JP2006348363A - Sliding member, its production method, and combination sliding member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sliding member which fits to the sliding surface of another side member in an early period even when the surface roughness of the other side member of the sliding surface is rough in an initial period and the sliding surface hardly attains a fluid lubricating state during sliding, and in which low wear and low friction can be attained. <P>SOLUTION: The slide member 1 is coated with a chemical conversion treatment film 2 having layers 8 formed by chemical conversion treatment and hard particles 5 dispersedly interposed among the layers 8, in which the crystalline particles 5 are the particles formed by manganese phosphate chemical conversion treatment. The crystalline particles 5 are the material capable of lapping the surface of the other side member on which the chemical conversion film 2 slides. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sliding member in which a chemical conversion coating is formed on a sliding surface, and more particularly to a sliding member that can be adapted to the sliding surface of a mating member at an early stage and can reduce wear and friction.

  Conventionally, a sliding surface of a differential gear of an automobile or a member such as a cam and a lifter has been required to have low friction. For example, in order to prevent seizure, a manganese phosphate chemical conversion treatment is applied to the sliding surface. Chemical conversion treatment such as iron phosphate chemical conversion treatment is performed. In addition, in the cam and lifter, the surface roughness of the sliding surface is reduced by applying a TiN coating with droplets on each sliding surface or by applying a resin coating containing hard particles such as SiC. In addition, friction is reduced.

  Other techniques for reducing the friction of the sliding surface include a method of mirroring the sliding surface and a resin coating containing a solid lubricant such as an amorphous carbon material or molybdenum disulfide. And the like.

  As an example, a coating film in which a chemical conversion treatment film is formed on the base material as a film having no polishing function, and hard particles having an acute-angle shape are bound by a resin binder as a film having a polishing function on the chemical conversion treatment film. There has been proposed a sliding material having a shape (see Patent Document 1).

  In addition, a phosphate chemical conversion coating is formed on the surface of the metal contact portion, and a lubricant coating of an inorganic polymer compound having a skeleton of Ti-O in which solid fine particles are dispersed and mixed is formed on the surface of the phosphate chemical conversion coating. A threaded joint for pipes has been proposed (see Patent Document 2).

Japanese Patent Laid-Open No. 2003-254014 JP 2001-65753 A

  However, as described above, when chemical conversion treatment is performed on the sliding surface, initial familiarity can be improved, but there is no effect of improving the surface roughness of the sliding surface, so friction is reduced. It takes a long time.

  In addition, when the sliding surface is coated with a TiN coating or a resin coating containing hard particles, the sliding surface of the mating member can be mirrored early during sliding. Since the film is formed by physical vapor deposition (PVD) using plating or the like, the film formation cost is high, and the processing space of the apparatus for performing PVD is limited, so the size of this sliding member is It will be restricted. When the film is formed by PVD, the film forming temperature is 200 ° C. or higher. Therefore, when the base material is steel, it is tempered and the surface hardness is reduced. Even in the case of applying a resin film, the curing temperature for softening and coating the resin is high, and the surface hardness decreases as in the case of the TiN film.

  In addition, as described above, when applying a resin film containing SiC particles or the like, it is easy to coat a flat sliding surface such as a valve lifter constituting the engine head, but it has a complicated shape such as a gear. Can only be applied by spraying, and the coating cost is high for such complicatedly shaped coating.

  Furthermore, it is effective to reduce the friction by mirroring the sliding surface. However, when mirroring the sliding surface with actual parts, not only the equipment investment is increased and the cost is increased, Processing time is also long.

  The present invention has been made in view of such problems, and the object of the present invention is early even if the surface roughness of the counterpart material of the sliding member is rough in the initial state. It is another object of the present invention to provide a sliding member that is compatible with the mating member and that can reduce wear and friction and a combined sliding member using the member. Furthermore, this invention is providing the manufacturing method which can manufacture such a sliding member cheaply.

  In order to achieve low wear and low friction of the sliding member by an inexpensive method by performing many experiments and researches to solve the above problems, the present inventors have performed an initial stage of sliding. (1) Accommodating the mating member so as to suppress adhesion wear due to seizure or the like (2) Surface roughness of the mating member so that the sliding surface changes from boundary mixed lubrication to fluid lubrication It was considered important to give the sliding member the two functions of reducing the size of the sliding member. Then, focusing on chemical conversion treatment as a means of improving initial conformability, focusing on wrapping as a means of reducing the surface roughness of the mating member, and from these viewpoints, chemical conversion treatment containing a wrapping agent (fine hard particles) It was found that these two functions can be satisfied simultaneously by forming the coating on the sliding surface.

  The present invention is based on the above-mentioned new knowledge obtained by the present inventors. The sliding member of the present invention comprises a layer formed by chemical conversion treatment, and hard particles dispersed and interposed in the layer. And a chemical conversion film having the following characteristics:

  The sliding member according to the present invention can avoid direct contact between the surface of the sliding member substrate and the surface of the mating member until it becomes compatible with the layer formed by the chemical conversion treatment. Since lubricating oil accumulates like a bit, initial familiarity with the surface of the mating member can be improved. And the hard particles intervened in the layer formed by the chemical conversion treatment polish the surface of the mating member, and at the same time, it is possible to achieve such an improvement in initial conformability and early mirror surface finishing. . As a result, even if the surface of the mating member is rough or the surface of the mating member has a large undulation, this sliding member will adapt to the mating member's surface at an early stage. Since the surface roughness of the member is reduced and the surface waviness is corrected, damage due to seizure or fatigue can be suppressed. Also, when lubricating oil is used, the surface roughness of the mating member is small, so that an oil film can be formed between the sliding member and the mating member, which is close to ideal fluid lubrication. It can slide in a state. The “hard particles” according to the present invention are particles having characteristics that are relatively harder than the surface hardness of the sliding surface of the mating member.

  Moreover, it is preferable that the layer formed by the chemical conversion treatment according to the present invention is formed by the manganese phosphate chemical conversion treatment or the iron phosphate chemical conversion treatment. The layer formed by the manganese phosphate chemical conversion treatment is a layer made of countless crystal particles of manganese phosphate, and the hard particles are dispersed and interposed between the crystal particles. Further, the layer formed by the iron phosphate chemical conversion treatment is a film made of amorphous iron phosphate, and hard particles are dispersed and interposed in this film. The layer formed by such a chemical conversion treatment has good adhesion to the surface of the base material, and can suppress adhesive wear with the counterpart member and prevent seizure. In particular, a treatment coating excellent in rust prevention and wear resistance can be formed by chemical conversion treatment with manganese phosphate. Furthermore, since such chemical conversion treatment can be performed at a treatment temperature of 100 ° C. or less, softening of the base material due to low-temperature tempering can be suppressed when the base material is steel.

  Further, the hard particles according to the present invention are materials capable of lapping the surface of the mating member on which the chemical conversion coating slides, and by incorporating such particles, the surface of the mating member during sliding The surface of the mating member can be mirror-finished. And even if the chemical conversion coating is worn away, the surface of the mating member is already mirror-finished after abrasion, and it slides while securing an oil film between the sliding member and the mating member. There is almost no contact (metal contact) between sliding surfaces, and there is almost no generation of wear powder.

  Further, in order that such hard particles can wrap the sliding surface of the mating member, the hardness of the surface of the mating member on which the sliding member slides is 1.2 to 5 times higher. It is preferable to have. When the hardness of the hard particles is smaller than 1.2 times the surface hardness of the mating member, there is almost no effect of wrapping the mating member, and the mating member cannot be mirrored at an early stage. Further, when the hardness of the hard particles is 5 times or more the surface hardness of the mating member, the sliding surface of the mating member is excessively polished, resulting in increased wear.

Preferably, the hard particles are particles selected from the group consisting of silicon nitride, silicon carbide, silicon oxide, aluminum oxide, niobium, tungsten, vanadium, and combinations thereof. In addition, the hard particles may be particles such as cubic boron nitride, chromium oxide, and diamond. For example, when a coating made of an amorphous carbon material (DLC: diamond-like carbon) is formed on the surface of the counterpart member, silicon carbide or niobium carbide is preferable if the coating has a surface hardness of about Hv2000. When the surface hardness of the coating is more than that, particles such as cubic boron nitride, B ₄ C, and diamond are preferable.

  Furthermore, the average particle diameter of the hard particles according to the present invention is preferably 0.1 to 1.5 μm. When the average particle size of the hard particles is smaller than 0.1 μm, the wrapping effect is hardly obtained, and when the average particle size is 1.5 μm or more, the wear of the mating member becomes large. The moving surface may be damaged.

  Moreover, it is desirable that the surface of the base material and the counterpart material of such a sliding member is at least Hv400 or more. If it is not such a range, the said hard particle may damage this surface, Furthermore, there exists a possibility that it may be embedded.

  The present invention further includes the above-described sliding member as a first member, and the first member and a second member in which a coating made of an amorphous carbon material is coated on a surface on which the first member slides. Also disclosed is a combination sliding member characterized by comprising.

  Since amorphous carbonized material (DLC) has a high surface hardness, it is necessary to reduce the surface roughness of the DLC film in order to suppress wear. For example, it is difficult to reduce the surface roughness of gears and the like. When a DLC film is applied to a member having a complicated shape, the first member can reduce the surface roughness of the DLC film during sliding by using such a sliding member in combination. This is preferable because it is possible. Further, such a combination member has a small friction coefficient and can extend the life of the member.

  In addition, when forming this DLC film, it may be formed by physical vapor deposition (PVD) using sputtering, vacuum vapor deposition, ionization vapor deposition, ion plating, etc., and plasma treatment is used. The film may be formed by chemical vapor deposition (CVD). Further, the amorphous carbon material may contain additional elements such as Si, Ti, Cr, Mo, Fe, and W.

  The present invention also discloses the following method as a preferred method for manufacturing the above-described sliding member. A manufacturing method of a sliding member according to the present invention is a method of manufacturing a sliding member by immersing a base material of a sliding member in a chemical conversion treatment liquid and performing a chemical conversion treatment on the surface of the base material. After mixing the hard particles in the liquid, the treatment liquid is stirred, and the chemical conversion treatment of the substrate surface is performed while the hard particles are precipitated on the substrate surface.

  By carrying out the production method as in the present invention, a sliding member coated with a chemical conversion coating having a layer formed by chemical conversion treatment and hard particles dispersed and interposed in the layer can be obtained. For example, when a chemical conversion treatment is performed on a base material made of an iron-based metal using a manganese phosphate aqueous solution as the chemical conversion treatment solution, the sliding member base material is immersed in the manganese phosphate aqueous solution. If it does, free phosphoric acid will arise by the primary dissociation of the manganese phosphate salt aqueous solution, the iron of the metal surface of a base material will melt | dissolve, and a hydrogen ion concentration will reduce on the base material surface. Then, the dissociation equilibrium of the manganese phosphate aqueous solution is transferred on the surface of the base material of the sliding member, and insoluble manganese phosphate crystal particles are precipitated on the metal surface. In this precipitation stage, the hard particles mixed in the chemical conversion solution are uniformly dispersed in the solution by stirring, and the dispersed hard particles are precipitated toward the substrate surface (sliding surface). The hard particles can be dispersed and interposed. Further, in such a manufacturing method, even if the member has a complicated shape, a uniform film can be formed by immersing the base material of the member. Therefore, the film is formed using a spray or the like. Compared to the case, the film can be formed at a lower cost.

  According to the present invention, even when the surface roughness of the mating member of the sliding member is rough in the initial state and the sliding surface is difficult to be in a fluid lubrication state during sliding, the sliding member is quickly mated. Since the sliding surface of the mating member is made to be familiar with the sliding surface of the member, the amount of wear can be reduced and the friction can be reduced.

  Hereinafter, the present invention will be described by way of examples.

[Example 1]
(Example product 1)
As an example product 1, a combined sliding member including a first member and a second member slid on the sliding surface of the first member was manufactured. First, as the base material of the first member, a cylinder made of chromium molybdenum steel (SCM420: JIS standard) carburized and quenched with an inner diameter of 20 mm, an outer diameter of 26 mm, a height of 15 mm, and a surface roughness of centerline average roughness Ra of 0.05 μm. A test piece was produced. Then, a manganese phosphate chemical conversion treatment liquid (manufactured by Parker Lines Japan, Inc .: Parfos 5A) as a chemical conversion treatment liquid is charged into the treatment tank, and hard particles made of silicon carbide (SiC) having a hardness Hv2500 and an average particle diameter of 0.5 μm. Is mixed in the treatment solution so that the amount of the solution becomes 1 to 3 wt%, and this solution is stirred, and this surface is directed upward so that hard particles of SiC are precipitated toward the cylindrical end surface (sliding surface) of the cylindrical test piece. And immersed in this solution at 95 ° C. for 20 minutes. In this manner, as shown in FIG. 1, the surface of the base material 3 is dispersed between the crystal particles 4 and the layer 8 (group of manganese phosphate crystal particles 4) formed by chemical conversion treatment. A cylindrical test piece (first member) 1 coated with a chemical conversion coating 2 having intervening hard particles 5 was obtained.

  Also, as the sliding member (second member), carburizing chrome molybdenum steel (SCM420: JIS standard) with 30 × 30 mm thickness 5 mm and surface roughness centerline average roughness Ra 0.3 μm. Quenching was performed to produce a flat plate test piece having a surface hardness of Hv750.

(contents of the test)
Friction and wear performance tests were performed using a ring-on-plate testing machine by combining the cylindrical specimen and the flat specimen of Example Product 1. Specifically, lubricating oil (SAE5W-30) is supplied, the end surface of the cylindrical test piece formed with the chemical conversion coating is brought into contact with the flat plate test piece, a load of 100 kgf (1000 N) is applied, and the flat plate test piece is fixed. The continuous test was performed for 30 minutes while rotating the cylindrical test piece at 1000 rpm. At this time, the sliding resistance acting on the cylindrical test piece was detected by a load cell attached to the apparatus, and the friction coefficient was measured. Furthermore, the wear depth of the surface of the flat test piece after the test was measured as the wear amount. The results are shown in Table 1. In addition, although not shown in Table 1, the surface state of the cylindrical test piece and flat plate test piece after a test was also observed.

[Example 2]
A cylindrical test piece and a flat plate test piece of Example Product 2 were produced. The difference from Example Product 1 is that an iron phosphate chemical conversion treatment liquid (manufactured by Nihon Parker Lines Co., Ltd.) was used as the chemical conversion treatment liquid for the cylindrical specimen, and as the hard particles, hardness Hv3300, average particle diameter The point is that 0.3 μm silicon nitride (Si ₃ N ₄ ) particles are used, and the hard particles are mixed in the treatment solution so as to be 2 to 4 wt%. By this treatment, the treated surface of the cylindrical test piece is interspersed with hard particles dispersed in an amorphous iron phosphate film. Using this Example Product 2, the same test as in Example 1 was performed. The results are shown in Table 1.

[Example 3]
A cylindrical test piece and a flat plate test piece of Example product 3 were produced. The difference from Example Product 1 is that the surface of the flat plate test piece is coated with a coating of an amorphous carbon material (DLC coating) having a surface hardness of Hv2000, and the surface roughness of the substrate is adjusted. This is the point that the surface roughness of this coating is centerline average roughness Ra 0.6 μm. Using this Example product 3, the same test as in Example 1 was performed. The results are shown in Table 1.

[Comparative Example 1]
Cylindrical test pieces and flat plate test pieces of Comparative Example Product 1 were produced. The difference from Example Product 1 is that the cylindrical specimen is not subjected to chemical conversion treatment. Using this comparative example product 1, the same test as in Example 1 was performed. The results are shown in Table 1.

[Comparative Example 2]
Cylindrical test pieces and flat plate test pieces of Comparative Example Product 2 were produced. The difference from Example 1 is that the cylindrical specimen is not subjected to chemical conversion treatment. Using the comparative product 2, the same test as in Example 1 was performed. The results are shown in Table 1.

[Result 1]
The wear depth of the flat plate test pieces of Examples 1 to 3 was 0.4 μm or less, and the friction coefficient of the combination sliding member of Examples 1 to 3 was 0.08 or less. On the other hand, the wear depth of the flat test piece of Comparative Example 1 was about the same as that of Examples 1 to 3, but the friction coefficient of the combination sliding member of Comparative Example 1 was larger than that of Examples 1 to 3. . Moreover, although the friction coefficient of the combination sliding member of the comparative example 2 was comparable as Examples 1-3, the wear depth of the flat test piece of the comparative example 2 was larger than Examples 1-3. .

  Moreover, the surface roughness of the flat plate test pieces of Examples 1 to 3 after the test is smaller than that before sliding (before the test), and the surface roughness crests are scraped to become flat surfaces. I found out. Furthermore, when the surface of the cylindrical test piece of Examples 1 to 3 after the test was observed, the chemical conversion coating was not present on the surface.

[Evaluation 1]
From the results 1 described above, the reason why the combined sliding members of Examples 1 to 3 were able to reduce wear and friction compared to Comparative Examples 1 and 2 is that the sliding start shown in FIG. Sometimes, the surface roughness of the flat test piece 6 is large, and even if the lubricating oil 7 is supplied, the surface of the flat test piece 6 comes into contact with the sliding surface of the cylindrical test piece (sliding member) 1. Thereafter, as shown in FIG. 2 (b), the surface of the cylindrical test piece 1 is quickly adapted to the surface of the flat plate test piece 6 by the layer formed by the manganese phosphate chemical conversion treatment or the iron phosphate chemical conversion treatment. At the same time, it is considered that the surface roughness of the flat plate test piece 6 was reduced by the hard particles, and the roughness crests were cut and lapped. Moreover, when there exists a wave | undulation in the surface of a flat plate test piece, it is thought that the wave | undulation is corrected similarly.

As a result, an oil film formed by the lubricating oil 7 is formed between the surface of the cylindrical test piece 1 and the surface of the flat plate test piece 6 at an early stage of sliding, and changes from boundary mixed lubrication to fluid lubrication. Thus, it is considered that the friction coefficient was reduced and the wear was also suppressed. And since there was no chemical conversion treatment film on the surfaces of the cylindrical test pieces of Examples 1 to 3 after the test, hard particles (SiC particles, Si ₃ N ₄ particles) were also lost, and thereby the flat plate test. It is considered that the surface of the piece 6 is not worn further.

  In addition, from the above consideration, the surface of the DLC film of the flat plate test piece of Comparative Example 2 was not able to reduce the surface roughness in accordance with sliding, so that the wear depth was larger than that of Example 3. It is thought that it became.

Further, as particles capable of lapping the surface of a flat plate test piece, as shown in Examples 1 to 3 in Table 1, the surface hardness obtained by carburizing and quenching SCM420 or the surface hardness harder than the surface hardness of the DLC coating It is necessary to be hard particles having hardness, and the hard particles of Example 1 are 3.3 times the surface hardness of the flat plate test piece, Example 2 is 4.4 times, and Example 3 is 1.25. Since it is about twice, it is thought that the hardness of this hard particle is preferably about 1.2 to 5 times the surface hardness of the flat plate test piece (mating member). If such a relationship can be satisfied, the hard particles are not limited to silicon carbide (SiC) and silicon nitride (Si ₃ N ₄ ), but silicon oxide, aluminum oxide, niobium, tungsten, vanadium. And a particle selected from the group consisting of combinations thereof.

  Moreover, the average particle diameters of the hard particles of Examples 1 to 3 are 0.3 μm and 0.5 μm, and the surface of the hard particles is mirror-finished by this hard particle to enable a fluid lubrication state when sliding. The average particle size of the hard particles is considered to be preferably in the range of 0.1 to 1.5 μm.

[Example 4]
In the same manner as the cylindrical test piece of Example product 1 was manufactured, the valve lifter 10 as shown in FIG. 3 was manufactured from chrome molybdenum steel (SCM420) and then carburized and quenched, while sliding with the cam 24. A manganese phosphate chemical conversion coating containing SiC as hard particles was formed under the same conditions as in Example Product 1.

  Then, a torque measurement test was performed using the valve lifter 10 of this example product 4. As shown in FIG. 3, a test was performed using a cylinder head unit tester 20 of a 2L (2000 cc) direct-acting valve-operated valve engine (in-line 4 cylinders). Specifically, an alloy cast iron chill cam 24 having a surface roughness center line average roughness Ra of 0.3 μm is connected to the motor 21, and a torque meter 22 is incorporated between the cam 24 and the motor 21, so that the rotational speed is 1000 rpm, The motor 21 was driven under the condition of the test time (sliding time) of 4 hours, and the cam drive torque was measured by the torque meter 22.

[Comparative Example 3]
A valve lifter was manufactured in the same manner as Example Product 4. The difference from Example Product 4 is that the manganese phosphate chemical conversion treatment was carried out without containing SiC particles. The comparative example product 3 was similarly subjected to a cam drive torque measurement test using the cylinder head unit testing machine 20.

[Result 2]
FIG. 4 shows a value (cam drive torque ratio) obtained by dividing the initial cam drive torque of Comparative Example 3 by the measured cam drive torque. The valve lifter of Example 4 is in the initial state (about 1 hour from the start of the test). ), The cam drive torque ratio suddenly decreased, and the cam torque ratio decreased to about 0.8. In Comparative Example 3, the cam drive torque ratio also decreased, but no significant decrease was observed as in Example 4.

[Evaluation 2]
From the result 2, when using a valve lifter in which hard particles are contained in the manganese phosphate chemical conversion coating as in Example 4, the hard particles (SiC particles) are brought into contact with the cam surface in the initial stage while the cam surface Since the wrapping is performed, the sliding surface of the valve lifter, the cam, and the sliding surface are considered to have reduced the friction coefficient and the driving torque at an early stage.

  The sliding member of the present invention is particularly suitable for a sliding member that is used in an environment where wear resistance is required, such as a valve lifter that constitutes a cylinder head of an internal combustion engine. When the combined sliding member of the invention is applied to a cylinder head of an internal combustion engine, the first member of the combined member is used for the sliding surface of the valve lifter constituting the cylinder head, and the combined sliding is used for the sliding surface of the cam. It is preferable to use the second member.

The schematic diagram of the surface of the sliding member (1st member) of Examples 1-3. The schematic diagram for demonstrating the surface state when sliding the combination sliding member of Examples 1-3. The figure which showed the principal part of the cylinder head unit testing machine of a direct stroke type valve-operated system engine. The figure which showed the torque measurement test result of Example 4 and Comparative Example 3. FIG.

Explanation of symbols

1: sliding member (cylindrical test piece), 2: chemical conversion coating, 3: base material, 4: crystal particles, 5: hard particles, 6: second member (flat plate test piece), 7: lubricating oil, 10: Valve lifter, 20: Cylinder head unit tester, 21: Motor, 22: Torque meter

Claims (8)

  A sliding member characterized by coating a chemical conversion treatment film having a layer formed by chemical conversion treatment and hard particles dispersed and interposed in the layer.   The sliding member according to claim 1, wherein the layer formed by the chemical conversion treatment is formed by a manganese phosphate chemical conversion treatment or an iron phosphate chemical conversion treatment.   The sliding member according to claim 1 or 2, wherein the hard particles are a material capable of wrapping the surface of a mating member on which the chemical conversion coating slides.   The sliding member according to any one of claims 1 to 3, wherein the hard particles have a hardness that is 1.2 to 5 times the surface hardness of the counterpart member.   5. The hard particle according to claim 1, wherein the hard particle is a particle selected from the group consisting of silicon nitride, silicon carbide, silicon oxide, aluminum oxide, niobium, tungsten, vanadium, and combinations thereof. The sliding member according to one item.   6. The sliding member according to claim 1, wherein an average particle diameter of the hard particles is 0.1 to 1.5 μm.   A first member made of the sliding member according to any one of claims 1 to 6, and a second member in which a coating made of an amorphous carbon material is coated on a surface on which the first member slides. A combination sliding member characterized by comprising. A method of manufacturing a sliding member by immersing a base material in a chemical conversion treatment liquid and performing a chemical conversion treatment on the surface of the base material,
A method for producing a sliding member, comprising mixing a hard particle in a chemical conversion treatment liquid, stirring the treatment liquid, and subjecting the base material surface to a chemical conversion treatment while precipitating the hard particles on the base material surface.

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