Solid lubricating rolling bearing

Abstract

The present application relates to a solid lubricating rolling bearing, at least one of the outer raceway surface, the inner raceway surface and the surface of the rolling elements being provided with a lubricating coating, the lubricating coating including at least one type of diamond-like carbon-based coating, the diamond-like carbon-based coating including carbon, hydrogen and doping elements, the doping elements including weak carbide-forming metal elements, strong carbide-forming metal elements and non-metal elements; wherein, in the diamond-like carbon-based coating, based on the total amount of atoms of carbon and doping elements, the atomic percentage content of carbon is 70% to 90%, based on the total amount of atoms of the doping elements, the atomic percentage content of the weak carbide-forming metal elements is 50% to 70%, and based on the total amount of atoms of the remaining doping elements except the weak carbide-forming metal elements, the atomic percentage content of the strong carbide-forming metal elements is 50% to 80%. This solid lubricating rolling bearing can achieve ultra-slipping in a low-temperature wide-temperature range and a humid atmosphere.

Description

Technical Field

[0001] The present application relates to the technical field of rolling bearings and solid lubricating coating material preparation, and in particular to a solid lubricating rolling bearing. Background Art

[0002] Rolling bearings are key components of rotating joints in aerospace mechanisms. Failure of rolling bearings directly affects the performance, service life and reliability of the mechanism, and may even lead to failure of the mechanism. At the same time, the low-friction and stable operation of rolling bearings is of great significance to the high-precision operation of the mechanism. Therefore, ensuring the low-friction and stable operation of rolling bearings is crucial to the entire aerospace equipment.

[0003] Rolling bearings are affected by low temperatures during the operation of aerospace equipment, and grease lubrication cannot be used normally. Generally, when the temperature is below -40°C, the friction performance of grease lubrication will be greatly reduced, causing the friction torque of the bearing to rise sharply. Therefore, two methods are often used for the lubrication of space bearings: first, use electronically controlled heating to keep the grease lubrication in the bearing in normal working condition, but this method will greatly increase the complexity of the structure and system, consume a lot of energy, and there is also the risk of lubrication failure caused by power failure; second, use solid lubricating materials with stable lubrication performance in a wide temperature range. At present, international bearing companies and scientific research institutions focus on improving the friction performance of bearings in a vacuum environment. Molybdenum disulfide is usually used as a solid lubricating coating, and is combined with a self-lubricating retainer for lubrication. However, molybdenum disulfide has poor lubrication performance in the atmosphere, low load-bearing capacity, relatively poor mechanical properties, and is prone to wear failure.

[0004] Therefore, how to improve the friction performance of rolling bearings at low temperatures is a key issue that needs to be solved urgently. Summary of the invention

[0005] Based on this, it is necessary to provide a solid lubrication rolling bearing having excellent friction performance at low temperatures.

[0006] In one aspect of the present application, a solid lubrication rolling bearing is provided, comprising:

[0007] An outer ring having an outer raceway surface;

[0008] An inner ring having an inner raceway surface;

[0009] a plurality of rolling elements disposed between the outer raceway surface and the inner raceway surface; and

[0010] A retainer that holds and evenly separates the rolling elements between the inner race and the outer race;

[0011] At least one of the surfaces of the outer raceway surface, the inner raceway surface, and the rolling elements is provided with a lubricating coating;

[0012] The lubricating coating includes at least one type of diamond-like carbon-based coating. The constituent elements of the diamond-like carbon-based coating include carbon, hydrogen, and doping elements. The doping elements include weak carbide-forming metal elements, strong carbide-forming metal elements, and non-metal elements. In the diamond-like carbon-based coating, based on the total amount of carbon and doping elements by atoms, the atomic percentage content of carbon is 70% to 90%. Based on the total amount of doping elements by atoms, the atomic percentage content of the weak carbide-forming metal elements is 50% to 70%. Based on the total amount of the remaining doping elements except the weak carbide-forming metal elements by atoms, the atomic percentage content of the strong carbide-forming metal elements is 50% to 80%.

[0013] In one embodiment, the weak carbide-forming metal element is selected from any one of the following cases:

[0014] (a) Al;

[0015] (b) A combination of Al and Ag;

[0016] (c) A combination of Al and Au;

[0017] (d) A combination of Al and Cu;

[0018] Among them, in (b), (c), and (d), the atomic percentage content of the Al element is 70% to 90%.

[0019] In some embodiments, the strong carbide-forming metal element is selected from at least one of Cr, Ti, or W.

[0020] In some embodiments, the non-metal element is selected from Si.

[0021] In another aspect of the present application, the lubricating coating further includes a substrate bonding layer, a hard strengthening layer, and a gradient layer stacked in sequence. The substrate bonding layer is bonded to the surface of the outer raceway surface, the inner raceway surface, or the rolling elements, and the diamond-like carbon-based coating is disposed on the gradient layer;

[0022] Among them, the material of the hard strengthening layer is a nitride, and the material of the gradient layer is a carbonitride with a gradient change in carbon content and nitrogen content.

[0023] In some embodiments, the solid lubricating rolling bearing further includes at least one of the following technical features:

[0024] The material of the substrate bonding layer is any one of Cr, Ti, AlCrSi, or AlTiSi;

[0025] The material of the hard strengthening layer is a nitride of any one of Cr, Ti, AlCrSi or AlTiSi.

[0026] In some embodiments, from the end close to the hard strengthening layer to the end close to the diamond-like carbon-based coating, the nitrogen content gradient of the gradient layer material decreases to zero, and the carbon content gradient increases to the same as the carbon content in the diamond-like carbon-based coating.

[0027] In some embodiments, the thickness of the diamond-like carbon-based coating is 50% - 80% of the thickness of the lubricating coating.

[0028] In some embodiments, the solid lubricating rolling bearing further includes at least one of the following technical features:

[0029] The thickness of the substrate bonding layer is 300nm - 800nm;

[0030] The thickness of the hard strengthening layer is 100nm - 300nm;

[0031] The thickness of the gradient layer is 100nm - 300nm;

[0032] The thickness of the diamond-like carbon-based coating is 500nm - 2000nm;

[0033] The thickness of the lubricating coating is 800nm - 3μm.

[0034] In some embodiments, the material of the cage is a polyetheretherketone-based composite material;

[0035] The polyetheretherketone-based composite material includes a polyetheretherketone matrix material and fillers. The fillers include a lubricating phase and a reinforcing phase. The lubricating phase is at least one of polytetrafluoroethylene, graphite, graphene, molybdenum disulfide or tungsten disulfide, and the reinforcing phase is at least one of carbon fiber, glass fiber or metal material;

[0036] Based on the total mass of the polyetheretherketone-based composite material, the mass fraction of the polyetheretherketone matrix material is 60% - 90%, and based on the total mass of the fillers, the mass fraction of the lubricating phase is 30% - 70%.

[0037] In some embodiments, the cage is a cage with an outer ring guiding method, the guiding gap is 0.2mm - 0.4mm, the cage has pockets for receiving the rolling elements, and the pocket gap is (1.1 - 1.2) × the diameter of the rolling element.

[0038] In some embodiments, the radial clearance of the solid lubricating rolling bearing is C3 - C5 level.

[0039] Compared with the prior art, the present application has at least the following beneficial effects:

[0040] On at least one surface involving rolling friction in the solid lubricating rolling bearing provided by the present application, a diamond-like carbon-based coating is arranged. By adding metal elements forming weak carbides, metal elements forming strong carbides and non-metal elements in specific proportions in the coating, the coating has excellent friction and mechanical properties, and can achieve stable superlubricity in a wide temperature range at low temperature (down to -80°C).

[0041] In the diamond-like carbon-based coating, the metal elements forming weak carbides can induce the coating to accelerate graphitization, that is, induce the carbon atoms in the coating to be in the sp 2 hybrid structure (graphite structure), so as to obtain a low friction coefficient, reduce the internal stress in the coating and improve its toughness; while the metal elements forming strong carbides can induce the carbon atoms in the coating to be in the sp 3 hybrid structure (diamond structure), so as to obtain high hardness; further, the non-metal elements can combine with water molecules to form hydrates with low shear force, thereby reducing the sensitivity to the humid atmosphere environment; through the synergistic effect of metal elements forming weak carbides, metal elements forming strong carbides and non-metal elements in specific proportions, the diamond-like carbon-based coating can reduce the friction coefficient to the superlubricity level in a wide temperature range at low temperature and in a humid atmosphere environment, and at the same time can also have high hardness.

[0042] The cage of the solid lubricating rolling bearing provided by the present application adopts a PEEK-based self-lubricating cage, which has the characteristics of high strength at low temperature and self-lubricity; the clearances used in the solid lubricating rolling bearing, the cage guiding clearance and the pocket clearance all consider the influence brought by the material shrinkage at low temperature, ensuring that the bearing can still work well at low temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0044] Figure 1 It is a schematic structural diagram of a composite coating according to an embodiment of the present application;

[0045] Figure 2 It is a schematic structural diagram of a solid lubricating rolling bearing according to an embodiment of the present application;

[0046] Figure 3 It is a comparison diagram of the friction coefficients of the assembled bearings in Example 1, Example 2 and Comparative Example 1 of the present application.

[0047] Reference numerals:

[0048] 100: Composite coating

[0049] 110: Substrate bonding layer; 120: Hard strengthening layer; 130: Gradient layer; 140: Friction layer;

[0050] 200: Solid lubricating rolling bearing

[0051] 210: Outer ring; 211: Outer raceway surface; 220: Inner ring; 221: Inner raceway surface; 230: Rolling element; 240: Cage. Detailed implementation manners

[0052] To facilitate the understanding of this application, the following will provide a more comprehensive description of this application with reference to the relevant drawings. The drawings show the preferred embodiments of this application. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of this application more thorough and comprehensive.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the description of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0054] In this document, among the technical features described in an open-ended manner, there are included closed technical solutions composed of the listed features, as well as open technical solutions including the listed features.

[0055] In this document, regarding numerical ranges, unless otherwise specified, the above numerical ranges are considered continuous and include the minimum and maximum values of the range, as well as each value between such minimum and maximum values. Further, when the range refers to integers, it includes each integer between the minimum and maximum values of the range. In addition, when multiple ranges are provided to describe features or characteristics, these ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0056] In this document, regarding the units of data ranges, if the unit is only attached after the right endpoint, it means that the units of the left endpoint and the right endpoint are the same. For example, 0.3~0.5m / s means that the units of the left endpoint "0.3" and the right endpoint "0.5" are both m / s (meters per second).

[0057] This document specifically discloses only some numerical ranges. However, any lower limit can be combined with any upper limit to form a range not explicitly recited; and any lower limit can be combined with other lower limits to form a range not explicitly recited, and similarly any upper limit can be combined with any other upper limit to form a range not explicitly recited. In addition, each individually disclosed point or single numerical value itself can serve as a lower limit or an upper limit and be combined with any other point or single numerical value or with other lower limits or upper limits to form a range not explicitly recited.

[0058] If there is no special instruction, all steps of this application can be carried out sequentially or randomly. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out sequentially, or can also include steps (b) and (a) carried out sequentially. For example, when it is mentioned that the method may further include step (c), it means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b), and (c), or can also include steps (a), (c), and (b), or can also include steps (c), (a), and (b), etc.

[0059] The term "weak carbide-forming metal element" refers to a metal element that has a slightly stronger chemical affinity with carbon than iron, thus forming carbides with relatively poor stability.

[0060] The term "strong carbide-forming metal element" refers to a metal element that has a significantly stronger chemical affinity with carbon than iron, thus forming stable carbides.

[0061] The term "atomic percentage content" refers to the percentage of the number of atoms, that is, the number of atoms of a specific substance accounts for the total number of specified atoms.

[0062] The term "ultra-low friction" means that the friction coefficient is less than 0.01.

[0063] On the one hand, this application provides a diamond-like carbon-based coating, the constituent elements of which include carbon, hydrogen, and doping elements. The doping elements include weak carbide-forming metal elements, strong carbide-forming metal elements, and non-metal elements. In the diamond-like carbon-based coating, based on the total amount of atoms of carbon and doping elements, the atomic percentage content of carbon is 70% to 90%, based on the total amount of atoms of doping elements, the atomic percentage content of weak carbide-forming metal elements is 50% to 70%, and based on the total amount of atoms of the remaining doping elements except weak carbide-forming metal elements, the atomic percentage content of strong carbide-forming metal elements is 50% to 80%.

[0064] In the diamond-like carbon-based coating, weak carbide-forming metal elements mainly exist in the metallic state, strong carbide-forming metal elements mainly exist in the form of metal carbide nanocrystals or metal solid solutions, and non-metal elements mainly exist in the amorphous form.

[0065] Specifically, the diamond-like carbon-based coating is composed of an interpenetrating network. The interpenetrating network includes a diamond-like carbon network composed of carbon connected in the sp 3 form and stabilized by hydrogen atoms, and carbon connected in the sp 2 form, and weak carbide-forming metal elements, strong carbide-forming metal elements, and non-metal elements are respectively distributed in the above interpenetrating network in the form of metal atoms and clusters, metal carbides and solid solutions, and non-metal carbides and amorphous networks.

[0066] In some embodiments, the weak carbide-forming metal element is Al. In some embodiments, the weak carbide-forming metal element is a combination of Al and Ag, and the atomic percentage content of the Al element in the combination of Al and Ag is 70% to 90%. In some embodiments, the weak carbide-forming metal element is a combination of Al and Au, and the atomic percentage content of the Al element in the combination of Al and Au is 70% to 90%. In some embodiments, the weak carbide-forming metal element is a combination of Al and Cu, and the atomic percentage content of the Al element in the combination of Al and Cu is 70% to 90%. The Al element can reduce the internal stress of the material and improve the toughness of the material, and induce the coating to accelerate graphitization.

[0067] In some embodiments, the strong carbide-forming metal element is selected from at least one of Cr, Ti, or W. Cr, Ti, or W can improve the interface matching with steel. Further preferably Cr. The Cr element forms CrC nanocrystals with C to increase the hardness of the coating and make the coating have higher load-bearing capacity.

[0068] In some embodiments, the non-metal element is selected from Si. The low-shear hydrated silica gel formed by the combination of the Si element and water molecules can well improve the friction performance of the coating in a humid atmosphere.

[0069] Furthermore, the strong reaction ability of Al, Cr, and Si elements with oxygen and the indirect protection of the low-shear graphite layer (sp 2 hybridized carbon grid) jointly reduce the sensitivity of the coating to the humid atmosphere environment, making the coating have a lower friction coefficient.

[0070] In some embodiments, the constituent elements of the diamond-like carbon-based coating include C, Si, Al, and Cr. During the friction process, the hydrated silica gel formed by the Si element preferentially combines with the counterbody to form a transfer film, so that the oxidized Al and Cr elements (aluminum oxide, chromium oxide) are separated from the counterbody, and are gradually wrapped by the graphite layer (sp 2 hybridized carbon grid) on the surface layer of the transfer film, effectively reducing friction.

[0071] Please refer to Figure 1 , on the other hand, this application also provides a composite coating 100, including:

[0072] A substrate bonding layer 110 disposed on a substrate 10;

[0073] A hard strengthening layer 120 disposed on the substrate bonding layer 110;

[0074] A gradient layer 130 disposed on the hard strengthening layer 120;

[0075] A friction acting layer 140 disposed on the gradient layer 130.

[0076] The material of the substrate bonding layer 110 has a strong bonding force with the substrate 10. In some embodiments, the material of the substrate bonding layer 110 can be any one of Cr, Ti, AlCrSi or AlTiSi. The thickness of the substrate bonding layer 110 can be any value between 300 nm and 800 nm, for example, it can also be 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm.

[0077] The material of the hard strengthening layer 120 is a nitride, which has a high hardness, can improve the mechanical strength of the composite coating, and plays a role in supporting high loads. In some embodiments, the material of the hard strengthening layer 120 can be a nitride of any one of Cr, Ti, AlCrSi or AlTiSi. Preferably, the material of the hard strengthening layer 120 is a nitride of the corresponding material of the substrate bonding layer 110. For example, when the material of the substrate bonding layer 110 is Cr, the material of the hard strengthening layer 120 is CrN; when the material of the substrate bonding layer 110 is Ti, the material of the hard strengthening layer 120 is TiN; when the material of the substrate bonding layer 110 is AlCrSi, the material of the hard strengthening layer 120 is AlCrSiN; when the material of the substrate bonding layer 110 is AlTiSi, the material of the hard strengthening layer 120 is AlTiSiN. The thickness of the hard strengthening layer 120 can be any value between 100 nm and 300 nm, for example, it can also be 150 nm, 200 nm, 250 nm.

[0078] The material of the gradient layer 130 is a carbonitride with a gradient change in carbon content and nitrogen content. In some embodiments, from the end close to the hard strengthening layer 120 to the end close to the friction acting layer 140 of the gradient layer 130, its nitrogen content gradient drops to zero, and the carbon content gradient increases to the same as the carbon content in the friction acting layer 140. The thickness of the gradient layer 130 can be any value between 100 nm and 300 nm, for example, it can also be 150 nm, 200 nm, 250 nm.

[0079] The friction layer 140 is a diamond-like carbon-based coating of any of the above embodiments. The thickness of the friction layer 140 is at least half of the thickness of the composite coating 100. Specifically, the thickness of the friction layer 120 can be any value between 500 nm and 2000 nm, for example, it can also be 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1000 nm, 1050 nm, 1100 nm, 1150 nm, 1200 nm, 1250 nm, 1300 nm, 1350 nm, 1400 nm, 1450 nm, 1500 nm, 1550 nm, 1600 nm, 1650 nm, 1700 nm, 1750 nm, 1800 nm, 1850 nm, 1900 nm, 1950 nm.

[0080] In some embodiments, the composite coating 100 is composed of a substrate bonding layer 110, a hard strengthening layer 120, a gradient layer 130, and a friction layer 140 that are laminated in sequence.

[0081] In some embodiments, the friction coefficient of the composite coating 100 is not greater than 0.01 at 20°C and a relative humidity of 0.5%; the friction coefficient of the composite coating 100 is not greater than 0.01 at 20°C and a relative humidity of 52%; the friction coefficient of the composite coating 100 is not greater than 0.01 under nitrogen conditions at -80°C.

[0082] In some embodiments, the nano-hardness of the composite coating 100 is not less than 9 GPa. On another aspect of the present application, a method for preparing a composite coating 100 is further improved. At least one of the substrate bonding layer 110, the hard strengthening layer 120, the gradient layer 130, and the friction layer 140 in the composite coating is deposited by high-power pulsed magnetron sputtering. This method has the characteristics of high ionization rate and good wrap-around plating ability, can be more conducive to parametric control of the deposition process, and can be extended to industrial production applications.

[0083] In some embodiments, the sputtering deposition parameters are: pulsed voltage 500 V - 900 V, pulse length 50 μs - 200 μs, pulse frequency 50 Hz - 200 Hz, substrate bias voltage 50 V - 200 V, the substrate bias voltage for preparing the substrate bonding layer is 500 V - 900 V, and the substrate bias voltage for preparing the hard strengthening layer, the gradient layer, and the friction layer is 50 V - 200 V.

[0084] In some specific embodiments, the method for preparing the composite coating 100 includes:

[0085] (a) Placing the substrate to be processed and the target material corresponding to the substrate bonding layer in a pulsed magnetron sputtering device, introducing an inert gas under vacuum conditions, and sputter-depositing the substrate bonding layer;

[0086] (b) Introduce nitrogen gas, increase the air pressure, and sputter-deposit a hard strengthening layer;

[0087] (c) Gradually reduce the nitrogen gas flow rate, and at the same time gradually increase the flow rate of the carbon source gas introduced, increase the air pressure, and sputter-deposit a gradient layer;

[0088] (d) Replace the target with the target of the doped element in the diamond-like carbon-based coating, and sputter-deposit a friction layer.

[0089] In some embodiments, the substrate is pretreated. The pretreatment steps may include conventional pretreatment steps such as solvent cleaning, polishing, and glow cleaning. For example, in step (e), the surface roughness of the substrate is made less than 400 nm by mechanical polishing; in step (f), the polished substrate is ultrasonically cleaned with ethanol, acetone, and deionized water respectively; in step (g), the substrate is placed in a pulsed magnetron sputtering device, an inert gas is introduced, the air pressure is maintained at 1.0 - 2.5 Pa, and the substrate is cleaned under the condition of a bias voltage of 600 - 1000 V.

[0090] In some embodiments, the air pressure in step (a) is 1.0 Pa to 2.5 Pa.

[0091] In some embodiments, the air pressure in step (b) is increased by 0.3 Pa to 0.6 Pa.

[0092] In some embodiments, the air pressure in step (c) is increased by 0.05 Pa to 0.2 Pa.

[0093] In some embodiments, the air pressure in step (d) is increased by 0.2 Pa to 0.4 Pa.

[0094] In some embodiments, in step (a), at a substrate bias voltage of 600 - 1000 V, work for 5 - 10 min to deposit a substrate bonding layer.

[0095] In some embodiments, in step (c), the nitrogen gas flow rate is reduced to zero, and the flow rate of the carbon source gas is increased to be the same as the carbon content in the friction layer.

[0096] Please refer to Figure 2 , on another aspect of the present application, a solid lubricating rolling bearing 200 is further provided, which includes:

[0097] An outer ring 210 having an outer raceway surface 211;

[0098] An inner ring 220 having an inner raceway surface 221;

[0099] A plurality of rolling elements 230 disposed between the outer raceway surface 211 and the inner raceway surface 221; and

[0100] A cage 240 that holds and evenly separates the rolling elements 230 between the inner ring 220 and the outer ring 210.

[0101] The body materials of the outer ring 210, the inner ring 220, and the rolling elements 230 can be any known steel materials, preferably 9Cr18 stainless steel, bearing steel, or other stainless steels with good low-temperature properties.

[0102] At least one of the surfaces of the outer raceway surface 211, the inner raceway surface 221, and the rolling elements 230 is provided with a lubricating coating. In some embodiments, any one of the surfaces of the outer raceway surface 211, the inner raceway surface 221, and the rolling elements 230 is provided with a lubricating coating. Understandably, the outer raceway surface 211 is provided with a lubricating coating, and the surfaces of the inner raceway surface 221 and the rolling elements 230 have no coating or are provided with other coatings; the inner raceway surface 221 is provided with a lubricating coating, and the surfaces of the outer raceway surface 211 and the rolling elements 230 have no coating or are provided with other coatings; the surface of the rolling elements 230 is provided with a lubricating coating, and the outer raceway surface 211 and the inner raceway surface 221 have no coating or are provided with other coatings. In some other embodiments, any two of the surfaces of the outer raceway surface 211, the inner raceway surface 221, and the rolling elements 230 are provided with lubricating coatings. Understandably, the surfaces of the inner raceway surface 221 and the rolling elements 230 are both provided with lubricating coatings, and the outer raceway surface 211 has no coating or is provided with other coatings; the surfaces of the outer raceway surface 211 and the rolling elements 230 are both provided with lubricating coatings, and the inner raceway surface 221 has no coating or is provided with other coatings; the outer raceway surface 211 and the inner raceway surface 221 are both provided with lubricating coatings, and the surface of the rolling elements 230 has no coating or is provided with other coatings. In still some other embodiments, the surfaces of the outer raceway surface 211, the inner raceway surface 221, and the rolling elements 230 are all provided with lubricating coatings.

[0103] The lubricating coating can be a diamond-like carbon-based coating in any of the above embodiments, can also be the composite coating 100 in any of the above embodiments, and further can be other composite coatings containing the diamond-like carbon-based coating in any of the above embodiments.

[0104] Furthermore, the other coating can be an undoped hydrogenated diamond-like carbon-based coating or a composite coating containing an undoped hydrogenated diamond-like carbon-based coating. Understandably, this composite coating can also include a substrate bonding layer 110, a hard strengthening layer 120, and a gradient layer 130, and can also include any known coatings that can improve the interface bonding force and coating performance. Preferably, the undoped hydrogenated diamond-like carbon-based coating is deposited by plasma-assisted chemical vapor deposition.

[0105] Preferably, in the undoped hydrogenated diamond-like carbon-based coating, the percentage content of H atoms is 10% - 40% based on the total atoms of its constituent elements.

[0106] The thickness of the lubricating coating can be any value between 800 nm and 3 μm, such as 850 nm, 900 nm, 950 nm, 1000 nm, 1050 nm, 1100 nm, 1150 nm, 1200 nm, 1250 nm, 1300 nm, 1350 nm, 1400 nm, 1450 nm, 1500 nm, 1550 nm, 1600 nm, 1650 nm, 1700 nm, 1750 nm, 1800 nm, 1850 nm, 1900 nm, 1950 nm, 2000 nm, 2050 nm, 2100 nm, 2150 nm, 2200 nm, 2250 nm, 2300 nm, 2350 nm, 2400 nm, 2450 nm, 2500 nm, 2550 nm, 2600 nm, 2650 nm, 2700 nm, 2750 nm, 2800 nm, 2850 nm, 2900 nm, 2950 nm.

[0107] The thickness of the diamond-like carbon-based coating is 50% - 80% of the thickness of the lubricating coating.

[0108] In some preferred embodiments, coatings are arranged on the surfaces of the outer raceway surface 211, the inner raceway surface 221, and the rolling elements 230. The coatings arranged on the outer raceway surface 211 and the inner raceway surface 221 include at least a diamond-like carbon-based coating, and the coating arranged on the surface of the rolling elements 230 includes at least an undoped hydrogenated diamond-like carbon-based coating.

[0109] The material of the cage 240 can be any resin material. In some preferred embodiments, the cage is prepared from a polyetheretherketone-based composite material. The polyetheretherketone-based composite material includes a polyetheretherketone matrix material and fillers. Among them, the fillers include a lubricating phase and a reinforcing phase. The lubricating phase is selected from at least one of polytetrafluoroethylene, graphite, graphene, molybdenum disulfide, or tungsten disulfide. The reinforcing phase is selected from at least one of carbon fiber, glass fiber, or metal material. In the polyetheretherketone-based composite material, based on the total mass of the polyetheretherketone-based composite material, the mass fraction of the polyetheretherketone matrix material is 60% - 90%, and based on the total mass of the fillers, the mass fraction of the lubricating phase is 30% - 70%. The cage prepared from the polyetheretherketone-based composite material has the characteristics of high strength at low temperature and self-lubrication.

[0110] The cage 240 can be directly injection-molded through an injection molding machine mold or first injection-molded into a rod and then prepared into a shape by machining.

[0111] In some preferred embodiments, the cage 240 is a cage with an outer ring guiding method, and the guiding gap is 0.2 mm - 0.4 mm.

[0112] The retainer 240 has pockets (not shown in the figure) for accommodating the rolling elements 230. In some embodiments, the pocket clearance is (1.1 - 1.2) × the diameter of the rolling element.

[0113] In some embodiments, the radial clearance of the solid lubricating rolling bearing 200 is of class C3 - C5.

[0114] The clearances, retainer guiding clearances, and pocket clearances used in the above solid lubricating rolling bearing 200 all take into account the influence brought by the material shrinkage at low temperatures, which can ensure that the bearing can still work well at low temperatures.

[0115] The following are specific embodiments. The purpose is to further elaborate on the present application to help those skilled in the art and researchers better understand the present application. The relevant technical conditions do not constitute any limitation to the present application. Any form of modification within the scope of the claims of the present application is within the protection scope of the claims of the present application.

[0116] Unless otherwise specified, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods. The instruments are all conventional selections in the art. For the experimental methods without specific conditions noted in the examples, they are carried out under conventional conditions, such as the conditions described in the literature, books, or the methods recommended by the manufacturers.

[0117] Example 1

[0118] 1. Preparation of the lubricating coating

[0119] (1) Substrate pretreatment

[0120] The surface of the substrate is mechanically polished to make its surface roughness between 50 nm and 100 nm, and then the polished substrate is ultrasonically cleaned with ethanol, acetone, and deionized water for 15 min respectively.

[0121] (2) Glow cleaning

[0122] The cleaned substrate is quickly dried and fixed on the bracket inside the coating cavity, and then the vacuum is pumped to a vacuum degree better than 5×10 -3 Pa. At this time, argon is introduced to keep the chamber pressure at 1.4 Pa, the bias power supply is turned on, the bias voltage is set to 900 V, and the working time is 20 min.

[0123] (3) Preparation of the substrate bonding layer

[0124] Select Cr as the target material for the substrate bonding layer, change the gas flow rate of argon to keep the gas pressure in the chamber at 0.45 Pa, turn on the high-power pulsed magnetron sputtering power supply, set its pulsed voltage to 600 V, pulse length to 100 μs, pulse frequency to 200 Hz, set the substrate bias voltage to 800 V, with a working time of 5 min, and the thickness of this layer is 500 nm.

[0125] (4) Preparation of the hard strengthening layer

[0126] Select the same target material as in step (3), keep the gas flow rate of argon unchanged, and simultaneously introduce nitrogen gas, increasing the gas pressure in the chamber to 0.52 Pa. Keep the same settings of the high-power pulsed magnetron sputtering power supply and turn it on, keep the substrate bias voltage at 100 V, with a working time of 3 min, and the thickness of this layer is 200 nm.

[0127] (5) Preparation of the gradient layer

[0128] On the basis of maintaining the working parameters of step (4), gradually reduce the nitrogen gas flow rate to zero, and simultaneously gradually introduce acetylene gas until the gas pressure in the chamber increases to 0.8 Pa, lasting for 3 min in total, and the thickness of this layer is 200 nm.

[0129] (6) Preparation of the friction action layer

[0130] Use AlCrSi composite target 1 (Al:Cr:Si = 6:3:1) as the target material for element doping. Keep the same parameters of the high-power pulsed magnetron sputtering power supply as in step (5), keep the substrate bias voltage unchanged, with a working time of 15 min and a thickness of 1500 nm, then a diamond-like carbon-based coating doped with Al, Cr, and Si elements is obtained. After being detected by an energy spectrometer, the atomic percentages of C, Al, Cr, and Si in this layer are 80 at.%, 12 at.%, 6 at.%, and 2 at.% respectively. It should be noted that the atomic percentages do not include the content of hydrogen atoms.

[0131] 2. Solid lubricating rolling bearing

[0132] (1) The cage is made of a polyetheretherketone-based composite material (German Ensinger PEEK PVX material). Polyetheretherketone is the matrix material with a mass fraction of 70%. The lubricating phases in the filler are polytetrafluoroethylene and graphite with mass fractions of 10% and 10% respectively, and the reinforcing phase in the filler is carbon fiber with a mass fraction of 10%. After mixing the powders of the above materials evenly, they are injection molded into rod materials through a conventional injection molding machine, and then formed by conventional machining. The guiding method is outer ring guiding, the guiding clearance is 0.3 mm, and the pocket clearance is 0.15 mm.

[0133] (2) The inner ring, outer ring and rolling elements are all made of 9GCr18 stainless steel and processed by conventional methods. The lubricating coating is arranged on the outer raceway surface of the outer ring and the inner raceway surface of the inner ring by the method of step 1, and no coating is arranged on the surface of the rolling elements.

[0134] (3) Assemble the inner ring, outer ring, rolling elements and cage, and its radial clearance is at C5 level.

[0135] Example 2

[0136] It is basically the same as the preparation method of Example 1, except that an undoped hydrogenated diamond-like carbon-based coating is arranged on the surface of the rolling elements. The difference in the preparation method of this coating from that of Example 1 lies only in the preparation of the friction action layer. In this step, the high-power pulsed magnetron sputtering power supply is turned off, the substrate bias voltage is increased to 900V, the acetylene flow rate is increased to raise the chamber pressure by 1.0Pa, the working time is 75min, the thickness is 1000nm, the atomic percentage content of hydrogen element is 30%, and the atomic percentage content of carbon element is 70% (calculated based on the total atoms of the coating).

[0137] Comparative Example 1

[0138] It is basically the same as the preparation method of Example 1, except that no coating is arranged on the inner ring, outer ring and rolling elements.

[0139] Test Example

[0140] Take the bearings prepared in Example 1, Example 2 and Comparative Example 1 as samples, and test their friction coefficients in the range of -80°C to 60°C. The test conditions are:

[0141] The test ambient atmosphere is a nitrogen environment, the test bearing model is 61802 (inner diameter 15mm, outer diameter 24mm, thickness 5mm), and the applied load is 60N. Friction coefficient = frictional torque / (radius of the inner ring of the bearing * applied load), and the friction coefficient obtained from this test is calculated from the starting frictional torque.

[0142] The test results are as Figure 3 shown:

[0143] The friction coefficient of the solid lubricating rolling bearing prepared in Example 1 is as low as 0.0015 at the lowest. It has a low and stable friction coefficient (about 0.002) within the low temperature range of -80°C or below. Especially when the temperature is lower than -40°C, its friction coefficient is still relatively stable, showing obvious advantages compared with grease-lubricated bearings.

[0144] The friction coefficient of the solid lubricating rolling bearing prepared in Example 2 is 20% lower than that of Example 1 (the data of Example 2 are not shown in the figure).

[0145] The bearing prepared in Comparative Example 1 uses conventional grease lubrication (Great Wall 7014 wide-temperature aviation grease). In an environment below -40°C, its friction coefficient is much higher than that of the solid-lubricated rolling bearing in Example 1, and even serious jamming occurs at -80°C.

[0146] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0147] The above-described embodiments only represent several implementation manners of the present application, which are convenient for understanding the technical solutions of the present application specifically and in detail, but should not be construed as a limitation on the protection scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are all within the protection scope of the appended claims of the present application. Therefore, the protection scope of the patent of the present application should be subject to the content of the appended claims, and the description and drawings can be used to explain the content of the claims.

Claims

1. A solid superlubricating rolling bearing, characterized in that, It includes: An outer ring with an outer raceway surface; An inner ring with an inner raceway surface; A plurality of rolling elements arranged between the outer raceway surface and the inner raceway surface; and A retainer that holds and evenly separates the rolling elements between the inner ring and the outer ring; At least one of the surfaces of the outer raceway surface, the inner raceway surface, and the rolling elements is provided with a lubricating coating; The lubricating coating includes at least one layer of diamond-like carbon-based coating, and the constituent elements of the diamond-like carbon-based coating include carbon, hydrogen, and doping elements. The doping elements include weak carbide-forming metal elements, strong carbide-forming metal elements, and non-metal elements. In the diamond-like carbon-based coating, based on the total amount of atoms of the constituent elements of the diamond-like carbon-based coating, the atomic percentage content of hydrogen is 10% to 40%, based on the total amount of atoms of carbon and doping elements, the atomic percentage content of carbon is 70% to 90%, based on the total amount of atoms of doping elements, the atomic percentage content of weak carbide-forming metal elements is 50% to 70%, and based on the total amount of atoms of the remaining doping elements except weak carbide-forming metal elements, the atomic percentage content of strong carbide-forming metal elements is 50% to 80%; The diamond-like carbon-based coating is formed by pulsed magnetron sputtering deposition, and the parameters of the pulsed magnetron sputtering deposition are: pulsed voltage 500V to 900V, pulse length 50μs to 200μs, and pulse frequency 50Hz to 200Hz; The thickness of the diamond-like carbon-based coating is 500nm to 2000nm; The nano-hardness of the lubricating coating is not less than 9GPa; For the solid super-lubricating rolling bearing, under the condition of a wide temperature range of -80°C to +60°C, the friction coefficient is not greater than 0.

01.

2. The solid superlubricating rolling bearing according to claim 1, characterized in that, The weak carbide-forming metal element is selected from any one of the following cases: (a) Al; (b) A combination of Al and Ag; (c) A combination of Al and Au; (d) A combination of Al and Cu; Wherein, in (b), (c), and (d), the atomic percentage content of Al element is 70% to 90%.

3. The solid superlubricating rolling bearing according to claim 1, characterized in that, The strong carbide-forming metal element is selected from at least one of Cr, Ti, or W.

4. The solid superlubricating rolling bearing according to claim 1, characterized in that, The non-metal element is selected from Si.

5. The solid superlubricating rolling bearing according to claim 1, characterized in that, The lubricating coating further includes a substrate bonding layer, a hard strengthening layer, and a gradient layer stacked in sequence. The substrate bonding layer is bonded to the surface of the outer raceway surface, the inner raceway surface, or the rolling elements, and the diamond-like carbon-based coating is arranged on the gradient layer; Wherein, the material of the hard strengthening layer is nitride, and the material of the gradient layer is carbonitride with a gradient change in carbon content and nitrogen content.

6. The solid superlubricating rolling bearing according to claim 5, characterized in that, It further includes at least one of the following technical features: The material of the substrate bonding layer is any one of Cr, Ti, AlCrSi, or AlTiSi; The material of the hard strengthening layer is a nitride of any one of Cr, Ti, AlCrSi, or AlTiSi.

7. The solid superlubricating rolling bearing according to claim 5, characterized in that, From the end close to the hard strengthening layer to the end close to the diamond-like carbon-based coating, the nitrogen content gradient of the gradient layer material decreases to zero, and the carbon content gradient increases to the same as the carbon content in the diamond-like carbon-based coating.

8. The solid superlubricating rolling bearing according to claim 5, characterized in that, The thickness of the diamond-like carbon-based coating is 50% to 80% of the thickness of the lubricating coating.

9. The solid superlubricating rolling bearing according to claim 8, characterized in that, It further includes at least one of the following technical features: The thickness of the substrate bonding layer is 300 nm to 800 nm; The thickness of the hard strengthening layer is 100 nm to 300 nm; The thickness of the gradient layer is 100 nm to 300 nm; The thickness of the lubricating coating is 800 nm to 3 μm.

10. The solid superlubricating rolling bearing according to claim 5, wherein, At least one of the substrate bonding layer, the hard strengthening layer, and the gradient layer is formed by pulsed magnetron sputtering deposition.

11. The solid superlubricating rolling bearing according to claim 10, wherein, The parameters of the pulsed magnetron sputtering deposition are: pulsed voltage 500 V to 900 V, pulse length 50 μs to 200 μs, pulse frequency 50 Hz to 200 Hz, the substrate bias voltage for preparing the substrate bonding layer is 500 V to 900 V, and the substrate bias voltage for preparing the hard strengthening layer, the gradient layer, and the diamond-like carbon-based coating is 50 V to 200 V.

12. The solid superlubricating rolling bearing according to claim 1, wherein, The material of the cage is a polyetheretherketone-based composite material; The polyetheretherketone-based composite material includes a polyetheretherketone matrix material and fillers. The fillers include a lubricating phase and a reinforcing phase. The lubricating phase is at least one of polytetrafluoroethylene, graphite, graphene, molybdenum disulfide, or tungsten disulfide, and the reinforcing phase is at least one of carbon fiber, glass fiber, or metal material; Based on the total mass of the polyetheretherketone-based composite material, the mass fraction of the polyetheretherketone matrix material is 60% to 90%, and based on the total mass of the fillers, the mass fraction of the lubricating phase is 30% to 70%.

13. The solid superlubricating rolling bearing according to claim 1, wherein, The cage is a cage with an outer ring guiding method, the guiding gap is 0.2 mm to 0.4 mm, the cage has pockets for accommodating the rolling elements, and the pocket gap is (1.1 to 1.2) × the diameter of the rolling element.

14. The solid superlubricating rolling bearing according to claim 1, wherein, Its radial clearance is C3 to C5 level.

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