BR112020009350A2 - sliding member and method for manufacturing it - Google Patents

Abstract

  The present invention relates to a sliding member in which the sliding layer is capable of exhibiting excellent sliding characteristics in terms of seizure resistance, wear resistance and heat resistance. A method for manufacturing the sliding member of the present invention is a method for making a sliding member to manufacture a sliding member that slides with a corresponding material. The manufacturing method includes the cross-linking step to irradiate particulate ultra-high molecular weight polyethylene with radiation rays in a sealed state, and the cross-linking of ultra-high molecular weight polyethylene, a composition preparation step to prepare a composition for a sliding layer containing a solid lubricant and the bonding resin, and a sliding layer forming step to form the sliding layer that slides with the corresponding material by providing the composition for a sliding layer in a base material, and obtaining the sliding member. The solid lubricant includes the ultra-high molecular weight polyethylene cross-linked in the cross-linking step.

Description

Descriptive Report of the Invention Patent for "SLIDING MEMBER AND METHOD FOR MANUFACTURING THE SAME". Technical Field

[0001] The present invention relates to a sliding member and a method for its manufacture. Background of the Technique

[0002] Conventionally, the sliding members shown in Patent Literature 1 and 2 are known. Such sliding members each include a base material formed from a steel material or an aluminum material, and a sliding layer formed over the base material. An underlying layer can be provided between the base material and the sliding layer. The sliding layer contains a bonding resin and a solid lubricant. The binding resin is formed from an epoxy resin or the like. The solid lubricant in Patent Literature 1 is formed from particulate molybdenum disulfide (MoS2), particulate polytetrafluoroethylene (PTFE), and particulate polyethylene. Recently, an ultra-high molecular weight polyethylene has been studied due to the characteristics of self-lubrication and wear resistance, and the solid lubricant in Patent Literature 2 includes particulate and cross-linked ultra-high molecular weight polyethylene.

[0003] These sliding members can be adopted on a propeller shaft, a piston and the like, in which the sliding layers slide with the corresponding material. In particular, the sliding layer in Patent Literature 1 includes polyethylene which has good affinity for lubricants as a solid lubricant and, therefore, achieves a low friction coefficient and high wear resistance. In addition, the sliding layer in Patent Literature 2 uses a cross-linked ultra-high molecular weight polyethylene as a solid lubricant, and performs not only seizure and wear resistance, but also high heat resistance. Patent Literature

[0004] Patent Literature 1: Japanese Patent Open to Public Inspection No. 2013-189569

[0005] Patent Literature 2: Japanese Patent Open to Public Inspection No. 2016-69508 Summary of the Invention Technical Problem

[0006] However, for sliding members, further improvement in sliding characteristics is desired to ensure reliability. In this regard, according to the result of the test by the inventors, the sliding layer may not always exhibit high heat resistance when the cross-linked ultra-high molecular weight polyethylene is simply irradiated with radiation rays, even if the polyethylene of cross-linked ultra-high molecular weight is adopted as part of the solid lubricant. In some cases, the cross-linked ultra-high molecular weight polyethylene becomes brittle, and the lubrication characteristics of the sliding layer deteriorate.

[0007] The present invention was made in the light of the conventional circumstances described above, and an objective of the present invention is to provide a sliding member in which a sliding layer can exhibit excellent sliding characteristics in terms of seizure resistance, wear resistance and resistance to heat. Solution to the Problem

[0008] A method for making a sliding member of the present invention is a method for making a sliding member, for making a sliding member that slides with a corresponding material, and includes: a cross-linking step to irradiate ultra-molecular weight polyethylene high particulate with radiation rays in a sealed state, and the crosslinking of ultra-high molecular weight polyethylene; a composition preparation step to prepare a composition for a sliding layer containing a solid lubricant that includes the ultra-high molecular weight polyethylene cross-linked in the cross-linking step, and a binder resin; and a sliding layer forming step to form a sliding layer that slides with the corresponding material by providing the composition for a sliding layer in a base material, and to obtain the sliding member.

[0009] According to the inventors' test results, in the sliding member obtained by the manufacturing method of the present invention, excellent resistance to seizure and wear resistance can be improved by the crosslinked ultra-high molecular weight polyethylene. It is assumed that the feed for this is that in the manufacturing method of the present invention, the particulate ultra-high molecular weight polyethylene is irradiated with radiation rays in the sealed state in the crosslinking step, so that the ultra molecular weight polyethylene -high is hardly oxidized and is properly crosslinked. When particulate ultra-high molecular weight polyethylene is irradiated with radiation rays in an open state to the atmosphere, ultra-high molecular weight polyethylene is oxidized, and ultra-high molecular weight polyethylene is hardly cross-linked.

[00010] According to the inventors' test results, the crosslinking step is preferably carried out under a condition that an absorbed dose of electron beams such as radiation rays is greater than or equal to 60 kGy and less than 500 kGy. The electron beams are easy to handle. When the electron beams are irradiated at the dose absorbed in this range, the ultra-high molecular weight polyethylene is properly cross-linked, and the sliding layer exhibits excellent heat resistance and wear resistance. When the crosslinking step is performed at the absorbed dose of electron beams less than 60 kGy, the crosslinking of the ultra-high molecular weight polyethylene becomes insufficient, and the wear resistance of the sliding layer is not sufficient. When the crosslinking step is performed at the absorbed dose of electron beams of 500 kGy or more, the crosslinked ultra-high molecular weight polyethylene becomes brittle, and the wear resistance of the sliding layer deteriorates.

[00011] A sliding member of the present invention is a sliding member that includes a base material, and a sliding layer formed on the base material, and which contains a binder resin and a solid lubricant, the sliding layer that slides with a material corresponding; wherein the solid lubricant includes the cross-linked ultra-high molecular weight polyethylene that is particulate and has a melting point that is greater than 126.4 ° C and less than or equal to 132.0 ° C.

[00012] According to the inventors' test results, when the melting point of ultra-high molecular weight polyethylene is within this range, a friction coefficient of the sliding layer is low, the amount of wear is small, and the ultra-high molecular weight polyethylene is hardly liquefied and leaves the surface of the sliding layer at high temperatures. This is presumed due to the fact that the ultra-high molecular weight polyethylene is properly cross-linked. Accordingly, the sliding layer can enhance excellent seizure and wear resistance.

[00013] According to the inventors' test result, ultra-high molecular weight polyethylene preferably has a gel fraction greater than or equal to 26%. In this case, the friction coefficient of the sliding layer is low, the amount of wear is small, and the ultra-high molecular weight polyethylene is hardly liquefied from the surface of the sliding layer at high temperatures. Ultra-high molecular weight polyethylene with the gel fraction in this range is presumed to be properly cross-linked.

[00014] According to the inventors' test results, in the sliding layer, the solid lubricant is preferably greater than or equal to 25% by volume and less than or equal to 100% by volume with respect to the binder resin. In that case, the binder resin can keep the solid lubricant better. Furthermore, in the sliding layer, the binder resin is preferably polyamide-imide. In addition, ultra-high molecular weight polyethylene is preferably greater than or equal to 5% by volume and less than or equal to 35% by volume with respect to all solid components in the sliding layer. In this case, the sliding layer can further improve wear resistance under dry or oily environments.

[00015] According to the inventors' test results, the solid lubricant preferably also includes molybdenum disulfide. In addition, in the sliding layer, molybdenum disulfide is preferably less than or equal to 26% by volume with respect to all solid components in the sliding layer. In this case, the sliding layer can improve wear resistance under dry or oily environments.

[00016] According to the inventors' test results, in the sliding layer, ultra-high molecular weight polyethylene is preferably greater than or equal to 23% by volume and less than or equal to 35% by volume with with respect to all solid components in the sliding layer, and molybdenum disulfide is preferably less than or equal to 15% by volume with respect to all solid components in the sliding layer. In this case, the sliding layer can further improve wear resistance under dry environments, in particular.

[00017] According to the inventors' test results, the solid lubricant preferably also includes graphite. In addition, in the sliding layer, the graphite is greater than or equal to 5% by volume and less than or equal to 30% by volume with respect to all solid components in the sliding layer. In this case, the sliding layer can further improve wear resistance under dry or oily environments. i. Advantageous Effects of the Invention

[00018] According to the manufacturing method of the present invention, the sliding member on which the sliding layer can exhibit excellent sliding characteristics in terms of seizure resistance, wear resistance and heat resistance can be manufactured. In addition, according to the sliding member of the present invention, the sliding layer can exhibit excellent sliding characteristics in terms of self-lubrication, wear resistance and heat resistance. Brief Description of Drawings

[00019] Figure 1 is a schematic perspective view showing an alternative test status pin on the disk in test 1;

[00020] Figure 2 is a sectional view showing a state of a swash-shoe plate test in test 2;

[00021] Figure 3 is a photograph of SEM image of power 500 in test sliding layer 1, in a sliding member of mode 1;

[00022] Figure 4 is a photograph of SEM image of power 500 in the sliding layer in test 1, in a sliding member of mode 2;

[00023] Figure 5 is a photograph of SEM image of power 500 in the sliding layer in test 1, in a sliding member of modality 3;

[00024] Figure 6 is a photograph of SEM image of power 500 in the sliding layer in test 1, in a sliding member of modality 4;

[00025] Figure 7 is a photograph of SEM image of power 500 in the sliding layer in test 1, in a sliding member of comparative example 2;

[00026] Figure 8 is a photograph of SEM image of power 500 in the sliding layer in test 1, in a sliding member of comparative example 3;

[00027] Figure 9 is a schematic perspective view showing a state of a friction and ring wear test on the disc in test 4;

[00028] Figure 10 is a schematic perspective view showing a state of a friction and pin wear test on the disk in test 5. Description of Modalities

[00029] As a means to irradiate particulate ultra-high molecular weight polyethylene with radiating rays in a sealed state, (1) a vacuum method to evacuate a container that stores particulate ultra-high molecular weight polyethylene to reduce the proportion of existence of air; (2) a method of purging gas to fill a container with inert gas or nitrogen to discharge air, and the like can be adopted. An atmosphere can include some oxygen without using a vacuum method or a gas purge method, as long as the atmosphere is sealed.

[00030] As radiation beams, X-rays, electron beams, and ion beams can be adopted in addition to α rays, β rays, and γ rays. A quantity of radiation rays is expressed as a dose proportional to the energy absorbed in a unit mass. A gray (Gy) is a unit that represents an amount of energy absorbed by a given substance (referred to as an absorbed dose) when the radiation rays reach the substance. Preparation stage of Binder Resin Composition

[00031] A binder resin exhibits a retention property for a solid lubricant that makes it difficult to separate the solid lubricant, of durability against a shear force that acts repeatedly under a layered coating film (hardness as a base), of wear resistance with which the binder resin is difficult to break, heat resistant and the like. As the binder resin, a polyimide resin, an epoxy resin, a phenol resin and the like can be adopted. As the polyimide resin, polyamide-imide (PAI), polyimide and the like can be adopted. Considering the cost and characteristics, the ideal is to use PAI as the bonding resin. Solid Lubricant

[00032] A solid lubricant is maintained by the binder resin, and exhibits a low shear force and a low friction coefficient on an outer surface. As the solid lubricant, fluororesin, molybdenum disulfide, graphite, ultra-high molecular weight polyethylene and the like can be adopted. Fluororesin and ultra-high molecular weight polyethylene improve the sliding ability by forming a coating film on a sliding surface of a sliding layer, and transferring it to a corresponding material. Molybdenum disulfide and graphite improve the sliding ability through a crystalline structure with low shear strength, and perform low friction under a high load. According to the test results by the inventors, fluororesin has sliding characteristics, such as wear resistance and seizure resistance, but has oil repellency, and has a relatively large lubricating oil contact angle. On the other hand, ultra-high molecular weight polyethylene has lipophilic properties although it is inferior to fluororesin in terms of sliding characteristics, and has a relatively small lubricating oil contact angle. In addition, as the solid lubricant, melamine cyanurate (MCA), calcium fluoride and soft metals, such as copper and tin, can be adopted. In particular, ultra-high molecular weight polyethylene that is properly cross-linked is unlikely to be liquefied from a surface of a sliding layer at high temperatures, and can enhance excellent seizure and wear resistance.

[00033] The ultra-high molecular weight polyethylene previously cross-linked preferably has an average molecular weight of 1,000,000 to

7,000,000. In addition, a specific gravity of the ultra-high molecular weight polyethylene previously cross-linked is preferably 0.92 to 0.96. The ultra-high molecular weight polyethylene previously cross-linked preferably has a particle size less than or equal to 30 µm, and preferably still has a particle size less than or equal to 15 µm, in terms of smoothness surface and wear resistance. Additive

[00034] The sliding layer can have an additive in addition to the binder resin and the solid lubricant. Like the additive, additives that increase the hardness of the sliding layer can be adopted, such as rigid particles of titanium dioxide, tricalcium phosphate, alumina, silica, silicon carbide and silicon nitride.

[00035] The sliding layer may contain a metal compound containing sulfur, such as ZnS and Ag2S as an extreme pressure agent. In addition, the sliding layer may have a surfactant, a coupling agent, a processing stabilizer, an antioxidant and the like.

[00036] As a silane coupling agent used for the treatment of silane coupling, a functional group is preferably an epoxy group. As the silane coupling agent that has an epoxy group in the functional group, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane are preferable. These silane coupling agents also have excellent storage stability. Sliding Layer Formation Stage

[00037] As a sliding layer formation step, it is possible to carry out viscosity adjustment and density adjustment of a solid content by properly diluting a composition for a sliding layer with a solvent such as n-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, or xylene, depending on a type of coating method, such as spray coating and rolling coating. It is possible to form a sliding layer when carrying out drying and burning after coating a base material with a diluent of the composition for a sliding layer. First Experiment Modalities

[00038] From here on, modalities 1 to 4 embodying the present invention, and comparative examples 1 to 3 will be described. First, the following materials were prepared. Binder resin: polyamide-imide resin varnish (PAI) Solid lubricant: particulate ultra-high molecular weight polyethylene (UHPE particle), composed of particulate fluorine (PTFE particle), MoS2, graphite.

[00039] A plurality of bags formed by vinyl that are capable of being airtight and of the same size were prepared, a fixed amount of UHPE particles were placed in each of these bags and the respective bags were evacuated under the same conditions. Subsequently, each bag was placed in an electron beam irradiation device and the UHPE particles were irradiated with electron beams as radiation rays at an absorbed dose (kGy) shown in Table 1. In this way, the particles of UHPE of cross-linked products No. 1 to 6 were obtained. The UHPE particles of a non-crosslinked product were not irradiated with electron beams. The UHPE particles of an unsealed cross-linked product were irradiated with electron beams in an open state to the atmosphere, that is, without being placed in the bag.

[00040] Table 1 shows the melting points (° C), gel fractions (%), and average particle size (µm) of the respective UHPE particles. In addition, Table 1 also shows a melting point (° C) and an average particle size (µm) of PTFE particles. Table 1 Com- Particulate ultra-high molecular weight polyethylene (UHPE particle) particle Fluid Product Product Product Product Product Product Product Non-crosslinked crosslinked crosslinked crosslinked crosslinked crosslinked PTFE reticu- 1 side N ° side N ° 3 side N ° 4 side N ° 5 side N ° no side 2 6 sealed Atmosphere of - - Sealed Sealed sealed sealed sealed sealed Open to atmosphere radiation electron beam Dose 0 0 60 80 100 300 500 1,000 100 electron beam absorbed [KGy] 323.8 point 134.6 132.0 131.6 131.2 128.2 126.4 123.0 133.2 melting [° C] Gel fraction - 0 26 69 66 69 68 71 0 [% by weight] Size 5 10 10 10 10 10 10 10 10 10 average of particles [µm]

[00041] Here, the melting point measurement conditions are as follows. Analysis equipment: DSC Q2000 (TA instrument) Heating rate: 5 ° C / minute (after the temperature was raised to 210 ° C, the temperature was cooled to 30 ° C at - 20 ° C / minute, and the measurement was performed again). Atmosphere: N2 Sample weight: 5 mg ± 0.1 mg each Melting point reading conditions: a peak melting temperature when measured again.

[00042] Gel fractions were measured as follows. First, each powder was pressed in a constant pressure, while it was heated to 180 ° C to 230 ° C and, thus, a sheet having a thickness of 0.3 mm was formed. From each sheet, a small part of 0.3 g was cut. Each small part was placed in a flask, and 500 mm of p-xylene was added to the flask. While heating each flask to 130 ° C, the mixture in the flask was stirred for four hours to dissolve each small part. The solution was filtered with a wire mesh that has a mesh of 106 µm, while the solution is in a high temperature state of 130 ° C. The insoluble matter in the wire mesh was dried under vacuum at 140 ° C for 3 hours, and a weight (g) of the insoluble matter after the ambient temperature was measured. Subsequently, the gel fraction was obtained by a gel fraction formula (%) = weight of insoluble matter (g) x 100 / 0.3 (g).

[00043] As the composition preparation step, the PAI varnish and each solid lubricant were compounded in a proportion of composition shown in Table 2, and after the compound was well stirred, the compound passed through three roller mills, by which compositions for the sliding layers in modalities 1 to 4 and comparative examples 1 to 3 were prepared. The solid lubricant is formed from PTFE particles, UHPE particles, MoS2 and graphite. The UHPE particles are either a non-crosslinked product, No. 1 to 4 crosslinked products or an unsealed crosslinked product. Table 2% in Modali- Modali- Modali- Modali- Example Example Example volume 1 1 2 2 3 3 4 Compa- Compa- Comparative 1 rative 2 rative 3 50 50 50 50 50 50 50 varnish

PAI Lubrifi- Partí- - - - - 18 - - sing solid PTFE Partí- Product not - - - - - 18 - reticulate cell

UHPE Produ- N ° 1 18 - - - - - to reti- N ° 2 - 18 - - - - - culprit N ° 3 - - 18 - - - - N ° 4 - - - 18 - - - No - - - - - - 18 sealed Molybdenum disulfide 18 18 18 18 18 18 18 Graphite 14 14 14 14 14 14 14% by volume of solid lubricant per 100 100 100 100 100 100 100 100 100% by volume of PAI resin

[00044] The sliding layer formation step below was carried out. First, the respective compositions for the sliding layers were diluted with a solvent to make the dilutions, the respective dilutions were coated on the base material formed from a steel material, after which, drying was carried out, and the burning was performed at 220 ° C for 1.5 hours. After that, the grinding of the surface was carried out to match the thickness of the film, and the sliding layers of the film thickness of 15 µm were formed. In this way, the respective sliding members of modalities 1 to 4 and comparative examples 1 to 3 were obtained.

[00045] The respective sliding members are each formed by the base material and by the sliding layer formed on the base material. The sliding layer contains the bonding resin and the solid lubricant. The respective sliding members were provided for tests 1 to 3 as follows. Test 1 (alternate test pin on the disk)

[00046] The test serves to confirm a state of (residual) liquefaction of the UHPE particles in the sliding layer of each of the sliding members. In other words, as shown in Figure 1, each sliding member 10 is positioned on a plate 1 on which a top surface can be heated. In that state, each sliding member 10 has a sliding layer 10a as the top surface. In the sliding layer 10a, a pin 2 produced from SUJ2 with a tip end curvature of 10R is alternated under conditions of a 350 gf load, an alternating distance of 20 mm, a speed of 2 Hz, and an alternating number 3500. At that time, a temperature of a substrate surface is controlled at 80 ° C, and a lubricant 3 containing hydrocarbon oil is poured onto the sliding layer 10a. The test was performed on sliding members of modalities 1 to 4 and comparative examples 1 to 3. Test 2 (swash-shoe plate 1 test)

[00047] The test serves to evaluate a coefficient of friction and rupture under a dry environment in a swash plate compressor. In other words, as shown in Figure 2, a base 20 material was formed on a suit from a compressor swash plate, a sliding layer 20a was formed on each of the 20 base materials, and the swash plate was obtained as described above. Meanwhile, a shoe 5 produced from SUJ2 was held by a holding tool 4. Subsequently, the swash plate was rotated at a sliding speed of 10 m / second, a 1960 N load was applied between the swash plate and the shoe 5, and a time (second) required for the swash plate and shoe 5 to break was investigated. The test was performed on sliding members of modalities 1 to 4 and comparative examples 1 to 3. Test 3 (swash-shoe plate 2 test)

[00048] The test serves to evaluate the rupture when applying a gradual load under oil lubrication in a swash plate compressor. In other words, as shown in Figure 2, the base material 20 was formed in the shape of a compressor swash plate, a sliding layer 20a was formed in each of the base 20 materials, and the swash plate was obtained as described above. Meanwhile, a shoe 5 produced from SUJ2 was held by a holding tool 4. Subsequently, the swash plate was rotated at a sliding speed of 7 m / second, while the oil from the cooling machine was fixed to the surface of the plate swash for the amount of 6 g / minute, a load of 400 N was applied between the swash plate and shoe 5 every five minutes, and a load (N) under which the swash plate and shoe 5 were broken was investigated. The test was performed on sliding members of modalities 1 to 4 and comparative examples 1 to 3.

[00049] Table 3 shows the results of the tests. In addition, the remaining states of the UHPE particles in the sliding layers of the respective sliding members of modalities 1 to 4 and comparative examples 2 and 3 after test 1 were confirmed by the SEM images. Figure 3 shows a picture of SEM power 500 on the test sliding layer 1, on the sliding member of mode 1. Figure 4 shows a picture photograph of SEM power 500 on the test sliding layer 1, on the sliding member of mode 2. Figure 5 shows a picture of SEM of power 500 on the sliding layer of test 1, on the sliding member of mode 3. Figure 6 shows a picture of SEM of power 500 on the sliding layer of test 1 , in the sliding member of mode 4. Figure 7 shows a picture of SEM of power 500 in the sliding layer of test 1, in the sliding member of comparative example 2. Figure 8 shows a picture of SEM image of power 500 in test sliding layer 1, in the sliding member of comparative example 3. Table 3

Test 2 Test 3

Load Time Coefficient of Friction Break Break [N] [second]

Modality 1 0.33 510 4,000

Modality 2 0.33 479 5,600

Modality 3 0.32 524 5,600

Modality 4 0.33 451 4,800

Example 0.33 465 3,600 comparative 1

Example 0.38 235 4.000 comparative 2

Example 0.36 293 3,600 comparative 3

[00050] As can be seen from Table 3, the sliding members of modalities 1 to 4 can exhibit excellent resistance to seizure and resistance to wear. It is assumed that the reason for this is that the sliding members of modalities 1 to 4 adopt UHPE particles irradiated with radiation rays in the sealed state, the UHPE particles are hardly oxidized, and are properly crosslinked.

[00051] In particular, the sliding layers on the sliding members of modalities 2 to 4 exhibit excellent resistance to seizure and wear resistance. This is assumed due to the fact that the sliding members of modalities 2 to 4 each adopt crosslinked UHPE particles that have a melting point greater than or equal to 128.2 ° C and less than or equal to 132.0 ° C, and a fraction of gel greater than or equal to 26% when having an absorbed dose of electron beams greater than or equal to 60 kGy and less than or equal to 300 kGy as shown in Table 1, so that the particles of UHPE are hardly liquefied and leave the surface of the sliding layer at high temperatures, as shown in Figures 4 to

6.

[00052] On the other hand, as can be seen from Table 3, the sliding members of comparative example 2 and 3 each have a low breaking load and low resistance to seizure. This is presumed due to the fact that the sliding member of comparative example 2 adopts UHPE particles from a non-crosslinked product and therefore the UHPE particles are easily liquefied and leave the surface of the sliding layer at high temperatures as shown in Figure 7 In addition, it is assumed that this is because the sliding member of comparative example 3 adopts UHPE particles from an unsealed crosslinked product that has a 0% gel fraction, so that the UHPE particles are oxidized and are not appropriately cross-linked, and UHPE particles are easily liquefied and leave the surface of the sliding layer at high temperatures as shown in Figure 8.

[00053] Accordingly, it has been shown that the sliding members of modalities 1 to 4, in particular the sliding members of modalities 2 to 4, the sliding layers can exhibit excellent sliding characteristics in terms of self-lubrication, wear resistance and resistance to heat. Therefore, it has been revealed that if these sliding members are adopted in swash plates or similar to the compressors, better compressors can be obtained. Second Experiment

[00054] In the following, modalities 5 to 18 that embody the present invention, and comparative examples 4 to 8 will be described. First, as in the first experiment, as a composition preparation step, the PAI varnish and each solid lubricant were composed in a proportion of composition shown in Tables 4 to 6, and after the compound was well stirred, the compound passed through three roller mills, through which the compositions for the sliding layers in modalities 5 to 18 and comparative examples 4 to 8 were prepared. Subsequently, as in the first experiment, a sliding layer formation step was performed. In this way, the respective sliding members of modalities 5 to 18 and comparative examples 4 to 8 were obtained.

Table 4% in Modali- Modali- Modali- Modali- Modali- Modali- Volume 5 Age 6 Age 7 Age 8 Age 9 Age 10 Age 50 50 50 50 50 50 50 50 Varnish

PAI Lubrifi- Particle - - - - - - - Sing of solid PTFE Particle Product not - - - - - - - of reticulate

UHPE Product N ° 1 - - - - - - - reticu- N ° 2 - - - - - - - side N ° 3 25 35 28 23 22,5 15 10 N ° 4 - - - - - - - N ° 5 - - - - - - - N ° 6 - - - - - - - Molybdenum disulfide 15 9 0 8 22.5 15 10 Graphite 10 6 22 19 5 20 30% by volume of solid lubricant per 100 100 100 100 100 100 100 100% by volume of PAI resin

Table 5% by volume Modali- Modali- Modali- Modali- Modali- Modality Dade 14 Dice 15 Dude 16 Dude 17 12 13 FATHER'S PAINT 80 50 50 50 50 80 80 80 Lubricated- - - - - - - - Sing solid PTFE cell Parti- Product not - - - - - - - UHPE lattice cell Produ- N ° 1 - - - - - - - to reti- N ° 2 - - - - - - - culado N ° 3 10 5 10 15 25 7.5 10 N ° 4 - - - - - - - N ° 5 - - - - - - - N ° 6 - - - - - - - Molybdenum disulfide 0 26 23 25 25 7.5 10 Graphite 10 10 17 10 0 5 0% by volume of solid lubricant per 25 100 100 100 100 25 25 100% by volume of PAI resin

Table 6% by volume Example Example Example Example Comparative example 4 comparative comparative comparative comparative 5 6 7 8 PAI varnish 50 50 40 40 40 Lubricated - Particle - - - - - solid PTFE particle Particle Product not - - - - - UHPE lattice Product N ° 1 - - - - - reticu- N ° 2 - - - - - side N ° 3 - - 22.5 30 30 N ° 4 - - - - - N ° 5 18 - - - - - N ° 6 - 18 - - - Molybdenum disulfide 18 18 22.5 30 0 Graphite 14 14 15 0 30% by volume of solid lubricant per 100 100 150 150 150 100% by volume of PAI resin

[00055] The respective sliding members of modalities 1 to 4 and comparative examples 1 and 2 obtained by the first experiment, and the respective sliding members of modalities 5 to 18 and comparative examples 4 to 8 obtained by the second experiment were provided for tests 4 and 5 this way. Test 4 (friction and ring wear test on the disc: under dry environment)

[00056] The test serves to evaluate the resistance to wear under a certain level of a dry environment in the sliding layers of the respective sliding members. In other words, as shown in Figure 9, a sliding layer 30a of each of the sliding members is formed on a top surface of a base material 30 formed by S45C. A film thickness of the sliding layer 30a is approximately 20 µm. In this state, a ring 6 is positioned on a top surface of the sliding layer 30a of each of the sliding members. Ring 6 made of S45C is rotated under conditions of contact pressure of 5.4 MPa, a sliding speed of 0.9 m / second, and a sliding distance of 500 m. A specific amount of wear (x10-6mm³ / N · m) of the sliding layer 30a during this was measured. The test was performed on sliding members of modalities 1 to 18 and comparative examples 1, 2 and 4 to 8. Test 5 (friction and pin wear test on the disc: under oily environment)

[00057] The test serves to assess a wear resistance under a certain level of an oily environment in the sliding layers of the respective sliding members. In other words, as shown in Figure 10, the sliding layer 40a of each of the sliding members is formed on a top surface of a base material 40 formed by S45C. A film thickness of the sliding layer 40a is approximately 15 µm. In this state, a pin 7 is positioned on a top surface of the sliding layer 40a of each of the sliding members. Pin 7 made of SUJ2 in which a curvature of one end of the tip is 10R is rotated under conditions of a load of 20N, the sliding speed of 0.25 m / second, and a sliding distance of 22.6 m. At that time, 5 mg of a cooler oil 8 was poured onto the sliding layer 40a, and a wear depth of the sliding layer 40a during this was measured. The test was performed on sliding members of modalities 1 to 18 and comparative examples 1, 2 and 4 to 8.

[00058] Table 7 shows the results of test 4 and test 5 on sliding members of modalities 1 to 4 and comparative examples 1 and 2. Tables 8 to 10 show the results of test 4 and testo 5 on sliding members of modalities 5 to 18 and comparative examples 4 to 8. Table 7 Modality Modality Modality Example Example 1 2 3 4 comparative 1 comparative 2 Test Quantity of 2.4 2.8 2.2 5.6 5.7 3.6 4 wear specific x10 ^ - 6 [mm³ / N · m] Test Depth of 2.9 2.2 4.1 2.7 20.1 9.1 5 wear [µm] Table 8 Modality Modality Modality Modality Modality Modality 5 6 7 8 9 10 11 Test Quantity 1.3 0.7 0.5 0.5 2.9 3.2 1.6 4 specific wear x10 ^ - 6 [mm³ / N · m] Test Depth 4.7 2.6 4.3 4.2 4.4 3.4 2.4 5 of wear [µm]

Table 9 Modality Modality Modality Modality Modality Modality 12 13 14 15 16 17 18 Test Quantity of 2.3 1.5 3.4 2.8 2.2 7.8 5.1 5.1 specific wear x10 ^ -6 [mm³ / N · m] Test Depth of 1.0 11.3 17.5 17.3 15.0 1.0 1.0 5 wear [µm] Table 10 Example Example Example Example Comparative Comparative Comparative Comparative Comparative Example 4 5 6 7 8 Test Quantity of 9.7 7.7 4.4 4.9 6.3 4 specific wear x10 ^ - 6 [mm³ / N · m] Test Depth of 11.5 11.0 14.5 12.6 14.1 5 wear [µm]

[00059] In the evaluation of the wear resistance of the sliding members of modalities 1 to 18, the wear resistance of the sliding member of comparative example 2 was used as a criterion. The reason for this is that although the UHPE particles are appropriately cross-linked in the sliding members of modalities 1 to 18, the UHPE particles are not cross-linked in the sliding member of comparative example 2, as can be seen from Tables 2 and 4 to 6 and, therefore, the presence or absence of crosslinking of UHPE particles was adopted as a criterion.

[00060] As can be seen from Tables 7 to 10, in the respective sliding members of modalities 1 to 18, the specific amount of wear is less than 3.6 (x10-6mm³ / N · m), or the depths of wear are less than 9.1 (µm) when the results of tests 4 and 5 on the sliding member of comparative example 2 are the standards. In other words, the sliding members of modalities 1 to 18 can exhibit excellent wear resistance under the dry environment or under the oily environment. The reason for this is assumed to be that, as long as the sliding members of modalities 1 to 18 adopt UHPE particles irradiated with radiation rays in the sealed state, UHPE particles are hardly oxidized, and are crosslinked in an appropriate manner. In particular, in the sliding members of modalities 1 to 3 and 5 to 12, the sliding layers exhibit excellent wear resistance under the dry environment and under the oily environment.

[00061] Furthermore, it is assumed that, since the sliding members of modalities 1 to 18 adopt the crosslinked UHPE particles that have melting points greater than 126.4 ° C and less than or equal to 132.0 ° C, and gel fractions greater than or equal to 26% when absorbed doses of electron beams greater than or equal to 60 kGy and less than 500 kGy, as shown in Table 1, UHPE particles are hardly liquefied and leave the surfaces of the sliding layers at high temperatures.

[00062] On the other hand, as can be seen from Tables 7 to 10, the sliding members of comparative example 1, 2, 4 and 5 have a specific amount of wear greater than or equal to 3.6 (x10 - 6 mm³ / N · m), and wear depths greater than or equal to 9.1 (µm), in test results 4 and 5. Accordingly, the sliding members of comparative example 1, 2, 4 and 5 have low resistance to wear under both the dry and the oily environment, compared to the sliding members of modalities 1 to 18. It is assumed that the sliding member of comparative example 1 adopts a fluorine compound (PTFE particles) instead of the particles of UHPE, which are properly crosslinked and therefore have low wear resistance. The sliding member of comparative example 2 is assumed to adopt the non-crosslinked UHPE particles with a melting point of 134.6 ° C, and therefore the UHPE particles are easily liquefied and leave the surface of the sliding layer at high temperatures. . Furthermore, it is assumed that since in the sliding members of comparative example 4 and 5, the absorbed doses of electron beams are greater than or equal to 500 kGy, the crosslinked UHPE particles are brittle, and the wear resistance of the sliding members deteriorates.

[00063] Accordingly, it has been shown that in the sliding members of modalities 1 to 18, the sliding layers can exhibit excellent wear resistance under the dry environment or under the oily environment. In particular, in the sliding members of modalities 1 to 3 and 5 to 12, the sliding layers can exhibit excellent wear resistance under the dry environment or under the oily environment.

[00064] In the sliding layer, the solid lubricant is preferably greater than or equal to 25% by volume and less than or equal to 100% by volume with respect to the binder resin, and the ultra-high molecular weight polyethylene it is preferably greater than or equal to 5% by volume and is less than or equal to 35% by volume with respect to all solid components in the sliding layer. More specifically, the sliding members of modalities 1 to 18 can exhibit excellent wear resistance under the dry environment or under the oily environment to the sliding members of comparative example 6 to 8. In other words, in the sliding members of comparative example 6 to 8, the amount of specific wear is greater than 3.6 (x10-6mm³ / N · m), and the wear depths are greater than 9.1 (µm) in test results 4 and 5. It is assumed that since in the sliding members of comparative example 6 to 8, the solid lubricants were 150% by volume with respect to the binder resin, the binder resins were not able to retain the solid lubricants, and the solid lubricant left the surface of the sliding layer at high temperatures.

[00065] In the sliding layer, molybdenum disulfide is preferably less than or equal to 26% by volume with respect to all solid components in the sliding layer. In this case, in the sliding layer, the wear resistance can be improved under a dry environment or under an oily environment. In addition, as in the sliding members of modalities 7 and 12, molybdenum disulfide does not need to be included in the solid lubricant.

[00066] In the sliding layer, ultra-high molecular weight polyethylene is preferably greater than or equal to 23% by volume and less than or equal to 35% by volume with respect to all solid components in the sliding layer, and molybdenum disulfide is preferably less than or equal to 15% by volume with respect to all solid components in the sliding layer. In that case, the sliding layer can further improve wear resistance under the particular dry environment. More specifically, the sliding members of modalities 5 to 8 can exhibit excellent wear resistance under the dry environment. In the sliding members of modalities 5 to 8, the amount of specific wear is within a range of 0.5 to 1.3 (x10-6mm³ / N · m), and shows notable effects compared to other modalities in test 4.

[00067] In the sliding layer, the graphite is preferably greater than or equal to 5% by volume and less than or equal to 30% by volume with respect to all the solid components in the sliding layer. In this case, the sliding layer can further improve wear resistance under the dry environment or under the oily environment. In addition, graphite does not need to be included in the solid lubricant as in the sliding members of modes 16 and 18.

[00068] Although the present invention has been described above,

In line with modalities 1 to 18, it goes without saying that the invention is not limited to the modalities described above 1 to 18, but can still be modified appropriately in the application without departing from the scope of the invention.

[00069] For example, in the present invention, it is possible to carry out the step of degreasing contact with alkali or similar to the base material to increase the adhesion of the base material and the sliding layer. In addition, it is also possible to form an underlying layer formed from phosphate, such as zinc phosphate and manganese phosphate, after the degreasing step to further increase the adhesion of the base material and the sliding layer. Industrial Applicability

[00070] The present invention can be applied to several sliding members. Reference List 2, 5, 6, 7 Corresponding material (2, 7… pin, 5… shoe, 6… ring) 10 Sliding member 20, 30, 40 Base material 10a, 20a, 30a, 40a Sliding layer

Claims (8)

1. Method for manufacturing a sliding member for the manufacture of a sliding member that slides with a corresponding material, characterized by the fact that it comprises: a crosslinking step to irradiate the particulate ultra-high molecular weight polyethylene with radiation rays in a sealed state, and the crosslinking of ultra-high molecular weight polyethylene; a composition preparation step for preparing a composition for a sliding layer containing a solid lubricant that includes the ultra-high molecular weight polyethylene cross-linked in the cross-linking step, and the binder resin; and a sliding layer forming step to form a sliding layer that slides with the corresponding material by providing the composition for a sliding layer in a base material, and obtaining a sliding member. 2. Method for making a sliding member according to claim 1, characterized by the fact that the crosslinking step is carried out under a condition that an absorbed dose of electron beams such as radiation rays is greater than or equal to 60 kGy and less than 500 kGy. 3. Sliding member, characterized by the fact that it comprises a base material, and a sliding layer formed on the base material, and which contains a binder resin and a solid lubricant, the sliding layer that slides with a corresponding material; wherein the solid lubricant includes the cross-linked ultra-high molecular weight polyethylene, which has a melting point that is greater than 126.4 ° C and less than or equal to 132.0 ° C. 4. Sliding member according to claim 3, characterized by the fact that ultra-high molecular weight polyethylene has a gel fraction greater than or equal to 26%. 5. Sliding member, according to claim 3 or 4, characterized by the fact that in the sliding layer, the solid lubricant is greater than or equal to 25% by volume and less than or equal to 100% by volume with respect to resin binder; in the sliding layer, the bonding resin is polyamide-imide; and the ultra-high molecular weight polyethylene is greater than or equal to 5% by volume and less than or equal to 35% by volume with respect to all solid components in the sliding layer. 6. Sliding member, according to claim 5, characterized by the fact that the solid lubricant also includes molybdenum disulfide; and in the sliding layer, the molybdenum disulfide is less than or equal to 26% by volume with respect to all solid components in the sliding layer. 7. Sliding member, according to claim 6, characterized by the fact that in the sliding layer, the ultra-high molecular weight polyethylene is greater than or equal to 23% in volume and less than or equal to 35% in volume with with respect to all solid components in the sliding layer, and molybdenum disulfide is less than or equal to 15% by volume with respect to all solid components in the sliding layer. Sliding member according to any one of claims 5 to 7, characterized by the fact that the solid lubricant also includes graphite; and in the sliding layer, the graphite is greater than or equal to 5% by volume and less than or equal to 30% by volume with respect to all solid components in the sliding layer.