JP6133916B2 - Manufacturing method of sliding member and manufacturing method of piston - Google Patents

Description

  The present invention relates to a lubricating coating composition for coating a surface of a base material with a lubricating coating in which molybdenum disulfide particles are dispersed and the dispersed molybdenum disulfide particles are bonded with a binding resin, and sliding using the same The present invention relates to a member and a manufacturing method thereof.

  Conventionally, in order to improve the sliding characteristics of the sliding member, the surface of the base material is coated with a lubricating film. Such a lubricating coating contains, for example, polytetrafluoroethylene particles, graphite particles, molybdenum disulfide particles or the like as a solid lubricant, and these particles may be bonded resin (matrix) such as polyamideimide resin or polyimide resin. Resin). Thus, the slidability of the sliding member can be improved by including the solid lubricant in the lubricating coating.

  As such a technique, for example, Patent Document 1 proposes a sliding member in which a lubricant film composed of a resin binder and a solid lubricant of 40 to 60% by mass in total is formed on the surface of the base material. Here, the solid lubricant is composed of particles such as graphite and molybdenum disulfide, and the resin binder is polyamideimide resin, polybenzimidazole resin, or polyimide resin.

JP 2010-196813 A

  Here, as shown in FIG. 7, since a general lubricating coating 92 such as the lubricating coating disclosed in Patent Document 1 is coated on the surface 91a of the metal base 91, the surface of the lubricating coating 92 The roughness of 92a (that is, the roughness of the surface 9a of the sliding member 9) tends to depend on the roughness of the surface 91a of the substrate 91.

  However, when the average particle size of the particles 93 acting as a solid lubricant contained in the lubricating coating 92 (average particle size of the particles contained in the lubricating coating composition) is large, the surface roughness of the lubricating coating 92 is the base material. It may become rougher than the surface roughness of 91. Further, when the amount of particles 93 (content of particles contained in the lubricating coating composition) is increased with respect to the binding resin 94 in order to improve seizure resistance, the same phenomenon occurs.

  Thereby, even if the surface 91a of the base member 91 of the sliding member is further smoothed, the sliding surface of the sliding member is difficult to be smooth, and as a result, it is difficult to obtain a low friction sliding characteristic. There is.

  The present invention has been made in view of these points, and the object of the present invention is to reduce the surface roughness of the lubricating coating formed on the surface of the base material of the sliding member and An object of the present invention is to provide a composition for a lubricating coating in which the surface of the lubricating coating is easily smoothed, a sliding member using the composition, and a method for producing the same.

  In view of the above problems, the lubricating coating composition according to the present invention has a lubricating coating in which molybdenum disulfide particles are dispersed and the dispersed molybdenum disulfide particles are bonded with a binding resin on the surface of a metal substrate. A lubricating coating composition for coating, wherein the lubricating coating composition contains 50 to 70 mass% of the molybdenum disulfide particles with respect to the total amount of the molybdenum disulfide particles and the binding resin, The molybdenum disulfide particles have an average particle diameter in the range of 0.1 to 3.0 μm.

  According to the present invention, by containing 50 to 70% by mass of molybdenum disulfide particles, the initial familiarity characteristics are improved, and the surface of the lubricating coating is easily smoothed during sliding. Further, by setting the average particle diameter of the molybdenum disulfide particles to 0.1 to 3.0 μm, the particle diameter becomes small, and the surface of the lubricating coating is smoothed. Thereby, when the sliding member is used, since the surface of the lubricating coating is easily worn, the initial conformability of the lubricating coating (sliding member) can be improved.

  The reason for limiting the content of molybdenum disulfide particles and the numerical value of the average particle diameter will be described in detail in the following embodiments and examples. Here, it is preferable to use a polyamide-imide resin as the binding resin in consideration of the bonding property between the particles, the adhesion to the substrate surface, the heat resistance of the lubricating coating, and the like.

  When a lubricant film formed from the above-described lubricant film composition is coated on the surface of the base material to form a sliding member, a plurality of dimples are formed on the surface of the lubricant film, The protruding valley depth Rvk of the surface of the lubricating coating is in the range of 0.4 to 1.0 μm, and the center line average roughness Ra of the surface of the lubricating coating is in the range of 0.4 to 1.0 μm. preferable.

  As is clear from the experiments by the inventors described later, the relationship between the surface of the lubricating coating, that is, the protrusion valley depth Rvk of the sliding surface of the sliding member and the centerline average roughness Ra is made compatible. The low friction characteristic can be realized while enhancing the initial familiarity of the sliding surface of the sliding member.

  Further, when manufacturing such a sliding member, by projecting hard particles harder than the base material to the surface of the base material by shot peening, the protruding valley portion depth is applied to the surface of the base material. A surface on which a plurality of dimples are formed such that the thickness Rvk is in the range of 1.5 to 2.0 μm and the center line average roughness Ra is in the range of 1.5 to 2.0 μm, and the dimples are formed In addition, it is preferable to form the lubricating coating from the lubricating coating composition. Thereby, the sliding member which has the characteristic mentioned above can be manufactured easily.

  Such a sliding member may be applied to an engine piston, and a lubricating coating may be applied to the skirt portion of the piston.

  According to the present invention, the surface roughness of the lubricating coating formed on the substrate surface of the sliding member is reduced, and the surface of the lubricating coating is easily smoothed during sliding.

It is a schematic diagram for demonstrating the manufacturing method of the sliding member which concerns on this embodiment, (a) is a figure for demonstrating the surface treatment of a base material, (b) showed the surface-treated base material. The figure which showed the sliding member which coat | covered the lubricating film on the surface of the figure and (c). The figure which showed the surface roughness of the sliding member which concerns on Examples 1-3 and Comparative Examples 1-5. The figure for demonstrating the abrasion test of the sliding member which concerns on Examples 1-3 and Comparative Examples 1-5. The figure which showed the abrasion loss of the lubricating film of the sliding member which concerns on Examples 1-3 and Comparative Examples 1-5. The figure which showed the relationship between rotation speed -BMEP when using the piston which concerns on Example 4, 5 and the comparative example 6, and FMEP. The figure which showed the relationship between rotation speed -BMEP when using the piston which concerns on Example 5 and Comparative Example 7, and FMEP. The schematic diagram which showed the conventional sliding member.

  Hereinafter, an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram for explaining a manufacturing method of a sliding member according to this embodiment, wherein (a) is a diagram for explaining surface treatment of a substrate, and (b) is a surface-treated substrate. The figure which showed material, (c) is the figure which showed the sliding member which coat | covered the lubricating film on the surface of the base material.

1. About the composition for lubricating films The composition for lubricating films which concerns on this embodiment is a composition for coat | covering the lubricating film 20 on the surface 10b of the metal base materials 10, as shown in FIG.1 (c). . The lubricating coating composition contains molybdenum disulfide particles and a binding resin (resin binder) that binds the molybdenum disulfide particles as a main agent.

  The composition for lubricating coating contains 50 to 70% by mass of molybdenum disulfide particles with respect to the total amount of molybdenum disulfide particles and binding resin. The average particle diameter of the molybdenum disulfide particles is in the range of 0.1 to 3.0 μm.

As used herein, “particle diameter” refers to the volume cumulative average particle diameter (D ₅₀ ) measured by a laser diffraction / scattering particle size distribution measurement method, and “centerline average roughness Ra” It is a value measured according to JIS B 0601-1994, and “projection valley depth (oil sump depth) Rvk” is a value measured according to JIS B 0601-2001.

  In this embodiment, 50 to 70 mass% of molybdenum disulfide particles are contained, and the average particle diameter of the molybdenum disulfide particles is 0.1 to 3.0 μm. The surface roughness of the lubricating coating 20 formed on the surface 10b of the material 10 can be set to the same level as that of the surface 10b of the substrate 10. Thereby, the surface of the lubricating coating 20 can be smoothed. Furthermore, when the sliding member 1 is used, since the surface of the lubricating coating 20 is easily worn, the initial conformability of the lubricating coating 20 (sliding member 1) can be enhanced.

  Here, when the content of the molybdenum disulfide particles exceeds 70% by mass, or when the average particle diameter of the molybdenum disulfide particles exceeds 3.0 μm, the surface roughness of the formed lubricating coating 20 is obtained. May increase, and smoothing of the sliding surface 1a of the sliding member 1 may be hindered.

  On the other hand, when the content of the molybdenum disulfide particles is less than 50% by mass, the initial conformability of the sliding member 1 is deteriorated because the lubricating coating 20 is not easily worn at the initial acclimatization stage. It is difficult to produce molybdenum disulfide particles having an average particle size of less than 0.1 μm.

  Here, molybdenum disulfide particles having an average particle diameter in the range of 0.1 to 3.0 μm can be easily obtained by pulverizing and classifying commercially available molybdenum disulfide particles. Moreover, the average particle diameter of the molybdenum disulfide particle which can expect further the effect mentioned above is 0.5-1.5 micrometers.

  The binding resin is preferably a heat-resistant resin capable of binding molybdenum disulfide particles, for example, a resin selected from the group consisting of epoxy resins, phenol resins, polyamide resins, and polyamideimide resins, or these May be a polymer alloy containing one or more of them. Among these, the polyamide-imide resin has excellent heat resistance, little deterioration even when used in various lubricating oils, and good friction and wear characteristics.

  The lubricating coating composition used to form the lubricating coating is prepared by mixing the above-described molybdenum disulfide particles and the binding resin at the mixing ratio described above, using an appropriate organic solvent as a solvent, and stirring and mixing using a kneader or the like. Can be prepared. In addition, when manufacturing the composition for lubricating coatings, it is preferable to mix | blend molybdenum disulfide particle | grains in the state which melt | dissolved binder resin in the organic solvent previously.

  As the organic solvent, volatile aprotic polar solvents and the like are preferably used. Specifically, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, esters such as methyl acetate and ethyl acetate, aromatic hydrocarbons such as toluene and xylene, methyl chloroform, trichloroethylene, trichlorotrifluoroethane, etc. Organic halogen compounds such as N-methyl-2-pyrrolidone (NMP), methylisopyrrolidone (MIP), dimethylformamide (DMF), dimethylacetamide (DMAC), and the like. ) Can be used particularly preferably. A nonpolar solvent may be used as the organic solvent.

  Furthermore, the lubricant coating composition includes a dispersant that helps disperse the solid lubricant, a silane coupling agent that improves the adhesion between the solid lubricant and the resin, and the adhesion of the resin to the substrate, and the surface tension is controlled. A surfactant may be included. Furthermore, an appropriate amount of additives (such as an anti-precipitation agent, a thickener, an antifoaming agent, and a leveling agent) for improving storage stability and coating suitability may be added within a range not impairing the object of the present invention.

2. Sliding member and manufacturing method thereof First, a metal base material is prepared. The substrate is preferably a substrate made of one or more metals selected from aluminum, iron, copper, nickel, chromium, titanium, and the like, and may be a substrate made of an alloy containing these metals. . Furthermore, if desired, it may be a metal substrate subjected to a surface treatment such as alkali degreasing.

  Here, the surface roughness of the surface of the metal substrate can be appropriately set according to the use environment, and in the present embodiment, when a lubricating film is formed from the lubricating film composition described later, The surface roughness of the lubricating coating (the surface roughness of the sliding member) is close to the surface roughness of the substrate.

  For example, the lubricating coating composition may be formed by applying the lubricating coating composition to the surface (cut or ground surface) of the metal substrate shown in FIG. To smooth the surface of the substrate 10. Specifically, as shown in FIG. 1A, hard particles 40 harder than the base material 10 are sprayed onto the surface 10a of the base material 10 by shot peening. By this shot peening, the projecting valley depth Rvk is in the range of 1.5 to 2.0 μm and the center line average roughness Ra is in the range of 1.5 to 2.0 μm. The surface 10b on which the dimples are formed is formed (see FIG. 1B). Thereby, the surface 10b of the base material 10 optimal for exhibiting the effect of the composition for lubricating coating according to the present embodiment can be obtained.

  For example, in the case of a base material made of an aluminum alloy (Ai-Si alloy), hard particles 40 of an iron alloy having an average particle diameter of 20 to 300 μm are used in shot peening. First, the above-described hard particles 40 are jetted onto the surface 10a of the base material 10 under a condition that a predetermined arc height value is obtained in an atmosphere in which oxygen exists (for example, in the air).

  In this way, the surface 10b of the substrate 10 on which a plurality of dimples having the surface properties described above is formed can be obtained. The protruding valley depth Rvk and the centerline average roughness Ra can be adjusted by changing the shot particle size, shot injection conditions in the injection process, and the like.

  Next, the lubricant film 20 is coated with the lubricant film composition on the surface 10b of the base material 10 on which the dimples are formed. Coating on the surface 10b of the substrate 10 can be performed by a known method such as brush coating, spray coating, roll coating, screen printing, knife coating, pad coating, or dip coating, and is industrial. May be applied by air spray.

  After the lubricating coating composition is applied to the surface 10b of the substrate 10, the organic solvent in the composition is removed by heat treatment, and the surface of the substrate 10 is removed as shown in FIG. Furthermore, the lubricating coating 20 can be coated.

  The protruding valley depth Rvk on the surface of the obtained lubricating coating 20 is in the range of 0.4 to 1.0 μm, and the center line average roughness Ra of the surface of the lubricating coating 20 is in the range of 0.4 to 1.0 μm. Become. As a result, the relationship between the protrusion valley depth Rvk and the centerline average roughness Ra of the sliding surface 1a of the sliding member 1 is in the above-described range, so that the surface roughness of the sliding surface 1a is reduced. The oil retaining property of the lubricating oil can be enhanced on the sliding surface 1a in a lower state than before. Thereby, a low friction characteristic is realizable, improving the initial familiarity of the sliding face 1a of the sliding member 1. FIG.

  Here, the film thickness of the lubricating coating is arbitrary, but is preferably 6 to 16 μm. By making this range, when the molybdenum disulfide particles having the above average particle diameter are contained in the above range, this can be smoothed, and the sliding surface depends on the surface of the substrate, and the sliding surface Is easily within the above-described range. When the lubricating coating composition is applied to the sliding surface of the skirt portion of the piston to form a lubricating coating, it is possible to suppress a decrease in the thermal conductivity of the piston.

  Here, conventionally, when the surface of the substrate is polished with a grindstone or the like, the surface becomes a streak shape and the actual surface pressure increases, so a large amount of molybdenum disulfide particles are blended, and the initial familiarity Could not be improved. However, in the present embodiment, the lubricant film 20 is coated on the smoothed surface 10b of the substrate 10 by the ground treatment as described above, and the average particle diameter of the molybdenum disulfide particles contained in the lubricant film 20 is reduced. Thus, the actual surface pressure of the sliding surface 1a can be reduced and wear can be suppressed. As a result, even when more molybdenum disulfide particles are added, wear resistance is ensured without dropping particles, the initial conformability of the lubricating coating 20 is improved, and a smooth sliding surface is formed at an early stage. Can do.

  Examples of the present invention will be described below.

[Example 1]
As a base material of the sliding member, an aluminum alloy casting (JIS standard: AC8B) having a surface roughness Rz 0.8 μm (equivalent to Ra 0.2 μm) is prepared as 15.7 mm × 6.5 mm × 10.1 mm. The surface was alkali degreased.

  Next, molybdenum disulfide particles having an average particle diameter of 2 μm as a solid lubricant, and a polyamideimide resin (PAI) dissolved in NMP as an organic solvent as a resin for binding the particles, as shown in Table 1, The composition was blended so that the molybdenum disulfide particles were 50% by mass and the polyamideimide resin was 50% by mass (mass% of the resin excluding the organic solvent), and these were mixed to prepare a lubricating coating composition. Next, the base material is preheated at 80 ° C. for 30 minutes, the lubricating coating composition is coated on the surface of the base material, and this is heated at 180 ° C. for 90 minutes to form a film on the base material. A lubricating coating having a thickness of 13 μm was formed.

Here, the average particle size of the molybdenum disulfide particles was measured by a measurement method by PIDS (polarized light scattering intensity difference measurement) using a laser diffraction scattering type particle size distribution measuring apparatus (Microtrac MT300 manufactured by Nikkiso Co., Ltd.). . The average particle diameter was measured using NMP, the volume accumulated average particle diameter D ₅₀ of the molybdenum disulfide particles. Further, the ratio (mass%) of the molybdenum disulfide particles and the polyamideimide resin was weighed and measured.

[Example 2]
A sliding member was produced in the same manner as in Example 1. The difference from Example 1 is that, as shown in Table 1, the composition for lubricating coating was prepared by blending molybdenum disulfide particles at 60% by mass and polyamideimide resin at 40% by mass.

Example 3
A sliding member was produced in the same manner as in Example 1. The difference from Example 1 is that, as shown in Table 1, the composition for lubricating coating was prepared by blending so that the molybdenum disulfide particles were 70% by mass and the polyamideimide resin was 30% by mass.

[Comparative Example 1]
A sliding member was produced in the same manner as in Example 1. As shown in Table 1, the difference from Example 1 is that 20% by mass of molybdenum disulfide particles having an average particle diameter of 7 μm and an average particle diameter of 2% as a solid lubricant with respect to 70% by mass of polyamideimide resin. The lubricating coating composition was prepared by blending 7 μ% of 5 μm graphite particles and 3% by weight of polytetrafluoroethylene particles having an average particle diameter of 4 μm (PTFE).

[Comparative Example 2]
A sliding member was produced in the same manner as in Example 1. The difference from Example 1 is that, as shown in Table 1, the composition for lubricating coating was prepared by blending molybdenum disulfide particles at 40% by mass and polyamideimide resin at 60% by mass.

[Comparative Example 3]
A sliding member was produced in the same manner as in Example 1. The difference from Example 1 is that, as shown in Table 1, the composition for lubricating coating was prepared by blending molybdenum disulfide particles at 80 mass% and polyamideimide resin at 20 mass%.

[Comparative Example 4]
A sliding member was produced in the same manner as in Example 1. The difference from Example 1 was that, as shown in Table 1, the graphite particles used in Comparative Example 1 were blended so that the mass was 50% by mass and the polyamideimide resin was 50% by mass to prepare a lubricating coating composition. Is a point.

[Comparative Example 5]
A sliding member was produced in the same manner as in Example 1. The difference from Example 1 was that, as shown in Table 1, the PTFE particles used in Comparative Example 1 were blended so as to be 50% by mass, and the polyamideimide resin was 50% by mass to prepare a lubricating coating composition. Is a point.

<Measurement of surface roughness of lubricating coating>
The surface roughness (centerline average roughness Ra) of the lubricating coating of the sliding members according to Examples 1 to 3 and Comparative Examples 1 to 5 was measured. The centerline average roughness Ra is a value measured in accordance with JIS B0601-1994. The results are shown in Table 1 and FIG. FIG. 2 is a diagram illustrating the surface roughness of the sliding members according to Examples 1 to 3 and Comparative Examples 1 to 5. In addition, the broken line shown in FIG. 2 is the surface roughness of a base material.

<Initial familiarity test>
As shown in FIG. 3, a frictional wear test (a block test piece 51, a ring test piece 52, and a lubricating oil 53 corresponding to the sliding members of Examples 1 to 3 and Comparative Examples 1 to 5 shown above are combined. Block on-ring test: LFW-1 test, manufactured by FALEX).

  Specifically, as the ring test piece 52, a test piece made of gray cast iron (JIS standard: FC250) having an outer diameter of 35 mm, a width of 8.8 mm, and a surface roughness Rz of 0.8 μm was prepared. The lubricating oil 53 is applied to the oil bath 54 so that a part of the ring test piece is immersed in the lubricating oil 53, and the ring test piece 52 is rotated at a peripheral speed of 0.11 m / s while maintaining the oil temperature at 80 ° C. Then, an oil film was formed on the surface of the ring test piece 52, the block test piece 51 was brought into contact with the outer peripheral surface of the ring test piece 52, and a continuous test for 5 minutes was performed while applying a load of 22.5N.

  The wear depth of the lubricating coating of the sliding member, which is the block test piece 51 after the test was completed, was measured and used as the wear amount. In addition, base oil (commercial engine oil of SAE viscosity grade 0W-20) was used for lubricating oil. The results are shown in Table 1 and FIG. FIG. 4 is a diagram illustrating the amount of wear of the lubricating coating of the sliding members according to Examples 1 to 3 and Comparative Examples 1 to 5. In addition, the broken line shown in FIG. 4 is a lower limit value of the amount of wear at which initial familiarity is good from the inventors' experience.

(Result 1)
As shown in FIG. 2 and Table 1, the surface roughness of the lubricating coatings formed from the lubricating coating compositions according to Examples 1 to 3 was smaller than those of Comparative Examples 1, 3, 4, and 5. It was.

  That is, when a lubricant film is formed with the lubricant film composition according to Comparative Examples 1, 3, 4, and 5, the surface roughness of the lubricant film becomes rough. This is considered to be because, in Comparative Examples 1, 4 and 5, the average particle size of the solid lubricant contained in the lubricating coating composition is larger than those of Examples 1-3. On the other hand, in the case of Comparative Example 3, the content of the solid lubricant (molybdenum disulfide particles) contained in the lubricating coating composition is higher than those in Examples 1 to 3.

  On the other hand, as shown in FIG. 4 and Table 1, the amount of wear of the lubricating coating of the sliding members according to Examples 1 to 3 and Comparative Examples 3 to 5 is larger than those of Comparative Examples 1 and 2. This is considered due to the fact that the amount of molybdenum disulfide particles in the lubricating coating of the sliding members according to Examples 1 to 3 and Comparative Examples 3 to 5 is larger than those in Comparative Examples 1 and 2. . However, since the surface roughness of the lubricating coating of Comparative Examples 3 to 5 is larger than that of Examples 1 to 3, the oil film forming ability is low. Therefore, it can be said that the lubricating film of the sliding member according to Examples 1 to 3 has higher oil film forming ability and better initial adaptability than those of Comparative Examples 1 to 5.

  From the above, if the lubricating film composition contains 50 to 70% by mass of molybdenum disulfide particles and the average particle diameter is in the range of 0.1 to 3.0 μm, the lubricating film is a base material. It is considered that the surface roughness according to the surface roughness (having smoothness) is good and the initial familiarity is also good.

Example 4
As a sliding member, a piston (base material) of an internal combustion engine made of an AC8 series aluminum alloy casting was prepared, and the surface of the piston skirt was cut. Thereby, a plurality of streaks were formed on the surface of the skirt portion. Next, the protrusion valley depth (oil sump depth) Rvk was measured in accordance with JIS B 0610-2001 at a plurality of locations on the surface of the skirt portion, and the centerline average roughness Ra was measured by the method described above. . As a result, the maximum value of the protrusion valley depth Rvk is 1.0 μm, and the minimum value is 0.2 μm (protrusion valley depth Rvk: 0.2 to 1.0 μm), and the center line average roughness Ra is the maximum. The value was 4.8 μm, and the minimum value was 2.5 μm (center line average roughness Ra: 2.5 to 4.8 μm).

  A lubricating coating was formed on this surface using the same lubricating coating composition as in Example 1 under the same conditions as in Example 1. At a plurality of locations on the surface (sliding surface) of the lubricant film after film formation, the protruding valley depth Rvk and the centerline average roughness Ra were measured by the same method as described above. As a result, the protruding valley depth Rvk was in the range of 0.2 to 1.0 μm, and the centerline average roughness Ra was in the range of 2.5 to 4.8 μm.

Example 5
As in Example 4, a piston (base material) for an internal combustion engine made of an AC8-based aluminum alloy casting was prepared, and surface treatment was performed on the surface of the piston skirt. Specifically, a plurality of dimples were formed on the surface of the skirt portion by shot peening using hard particles harder than the base material (specifically, a shot made of an iron-based material having an average particle diameter of 50 μm). .

  Next, the protruding valley depth (oil sump depth) Rvk and the centerline average roughness Ra were measured at a plurality of locations on the surface of the skirt portion. As a result, the maximum value of the protrusion valley depth Rvk is 2.0 μm, and the minimum value is 1.5 μm (protrusion valley depth Rvk: 1.5 to 2.0 μm), and the center line average roughness Ra is the maximum. The value was 2.0 μm, and the minimum value was 1.5 μm (center line average roughness Ra: 1.5 to 2.0 μm).

  A lubricating coating was formed on this surface using the same lubricating coating composition as in Example 1 under the same conditions as in Example 1. At a plurality of locations on the surface (sliding surface) of the lubricant film after film formation, the protruding valley depth Rvk and the centerline average roughness Ra were measured by the same method as described above. As a result, the protrusion valley depth Rvk was in the range of 0.4 to 1.0 μm, and the center line average roughness Ra was in the range of 0.4 to 1.0 μm.

[Comparative Example 6]
A piston (base material) for an internal combustion engine made of an AC8-based aluminum alloy casting as in Example 4 was prepared, and the surface of the skirt portion of the piston was cut in the same manner as in Example 4. Thereby, a plurality of streaks were formed on the surface of the skirt portion. The protruding valley depth Rvk and the centerline average roughness Ra on the surface of the skirt were in the same range as those in Example 4.

  A lubricating film was formed on this surface under the same conditions as in Comparative Example 1 using the same lubricating film composition as in Comparative Example 1. The protruding valley depth Rvk and the centerline average roughness Ra were measured at a plurality of locations on the surface (sliding surface) of the lubricating coating after film formation. The protruding valley depth Rvk and centerline average roughness Ra of Comparative Example 6 were in the same range as those of Example 4.

[Comparative Example 7]
As in Example 5, a piston (base material) for an internal combustion engine made of an AC8 series aluminum alloy casting was prepared, and a plurality of dimples were formed on the surface of the skirt portion by shot peening on the surface of the skirt portion of the piston. . The protruding valley depth Rvk and the centerline average roughness Ra on the surface of the skirt portion were the same as those in Example 5.

  A lubricating film was formed on this surface under the same conditions as in Comparative Example 1 using the same lubricating film composition as in Comparative Example 1. The protruding valley depth Rvk and the centerline average roughness Ra were measured at a plurality of locations on the surface (sliding surface) of the lubricating coating after film formation. The protruding valley depth Rvk and centerline average roughness Ra of Comparative Example 7 were in the same range as those of Example 5.

<Real machine test>
Using the pistons according to Examples 4 and 5 and Comparative Examples 6 and 7, actual machine tests were performed. Specifically, the displacement was about 660 cc, the cylinder bore diameter was 94 mm, the stroke was 95 mm, 0 W-20 was used for engine oil, and the oil water temperature was set to 80 ° C. ± 1 ° C. Next, the friction average effective pressure (FMEP) was measured while gradually increasing the rotation speed to 2000 rpm and changing the net average effective pressure (BMEP). These results are shown in FIG. 5 and FIG. FIG. 5 is a diagram showing the relationship between the rotational speed -BMEP and the FMEP when the pistons according to Examples 4 and 5 and Comparative Example 6 are used. FIG. 6 is a diagram showing the relationship between the rotational speed -BMEP and the FMEP when the pistons according to Example 5 and Comparative Example 7 are used.

(Result 2)
As shown in FIG. 5, the friction average effective pressure (FMEP) of Example 4 and Example 5 is lower than that of Comparative Example 6, and in particular, the friction average effective pressure (FMEP) of Example 5 is It was lower than 4. As shown in FIG. 6, the friction average effective pressure (FMEP) of Example 5 was lower than that of Comparative Example 7.

  From this, in Examples 4 and 5, by using the lubricating coating composition according to Example 1, even if it contains molybdenum disulfide particles, it is made larger than the surface roughness of the substrate. This is probably because the lubricating coating could be formed without any problems. As a result, the lubricating coatings of Examples 4 and 5 are likely to form an oil film, so the FMEP of Examples 4 and 5 is considered to be lower than that of Comparative Example 6.

  In particular, in the case of the lubricating coating of Example 5, the protruding valley depth (oil sump depth) Rvk is larger than that of Example 4 although the center line average roughness Ra is smaller. . Thereby, in the case of Example 5, a thicker oil film is more easily formed than that of Example 4, and the FMEP of Example 5 is considered to be lower than that of Example 4. However, in the case of Comparative Example 7, since the lubricating coating composition according to Comparative Example 1 was used, it was difficult to depend on the surface state of the substrate, and the FMEP of Comparative Example 7 was larger than that of Example 5. It is thought that it became.

  Furthermore, when a plurality of surface roughnesses of the lubricant film on the skirt portion after the actual machine test were measured, the surface roughness (for example, Ra 2.1 μm) of the lubricant film according to Example 4 was that of Comparative Example 6 (for example, Ra 2.3 μm). ). Similarly, the surface roughness (for example, Ra 0.72 μm) of the lubricating coating according to Example 5 was smaller than that of Comparative Example 7 (for example, Ra 1.01 μm). These surface roughness relationships were the same as those before the actual machine test. From this result and the above-described FMEP result, it is considered that the sliding members according to Examples 4 and 5 have higher initial familiarity than those of Comparative Examples 6 and 7.

  The embodiment of the present invention has been described in detail above. However, the present invention is not limited to the above-described embodiment, and is within the scope of the present invention described in the claims and the specification. Various design changes can be made.

1: sliding member, 1a: sliding surface, 10: substrate, 10b: surface of substrate, 20: lubricating coating

Claims (3)

A lubricating coating composition for coating a surface of a metal base material with a lubricating coating in which molybdenum disulfide particles are dispersed and the dispersed molybdenum disulfide particles are bonded with a binding resin, the lubricating coating composition The product contains 50 to 70% by mass of the molybdenum disulfide particles with respect to the total amount of the molybdenum disulfide particles and the binding resin, and the molybdenum disulfide particles have an average particle diameter of 0.1 to 3.0 μm. the lubricant film from lubrication coating composition is in the range, a manufacturing method of a sliding member to be formed on the surface of the substrate,
By spraying hard particles harder than the base material on the surface of the base material by shot peening, the protrusion valley depth Rvk is in the range of 1.5 to 2.0 μm on the surface of the base material, and And molding a plurality of dimples so that the center line average roughness Ra is in the range of 1.5 to 2.0 μm,
A method for producing a sliding member, comprising forming the lubricating coating from the lubricating coating composition on a surface on which the dimples are formed. The method for manufacturing a sliding member according to claim 1, wherein the binding resin is a polyamide-imide resin. A method for producing the piston by using the sliding member as a piston by the method for producing a sliding member according to claim 1 or 2 ,
A method for manufacturing a piston, comprising forming the plurality of dimples on a surface of a skirt portion of the piston and then covering the surface on which the dimples are formed with the lubricating coating.

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