JP2018189129A - Sliding member and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sliding member having a resin overlay improved in abrasion resistance.SOLUTION: A sliding member 100 includes a base material 10 made of a metal material, and a resin overlay 20 as a coating layer coating at least a part of a surface of the base material 10. The resin overlay 20 is a thin film which includes a resin component, a solid lubricant mixed in the resin component, and inorganic nanoparticles having an average particle diameter within a range of 5-300 nm. The inorganic nanoparticles are preferably SiC particles.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sliding member represented by, for example, a bearing, a cylinder, and a piston, and a method for manufacturing the same.

  The sliding member is indispensable for generating power in automobiles, ships, aircraft, industrial machines and the like. In recent years, with the promotion of fuel efficiency reduction of automobiles, the number of engine start / stops by idling stop and the operation frequency at low speed are increasing. Therefore, the increase in the number of solid contacts between materials increases the amount of wear and material damage such as seizure. Further, low friction in the poor lubrication region is also required. As a method for realizing these simultaneously, surface modification of the sliding member has attracted attention.

  For example, in plain bearings, texturing technology for forming micro grooves on the sliding surface and overlay technology for forming a soft coating have already been put into practical use, and gentle initial conformance and seizure resistance have been improved. (Non-Patent Document 1). In metal alloys, techniques such as addition of hard particles and refinement of crystal grains are applied to improve wear resistance. Even in resin overlays, there is a report example in which wear resistance is reduced by adding hard particles (for example, Non-Patent Document 2). However, in these conventional techniques, the initial conformability is improved as compared with the soft metal, but the wear resistance still has room for improvement.

Takayuki Doi, Kazuaki Enomoto, Hatsuhiko Usami, “Influence of MoS2 on Friction Properties of Resin Overlay”, 23rd Mechanical Materials and Materials Processing Technology Lecture Meeting of the Japan Society of Mechanical Engineers (M & P 2015) Toshiyuki Sennen, Amane Kamiya, Satoshi Kubota, Takashi Kajikawa, “Improvement of wear resistance of solid lubricant overlay containing SiC”, Tribology Conference 2012 Autumn Hokkaido Proceedings

  It is an object of the present invention to provide a sliding member having a resin overlay with improved wear resistance.

  As a result of intensive studies, the present inventors have found that the above problem can be solved by adding inorganic nanoparticles that can be expected to have a finer resin overlay structure to the coating layer (resin overlay).

That is, the sliding member of the present invention comprises a base material made of a metal material,
A coating layer covering at least a portion of the surface of the substrate;
With
The sliding member is a sliding member that slides relative to the mating member with the portion where the coating layer is formed as a sliding surface.
And the sliding member of this invention is a thin film in which the said coating layer contains the resin component, the solid lubricant mixed with the said resin component, and the inorganic nanoparticle within the range whose average particle diameter is 5-300 nm. It is characterized by being.

  In the sliding member of the present invention, the inorganic nanoparticles may be SiC particles.

  In the sliding member of the present invention, the content of the inorganic nanoparticles may be in the range of 0.5 to 20% by weight with respect to the entire constituent material of the coating layer.

  In the sliding member of the present invention, the sliding surface may form a bearing raceway surface or a guide surface.

The manufacturing method of the sliding member of this invention is a manufacturing method of the sliding member which has a coating layer which forms a sliding surface on the surface of a base material, and slides with the other member on the said sliding surface.
And the manufacturing method of the sliding member of this invention is the coating film containing the resin component, the solid lubricant, and the inorganic nanoparticle in the range whose average particle diameter is 5-300 nm on the surface of the base material which consists of metal materials. Forming a step;
Heat-treating the coating film to cure the resin component to form the coating layer;
It is characterized by including.

  The manufacturing method of the sliding member of this invention may use a spin coat method in the process of forming the said coating film.

  Since the sliding member of the present invention is excellent in wear resistance, it can be suitably used as parts such as bearings, cylinders, and pistons in various devices such as automobiles, ships, aircrafts, and industrial machines.

  Moreover, according to the manufacturing method of the sliding member of this invention, the sliding member excellent in abrasion resistance can be manufactured by the simple method of adding an inorganic nanoparticle to a coating layer.

It is principal part sectional drawing which shows the structure of the sliding member of one embodiment of this invention. It is drawing which shows the sliding distance change of the friction coefficient of each test piece in an Example and a comparative example. It is drawing which shows the specific abrasion loss and Vickers hardness after the test in an Example and a comparative example. It is drawing which shows the roughness of the other party member (ball surface) after the test in an Example and a comparative example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. FIG. 1 is a partial cross-sectional view showing a structure near the surface of a sliding member having a coating layer according to an embodiment of the present invention. The sliding member 100 includes a base material 10 made of a metal material and a resin overlay 20 as a coating layer that covers at least a part of the surface of the base material 10.

  Examples of the sliding member 100 include a bearing, a cylinder, and a piston. The sliding member 100 has a sliding surface 30 that slides relative to a mating member (not shown). In the sliding member 100 of the present embodiment, a part or the whole of the portion where the resin overlay 20 is formed slides relative to the mating member (not shown) as the sliding surface 30.

  For example, a bearing, which is a representative example of the sliding member 100, is a member that mainly holds a rotational motion or a motion of a linearly moving shaft and a load applied by the motion. This bearing is simply called a bearing when the shaft makes a rotational motion, and its name is subdivided according to the nature of the rotational motion, and includes a rolling bearing, a sliding bearing, and the like. On the other hand, when the shaft makes a linear motion, it is called a guide or a linear bearing. The names are subdivided according to the nature of the linear motion, and there are a sliding guide, a rolling guide, a static pressure guide, a magnetic levitation guide, and the like. For example, in a sliding bearing and a sliding guide, the shaft directly contacts the bearing and the guide. Further, in the rolling bearing and the rolling guide, a rolling element exists between the shaft and the bearing, and the rolling element contacts the bearing and the guide. In the bearing and the guide, the surfaces in contact with the shaft or the rolling element are referred to as the bearing raceway surface and the guide surface, respectively, but the sliding surface 30 in the sliding member 100 is used in a generic name.

  The base material 10 is not particularly limited as long as it is a metal material having sufficient mechanical strength and workability as a sliding part. For example, an aluminum-containing material such as pure aluminum or aluminum alloy; carbon alloy steel, carburized steel And iron-containing materials such as stainless steel; metals such as magnesium, titanium, zinc, copper and copper alloys. Among these, an aluminum-containing material containing 50% by weight or more, preferably 80% by weight or more of aluminum is preferable because it is lightweight and has excellent workability. Here, the aluminum alloy may be, for example, a wrought material or a casting material. The casting material may be produced by a die casting method or may be produced by a die casting method. The aluminum-containing material satisfying such conditions is, for example, a 1000 series material (pure aluminum), a 2000 series material (Al—Cu—Mg series alloy), and 3000 series as defined in JIS H 4000. Material (Al-Mn alloy), 4000 material (Al-Si alloy), 5000 material (Al-Mg alloy), 6000 material (Al-Mg-Si alloy), 7000 material (Al- Zn-Mg alloy), 8000 material (Al-Li alloy) and the like. Moreover, as a casting material, AC1A type material (Al-Cu type alloy), AC1B type material (Al-Cu-Mg type alloy), AC2A, AC2B type material prescribed | regulated in JISH5202 or JISH5302, for example (Al-Cu-Si based alloy), AC3A based material (Al-Si based alloy), AC4A, AC4C, AC4CH based material (Al-Si-Mg based alloy), AC4B based material (Al-Si-Cu based alloy) AC4D material (Al-Si-Mg-Cu alloy) AC5A material (Al-Cu-Ni-Mg alloy), AC7A material (Al-Mg alloy), AC8A, AC8B, AC8C material (Al -Si-Cu-Ni-Mg alloy), AC9A, AC9B (Al-Si-Cu-Mg-Ni alloy), ADC1 material, ADC3 material, ADC5 Material, ADC 6 based material, ADC10 material, ADC10Z based material, ADC 12 based material, ADC12Z based materials include ADC14 based material. Among these, it is more preferable to contain 0.01% by weight to 5% by weight of copper because it is excellent in hardness and wear resistance.

  The resin overlay 20 that is a coating layer contains a resin component, a solid lubricant mixed in the resin component, and inorganic nanoparticles having an average particle diameter of 5 to 300 nm dispersed in the resin component.

  As the resin component, a material that is generally applied to the resin overlay 20 can be used without any particular limitation. For example, resins such as polyamideimide (PAI) and polyimide (PI) that are excellent in heat resistance can be preferably used.

As the solid lubricant, a material that is generally applied to the resin overlay 20 can be used without any particular limitation. For example, MoS ₂ , polytetrafluoroethylene (PTFE), or the like can be preferably used.

  The inorganic nanoparticles have an average particle diameter of 5 to 300 nm, preferably 10 to 100 nm, in order to promote the refinement of the structure of the resin overlay 20. If the average particle diameter of the inorganic nanoparticles is less than 5 nm, the effect of addition cannot be obtained, and if it exceeds 300 nm, protrusions due to coarse particles are generated on the surface of the resin overlay 20 and cause damage to the counterpart member.

The inorganic nanoparticles are preferably hard nanoparticles having a Vickers hardness of 1500 or more. Examples of such hard nanoparticles include silicon carbide (SiC) particles and silicon nitride (Si ₃ N _4). ) Particles and diamond particles. When the hardness of the inorganic nanoparticles is softer than the surface of the counterpart material, for example, less than 700 in the case of hardened steel, the effect of improving wear resistance becomes insufficient. Moreover, since improving the thermal conductivity of the resin overlay 20 is important for stabilizing the friction characteristics, it is preferable that the inorganic nanoparticles have a thermal conductivity comparable to that of a metal of, for example, 100 W / mK or more. .

The blending amount of the solid lubricant in the resin overlay 20 is preferably, for example, in the range of 20 to 60% by volume, and more preferably in the range of 30 to 50% by volume with respect to the entire constituent material of the resin overlay 20. If the blending amount of the solid lubricant is out of the above range, the friction reducing effect by the solid lubricant cannot be sufficiently obtained. In particular, the amount of MoS ₂ used as the solid lubricant is preferably in the range of, for example, 25 to 40% by volume with respect to the entire constituent material of the resin overlay 20.

  Moreover, the compounding quantity of the inorganic nanoparticles in the resin overlay 20 is preferably within a range of 0.5 to 20% by weight, for example, within a range of 0.5 to 10% by weight with respect to the entire constituent material of the resin overlay 20. More preferably, it is in the range of 1 to 5% by weight. If the blending amount of the inorganic nanoparticles is less than 0.5% by weight, the effect of improving the wear resistance cannot be sufficiently obtained, and if it exceeds 20% by weight, the resin overlay 20 tends to be easily peeled off from the substrate 10. .

  The thickness of the resin overlay 20 is preferably in the range of 2 to 10 μm, and more preferably in the range of 3 to 7 μm. When the thickness of the resin overlay 20 is less than 2 μm, the damage prevention effect and low friction of the base material 10 are insufficient.

[Sliding member manufacturing method]
The manufacturing method of the present embodiment is a manufacturing method of the sliding member 100 that has the resin overlay 20 that forms the sliding surface 30 on the surface of the base material 10 and slides with the mating member on the sliding surface 30. The manufacturing method of the sliding member 100 of this Embodiment can include the following processes a and b.

Step a:
Step a is a step of forming a coating film containing a resin component, a solid lubricant, and inorganic nanoparticles having an average particle diameter in the range of 5 to 300 nm on the surface of the base material 10 made of a metal material.
Formation of a coating film is performed by apply | coating the mixture which mixed the resin component, the solid lubricant, and the inorganic nanoparticle on the surface of the base material 10 by a well-known application | coating method. The order of mixing the components is not limited, but it is preferable to add a solid lubricant and inorganic nanoparticles to a resin component containing a solvent and stir uniformly.

There is no restriction | limiting in particular as an application | coating method, For example, it can apply | coat with a known coater etc. In the case of using MoS ₂ as the solid lubricant, a spin coating method that can enhance the orientation of the (002) plane of MoS ₂ and create a state that easily functions as a solid lubricant is preferable.

  Prior to step a, it is preferable to provide a step of forming an uneven surface by machining on at least a part of the surface of the substrate 10. By forming an uneven surface on the surface of the substrate, the adhesiveness with the resin overlay 20 can be enhanced. The machining is not limited as long as the machining method can mechanically form an uneven surface on the surface of the substrate 10. Examples of the machining include cutting, plastic working (shot peening, rolling), and electrochemical etching, and these processing methods may be combined. Among these, it is easy to control the size of the concavo-convex surface to be formed, excellent in forming speed, and can apply compressive residual stress in the vicinity of the concavo-convex surface. A shot peening method capable of improving the properties and the like is preferable. Examples of the projecting particles used in the shot peening method include metal balls such as iron and stainless steel, ceramic balls such as zirconia, silica, and alumina, and glass balls. Moreover, the mixed particle of multiple types of projection particle | grains may be sufficient. From the viewpoint of suppressing erosion, stainless steel shots and glass beads having an average hardness of 150 Hv to 550 Hv are preferable. The average particle diameter of the projected particles is not particularly limited, but is preferably 10 μm or more, more preferably 20 μm or more, and preferably 1000 μm or less, more preferably 100 μm or less, from the viewpoint of ensuring smoothness of the processed surface. . From the viewpoint of suppressing erosion, the gas pressure during projection of the projected particles is preferably 0.3 to 0.6 MPa, and the projection distance is preferably 20 to 100 mm. Moreover, although the gas to be used is not limited, compressed air is preferable for reasons of economy. The particle flow rate is preferably 1 to 10 g / min from the viewpoint of erosion suppression and the like. The shape of the uneven surface is preferably, for example, a groove shape, a dimple shape, or a streak shape.

Step b:
Step b is a step of forming the resin overlay 20 by curing the resin component by heat-treating the coating film. Although the temperature of heat processing can be suitably set according to the kind of resin component to be used, For example, the inside of the range of 150 to 250 degreeC is preferable. When the heat treatment temperature is less than 150 ° C., the resin component may be incompletely cured, or the resin overlay 20 may not be baked sufficiently, and the adhesion with the substrate 10 may be reduced. If it exceeds 1, the resin component may be decomposed. The heat treatment time can be appropriately set according to the type of resin component and the heat treatment temperature. For example, when the resin component is polyamideimide (PAI) and the heat treatment temperature is 200 to 220 ° C., the heat treatment time is preferably within a range of 30 minutes to 2 hours, and more preferably around 1 hour. The heat treatment may be performed under normal pressure or reduced pressure, but is preferably performed under reduced pressure. Moreover, you may carry out in inert gas atmosphere, such as nitrogen gas and argon gas.

  In addition, prior to the heat treatment, for example, it is preferable to perform a calcining process at a temperature in the range of 150 ° C. to 250 ° C. to perform a drying process for volatilizing the organic solvent in the coating film.

  As described above, the sliding member 100 in which the resin overlay 20 is formed on the surface of the substrate 10 is obtained. The sliding member 100 can be preferably applied to, for example, a bearing, a cylinder, and a piston of a bearing. When the sliding member 100 is used as a bearing raceway surface and a guide surface, the resin overlay 20 that forms the sliding surface 30 is a load from the viewpoint of achieving both high friction resistance and suppression of damage to the counterpart member. The Vickers hardness at 50 mN is preferably 70 Hv or more and 85 Hv or less.

  The sliding member 100 is excellent in wear resistance of the sliding surface 30 by the resin overlay 20. Therefore, for example, it can be suitably used as a sliding member such as a bearing, a cylinder, or a piston of a bearing. The sliding member 100 can be preferably applied as a sliding member such as a bearing of a bearing, a cylinder, or a piston in an apparatus such as an automobile, a ship, an aircraft, or an industrial machine that is lightweight and requires wear resistance.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. In the following examples, various measurements and evaluations are as follows unless otherwise specified.

[Measurement of average particle size]
The size of 300 particles was randomly measured based on a photograph taken with a transmission electron microscope, and the average particle diameter D50 of primary particles was calculated based on the number.

[Hardness measurement]
A diamond indenter was pressed with an applied load of 50 mN with a micro Vickers hardness tester (DUH201-WS manufactured by Shimadzu Corporation), and the Vickers hardness of the resin overlay was measured.

[Dynamic hardness DHV, elastic modulus measurement]
A Vickers indenter was pushed with a pushing load of 0.5 mN using a micro Vickers hardness tester (DUH201-WS manufactured by Shimadzu Corporation), and the dynamic hardness and elastic modulus of the resin overlay were measured. The measurement location was measured by observing the sample surface with an optical microscope and removing the molybdenum sulfide particles.

<Resin overlay material>
・ Resin component: Polyamideimide (PAI)
Solid lubricant: molybdenum disulfide (MoS ₂ )
・ Nano SiC particles (average particle size 50 nm, Nippon Steel & Sumikin Chemical Co., Ltd.)
・ SiC particles (average particle size: 4.0 μm)

[Example 1]
As a disk test piece, an aluminum cast alloy (AC8A) was used, which was turned to a diameter of 44 mm, an inner diameter of 20 mm, and a thickness difference of 8 mm. The surface of the disk specimen is subjected to fine particle projection using glass beads (FGB-180) having a particle size of about 90 μm under the conditions of particle acceleration pressure 0.6 MPa and flow rate control pressure 0.3 MPa. Was granted.

By blending 2% by weight of nano-SiC particles as inorganic nanoparticles with polyamideimide (PAI) resin containing 40% by volume of molybdenum disulfide (MoS ₂ ), the resin overlay material mixture Was prepared. A coating film of the resin overlay material was formed by applying this resin overlay material mixture to the disk test piece by spin coating at a rotational speed of 8000 rpm.

  Next, the disk test piece on which the coating film was formed was calcined on a hot plate heated to 220 ° C. to volatilize the solvent in the resin, and then thermally cured at 220 ° C. for 1 hour in a vacuum drying furnace. By performing the treatment, a resin overlay having a layer thickness of about 5 μm was baked on the surface of the base material to prepare a resin overlay test piece a.

[Comparative Example 1]
A resin overlay test piece b was prepared in the same manner as in Example 1 except that the nano SiC particles were not blended and spin coating was performed at a rotational speed of 8600 rpm.

[Comparative Example 2]
A resin overlay test piece c was prepared in the same manner as in Example 1 except that SiC particles having an average particle diameter of 4.0 μm were used as the inorganic particles instead of the nano SiC particles.

<Lapping process>
For the resin overlay test pieces a to c obtained in Example 1 and Comparative Examples 1 and 2 above, a diamond slurry having a particle diameter of 1 μm is used on the surface of the resin overlay in order to make the surface roughness of the resin overlay the same level. Wrapping treatment was applied.

<Hardness test>
Tables 1 and 2 show the results of hardness measurement, dynamic hardness, and elastic modulus measurement of the resin overlay.

<Friction and wear test>
The evaluation of the friction characteristics of the resin overlay was performed using a 3-ball on disk type friction tester. As the mating member, 1/4 inch (6.35 mm) diameter steel balls for chrome bearings (SUJ2) are used, and the same as the resin overlay test pieces a to c so that the contact portion diameter becomes a flat surface of 1.5 mm. A lapping treatment was applied to the.
Torque detector in which a jig with three balls mounted at equal intervals on the same circumference is rotated and the friction torque when the resin overlay test pieces a to c are pressed and slid from below is attached to the disk support shaft And recorded at a sampling period of 1 Hz.
For the lubricating oil, poly-α-olefin (PAO) was used, and a predetermined amount (80 μL) was dropped on the surface of the resin overlay before pressing the disk to start the test while covering the entire sliding surface. Refueling was not performed. The rotational speed was 0.5 m / s, the surface pressure was 37 MPa, and the sliding distance was 1000 m.
During the test, the case where the coefficient of friction increased rapidly was judged as “peeling”. In addition, the resin overlay before and after the test and the surface state of the mating member (ball) were observed with a microscope, and the surface roughness Ra of the mating member (ball) was measured.

<Test results>
FIG. 2 shows the change in the sliding distance of the friction coefficient of each test piece, FIG. 3 shows the specific wear amount and Vickers hardness after the test, and FIG. 4 shows the roughness of the mating member (ball surface) after the test. The specific wear amount W _S was calculated based on the following equation (1).
W _S = V / (W × L) (1)
[Where V is the wear volume, W is the load, and L is the slip distance]

  From FIG. 2, in Comparative Example 1, separation occurred at a sliding distance of about 600 m, whereas in Example 1 and Comparative Example 2, separation did not occur, and the addition of inorganic particles resulted in a resin. The hardness of the overlay improved with increasing amount of addition.

  Focusing on the difference in particle diameter, it can be seen that in Example 1 and Comparative Example 2, the friction coefficient converges to about 0.06 as the sliding distance increases. Moreover, although the hardness of the resin overlay shows the same value, it turns out that Example 1 which mix | blended nano SiC particle | grains is more effective with respect to specific abrasion loss.

  Further, the aggression attributed to the SiC composition will be considered from the roughness of the mating member (ball surface) after sliding. In Comparative Example 1 where peeling was observed, the resin overlay was not present and the friction between the base member and the mating member became direct, so the values were almost the same. The difference in roughness between Example 1 and Comparative Example 2 in which a resin overlay exists is considered to be due to the difference in dispersed particle diameter. That is, it is suggested that Example 1 having a smaller dispersed particle diameter is less aggressive against the counterpart member.

  As mentioned above, although embodiment of this invention was described in detail for the purpose of illustration, this invention is not restrict | limited to the said embodiment.

DESCRIPTION OF SYMBOLS 10 ... Base material, 20 ... Resin overlay, 30 ... Sliding surface, 100 ... Sliding member

Claims (6)

A substrate made of a metal inorganic nanoparticle material;
A coating layer covering at least a portion of the surface of the substrate;
With
A sliding member that slides relative to the mating member with the portion where the coating layer is formed as a sliding surface,
The sliding member, wherein the coating layer is a thin film containing a resin component, a solid lubricant mixed in the resin component, and inorganic nanoparticles having an average particle diameter in the range of 5 to 300 nm. .   The sliding member according to claim 1, wherein the inorganic nanoparticles are SiC particles.   The sliding member according to claim 1 or 2, wherein the content of the inorganic nanoparticles is in the range of 0.5 to 20% by weight with respect to the entire constituent material of the coating layer.   The sliding member according to any one of claims 1 to 3, wherein the sliding surface forms a bearing raceway surface or a guide surface. It has a coating layer that forms a sliding surface on the surface of a substrate, and is a method for manufacturing a sliding member that slides with a mating member on the sliding surface,
Forming a coating film containing a resin component, a solid lubricant, and inorganic nanoparticles having an average particle size in the range of 5 to 300 nm on the surface of a base material made of a metal material;
Heat-treating the coating film to cure the resin component to form the coating layer;
The manufacturing method of the sliding member characterized by including. The method for manufacturing a sliding member according to claim 5, wherein a spin coating method is used in the step of forming the coating film.

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