JP2003004043A - Anticorrosive sliding member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anticorrosive sliding member capable of ensuring the performance of lubrication, anticorrosion and anti-seizure of a sliding face of an uneven pattern for a long period. SOLUTION: In an sliding member that supports the rotating or swinging object applied to a plain bearing, an inside outer ring race face of rolling bearing and a contact part of thrust receiving part or an artificial joint of groove bearing, an uneven pattern is formed to the sliding face of base metal with 0.8 to 1.6 mm arrangement pitch of recessed or convex part and 1 μm to 10 μm depth on 30 to 70% of whole sliding face. Furthermore the anticorrosive sliding member filled by solid lubrication film in the recessed part of this hard film surface is provided, arranging the hard film of TiN, TiC, TiB2 , etc., or the hard film by ion implantation with the thickness capable of maintaining the uneven face of the uneven pattern along with the formation of the uneven pattern of the base metal.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding member in which a sliding surface of a member in sliding contact has been subjected to abrasion resistance and low friction resistance treatment. In particular, the present invention is applied to sliding parts such as plain bearings used in vacuum, inner and outer race surfaces of rolling bearings, thrust receiving parts of groove bearings, and artificial joints, in addition to general mechanical parts that make relative sliding contact. The present invention relates to a sliding surface structure of a wear-resistant sliding member useful as a sliding member. 2. Description of the Related Art Japanese Patent Application Laid-Open No. Sho 60-1355 discloses that a sliding surface of a member that makes relative sliding contact is subjected to a wear-resistant treatment.
There is a metal sliding member disclosed in JP-A-64. This is because the wear-resistant hard material and the solid lubricant are separated and sputter-deposited on the sliding surface of at least one of the metal members that are in sliding contact with each other, thereby forming the hard material deposition portion and the solid lubrication material deposition portion. In the form of a mottled or dimple-shaped pattern (hereinafter referred to as a mottled pattern). With this configuration, a load is applied to the hard material portion that comes into sliding contact, the surrounding solid lubricating material is dug out by sliding contact with the mating member, and is supplied to the hard material portion as a lubricant, and wear resistance is improved. At the same time, a reduction in frictional force is provided. As another example, an uneven surface can be formed on the surface of a base material of a sliding member, and a solid lubricating film can be formed directly on the uneven surface, or the uneven shape can be maintained on the uneven surface. After providing the hard material layer in the range, a solid lubricating film is formed on the uppermost layer so as to cover the entire uneven surface, thereby preventing peeling of the solid lubricating film due to shear stress during sliding, as well as abrasion resistance and A wear-resistant sliding member capable of exhibiting sufficient lubrication has been proposed (JP-A-2-76).
925). [0004] In any of the above-mentioned conventional metal sliding members or wear-resistant sliding members, the lubricant from the solid lubricated surface is accompanied by the wear resistance around the sliding member. High lubricity is obtained because it is supplied to the convex part of the sliding surface of the hard material or base material, and the load is applied to the convex part of the wear-resistant hard material or the concave and convex pattern, so that the load capacity and dimensional accuracy are improved. There is an effect to get. However, in the above-mentioned Japanese Patent Application Laid-Open No. 60-135564, the area ratio of the two material portions of the mottled pattern formed by the hard material portion and the solid lubrication material portion on the sliding surface is appropriately tested depending on the use conditions of each member. It is merely specified, but not specified. JP-A-2-76925 also exemplifies the diameter of each cylindrical or cylindrical concave or convex portion. However, the number or distribution of the concave or convex portions, that is, the area ratio of the concave or convex portion occupying the entire sliding surface is described. Is not shown. In the sliding member having the uneven pattern as described above, a load is applied to the convex portion and the lubricant is supplied from the concave portion. On the contrary, if the area of the entire convex portion is large, that is, if the concave portion is small, the ability to supply the lubricant decreases. Regarding the depth of the concave portion, if the depth of the concave groove is large, the lubricant from the concave portion is difficult to flow to the convex portion, and if the concave portion is too shallow, the lubricant cannot be effectively held. In order to maximize the low frictional resistance and wear resistance of the sliding member, it is necessary to set the area ratio between the concave portion and the convex portion of the concave-convex pattern and the groove depth of the concave portion to optimal values. . According to the present invention, the area ratio of the concave and convex portions and the depth of the concave portions on the sliding surface on which the concave and convex pattern is formed, and the arrangement pitch of the concave and convex portions are set in optimum ranges, and a hard layer is provided on the sliding surface. By providing an uneven portion on the surface of the hard layer and filling the concave portion with a solid lubricant, a sliding member capable of ensuring lubrication, abrasion resistance, and seizure resistance of the sliding surface for a long period of time is provided. It is in. According to the present invention, the present invention is applied to a race bearing, a race surface of an inner / outer ring of a rolling bearing, a thrust receiving portion of a groove bearing or a contact portion of an artificial joint to rotate or swing. In the sliding member supporting the object, the arrangement pitch of the concave portions or the convex portions on the sliding surface of the base material is 0.8 to 1.6.
mm, an area ratio of the concave portion is 30 to 70% of the entire sliding surface, and a depth is 1 μm or more and 10 μm or more.
m or less, and a hard film of TiN, TiC, TiB ₂ or the like or a hard film formed by ion implantation is provided with a thickness capable of maintaining the uneven surface of the uneven pattern while forming the uneven pattern of the base material. A wear-resistant sliding member in which a concave-convex pattern is formed on a sliding surface of a base material that is in sliding contact with another member filled with a solid lubricant film in a concave portion, and a concave portion of the concave-convex pattern is filled with a solid lubricant. You. According to one embodiment of the present invention, the convex / concave pattern having a cylindrical convex portion or the concave pattern having a cylindrical concave portion is one of the relative sliding surfaces of the artificial hip joint (artificial head or acetabular socket). Alternatively, there is provided an artificial hip joint structure in which these cylindrical convex portions or cylindrical concave portions have a diameter of about 0.5 mm and a pitch of about 1.2 mm. The area ratio of the concave portion on the surface of the base material of the sliding member is 30 to
In a sliding member having a concave / convex surface of preferably 70%, a concave depth of 1 mm or less or preferably 10 μm or less in order to shorten the processing time, the lubricant is restrained by the concave / convex surface of the base and the concave portion supplies the lubricant. The lubrication of the sliding surface can be maintained for a long period of time because the convex portion has a load. In addition, a hard material layer is provided on the surface to the extent that the uneven surface can be maintained, and the concave portion on the upper surface of the hard layer is filled with a solid lubricant, so that the hard material layer functions as a wear barrier, and has higher wear resistance and seizure resistance. Property is obtained. Further, even if abrasion occurs in the sliding portion, the abrasion powder can escape to the concave portion, and rapid wear due to abrasive can be prevented. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. 1 and 2 are partial perspective views of a sliding surface of a wear-resistant sliding member according to various embodiments of the present invention. As the base material 1, various industrial materials such as iron, carbon steel, stainless steel and other non-ferrous metals, copper, aluminum and other non-ferrous metals, or non-metals such as ceramics and ultrahigh molecular weight polyethylene are used. In the example shown in FIG. 1, a plurality of columnar projections 2 are regularly formed on the sliding surface of the base material 1 at regular intervals, and portions other than the projections 2 are recesses 3. The moving surface has these convex portions 2
And a concave / convex pattern formed by the concave portions 3. The diameter of the convex portion 2 is D, if the number of the N, sliding contact area of the projection 2 of the entire sliding surface is πND ^2/4, the remainder of the area of this area with respect to the entire sliding surface Thus, the concave portions are formed at a ratio of 30 to 70%. In the case of FIG. 2, a plurality of cylindrical recesses 3 having a diameter D are regularly formed on the sliding surface of the base material 1 at regular intervals, and portions other than these recesses 3 are projected on the sliding surface. Part 2 2, the area ratio of the entire concave portion 3 to the sliding surface is 30 to 70%. The concavo-convex pattern is not necessarily limited to the columnar or cylindrical shape as described above, but may be a rectangular or other polygonal concavo-convex portion, or a pattern in which concave portions and convex portions are divided into layers and arranged. And so on. Each of them is regularly arranged on the entire sliding surface, and the area ratio of the entire concave portion is 30 to 70% with respect to the entire sliding surface. The basis for setting the ratio of the convex portion 2 or the concave portion 3 as described above will be described with reference to a specific wear friction test. First, FIG. 3 shows a friction and wear test apparatus employed in the present invention. A spherical contact 6 is fixed to the lower end of the rotating shaft 4 vertically supported by the air bearing 5 eccentrically from its axis,
The sample 8 attached to the sample mounting table 7 is
Are in contact. Note that a load is applied to the rotating shaft 4 and the sample mounting table 7 in the axial direction, so that the pressure contact force between the contact 6 and the sample 8 can be adjusted. The sample mount 7 is supported by an air bearing 9 in the thrust direction and the radial direction. The outside of the sample mount 7 is a fixed load cell 1
The contact 6 and the sample 8 are driven by rotating the rotating shaft 4 around the axis with a variable speed motor (not shown).
The load in the rotation direction of the sample mounting table 7 due to the frictional force between the contact 6 and the sample 8 is detected by the load cell 10, and the change over time in the frictional force between the contact 6 and the sample 8 is observed. The time-torque characteristic diagram obtained by this method is generally as shown in FIG. 4, and the life is determined as the time until the torque change suddenly starts increasing (point E). As described above, in the sliding member having the uneven pattern formed thereon, a load is applied to the convex portion, and the lubricant is supplied from the concave portion. When the number of convex portions decreases, the load-bearing performance decreases, and when the number of concave portions decreases, the ability to supply the lubricant decreases. Therefore, there is an optimum area ratio between the convex portion and the concave portion on one sliding surface. If the depth of the concave portion is too large, the lubricant hardly flows to the sliding surface, and if it is too shallow, insufficient lubrication occurs. Therefore, there is an optimum value for the depth h of the concave portion. In the sliding surface on which the convex pattern formed by the columnar convex portions 2 as shown in FIG. 1 was formed, the area ratio of the entire concave portion 3 to the sliding surface was changed, and the concave portion 3 was coated with a MoS ₂ sputtered film as a solid lubricant film. Table 1 shows the test data of the coating life of the samples.
The depth of each of the concave portions was 10 μm. [Table 1] Here, the rotation speed of the rotating shaft 4;
m, contact pressing load; 0.23 kgf, sliding speed;
0.4 m / s. At an area ratio of the recess 3 of 14%, a sudden increase in torque was observed after 2 hours due to insufficient lubrication, and the 80%
If it exceeds, the convex portion 2 is distorted, and the load cannot be received. The pattern type "none" is a case where there is no uneven portion. A concave / convex pattern formed by a cylindrical concave portion 3 as shown in FIG. 2 is formed on the sliding surface, the area ratio of the concave portion 3 is changed, and the MoS ₂ sputtered film is coated thereon as a solid lubricating film. The test data is shown in Table 2. The depth of each of the concave portions was 10 μm. Also in this example, when the area ratio of the concave portion is 14%, the lubrication is insufficient, and when the area ratio is 80%, the load capacity decreases. The sample (shown as “none” in the table) in which the MoS ₂ film was simply sputtered without the concavo-convex pattern had a small load capacity, and the film life was 1 hour. [Table 2] The life of the coating is also related to the depth of the concave portions of the concave / convex pattern. In the wear test using the apparatus shown in FIG. 3, when the wear state of the sliding surface was observed with a roughness meter, the difference in wear due to the presence or absence of a concavo-convex pattern with respect to the sliding surface coated with ultra-high molecular weight polyethylene was measured. Notable. The large scar seen in the result of the roughness meter when the concavo-convex pattern is not provided is considered to be that the sliding surface was deeply shaved by the abrasion powder. That is, the wear powder itself causes new wear. However, on the sliding surface provided with the concavo-convex pattern, in addition to the supply of the lubricant from the concave portion, the escape of the wear powder to the concave portion is caused, and the wear powder does not enter the convex portion of the slide surface. Table 3 shows that the area ratio of the concave portion 3 is set to 70% of the entire sliding surface on the sliding surface provided with the concavo-convex pattern as shown in FIG. 2, and the groove depth h of the concave portion 3 is changed. Test data of film life when a MoS ₂ sputtered film is coated as a lubricating film is shown. [Table 3] According to this data, when the groove depth h exceeds 15 μm, the lubricant accumulates at the bottom of the concave portion 3 and the lubricant does not flow out to the convex portion 2, and the life of the coating film is significantly reduced. In the sliding surface structure according to the present invention, the area ratio of the concave portion of the concave / convex pattern is 30 to 70%, and the groove depth of the concave portion is 10%.
The sliding surface having the concavo-convex pattern in this range is at most 1 μm or less, and it can be seen from the above experimental results that the sliding surface exhibits the maximum low frictional resistance and wear resistance. An application example of the present invention is surface modification of a relative sliding portion of an artificial joint. In artificial joints, the prosthetic head and acetabular socket that fit together generally consist of a combination of metal or ceramics and ultra high molecular weight polyethylene. The test was carried out using ultrahigh molecular weight polyethylene whose contacts were finished in a plane by the abrasion friction test apparatus shown in FIG. 3, and using a stainless steel material coated with TiN having excellent biocompatibility. FIG. 5 shows the change in the frictional force in this case. When a sample without an uneven pattern is used, the fluctuation of the frictional force is large and unstable.
On the other hand, when the sample to which the concavo-convex pattern is added is used, the fluctuation is small and it can be seen that it is stable. It is difficult to judge the difference in wear due to the presence or absence of a pattern on the surface of the sample TiN by observation after the test, but for ultra-high molecular weight polyethylene as a solid lubricant, it is better if no pattern is added. It is observed that abrasion has occurred significantly as compared with the case where the pattern is added. When the roughness was measured without adding a pattern, a large scar was found. It is considered that the scar was deeply shaved by the wear debris. When a pattern is added, abrasion pieces are taken into the concave portions and do not come out on the sliding surface, so that large abrasion is prevented. Similarly, a sample having an uneven pattern formed on the sliding surface was coated with TiN having excellent biocompatibility, and a friction test was performed in physiological saline using ultrahigh molecular weight polyethylene as a mating material. FIG. 6 shows a temporal transition of the frictional force at the time. For comparison, a case where a sample without an uneven pattern was tested under the same conditions is also shown in FIG. This figure also clearly shows the superiority of the sliding surface having the concavo-convex pattern. FIG. 7 is an exploded side view of an artificial hip joint using the wear-resistant sliding surface structure of the present invention. A ball (artificial bone head) 12 is mounted on the tip of the stem 11, and the concave spherical surface 13 a of the acetabular socket 13, which is a mating member, is fitted to the ball 12 so as to be relatively slidable. On one or both of the sliding surfaces of the ball 12 and the socket 13, a concavo-convex pattern is formed by a cylindrical convex portion 2 or a cylindrical concave portion 3 as shown in an enlarged manner in FIG. 1 or FIG. Although the area ratio and the depth of the concave portion 3 of the concave and convex pattern may be in the above ranges, the diameter and the pitch of each convex portion 2 or the concave portion 3 also have an optimum value when used as an artificial hip joint. I do. FIG. 8 is a view showing the experimental results of the sliding surface characteristics of the artificial hip joint with respect to the diameter (mm) of the cylindrical concave portion of the concave-convex pattern. Ultrahigh molecular weight polyethylene was used for the sliding surface. The white circles plotted in the figure indicate the value of the reduction rate (%) of the frictional force with respect to the diameter of the concave portion, and the black circles indicate the wear amount (mm) of the ultrahigh molecular weight polyethylene. FIG. 9 also shows the reduction rate of the frictional force (open circle) with respect to the pitch (mm) of the cylindrical concave portion on the sliding surface of ultrahigh molecular weight polyethylene.
And the experimental results for the wear amount (black circles). As can be seen from these figures, the diameter D of the concave portion is 0.
When the pitch is 5 mm and the pitch p (FIG. 2) is 1.2 mm, the reduction rate of the frictional force is the largest, and the wear amount of the ultrahigh molecular weight polyethylene is the smallest. From the above, in the case of an artificial hip joint having a concavo-convex pattern, a pattern diameter of 0.5 mm and a pitch of 1.2 mm are optimal values for maximizing lubrication characteristics.
Although the improvement of the material alone did not provide a sufficient effect as a means for preventing friction and wear of the artificial joint as in the past, the sliding surface structure as in the present invention provides lubrication of the sliding surface of the artificial joint. The characteristics can be improved and the life of the artificial joint can be greatly extended. In the above description, the depth of the recess is set to 1.0 m.
m or less, preferably 10 μm. For example, the sliding surface used for an artificial hip joint or the like is preferably deep when it is necessary to confine wear powder, and shallow when the solid lubricant is filled in the concave portion. The depth is appropriately selected within the above range. However, from the viewpoint of processing, it is shallow, preferably 10 μm or less, particularly when the concavo-convex pattern needs to be formed by fine processing technology. As described above, according to the present invention, a concavo-convex pattern is formed on the surface of a base material which is in sliding contact with another member, the area ratio of the concave portions is 30 to 70%, and the depth of the concave portions is 30%. 1.0
mm or less to reduce the processing time.
μm or less, under solid lubrication conditions or in a liquid such as physiological saline, the abrasion resistance and seizure resistance can be prevented by supplying lubricant from the recess and preventing abrasive wear due to escape of abrasion powder into the recess. Is improved. Also with the formation of the uneven pattern of the base material, TiN so as to maintain the irregular shape of the uneven pattern, TiC, the hard layer provided by the hard film and ion implantation, such as TiB _2, a solid lubricant in the recess of the hard layer surface By filling, the lubricant flowing out of the concave portion lubricates the convex portion of the hard layer, thereby preventing the wear of the hard layer and receiving a load at the convex portion of the hard layer. Load performance is obtained, and higher wear resistance, seizure resistance and improved load capacity are achieved. In addition, unlike the carburized layer or the carburized boron layer formed by carburizing and quenching or boron carburizing, the hard layer having such a form does not require surface processing after hardening. By applying the present invention to an artificial joint, the characteristics of the joint sliding surface can be improved, particularly friction and wear can be drastically reduced, and the effect of extending the life of the artificial joint can be greatly improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial perspective view of a wear-resistant sliding member having a convex pattern according to an embodiment of the present invention. FIG. 2 is a partial perspective view of a wear-resistant sliding member having a concave pattern according to another embodiment of the present invention. FIG. 3 is a schematic longitudinal sectional view of a wear friction test apparatus according to the present invention. FIG. 4 is a diagram showing time-torque characteristics obtained in a wear friction test. FIG. 5 is a diagram showing a change over time of a frictional force in a frictional force test between an ultrahigh molecular weight polyethylene and a TiN coating material. FIG. 6. Ultra high molecular weight polyethylene and T in saline
FIG. 6 is a diagram showing a change over time of friction force when a friction test with an iN coating material is performed. FIG. 7 is an exploded side view of an artificial hip joint according to an application example of the present invention. FIG. 8 is a graph showing a sliding surface characteristic of an artificial hip joint with respect to a concave portion diameter of a concave-convex pattern on a sliding surface according to the present invention. FIG. 9 is a diagram showing the sliding surface characteristics of the artificial hip joint with respect to the concave pitch of the concave-convex pattern on the sliding surface according to the present invention. [Description of Signs] 1 Base material 2 Convex portion 3 Concave portion 4 Rotating shaft 5, 9 Air bearing 6 Contact 7 Sample mount 8 Sample 10 Load cell 12 Ball 13 Socket

Continuation of front page    (72) Inventor Daijiro Iena             Hokkaido, Sapporo City (72) Inventor Takeshi Saito             1-5-50 Nihonsei, Kugenuma Shinmei, Fujisawa City, Kanagawa Prefecture             Kosaku Fujisawa Plant (72) Inventor Tomita Suzuki             1-5-50 Nihonsei, Kugenuma Shinmei, Fujisawa City, Kanagawa Prefecture             Kosaku Fujisawa Plant (72) Inventor Mamoru Tanaka             1287-6, Rokuura-cho, Kanazawa-ku, Yokohama-shi, Kanagawa F term (reference) 3J011 AA07 BA10 CA05 CA06 DA01                       JA01 KA03 MA03 PA02 QA03                       SB13 SE10                 3J101 AA01 BA53 BA54 BA56 BA70                       CA14 EA02 EA06 EA41 EA78                       FA32 FA33

Claims (1)

Claims: 1. A sliding member for supporting an object that rotates or swings by being applied to inner and outer race surfaces of a sliding bearing, a rolling bearing, a thrust receiving portion of a groove bearing or a contact portion of an artificial joint. A concave / convex pattern in which the arrangement pitch of the concave portions or convex portions is 0.8 to 1.6 mm is formed on the sliding surface of the base material, and the area ratio of the concave portions is 30 to 70% of the entire sliding surface;
The depth is set to 1 μm or more and 10 μm or less, and the formation of the uneven pattern of the base material and the formation of TiN, TiC, TiB
_A wear-resistant sliding member characterized in that a hard film such as ₂ or a hard film formed by ion implantation is provided with a thickness capable of maintaining the uneven surface of the uneven pattern, and a concave portion of the hard film surface is filled with a solid lubricating film. .