A liquid metal lubricated ray tube anode bearing

Abstract

The present invention belongs to the field of bearing technology and relates to a liquid metal-lubricated X-ray tube anode bearing, the X-ray tube anode bearing comprising a fixed sleeve and a sealing end that seals the fixed sleeve; a chamber formed by the fixed sleeve and the sealing end is filled with liquid metal; a flange shaft, a bearing outer ring, and a ball are disposed in the chamber, one end of the flange shaft passes through the sealing end and is located outside the chamber and is connected to the flange; a self-repairing gradient coating is provided on the surface of the bearing outer ring, the surface of the ball, and the surface of the flange shaft; a gap is provided between the sealing end and the flange shaft, and a sealing layer is coated on the outer surface of the flange shaft located in the gap. The X-ray tube anode bearing provided by the present invention has excellent lubricity, corrosion resistance, and sealing properties, and can effectively solve problems such as substrate corrosion, seal failure, and vacuum contamination in high-temperature and high-vacuum environments.

Description

Technical Field

[0001] The present invention relates to the technical field of bearings, and in particular to a liquid metal lubricated ray tube anode bearing. Background Art

[0002] In the field of X-ray tube technology, early X-ray tube anode bearings mostly used ball bearings. However, with the development of medical technology, more and more application scenarios require X-ray tubes to operate under extreme conditions of high temperature and high vacuum. The existing lubrication method has many problems in high temperature and high vacuum environments, such as substrate corrosion, seal failure, and vacuum contamination. These problems seriously restrict the performance and service life of the anode bearings, making it difficult to meet the requirements of modern X-ray tube technology for high-performance bearings.

[0003] Liquid metals, such as gallium-based alloys, not only have a low friction coefficient but also relatively good high-temperature stability. They have been tried for use in X-ray tube anode bearings. However, in practical applications, this lubrication method also faces some drawbacks that need to be addressed: (1) There is no protective coating, and the substrate corrosion problem is serious. The liquid metal is in direct contact with the metal raceway, which can easily cause intergranular corrosion, destroying the integrity and stability of the substrate, and thus affecting the bearing's load capacity and service life; (2) The sealing design is simple, and traditional sealing materials are difficult to effectively prevent the penetration of liquid metal, resulting in liquid metal leakage and affecting the lubrication effect; (3) There is a vacuum contamination problem. Liquid metal is easy to volatilize at high temperatures, and its volatiles will reduce the vacuum degree of the system, affecting the normal operation of the X-ray tube, and may even cause equipment failure.

[0004] Therefore, a new type of liquid metal lubricated X-ray tube anode bearing is needed to solve the problems of substrate corrosion, seal failure, vacuum contamination, etc. existing lubrication methods in high temperature and high vacuum environments, improve the lubrication performance, corrosion resistance and service life of the bearing, and adapt to the application requirements under high temperature and high vacuum conditions. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the purpose of the present invention is to provide a liquid metal-lubricated X-ray tube anode bearing. Compared with the existing technology, the X-ray tube anode bearing provided by the present invention has excellent lubricity, corrosion resistance and sealing performance, and can effectively solve the problems of substrate corrosion, seal failure and vacuum contamination in high-temperature and high-vacuum environments.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] The present invention provides a liquid metal lubricated ray tube anode bearing. The ray tube anode bearing comprises a fixed sleeve and a sealing end for sealing the fixed sleeve.

[0008] The chamber formed by the fixed sleeve and the sealing end is filled with liquid metal.

[0009] A flange shaft, a bearing outer ring and balls are arranged in the chamber. One end of the flange shaft passes through the sealing end and is located outside the chamber and is connected to the flange; the bearing outer ring is sleeved on the outer circumference of the flange shaft, and balls are arranged at the connection between the bearing outer ring and the flange shaft.

[0010] The surface of the bearing outer ring, the surface of the ball and the surface of the flange shaft are all provided with a self-repairing gradient coating; the self-repairing gradient coating includes a CrAlN transition layer, a TiB2 functional layer and a MAX phase ceramic surface layer stacked in sequence from the substrate surface to the outside.

[0011] A gap is set between the sealing end and the flange shaft, and a sealing layer is coated on the outer surface of the flange shaft located at the gap.

[0012] The X-ray tube anode bearing provided by the present invention improves existing bearings in three main aspects. First, a self-repairing gradient coating is provided, and a coating is plated on bearing parts (such as the surface of the bearing outer ring, the surface of the ball, and the surface of the flange shaft) to prevent liquid metal from penetrating the matrix and achieve surface self-repair. Second, a sealing layer is provided to provide a new sealing structure that is resistant to high temperatures and liquid metal infiltration. Third, the selection of a specifically formulated liquid metal can further enhance the lubrication effect, facilitate the formation of a stable lubrication layer through tribochemical reactions, and reduce the friction coefficient.

[0013] Preferably, the balls include two groups symmetrically arranged along a straight line perpendicular to the flange axis, one group of balls is arranged at the proximal flange end, and the other group is arranged at the distal flange end, and each group of balls is distributed in a ring shape around the circumference of the flange axis.

[0014] Preferably, the sealing end faces one side of the flange shaft, and sealing positions are arranged at intervals along the axial direction of the flange shaft.

[0015] Preferably, the sealing portion is in the shape of a groove.

[0016] In the present invention, when the seal is not tight and liquid metal leaks, the groove-shaped sealing position can temporarily store the liquid metal, thereby preventing it from leaking further.

[0017] Preferably, the gap between the sealing end and the flange shaft is 0.10-0.25 mm, for example, it can be 0.1 mm, 0.12 mm, 0.14 mm, 0.16 mm, 0.18 mm, 0.2 mm, 0.22 mm, 0.24 mm or 0.25 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] In the present invention, controlling the gap between the sealing end and the flange shaft within a specific range can effectively prevent liquid metal leakage. When the gap is too small, sliding friction between the sealing end and the flange shaft is likely to occur. When the gap is too large, sealing failure is likely to occur.

[0019] Preferably, the MAX phase ceramic surface layer includes a Ti3SiC2 layer and / or a Ti2AlC layer.

[0020] In the self-repairing gradient coating provided by the present invention, the CrAlN transition layer adopts ion bombardment to form a metallurgical bond, which can enhance the bonding force between the CrAlN transition layer and the substrate and inhibit the diffusion of liquid metal along the grain boundaries of the substrate; the TiB2 functional layer is a high-hardness (3000HV) bearing layer, which can block liquid metal and provide a wear-resistant surface that can bear friction loads; the MAX phase ceramic surface layer can effectively self-repair the interface.

[0021] Furthermore, when the MAX phase ceramic surface layer adopts a Ti3SiC2 layer, the Ti3SiC2 layer contains a layered structure. When friction damage occurs on the surface layer, micro-repair of the surface is achieved through interlayer slippage, continuously blocking the penetration of liquid metal. The Ti3SiC2 layer is decomposed into nano-scale active species such as TiC and Si through stress induction under high temperature and high vacuum conditions. When nano-TiB2 is added to the liquid metal, a TiB2-TiC-Si composite lubricating film can be generated through solid-phase diffusion, thereby reducing the friction coefficient; when the MAX phase ceramic surface layer adopts a Ti2AlC layer, the Ti2AlC layer will decompose into TiC and Al elements under the action of friction stress. When the liquid metal contains TiB2, Al and TiB2 in the liquid metal are mechanically mixed in a non-oxidizing environment to generate a TiB2-Al2O3 composite lubricating film, thereby achieving self-repair. The shear strength of the TiB2-Al2O3 composite lubricating film is 0.3-0.6GPa, and the friction coefficient μ≤0.07.

[0022] In the present invention, the preparation methods of the CrAlN transition layer, TiB2 functional layer, Ti3SiC2 layer, and Ti2AlC layer can adopt conventional preparation methods in the art, for example, the following methods can be specifically adopted:

[0023] In the present invention, the CrAlN transition layer is prepared by a multi-arc ion plating method, using a Cr-Al alloy target (wherein Cr accounts for 70wt% and Al accounts for 30wt%), an arc current of 80-120A, an argon flow rate of 40-60sccm, a nitrogen flow rate of 10-20sccm, a bias voltage of -80 to -150V, and a deposition time of 20-30min.

[0024] In the present invention, the TiB2 functional layer is deposited by radio frequency magnetron sputtering using a pure TiB2 target (purity ≥99.5%, diameter 50-100 mm, thickness 5-10 mm, sintered density ≥95%), sputtering power 300-500 W, argon flow rate 50-80 sccm, bias voltage -100 to -200 V, and deposition time 40-60 min.

[0025] In the present invention, the Ti3SiC2 layer is prepared by plasma enhanced chemical vapor deposition (PECVD), the gas source is TiCl4, CH4, SiH4 and Ar, the temperature is 650-750°C, the pressure is 0.5-1.0 Pa, the TiCl4 flow rate is 10-20sccm, the SiH4 flow rate is 10-20sccm, the CH4 flow rate is 20-30sccm, the Ar flow rate is 70-80sccm, and the deposition time is 15-20min.

[0026] In the present invention, the Ti2AlC layer is prepared by plasma enhanced chemical vapor deposition (PECVD), and the raw materials include TiCl4, AlCl3, CH4 and Ar (carrier gas), wherein TiCl4 is gaseous with a purity of ≥99.9%, AlCl3 is solid and needs to be introduced in gaseous form after sublimation, CH4 has a purity of ≥99.99%, Ar is used as a carrier gas with a purity of ≥99.99%, the deposition temperature is 650-850°C, preferably 750°C, the plasma power is 150-250W, the CH4 flow rate is 15-30sccm, the AlCl3 flow rate is 0.5-1.0sccm, the TiCl4 flow rate is 1.0-2.0sccm, the Ar flow rate is 80-120sccm, the pressure is 20-60Pa, and the deposition time is 20-30min. It should be noted that in the present invention, by controlling the flow rate ratio of TiCl4 and AlCl3 to ensure the stoichiometric ratio, Ti2AlC forms a preferred orientation of the (0002) crystal plane, and the interlayer spacing measured by XRD is 1.02nm, the surface roughness Ra≤0.3μm, and the microhardness is 1800-2200HV.

[0027] Preferably, the thickness of the CrAlN transition layer is 5-8 μm, for example, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm or 8 μm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0028] Preferably, the thickness of the TiB2 functional layer is 10-15 μm, for example, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm or 15 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] Preferably, the thickness of the Ti3SiC2 layer is 2-3 μm, for example, 2 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm or 3 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0030] Preferably, the thickness of the Ti2AlC layer is 2-4 μm, for example, it can be 2 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm, 3 μm, 3.2 μm, 3.4 μm, 3.6 μm, 3.8 μm or 4 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] Preferably, the sealing layer includes a CoCrFeNiAl high entropy alloy layer and / or a FeCoNiCrMo high entropy alloy layer.

[0032] The CoCrFeNiAl high-entropy alloy layer provided by the present invention has a dense nanocrystalline structure, which significantly extends the liquid metal diffusion path and reduces the diffusion coefficient by 2-3 orders of magnitude compared to single-element pure metals (Co, Cr, Fe, Ni, Al, etc.). It is worth noting that the surface energy of the CoCrFeNiAl high-entropy alloy is 380-420mN / m, while the surface energy of liquid metal gallium-based alloy is 550mN / m. It can be seen that the surface energy of the CoCrFeNiAl high-entropy alloy is significantly lower than that of the liquid metal. Therefore, the liquid metal forms a non-wetting state on the surface of the sealing layer, and the sealing layer can inhibit the penetration of the liquid metal, thereby forming a non-contact seal with good sealing effect.

[0033] The FeCoNiCrMo high entropy alloy layer provided by the present invention has a composite structure of nanocrystalline and amorphous. The Mo element contained therein inhibits grain growth. The surface energy of the FeCoNiCrMo high entropy alloy is about 360-400mN / m. It can be seen that the surface energy of the FeCoNiCrMo high entropy alloy is also significantly lower than that of the liquid metal. The contact angle between the high entropy alloy and the liquid metal is greater than 120°, thereby achieving non-wetting sealing, and the sealing effect is good. In addition, the multi-component lattice distortion in the FeCoNiCrMo high entropy alloy layer provided by the present invention causes the diffusion coefficient of liquid metal atoms to be reduced by 4-5 orders of magnitude (compared to single-element pure metal). Mo atoms (with larger atomic radius) fill the lattice gaps and hinder the penetration of Ga, In, and Sn atoms, so that the corrosion resistance of the FeCoNiCrMo high entropy alloy layer is improved by more than 20% compared to the CoCrFeNiAl high entropy alloy layer.

[0034] In the present invention, the CoCrFeNiAl high entropy alloy layer and the FeCoNiCrMo high entropy alloy layer are prepared by multi-arc ion plating, for example, the following method can be used:

[0035] In the present invention, the CoCrFeNiAl high entropy alloy layer adopts a CoCrFeNiAl alloy target (atomic ratio of 1:1:1:1:1, purity ≥99%), an arc current of 60-100A, an argon flow rate of 30-50sccm, a substrate bias of -100 to -200V, a deposition temperature of 25-200°C, a deposition time of 40-60min, and a deposition rate of 0.3-0.5μm / min. In the present invention, the grain size is controlled to be less than 100nm by regulating the deposition rate.

[0036] In the present invention, the FeCoNiCrMo high entropy alloy layer adopts a FeCoNiCrMo alloy target (atomic ratio of 1:1:1:1:1, purity ≥99%), the arc current is 60-100A, preferably 80A, which is beneficial to reducing the splash loss of Mo element, the argon flow rate in the cleaning stage is 30-50sccm, the argon flow rate in the deposition stage is 20-30sccm, the substrate bias voltage is -150 to -250V, the deposition temperature is 25-250°C, the deposition time is 50-70min, and the deposition rate is 0.3-0.5μm / min.

[0037] Preferably, the thickness of the CoCrFeNiAl high entropy alloy layer is 20-30 μm, for example, it can be 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm or 30 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0038] Preferably, the grain size of the CoCrFeNiAl high entropy alloy layer is less than 100 nm, for example, it can be 95 nm, 90 nm, 85 nm, 80 nm, 75 nm or 70 nm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0039] Preferably, the grain boundary density of the CoCrFeNiAl high entropy alloy layer is greater than 2×10 7 m -1 , for example, it can be 2.2×10 7 m -1 , 2.4×10 7 m -1 , 2.6×10 7 m -1 or 2.8×10 7 m -1 , but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable.

[0040] Preferably, the grain size of the FeCoNiCrMo high entropy alloy layer is 50-150 nm, for example, it can be 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm or 150 nm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] Preferably, the grain boundary density of the FeCoNiCrMo high entropy alloy layer is (1.33-6.0)×10 7 m -1 , for example, it can be 1.4×10 7 m -1 , 1.6×10 7 m -1 , 1.8×10 7 m -1 , 2.0×10 7 m -1 , 3.0×10 7 m -1 , 4.0×10 7 m -1 , 5.0×10 7 m -1 or 6.0×10 7 m -1 , but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable.

[0042] Preferably, the thickness of the FeCoNiCrMo high entropy alloy layer is 25-35 μm, for example, it can be 25 μm, 26 μm, 28 μm, 30 μm, 32 μm, 34 μm or 35 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0043] Preferably, the sealing layer and the liquid metal are sealed in a non-contact manner.

[0044] Preferably, the liquid metal includes a base liquid and additives.

[0045] Preferably, the base liquid comprises a gallium-indium-tin alloy.

[0046] In the present invention, the base liquid is made of gallium indium tin alloy (Ga 67 In 20 Sn 13 , melting point is 10.7℃).

[0047] Preferably, the additive includes nano-TiB2 and / or WS2 nanotubes modified with a silane coupling agent.

[0048] In the present invention, when the self-repairing gradient coating contains a Ti3SiC2 layer, it is placed under high temperature and high vacuum conditions, generally at a temperature of 200-400°C and a vacuum degree of 10 -5 Pa, decomposed into nano-scale active species such as TiC and Si through stress induction. In the present invention, by preferably adding nano-TiB2 to the liquid metal, it can form a TiB2-TiC-Si composite lubricating film with active species through solid phase diffusion, which is generally 20-50nm thick. On the one hand, Si atoms can be embedded in the TiB2 lattice to form a low shear strength solid solution with a shear strength of 0.2-0.5GPa, reducing the friction coefficient. On the other hand, TiB2 nanoparticles can be used to fill the micro-pits of the friction pair to form "nano-balls", which convert sliding friction into rolling friction and further enhance the lubrication effect. In addition, the unreacted Ti3SiC2 continues to dissociate to supplement the active species, dynamically generate a new lubricating phase with TiB2, fill the wear pits, and realize the "damage-reaction-repair" cycle. It should be noted that in this process, TiB2, TiC, and Si are all low vapor pressure substances, that is, the vapor pressure at 400°C is less than 10 -6 Pa, no risk of volatile contamination, meeting the ultra-high vacuum requirements of X-ray tubes. When the self-healing gradient coating contains a Ti2AlC layer, the Ti2AlC layer decomposes into TiC and Al elements under the action of friction stress. When the liquid metal contains TiB2, Al and the TiB2 in the liquid metal mechanically mix in a non-oxidizing environment to form a TiB2-Al2O3 composite lubricating film, achieving self-healing. The shear strength is 0.3-0.6GPa, thereby reducing the friction coefficient and improving the lubrication effect.

[0049] In the present invention, adding WS2 nanotubes modified with silane coupling agent to liquid metal can enhance the interfacial bonding between liquid metal and the surface of bearing parts, significantly improving the lubrication performance and stability under extreme working conditions.

[0050] Preferably, the mass of the nano-TiB2 accounts for 5-8% of the base liquid, for example, it can be 5%, 5.2%, 5.5%, 5.8%, 6%, 6.2%, 6.5%, 6.8%, 7%, 7.2%, 7.5%, 7.8% or 8%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0051] Preferably, the particle size of the nano-TiB2 is 50-100 nm, for example, it can be 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm or 100 nm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0052] Preferably, the mass of the WS2 nanotubes accounts for 0.5-1.5% of the base liquid, for example, it can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4% or 1.5%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0053] Preferably, the diameter of the WS2 nanotube is 50-200 nm, for example, it can be 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm or 200 nm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0054] In the present invention, the preparation method of the silane coupling agent modified WS2 nanotubes can be prepared by conventional methods in the art, such as using an ethanol solution of a silane coupling agent (KH-550, concentration 1-3 wt%) and WS2 nanotubes for surface modification reaction, ultrasonic dispersion for 40-50 minutes, to obtain modified WS2 nanotubes. Then, the modified WS2 nanotubes and liquid metal are stirred in a vacuum at 80-100°C for 2-4 hours (vacuum degree is 10 -2 Pa).

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] (1) In the X-ray tube anode bearing provided by the present invention, by providing a self-repairing gradient coating, that is, coating the bearing parts (such as the surface of the bearing outer ring, the surface of the ball and the surface of the flange shaft), it is possible to block the penetration of liquid metal and avoid the corrosion problem of the bearing parts. In addition, when slight wear occurs on the surface of the bearing parts, the gradient coating can automatically repair the defects, reducing the risk of causing further wear and failure, extending the service life of the bearing and improving the operating stability.

[0057] (2) The sealing layer provided in the anode bearing of the ray tube provided by the present invention has good high temperature resistance. When the bearing is in a high temperature working state, it will not cause performance degradation, ensuring the reliability of the seal, preventing liquid metal leakage, and being able to effectively resist liquid metal infiltration, thereby improving the service life and reliability of the bearing.

[0058] (3) In the X-ray tube anode bearing provided by the present invention, by specifically setting the composition of the liquid metal, an in-situ lubricating film can be formed to provide effective lubrication, reduce friction and wear between bearing parts, and the lubricating film can reduce the friction coefficient between bearing parts, further improve the operating stability and reliability of the bearing, and extend its service life.

[0059] (4) The liquid metal lubricated ray tube anode bearing provided by the present invention is at a temperature of 400°C and a vacuum degree of 10 - 5 Pa, tested under the conditions of anode speed of 8000rpm, the corrosion deadlock time is greater than 500h, there is no obvious corrosion, SEM observation shows no grain boundary penetration, the friction coefficient of the bearing parts is 0.04-0.07, the liquid metal leakage is less than 0.6μL / 100h, and the contact angle is 142-155°. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 It is a schematic cross-sectional structural diagram of a liquid metal lubricated X-ray tube anode bearing provided in Example 1 of the present invention.

[0061] Figure 2 This is a partial enlarged view of point A in the liquid metal lubricated X-ray tube anode bearing provided by Example 1 of the present invention.

[0062] Among them, 1-fixed sleeve; 2-sealing end; 3-flange shaft; 4-flange; 5-bearing outer ring; 6-ball; 7-sealing position; 8-sealing layer. DETAILED DESCRIPTION

[0063] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0064] Example 1

[0065] This embodiment provides a liquid metal lubricated ray tube anode bearing, such as Figure 1 and Figure 2 As shown, the anode bearing of the X-ray tube includes a fixed sleeve 1 and a sealing end 2 for sealing the fixed sleeve 1 , and a chamber formed by the fixed sleeve 1 and the sealing end 2 is filled with liquid metal.

[0066] A flange shaft 3, a bearing outer ring 5 and balls 6 are arranged in the chamber. One end of the flange shaft 3 passes through the sealing end 2 and is located outside the chamber, and is connected to the flange 4; the bearing outer ring 5 is sleeved on the outer circumference of the flange shaft 3, and balls 6 are arranged at the connection between the bearing outer ring 5 and the flange shaft 3. The balls 6 include two groups symmetrically arranged along a straight line perpendicular to the flange shaft 3, one group of balls 6 is arranged at the near flange 4 end, and the other group is arranged at the far flange 4 end. Each group of balls 6 is distributed in a ring shape around the circumference of the flange shaft 3. The sealing end 2 faces the side of the flange shaft 3, and groove-shaped sealing positions 7 are arranged at intervals along the axial direction of the flange shaft 3. The gap between the sealing end 2 and the flange shaft 3 is 0.15mm.

[0067] The surface of the bearing outer ring 5, the surface of the ball 6 and the surface of the flange shaft 3 are all provided with a self-repairing gradient coating; a gap is set between the sealing end 2 and the flange shaft 3, and the outer surface of the flange shaft 3 located at the gap is coated with a sealing layer 8.

[0068] In this embodiment, the self-repairing gradient coating includes a CrAlN transition layer, a TiB2 functional layer and a Ti3SiC2 layer stacked in sequence from the surface of the substrate outward; the thickness and preparation method are shown in Table 1.

[0069] Table 1

[0070] In this embodiment, the sealing layer is a CoCrFeNiAl high entropy alloy layer with a thickness of 25 μm, a grain size of 80 nm, and a grain boundary density of 3.75×10 7 m -1 The preparation method is as follows: using CoCrFeNiAl alloy target (atomic ratio of 1:1:1:1:1, purity ≥99%), arc current of 90A, argon flow rate of 40sccm, substrate bias of -120V, deposition temperature of 200℃, deposition time of 50min, and deposition rate of 0.5μm / min.

[0071] In this embodiment, the liquid metal is a gallium indium tin alloy (Ga 67 In 20 Sn 13 , melting point is 10.7 ° C) as the base liquid, and add 5% by mass of nano-TiB2, the particle size of the nano-TiB2 is 60-90nm.

[0072] Example 2

[0073] This embodiment provides a liquid metal lubricated X-ray tube anode bearing. The only difference compared with Example 1 is that the Ti3SiC2 layer in the self-repairing gradient coating is replaced by a Ti2AlC layer of equal thickness, as shown in Table 2.

[0074] Table 2

[0075] Example 3

[0076] This embodiment provides a liquid metal lubricated ray tube anode bearing, which differs from the first embodiment only in that the CoCrFeNiAl high entropy alloy layer in the sealing layer is replaced with a FeCoNiCrMo high entropy alloy layer of equal thickness.

[0077] In this embodiment, the grain size of the FeCoNiCrMo high entropy alloy layer is 50 nm, and the grain boundary density is 6.0×10 7 m -1The preparation method is as follows: using FeCoNiCrMo alloy target (atomic ratio of 1:1:1:1:1, purity ≥99%), arc current of 90A, argon flow rate of 40sccm in the cleaning stage, argon flow rate of 25sccm in the deposition stage, substrate bias of -200V, deposition temperature of 150℃, deposition time of 55min, and deposition rate of 0.4μm / min.

[0078] Example 4

[0079] This embodiment provides a liquid metal-lubricated X-ray tube anode bearing. The only difference compared with Example 1 is that the nano-TiB2 in the liquid metal is replaced by WS2 nanotubes modified with a silane coupling agent, accounting for 0.8% by mass, and the diameter of the WS2 nanotubes is 60-100 nm.

[0080] In this embodiment, the preparation method of the silane coupling agent modified WS2 nanotubes includes: using an ethanol solution of a silane coupling agent (KH-550, concentration 2wt%) and WS2 nanotubes for surface modification reaction, ultrasonic dispersion for 45 minutes, to obtain modified WS2 nanotubes. Then, the modified WS2 nanotubes and liquid metal are stirred in a vacuum at 100°C for 3 hours (vacuum degree is 10 - 2 Pa).

[0081] Example 5

[0082] This embodiment provides a liquid metal lubricated X-ray tube anode bearing, which is different from the first embodiment only in that nano-TiB2 is not added to the liquid metal.

[0083] Comparative Example 1

[0084] This comparative example provides a liquid metal lubricated X-ray tube anode bearing, which differs from Example 1 only in that the self-repairing gradient coating is not provided.

[0085] Comparative Example 2

[0086] This comparative example provides a liquid metal lubricated ray tube anode bearing, which differs from Example 1 only in that no sealing layer is provided and only mechanical sealing is used.

[0087] Performance testing:

[0088] The liquid metal lubricated anode bearings of the X-ray tubes provided in the above embodiments and comparative examples were heated to 400°C and vacuum to 10 -5 The test was carried out under the conditions of Pa and anode rotation speed of 8000 rpm.

[0089] The corrosion blocking time and whether failure or corrosion occurred in Examples 1-4 and Comparative Example 1 are shown in Table 3.

[0090] The friction coefficients of the bearing parts in Example 1, Example 4 and Example 5 under the above working conditions are compared, and the results are shown in Table 4.

[0091] In Example 1, Example 3, and Comparative Example 2, the amount of liquid metal leakage and the contact angle between the sealing surface of the component and the liquid metal were tested. The results are shown in Table 5. When the contact angle is less than 90°, the liquid metal is lyophilic and can spread well. When the contact angle is greater than 90°, the liquid metal is not easily spread, and has a dewetting effect.

[0092] Table 3

[0093] Table 4

[0094] Table 5

[0095] The following points can be seen from Table 3-5:

[0096] (1) From the data of Examples 1-4, it can be seen that the liquid metal lubricated X-ray tube anode bearing provided by the present invention has a corrosion seizure time of more than 500 hours under optimal conditions, no obvious corrosion, no grain boundary penetration observed by SEM, a friction coefficient of 0.04-0.07 for the bearing parts, a liquid metal leakage of less than 0.6 μL / 100 hours, a contact angle of 142-155°, good service life and lubricity, and good sealing effect.

[0097] (2) It can be seen from the data of Example 1 and Example 5 that the present invention can form an in-situ lubricating film by preferably adding nano-TiB2 to the liquid metal base liquid, thereby improving lubricity and reducing the friction coefficient.

[0098] (3) It can be seen from the data of Example 1 and Comparative Example 1 that the present invention can effectively prevent liquid metal penetration, avoid substrate corrosion, and improve the service life of the bearing by providing a self-repairing gradient coating.

[0099] (4) It can be seen from the data of Example 1 and Comparative Example 2 that the present invention can achieve good sealing at high temperatures and resist liquid metal infiltration by providing a sealing layer.

[0100] In summary, the X-ray tube anode bearing provided by the present invention has good lubricity, corrosion resistance and sealing properties, and can effectively solve the problems of substrate corrosion, sealing failure and vacuum pollution in high-temperature and high-vacuum environments.

[0101] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A liquid metal lubricated X-ray tube anode bearing, characterized in that: The ray tube anode bearing includes a fixed sleeve and a sealing end sealing the fixed sleeve; The chamber formed by the fixed sleeve and the sealing end is filled with liquid metal; The chamber is provided with a flange shaft, a bearing outer ring and a ball bearing. One end of the flange shaft passes through the sealing end and is located outside the chamber and is connected to the flange. The bearing outer ring is sleeved on the outer circumference of the flange shaft, and a ball bearing is provided at the connection between the bearing outer ring and the flange shaft. The surface of the bearing outer ring, the surface of the ball and the surface of the flange shaft are all provided with a self-repairing gradient coating; the self-repairing gradient coating comprises a CrAlN transition layer, a TiB2 functional layer and a MAX phase ceramic surface layer stacked in sequence from the substrate surface to the outside; A gap is set between the sealing end and the flange shaft, and a sealing layer is coated on the outer surface of the flange shaft located at the gap.

2. The liquid metal lubricated X-ray tube anode bearing according to claim 1, characterized in that: The balls include two groups symmetrically arranged along a straight line perpendicular to the flange axis, one group of balls is arranged at the proximal flange end, and the other group is arranged at the distal flange end. The balls in each group are distributed in an annular shape around the circumference of the flange axis.

3. The liquid metal lubricated X-ray tube anode bearing according to claim 1, characterized in that: The sealing end faces the side of the flange shaft, and sealing positions are arranged at intervals along the axial direction of the flange shaft; The sealing position is in the shape of a groove; The gap between the sealing end and the flange shaft is 0.10-0.25 mm.

4. The liquid metal lubricated X-ray tube anode bearing according to claim 1, characterized in that: The MAX phase ceramic surface layer includes a Ti3SiC2 layer and / or a Ti2AlC layer.

5. The liquid metal lubricated X-ray tube anode bearing according to claim 4, characterized in that: The thickness of the CrAlN transition layer is 5-8 μm; The thickness of the TiB2 functional layer is 10-15 μm; The thickness of the Ti3SiC2 layer is 2-3 μm; The thickness of the Ti2AlC layer is 2-4 μm.

6. The liquid metal lubricated X-ray tube anode bearing according to claim 1, characterized in that: The sealing layer includes a CoCrFeNiAl high entropy alloy layer and / or a FeCoNiCrMo high entropy alloy layer.

7. The liquid metal lubricated X-ray tube anode bearing according to claim 6, characterized in that: The thickness of the CoCrFeNiAl high entropy alloy layer is 20-30 μm; The grain size of the CoCrFeNiAl high entropy alloy layer is less than 100 nm; The grain boundary density of the CoCrFeNiAl high entropy alloy layer is greater than 2×10 7 m -1 ; The grain size of the FeCoNiCrMo high entropy alloy layer is 50-150 nm; The grain boundary density of the FeCoNiCrMo high entropy alloy layer is (1.33-6.0)×10 7 m -1 ; The thickness of the FeCoNiCrMo high entropy alloy layer is 25-35 μm.

8. The liquid metal lubricated X-ray tube anode bearing according to claim 1, characterized in that: The sealing layer and the liquid metal are sealed in a non-contact manner.

9. The liquid metal lubricated X-ray tube anode bearing according to claim 1, characterized in that: The liquid metal includes a base liquid and additives; The base liquid includes a gallium-indium-tin alloy; The additives include nano-TiB2 and / or WS2 nanotubes modified by a silane coupling agent.

10. The liquid metal lubricated X-ray tube anode bearing according to claim 9, characterized in that: The mass of the nano-TiB2 accounts for 5-8% of the base liquid; The particle size of the nano-TiB2 is 50-100 nm; The mass of the WS2 nanotubes accounts for 0.5-1.5% of the base liquid; The diameter of the WS2 nanotube is 50-200 nm.

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