Preparation method of diamond-like carbon film based on ion beam energy regulation

Abstract

The application relates to the technical field of diamond-like carbon film preparation methods, and particularly discloses a diamond-like carbon film preparation method based on ion beam energy regulation, which comprises the following steps: S1, substrate pretreatment; S2, preparation of a metal transition layer; the metal transition layer is obtained by physically vapor depositing a main ion beam with an energy of 700-900 eV and bombarding a chromium target or a tungsten target at 80-220 DEG C for 0.5-2 hours on the surface of a substrate; S3, preparation of a surface modification layer; the surface modification layer is obtained by depositing a graphite target as a carbon source and introducing a fluorine-containing or tungsten-containing doping source on the surface of the metal transition layer through the graphite target bombarded by a main ion beam at 100-300 DEG C for 2-4 hours, wherein the main ion beam has an energy of 700-900 eV, a beam current of 63-81 mA and a beam current energy ratio of 0.09; and S4, low-temperature annealing. The diamond-like carbon film prepared by the method has strong adhesion to the substrate, low friction, high wear resistance, good mechanical properties and a long service life under harsh working conditions such as heavy load, impact and reciprocating friction.

Description

Technical Field

[0001] This invention relates to the technical field of diamond-like carbon thin film preparation methods, and specifically discloses a method for preparing diamond-like carbon thin films based on ion beam energy regulation. Background Technology

[0002] Diamond-like carbon (DLC) films are a type of film that combines the properties of sp... 2 (Graphite phase) and sp 3 Amorphous carbon materials with (diamond-phase) hybrid bonds are widely used in aerospace, precision machinery, mold manufacturing, biomedicine, and optical protection due to their extremely high hardness, extremely low coefficient of friction, excellent wear resistance, good chemical inertness, and wide spectral transmittance. However, the practical application of DLC films is often limited by their inherent "performance inversion" relationship: that is, high sp[…]. 3 The high hardness resulting from the high content of the active ingredient and the insufficient film-substrate bonding force, high brittleness, and easy cracking caused by the high residual compressive stress are contradictory.

[0003] Currently, the mainstream physical vapor deposition (PVD) technologies for preparing DLC ​​thin films mainly include magnetron sputtering, arc deposition, and ion beam sputtering deposition (IBD). While magnetron sputtering produces uniform films with few large particles, the low energy of the deposited particles leads to low spp content in the film. 3 The bond content is usually low, making it difficult to meet the hardness and wear resistance requirements of heavy-duty applications; arc plating technology can obtain high sp2 content by utilizing high current density. 3 While high-density DLC films can produce dense films, the resulting large macroscopic particles and high surface roughness significantly increase the contact stress of the friction pair, leading to premature failure and abrasive wear. Ion beam sputtering deposition (IBD), a non-equilibrium deposition technique, uses a high-energy ion beam to bombard a target to generate sputtered particles, enabling the fabrication of dense thin films at relatively low substrate temperatures.

[0004] However, in traditional IBD processes, the ion beam is mainly used to provide sputtering energy, and its primary target is the target material. It lacks effective control over the surface of the growing film, leading to the following problems: 1. The contradiction between stress and hardness; in order to improve density and sp... 3 1. To increase the content, the ion beam energy needs to be increased, but this will introduce huge residual compressive stress. When the stress exceeds the limit of the film-substrate bonding force, the film will peel off or crack; 2. When it involves a complex multilayer structure, the interfacial bonding force between the layers is weak, and the service life is short under harsh working conditions such as heavy load, impact and reciprocating friction.

[0005] To address the aforementioned issues, existing technologies employ multi-ion beam sputtering and low-energy ion beam assisted deposition to synthesize multi-element doped DLC coatings. Specifically, a gradient transition layer (metal transition layer) is first prepared on the substrate surface using ion beam assisted deposition. Then, a multi-element doped DLC coating is prepared using multi-ion beam sputtering and low-energy ion beam assisted deposition. During the multi-element doped DLC coating preparation process, carbon and metal particles generated by the sputtering ion source bombarding the graphite and metal targets are deposited onto the workpiece surface. Simultaneously, gas ions generated by the assisted deposition ion source continuously bombard the surface of the growing film, controlling the microstructure of the film and achieving multi-element doping. Although this existing technology can improve the performance of DLC coatings to some extent and achieve complementary advantages of different doping elements, the interfacial bonding between the film and the substrate remains weak. Furthermore, there are abrupt interfacial changes between the gradient transition layer and the substrate, and between the gradient transition layer and the multi-element doped layer. Consequently, the service life of the resulting products under harsh operating conditions remains unsatisfactory. Summary of the Invention

[0006] In view of the background technology, the present invention provides a method for preparing diamond-like carbon thin films based on ion beam energy regulation, which aims to improve the interfacial bonding force of the film substrate and solve the problem of short service life of DLC thin films under harsh working conditions caused by the abrupt change of interlayer interface.

[0007] To achieve the above objectives, the main technical solutions adopted by the present invention are as follows.

[0008] A method for preparing diamond-like carbon thin films based on ion beam energy modulation includes the following steps: S1. Substrate pretreatment, including cleaning treatment for removing contaminant layers from the substrate surface and ion beam cleaning for obtaining atomically clean surfaces; S2. Prepare a metal transition layer by bombarding a chromium target and / or a tungsten target with a main ion beam of 700-900 eV and a temperature of 80-220℃ on the substrate surface using a physical vapor deposition process. S3. Prepare a surface-modified layer by using a graphite target as the carbon source and introducing fluorine- or tungsten-containing dopant sources. Deposit FC nanocrystalline / amorphous carbon composite structure or WC nanocrystalline / amorphous carbon composite structure on the surface of the metal transition layer by bombarding the graphite target with a main ion beam at 100-300℃ for 2-4 hours. This composite structure has both ultra-low friction and high wear resistance. The main ion beam energy is 700-900 eV, the beam current is 63-81 mA, and the beam current-to-energy ratio is 0.09. S4. Low-temperature annealing: Under vacuum or an inert gas / hydrogen mixed atmosphere, perform low-temperature annealing at 200-400℃ for 0.5-3 hours. This low-temperature annealing can further reduce stress by about 20% and simultaneously lock in SP. 3 Key to prevent reverting to sp 2 .

[0009] The operation flow of the above preparation method is as follows: Figure 1 As shown. Compared with the prior art, the present invention achieves a high thermo-mechanical matching degree between the metal transition layer and the substrate, and between the surface properties and the metal transition layer by precisely controlling the key technical parameters of the metal transition layer and the surface modification layer. Combined with low-temperature annealing process to repair defects and release stress, a high-quality DLC film is obtained. It has strong interfacial adhesion to the substrate and has a surface modification layer with excellent mechanical properties and friction resistance, which significantly extends the service life of the DLC film under harsh conditions such as heavy load, impact and reciprocating friction.

[0010] Furthermore, a gradient functional layer is first deposited on the metal transition layer, and then a surface modification layer is prepared. The preparation operation of the gradient functional layer is as follows: carbon particles are sputtered onto the surface of the metal transition layer by bombarding the graphite target with a main ion beam to form a carbon film, while the surface of the growing carbon film is continuously bombarded with an auxiliary ion beam. The main ion beam and the auxiliary ion beam are controlled independently. The energy of the main ion beam is 700-900 eV, the energy of the auxiliary ion beam is 70-135 eV, and the energy ratio of the main ion beam to the auxiliary ion beam is 1:(0.10-0.15). Preferably, the energy of the main ion beam is 800 eV and the energy of the auxiliary ion beam is 88 eV, with the energy ratio of the main ion beam to the auxiliary ion beam being 1:0.11.

[0011] In this technical solution, by controlling the energy of the main ion beam, the energy of the auxiliary ion beam, and the ratio of the energy of the main ion beam to the energy of the auxiliary ion beam, the sp in the gradient functional layer can be precisely adjusted. 3 with sp 2 By controlling the bonding content range and residual stress distribution, a gradient functional layer with "high density" and "low damage" is obtained. While ensuring the high mechanical properties of the bulk, the film-substrate bonding force is further improved. Moreover, it plays a bridging role between the metal transition layer and the surface modification layer (F or W doped layer) and can effectively solve the problem of interface abrupt change.

[0012] In this technical solution, the energy of the main ion beam can specifically be 700 eV, 710 eV, 720 eV, 730 eV, 740 eV, 750 eV, 760 eV, 770 eV, 780 eV, 790 eV, 800 eV, 810 eV, 820 eV, 830 eV, 840 eV, 850 eV, 860 eV, 870 eV, 880 eV, 890 eV, 900 eV, etc., and the energy of the auxiliary ion beam can specifically be 70 eV, 71 eV, etc. The energies range from 72eV, 73eV, 74eV, 75eV, 76eV, 77eV, 78eV, 79eV, 80eV, 85eV, 90eV, 95eV, 100eV, 105eV, 110eV, 115eV, 120eV, 125eV, 130eV, to 135eV, etc. The energy ratio of the main ion beam to the auxiliary ion beam can be 1:0.10, 1:0.11, 1:0.12, 1:0.13, 1:0.14, 1:0.15, etc.

[0013] Furthermore, the specific preparation method of the gradient functional layer can be selected from either of the following two methods: Method 1 divides the gradient functional layer into three layers—bottom, middle, and top—based on their distance from the metal transition layer. When preparing the bottom layer, the main ion beam energy is 700 eV to ensure interfacial bonding; when preparing the middle layer, the main ion beam energy is 800 eV to balance hardness and stress; and when preparing the top layer, the main ion beam energy is 900 eV to improve surface hardness and wear resistance. Method 1's fabrication process results in higher quality gradient functional layers and is more conducive to bonding between the metal transition layer and the doped layer. Method 2 involves linearly increasing the main ion beam energy from 700 eV to 900 eV and then linearly decreasing it back to 700 eV during the fabrication of the entire gradient functional layer, creating a cycle of energy modulation. This operation in Method 2 enables the sp... 3 The bond content forms a smooth transition, further eliminating the problem of abrupt interface changes.

[0014] Furthermore, when fabricating the gradient functional layers, the main ion beam emission source uses a Kaufman type or radio frequency (RF) ion source with a flux density of 2-5 mA / cm². 2 The auxiliary ion beam emission source adopts an End-Hall type ion source that points directly to the substrate surface, and its ion incident angle is at an angle of 0-60° with the substrate normal.

[0015] Furthermore, in step S3, the preparation of the WC nanocrystalline / amorphous carbon composite structure involves the following steps: the doping source is a high-purity tungsten wafer, which is fixed to the surface of a graphite target. The amount of tungsten doping is controlled by adjusting the coverage area of ​​the high-purity tungsten wafer on the graphite target. For example, the doping source can be 2-4 high-purity tungsten wafers with a diameter of 10-20 mm and a thickness of 1 mm. The preferred fixing method is adhesive bonding, such as using silver paste to bond the high-purity tungsten wafer to the surface of the graphite target.

[0016] Furthermore, in step S3, the tungsten content in the WC nanocrystalline / amorphous carbon composite structure is 3-10 at%, specifically 3 at%, 3.1 at%, 3.2 at%, 3.3 at%, 3.4 at%, 3.5 at%, 3.6 at%, 3.7 at%, 3.8 at%, 3.9 at%, 4 at%, 4.5 at%, 5 at%, 5.5 at%, 6 at%, 6.5 at%, 7 at%, 7.5 at%, 8 at%, 8.5 at%, 9 at%, 9.5 at%, 10 at%, etc. Preferably, in step S3, the main ion beam energy is 800 eV, the beam current is 72 mA, and the tungsten content in the WC nanocrystalline / amorphous carbon composite structure is 6.2 at.

[0017] In this technical solution, the increase in W doping leads to a continuous increase in the WC nanocrystalline / amorphous carbon composite structure, while the three-dimensional cross-linked structure of the amorphous carbon network is gradually weakened. 3 With the proportion of W continuously decreasing, appropriate doping is key to achieving a synergistic improvement in both the load-bearing capacity and frictional service performance of the substrate. For example, a W doping amount below 3 at% will lead to insufficient hardness, while an amount above 10 at% will cause brittleness, resulting in a sharp drop in wear resistance. Considering the comprehensive performance of the surface modification layer, a W doping amount of 3-10 at% is preferable. In particular, a doping amount of 6.2 at% achieves the best balance between carbon network integrity, internal stress relief, and dispersion strengthening, resulting in a surface modification layer with optimal hardness, friction reduction, and wear resistance.

[0018] In this technical solution, increasing the fluorine (F) doping amount simultaneously enhances the film's hardness, Young's modulus, and hydrophobicity. However, excessive F weakens the continuity of the carbon network and reduces hardness and wear resistance. Considering all factors, the F doping amount should be controlled between 5-10 at%, which helps the surface-modified layer achieve a balance between mechanical and tribological properties. In particular, the FC nanocrystalline / amorphous carbon composite structure with a fluorine content of 7.92 at% formed when the main ion beam energy is 800 eV and the beam current is 72 mA exhibits the lowest coefficient of friction.

[0019] Furthermore, in step S3, the preparation operation of the FC nanocrystalline / amorphous carbon composite structure is as follows: the doping source is a high-purity MgF2 sheet or a high-purity PTFE sheet, the high-purity MgF2 sheet or high-purity PTFE sheet is fixed on the surface of the graphite target, and the doping amount of fluorine is controlled by adjusting the coverage area of ​​the high-purity MgF2 sheet or high-purity PTFE sheet on the graphite target.

[0020] Furthermore, in step S3, the fluorine content in the FC nanocrystalline / amorphous carbon composite structure is 5-10 at%, specifically 5 at%, 5.1 at%, 5.2 at%, 5.3 at%, 5.4 at%, 5.5 at%, 5.6 at%, 5.7 at%, 5.8 at%, 5.9 at%, 6 at%, 6.5 at%, 7 at%, 7.5 at%, 8 at%, 8.5 at%, 9 at%, 9.5 at%, 10 at%, etc.; when the fluorine content is controlled within the above range, an FC nanocrystalline / amorphous carbon composite structure with lubricating function can be formed, thereby reducing friction. Preferably, in step S3, the main ion beam energy is 800 eV, the beam current is 72 mA, and the fluorine content in the FC nanocrystalline / amorphous carbon composite structure is 7.92 at.

[0021] In this technical solution, increasing the fluorine (F) doping amount simultaneously enhances the film's hardness, Young's modulus, and hydrophobicity. However, excessive F weakens the continuity of the carbon network and reduces hardness and wear resistance. Considering all factors, the F doping amount should be controlled between 5-10 at%, which helps the surface-modified layer achieve a balance between mechanical and tribological properties. In particular, the FC nanocrystalline / amorphous carbon composite structure with a fluorine content of 7.92 at% formed when the main ion beam energy is 800 eV and the beam current is 72 mA exhibits the lowest coefficient of friction.

[0022] Furthermore, in step S2, the metal transition layer comprises a high-purity chromium layer with a thickness of 50-200 nm and a chromium-tungsten alloy layer with a thickness of 100-300 nm. The chromium-tungsten alloy layer is a single-layer chromium-tungsten alloy layer or a multilayer film structure with alternating tungsten nanofilm layers and chromium nanofilm layers. In the preparation process shown in steps S2 and S3, a bias voltage of -50V to -200V is applied to the substrate and pulse modulation is performed at a frequency of 10-100kHz, with a pulse duty cycle of 20%-80%. During the deposition of the high-purity chromium layer, a main ion beam with an energy of 800 eV is used to bombard the chromium target, and an auxiliary ion beam with an energy of 100 eV is used to simultaneously bombard the surface of the high-purity chromium layer during deposition. During the deposition of a single-layer chromium-tungsten alloy layer, a main ion beam with an energy of 800 eV is used to bombard the chromium-tungsten alloy target, and an auxiliary ion beam with an energy of 100 eV is used to simultaneously bombard the surface of the deposited chromium-tungsten alloy layer. In the deposition of the multilayer film structure, a main ion beam with an energy of 800eV is used to alternately bombard a tungsten target and a chromium target to form a multilayer film structure in which tungsten nanofilms and chromium nanofilms are arranged alternately. One tungsten nanofilm and one chromium nanofilm constitute one repeating unit. The multilayer film structure preferably has 5-10 repeating units.

[0023] In this technical solution, the metal transition layer is designed as a two-layer structure consisting of a 50-200 nm thick high-purity chromium layer and a 100-300 nm thick chromium-tungsten alloy layer. The high-purity chromium deposition scheme shown helps to obtain a highly dense high-purity chromium layer. The deposition scheme using a single-layer chromium-tungsten alloy layer or a multilayer film structure with alternating tungsten and chromium nanofilm layers can obtain a chromium-tungsten alloy layer that resists cracking and buffers the coefficient of thermal expansion. The synergistic effect of the high-purity chromium layer and the chromium-tungsten alloy layer significantly reduces residual compressive stress, enhances the bonding force with the substrate interface, and prevents the propagation of interface layer cracks, thus preventing film peeling or cracking and further extending the service life of the diamond-like carbon film under harsh conditions such as heavy loads, impacts, and reciprocating friction. In particular, the multilayer film structure with alternating tungsten and chromium nanofilm layers can also improve interface toughness, resulting in a more significant improvement in service life.

[0024] In this technical solution, a "pulse bias" technique is introduced in both steps S2 and S3 during the deposition process. A negative bias is applied to the substrate and pulse modulation is performed simultaneously with deposition. The specific bias voltage can be -50V, -51V, -52V, -53V, -54V, -55V, -56V, -57V, -58V, -59V, -60V, -65V, -70V, -80V, -90V, -100V, -110V, -120V, -130V, -140V, -150V, -160V, -170V, -180V, -190V, or -200V, etc., and the pulse modulation frequency can be... The pulse frequencies range from 10kHz, 11kHz, 12kHz, 13kHz, 14kHz, 15kHz, 16kHz, 17kHz, 18kHz, 19kHz, 20kHz, 25kHz, 30kHz, 40kHz, 50kHz, 60kHz, 70kHz, 80kHz, 90kHz, to 100kHz, with specific duty cycles of 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, to 80%. A negative bias within this range attracts more ions to bombard the substrate, enhancing the film's density and promoting sp... 3 Bond formation; high-frequency pulse modulation within the aforementioned range reduces ion accumulation, resulting in an ultrathin and sp... 3The content is close to that of diamond; the aforementioned pulse duty cycle allows surface-adsorbed atoms to undergo sufficient thermal relaxation and surface diffusion, thereby maintaining a high sp content. 3 While reducing the content, it effectively suppresses the generation of macroscopic particles and the formation of microcracks; the three factors interact and work synergistically, combined with the low-temperature annealing shown in step S4, resulting in a diamond-like carbon film that possesses both good hardness and toughness and strong interfacial adhesion. In particular, the typical parameter combination of -100V bias, 40% pulse duty cycle, 20kHz frequency, 250℃, and annealing for 45min is particularly effective in suppressing microcracks and macroscopic particles, resulting in the best overall performance of the diamond-like carbon film.

[0025] Furthermore, in step S1, the specific operation of ion beam cleaning is as follows: a mixed gas of Ar and H2 with a volume ratio of 1:(1-4) is introduced into the vacuum environment, and a high-density plasma is generated by excitation using a radio frequency power supply. The substrate is bombarded with plasma for 30-60 minutes. While the plasma bombardment further removes physically adsorbed contaminants (such as surface oxide layer and adsorbed impurities), it can also introduce active hydrogen atoms on the substrate surface, providing more dangling bond sites for the subsequent nucleation of carbon films.

[0026] As for the cleaning process, it is a conventional technique in the field, which includes sequential ultrasonic cleaning with organic solvents, rinsing with deionized water, and drying. The cleaning process is mainly used to improve the cleanliness of the substrate surface, thereby improving the bonding performance between the film and the substrate, and improving the repeatability and reliability of the experimental results.

[0027] Compared with the prior art, the present invention has at least the following beneficial effects: (1) By precisely controlling the key technical parameters of the metal transition layer and the surface modification layer, a high thermo-mechanical matching degree between the metal transition layer and the substrate, and between the surface modification layer and the metal transition layer is achieved. Combined with the low temperature annealing process to repair defects and release stress, the resulting DLC ​​film has strong interfacial bonding with the substrate and has low friction, high wear resistance and excellent mechanical properties. It has a long service life under harsh working conditions such as heavy load, impact and reciprocating friction.

[0028] (2) Based on the above, by adding a gradient functional layer, a multi-layer structure of “metal transition layer-gradient functional layer-surface modification layer” is constructed. While ensuring the high mechanical properties of the substrate, the film-substrate bonding force is further improved. It plays a bridging role between the metal transition layer and the surface modification layer. The synergistic effect of the multi-layer structure also helps to solve the problem of interface abrupt change.

[0029] (3) In addition, the specific design of the metal transition layer has been optimized. The synergistic effect of the high-purity chromium layer and the chromium-tungsten alloy layer can significantly reduce the residual compressive stress, enhance the bonding force with the substrate interface, and prevent the expansion of interface layer cracks, prevent the film layer from peeling or cracking, and further extend its service life under harsh working conditions. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the preparation process of the diamond-like carbon thin film preparation method based on ion beam energy control in this invention.

[0032] Figure 2 The surface SEM images of W-DLC films obtained in step S3 of this invention at different main ion beam energies are: (a) 700 eV; (b) 800 eV; (c) 900 eV.

[0033] Figure 3 White light interference morphology of W-DLC films obtained at different main ion beam energies in step S3 of the present invention: (a) 700 eV, (b) 800 eV, (c) 900 eV.

[0034] Figure 4 The following are Raman peak fitting diagrams of W-DLC films obtained at different main ion beam energies in step S3 of this invention: (a) 700 eV, (b) 800 eV, (c) 900 eV.

[0035] Figure 5 XPS spectra of W-DLC films obtained at different main ion beam energies in step S3 of the present invention: (a) overall XPS spectrum, (b) C1s peak fitting diagram of 700eV sample, (c) C1s peak fitting diagram of 800eV sample, (d) C1s peak fitting diagram of 900eV sample.

[0036] Figure 6 The following are the W-DLC films obtained in step S3 of this invention with different main ion beam energies: (a) nanoindentation loading-unloading curves, (b) hardness and Young's modulus.

[0037] Figure 7The scratch acoustic emission curves of W-DLC films obtained in step S3 of the present invention at different main ion beam energies are: (a) 700 eV, (b) 800 eV, (c) 900 eV, and scratch microstructure images are: (d) 700 eV, (e) 800 eV, (f) 900 eV.

[0038] Figure 8 The friction coefficient curves of W-DLC films obtained with different main ion beam energies in step S3 of this invention are shown.

[0039] Figure 9 The surface SEM images of F-DLC films obtained in step S3 of this invention at different main ion beam energies are: (a) 700 eV, (b) 800 eV, (c) 900 eV.

[0040] Figure 10 White light interference morphology of F-DLC films obtained at different main ion beam energies in step S3 of the present invention: (a) 700 eV, (b) 800 eV, (c) 900 eV.

[0041] Figure 11 The following are the Raman spectrum peak fitting diagrams of F-DLC films obtained at different main ion beam energies in step S3 of this invention: (a) 700 eV, (b) 800 eV, (c) 900 eV.

[0042] Figure 12 XPS spectra of F-DLC films obtained at different main ion beam energies in step S3 of the present invention: (a) total XPS spectrum, (b) C1s peak fitting diagram of 700 eV sample, (c) C1s peak fitting diagram of 800 eV sample, (d) C1s peak fitting diagram of 900 eV sample.

[0043] Figure 13 The following are the F-DLC films obtained in step S3 of this invention with different main ion beam energies: (a) nanoindentation loading-unloading curves, and (b) hardness and Young's modulus.

[0044] Figure 14 The friction coefficient curves of F-DLC films obtained with different main ion beam energies in step S3 of this invention are shown.

[0045] Figure 15 The water contact angle diagrams of F-DLC films obtained with different main ion beam energies in step S3 of the present invention are as follows: (a) undoped DLC (800eV), (b) F-DLC (700eV), (c) F-DLC (800eV), (d) F-DLC (900eV). Detailed Implementation

[0046] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0047] All chemical raw materials used in the following examples and comparative examples are commercially available, and all apparatus and operations involved are conventional in the art.

[0048] Example 1

[0049] Diamond-like carbon films were prepared according to the following steps: S1. Substrate pretreatment; Cleaning process: First, the substrate is ultrasonically cleaned in acetone solution for 15 minutes to remove surface oil and organic contaminants; second, the substrate is transferred to deionized water and ultrasonically cleaned for 15 minutes to remove residual solvent and particulate impurities; then, it is ultrasonically cleaned in anhydrous ethanol for 15 minutes to further remove moisture and improve the cleanliness of the substrate surface; finally, the substrate is removed and dried with high-purity nitrogen. Ion beam cleaning: The cleaned substrate is loaded into a vacuum deposition chamber with a vacuum level better than 5.0 × 10⁻⁶. -4 Pa, a mixture of Ar and H2 gas with a volume ratio of 1:2 is introduced into the vacuum environment, and high-density argon plasma is generated by excitation with radio frequency power supply to bombard the substrate for 45 minutes to remove the surface oxide layer and adsorbed impurities. S2. Prepare a chromium transition layer; A metallic chromium transition layer was formed on the substrate surface by physical vapor deposition using a 700 eV main ion beam and 150 °C bombardment of a chromium target for 1 hour. S3. Prepare the surface modification layer; Two high-purity tungsten discs, each 15 mm in diameter and 1 mm thick, were uniformly adhered to the surface of a graphite target, 100 mm in diameter and 3 mm thick, using silver paste. After the silver paste dried, the target was placed in a deposition chamber. The graphite target was bombarded with a main ion beam at 150 °C for 3 hours to deposit a WC nanocrystalline / amorphous carbon composite structure on the surface of the metal transition layer. The main ion beam energy was 800 eV, the beam current was 72 mA, and the beam-to-energy ratio was 0.09. The substrate rotation speed was 5 rpm. During this process, a bias voltage of -100 V was applied to the substrate, and pulse modulation was performed at a frequency of 20 kHz with a pulse duty cycle of 40%. S4. Low-temperature annealing: Perform low-temperature annealing treatment in a vacuum or inert gas / hydrogen mixed atmosphere. The annealing temperature is 250℃ and the annealing time is 45min.

[0050] Example 2

[0051] Compared with Example 1, in step S3, the energy of the main ion beam is adjusted from 800 eV to 700 eV and the beam current is adjusted from 72 mA to 63 mA, while the rest remains the same as in Example 1.

[0052] Example 3

[0053] Compared with Example 1, in step S3, the energy of the main ion beam is adjusted from 800 eV to 900 eV and the beam current is adjusted from 72 mA to 81 mA, while the rest remains the same as in Example 1.

[0054] like Figure 2 The following are surface SEM images of the products obtained in Examples 1-3: Figure (a) corresponds to Example 2, Figure (b) corresponds to Example 1, and Figure (c) corresponds to Example 3. The surfaces of the products obtained in all three examples are continuous and dense, without penetrating cracks, large-area peeling, or pore defects. This indicates that in step S3, within the ion beam energy range of 700-900 eV, W doping does not damage the integrity of the DLC film formation, and modified films with continuous structures can be obtained in all cases. From the microscopic morphology, the sample prepared at 700 eV has the smoothest and most uniform surface, with only a few small protrusions and shallow pits formed by random particle deposition. As the ion beam energy increases to 800 eV, the granular undulations and local defects on the film surface increase slightly. When the energy is increased to 900 eV, the linear etching marks, granular defects, and non-uniform areas on the surface increase significantly, and the microscopic smoothness and uniformity of the film decrease significantly.

[0055] like Figure 3 The image shows the white light interference morphology of the products obtained in Examples 1-3: the arithmetic mean surface roughness Sa of the products corresponding to Examples 1-3 are all at the nanoscale. When the ion beam energy is 700 eV, 800 eV, and 900 eV, Sa is 1.145 nm, 1.469 nm, and 1.699 nm respectively. The microscopic peaks and valleys on the film surface intensify with increasing ion beam energy. The surface height distribution of the 700 eV sample is the most uniform, while the local height difference of the 900 eV sample is the most significant. This result is consistent with the observations in the SEM images above, indicating that stronger ion bombardment enhances surface sputtering, redeposition, and local perturbation, thereby exacerbating microscale fluctuations. For W-doped diamond-like carbon films, the influence of W-related components on local growth behavior is more easily amplified under high-energy conditions, resulting in more significant surface roughening. Thus, while higher energy is beneficial for film densification, it also weakens surface smoothness.

[0056] like Figure 4 The image shows the Raman spectral peak fitting diagrams of the products obtained in Examples 1-3: all three samples are at approximately 1350 cm⁻¹. -1and 1550cm -1 The presence of typical D and G peaks nearby indicates that the W-doped film retains its amorphous carbon structure. As the ion beam energy increases from 700 eV to 900 eV, the ID / IG ratio decreases from 1.23 to 1.01, and the G peak changes from 1546.85 cm⁻¹. -1 Slight redshift to 1545.11cm -1 The half-width at half-height of peak G is 163.27 cm. -1 Reduced to 155.26cm -1 This indicates that both the short-range order of the carbon network and the local vibration environment have changed.

[0057] like Figure 5 The XPS spectra of the products obtained in Examples 1-3 are shown below: As shown in Figure (a), the appearance of the W4f characteristic peak confirms the successful incorporation of W. The W contents of the three samples are 5.66 at% (700 eV), 6.2 at% (800 eV), and 7.22 at% (900 eV), respectively. From Figures (b)-(d), it can be seen that the sp4f peak in the 700 eV, 800 eV, and 900 eV samples is significantly higher than that in the 900 eV samples. 3 The components were approximately 48.3%, 49.3%, and 52.1%, respectively, sp. 2 The components were approximately 30.1%, 21.4%, and 24.2%, respectively, and both contained a certain proportion of CO and C=O bonds. Overall, as the ion beam energy increased, sp... 3 The composition shows an upward trend, sp 2 The composition was significantly suppressed compared to the 700 eV sample, with the 800 eV sample showing a lower sp. 2 The proportion is the lowest. Combined with Raman spectroscopy analysis, it can be seen that as the ion beam energy increases and the W doping amount increases, a higher proportion of sp(II) appears in the film. 3 Related structures, on the other hand, retain sp 2 They tend to become locally ordered.

[0058] like Figure 6 The figures show the mechanical properties of the products obtained in Examples 1-3. It can be seen that increasing the ion beam energy can effectively enhance the resistance to plastic deformation of the W-DLC film. Under similar loads, the indentation depth of the film significantly narrows with increasing deposition energy. Figure 6 (See Figure a in the figure); the nanohardness and Young's modulus of the 700 eV sample were 14.87 GPa and 156.73 GPa, respectively; the nanohardness and Young's modulus of the 800 eV sample were 15.78 GPa and 172.93 GPa, respectively; and the nanohardness and Young's modulus of the 900 eV sample reached the highest values ​​of 16.32 GPa and 185.25 GPa, respectively. Figure 6(See Figure b in the diagram). This illustrates that, under the condition of fixed doping with two high-purity tungsten wafers, increasing the ion beam energy is beneficial to enhancing the film's resistance to indentation and its stiffness.

[0059] like Figure 7 The images show the scratch acoustic emission curves and scratch microstructures of the products obtained in Examples 1-3. From the scratch acoustic emission curves, it can be seen that the 700 eV sample initially showed only sporadic weak abrupt changes, with a major abrupt change point appearing around approximately 43 N, corresponding to continuous failure at the scratch edge, indicating a film-substrate bonding strength of approximately 41 N. The 800 eV sample showed significant AE enhancement around approximately 37 N, corresponding to edge peeling and expansion in the microstructure, indicating a film-substrate bonding strength of approximately 36 N. The 900 eV sample showed a clear interface failure signal around approximately 32 N, subsequently rapidly entering a more severe damage stage, indicating a film-substrate bonding strength of approximately 32 N. Therefore, the film-substrate bonding strengths of W-DLC films under different ion beam energies are 41 N, 36 N, and 32 N, respectively, with the following order: 700 eV > 800 eV > 900 eV. Furthermore, the scratch microstructure images reveal that while the scratch grooves in the 700 eV sample are clear, the edges in the middle and early stages are relatively intact. Continuous peeling and significant delamination only appear in later loading stages, indicating that the film and substrate can maintain good synergistic load-bearing capacity under high external loads. The 800 eV sample shows more pronounced local damage at the scratch edges than the 700 eV sample, with continuous peeling occurring earlier, indicating a decrease in interfacial stability. The 900 eV sample exhibits significant edge damage propagation and failure concentration even earlier, corresponding to the lowest film-substrate adhesion. This suggests that within the W-DLC system, although the bulk hardness and modulus of the film increase with increasing ion beam energy, the film-substrate adhesion does not increase synchronously but gradually decreases. This phenomenon indicates that the highest bulk hardness does not necessarily mean the best interfacial adhesion; interfacial failure behavior is also controlled by multiple factors such as surface morphology, local structural uniformity, residual stress distribution, and load transfer mode.

[0060] like Figure 8 The figures show the friction coefficient curves of the products obtained in Examples 1-3. All three groups of samples exhibited brief fluctuations in the initial stage of friction, followed by a stable phase. Their stable friction coefficients were approximately 0.16, 0.18, and 0.22, respectively, with an overall trend of 700 eV < 800 eV < 900 eV. The 700 eV sample reached a stable state the fastest and had the lowest friction level, while the 900 eV sample maintained a consistently high friction level, indicating that its friction interface was relatively difficult to form a low-shear, stable contact state.

[0061] In summary, under the three energy conditions of 700, 800, and 900 eV, compared with undoped DLC, the obtained films showed significantly improved film-substrate adhesion and significantly reduced friction coefficients, thus enhancing the anti-friction performance of the films. W doping shifted the overall performance of the films from solely focusing on bulk load bearing to considering both interfacial stability and frictional performance. Considering all factors, the 800 eV energy condition was optimal, achieving the best balance between mechanical properties, adhesion properties, and frictional properties.

[0062] Example 4

[0063] Compared with Example 1, in step S3, the high-purity tungsten disc is changed to a high-purity MgF2 disc with a diameter of 15 mm and a thickness of 1 mm. The high-purity MgF2 disc is bonded to the surface of a graphite target with a diameter of 100 mm and a thickness of 3 mm using silver paste. That is, the surface modification layer is changed from WC nanocrystalline / amorphous carbon composite structure to FC nanocrystalline / amorphous carbon composite structure. All other aspects are consistent with Example 1.

[0064] Example 5

[0065] Compared with Example 2, in step S3, the high-purity tungsten disc is changed to a high-purity MgF2 disc with a diameter of 15 mm and a thickness of 1 mm. The high-purity MgF2 disc is bonded to the surface of a graphite target with a diameter of 100 mm and a thickness of 3 mm using silver paste. That is, the surface modification layer is changed from WC nanocrystalline / amorphous carbon composite structure to FC nanocrystalline / amorphous carbon composite structure. All other aspects are consistent with Example 2.

[0066] Example 6

[0067] Compared with Example 3, in step S3, the high-purity tungsten disc is changed to a high-purity MgF2 disc with a diameter of 15 mm and a thickness of 1 mm. The high-purity MgF2 disc is bonded to the surface of a graphite target with a diameter of 100 mm and a thickness of 3 mm with silver paste. That is, the surface modification layer is changed from WC nanocrystalline / amorphous carbon composite structure to FC nanocrystalline / amorphous carbon composite structure. All other aspects are consistent with Example 3.

[0068] like Figure 9The images shown are surface SEM images of the products obtained in Examples 1-3. Figure (a) corresponds to Example 5, Figure (b) corresponds to Example 4, and Figure (c) corresponds to Example 6. It can be seen that the surfaces of the three groups of samples are continuous and dense, without penetrating cracks, large-area peeling, or particle agglomeration. This indicates that complete film formation can be achieved within the ion beam energy range of 700-900 eV, and the film has good coverage of the substrate, with relatively stable overall deposition quality. From the microscopic morphology, the sample prepared at 700 eV has the smoothest surface, with only a few tiny dark spots formed by the random accumulation of deposited particles. As the ion beam energy increases to 800 eV, striped etching marks and local micro-defects begin to appear on the film surface, and the surface undulations increase. When the energy is further increased to 900 eV, the surface point defects and drag marks further increase, the microscopic uniformity of the film decreases significantly, and some areas even show a certain roughening trend.

[0069] like Figure 10 The white light interference topography images of Examples 4-6 are shown. The arithmetic mean surface roughness Sa of the three samples is at the nanoscale. As the ion beam energy increases from 700 eV to 900 eV, Sa gradually increases from 1.102 nm to 1.408 nm. The microscopic peaks and valleys on the film surface gradually intensify with increasing ion beam energy. Among them, the 700 eV sample has the most uniform surface height distribution, while the 900 eV sample has the most significant local height difference. This result is consistent with SEM observations, indicating that while increasing the ion beam energy promotes film rearrangement, it also intensifies surface micro-region re-sputtering and uneven growth, ultimately leading to an increase in roughness. Within the above energy range, the 700 eV sample has the best surface smoothness, the 800 eV sample performs well, and the 900 eV sample has the worst surface roughness.

[0070] like Figure 11 The image shows the Raman spectral peak fitting diagrams of the products obtained in Examples 4-6: All three samples show peaks around 1350 cm⁻¹. -1 and 1550cm -1 The presence of typical D and G peaks nearby indicates that the film retains the basic structural characteristics of diamond-like amorphous carbon. As the ion beam energy increased from 700 eV to 900 eV, the ID / IG ratio decreased from 1.45 to 1.15, and the G peak decreased from 1549.57 cm⁻¹. -1 Slight redshift to 1547.34cm -1 The half-height and width are 151.56cm. -1 Increased to 160.29cm -1 The overall characteristics are a decrease in ID / IG, a slight redshift of the G peak, and an increase in the full width at half maximum (FWHM). like Figure 12The XPS spectra of the products obtained in Examples 4-6 are shown below: The overall spectrum shows that C1s, O1s, F1s, and Mg1s signals were mainly detected on the sample surface, indicating that F-related components were successfully introduced into the film surface after using MgF2 as the dopant source, while retaining a small amount of Mg signal; the F contents of the three groups of samples were 2.31 at%, 3.07 at%, and 4.19 at%, respectively; the C1s peak results show that C1s... 3 The components were 46.3%, 49.3%, and 50.5%, respectively, C sp 2 The components were 27.2%, 32.5%, and 32.1%, respectively; the CO components were 22.1%, 11.1%, and 11.3%, respectively; and the C=O components were 4.4%, 7.1%, and 6.1%, respectively. Overall, with increasing ion beam energy, the F content increased, and the sp content... 3 The composition has been improved.

[0071] like Figure 13 The mechanical property test results for the products obtained in Examples 4-6 are shown in the figure. Under the same maximum load, the indentation depth of the film gradually decreases with increasing ion beam energy, with the 700 eV sample showing the largest indentation depth and the 900 eV sample showing the smallest. This indicates that increasing the ion beam energy can significantly enhance the ability of the F-DLC film to resist plastic deformation. Quantitative test results show that the nanohardness of the 700, 800, and 900 eV samples are 14.29 GPa, 14.61 GPa, and 16.09 GPa, respectively, and the corresponding Young's moduli are 146.26 GPa, 163.75 GPa, and 187.69 GPa, respectively. Both the hardness and modulus of the film show a monotonically increasing trend with increasing ion beam energy. This result is highly consistent with the microstructure changes revealed by Raman and XPS characterization.

[0072] like Figure 14 The friction coefficient curves of the products obtained in Examples 4-6 are shown: the stable friction coefficients of the 700, 800, and 900 eV samples are approximately 0.16, 0.17, and 0.19, respectively, showing an overall increasing trend with increasing ion beam energy, indicating that the F-DLC film prepared at lower ion beam energies has better friction-reducing properties. This result is consistent with the surface morphology analysis. As the ion beam energy increases from 700 eV to 900 eV, the number of streaks and local defects on the film surface increases, and the roughness increases from 1.102 nm to 1.408 nm. Surface roughening exacerbates the non-uniformity of actual contact and local stress concentration, which is not conducive to the formation of a stable, low-shear friction interface. Therefore, although the 900 eV sample is more dense, it has the highest friction coefficient.

[0073] like Figure 14The diagram shows the water contact angles of the products obtained in Examples 4-6: the water contact angle of Comparative Example 1 is 84.1°; after the introduction of F, the contact angles of the 700, 800, and 900 eV samples increased to 92.7°, 95.5°, and 99.8°, respectively, and gradually increased with increasing ion beam energy, indicating that F doping can significantly improve the hydrophobicity of the DLC film surface. This result is directly related to the change in F content. As the ion beam energy increased from 700 eV to 900 eV, the F content in the F-DLC film increased from 2.31 at% to 4.19 at%. After F forms the CF phase key, it can significantly reduce the surface polarity and surface free energy, weakening the interaction between water molecules and the surface. Therefore, the droplets tend to remain spherical, exhibiting a larger contact angle. In addition, with increasing ion beam energy, the sp in the film... 3 The increase in related structures and the decrease in oxygen-containing groups, especially CO components, on the surface indicate that the film surface tends to be dense and less active. The reduction in polar oxygen-containing groups and the increase in low-surface-energy fluorine-containing structures on the surface work together to further enhance the surface hydrophobic behavior.

[0074] Example 7

[0075] Compared with Example 1, (1) the metal transition layer in step S2 includes a multilayer film structure with alternating high-purity chromium layers and tungsten nanofilm layers, and chromium nanofilm layers. The specific operation is adjusted as follows: the chromium target is bombarded with a main ion beam with an energy of 800 eV and the surface of the high-purity chromium layer under deposition is simultaneously bombarded with an auxiliary ion beam with an energy of 100 eV. The deposition is carried out at 150°C for 45 min. Then, the tungsten target and the chromium target are bombarded alternately with a main ion beam with an energy of 800 eV to form a multilayer film structure with alternating tungsten nanofilm layers and chromium nanofilm layers. Each nanolayer is deposited at 150°C for 6 min. One tungsten nanofilm layer and one chromium nanofilm layer constitute one repeating unit. The multilayer film structure The structure has 8 repeating units; (2) After step S2 is completed, a gradient functional layer is deposited. The preparation operation is as follows: the carbon film is formed on the surface of the metal transition layer by sputtering carbon particles by bombarding the graphite target with the main ion beam. At the same time, the surface of the growing carbon film is continuously bombarded by the auxiliary ion beam. The main ion beam and the auxiliary ion beam are controlled independently. The energy of the main ion beam is 800eV, the energy of the auxiliary ion beam is 88eV, and the ratio of the energy of the main ion beam to the energy of the auxiliary ion beam is 1:0.11. During this process, a bias voltage of -100V is applied to the substrate and pulse modulation is performed at a frequency of 20kHz. The pulse duty cycle is 40%. The rest is consistent with Example 1.

[0076] Example 8

[0077] Compared with Example 7, when depositing the gradient functional layer, the energy of the main ion beam was 700 eV and the energy of the auxiliary ion beam was 77 eV, while the rest remained the same as in Example 7.

[0078] Example 9

[0079] Compared with Example 7, when depositing the gradient functional layer, the energy of the main ion beam is 900 eV and the energy of the auxiliary ion beam is 99 eV, while the rest are the same as in Example 7.

[0080] Example 10

[0081] Compared with Example 7, (1) the metal transition layer in step S2 includes a high-purity chromium layer and a single-layer chromium-tungsten alloy layer. The specific operation is adjusted as follows: the chromium target is bombarded with a main ion beam of 800 eV and the surface of the high-purity chromium layer under deposition is simultaneously bombarded with an auxiliary ion beam of 100 eV. The deposition is carried out at 150°C for 45 min. Then, the chromium-tungsten alloy target is bombarded with a main ion beam of 800 eV and the surface of the chromium-tungsten alloy layer under deposition is simultaneously bombarded with an auxiliary ion beam of 100 eV. The deposition is carried out at 150°C for 50 min. (2) After step S2 is completed, the deposition gradient work The energy layer was prepared by bombarding a graphite target with a main ion beam to sputter carbon particles onto the surface of a metal transition layer to form a carbon film. Simultaneously, an auxiliary ion beam continuously bombarded the growing carbon film surface. The main ion beam and the auxiliary ion beam were controlled independently. The energy of the main ion beam was 800 eV, and the energy of the auxiliary ion beam was 88 eV. The energy ratio of the main ion beam to the auxiliary ion beam was 1:0.11. During this process, a bias voltage of -100 V was applied to the substrate and pulsed at a frequency of 20 kHz with a pulse duty cycle of 40%. All other procedures were consistent with those in Example 1.

[0082] Example 11

[0083] Compared with Example 10, when depositing the gradient functional layer, the energy of the main ion beam is 800 eV, the energy of the auxiliary ion beam is 120 eV, the energy ratio of the main ion beam to the auxiliary ion beam is 1:0.15, and all other aspects are the same as in Example 10.

[0084] Example 12

[0085] Compared with Example 10, when depositing the gradient functional layer, the energy of the main ion beam is 800 eV, the energy of the auxiliary ion beam is 80 eV, the energy ratio of the main ion beam to the auxiliary ion beam is 1:0.10, and all other aspects are consistent with Example 10.

[0086] The preparation conditions and various properties of the products obtained in Comparative Examples 7-12 are listed in Table 1 for comparison with those in Example 1 and Comparative Example 1.

[0087]

[0088] As shown in Table 1: Based on the scheme shown in Example 1, by scientifically designing the structure of the metal transition layer and adding a gradient transition layer, a multi-layer structure of "metal transition layer - gradient functional layer - surface modification layer" is constructed. While ensuring the high mechanical properties of the substrate, the film-substrate bonding force is further improved. It plays a bridging role between the metal transition layer and the surface modification layer. The synergistic effect of the multi-layer structure also helps to solve the interface abruptness problem and helps to further extend its service life under harsh working conditions.

[0089] Comparative Example 1 Compared with Example 1, high-purity tungsten wafers are not introduced in step S3, while the rest remains the same as in Example 4.

[0090] Test results show that the arithmetic mean surface roughness Sa of the obtained DLA film is 1.548 nm, the nanohardness is 16.87 GPa, the Young's modulus is 178.55 GPa, the film-substrate adhesion is 24 N, and the coefficient of friction is 0.22.

[0091] Comparative Example 2 Compared to Example 1, the number of high-purity tungsten wafers in step S3 was adjusted to one, while the rest remained the same as in Example 1. Tests showed that the W doping level in the surface modification layer was 2.61 at%.

[0092] Comparative Example 3 Compared to Example 1, the number of high-purity tungsten wafers in step S3 was adjusted to 4, while the rest remained the same as in Example 1. Tests showed that the W doping level in the surface modification layer was 16.73 at%.

[0093] XPS high-resolution analysis showed that the corresponding sp values ​​for Comparative Example 2 (W doping amount 2.61 at%), Example 1 (W doping amount 6.2 at%), and Comparative Example 3 (W doping amount 16.73 at%) were... 3 The components were 52.3%, 49.3%, and 46.4%, respectively, sp. 2 The compositions were 21.4%, 21.4%, and 23.1%, respectively, and all contained a certain proportion of CO and C=O bonds. Overall, as the W doping concentration increased, sp... 3 The composition continued to decrease while sp 2The slight increase in component content indicates that a higher W content weakens the highly cross-linked characteristics of the carbon network, causing the film to gradually evolve towards a structure with lower cross-linking degree. Furthermore, by testing the hardness and modulus of the film, it was found that when the W content was 2.61 at%, 6.2 at%, and 16.73 at%, the nanohardness was 15.05 GPa, 15.78 GPa, and 13.26 GPa, respectively, and the corresponding Young's moduli were 169.27 GPa, 172.93 GPa, and 149.58 GPa, respectively. Among them, the sample with a moderate doping amount of 6.2 at% shown in Example 1 exhibited the best bulk mechanical properties. The coefficients of friction were approximately 0.20, 0.18, and 0.20, respectively, showing an overall trend of first decreasing and then increasing, with the sample in Example 1 showing the lowest coefficient. It is evident that the improvement in DLC film performance by W doping does not increase infinitely with increasing content, but rather exhibits a clear optimal window characteristic. Only under moderate doping conditions can the unified optimization of hardness improvement and friction reduction be achieved, which further illustrates the importance of precise control of W content for obtaining high-performance W-DLC films.

[0094] Comparative Example 4 Compared with Example 4, the number of high-purity MgF2 discs was adjusted to 2, while the rest remained the same as in Example 1.

[0095] Comparative Example 5 Compared with Example 4, the number of high-purity MgF2 discs was adjusted to 4, while the rest remained the same as in Example 1.

[0096] Testing revealed that the F doping levels in the products of Comparative Examples 4 and 5 were 7.92 at% and 18.54 at%, respectively. XPS analysis showed that when the F content was 3.07 at%, 7.92 at%, and 18.54 at%, the corresponding C1s peak results indicated Csp... 3 The components were 49.3%, 47.5%, and 46.7%, respectively, with Csp 2 The components were 32.5%, 32.4%, and 35.5%, respectively; the CO components were 11.1%, 13.8%, and 11.6%, respectively; and the C=O components were 7.1%, 6.3%, and 6.2%, respectively. With increasing F doping concentration, sp... 3 The composition decreased while sp 2The overall increase in component content indicates that the higher F content has a more significant weakening effect on the continuous highly cross-linked carbon network. Hardness, Young's modulus, and friction coefficient test results show that the samples with F contents of 3.07 at%, 7.92 at%, and 18.54 at% have nanohardnesses of 14.61 GPa, 13.78 GPa, and 12.91 GPa, respectively, and corresponding Young's moduli of 163.75 GPa, 152.93 GPa, and 135.76 GPa, respectively. Both the film hardness and elastic modulus show a monotonically decreasing trend with increasing F doping content; the friction coefficients are approximately 0.17, 0.14, and 0.20, respectively. Water contact angle tests showed that the water contact angle of the undoped DLC film (Comparative Example 1) was only 84.1° (weakly hydrophilic), while after F doping, the hydrophobicity of the film showed a significant monotonic increasing trend with increasing F content: the water contact angles of samples with doping amounts of 3.07at%, 7.92at%, and 18.54at% increased to 95.5°, 101.9°, and 108.0°, respectively, with the highly doped samples achieving good hydrophobic effects. As the F doping amount increased from 3.07at% to 18.54at%, the fluorine content in the film surface gradually increased. After F forms the CF phase key, it can significantly reduce surface polarity and surface free energy, weakening the interaction between water molecules and the surface, thus continuously increasing the contact angle. In summary, a moderate amount of F doping can achieve a good balance between surface low energy and carbon network stability, thus obtaining the best friction reduction performance. As the amount of F doping continues to increase, the 18.54 at% sample has the largest water contact angle and exhibits the best hydrophobic performance, but it is not conducive to taking into account both mechanical properties and friction reduction performance, and cannot achieve the goal of extending the overall service performance.

[0097] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions, and variations to the above embodiments within the scope of the present invention. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of the different embodiments or examples.

Claims

1. A method for preparing diamond-like carbon thin films based on ion beam energy modulation, characterized in that: The following steps are included: S1. Substrate pretreatment, including cleaning treatment for removing contaminant layers from the substrate surface and ion beam cleaning for obtaining atomically clean surfaces; S2. Prepare a metal transition layer by bombarding a chromium target and / or a tungsten target with a main ion beam of 700-900 eV and a temperature of 80-220℃ on the substrate surface using a physical vapor deposition process. S3. Prepare a surface modification layer by using a graphite target as the carbon source and introducing fluorine- or tungsten-containing dopant sources. Deposit the FC nanocrystalline / amorphous carbon composite structure or WC nanocrystalline / amorphous carbon composite structure on the surface of the metal transition layer by bombarding the graphite target with a main ion beam at 100-300℃ for 2-4 hours. The main ion beam energy is 700-900 eV, the beam current is 63-81 mA, and the beam current-to-energy ratio is 0.

09. S4. Low-temperature annealing: Perform low-temperature annealing treatment in a vacuum or inert gas / hydrogen mixed atmosphere. The annealing temperature is 200-400℃ and the annealing time is 0.5-3h.

2. The method for preparing diamond-like carbon thin films based on ion beam energy regulation according to claim 1, characterized in that: A gradient functional layer is first deposited on the metal transition layer, and then a surface modification layer is prepared. The preparation operation of the gradient functional layer is as follows: carbon particles are sputtered onto the surface of the metal transition layer by bombarding the graphite target with a main ion beam to form a carbon film, while the surface of the growing carbon film is continuously bombarded with an auxiliary ion beam. The main ion beam and the auxiliary ion beam are controlled independently. The energy of the main ion beam is 700-900 eV, the energy of the auxiliary ion beam is 70-135 eV, and the energy ratio of the main ion beam to the auxiliary ion beam is 1:(0.10-0.15). Preferably, the energy of the main ion beam is 800 eV and the energy of the auxiliary ion beam is 88 eV, with the energy ratio of the main ion beam to the auxiliary ion beam being 1:0.

11.

3. The method for preparing diamond-like carbon thin films based on ion beam energy regulation according to claim 2, characterized in that: The specific preparation method of the gradient functional layer can be selected from either of the following two methods: Method 1: The gradient functional layer is divided into three layers, namely bottom layer, middle layer and top layer, according to the distance from the metal transition layer from near to far. The main ion beam energy is 700 eV when preparing the bottom layer, 800 eV when preparing the middle layer and 900 eV when preparing the top layer. Method 2 involves linearly increasing the main ion beam energy from 700 eV to 900 eV and then linearly decreasing it from 900 eV to 700 eV during the fabrication of the entire gradient functional layer.

4. The method for preparing diamond-like carbon thin films based on ion beam energy regulation according to claim 2 or 3, characterized in that: When fabricating graded functional layers, the main ion beam emission source is a Kaufman type or radio frequency (RF) ion source with a flux density of 2-5 mA / cm². 2 The auxiliary ion beam emission source adopts an End-Hall type ion source that points directly to the substrate surface, and its ion incident angle is at an angle of 0-60° with the substrate normal.

5. The method for preparing diamond-like carbon thin films based on ion beam energy regulation according to claim 1, characterized in that: In step S3, the preparation operation of the WC nanocrystalline / amorphous carbon composite structure is as follows: the doping source is a high-purity tungsten wafer, which is fixed on the surface of a graphite target. The amount of tungsten doping is controlled by adjusting the coverage area of ​​the high-purity tungsten wafer on the graphite target.

6. The method for preparing diamond-like carbon thin films based on ion beam energy modulation according to claim 5, characterized in that: In step S3, the tungsten content in the WC nanocrystalline / amorphous carbon composite structure is 3-10 at%; Preferably, in step S3, the main ion beam energy is 800 eV, the beam current is 72 mA, and the tungsten content in the WC nanocrystalline / amorphous carbon composite structure is 6.2 at.

7. The method for preparing diamond-like carbon thin films based on ion beam energy modulation according to claim 1, characterized in that: In step S3, the preparation operation of the FC nanocrystalline / amorphous carbon composite structure is as follows: the doping source is a high-purity MgF2 sheet or a high-purity PTFE sheet, the high-purity MgF2 sheet or high-purity PTFE sheet is fixed on the surface of the graphite target, and the doping amount of fluorine is controlled by adjusting the coverage area of ​​the high-purity MgF2 sheet or high-purity PTFE sheet on the graphite target.

8. The method for preparing diamond-like carbon thin films based on ion beam energy modulation according to claim 7, characterized in that: In step S3, the fluorine content in the FC nanocrystalline / amorphous carbon composite structure is 5-10 at%; Preferably, in step S3, the main ion beam energy is 800 eV, the beam current is 72 mA, and the fluorine content in the FC nanocrystalline / amorphous carbon composite structure is 7.92 at.

9. The method for preparing diamond-like carbon thin films based on ion beam energy modulation according to claim 2, characterized in that: In step S2, the metal transition layer comprises a high-purity chromium layer with a thickness of 50-200 nm and a chromium-tungsten alloy layer with a thickness of 100-300 nm. The chromium-tungsten alloy layer is a single-layer chromium-tungsten alloy layer or a multilayer film structure with alternating tungsten nanofilm layers and chromium nanofilm layers. In the preparation process shown in steps S3 and S4, a bias voltage of -50V to -200V is applied to the substrate and pulse modulation is performed at a frequency of 10-100kHz, with a pulse duty cycle of 20%-80%. Preferably, during the deposition of the high-purity chromium layer, a main ion beam with an energy of 800 eV is used to bombard the chromium target and an auxiliary ion beam with an energy of 100 eV is used to simultaneously bombard the surface of the high-purity chromium layer during deposition. Preferably, during the deposition of a single-layer chromium-tungsten alloy layer, a main ion beam with an energy of 800 eV is used to bombard the chromium-tungsten alloy target, and an auxiliary ion beam with an energy of 100 eV is used to simultaneously bombard the surface of the deposited chromium-tungsten alloy layer. Preferably, during the deposition of the multilayer film structure, a main ion beam with an energy of 800 eV is used to alternately bombard a tungsten target and a chromium target to form tungsten nanofilms and chromium nanofilms arranged alternately with 5-10 periodic repetitions.

10. The method for preparing diamond-like carbon thin films based on ion beam energy modulation according to claim 1, characterized in that: In step S1, the specific operation of ion beam cleaning is as follows: a mixture of Ar and H2 with a volume ratio of 1:(1-4) is introduced into the vacuum environment, and a high-density plasma is generated by excitation using a radio frequency power supply to bombard the substrate with plasma for 30-60 minutes.

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