Zr-dlc gradient composite film with multi-environment friction adaptability and preparation method and application thereof

Abstract

The application discloses a Zr-DLC gradient composite film with multi-environment friction adaptability and a preparation method and application thereof, and belongs to the technical field of surface engineering and film material, wherein the film is composed of four-layer gradient composite structures of a Ti bonding layer, a TiN transition layer, an undoped DLC buffer layer and a Zr modified DLC functional layer from the substrate outward; Zr elements are distributed in the amorphous carbon network in the form of Zr-C chemical bonds to control the stability of the carbon network structure; the application realizes accurate control of the Zr content in the functional layer by adopting a C-Zr splicing target and adjusting the spatial position of the substrate; the prepared film shows excellent friction reduction and wear resistance in deionized water environment, diesel lubrication and complex environments such as simulated lunar dust, effectively solves the problem that pure DLC film is prone to wear failure under complex medium conditions, and is suitable for wear protection of the surfaces of aerospace equipment, precision transmission parts and complex environment friction pairs.

Description

Technical Field

[0001] This invention belongs to the technical field of surface engineering and thin film materials, specifically relating to a Zr-DLC gradient composite thin film with multi-environment friction adaptability, its preparation method and application. Background Technology

[0002] Friction and wear are among the major causes of failure in key components of high-end equipment. Diamond-like carbon (DLC) films, with their advantages of high hardness, low coefficient of friction, and excellent chemical stability, have been widely used for wear protection in aerospace equipment, precision transmission components, and mechanical friction pairs. However, as service environments evolve from traditional dry friction to more complex conditions such as water-based liquid media, oil-based liquid lubrication, and high-hardness particle contamination, pure DLC films are prone to frictional performance degradation and wear failure due to high residual stress, limited load-bearing capacity, and insufficient environmental adaptability. For example, in water-based liquid environments, water molecule adsorption and interfacial chemical interactions weaken frictional stability; in diesel lubrication environments, pure DLC films lack effective load-bearing structures, making it difficult to form a stable transfer film; and in simulated lunar dust environments, high-hardness particles cause severe three-body abrasive wear. Therefore, improving the adaptability of DLC films to various environmental friction conditions is an important direction for expanding their engineering applications.

[0003] Elemental doping is considered an important approach to improve the structure and performance of DLC films. In existing studies on metal-modified DLCs, non-carbide-forming elements such as Cu and Ag mainly reduce friction by adjusting the carbon network structure and improving interfacial lubrication behavior, but their effect on film load-bearing capacity and resistance to abrasive wear is limited. While carbide-forming elements such as Mo and Cr can enhance film hardness and wear resistance, related studies are mostly focused on specific temperatures or oil-lubricated environments, and problems such as oxidative wear and insufficient interfacial stability may still exist in water-based liquid phase environments. Zr, as a typical carbide-forming element, can regulate the DLC structure by forming a hard carbide phase with the carbon matrix. However, existing research on Zr-doped DLCs mainly focuses on performance evaluation under single environments, with limited research on the synergistic adaptability to multiple environments such as water-based liquid phases, diesel lubrication, and hard particle wear. Furthermore, existing research still lacks sufficient understanding of the influence of different Zr contents on the stability of the carbon network structure and the frictional behavior in complex environments of DLC films, especially lacking systematic research on the control window for low-content Zr and the mechanism of structural instability caused by excessive Zr. In addition, traditional multi-target co-sputtering processes usually require multiple target sources to be adjusted independently, and the coupling of deposition parameters is relatively complex, which is not conducive to the continuous control of Zr content and the stable control of film composition.

[0004] Therefore, it is necessary to develop a multi-environmentally adaptable DLC film based on low Zr content and its preparation method. By rationally controlling the Zr content and combining it with a gradient multilayer structure design, the structural stability of the film and its tribological properties under complex environments can be improved, thereby meeting the stable service requirements of key moving parts under different friction conditions such as deionized water, diesel lubrication and hard particle wear. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a Zr-DLC gradient composite film with multi-environmental friction adaptability, its preparation method and application, so as to solve the problems mentioned in the background art or achieve better technical effects.

[0006] In order to solve the above-mentioned technical problems, the inventors derived the technical solution of the present invention through practice and summary. The present invention discloses a Zr-DLC gradient composite film with multi-environmental friction adaptability. The Zr-DLC gradient composite film is deposited on the surface of a substrate. The Zr-DLC gradient composite film includes, from the substrate outward, the following layers in sequence: Ti bonding layer (1), TiN transition layer (2), undoped DLC buffer layer (3) and Zr modified DLC functional layer (4).

[0007] In the Zr-modified DLC functional layer (4), the atomic percentage of Zr element is 2.6 at.%~4.7 at.%, and Zr element is distributed in the amorphous carbon network in the form of Zr-C chemical bonding.

[0008] Furthermore, in the Zr-modified DLC functional layer (4), the Zr element is dispersed at the atomic level and the stability of the amorphous carbon network is controlled by the Zr-C bonding structure. The film exhibits a single amorphous phase structure under a transmission electron microscope, with no obvious nanocrystals or second phase particles precipitated.

[0009] Furthermore, the Zr-modified DLC functional layer (4) exhibits a friction coefficient ≤0.19 and a wear rate ≤1.35×10⁻⁶ in deionized water, diesel lubrication, and simulated lunar dust abrasive environments. -5 mm 3 / (N·m).

[0010] Furthermore, the thickness of the Ti bonding layer (1) is 50~100nm, the thickness of the TiN transition layer (2) is 100~300nm, the thickness of the undoped DLC buffer layer (3) is 100~500nm, and the thickness of the Zr modified DLC functional layer (4) is 1.0~3.0μm.

[0011] Furthermore, the preparation method of any of the above-described Zr-DLC gradient composite films with multi-environmental friction adaptability includes the following steps:

[0012] S1: After cleaning and drying the substrate, it is clamped onto the rotating base frame of the coating chamber;

[0013] S2: Evacuate the coating chamber until the background vacuum level is below 5.0 × 10⁻⁶. -3 Pa, and heated to the deposition temperature;

[0014] S3: Introduce argon gas, turn on the carbon target, titanium target and C-Zr splicing target respectively for pre-sputtering, and then turn them off; Introduce argon gas again, turn on the ion source and apply bias voltage to perform ion etching and cleaning on the substrate;

[0015] S4: Introduce argon gas, turn on the titanium target, and sputter to deposit a Ti bonding layer on the substrate surface (1).

[0016] S5: Introduce argon and nitrogen gas, keep the titanium target open, and perform reaction sputtering to deposit a TiN transition layer (2) on the Ti bonding layer (1).

[0017] S6: Introduce argon and acetylene, turn on the carbon target, and deposit an undoped DLC buffer layer (3) on the TiN transition layer (2).

[0018] S7: Introduce argon and acetylene, turn on the C-Zr splicing target, and deposit a Zr-modified DLC functional layer (4) with a Zr atomic percentage of 2.6 at.%~4.7 at.% on the DLC buffer layer (3) by adjusting the spatial position of the base frame in the deposition chamber.

[0019] S8: After deposition, turn off the power and gas supply, and remove the sample after cooling to the specified temperature.

[0020] Furthermore, in S3, the revolution speed of the rotating base is adjusted to 3~5 rpm, the rotation speed is adjusted to 2~5 rpm, the ion source voltage is adjusted to 500~1200V, the substrate bias voltage is adjusted to -1000V, and the etching and cleaning time is adjusted to 10~20min.

[0021] Furthermore, in S4, the deposition conditions of the Ti bonding layer (1) are: gas pressure 0.5~0.8Pa, titanium target sputtering power 400~600W, substrate bias voltage -80~-120V, and deposition time 10~30min.

[0022] Furthermore, in S5, the deposition time of the TiN transition layer (2) is 60 to 120 minutes; in S6, the deposition time of the undoped DLC buffer layer (3) is 20 to 40 minutes.

[0023] Furthermore, in S7, the C-Zr splicing target is composed of carbon target and zirconium target splicing, and the arrangement of the zirconium target makes a continuous gradient of zirconium / carbon ion beam flux along the length of the target; the deposition conditions of the Zr modified DLC functional layer (4) are: gas pressure 0.6~0.7Pa, substrate bias voltage -100V, C-Zr splicing target splicing power 800~1000W, and deposition time 120~200min.

[0024] Furthermore, the Zr-DLC gradient composite film with multi-environment friction adaptability described above can be used for wear-resistant protection of surfaces in aerospace equipment, precision transmission components, or complex environmental friction pairs.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] (1) The Zr-DLC gradient composite film prepared by the present invention has a gradient composite structure of substrate / Ti bonding layer / TiN transition layer / DLC buffer layer / Zr-DLC functional layer; through the multi-layer synergy of Ti bonding layer, TiN transition layer, DLC buffer layer and Zr-DLC functional layer, the internal stress of the film is effectively relieved, the film-substrate bonding strength and overall structural stability are significantly improved, and the defects of traditional DLC film being easy to peel off are overcome.

[0027] (2) This invention controls the Zr content within the range of 2.6 at.% to 4.7 at.%, enabling Zr to effectively participate in the regulation of the carbon-based network structure, forming a stable Zr-C bonded structure and a nanoscale zirconium-based reinforced region, thereby improving the stability of the amorphous carbon network structure. Compared with the structural imbalance and decreased friction performance caused by further increasing the Zr content, the Zr doping range defined by this invention can better balance the film's load-bearing capacity and friction stability, realizing the transformation from simple element addition to optimized regulation of the carbon network structure. Based on the above structural regulation, the prepared Zr-modified DLC film exhibits good friction adaptability under different friction environments such as deionized water, diesel lubrication, and simulated lunar dust. In the deionized water environment, it can improve the film's friction stability and wear resistance; in the diesel lubrication environment, it can improve the load-bearing and friction-reducing anti-wear performance of the friction interface and facilitate the formation of a stable transfer film; in the simulated lunar dust environment, it can improve the film's ability to resist the plowing and cutting action of hard particles, thereby achieving comprehensive friction protection against water-based liquid media, oil-based liquid lubrication media, and solid particle abrasive media.

[0028] (3) This invention uses physical vapor deposition (PVD) to prepare Zr-modified DLC thin films. By adjusting the relative position of the substrate within the deposition region, the amount of Zr introduced is controlled, thereby regulating the composition of the Zr-modified DLC functional layer. Combined with a Ti / TiN / DLC / Zr-DLC gradient multilayer structure design, a structurally stable functional thin film is obtained. The preparation method is compatible with existing magnetron sputtering equipment, requires no complex post-processing, has a simple process flow, and facilitates stable film preparation. It can be used for wear-resistant protection of aerospace equipment, precision transmission components, and friction pairs in complex environments. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the gradient multilayer composite DLC thin film structure prepared in this invention;

[0030] Figure 2 The image shows the XPS fitting results of the Zr peak of the 4.7 at.% Zr modified DLC film prepared in Example 3 of this invention.

[0031] Figure 3 TEM image of the 4.7 at.% Zr modified DLC film prepared in Example 3 of this invention;

[0032] Wherein: (a) is a high-resolution transmission electron microscope (HRTEM) image; (b) is a selected area electron diffraction (SAED) image;

[0033] Figure 4 Microscopic images of the wear marks on the surfaces of the pure DLC film (a) prepared in Comparative Example 1 and the 4.7 at.% Zr modified DLC film (b) prepared in Example 3 after friction testing in a simulated lunar dust environment.

[0034] The attached figures are labeled as follows:

[0035] 1. Ti bonding layer;

[0036] 2. TiN transition layer;

[0037] 3. DLC buffer layer;

[0038] 4. Zr-DLC functional layer. Detailed Implementation

[0039] To make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to specific examples.

[0040] Unless otherwise specified, all raw materials or reagents used in the following examples are commercially available products.

[0041] The thin films of the present invention are prepared by physical vapor deposition (PVD) magnetron sputtering technology; the following examples use 9Cr18 stainless steel (surface roughness Ra < 30nm) as the substrate material; the purity of the target materials used are: Ti target 99.7%, graphite C target 99.99%, and Zr target 99.2%.

[0042] A Zr-DLC gradient composite film with multi-environmental friction adaptability is deposited on the surface of 9Cr18 or other metal substrates, such as... Figure 1 As shown, the composite film consists of a Ti bonding layer 1, a TiN transition layer 2, an undoped DLC buffer layer 3, and a Zr-modified DLC functional layer 4, forming a four-layer gradient composite structure from the substrate outwards.

[0043] In the Zr-modified DLC functional layer 4, the atomic percentage content of Zr element is between 2.6 at.% and 4.7 at.%, and the microstructure of the film is mainly composed of an amorphous carbon network. The stability of the carbon network is controlled through Zr-C bonding structure and local Zr-based reinforcement structure.

[0044] A method for preparing Zr-DLC gradient composite thin films with multi-environmental tribological adaptability is proposed. The method employs physical vapor deposition magnetron sputtering technology, utilizing a pure Ti target and a C-Zr spliced ​​target composed of pure carbon and pure zirconium. By adjusting the relative spatial position of the substrate in the deposition chamber, the substrate receives Zr sputtered particles of different contents, thereby achieving one-time deposition of thin films with different Zr doping gradients.

[0045] The preparation steps are as follows:

[0046] (1) Matrix pretreatment and cleaning:

[0047] The 9Cr18 substrate was sequentially immersed in acetone, anhydrous ethanol, and deionized water, and ultrasonically cleaned for 20 minutes in each case to remove surface oil and impurities. Then, it was dried with dry nitrogen gas and clamped onto the rotating frame of the coating machine from high to low according to the height of the target material.

[0048] (2) Vacuuming and heating:

[0049] Close the coating chamber and evacuate until the background vacuum level is below 5.0 × 10⁻⁶. -3 Pa, turn on the heater on the inner wall of the cavity to raise the temperature to and maintain it at 180°C, which is the deposition temperature;

[0050] (3) Target pre-sputtering and ion etching cleaning:

[0051] Argon gas with a purity of 99.99% was introduced into the chamber, and its flow rate was adjusted to stabilize the vacuum chamber pressure at 0.5~0.8Pa. The power supplies for the C target, Ti target and C-Zr splicing target were turned on respectively, and pre-sputtered at 500W power for 5 minutes to clean the target surface, and then the target power supply was turned off.

[0052] After adjusting the Ar gas flow rate to stabilize the vacuum chamber pressure at 0.4~0.6 Pa, turn on the auxiliary anode layer ion source, set the voltage to 1000V, and simultaneously apply a -1000V high bias voltage to the substrate, utilizing Ar... + The substrate surface was cleaned by glow discharge etching for 15 minutes; during this period, the substrate carrier rotated at a speed of 2~5 rpm for both revolution and rotation.

[0053] (4) Deposited Ti bonding layer:

[0054] Maintain the vacuum chamber pressure at 0.5~0.8Pa, set the Ti target sputtering power to 500W, the substrate bias voltage to -100V, and the deposition time to 10~30min, and deposit a Ti bonding layer 1 with a thickness of 50~100nm on the substrate surface;

[0055] (5) Deposition of TiN transition layer:

[0056] Keeping the bias voltage at -100V and the Ti target power at 500W constant, argon (Ar) and nitrogen (N2) gas are simultaneously introduced into the chamber to maintain the vacuum chamber pressure at 0.5~0.8Pa. The deposition time is 60~120min, and a TiN transition layer 2 with a thickness of 100~300nm is generated on the above Ti bonding layer.

[0057] (6) Deposition of undoped DLC buffer layer:

[0058] Close the nitrogen flow valve, introduce Ar gas and acetylene (C2H2) gas, maintain the vacuum chamber pressure at 0.6~0.7Pa, turn on the C target, control the power at 500W, the bias voltage at -100V, and the deposition time at 20~40min to generate an undoped DLC buffer layer 3 with a thickness of 100~500nm.

[0059] (7) Deposition of Zr-modified DLC functional layer:

[0060] Ar and C2H2 gases were introduced to maintain the vacuum chamber pressure at 0.6~0.7 Pa and the bias voltage at a constant -100 V. The C-Zr splicing target was turned on, the splicing power was set to 800 W, and the deposition time was 120~200 min. By adjusting the relative spatial position of the substrate in the deposition chamber, the substrate received different fluxes of Zr spliced ​​particles, and finally a Zr-modified DLC functional layer 4 with a Zr atomic percentage in the range of 2.6 at.%~4.7 at.% was obtained on the DLC buffer layer. The thickness of the Zr-modified DLC functional layer was 1.5~2.3 μm.

[0061] The C-Zr spliced ​​target is a rectangular target structure formed by splicing together diagonally cut triangular pure carbon target and pure zirconium target. The cross section of the pure zirconium gradually narrows from one end of the target to the other end, so that a continuous zirconium / carbon ion beam flux gradient is formed along the length of the target during the deposition process.

[0062] (8) End of sedimentation:

[0063] Turn off all target power supplies, heaters, bias power supplies, and Ar and C2H2 gas inlet valves. After the chamber temperature cools down to the specified temperature (specified temperature ≤ 50℃), open the door to take samples, thus completing the entire preparation process.

[0064] While keeping the main parameters such as deposition power, gas pressure, and time unchanged in the above preparation process, the deposition flux of Zr element is changed by adjusting only the relative position of the substrate in the deposition chamber, thereby preparing examples and comparative examples with different Zr contents.

[0065] Example 1

[0066] A method for preparing a Zr-DLC gradient composite film with multi-environmental friction adaptability, wherein in step (7) of the above process, a lower Zr introduction amount is obtained by adjusting the substrate position, and the Zr content of the functional layer of the resulting film is 2.6 at.%.

[0067] Example 2

[0068] A method for preparing a Zr-DLC gradient composite film with multi-environmental friction adaptability, wherein in step (7) of the above process, the substrate position is adjusted to obtain a moderate Zr introduction amount, and the Zr content of the functional layer of the resulting film is 3.3 at.%.

[0069] Example 3

[0070] A method for preparing a Zr-DLC gradient composite film with multi-environmental friction adaptability, wherein in step (7) of the above process, the substrate position is adjusted to obtain a higher Zr introduction amount, and the Zr content of the functional layer of the resulting film is 4.7 at.%.

[0071] Comparative Example 1 (Pure DLC)

[0072] During the functional layer deposition stage, without activating the C-Zr splicing target, deposition was performed solely using a carbon source, resulting in a thin film with a Zr content of 0 at.%.

[0073] Comparative Example 2

[0074] A method for preparing a Zr-DLC gradient composite film, wherein in step (7) of the above process, the amount of Zr introduced is reduced, and the Zr content of the functional layer of the resulting film is 2.2 at.%.

[0075] Comparative Example 3

[0076] A method for preparing a Zr-DLC gradient composite film, wherein in step (7) of the above process, the Zr introduction amount is increased, and the Zr content of the functional layer of the resulting film is 5.2 at.%.

[0077] The composite films prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to tribological performance tests in various environments, as detailed below:

[0078] The aforementioned thin films were evaluated using a ball-disc friction and wear tester. The grinding balls were 8mm diameter AISI 440C stainless steel balls, and the test load was 1N. Three different testing environments were used:

[0079] Deionized water environment (water-based liquid medium): The test area is immersed in deionized water;

[0080] Diesel lubrication environment (oil-based liquid lubricating medium): The test area was immersed in 0# commercial diesel fuel;

[0081] Simulated lunar dust abrasive environment (solid particle abrasive media): Simulated lunar dust particles with a particle size of 10~25μm are uniformly laid on the surface of the thin film.

[0082] The test results are shown in Table 1 below.

[0083] Table 1. Comparison of the multi-environmental tribological properties of the thin films prepared in Examples 1-3 and Comparative Examples 1-3

[0084]

[0085] In the table, N / A indicates that the specific value cannot be calculated due to film wear-through failure.

[0086] As shown in Table 1, compared with pure DLC (Comparative Example 1) and Comparative Examples 2 and 3 (which have Zr contents below and above the Zr content range of this invention), Examples 1-3, with Zr contents within the limits defined by this invention, maintained stable tribological behavior under three environments: deionized water, diesel lubrication, and simulated lunar dust. They also exhibited varying degrees of performance improvement in different environments. Samples with different Zr contents showed certain differential characteristics under different environments: Example 1 had the lowest coefficient of friction under deionized water conditions; Example 2 exhibited both the lowest coefficient of friction and the lowest wear rate under diesel lubrication conditions, and also had the lowest wear rate under deionized water conditions; Example 3 had the lowest wear rate under simulated lunar dust conditions. This indicates that appropriate Zr doping can improve the tribological performance of DLC films under different tribological environments.

[0087] In Comparative Example 3, when the Zr content increased to 5.2 at.%, the friction coefficient and wear rate under deionized water, diesel lubrication, and simulated lunar dust environments were significantly higher than those in the examples within the range of 2.6–4.7 at.%, indicating that excessive Zr introduction is detrimental to the stability of the film's frictional properties. Therefore, this invention does not achieve performance improvement by simply increasing the Zr doping content, but rather utilizes the regulatory effect of Zr on the amorphous carbon network within a specific Zr content range to improve the frictional adaptability of the DLC film in different complex environments. When the Zr content is controlled within the range of 2.6–4.7 at.%, Zr can participate in the regulation of the carbon network structure, forming a stable Zr-C bond structure, enhancing the stability of the amorphous carbon network, and enabling the film to maintain good frictional stability in different environments such as deionized water, diesel lubrication, and simulated lunar dust. When the Zr content is further increased to 5.2 at.%, the excessive Zr introduction leads to an imbalance in the regulation of the carbon network structure, resulting in a significant decrease in the multi-environment frictional properties of the film.

[0088] To further analyze the form in which Zr exists in DLC films, XPS analysis was performed on a representative 4.7 at.% Zr-modified DLC film. Figure 2 As shown, the Zr3d peak fitting results indicate the presence of a clear Zr-C chemical bond state in the film, demonstrating that Zr can chemically bond with the carbon matrix. The introduction of an appropriate amount of Zr helps stabilize the carbon network structure and improves the film's load-bearing capacity and tribological stability. Further analysis of the microstructure of the 4.7 at.% Zr-modified DLC film was conducted using TEM. Figure 3As shown, the film maintains typical amorphous structural characteristics, with no obvious coarse grains or large-sized second-phase particles observed. This indicates that the film at this Zr content is still dominated by an amorphous carbon structure, and Zr can participate in the regulation of the amorphous carbon network without forming a significant large-sized crystalline second phase. Combined with XPS analysis results, it can be seen that Zr mainly enhances the stability of the carbon network through the Zr-C bonding structure, thereby improving the overall tribological properties of the film.

[0089] Furthermore, the wear morphology of pure DLC and 4.7 at.% Zr modified DLC films under simulated lunar dust environment was compared (e.g.) Figure 4 As shown in the figure, the wear tracks of pure DLC films exhibit obvious ploughing grooves, while the wear tracks of Zr-modified DLC films are smoother and show no obvious penetrating damage. This indicates that the introduction of Zr can effectively improve the film's resistance to cutting and ploughing by hard particles. In contrast, when the Zr content increases to 5.2 at.%, the tribological properties of the film decrease significantly, indicating that excessive Zr introduction may lead to an imbalance in the carbon network structure, thereby affecting the film's structural integrity and tribological stability. Therefore, rationally controlling the Zr doping content is key to achieving DLC ​​film structural optimization and multi-environment tribological adaptability.

[0090] This invention prepares a Zr-modified diamond-like carbon film with good adaptability to various environmental frictions by controlling the Zr doping content within the range of 2.6 to 4.7 at.% and combining it with a gradient multilayer structure design. This allows the film to adapt to different types of friction environments such as deionized water, diesel lubrication, and simulated lunar dust, providing a feasible thin film material solution for wear-resistant protection of key moving parts under complex service conditions.

Claims

1. A Zr-DLC gradient composite film with multi-environmental friction adaptability, characterized in that, The Zr-DLC gradient composite film is deposited on the surface of the substrate; the Zr-DLC gradient composite film includes, from the substrate outward, a Ti bonding layer (1), a TiN transition layer (2), an undoped DLC buffer layer (3) and a Zr modified DLC functional layer (4). In the Zr-modified DLC functional layer (4), the atomic percentage of Zr element is 2.6 at.%~4.7 at.%, and Zr element is distributed in the amorphous carbon network in the form of Zr-C chemical bonding.

2. The Zr-DLC gradient composite film with multi-environmental friction adaptability according to claim 1, characterized in that, In the Zr-modified DLC functional layer (4), Zr elements are dispersed at the atomic level and the stability of the amorphous carbon network is regulated by the Zr-C bonding structure. The film exhibits a single amorphous phase structure under a transmission electron microscope, with no obvious nanocrystals or second phase particles precipitated.

3. The Zr-DLC gradient composite film with multi-environmental friction adaptability according to claim 1, characterized in that, The Zr-modified DLC functional layer (4) exhibits a friction coefficient ≤0.19 and a wear rate ≤1.35×10⁻⁶ in deionized water, diesel lubrication, and simulated lunar dust abrasive environments. -5 mm 3 / (N·m).

4. The Zr-DLC gradient composite film with multi-environmental friction adaptability according to claim 1, characterized in that, The thickness of the Ti bonding layer (1) is 50~100nm, the thickness of the TiN transition layer (2) is 100~300nm, the thickness of the undoped DLC buffer layer (3) is 100~500nm, and the thickness of the Zr modified DLC functional layer (4) is 1.0~3.0μm.

5. A method for preparing a Zr-DLC gradient composite thin film with multi-environmental tribological adaptability as described in any one of claims 1 to 4, characterized in that, The steps are as follows: S1: After cleaning and drying the substrate, it is clamped onto the rotating base frame of the coating chamber; S2: Evacuate the coating chamber until the background vacuum level is below 5.0 × 10⁻⁶. -3 Pa, and heated to the deposition temperature; S3: Introduce argon gas, turn on the carbon target, titanium target and C-Zr splicing target respectively for pre-sputtering, and then turn them off; Introduce argon gas again, turn on the ion source and apply bias voltage to perform ion etching and cleaning on the substrate; S4: Introduce argon gas, turn on the titanium target, and sputter to deposit a Ti bonding layer on the substrate surface (1). S5: Introduce argon and nitrogen gas, keep the titanium target open, and perform reaction sputtering to deposit a TiN transition layer (2) on the Ti bonding layer (1). S6: Introduce argon and acetylene, turn on the carbon target, and deposit an undoped DLC buffer layer (3) on the TiN transition layer (2). S7: Introduce argon and acetylene, turn on the C-Zr splicing target, and deposit a Zr-modified DLC functional layer (4) with a Zr atomic percentage of 2.6 at.%~4.7 at.% on the DLC buffer layer (3) by adjusting the spatial position of the base frame in the deposition chamber. S8: After deposition, turn off the power and gas supply, and remove the sample after cooling to the specified temperature.

6. The method for preparing Zr-DLC gradient composite thin films with multi-environmental tribological adaptability according to claim 5, characterized in that, In step S3, the revolution speed of the rotating base is adjusted to 3~5 rpm, the rotation speed is adjusted to 2~5 rpm, the ion source voltage is adjusted to 500~1200V, the substrate bias voltage is adjusted to -1000V, and the etching and cleaning time is adjusted to 10~20min.

7. The method for preparing a Zr-DLC gradient composite thin film with multi-environmental tribological adaptability according to claim 5, characterized in that, In S4, the deposition conditions of the Ti bonding layer (1) are: gas pressure 0.5~0.8Pa, titanium target sputtering power 400~600W, substrate bias voltage -80~-120V, and deposition time 10~30min.

8. The method for preparing Zr-DLC gradient composite thin films with multi-environmental friction adaptability according to claim 5, characterized in that, In S5, the deposition time of the TiN transition layer (2) is 60-120 min; in S6, the deposition time of the undoped DLC buffer layer (3) is 20-40 min.

9. The method for preparing a Zr-DLC gradient composite thin film with multi-environmental friction adaptability according to claim 5, characterized in that, In S7, the C-Zr splicing target is composed of carbon target and zirconium target splicing. The arrangement of the zirconium target makes a continuous gradient of zirconium / carbon ion beam flux along the length of the target. The deposition conditions of the Zr modified DLC functional layer (4) are: gas pressure 0.6~0.7Pa, substrate bias voltage -100V, C-Zr splicing target splicing power 800~1000W, and deposition time 120~200min.

10. The application of the Zr-DLC gradient composite film with multi-environment friction adaptability as described in any one of claims 1 to 4 in wear-resistant protection of surfaces of aerospace equipment, precision transmission components or complex environmental friction pairs.

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