JP5934972B2 - Lubricationless sliding member - Google Patents

Description

  The present invention relates to a non-lubricated sliding member, and more particularly, to a non-lubricated sliding member that maintains initial performance even when slid over a long period of time and has little wear.

  A sliding member used in the aircraft field or the like is required to be lightweight and highly durable. As such a sliding member, a non-lubricating sliding member used without lubrication is known.

  As a known non-lubricating sliding member, a non-lubricating sliding member having a polytetrafluoroethylene (hereinafter sometimes abbreviated as PTFE) -based fabric liner is known. This non-lubricating sliding member is a combination of a member in which a PTFE fabric liner is attached to the surface of a base material with a thermosetting adhesive and a counterpart material that is in contact with and faces the PTFE fabric liner surface.

  In a sliding member having a PTFE-based fabric liner, damage such as scratches occurs on the surface of the counterpart material during long-term use. Although the mechanism has not been fully elucidated, if the degree of damage exceeds the allowable range, the PTFE fabric liner itself breaks down and the dynamic friction coefficient increases, causing the torque to become unstable in the spherical bearing, and then the liner itself Due to the progress of wear, it will not function as a sliding member in a short period of time, leading to a lifetime.

  For this reason, selection of a mating material in contact with the PTFE-based fabric liner surface that can achieve a longer life has been an issue. Conventionally, stainless steel, titanium alloys, or those that have been surface-treated are used as such mating materials. It has been.

  In particular, titanium alloys used in various fields such as aerospace, deep sea exploration, and chemical plants have high specific strength and excellent corrosion resistance, and are therefore suitable as counterpart materials that come into contact with PTFE-based fabric liner surfaces. It is considered.

  For example, as an example of using a titanium alloy as such a counterpart material, an external holder having a PTFE-based fabric liner on a concave spherical sliding surface, and an internal holding having a thin film layer of TiAlN compound on the convex spherical sliding surface A spherical bearing made of a tool is disclosed (for example, see Patent Document 1).

  However, even when a titanium alloy coated with a TiAlN compound is used as a counterpart material, it is not always sufficient to withstand damage from a PTFE-based fabric liner for a long period of time for use in the aircraft field or the like.

  Further, as another titanium alloy composite material excellent in specific strength, carbon nanotubes (hereinafter abbreviated as CNT) coated with a layer containing an element such as Si, Cr, Ti, etc. that reacts with carbon to form carbides and the carbides. In other words, a titanium alloy composite material is disclosed in which the titanium alloy composite material is dispersed in the crystal grains of the titanium alloy (see, for example, Patent Document 2).

  Such a titanium alloy composite material can be obtained by fixing CNTs coated with a carbide-containing layer on the surface of the titanium alloy powder, and then heating and sintering the powder to obtain tensile strength, Young's modulus. It is said that mechanical strength such as toughness and hardness is superior to conventional titanium alloys. However, its sliding characteristics are not well known.

JP 2005-30492 A JP 2007-70697 A

  The present invention has been made in view of the above situation, and is a lightweight sliding member having a PTFE-based fabric liner used without lubrication on a sliding surface, and has a frictional resistance when sliding. An object of the present invention is to provide a long-life, non-lubricating sliding member that is less prone to surface scratches due to wear and sliding of PTFE-based fabric liners and that maintains initial performance even when sliding over a long period of time. .

  As a result of intensive research on the sliding characteristics with respect to the PTFE-based fabric liner, the inventors have found that when a titanium alloy composite material in which CNT is added to a β-rich α + β titanium alloy is used as a counterpart material when the PTFE-based fabric liner slides, It showed a low coefficient of dynamic friction and was able to withstand long-term continuous sliding.

That is, the non-lubricated sliding member of the present invention has a pair of sliding surfaces that relatively slide while in contact with each other, one sliding surface being a polytetrafluoroethylene fabric liner, and the other A non-lubricating sliding member having a sliding surface made of a titanium alloy composite material obtained by adding carbon nanotubes to a titanium alloy , wherein the titanium alloy is a β-rich α + β titanium alloy .

  In this invention, it is set as the preferable aspect that the tungsten carbide nanoparticle is further added to the titanium alloy.

In the present invention, the titanium alloy composite material is characterized in that the carbon nanotubes are distributed as fine spherical titanium carbide in the metal structure .

In the present invention, one sliding surface is a sliding surface formed by fixing a polytetrafluoroethylene fabric liner to a cylindrical inner peripheral surface or outer peripheral surface, and the other sliding surface is a cylindrical surface. The outer peripheral surface or the inner peripheral surface is a preferred embodiment.

  In the present invention, the non-lubricated sliding member includes a first member having a concave spherical first sliding surface formed by fixing a polytetrafluoroethylene-based fabric liner to the inner peripheral surface, and the first member. A second member having a convex second spherical sliding surface made of a titanium alloy composite material which is held by the member and capable of relatively sliding while being in contact with the first sliding surface; A preferred embodiment is a non-lubricated spherical plain bearing.

  The titanium alloy of the base material of the composite material of the present invention is lightweight, high strength and excellent in corrosion resistance, and the reaction of CNT and CNT with the base material titanium by a special manufacturing process combining powder metallurgy and hot plastic working methods. The fine titanium carbide spherical particles produced in 1) are dispersed in the matrix, so that excellent mechanical properties are imparted to the material itself. Furthermore, the base material hardness can be increased by an appropriate aging treatment. Further, it is possible to further increase the strength and hardness by adding a small amount of tungsten carbide (WC) or diamond nanoparticles as the second phase particles. Therefore, a sliding member having a light weight and a long life can be obtained by combining with the PTFE-based fabric liner even if the composite material is not subjected to surface hardening treatment.

2 is a schematic diagram showing a test method in Example 1. FIG. It is a graph which shows the abrasion test result in the developed material and comparative material of this invention. It is a graph which shows the abrasion test result in the developed material and comparative material of this invention. It is an optical microscope photograph which shows the sliding surface state of the test piece (CNT titanium alloy composite material) after an abrasion test, (a) is orthogonal to the grinding direction of a disk, (b) is parallel to the grinding direction, (c ) Is a ring. It is an optical microscope photograph which shows the sliding surface state of the test piece (DHA1) after an abrasion test, (a) is orthogonal to the grinding direction of the disk, (b) is parallel to the grinding direction, and (c) is a ring. is there. FIG. 6 is an explanatory diagram of Example 2. It is an electron micrograph showing the dispersion state of spheroidized TiC fine particles.

Hereinafter, preferred embodiments of the present invention will be described in detail.
The non-lubricated sliding member of the present invention has a pair of sliding surfaces that relatively slide while in contact with each other, one sliding surface is a PTFE fabric liner, and the other sliding surface is titanium. It is characterized by being an alloy, preferably a titanium alloy composite material in which CNT is added to a β-rich α + β titanium alloy (hereinafter sometimes abbreviated as CNT-Ti alloy).

  The sliding member of the present invention comprises a combination of a member formed by adhering a PTFE fabric liner to the surface of an arbitrary metal material via a phenol resin and a mating member made of a CNT-Ti alloy. The surface of the liner slides on the surface of the CNT-Ti alloy. If these two members are provided, the present invention can be applied to any sliding part. For example, a combination of an inner ring and an outer ring in a spherical bearing is conceivable.

  The sliding member is a combination of a composite material obtained by adding CNT to the β-rich α + β titanium alloy of the present invention and a PTFE fabric liner, and the raw material is used as it is without being subjected to special surface hardening treatment. This composite material is manufactured by a special process that combines powder metallurgy and plastic working, and has sufficient hardness (~ 53HRC) after heat treatment even though it is a titanium-based material, and without PTFE treatment, etc. It has been found that a very low and stable dynamic friction coefficient (˜0.02) persists over a long period of time for fabric based liners. As a result, the amount of wear is extremely small, high dimensional accuracy can be maintained over a long period of time, and a long life can be achieved.

  In a sliding member having a PTFE fabric liner, the wear of the mating material progresses, and when a certain limit is exceeded, the liner side wears rapidly and reaches the end of its life. For titanium alloys, sufficient hardness cannot be obtained with existing alloys, so carbonitriding treatment and surface coating treatment such as TiAlN are indispensable. , Had problems such as chipping. Since this composite material has sufficient durability as it is, the surface treatment is unnecessary. Further, even when surface treatment is performed in order to further improve durability, the base material has sufficient hardness, and thus compatibility with a hard coating is good.

  The present invention is particularly effective for applications that require weight reduction and maintenance-free as bearings that are used without lubrication in the field of aircraft equipment that requires weight reduction.

Polytetrafluoroethylene-based fabric liner The PTFE- based fabric liner of the present invention is also referred to as a Teflon (registered trademark) liner, and PTFE fibers are blended with a back-up material (reinforcing material) to form a woven fabric (fabric), such as a phenol resin. A liner impregnated with a thermosetting resin. Since it has both a low coefficient of friction and high mechanical strength, it has a high surface pressure under non-lubricated conditions (up to 482 N / mm ² {49.2 kgf / mm ² } under static load, 220 to 275 N / mm ² { 22.5 to 28.1 kgf / mm ² }) and is used for aircraft plain bearings and the like.

  This PTFE-based fabric liner is used by being bonded to a metal surface using a thermosetting adhesive.

  As the backup material, synthetic fibers such as glass fiber, polyester fiber (trade name: Dacron: DuPont), polyamide fiber (trade name: Nomex: DuPont) can be used.

Titanium alloy composite material Among the sliding members of the present invention, the member that slides in contact with the PTFE fabric liner is a titanium alloy composite material obtained by adding CNT to a titanium alloy, and this composite material reacts with carbon. Thus, an element that generates carbide and CNT covered with a layer containing the carbide are dispersed in the crystal grains of the titanium alloy. That is, the layer covering the CNTs is composed of carbides generated by the reaction of the above elements with a part of the CNTs, and unreacted elements. And since this layer functions as a layer that suppresses the reaction between CNT and titanium at the time of compounding and enhances the wettability with the titanium alloy, the performance as a reinforcing material possessed by CNT is maintained even after compounding. ing. Furthermore, in the present invention, the mechanical strength such as tensile strength, Young's modulus, toughness, and hardness can be remarkably improved by dispersing the coated CNTs in the crystal grains. In the present invention, the state in which the CNTs are dispersed in the crystal grains of the titanium alloy means that at least a part of the CNTs has an appropriate dispersibility in the microcrystal grains of the titanium alloy due to plastic flow during plastic processing. The state of being captured while keeping.

  The CNTs in the present invention are not particularly limited in fiber diameter, fiber length, shape, etc., and conventionally known CNTs generally used as reinforcing materials can be used without limitation. Examples of CNTs include single-walled CNTs and multilayered CNTs produced by vapor deposition, arc discharge, laser evaporation, and the like. From the viewpoint of further improving the performance as a reinforcing material and the dispersibility in the titanium alloy, the fiber diameter of the carbon nanotube is preferably 2 nm to 80 nm and the fiber length is preferably 1 μm to 100 μm. In addition, the fiber diameter, fiber length, and shape of CNT in the titanium composite material can be measured by microstructure observation with an ultrahigh resolution FE-SEM or a transmission electron microscope.

  Further, the content of CNT is preferably 0.1% by mass to 10% by mass, more preferably 0.2% by mass to 5.0% by mass, and most preferably 0% with respect to the titanium alloy composite material. .4 mass% to 3.0 mass%. If the content of CNT is within the above range, the mechanical properties can be further improved. In addition, the content of CNT in the titanium composite material is analyzed by morphological observation and elemental analysis using an ultra-high resolution FE-SEM or a transmission electron microscope and analysis according to “JIS H 1617 carbon determination method in titanium and titanium alloy”. Can be measured.

  In the present invention, the element that coats the CNT is not particularly limited as long as it reacts with carbon to produce a carbide, but from the group consisting of silicon, chromium, titanium, vanadium, tantalum, molybdenum, zirconium, boron, and calcium. It is preferably at least one selected, and more preferably at least one selected from silicon and chromium. The elements exemplified above can further improve the mechanical properties because the carbides are excellent in affinity with the titanium alloy.

  Further, the thickness of the layer containing the above element and its carbide covering CNT is preferably at least 0.5 nm, more preferably from the viewpoint of further improving the mechanical strength by dispersion strengthening in the titanium alloy. It is preferably 2 nm to 50 nm, and particularly preferably 0.5 nm to 10 nm. Note that it is possible to confirm whether or not the CNT is covered with a layer containing the above element and its carbide by observing the structure with an ultrahigh resolution FE-SEM or a transmission electron microscope.

Next, the manufacturing method of the titanium alloy composite material of this invention is demonstrated.
The method for producing a titanium alloy composite material according to the present invention includes a CNT coating step of coating CNTs with an element that reacts with carbon to generate carbides and a layer containing the carbides, and CNT fixation for fixing CNTs on the surface of the titanium alloy powder And a CNT dispersion step of dispersing the CNTs in the crystal grains of the titanium alloy.

(1) CNT coating step The CNT coating step in the present invention is a step of coating CNT with an element that reacts with carbon to generate carbide and a layer containing the carbide. In this step, first, CNT and powder made of an element that reacts with carbon to produce a carbide are put into a mixing container equipped with a stirring mixer and the like and mixed for about 15 to 30 minutes. Further, the powder used here may be any element that is made of an element that reacts with carbon to form a carbide, and preferably, a group consisting of silicon, chromium, titanium, vanadium, tantalum, molybdenum, zirconium, boron, and calcium. Is at least one selected from The particle shape and average particle size of the powder are not particularly limited, but the dispersibility of CNTs can be further improved by using a powder having an average particle size of 10 μm to 50 μm or less.

Next, the mixture taken out from the mixing container is filled into a non-sealed container capable of aeration between the inside and the outside. This non-sealed container is installed in a vacuum furnace provided with a sealed furnace body, a heating means for heating the inside of the sealed furnace body, and a vacuum pump for evacuating the inside of the sealed furnace body. Thereafter, while the inside of the closed furnace body is maintained in a vacuum state by a vacuum pump, the closed furnace body is heated by a heating means to sublimate a powder made of an element that reacts with carbon to generate a carbide. And this vapor | steam contacts CNT and forms the layer which covers the surface of CNT. This layer is composed of a carbide generated by a part of the sublimated element reacting with CNT and an unreacted element. Conditions such as the degree of vacuum, heating temperature, and heating time here may be appropriately set according to the type of powder to be used, but considering the balance between the manufacturing cost and the quality of the layer covering the CNT surface, The degree of vacuum may be 1 × 10 ⁻² Pa to 1 × 10 ⁻³ Pa, the heating temperature may be 1100 ° C. to 1500 ° C., and the heating time may be 5 hours to 10 hours. Further, the temperature increase rate and the temperature decrease rate are not particularly limited, but are preferably 100 ° C./h to 200 ° C./h.

  Thus, by coating CNT with the said element, when CNT is compounded with a titanium alloy, reaction of CNT and titanium can be suppressed.

(2) CNT immobilization step The CNT immobilization step in the present invention is a step of immobilizing the CNT obtained in the above-described CNT coating step on the surface of the titanium alloy powder. In this step, first, the CNT obtained in the CNT coating step is mixed with the titanium alloy powder. The mixing ratio of CNT and titanium alloy powder is not particularly limited, but from the viewpoint of further improving the mechanical properties of the titanium alloy as a base material, preferably, 0.1 mass% to 10 mass%, More preferably, it is desirable that 0.2% by mass to 3.0% by mass, and most preferably 0.4% by mass to 1.0% by mass of CNT be included in the mixture. Moreover, as titanium alloy powder used here, alpha type (for example, Ti-O, Ti-5Al-2.5Sn, etc.), near alpha type (for example, Ti-6Al-5Zr-0.5Mo-0.2Si). , Ti-5.5Al-3.5Sn-3Zr-0.3Mo-1Nb-0.3Si, Ti-8Al-1Mo-1V, Ti-6Al-2Sn-4Zr-2Mo), α + β type (for example, Ti- 6Al-4V, Ti-6Al-6V-2Sn, Ti-6Al-2Sn-4Zr-6Mo, Ti-4.5Al-3V-2Mo-2Fe, etc., near β type (for example, Ti-5Al-2Sn-2Zr-) 4Mo-4Cr, Ti-10V-2Fe-3Al, etc.), β-type (for example, Ti-15Mo-5Zr-3Al, Ti-11.5Mo-6Zr-4.5Sn, Ti-15V-3Cr-3Al) 3Sn, Ti-15Mo-5Zr, such as Ti-13V-11Cr-3Al) or may have any crystal structure. Further, a titanium alloy in which fine particles of TiB and / or TiC are dispersed in a metal structure as disclosed in JP-A-2005-76052 (based on Ti-15V-6Cr-4Al, a small amount of TiB and / or TiC). Additions or additions of TiB and / or TiC based on Ti-22V-4Al can also be suitably used. Considering the mechanical strength of the finally obtained titanium alloy composite material, Ti-6Al-4V, Ti-15Mo-5Zr-3Al, Ti-15V-3Cr-3Al-3Sn, Ti-10V-2Fe-3Al, Ti -4.5Al-3V-2Mo-2Fe and titanium alloys disclosed in JP-A-2005-76052 are preferred. The particle shape and average particle size of the titanium alloy powder are not particularly limited, but the mechanical properties of the composite titanium alloy can be further improved by using a powder having an average particle size of 10 μm to 50 μm. . Moreover, when 3 mass% or more of CNT is contained in a mixture, it is preferable to use a titanium alloy powder with a small average particle diameter from a viewpoint of suppressing aggregation of CNT. Furthermore, in order to improve strength, hardness, and wear resistance, it is preferable to add a small amount (1 to 10 wt%) of tungsten carbide (WC) nanoparticles (0.1 μm or less).

  Next, CNTs are immobilized on the surface of the titanium alloy powder by applying a mechanical impact force to the mixture of the CNT and the titanium alloy powder. Thereby, detachment | desorption of CNT from the surface of a titanium alloy powder particle is prevented, and a homogeneous sintered compact can be obtained in the sintering process mentioned later.

  Specific means for applying mechanical impact force include stirring devices such as a hybridization system (manufactured by Nara Machinery Co., Ltd.) and mechano-fusion system (manufactured by Hosokawa Micron), and dispersion devices using media particles. In addition, a dry mixing and stirring device such as a Henschel mixer or a V-type mixer can be used. Among these, in order to immobilize the CNTs more uniformly and firmly on the surface of the titanium alloy powder particles, the rotor and stator shear forces, the particle-to-particle collision forces, and the particle It is preferable to employ a hybridization system capable of giving a collision force with the wall.

(3) Sintering Step The sintering step in the present invention is a step of heating and sintering the CNT-fixed titanium alloy powder obtained in the above-described CNT fixing step. In this step, the CNT-immobilized titanium alloy powder obtained in the CNT immobilization step is formed into a molded body as necessary, and then a conventionally known sintering method in the art, for example, a pulse current sintering method, a hot press It is preferably sintered in a vacuum or an inert gas atmosphere by a method, a gas pressure sintering method, a hot isostatic pressing method, or the like. In the conventional method, titanium and most of the CNT react in the sintering process, whereas in the sintering process of the present invention, the reaction between the CNT and titanium is suppressed by the layer covering the CNT (of the CNT). Some react with titanium to produce titanium carbide), and the performance as a reinforcing material of CNT is maintained.

  The sintering conditions such as the sintering temperature and the sintering time may be appropriately set according to the employed sintering method and the type of titanium alloy used. For example, the sintering temperature is 800 ° C. to 1300 ° C., the sintering time is 5 What is necessary is just to carry out for minutes-2 hours.

  Among the sintering methods exemplified above, it is preferable to employ the pulse current sintering method as the sintering method from the viewpoint of more simply and obtaining a homogeneous sintered body in a short sintering time. When sintering by the pulse current sintering method, the graphite die is filled with the CNT-immobilized titanium alloy powder or the molded body thereof and, for example, the temperature is increased to 850 to 950 ° C. at a temperature increase rate of 50 to 100 ° C./min. Sintering may be performed for 5 to 10 minutes while applying a compressive load of 20 to 30 MPa under a vacuum degree of 4.0 Pa. In sintering by the pulse current sintering method, only neck growth between particles is promoted, and particle coarsening due to interparticle shrinkage hardly occurs, so the particle diameter before sintering is maintained and the structure is fine. A sintered body is obtained. Thus, since the sintered body has a fine structure, it becomes easier to disperse CNTs more uniformly in the crystal grains in the CNT dispersion step described later, and the mechanical strength of the resulting titanium alloy composite material is increased. improves.

(4) CNT Dispersion Step The CNT dispersion step in the present invention is a step in which the sintered body obtained in the above-described sintering step is subjected to plastic working to disperse CNTs within the crystal grains of the titanium alloy. As the plastic working, a conventionally known method in the technical field can be employed without limitation, and examples thereof include a rolling process, a forging process, and an extrusion process. Among these, it is preferable to employ at least one process selected from a hot rolling process and a constant temperature forging process in order to further refine crystal grains and more uniformly disperse CNTs. Is preferable because the mechanical strength of the titanium alloy composite material can be further improved by stretching the crystal grains into fibers.

  When plastic working is performed on a sintered body by a hot rolling process, rolling conditions such as rolling speed, rolling temperature, reduction ratio, etc. are not particularly limited, but a titanium alloy composite material with better mechanical strength is obtained. From the viewpoint, it is preferable that the rolling strain / pass: 0.1 to 0.2, the rolling temperature 700 ° C. to 850 ° C., and the rolling reduction 65% or more. In particular, if the rolling reduction is less than 65%, the dispersion of CNTs in crystal grains may be insufficient, and as a result, the mechanical strength of the titanium alloy composite material may be lowered, which is not preferable. The “rolling rate” here is defined by (h1−h2) × 100 / h1 (where h1: plate thickness before rolling, h2: plate thickness after rolling). The same rolling reduction (cross-sectional area reduction rate) is also required in hot extrusion. The “cross-sectional area reduction rate” here is defined by (S1-S2) × 100 / S1 (where S1: cross-sectional area before extrusion, S2: cross-sectional area after extrusion).

(5) Aging treatment step The method for producing a titanium alloy composite material of the present invention preferably includes a step of aging treatment of the titanium alloy composite material obtained in the above-described CNT dispersion step. This aging treatment may be appropriately set according to the type of titanium alloy used as a base material, and may be performed, for example, at 400 ° C. to 600 ° C. for 4 to 24 hours. By performing such an aging treatment, the mechanical strength of the titanium alloy composite material can be further improved. In particular, in order to improve the sliding characteristics, it is effective that the CNTs in the titanium alloy promote the formation of spherical fine titanium carbide.

Hereinafter, the present invention will be described more specifically and in detail by examples and comparative examples.
[Example 1]
Β-rich α + β-titanium alloy (Ti-4.5Al-) that is reinforced by combining PTFE fabric liner reinforced with polyamide fiber (Nomex: DuPont) as a back-up material and 0.8 wt% of CNT made by CVD method 3V-2Mo-2Fe: SP-700 alloy manufactured by JFE Steel Co., Ltd.) was subjected to a frictional wear test by the ring-on-disk method shown in FIG.

  The same applies to the case where the liner side mating material is a general-purpose titanium alloy (Ti-6Al-4V, comparative material 1) and hot die steel (SKD61 equivalent material: DHA1 manufactured by Daido Steel Co., Ltd., comparative material 2). A test was conducted for comparison. The wear test conditions were assumed for bearings for aircraft equipment, the sliding speed and surface pressure were constant, and the test was conducted without lubrication in the room temperature atmosphere. Details of the materials subjected to the test are shown in Table 1, and test conditions are shown in Table 2.

  The outline of the test is shown in FIG. 1, and the results of the frictional wear test are shown in FIGS. The titanium alloy composite material based on the SP-700 alloy indicated by symbol A in FIGS. 2 and 3 showed a very low friction coefficient, and the amount of wear increased correspondingly. The difference is obvious compared with the general-purpose Ti alloy of reference B, which is a comparative material, and shows an advantageous result even with respect to hot mold steel of reference C, which exceeds the hardness.

  4 and 5 show optical micrographs of the test piece of the present invention and the sliding surface of DHA1 (comparative material 2) after the abrasion test, respectively. Ti-6Al-4V (Comparative Material 1) was omitted because the liner was completely worn out and burned into the ring body. Compared to DHA1, which is harder and has a shorter sliding distance, this composite material has no noticeable scratches, and it can be confirmed that damage on the liner side (fiber fuzz etc.) is particularly small.

  As described above, the superiority of the combination of the composite material and the PTFE-based fabric liner is clear, and the sliding member exhibits a very low coefficient of friction, and stable operation can be expected over a long period of time.

[Example 2]
An outer ring 10 having a concave spherical sliding surface (material: Ti-6Al-) formed by fixing a PTFE fabric liner 20 having a thickness of 0.3 mm to the inner peripheral surface with a phenol resin (thermosetting resin adhesive). 4V titanium alloy) and an inner ring 30 having a convex spherical sliding surface that is held by the outer ring 1 and can relatively slide while contacting the concave spherical sliding surface (material: FIG. 6 shows a non-lubricated spherical plain bearing having the titanium alloy composite of the present invention. The inner ring which is the counterpart material of the liner surface is made of the titanium alloy composite material of the present invention.

  The PTFE-based fabric liner is the same as that of Example 1 reinforced with polyamide fiber (Nomex: DuPont) as a backup material. Further, as the titanium alloy composite material, a titanium alloy composite material reinforced by combining α + β titanium alloy (Ti-6Al-4V) and CNT prepared by a CVD method at a ratio of 0.5 wt% was used. In order to improve the strength and hardness of the titanium alloy composite material, an aging treatment was performed at 500 ° C. for 8 hours in an argon gas atmosphere, and the surface hardness was set to about HRC49. FIG. 7 shows an SEM photograph of the metal structure of the titanium alloy composite material. CNT reacts with matrix titanium and is distributed as fine spherical titanium carbide. Since a normal Ti-6Al-4V titanium alloy has a hardness of about HRC40, the spherical surface of the inner ring 3 is subjected to hard surface treatment such as ceramic coating, hard chrome plating and ion coating in order to prevent wear. In contrast, the titanium alloy composite material of the present invention is extremely compatible with PTFE-based fabric liners and has low wear and high hardness, so that the torque is stable over a long period of time without surface hardening treatment, etc. A lightweight spherical plain bearing can be obtained.

  It is also possible to configure a sliding member in which the inner peripheral surface of the outer ring 10 in FIG. 6 is cylindrical, and the inner ring is a circular ring member or shaft member whose outer peripheral surface is cylindrical.

  A sliding member having a Teflon liner that is used without lubrication can provide a lightweight, non-lubricating sliding member that has a long life and maintains little initial wear even when sliding over a long period of time.

A: Development material of the example,
B: Ti-6Al-4V of Comparative material 1
C: DHA1 of comparative material 2,
1 ... Ring body,
2 ... Polytetrafluoroethylene fabric liner,
3. Disc (partner material),
10 ... Outer ring,
20 ... polytetrafluoroethylene fabric liner,
30 ... Inner ring.

Claims (5)

  It has a pair of sliding surfaces that slide relatively while in contact with each other, one sliding surface is a polytetrafluoroethylene fabric liner, and the other sliding surface is carbon alloy added to a titanium alloy A non-lubricating sliding member made of a titanium alloy composite material, wherein the titanium alloy is a β-rich α + β titanium alloy.   The non-lubricated sliding member according to claim 1, wherein tungsten carbide nanoparticles are further added to the titanium alloy. The non-lubricated sliding member according to claim 1 or 2 , wherein the carbon nanotube is distributed as fine spherical titanium carbide in the metal structure of the titanium alloy composite material. The one sliding surface is a sliding surface formed by fixing a polytetrafluoroethylene fabric liner to a cylindrical inner peripheral surface or outer peripheral surface, and the other sliding surface is a cylindrical outer peripheral surface. The non-lubricating sliding member according to claim 1, wherein the non-lubricating sliding member is an inner peripheral surface.   The non-lubricating sliding member has a first member having a concave spherical first sliding surface formed by fixing a polytetrafluoroethylene-based fabric liner to the inner peripheral surface, and is held by the first member And a second member having a convex second spherical sliding surface made of a titanium alloy composite material capable of relatively sliding while being in contact with the first sliding surface. The non-lubricated sliding member according to any one of claims 1 to 4, which is a spherical plain bearing.

Images