Method for improving self-lubricating performance of titanium alloy knuckle bearing

Abstract

The invention provides a method for improving the self-lubricating property of a titanium alloy material, which comprises the step of preparing a nano lubricating layer on the surface of a titanium alloy matrix subjected to ion implantation and thermal oxidation modification in an ion beam assisted deposition manner. The zirconium ion implantation layer, the zirconium oxide ceramic layer and the nanometer lubricating film are combined to form a gradient transition, stable and compact multi-layer structure, collaborative optimization of surface hardness and lubricating performance is achieved through the composite multi-layer structure design, the material has excellent self-lubricating performance, and the service life of the material is prolonged. The excellent low-friction and high-wear-resistance effects are shown under the heavy-load and high-friction conditions. According to the method, the durability of the titanium alloy joint bearing under the high-friction working condition can be remarkably improved, and the application field of the titanium alloy joint bearing can be effectively widened.

Description

Technical Field

[0001] The invention relates to a metal surface treatment method, in particular to a method for improving the self-lubricating performance of a titanium alloy spherical bearing. Background Art

[0002] Titanium and its alloys have been widely used in key fields such as aerospace, military weapons, and biomedicine due to their light density, excellent specific strength, and outstanding corrosion resistance. Among them, titanium alloy spherical bearings, as a key functional component, are particularly suitable for high-load, corrosion-resistant, and weight-sensitive working conditions. Although titanium alloys have many advantages, the low hardness, high friction coefficient, and insufficient wear resistance on their surfaces severely limit the long-term stability and service life of titanium alloy spherical bearings in friction environments.

[0003] In view of the application requirements of titanium alloy spherical bearings, it is particularly important to enhance the friction reduction and wear resistance of the surface. At present, the research on the wear resistance strengthening process of titanium alloy is relatively comprehensive and in-depth. The wear resistance of titanium alloy is improved through surface modification and strengthening process. The research on titanium alloy surface strengthening technology mainly focuses on strengthening process methods and improving the organization and mechanical properties.

[0004] For example, CN115232997A provides a method for improving the oxidation resistance and corrosion resistance of titanium alloy by adding metal zirconium. However, adding a large amount of metal zirconium to the alloy may affect the overall mechanical properties of the titanium alloy, such as strength and toughness. In addition, the addition of high-content zirconium is also relatively expensive, and it is difficult to accurately control the thickness and uniformity of the oxide film during high-temperature oxidation treatment.

[0005] CN116837318A provides a titanium alloy surface friction reduction, anti-wear composite treatment method, using photosensitive blue oil as an anti-etching agent, using wet etching technology to process micro-texture on the titanium alloy surface, and thermally oxidizing the textured titanium alloy to obtain a titanium alloy with composite morphology treatment. Wet etching requires precise control of the concentration of the corrosive agent and the processing time, the process is relatively complicated, and the uniformity and controllability of the surface micro-texture are difficult to ensure. At the same time, wet processing has a greater impact on the environment and is not conducive to large-scale application.

[0006] CN118147571A provides a treatment method for enhancing the wear resistance of titanium alloy surface. By using a titanium alloy substrate of a specific type and specific hardness, an oxide layer is formed on the titanium alloy surface, and a highly wear-resistant titanium alloy can be prepared at a heat treatment temperature of less than 700°C. Although low thermal oxidation treatment can reduce the thickness of the oxide layer, the wear resistance is limited, and the oxide film is easy to peel off when used at high temperatures, affecting the long-lasting wear resistance. This method also fails to solve the need for surface self-lubrication.

[0007] CN112483549A provides a self-lubricating spherical bearing and its preparation method, because the bearing inner ring and the bearing outer ring are made of ceramic, and are coated with a diamond-like composite coating at the same time. However, the ceramic material is expensive and difficult to process, which limits its application; the diamond-like coating has very high requirements for the coating process, and may peel off under high temperature and impact load, which significantly affects the wear resistance and self-lubricating properties of the material.

[0008] CN118728854A provides a lightweight self-lubricating wear-resistant spherical bearing and its preparation method. The inner and outer rings of the spherical bearing use titanium alloy as the base material. First, a TiN transition layer, a hard coating, and a soft coating are deposited on the outer spherical substrate of the inner ring in sequence, and then a TiN transition layer and a hard coating are deposited on the inner spherical substrate of the outer ring in sequence. Then, a micro-pit texture is processed on the inner spherical surface of the outer ring by laser thermal effect, and a solid lubricant is filled in the micro-pit texture. This method relies on multi-layer coating technology, which not only increases the complexity and cost of the preparation process, but also makes it difficult to ensure the adhesion of the coating under complex loads and high temperature environments. In addition, the micro-pit texture and solid lubricant may lose their effect at high temperatures, which will further affect the service life of the material, thereby limiting its applicability in certain high-temperature applications.

[0009] In view of the problems existing in existing research, this field urgently needs a method for improving the wear resistance and friction reduction performance of the surface of titanium alloy spherical bearings. Summary of the invention

[0010] In view of the shortcomings of the prior art, the present invention aims to provide a method for improving the self-lubricating performance of titanium alloy spherical bearings. The method can not only optimize the surface structure of spherical bearings and improve their mechanical properties, but also reduce the friction coefficient, thereby achieving efficient and stable tribological performance.

[0011] To achieve this object, the present invention adopts the following technical solutions:

[0012] In a first aspect, the present invention provides a method for improving the self-lubricating property of a titanium alloy material, the method comprising: preparing a nano-lubricating layer on the surface of a titanium alloy substrate modified by ion implantation and thermal oxidation;

[0013] Wherein, the nano-lubricating layer is prepared by ion beam assisted deposition (IBAD).

[0014] The purpose of the present invention is to prepare a titanium alloy material with good self-lubricating property, and to accelerate the ionized Zr metal element to sufficient kinetic energy by using a high-voltage electric field and inject it into a certain depth range on the surface of the titanium alloy joint bearing substrate, introduce zirconium elements to change the surface and subsurface composition of the titanium alloy, and improve the wear resistance of the obtained material itself, so as to achieve the technical effect of "wear resistance". The controllable ion injection energy is used to adjust the diffusion depth and concentration gradient of the zirconium element on the surface of the titanium alloy, form a gradient-distributed zirconium-doped layer, and gradually transition to the substrate, thereby improving the interface bonding force, reducing the interface stress concentration, and avoiding interface peeling. After high-temperature thermal oxidation treatment, the oxygen elements in the atmosphere undergo a process of contact collision, adsorption, decomposition, diffusion, maturation, and growth under high temperature conditions, and a zirconium-based oxide ceramic layer is generated in situ on the surface of the substrate. There is an oxygen-rich diffusion layer between the ceramic layer and the substrate, and there is no risk of peeling. The surface zirconium oxide ceramic layer is dense and stable, which greatly improves the surface hardness and friction and wear performance of the substrate. The surface of the zirconium oxide ceramic layer is deposited with a multi-layer nano-lubricating layer by ion beam assisted deposition technology, and the surface self-lubricating property is improved, achieving the technical effect of "friction reduction". Chemical bonds or ionic bonds are formed through the interface reaction between ions and oxides, which improves the adhesion of the ion membrane and prevents the lubricating layer from peeling off under high-load friction environments.

[0015] Preferably, the nano-lubricating layer is a nano-lubricating silver layer.

[0016] A multi-layer nano-lubricating silver layer is deposited on the surface of the zirconium oxide ceramic layer by ion beam assisted deposition technology. Chemical bonds or ionic bonds are formed through the interface reaction between silver and oxide, which improves the adhesion of the silver film and prevents the lubricating silver film from peeling off under high-load friction environment.

[0017] As a preferred technical solution of the present invention, the steps of preparing the nano-lubricating layer are as follows: the titanium alloy substrate is modified by ion implantation and thermal oxidation to form an oxide ceramic layer, ion cleaning is performed under vacuum conditions, and then ion bombardment and sputtering deposition are performed alternately to form the nano-lubricating layer.

[0018] By alternately using a high-energy ion source and a sputtering source to deposit a lubricating silver film, the problem of the silver film peeling off easily under high-load friction environments is solved, and the service life of the lubricating layer is extended.

[0019] As a preferred technical solution of the present invention, in the sputtering deposition operation, the sputtering voltage is 300-500V (for example, it can be 300V, 350V, 380V, 400V, 420V, 450V, 480V or 500V, etc.), the sputtering current is 0.8-1A (for example, it can be 0.8A, 0.85A, 0.9A, 0.95A or 1A, etc.), and the sputtering gas pressure is 0.2×10 -1 ~1.0×10 -1Pa, for example, can be 0.02Pa, 0.03Pa, 0.05Pa, 0.06Pa, 0.08Pa, 0.09Pa or 0.1Pa, etc., and the time is 1 to 2min (for example, can be 1min, 1.2min, 1.5min, 1.8min or 2min, etc.).

[0020] Preferably, in the ion bombardment operation, the ion source voltage is 30-50 kV (for example, 30 kV, 35 kV, 40 kV, 45 kV or 50 kV, etc.), the ion source current is 10-15 mA (for example, 10 mA, 11 mA, 12 mA, 13 mA, 14 mA or 15 mA, etc.), and the ion source pressure is 1.0×10 -2 ~3.5×10 -2 Pa (for example, it can be 1.0×10 -2 Pa, 1.2×10 -2 Pa, 1.5×10 -2 Pa, 2×10 -2 Pa, 2.5×10 -2 Pa, 3×10 -2 Pa or 3.5×10 -2 Pa, etc.), time 3 to 5 minutes (for example, it can be 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes or 5 minutes, etc.).

[0021] Preferably, the ion bombardment and sputtering deposition are performed alternately and repeated 10 to 20 times, for example, 10 times, 12 times, 13 times, 15 times, 16 times, 17 times, 18 times, 19 times or 20 times.

[0022] As a preferred technical solution of the present invention, in the ion cleaning step, a low-energy ion source is used for ion cleaning, the low-energy voltage is 300-500V (for example, it can be 300V, 350V, 380V, 400V, 420V, 450V, 480V or 500V, etc.), the beam current is 100-150mA (for example, it can be 100mA, 110mA, 120mA, 130mA, 140mA or 150mA, etc.), and the cleaning time is 30-60min (for example, it can be 30min, 35min, 40min, 45min, 50min, 55min or 60min, etc.).

[0023] Preferably, in the ion cleaning step, the vacuum degree is 1.0×10 -2 Pa~3.5×10 -2 Pa, for example, can be 1.0×10 -2 Pa, 1.2×10 -2 Pa, 1.5×10 -2 Pa, 2×10 -2Pa, 2.5×10 -2 Pa, 3×10 -2 Pa, 3.5×10 -2 Pa et al.

[0024] As a preferred technical solution of the present invention, the titanium alloy substrate modified by ion implantation and thermal oxidation is prepared by the following method:

[0025] (1) Surface pretreatment: grinding and polishing the titanium alloy substrate, followed by cleaning and drying;

[0026] (2) zirconium ion implantation: using metal zirconium as an ion implantation source, ion implantation is performed on the sample that has undergone surface pretreatment in step (1) under vacuum conditions;

[0027] In this step, the Zr element has the same lattice type as titanium, belongs to the same main group as Ti on the periodic table, has the same extranuclear electronic structure, and has a similar atomic radius. Zr, as a neutral element, can be infinitely solid-dissolved with a-Ti and B-Ti, so it is appropriate to select Zr as the surface injection element of the titanium alloy. The zirconium ion is accelerated by a high-voltage electric field to be implanted into the surface and subsurface of the titanium alloy to form a zirconium gradient distribution layer. This gradient distribution not only improves the interface bonding force, but also effectively alleviates the interface stress concentration and prevents interface peeling. The controllable ion energy can be used to adjust the diffusion depth and concentration gradient to achieve element distribution optimization, thereby enhancing the bonding stability between the substrate and the functional coating.

[0028] (3) Thermal oxidation: placing the sample after zirconium ion implantation in step (2) in an oxygen atmosphere, heating and keeping the temperature to form a zirconium oxide ceramic layer, and then washing and drying to obtain a titanium alloy substrate modified by ion implantation and thermal oxidation;

[0029] In this step, thermal oxidation treatment is carried out in an oxidizing atmosphere to directly generate a zirconium-based oxide ceramic layer in situ on the substrate surface and form an oxygen-rich diffusion layer to ensure that the coating is dense and stable, and to improve hardness and wear resistance. Combining ion implantation with high-temperature thermal oxidation processes ensures that the oxide layer is metallurgically bonded to the substrate, completely eliminating the risk of oxide layer peeling and optimizing the performance of the wear-resistant ceramic layer.

[0030] As a preferred technical solution of the present invention, after the grinding and polishing treatment in step (1), the surface roughness of the obtained titanium alloy sample is ≤0.1μm, for example, it can be 0.1μm, 0.09μm, 0.08μm, 0.07μm, 0.06μm, 0.05μm, 0.04μm, 0.03μm, 0.02μm or 0.01μm, etc.

[0031] In the present invention, the lower the surface roughness of the titanium alloy material, the more obvious the effect of ion implantation and oxidation process on the performance improvement of the titanium alloy substrate. Taking into account the polishing difficulty and polishing cost of the titanium alloy material, the present invention sets the lower limit of the roughness of the titanium alloy material used to 0.05 μm, preferably 0.1 μm to 0.05 μm.

[0032] Preferably, the cleaning in step (1) is ultrasonic cleaning, and the ultrasonic cleaning is performed using any one of acetone, deionized water or anhydrous ethanol, or two or more of the reagents.

[0033] Preferably, the drying method in step (1) is air drying.

[0034] As a preferred technical solution of the present invention, the parameters of the zirconium ion implantation in step (2) are set as follows: an extraction voltage of 30 to 80 kV, for example, 30 kV, 35 kV, 40 kV, 45 kV, 50 kV, 55 kV, 60 kV, 65 kV, 70 kV, 75 kV or 80 kV, etc.; a trigger frequency of 0.1 to 15 Hz, for example, 0.1 Hz, 1 Hz, 2 Hz, 3 Hz, 5 Hz, 6 Hz, 8 Hz, 10 Hz, 12 Hz, 14 Hz or 15 Hz.

[0035] Preferably, the cathode current is controlled to be 3-10 mA (for example, 3 mA, 4 mA, 5 mA, 6 mA, 7 mA, 8 mA, 9 mA, 10 mA, etc.), the target current is controlled to be 3-10 mA (for example, 3 mA, 4 mA, 5 mA, 6 mA, 7 mA, 8 mA, 9 mA, 10 mA, etc.), and the injection dose is 0.5×10 17 ion·cm -2 ~3×10 17 ion·cm -2 (For example, it can be 0.5×10 17 ion·cm -2 , 1×10 17 ion·cm -2 , 1.5×10 17 ion·cm -2 , 2×10 17 ion·cm -2 , 2.5×10 17 ion·cm -2 or 3×10 17 ion·cm -2 wait).

[0036] Preferably, during the entire ion implantation process, the temperature of the substrate is controlled not to exceed 100° C., for example, it may be 100° C., 95° C., 90° C., 85° C., 80° C. or 70° C., etc.

[0037] Preferably, the ion implantation is performed under vacuum conditions with a vacuum degree of ≥1.0×10 -3 Pa; for example, it can be 1.0×10 -3 , 8×10 -4 ,7×10 -4 , 6×10 -4 or 5.0×10 -4 wait.

[0038] As a preferred technical solution of the present invention, during the thermal oxidation process in step (3), the temperature is raised to 550-650°C (for example, it may be 550°C, 560°C, 570°C, 580°C, 590°C, 600°C, 610°C, 620°C, 630°C, 640°C, 650°C, etc.), the heating rate is 3-5°C / min (for example, it may be 3°C / min, 3.5°C / min, 4°C / min, 4.5°C / min, 5°C / min, etc.), and the insulation time is 3-8h (for example, it may be 3h, 4h, 5h, 6h, 7h, 8h, etc.).

[0039] In a second aspect, the present invention provides a titanium alloy material prepared by the method described in the first aspect.

[0040] In a third aspect, the present invention provides use of the method described in the first aspect or the titanium alloy material described in the second aspect in preparing a titanium alloy spherical bearing.

[0041] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] (1) The present invention combines a zirconium ion implantation layer, a zirconium oxide ceramic layer and a nano-lubricating film to form a gradient transition, stable and dense multi-layer structure, which has both low friction and high wear resistance. Through the composite multi-layer structure design, the synergistic optimization of surface hardness and lubrication performance is achieved (the outer layer provides an extremely low friction coefficient, and the inner layer has high hardness and high toughness support), so that the material has excellent self-lubrication and exhibits excellent friction reduction and wear resistance under heavy load and high friction conditions.

[0044] (2) The method of the present invention can be used on the surfaces of various materials including but not limited to titanium alloy spherical bearings, and can increase the friction coefficient of the material by 33% to 88%, reduce the wear scar width by 11% to 17%, and reduce the wear scar depth by 20% to 50%. Therefore, this technology can not only significantly improve its durability under high friction conditions, but also effectively broaden the application field of titanium alloy spherical bearings. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic diagram of the structure of a titanium alloy spherical plain bearing; 1 is a spherical plain bearing, 2 is a rod end, 101 is an outer ring of the spherical plain bearing, 102 is an inner ring of the spherical plain bearing, 201 is a rod end housing, 202 is a grease hole, and 203 is a rod end handle.

[0046] Figure 2 Schematic diagram of the surface of the titanium alloy substrate after surface modification; wherein 301 is a nano multilayer lubricating layer, 302 is an oxide ceramic layer, 303 is an ion implantation influence zone, 304 is an element implantation layer, and 305 is a titanium alloy substrate.

[0047] Figure 3 The figures are the reaction wear width and wear depth detection diagrams of each sample material; wherein Figure I is the sample obtained in Example 1, Figure II is the sample obtained in Example 2, Figure III is the sample obtained in Example 3, and Figure IV is the sample obtained in Comparative Example 1.

[0048] Figure 4 It is a friction coefficient curve diagram of each sample material in the rotational friction experiment; wherein Figure I is the sample obtained in Example 1, Figure II is the sample obtained in Example 2, Figure III is the sample obtained in Example 3, and Figure IV is the sample obtained in Comparative Example 1. DETAILED DESCRIPTION

[0049] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0050] In the following examples, unless otherwise specified, all reagents and consumables used were purchased from conventional reagent manufacturers in the field; unless otherwise specified, all experimental methods and technical means used were conventional methods and means in the field.

[0051] The method of the present invention can improve the self-lubricating property of titanium alloy materials and achieve the effect of reducing friction and resisting wear. The method can be applied to the surfaces of various materials including but not limited to titanium alloy spherical bearings. In the specific implementation part, the titanium alloy spherical bearings used can be as follows: Figure 1 The bearing of the structure shown in the figure comprises a spherical bearing 1 and a rod end 2; the spherical bearing comprises a spherical bearing outer ring 101 and a spherical bearing inner ring 102, and the rod end 2 comprises a rod end housing 201, a grease hole 202, and a rod end handle 203; the part improved by the method described in the present invention is the working surface of the spherical bearing, that is, the outer ring and the inner ring of the spherical bearing.

[0052] The surface structure of the titanium alloy spherical bearing prepared by the method of the present invention is as follows: Figure 2As shown, from the outside to the inside are the nano multi-layer lubricating layer 301 , the element injection layer 304 (which can be divided into an oxide ceramic layer 302 and an ion injection influence zone 303 ) and the titanium alloy substrate 305 .

[0053] Example 1

[0054] This embodiment provides a method for improving the self-lubricating performance of a titanium alloy spherical plain bearing, and the specific steps are as follows:

[0055] 1. Surface pretreatment (polishing and cleaning)

[0056] The titanium alloy sample is a titanium alloy spherical bearing, and the material selected is Ti-6Al-4V (grade TC4) as the matrix.

[0057] The titanium alloy specimens were polished with 150#, 600#, 1000#, 2000#, 3000#, and 5000# SiC sandpaper in sequence until there were no obvious scratches on the surface of the specimens, and then polished with polishing paste to ensure that the roughness (Ra) was 0.1μm;

[0058] The polished titanium alloy specimens were immersed in acetone, deionized water and anhydrous ethanol for ultrasonic cleaning for 10 min respectively, and the surface was air-dried.

[0059] 2. Ion implantation

[0060] The cleaned titanium alloy sample was clamped on the water-cooled base of the ion implanter and evacuated to 1×10 -3 After Pa, the ion source is turned on for ion implantation;

[0061] The ion source cathode is Zr, the extraction voltage is 30 kV, the trigger frequency is 0.01-15 Hz, the cathode current is controlled to be 3 mA, the target current is controlled to be 3 mA, and the injection dose is 0.5×10 17 ion·cm -2 During the entire ion implantation process, the temperature of the substrate is controlled not to exceed 100°C.

[0062] After the implantation process is completed, wait for the temperature in the process chamber to drop to room temperature, fill it with air, take out the sample, and complete the zirconium ion implantation process.

[0063] 3. Thermal oxidation to form a ceramic layer

[0064] The ion-implanted titanium alloy sample was placed horizontally in a high-temperature tube furnace and heated to 550°C at a heating rate of 3°C / min. The holding time was 6 hours and the furnace was cooled to complete the thermal oxidation in-situ preparation of the zirconia ceramic layer.

[0065] 4. Deposition of lubricating layer

[0066] After the oxidized titanium alloy sample was cleaned again, it was clamped in the furnace chamber of the ion beam assisted deposition coating equipment. The vacuum was evacuated to less than 3.5×10 -2 At Pa, the low-energy ion source was turned on for ion cleaning, with a low-energy voltage of 300 V, a beam current of 100 mA, and a cleaning time of 60 min;

[0067] The low energy ion source was turned off and the sputtering source was turned on to start the deposition of the Ag coating.

[0068] During the coating deposition process, the high energy ion source and the sputtering source are turned on alternately.

[0069] Sputtering source parameters: sputtering voltage 300 V, sputtering current 1 A, sputtering gas pressure 0.1 Pa, time 1 min; high energy ion source parameters: ion source voltage 30 kV, ion source current 10 mA, ion source gas pressure 1.0 × 10 -2 Pa, time 3min; repeat the steps 10 times.

[0070] After the coating is completed, the furnace is cooled and then taken out of the furnace to complete the preparation.

[0071] Example 2

[0072] This embodiment provides a method for improving the self-lubricating performance of a titanium alloy spherical bearing. The operation steps are consistent with those of Embodiment 1, and the parameters of each step are shown in Table 1.

[0073] Example 3

[0074] This embodiment provides a method for improving the self-lubricating performance of a titanium alloy spherical bearing. The operation steps are consistent with those of Embodiment 1, and the parameters of each step are shown in Table 1.

[0075] Table 1 Example data

[0076]

[0077]

[0078]

[0079] Comparative Example 1

[0080] A titanium alloy spherical bearing prepared from an unprocessed titanium alloy sample Ti-6Al-4V (grade TC4) is referred to as Comparative Example 1.

[0081] Comparative Example 2

[0082] This comparative example provides a method for improving the self-lubricating performance of a titanium alloy spherical bearing, wherein in the pretreatment step, the surface roughness is adjusted to 0.6 μm, and the remaining steps are consistent with those of Example 1.

[0083] Comparative Example 3

[0084] This comparative example provides a method for improving the self-lubricating performance of a titanium alloy spherical bearing, wherein in the pretreatment step, the surface roughness is adjusted to 0.01 μm, and the remaining steps are consistent with those of Example 1.

[0085] Comparative Example 4

[0086] In this comparative example, after the ceramic layer is formed by thermal oxidation, the nano-lubricating layer is not prepared, and the remaining steps are consistent with those in Example 1.

[0087] Comparative Example 5

[0088] In this comparative example, tungsten disulfide (WS2) is selected as the lubricating layer. In the step of depositing the lubricating layer, Ag is replaced with WS2 to prepare the tungsten disulfide lubricating layer, and the remaining steps are consistent with Example 1.

[0089] Performance Testing

[0090] 1. Microhardness

[0091] According to GB / T 4340.1-2009 "Metallic Materials Vickers Hardness Test Part 1: Test Method", at the 100gf force level, the loading and holding time was set to 10s, and 5 points were measured for each sample. The test data are shown in Table 2.

[0092] Table 2 Vickers hardness test results

[0093]

[0094]

[0095] 2. Friction and wear performance

[0096] The friction and wear test parameters were set as load 200g; friction pair Si3N4 ball; friction radius 4mm; speed 200r / min; time 20min.

[0097] The reaction wear width and wear depth detection diagrams of Examples 1 to 3 and Comparative Example 1 are as follows Figure 3 As shown, Figure I is the sample obtained in Example 1, Figure II is the sample obtained in Example 2, Figure III is the sample obtained in Example 3, and Figure IV is the sample obtained in Comparative Example 1.

[0098] The friction and wear properties of Examples 1 to 3 and Comparative Example 1 are as follows: Figure 4 As shown; Figure I is the sample obtained in Example 1, Figure II is the sample obtained in Example 2, Figure III is the sample obtained in Example 3, and Figure IV is the sample obtained in Comparative Example 1.

[0099] The specific test data obtained are shown in Table 3.

[0100] Table 3 Friction and wear test results

[0101]

[0102]

[0103] Combining the data in Table 2 and Table 3, it can be seen that by comparing the embodiment with the comparative example 1, the titanium alloy material prepared by the preparation method of the present invention has a Vickers hardness increased by 22% to 35%, a friction coefficient increased by 33% to 88%, a wear scar width reduced by 11% to 17%, and a wear scar depth reduced by 20% to 50%.

[0104] Comparing Example 1 with Comparative Examples 2 to 4, it can be seen that Comparative Examples 2 and 3 adjust the surface roughness in the pretreatment step, and their Vickers hardness test results also show a significant improvement, but the friction coefficient and wear resistance in Comparative Example 2 are significantly reduced compared with Example 1; Comparative Example 3 has a certain increase compared with Example 1, but the surface roughness is adjusted to 0.01μm, which has great polishing difficulty and high polishing cost. Taking all factors into consideration, the present invention sets the lower limit of the roughness of the titanium alloy material used to 0.05μm, preferably 0.1μm to 0.05μm.

[0105] Comparison between the embodiment and comparative example 5 shows that although WS2 also has self-lubricating function, its hardness is relatively high and it is easy to peel off due to loose bonding with the substrate. The peeling material will be mixed in the working surface, aggravating wear. On the contrary, after the Ag coating peels off, it will become a filler in the defects of the working surface, which will increase the lubrication performance. In addition, Ag can maintain good stability in high temperature environment (over 300°C), while WS2 will decompose.

[0106] In addition, when implementing the preparation method, attempts were made to adjust parameters such as sputtering time, sputtering voltage, and ion source current.

[0107] However, extending the sputtering time will increase the thickness of the coating, thereby improving the mechanical strength and wear resistance of the coating. However, too thick a coating may lead to internal stress accumulation, and the coating may peel off during the preparation process. Shortening the sputtering time will reduce the coating thickness, resulting in a deterioration in the protective effect of the coating (such as corrosion resistance and wear resistance). In addition, there may be discontinuities on the coating surface, resulting in a decrease in lubricity. Increasing the sputtering voltage will increase the sputtering rate on the target surface, thereby accelerating the deposition rate of the coating. At the same time, the incidence of high-energy particles may cause the coating particles to be denser, and the hardness and wear resistance of the coating will be improved. However, too high a voltage may cause excessive energy input, resulting in increased internal stress in the coating and affecting adhesion. Reducing the sputtering voltage will slow down the deposition rate, and the coating particles may be rougher and less dense, thereby reducing the wear resistance and lubricity of the coating. Increasing the ion source current will increase the ion bombardment intensity, thereby improving the bonding force (adhesion) between the coating and the substrate and the surface smoothness of the coating. Ion bombardment may also promote the densification of the coating and improve the mechanical properties and corrosion resistance of the coating. However, too high an ion current may cause re-sputtering of the coating material or excessive surface ablation, affecting the uniformity of the coating. Reducing the ion source current will reduce the ion bombardment intensity, the bonding strength and density of the coating may decrease, and the surface may become rough and more prone to peeling, thus affecting the wear resistance and corrosion resistance of the coating.

[0108] In summary, the reasonable process parameter optimization of the present invention can achieve an optimal balance between the density, uniformity, bonding strength and performance of the coating.

[0109] The applicant declares that the above is only a specific implementation mode 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 shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for improving the self-lubricating property of titanium alloy material, characterized in that: The method comprises: preparing a nano-lubricating layer on the surface of a titanium alloy substrate modified by ion implantation and thermal oxidation; The nano-lubricating layer is prepared by ion beam assisted deposition.

2. The method according to claim 1, characterized in that The nano-lubricating layer is a nano-lubricating silver layer; The preparation steps of the nano-lubricating layer are as follows: the titanium alloy substrate is subjected to ion implantation and thermal oxidation modification to form an oxide ceramic layer, ion cleaning is performed under vacuum conditions, and then ion bombardment and sputtering deposition are performed alternately to form the nano-lubricating layer.

3. The method according to claim 2, characterized in that In the sputtering deposition operation, the sputtering voltage is 300-500 V, the sputtering current is 0.8-1 A, and the sputtering gas pressure is 0.2×10 -1 ~1.0×10 -1 Pa, time 1 to 2 minutes; During the ion bombardment operation, the ion source voltage is 30-50 kV, the ion source current is 10-15 mA, and the ion source pressure is 1.0×10 -2 ~3.5×10 -2 Pa, time 3 to 5 minutes; The ion bombardment and sputtering deposition are performed alternately and repeated 10 to 20 times.

4. The method according to claim 2, characterized in that: In the ion cleaning step, a low-energy ion source is used for ion cleaning, the low-energy voltage is 300-500V, the beam current is 100-150mA, and the cleaning time is 30-60min.

5. The method according to any one of claims 2 to 4, characterized in that: The titanium alloy substrate modified by ion implantation and thermal oxidation is prepared by the following method: (1) Surface pretreatment: grinding and polishing the titanium alloy substrate, followed by cleaning and drying; (2) zirconium ion implantation: using metal zirconium as an ion implantation source, ion implantation is performed on the sample that has undergone surface pretreatment in step (1) under vacuum conditions; (3) Thermal oxidation: The sample after zirconium ion implantation in step (2) is placed in an oxygen atmosphere, heated and kept warm to form a zirconium oxide ceramic layer, and then cleaned and dried to obtain a titanium alloy substrate modified by ion implantation and thermal oxidation.

6. The method according to claim 5, characterized in that After the grinding and polishing treatment in step (1), the surface roughness of the titanium alloy sample obtained is ≤0.1 μm; The cleaning in step (1) is ultrasonic cleaning, and the ultrasonic cleaning is performed using any one of acetone, deionized water or anhydrous ethanol, or two or more reagents; The drying method in step (1) is air drying.

7. The method according to claim 5, characterized in that The parameters of the zirconium ion implantation in step (2) are set as follows: extraction voltage is 30-80 kV, trigger frequency is 0-15 Hz, cathode current is controlled to be 3-10 mA, target current is controlled to be 3-10 mA, In the zirconium ion implantation of step (2), the implantation dose is 0.5×10 17 ion·cm -2 ~3×10 17 ion·cm -2 ; During the zirconium ion implantation in step (2), the temperature of the base does not exceed 100°C.

8. The method according to claim 5, characterized in that The heating rate of the thermal oxidation in step (3) is 3-5°C / min; The temperature of the thermal oxidation in step (3) is 550-650° C. The thermal oxidation holding time in step (3) is 3 to 8 hours.

9. The titanium alloy material prepared by the method according to any one of claims 1 to 8.

10. Use of the method according to any one of claims 1 to 8 or the titanium alloy material according to claim 9 in the preparation of titanium alloy spherical bearings.

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