machining film was formed on the sliding surface of the disk on the rotating side, and the ring to be fixed on the other side was carburized and polished to a surface roughness of 1 μm Ry.

In the electric discharge machining, a tungsten carbide-based consumable electrode was attached to the negative electrode, and this was performed in a hydrocarbon-based machining fluid to form a hard coating having a thickness of about 20 μm. Next, the surface of the hard coating was finished. Surface finishing is performed by a combination of shot processing and grinding processing using pulverized powder, and the surface roughness Ry is adjusted, and (A) 10 μm Ry, (B) 6 μm Ry, (C) 2 μm Ry and (D) 1 μm Ry 4 Specimen specimens were made. Incidentally, while the (E) EDM film for comparison (shot, no grinding), surface roughness 1 3 μmRy, (F) carburized and finish polishing process, also two test pieces of the surface roughness 1.5μmRy The seizure resistance was investigated using these test pieces.

  In addition, for the purpose of higher surface pressure, the test pieces B, D and E are subjected to a predetermined pretreatment after surface finishing, and a chemical conversion treatment using a manganese phosphate chemical conversion treatment agent is performed. The surface was uniformly coated with a film having a thickness of 3 μm. Further, the test piece C was subjected to a chemical conversion treatment with a manganese phosphate chemical conversion treatment agent, and then a molybdenum disulfide solid lubricant coating was applied to a thickness of about 10 μm and baked.

In the frictional wear test, the seizure load, the seizure temperature, the friction coefficient, and the like were evaluated using the above-described ring-on-disk frictional wear tester, and the results are shown in Table 3.

  The effect of the surface roughness of the EDM film on the seizure load is optimal when the surface roughness of the test pieces A, B and C is 2 to 10 μm Ry, and the effect is compared with that of the test piece F which is carburized and polished. In addition, an improvement in seizure resistance of about 1.4 to 1.5 times was confirmed. On the other hand, when the surface roughness is 13 μm Ry with the electric discharge machining of the test piece E, the seizure load is slightly higher than that of the test piece F, but the aggressiveness is stronger than the fluctuation of the friction coefficient, and the sag occurs early. There's a problem. In addition, when the surface roughness is less than 2 μm Ry in EDM and polishing finish of Specimen D, the hard coating becomes too thin and the test piece softens due to frictional heat and the seizure resistance becomes the same as Specimen F. did. From the series of results, it is recognized that the optimum surface roughness after surface finishing is 2 to 10 μm Ry.

  Next, combined with a chemical conversion treatment having lubricity, the test piece [B + Chemical conversion] with a surface roughness of 5 μm Ry has significantly improved seizure resistance, and its effect is about twice as high as that of the test piece F. Equivalent to. Furthermore, the test piece [C + chemical conversion + solid lubrication] combined with molybdenum disulfide coating has little improvement in seizure load itself, but has a very small coefficient of friction (μ) and is extremely effective for sliding members. . In addition, in the case of a test piece [D + Chemical conversion] that has been hardened with a surface roughness of 1 μm Ry and subjected to chemical conversion treatment, the initial friction coefficient decreases, but the seizure resistance performance is almost the same as that of the test piece F, and the improvement effect It is not allowed.

  In the chemical conversion treatment method that has been confirmed to have an effect on seizure resistance, the use of chemicals that match the surface roughness of the agent to be treated is better. If the surface roughness is fine, the thin film type coating is rough, and the surface roughness is rough. In this case, a thick film type chemical conversion coating is more desirable than uniformity, adhesion, lubricity and the like. Here, in addition to the phosphate coating, a sulfuration treatment, an oxide coating, and the like are also effective. In addition to molybdenum disulfide, solid or solid lubricants such as graphite and Teflon (registered trademark) are effective as solid lubricant coatings that are used in combination with phosphate coatings and are effective in reducing friction coefficient. It is also effective for reducing friction and improving seizure resistance without lubrication. The above-mentioned “sulfurization treatment” is a treatment for forming iron sulfide on the surface layer by electrolytic treatment of an iron-based member in a molten salt or aqueous solution containing a sulfur compound for the purpose of reducing the friction coefficient of the surface layer portion. The “oxide film treatment” is a treatment method for forming a layer of iron tetroxide by treating an iron-based member in an atmosphere such as high-temperature steam.

[Example 2]
Shift-hawk members that shift gears to drive system parts of transportation equipment are applied with various surface hardening treatments such as carburizing and induction hardening to prevent frictional wear with the gears on the other side, and higher functionality is required. Under the conditions, hard chrome plating or molybdenum-based thermal spray coating is applied on the upper layer. In recent years, various review of the part manufacturing process has been studied due to global environmental problems, and alternative methods for coating such as hard plating and thermal spraying are being sought for the purpose of reducing the manufacturing environment and reducing costs. Here, for the purpose of evaluating the suitability of the manufacturing method of the sliding member of the present invention for these applications, the friction and abrasion test shown in FIG. 1 is used, and seizure resistance with hard chromium plating and molybdenum spraying is used. A comparative test was conducted.

The discs and ring specimens for the frictional wear test were JIS-SCR415 steel, subjected to gas carburizing and quenching with a surface hardness of 720 HV and an effective carburization depth of about 0.5 mm, and used as a base material. Two types of test pieces for comparison were prepared by performing the following treatment on the surface of the base material.
Test piece 1: Hard chrome plating: surface hardness 760 HV, plating thickness ≈ 40 μm,
Test piece 2: Molybdenum spraying: surface hardness 700 HV, film thickness ≈ 50 μm

  Next, the test piece 3 according to the present invention forms a hard film using a tungsten-based electrode to a thickness of about 20 μm on the surface of the base material, and performs shot peening using a hard ball in the next step, The ceramic layer was removed, and the surface roughness was finished to 5 μm Ry. Further, the test piece 4 for high performance has a manganese phosphate-based chemical conversion coating on the surface of the test piece 3 to a thickness of about 3 μm, and the test piece 5 has a molybdenum disulfide-based solid lubricant on the surface of the test piece 3. The paint was coated to a thickness of about 9 μm. Further, the test piece 6 was prepared by coating the surface of the test piece 3 with a manganese phosphate-based chemical conversion treatment film with a thickness of about 3 μm + molybdenum disulfide-based solid lubricant paint with a thickness of about 9 μm. Table 4 shows the results of a series of tests performed on the above test pieces.

  From Table 4, the seizure load of the test piece 3 in which the surface roughness of the present invention is adjusted to 5 μm Ry is 160 kg, the test piece 1 for comparison is 160 kg, and the test piece 2 is 150 kg. Despite a thin film having a thickness of about 10 μm (test piece 3), seizure resistance almost equal to that of the current thick film (test pieces 1 and 2) was confirmed. Further, test pieces 4 to 6 in which manganese phosphate-based chemical conversion coating or molybdenum disulfide-based solid lubricating paint is treated alone and manganese phosphate-based chemical conversion treatment + molybdenum disulfide-based solid lubricating paint are combined are about 220 to 230 kg. It was confirmed that the seizure resistance was greatly improved.

  Next, when the variation of the friction coefficient until just before seizure is examined, in the test piece 3 in which the surface roughness of the electric discharge machining film is adjusted, μ≈0.08 to 0.10, and the test piece 1 μ≈0.0. It was almost equivalent to 07-0.10. On the other hand, the friction coefficients of the test pieces 5 and 6 of the present invention are μ≈0.03 to 0.05, and it was confirmed that the friction coefficient was greatly reduced.

In the present invention, a hard coating by electric discharge machining is formed on a surface of a metal material used for a sliding member such as a machine to a thickness corresponding to about 5 to 30 μm, and then the surface is shot, polished, chemically polished and electrolytic polished. discharging coating area ratio of the hard coating has 30% to 70% due, by controlling the surface roughness to 2～10MyumRy, surface hardening and PVD, such as conventional carburizing or induction hardening, a coating such as CVD, and Compared with thermal sprayed or various hard plated ones, a sliding member with much superior wear resistance, seizure resistance and adhesion can be obtained. Furthermore, in the application of sliding members with higher surface pressures, the optimum combination of chemical conversion treatment and solid lubricant is applied to these, and it is easy to reduce the friction coefficient and impart lubrication characteristics, molds, transportation equipment, industrial machinery, A wide range of utility value and durability improvement can be expected as a sliding member for electric machines.

The figure which shows the structure of a friction abrasion tester. It is a figure which shows the surface form by a scanning electron microscope, (a) is the state of the electrodischarge-processed film (no polishing), (b) is the electric discharge machined film being shot and polished, and the surface roughness is adjusted to 7 μmRy. (C) shows the surface state which adjusted the surface roughness to 1 micrometer Ry by the method similar to (b).

Explanation of symbols

1: Pressurization handle 2: Pressurization load cell 3: Torque meter 4: Test piece (ring)
5: Test piece (disc)
6: Oil bath 7: Rotating motor

Claims (3)

After forming a hard coating having a thickness of 5 to 30 μm by electric discharge machining in a hydrocarbon-based electric discharge machining liquid using a tungsten carbide consumable electrode on the surface of the metal material, the outermost layer of the coating is A method for producing a sliding member, characterized by polishing to a surface roughness of 2 to 10 μm Ry, maintaining the discharge film area ratio after polishing of the surface at 30% to 70% , and further subjecting the surface to a phosphate treatment .   The method for manufacturing a sliding member according to claim 1, wherein the polishing is performed by a physical method by shot, a mechanical method by polishing, or a chemical method by chemical polishing. Further, the production method of a sliding member according to claim 1 which processes the solid lubrication system at the top of the front surface.