JP2015226926A - Slide member production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a slide member which forms a low hardness carbon transfer layer which is tightly fastened, and improves slide characteristics for a long period even after extinction of a periodic structure and a production method of such a slide member.SOLUTION: A grating-shaped irregular periodic structure, whose salient part apex is a non-flat surface and height is varied continuously, is formed on a slide surface of a first member. An amorphous carbon film which is finished by mirror finish is formed on a slide surface of a second member. The slide surfaces of the first and second members are relatively slid, for wearing the periodic structure of the first member as a sacrifice layer.

Description

  The present invention relates to a sliding member and a method for manufacturing the sliding member.

  Diamond-like carbon (DLC) films exhibit excellent tribological properties. For this reason, it has been attracting attention in various fields. It has been suggested that the transfer film caused by the wear powder contributes to lower friction in sliding between the DLC film and the steel material. In the transfer film showing low friction, DLC-derived graphitized carbon is generated on the outermost surface, and the low hardness carbon transfer product is considered to be a factor of low friction.

  It has been reported that when an oxygen plasma treatment is performed on a Si-DLC film to which silicon is added, silicon oxide serves as a binder for fixing the carbon transfer material and lowers the friction. As described above, in order to realize low friction, the adhesion of the transfer film is important along with the generation of low hardness carbon.

  On the other hand, when a grating-like periodic structure having a submicron periodic pitch and groove depth is applied to the steel sliding surface, fine wear powder of the DLC film and the steel is generated. As a result, a smooth and firm carbon transfer film similar to a mild wear surface is formed on the steel material side, and an effect of reducing friction can be expected.

  In order to improve the friction characteristics of the DLC film, the irradiated area is modified to glassy carbon by irradiating the DLC film formed on the sliding surface of the substrate with a femtosecond laser or the like. In the past, a sliding material (sliding member) that has been formed has been proposed (Patent Document 1).

  Conventionally, a sliding member is manufactured by a process of forming an amorphous carbon film containing hydrogen on the surface of a substrate and a process of irradiating the surface of the amorphous carbon film with ultraviolet rays. There is also a thing (patent document 2).

JP2011-168845A JP 2010-215950 A

  In the above-mentioned Patent Document 1, after the DLC layer is formed, the surface of the DLC layer is irradiated with laser. In Patent Document 2, after the DLC layer is formed, the surface of the DLC layer is irradiated with ultraviolet rays. To do. For this reason, DLC is graphitized by laser irradiation or the like, and the original physical properties of DLC are impaired. Further, if the modified layer disappears after long-term use, the function as the sliding member is impaired.

  In view of the above problems, the present invention provides a sliding member that forms a firmly bonded low-hardness carbon transfer layer, and whose sliding characteristics are improved over a long period of time after the periodic structure disappears, and such a sliding member. A method for manufacturing a moving member is provided.

  The method for manufacturing a sliding member according to the present invention includes forming a periodic structure of a grating-like unevenness in which the height of a convex portion is a non-flat surface and the height continuously changes on the sliding surface of the first member. A step of forming a mirror-finished amorphous carbon film on the sliding surface of the second member, and the sliding surface of the first member relative to the sliding surface of the second member. And a wear process in which the periodic structure of the first member is worn as a sacrificial layer.

  According to the manufacturing method of the sliding member of the present invention, since the periodic structure of the grating-like irregularities whose height continuously changes is provided in the first member, the tip of the periodic structure having a small curvature radius is worn when sliding. And familiarity progresses. At this time, fine wear powder such as mild wear powder is generated from the first member. Further, the periodic structure acts as a precise processing tool, and further smoothing of the DLC film proceeds while generating extremely fine wear powder from the amorphous carbon film (DLC film) of the second member. The extremely fine wear powder of the DLC film is graphitized, and low hardness carbon that is important for realizing low friction is generated. At this time, the periodic structure contributes to the suppression of the growth of transfer particles by trapping the wear powder. At this stage, no significant friction reduction effect can be obtained, but in the process of wearing the periodic structure as a sacrificial layer, fine wear powder is crushed and a firmly fixed low hardness carbon transfer layer is formed. At the same time, the first member and the second member are smoothed.

  It is preferable to orient the periodic structure of the grating-like irregularities in the sliding direction. The action of restraining the wear powder in the sliding surface is increased, and the wear powder scattered around the slide mark is greatly reduced.

  It is preferable that at least the sliding surface of the first member is made of a material that generates oxide abrasion powder in the wear process. The first member is a material that generates oxide wear powder in the process of rubbing the periodic structure, so that fine wear powder rich in oxygen is crushed and the wear rate is 1/10 to 10-10 that of severe wear. A transfer layer such as a mild wear surface of 1/1000 can be formed.

  The periodic structure formed in advance on the substrate surface of the first member is formed in a self-organized manner by irradiating a linearly polarized laser beam with an irradiation intensity in the vicinity of the processing threshold value and scanning while overlapping the irradiated portions. It is preferable.

  The sliding member is a sliding member manufactured by using the above-described manufacturing method of the sliding member, and has a periodic structure of grating-like irregularities in which the height of the convex portion becomes a non-flat surface and the height continuously changes. It is preferable that the irregularities of the periodic structure have 50 nm or more and 500 nm or less and the periodic pitch is 10 μm or less.

  In the present invention, in the step of wearing the periodic structure as a sacrificial layer, fine wear powder is crushed to form a firmly fixed low-hardness carbon transfer layer, and the first member and the second member are smooth. As a result, a sliding member having improved sliding characteristics over a long period of time after the periodic structure has disappeared can be obtained.

  When the periodic structure of the grating-like irregularities is oriented in the sliding direction, the amount of wear powder that dissipates around the slide marks is greatly reduced, so that the fine wear powder taken into the sliding surface is crushed and firm. A low-hardness carbon transfer layer fixed to the substrate is efficiently formed.

  If at least the sliding surface of the first member is a material that generates oxide wear powder in the wear process, a transfer layer such as a mild wear surface having a wear rate of 1/10 to 1/1000 of severe wear. Can be formed. The transfer layer such as the mild wear surface acts as a binder that firmly fixes the carbon transfer product to the pin, and contributes to the improvement of the sliding characteristics.

  When a linearly polarized laser beam is irradiated with an irradiation intensity in the vicinity of the processing threshold and the irradiated part is overlapped and scanned to form a self-organized structure, it is difficult to machine with a submicron periodic pitch and uneven depth. A periodic structure having a thickness can be obtained easily.

The first member having the periodic structure of the grating-like irregularities has an irregularity of 50 nm or more and 500 nm or less and a periodic pitch of 10 μm or less, which is similar to a mild wear surface by promoting the generation of low hardness carbon and suppressing the growth of transfer particles. A transfer layer can be formed.

It is a simplified block diagram which shows the process of the manufacturing method of the sliding member which shows embodiment of this invention. It is a simple block which shows a film formation process. It is a perspective view of the manufacturing method of the sliding member which shows embodiment of this invention. The sliding surface of a 1st member is shown, (a) is an enlarged plan view of a periodic structure, (b) is a cross-sectional profile figure of a periodic structure. It is a simplified diagram of the laser surface processing apparatus used for the periodic structure forming method. It is a graph for demonstrating the definition of arithmetic mean roughness. It is a graph which shows the relationship between the frequency | count of a reciprocation when a periodic structure of a 1st member is reciprocated with respect to the mirror surface finish amorphous carbon film of a 2nd member, and a friction coefficient. The sliding trace of the SUJ2 ball reciprocated 10,000 times on the optical mirror surface DLC is shown, (a) is a photograph of the unprocessed SUJ2 ball, and (b) is the SUJ2 ball with the periodic structure formed in a direction parallel to the periodic structure. FIG. 4C is a photographic diagram when sliding, and FIG. 5C is a photographic diagram when a SUJ2 ball on which a periodic structure is formed is slid in a direction orthogonal to the periodic structure. The abrasion powder around the sliding trace on the optical mirror surface DLC is shown, (a) is a photograph when an unprocessed SUJ2 ball is slid, and (b) is a SUJ2 ball with a periodic structure formed as a periodic structure. It is a photograph figure when it slides in a parallel direction, (c) is a photograph figure when a SUJ2 ball in which a periodic structure is formed is slid in a direction orthogonal to the periodic structure. The sliding surface of the 2nd member of the state which made the 1st member reciprocate 10,000 is shown, (a) is a photograph figure, a magnified photograph figure, and a cross-sectional profile figure when sliding an unprocessed SUJ2 bow, b) A photographic view, an enlarged photographic view, and a cross-sectional profile view of a SUJ2 ball with a periodic structure slid in a direction parallel to the periodic structure. (c) is a SUJ2 ball with a periodic structure formed. FIG. 5 is a photographic view, an enlarged photographic view, and a cross-sectional profile view when the slidable member is slid in a direction orthogonal to the periodic structure.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  FIG. 1 is a block diagram showing a method for manufacturing a sliding member according to the present invention, and this manufacturing method includes a periodic structure forming step P1, a film forming step P2, and a wear step P3. In the periodic structure forming step P1, as shown in FIGS. 3 and 4, the periodic structure 3 having grating-like irregularities is formed on the sliding surface 1a of the first member 1, and the film forming step P2 is shown in FIG. As shown, a polishing step P2a for mirror-finishing the sliding surface 2a (see FIG. 3) of the second member 2 and a film-forming step for forming a diamond-like carbon (DLC) film 4 on the mirror-finished surface. P2b. In the wear process P3, the sliding surface 1a of the first member 1 and the sliding surface 2a of the second member 2 are relatively slid to wear the periodic structure 3 as a sacrificial layer.

  The 1st member 1 in the example was comprised with the spherical body, and the 2nd member 2 was comprised with the flat plate body. The first member 1 is made of metal such as SUJ2 (high carbon chromium bearing steel), and the second member 2 is made of metal such as SUS440C (martensitic stainless steel).

  As shown in FIG. 5, the periodic structure forming process P <b> 1 is formed using a laser surface processing apparatus including a laser generator 11 and an optical system 10. In this laser surface processing apparatus, the laser generator 11 is folded back toward the processing material W by the mirror 12 and guided to the mechanical shutter 13. At the time of laser irradiation, the mechanical shutter 13 is opened, the laser irradiation intensity can be adjusted by the half-wave plate 14 and the polarization beam splitter 16, the polarization direction is adjusted by the half-wave plate 15, and the condenser lens 17 The surface of the work material W on the XYθ stage 19 is focused and irradiated.

  In the periodic structure forming step P1, linearly polarized laser is irradiated with an irradiation intensity in the vicinity of the processing threshold, and the irradiated portions are scanned while being overlapped to form in a self-organized manner. That is, when a workpiece (working material) W is irradiated with a linearly polarized laser beam at a fluence near the ablation threshold, interference between the incident light and the scattered light or plasma wave along the surface of the processing material W is approximately the same as the laser wavelength. At periodic intervals, a slight roughness occurs in the energy distribution. In a general processing method, the entire laser irradiation surface is processed, but a high energy portion can be selectively processed by laser irradiation at an energy density near the processing threshold. As a result, a grating-like periodic structure is formed while performing laser irradiation with one optical axis. At this time, the longer the pulse width of the laser used for processing, the more disturbed the periodic structure is due to the influence of heat and the scattering of the laser due to the interaction with the processed evaporation.

  As the mirror finish, polishing (optical polishing) is performed to finish the optically functional surface with less scattering of the surface and variations in local refraction with respect to light. In this case, the arithmetic average roughness Ra is preferably 10 nm or less. This polishing process P2a can be performed by a known publicly known existing polishing apparatus, and various polishing apparatuses are selected according to the material and shape used by the second member 2 and the target arithmetic average roughness Ra. be able to.

As shown in FIG. 6, the arithmetic average roughness Ra is obtained by extracting only the reference length from the roughness curve in the direction of the average line, and setting the X axis in the direction of the average line m of the extracted portion in the direction of the vertical magnification. When the Y-axis is taken and the roughness curve is expressed by y = f (x), the value obtained by the following equation 1 is expressed in micrometers (μm).

  The grating-like irregular structure 3 has a continuously changing height. It is preferable that the height difference of the unevenness of the periodic structure 3 (height from the bottom of the concave portion 5 to the top of the convex portion 6) be 50 nm or more and 500 nm or less. Moreover, it is preferable that the periodic pitch of the periodic structure 3 is 10 μm or less.

  The film forming process P2b is DLC coating, and for example, a plasma ion implantation method can be adopted. The plasma ion implantation method is a method of forming a film by ionization vapor deposition which is a plasma process in a high vacuum. In other words, toluene gas or other hydrocarbon gas is introduced into the vacuum chamber, and radicals in which hydrocarbon ions are excited in DC arc discharge plasma are generated. For this reason, hydrocarbon ions collide with a substrate (a member to be coated) biased to a negative DC voltage with energy corresponding to the bias voltage to solidify into a film. The thickness of the amorphous carbon film (DLC film) 4 formed in the film forming process P2b is about 1 μm.

  In the wear process P3, if the sliding surface 1a of the first member 1 and the sliding surface 2a of the second member 2 are relatively slid, the periodic structure 3 of the grating-like irregularities whose height continuously changes. Is provided on the first member 1, the tip of the periodic structure 3 having a small radius of curvature is worn during sliding, and the familiarity proceeds. At this time, fine wear powder such as mild wear powder is generated from the first member 1. Further, the periodic structure 3 acts as a precise processing tool, and further smoothing of the DLC film 4 proceeds while generating extremely fine wear powder from the amorphous carbon film (DLC film) 4 of the second member. The extremely fine wear powder of the DLC film 4 is graphitized, and low-hardness carbon important for realizing low friction is generated. At this time, the periodic structure 3 contributes to the growth suppression of the transfer particles by trapping the wear powder. At this stage, a remarkable friction reducing effect is not obtained, but in the process of wearing the periodic structure 3 as a sacrificial layer, a fine wear powder is crushed and a firmly fixed low hardness carbon transfer layer is formed. When the first member 1 and the second member 2 are smoothed as they are formed, a sliding member having improved sliding characteristics over a long period of time after the periodic structure 3 disappears can be obtained.

  Since the periodic structure 3 of the grating-like irregularities is oriented along the sliding direction, the action of restraining the abrasion powder in the sliding surface is increased, and the abrasion powder dissipated around the sliding trace is greatly reduced. . As a result, the fine wear powder taken into the sliding surface is crushed and a low hardness carbon transfer layer firmly fixed is efficiently formed.

  The first member 1 is made of a material that generates oxide wear powder in the process of abrasion of the periodic structure 3, so that fine wear powder rich in oxygen is crushed and the wear rate is 1 / of that of severe wear. A transfer layer such as a mild wear surface of 10 to 1/1000 can be formed. The transfer layer such as the mild wear surface acts as a binder that firmly fixes the carbon transfer product to the pin, and contributes to the improvement of the sliding characteristics.

  By irradiating a linearly polarized laser beam with an irradiation intensity in the vicinity of the processing value, scanning the overlapping part, and forming it in a self-organized manner, it is difficult to machine with a submicron periodic pitch and uneven depth. A periodic structure having a thickness can be obtained easily.

  The unevenness of the first member 1 having the periodic structure 3 of the grating-like irregularities is 50 nm or more and 500 nm or less and the periodic pitch is 10 μm or less. Similar transfer layers can be formed.

  As described above, the embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, in the above-described embodiment, the first member 1 is configured by a sphere. Although the 2nd member 2 was comprised by the flat body, it can comprise with the thing of not only the thing of an example of a figure but the shape of the 1st member 1 and the 2nd member 2 with a various other shape.

  As a laser used for the periodic structure forming step, a pulse laser such as a femtosecond laser, a picosecond laser, and a nanosecond laser can be used. Further, in the wear process P3, even if the first member 1 side is fixed and the second member 2 is slid with respect to the first member 1, conversely, the second member 2 side is fixed and the first member 1 is fixed. The first member 1 and the second member 2 may be slid with respect to the second member 2.

In addition, the sliding direction may be parallel or orthogonal to the orientation direction of the periodic structure 3, and may be inclined at a predetermined angle (for example, about 45 degrees). Also good. Further, the sliding direction is not linear but may be circular or elliptical. The load during sliding, sliding stroke, reciprocating frequency, etc. can be arbitrarily set.

  By the way, in the processing of DLC coating, there are a plasma technique using a chemical vapor deposition (CVD) method and a physical vapor deposition (PVD) method. Therefore, in the present invention, the amorphous carbon film can be formed by various conventional methods such as plasma CVD, ionized vapor deposition, sputtering, and arc ion plating.

  The periodic structure 3 was formed on the steel material side, and the influence on the friction coefficient of the optical mirror surface DLC was verified. For this verification, a reciprocating ball-on-plate tester was used. A plate test piece in which an aC: H DLC film is formed by plasma ion implantation is formed on an optically polished SUS440c substrate (Ra 2 nm), and this plate test piece constitutes the second member 2 of the present invention. In this case, the film thickness of DLC was 1 μm. Moreover, this plate test piece is called optical mirror surface DLC. As the first member 1, a SUJ2 ball (Ra 8 nm) ball test piece having a diameter of 6.35 mm was used. The ball specimen was irradiated with a femtosecond laser at an energy density near the processing threshold to form a grating-like periodic structure (pitch: about 700 nm, depth: about 200 nm).

  The sliding directions were two directions orthogonal and parallel to the orientation direction of the periodic structure. What was reciprocated along the orthogonal direction is called periodic orthogonal SUJ2, and what was reciprocated along the parallel direction is called periodic parallel SUJ2. In this verification, an unprocessed ball specimen was also used for comparison. This raw ball specimen is referred to as raw SUJ2. The sliding conditions were a load of 5 N, a stroke of 20 mm, a reciprocation frequency of 0.5 Hz, and the sliding resistance up to 10,000 reciprocations was measured with a load cell. The lubrication conditions were no lubrication.

  FIG. 7 shows the friction coefficients of various SUJ2 balls without lubrication. After 3000 round trips, the periodic parallel SUJ2 has a remarkable friction reduction effect exceeding 30% with respect to the unprocessed SUJ2. On the other hand, the friction coefficient of the periodic orthogonal SUJ2 agreed very well with the period parallel SUJ2 until 3000 reciprocations, but increased monotonically after 5000 reciprocations, and exceeded the friction coefficient of unprocessed SUJ2 after 10,000 reciprocations.

  FIG. 8 shows slide trace photographs of various SUJ2 balls reciprocated 10,000 times on the optical mirror surface DLC. A clear transfer film was observed on the center line in the sliding direction of the periodic parallel SUJ2 in which the friction reduction effect was obtained. The state of the wear powder around the DLC film sliding traces slid with various SUJ2 balls is shown in FIG.

  In the unprocessed SUJ2, transfer particles grew and a large amount of wear powder was generated. On the other hand, in the SUJ2 ball (periodic parallel SUJ2 and periodic orthogonal SUJ2) in which the periodic structure 3 was formed, the wear powder was refined and the amount of wear was reduced. In particular, in the case of periodic parallel SUJ2, the wear powder was greatly reduced. The periodic structure is thought to have contributed to the refinement of the wear powder by trapping the wear powder and suppressing the growth of transfer particles. The periodic parallel SUJ2 has a large effect of restraining the wear powder in the sliding surface, and therefore, it is considered that the wear powder dissipated around the sliding trace is greatly reduced. That is, the wear powder is constrained in the sliding surface and contributes to the formation of a strong transfer film. As a result of EDX (energy dispersive X-ray spectroscopy) analysis, the wear powder was mainly composed of metal oxide derived from SUJ2 balls. The fine wear powder showed a higher oxygen content.

  When the transfer film was observed by SEM (scanning electron microscope), the transfer film had a two-layer structure, the first layer was a mixture of metal oxide (SUJ2 ball wear powder) and carbon, and the second layer was It was a carbon transfer product derived from DLC. Further, the first layer of the transfer film firmly adhered showed a high oxygen content. Therefore, it is considered that the first layer having a high oxygen content functions as a binder that firmly fixes the carbon transfer product to the SUJ2 ball. The low friction of the periodic parallel SUJ2 is thought to be mainly due to the formation of a smooth and firmly adhered carbon transfer film that resembles a mild wear surface by crushing fine wear powder rich in oxygen. It is done. It is considered that the friction coefficient increased after 5000 reciprocations because the periodic orthogonal SUJ2 lacked fine oxygen-rich wear powder acting as a binder and the adhesion of the transfer film was weak.

  FIG. 10 shows a sliding surface of the optical mirror surface DLC. It can be seen that a large amount of wear product is generated around the unprocessed SUJ2, a small amount of wear product is generated around the periodic parallel SUJ2, and a medium amount of wear product is generated around the periodic orthogonal SUJ2.

  As described above, as a result of evaluating the influence of the texture of the counterpart material on the friction coefficient of the DLC film, the periodic structure parallel to the sliding direction forms a transfer film that is firmly fixed under no lubrication, and has a friction reducing effect. can get.

DESCRIPTION OF SYMBOLS 1 1st member 1a Sliding surface 2 2nd member 2a Sliding surface 3 Periodic structure 4 Amorphous carbon film P1 Periodic structure formation process P2 Film formation process P3 Wear process

The present invention relates to a manufacturing method of the sliding member.

The present invention is, in view of the above problems, a manufacturing method of firmly anchored to form a low hardness carbon transfer adhesive layer, after the periodic structure is extinguished even you improved sliding characteristics over a prolonged sliding member provide.

The method for manufacturing a sliding member according to the present invention includes forming a periodic structure of a grating-like unevenness in which the height of a convex portion is a non-flat surface and the height continuously changes on the sliding surface of the first member. A step of forming a mirror-finished amorphous carbon film on the sliding surface of the second member, and the sliding surface of the first member relative to the sliding surface of the second member. by moving, by Rukoto abrading the periodic structure of the first member as the sacrificial layer has a first layer containing wear debris from the first member, and a second layer of carbon transferred materials from the second member it is obtained by a wear process you forming a transfer film deposition of a two-layer structure.

Claims (5)

A periodic structure forming step of forming a periodic structure of grating-like irregularities in which the height of the convex portion is a non-flat surface and the height continuously changes on the sliding surface of the first member;
A film forming step of forming a mirror-finished amorphous carbon film on the sliding surface of the second member;
A sliding step characterized by comprising a wear process in which the sliding surface of the first member and the sliding surface of the second member are relatively slid to wear the periodic structure of the first member as a sacrificial layer. Manufacturing method of member.   The method for manufacturing a sliding member according to claim 1, wherein the periodic structure of the grating-like irregularities is oriented in the sliding direction.   The method for manufacturing a sliding member according to claim 1, wherein at least a sliding surface of the first member is made of a material that generates oxide abrasion powder in the wear process.   The periodic structure formed in advance on the substrate surface of the first member is formed in a self-organized manner by irradiating a linearly polarized laser beam with an irradiation intensity in the vicinity of the processing threshold and scanning while overlapping the irradiated portions. The manufacturing method of the sliding member in any one of Claims 1-3 characterized by the above-mentioned. A sliding member manufactured using the manufacturing method of the sliding member according to any one of claims 1 to 4,
Sliding characterized in that the irregularities of the periodic structure having a grating-like irregularity structure in which the height of the convex part is a non-flat surface and the height continuously changes are 50 nm to 500 nm and the periodic pitch is 10 μm or less Element.