Design method of multilayer composite DLC thin film structure

Abstract

This invention discloses a design method for multilayer composite DLC thin film structures, comprising: constructing a sublayer DLC composite thin film model; optimizing the sublayer DLC composite thin film model to obtain a sublayer DLC composite thin film; performing performance tests on the sublayer DLC composite thin film to obtain its mechanical properties; analyzing the mechanical properties of the sublayer DLC composite thin film; based on the analysis results, compositing multiple sublayer DLC composite thin films according to a preset number of layers, layer thickness, and interlayer interface modulation ratio to form a multilayer composite DLC thin film; performing macroscopic performance calculations on the multilayer composite DLC thin film; determining whether the multilayer composite DLC thin film meets the requirements based on the macroscopic performance; if not, returning to the previous step. This solves the problem in existing technologies where it is difficult to reveal the physicochemical change mechanisms occurring during the thin film structure process.

Description

Technical Field

[0001] This invention belongs to the technical field of thin film design methods, and relates to a design method for multilayer composite DLC thin film structures. Background Technology

[0002] DLC (Diamond-Like Carbon) is an amorphous carbon material similar to diamond, possessing excellent hardness, wear resistance, and corrosion resistance. It can improve the surface hardness and wear resistance of substrate materials and is widely used in surface coatings and tribology. Multilayer DLC films are materials composed of multiple alternating stacked sublayer carbon-based films. The dopant content and carbon content of each DLC layer, as well as the number of layers, layer thickness, and interlayer interface modulation ratio, can be adjusted according to requirements. Generally, multilayer DLC films have better wear resistance and chemical stability than single-layer DLC films because the multilayer structure provides more protective layers; different tribological properties can be formed between different layers, thereby controlling friction and wear; and stress can be effectively controlled, reducing stress concentration and the risk of cracking, thus achieving comprehensive optimization of film performance. Multilayer DLC films offer more advantages than single-layer DLC films, thus their application range is wider.

[0003] The mutual development of numerical simulation technology and computer hardware and software provides more accurate and efficient simulation methods for scientific research and engineering practice in various fields.

[0004] Currently, common numerical simulation methods for thin film design include the finite difference method, the finite element method, and the boundary element method. These methods, due to the trade-off between model accuracy and computational efficiency, require the selection of appropriate discretization methods and the setting of numerous suitable parameters, placing high demands on computational resources. In particular, the accuracy and calculation results of the finite difference method are related to the mesh size; smaller mesh sizes can provide higher accuracy but also increase computation time. Furthermore, it is suitable for simple geometries and boundary conditions, and may require further extension and improvement for complex multilayer thin film structures. The finite element method is more difficult to model, requiring accurate simulation of the geometry, material properties, and boundary conditions of multilayer thin films. It demands a large amount of experimental data, professional knowledge, and reasonable mesh generation and convergence analysis. The boundary element method cannot accurately simulate the properties of non-uniform thin films, generally assuming that the films are homogeneous. In addition, these methods typically only simulate specific physical processes and struggle to comprehensively consider the influence of multiple factors. Moreover, these computational methods are relatively macroscopic, generally at the micrometer level, making it difficult to reveal the mechanisms of change occurring in the physicochemical processes of thin film structures. Summary of the Invention

[0005] The purpose of this invention is to provide a design method for multilayer composite DLC thin film structures, which solves the problem in the prior art that it is difficult to reveal the change mechanism that occurs in the physicochemical process of the thin film structure.

[0006] The technical solution adopted in this invention is a design method for a multilayer composite DLC thin film structure, comprising the following steps:

[0007] Step 1: Construct a sublayer DLC composite film model, optimize the sublayer DLC composite film model, and obtain the sublayer DLC composite film.

[0008] Step 2: Perform performance tests on the sublayer DLC composite film to obtain its mechanical properties;

[0009] Step 3: Analyze the mechanical properties of the sublayer DLC composite film;

[0010] Step 4: Based on the analysis results of Step 3, multiple sub-layer DLC composite films are composited according to the preset number of layers, layer thickness, and interlayer interface modulation ratio to form a multilayer composite DLC film.

[0011] Step 5: Perform macroscopic performance calculations on the multilayer composite DLC film. Determine whether the multilayer composite DLC film meets the requirements based on the macroscopic performance. If not, return to step 4.

[0012] The invention is further characterized in that,

[0013] The process of constructing the sublayer DLC composite thin film model in step 1 is as follows:

[0014] First, the primitive cells of the pure DLC thin film model are constructed using first-principles software, and the primitive cells are initially expanded. Then, elemental atoms or compounds are doped to form a DLC composite thin film model. Finally, the DLC composite thin film model is expanded to obtain a sublayer DLC composite thin film model.

[0015] The optimization process in step 1 is as follows: first, the atoms in the sublayer DLC composite film model system are initialized, relaxed, and heated and quenched to obtain the sublayer DLC composite film.

[0016] Step 2 involves sequentially performing nano-indentation, nano-scratching, and nano-stretching treatments on the sublayer DLC composite film to obtain indentation, scratch, and stretching data. The data is then processed to obtain the mechanical and tribological properties of the sublayer DLC composite film.

[0017] The mechanical and tribological properties of the sublayer DLC composite film in step 2 include: hardness, elastic modulus, coefficient of friction, wear rate, bonding strength, and internal stress.

[0018] Step 3 specifically involves: importing the sublayer DLC composite film into OVITO software; analyzing its radial distribution function using the Coordination analysis module to obtain the internal structure of the sublayer DLC composite film; analyzing and statistically analyzing its cluster distribution and bond hybridization using the Cluster analysis module to obtain the changes in its mechanical and tribological properties; extracting the coordinates of the atomic layers on the surface of the sublayer DLC composite film using the Constructsurface mesh module, calculating the roughness of the DLC film, and thus obtaining the principle of the changes in tribological properties.

[0019] The macroscopic performance calculation process in step 5 is as follows: the multilayer composite DLC film is imported into the finite element software Ansys, and the mechanical and tribological property data of the sublayer DLC composite film obtained in step 2 are used as the simulation parameters of the interlayer and interior of the film in the finite element software Ansys. Mesh generation and boundary condition parameter settings are performed, and the macroscopic performance of the multilayer composite DLC film is calculated through the workbench module.

[0020] The beneficial effects of this invention are as follows: The design method for multilayer composite DLC thin film structures of this invention uses the mechanical property test results of the sublayer DLC composite thin film as simulation parameters of finite element software, solving the problems of requiring a large amount of experimental data and professional knowledge, as well as reasonable mesh generation and convergence analysis for finite element method models; firstly, a sublayer thin film model is established through first-principles calculations, and then various physical processes of the DLC composite thin film are simulated to achieve performance testing and microstructure analysis, studying the intrinsic mechanism from a scale that cannot be reached by experiments; based on the analysis results, sublayer thin films are selected for multilayer composite, realizing the alternation of sublayers with different properties. By combining these technologies, we can achieve coordinated control of mechanical and tribological properties to obtain films that meet the requirements. Simulating a series of physicochemical processes such as the formation, friction, and wear of DLC films can reveal the formation mechanism and tribological properties of DLC composite films, providing guidance for the design and application of films or coatings. Cross-scale numerical simulation technology can predict the properties and behavior of sublayer and multilayer composite DLC film structures, thereby reducing the time and cost of experimental testing and improving research efficiency. By selecting the interlayer stress matching of different materials, stress equilibrium and stress relief of films can be achieved, reducing the risk of stress concentration and cracking. Attached Figure Description

[0021] Figure 1 This is a model diagram of a sublayer B-DLC composite film obtained by the design method of the multilayer composite DLC film structure of the present invention;

[0022] Figure 2 This is a radial distribution function diagram of the sublayer B-DLC composite film obtained by the design method of the multilayer composite DLC film structure of the present invention;

[0023] Figure 3 This is a hybridization state distribution diagram of the sublayer B-DLC composite film obtained by the design method of the multilayer composite DLC film structure of the present invention;

[0024] Figure 4 This is a comparison and verification diagram of the mechanical properties of the sublayer MoS2-DLC composite film model obtained by the design method of the multilayer composite DLC film structure of this invention;

[0025] Figure 5 This is the wear atomic profile diagram of the sublayer MoS2-DLC composite thin film model obtained by the design method of the multilayer composite DLC thin film structure of the present invention.

[0026] Figure 6 This is a comparison and verification diagram of the tribological properties of the sublayer B4C-DLC composite film model obtained by the design method of the multilayer composite DLC film structure of this invention.

[0027] Figure 7 This is a design model diagram of a multilayer B4C / WC / DLC and B4C / MoS2 / DLC composite thin film structure obtained by the design method of the multilayer composite DLC thin film structure of the present invention;

[0028] Figure 8 The stress-strain contour plot is obtained by simulating the B4C / WC / DLC / B4C / MoS2 / DLC composite thin film model obtained by the design method of the multilayer composite DLC thin film structure of the present invention using Ansys Workbench. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0030] The design method for multilayer composite DLC thin film structures includes the following steps:

[0031] Step 1: Construct a sublayer DLC composite film model, optimize the sublayer DLC composite film model, and obtain the sublayer DLC composite film.

[0032] Specifically, the process begins by constructing the unit cell of a pure DLC thin film model using first-principles software (Material Studio). The unit cell is then expanded based on the dopant content. Next, one or more elemental atoms or compounds are doped to form a DLC composite thin film model. Finally, the DLC composite thin film model is expanded to obtain a sublayer DLC composite thin film model. The sublayer DLC composite thin film model is exported as a CIF file, and OVITO software is used to convert the file type to a LAMMPS-recognizable data file. An optimization program is then written, which involves: first, initializing and relaxing the atoms in the sublayer DLC composite thin film model system to minimize its energy and ensure the system's structural stability; then, heating and quenching the atoms in the sublayer DLC composite thin film model system to obtain the sublayer DLC composite thin film.

[0033] Step 2: Perform performance tests on the sublayer DLC composite film to obtain its mechanical (mechanical and tribological) properties.

[0034] Specifically, the sublayer DLC composite film is subjected to nanoindentation, nano-scratching, and nano-stretching treatments sequentially using the LAMMPS programming language to obtain indentation, scratch, and stretching data. These data are then processed using specific formulas to obtain the mechanical and tribological properties of the sublayer DLC composite film. These properties include: hardness, elastic modulus, coefficient of friction, wear rate, bonding strength, and internal stress.

[0035] Step 3: Perform mechanical property analysis based on the sublayer DLC composite film;

[0036] The sublayer DLC composite film was imported into OVITO software. Its radial distribution function was analyzed using the Coordination analysis module to obtain the internal structure of the sublayer DLC composite film. Its cluster distribution and bond hybridization (changes in carbon valence state) were analyzed and statistically analyzed using the Cluster analysis module to reveal the changes in the mechanical and tribological properties of the DLC film. The coordinates of the atomic layers on the surface of the sublayer DLC composite film were extracted using the Construct surface mesh module to calculate the roughness of the DLC film, thereby obtaining the principle of the changes in tribological properties.

[0037] Step 4: Based on the analysis results of Step 3, multiple sub-layer DLC composite films are composited according to the preset number of layers, layer thickness, and interlayer interface modulation ratio to form a multilayer composite DLC film.

[0038] Specifically, multiple sublayer DLC composite films are selected based on macroscopic properties and composited according to preset layers, layer thicknesses, and interlayer interface modulation ratios to obtain multilayer composite DLC films with alternating soft and hard properties, complementary performance, and good bonding strength. The multilayer DLC composite film model can be constructed using the 3D modeling software SolidWorks and saved as an .xt file.

[0039] Step 5: Perform macroscopic performance calculations on the multilayer composite DLC film. Determine whether the multilayer composite DLC film meets the requirements based on the macroscopic performance. If not, return to step 4.

[0040] Specifically, the multilayer composite DLC film is imported into the finite element software Ansys, and the mechanical and tribological property data of the sublayer DLC composite film obtained in step 2 are used as the simulation parameters of the interlayer and interior of the film in the finite element software Ansys. Mesh generation and boundary condition parameter settings are performed, and the macroscopic properties of the multilayer composite DLC film are calculated through the Workbench module. Based on the macroscopic properties, it is determined whether the multilayer composite DLC film meets the requirements. If not, return to step 4 and reselect the sublayer DLC composite film for composite.

[0041] Through the above methods, the design method for multilayer composite DLC thin film structures of this invention combines molecular dynamics, first-principles calculations, and finite element analysis, enabling precise simulation at the atomic level, including information such as atomic position, velocity, and energy. This allows for in-depth understanding of the microstructure and properties of DLC thin films and enables the study of intrinsic mechanisms at scales inaccessible to experiments. Simulating a series of physicochemical processes such as the formation, friction, and wear of DLC thin films reveals the formation mechanism and tribological properties of DLC composite thin films, providing guidance for the design and application of thin films or coatings. Furthermore, it enables efficient calculation and prediction of thin films, utilizing cross-scale numerical simulation technology. This technology can predict the properties and behaviors of sublayer and multilayer composite DLC thin film structures, such as mechanical and tribological properties, thereby reducing experimental testing time and costs and improving research efficiency. It can achieve the alternating combination of sublayers with different properties, thus enabling coordinated control of mechanical and tribological properties. For example, in a structure with alternating hard and soft layers, the hard layer can provide higher hardness and wear resistance, while the soft layer can provide a lower coefficient of friction and better lubricity. It can effectively control the stress of the film, reducing the risk of stress concentration and cracking. By selecting the interlayer stress matching of different materials, stress balance and stress relief of the film can be achieved.

[0042] Example 1

[0043] Step 1: Specifically, firstly, the unit cell of the pure DLC thin film model is constructed using first-principles software (Material Studio). The cell is initially expanded based on the dopant content and the desired expansion factor. Then, boron (B) atoms are doped to form a B-DLC composite thin film model. Finally, the B-DLC composite thin film model is expanded to obtain a sublayer B-DLC composite thin film model. The sublayer B-DLC composite thin film model is exported as a CIF file. Using OVITO software, the file type is converted to a LAMMPS-recognizable data file. An optimization program is then written. Specifically, the optimization program first initializes and relaxes the atoms in the sublayer B-DLC composite thin film model system to minimize the energy and stabilize the system structure. Then, the atoms in the sublayer B-DLC composite thin film model system are heated and quenched to obtain the sublayer B-DLC composite thin film. (See...) Figure 1 .

[0044] Step 2: The sublayer B-DLC composite film is subjected to nanoindentation, nano-scratching, and nano-stretching treatments sequentially using the LAMMPS programming language to obtain indentation, scratch, and stretching data. The data is then processed using specific formulas to obtain the mechanical and tribological properties of the sublayer B-DLC composite film, including: hardness, elastic modulus, coefficient of friction, wear rate, bonding strength, and internal stress.

[0045] Step 3: Import the sublayer B-DLC composite film and its mechanical properties into OVITO software, and analyze its radial distribution function using the Coordination analysis module. (See...) Figure 2 The internal structural changes of the sublayer B-DLC composite film were obtained. Figure 2 It can be seen that with the doping of B atoms, the first peak of the radial distribution function of the B-DLC composite film shifts to the left relative to 1.42 Å of the pure DLC film, indicating that the carbon-based film network structure has changed and some C / C bonds have broken. Furthermore, with continued B doping, the second peak of the B-DLC composite film shifts significantly to the left relative to 2.52 Å of the pure DLC film, indicating that both the C / C bond lengths and bond angles in the carbon-based network structure have been distorted. Therefore, it can be concluded that B doping alters the bonding direction of the DLC film structure. The cluster distribution and carbon valence states were analyzed and statistically analyzed using the Cluster analysis module. Figure 3 .from Figure 3 As can be seen from this, with the doping of B atoms, sp 3 The initial slight decrease, followed by an increase and then a decrease indicates that boron doping caused the mechanical properties of the thin film to undergo a process of first decreasing, then increasing, and then decreasing again; sp 2The initial slight increase followed by a decrease and then another increase indicates that graphitization occurred in the first and third doping stages of the B-DLC composite film, leading to an increase in the tribological properties of the film system. However, no graphitization occurred in the second doping stage, resulting in a decrease in the tribological properties of the B-DLC composite film. The coordinates of the atomic layers on the surface of the sublayer B-DLC composite film were extracted using the Construct surface mesh module, and the wear rate was calculated using the wear rate calculation formula to obtain the roughness of the sublayer B-DLC film.

[0046] Example 2

[0047] Step 1: Specifically, firstly, the unit cell of the pure DLC thin film model is constructed using first-principles software (Material Studio). The unit cell is then initially expanded based on the dopant content. Next, MoS2 compound doping is performed to form a MOS2-DLC composite thin film model. Finally, the MOS2-DLC composite thin film model is expanded to obtain sublayer MOS2-DLC composite thin film models with different MoS2 contents. The sublayer MOS2-DLC composite thin film model is exported as a CIF file. Using OVITO software, the file type is converted to a LAMMPS-recognizable data file. An optimization program is then written. Specifically, the optimization program first initializes and relaxes the atoms in the sublayer MOS2-DLC composite thin film model system to minimize the energy of the system and maximize its structural stability. Then, the atoms in the sublayer MOS2-DLC composite thin film model system are heated and quenched to obtain the sublayer MOS2-DLC composite thin film.

[0048] Step 2: Using the LAMMPS programming language, the sublayer MOS2-DLC composite film is sequentially subjected to nanoindentation, nano-scratching, and nano-stretching treatments to obtain indentation, scratch, and stretching data. These data are then processed using specific formulas to obtain the mechanical and tribological properties of the sublayer MOS2-DLC composite film. (See...) Figure 4 . Figure 4 (a) shows the hardness and elastic modulus of the MoS2-DLC composite film formed by doping MoS2 in the experiment. As can be seen from the figure, the hardness and elastic modulus of the sublayer MOS2-DLC composite film continue to decrease with the increase of the content of the doping compound MoS2. Figure 4Figure (b) shows the hardness and elastic modulus of the doped MoS2-DLC composite film calculated using the numerical simulation method. As can be seen from the figure, the hardness and elastic modulus of the MOS2-DLC composite film continuously decrease with the increase of the MoS2 doping content. From the comparison of the two figures, it can be seen that the simulation results of the MOS2-DLC composite film calculated using the simulation method of this invention are in good agreement with the experimental results. This shows that it is feasible to use the numerical simulation method of this invention to study thin film design.

[0049] Step 3: Import the sublayer MOS2-DLC composite film into OVITO software. Analyze its radial distribution function using the Coordination analysis module to obtain the internal structure of the sublayer MOS2-DLC composite film. Analyze and statistically analyze its cluster distribution and carbon valence states using the Cluster analysis module. Extract the coordinates of the atomic layers on the surface of the sublayer MOS2-DLC composite film using the Construct surface mesh module, such as... Figure 5 As shown, the wear rate was calculated using the wear rate calculation formula to obtain the roughness of the sublayer MOS2-DLC film.

[0050] Example 3

[0051] Step 1: Specifically, firstly, the unit cell of the pure DLC thin film model is constructed using first-principles software (Material Studio). The unit cell is then initially expanded based on the dopant content. Next, B4C compound doping is performed to form a B4C-DLC composite thin film model. Finally, the B4C-DLC composite thin film model is expanded to obtain sublayer B4C-DLC composite thin film models with different B4C contents. The sublayer B4C-DLC composite thin film model is exported as a CIF file. Using OVITO software, the file type is converted to a LAMMPS-recognizable data file. An optimization program is then written. Specifically, the optimization program first initializes and relaxes the atoms in the sublayer B4C-DLC composite thin film model system to minimize the energy of the system and maximize its structural stability. Then, the atoms in the sublayer B4C-DLC composite thin film model system are heated and quenched to obtain the sublayer B4C-DLC composite thin film.

[0052] Step 2: Using the LAMMPS programming language, the B4C-DLC composite film of the sublayer is sequentially subjected to nanoindentation, nanoscraping, and nanostretching treatments to obtain indentation, scratch, and stretching data. These data are then processed using specific formulas to obtain the mechanical and tribological properties of the B4C-DLC composite film, such as... Figure 6 As shown, Figure 6(a) shows the hardness and elastic modulus of the B4C-DLC composite film formed by B4C doping in the experiment. As can be seen from the figure, the hardness and elastic modulus of the B4C-DLC composite film increase and then decrease with the increase of B4C dopant content. Figure 6 (b) shows the hardness and elastic modulus of the B4C-DLC composite film formed by B4C doping using the numerical simulation method. As can be seen from the figure, with the increase of B4C dopant content, the hardness and elastic modulus of the B4C-DLC composite film calculated by the simulation method of this invention first increase and then decrease. From the two comparison figures, it can be seen that the simulation results of the hardness and elastic modulus of the MOS2-DLC composite film calculated by the simulation method of this invention are in good agreement with the experimental results. This shows that it is feasible to use the numerical simulation method of this invention to study thin film design.

[0053] Step 3: Import the sublayer B4C-DLC composite film into OVITO software. Analyze its radial distribution function using the Coordination analysis module to obtain the internal structure of the sublayer B4C-DLC composite film. Analyze and statistically analyze its cluster distribution and carbon valence state using the Cluster analysis module. Extract the coordinates of the atomic layers on the surface of the sublayer B4C-DLC composite film using the Construct surface mesh module, and calculate the wear rate using the wear rate calculation formula to obtain the roughness of the sublayer B4C-DLC film.

[0054] Example 4

[0055] Step 1: From the various types of sublayer composite DLC structure films obtained according to Examples 1-3, select sublayer DLC composite films with high hardness, low friction coefficient, good wear resistance, and good bonding strength, such as sublayer co-doped B4C / MoS2 / DLC composite films and sublayer co-doped B4C / WC / DLC composite films. Figure 7 As shown, gradient composite is performed according to the preset number of layers, layer thickness, and interlayer interface modulation ratio. That is, the sublayer co-B4C / MoS2 / DLC composite film is combined with the sublayer co-B4C / WC / DLC composite film to obtain a multilayer composite film with alternating soft and hard properties, complementary performance, and good bonding strength. The model of the multilayer B4C / WC / DLC / B4C / MoS2 / DLC composite film is reconstructed using the 3D modeling software SolidWorks and saved as an .xt file.

[0056] Step 2: Import the B4C / WC / DLC / B4C / MoS2 / DLC composite film model obtained in Step 1 into the finite element software Ansys. Simultaneously, use the hardness, elastic modulus, and bonding strength data obtained from the performance calculations of the B4C / MoS2 / DLC and B4C / WC / DLC composite films as some of the simulation parameters in Ansys to set the interlayer parameters. Then, mesh the B4C / WC / DLC / B4C / MoS2 / DLC composite film model, apply boundary conditions, and use the Workbench module to calculate and study the macroscopic properties of the multilayer DLC composite film. Refer to the performance data of the B4C / WC / DLC / B4C / MoS2 / DLC composite film calculated by the finite element software Ansys for analysis, such as... Figure 8 The image shows the stress-strain contour plot of the B4C / WC / DLC / B4C / MoS2 / DLC composite film. The stress-strain characteristics of the multilayer film can be obtained through indentation, leading to further information on its mechanical properties. Using this film research method, the optimal gradient design scheme can be selected according to process requirements and industrial needs to obtain the desired high-hardness, wear-resistant multilayer B4C / WC / DLC / B4C / MoS2 / DLC composite film.

Claims

1. A method of designing a multilayer composite DLC thin film structure, characterized in that, The method comprises the following steps: Step 1, constructing a sub-layer DLC composite film model, optimizing the sub-layer DLC composite film model, and obtaining a sub-layer DLC composite film; Step 2, testing the performance of the sub-layer DLC composite film to obtain its mechanical properties; Step 3, analyzing the mechanical properties of the sub-layer DLC composite film; Step 4, according to the analysis result of step 3, a plurality of sub-layer DLC composite films are compounded according to a preset number of layers, layer thickness and interlayer interface modulation ratio to form a multilayer composite DLC film; Step 5, calculating the macroscopic performance of the multilayer composite DLC film, and judging whether the multilayer composite DLC film meets the requirements according to the macroscopic performance, and if not, returning to step 4. The process of constructing the sub-layer DLC composite film model in step 1 is as follows: First, a first-principle software is used to construct a unit cell of a pure DLC film model, and the unit cell is preliminarily expanded; then a single atom or a compound is doped to form a DLC composite film model; finally, the DLC composite film model is expanded to obtain a sub-layer DLC composite film model; wherein the single atom is a B atom, and the compound is MoS2, B4C or WC; The optimization process in step 1 is as follows: first, the atoms in the sub-layer DLC composite film model system are initialized, relaxed, heated and quenched to obtain a sub-layer DLC composite film.

2. The method of designing a multilayered composite DLC thin film structure according to claim 1, wherein The process of step 2 is as follows: the sub-layer DLC composite film is sequentially subjected to nanoindentation, nanoscratch and nanotension treatment to obtain indentation, scratch and tension data, and the data is processed to obtain the mechanical and tribological properties of the sub-layer DLC composite film.

3. The method of designing a multilayer composite DLC thin film structure according to claim 1 or 2, wherein The mechanical and tribological properties of the sub-layer DLC composite film in step 2 include hardness, elastic modulus, friction coefficient, wear rate, bonding strength and internal stress.

4. The method of designing a multilayered composite DLC thin film structure according to claim 1, wherein Step 3 specifically is: introducing the sub-layer DLC composite film into OVITO software, analyzing its radial distribution function through Coordination analysis module to obtain the internal structure of the sub-layer DLC composite film; analyzing and counting the cluster distribution and bond hybridization state through Cluster analysis module to obtain the changes of mechanical and tribological properties; extracting the coordinates of the surface atomic layer of the sub-layer DLC composite film through Construct surface mesh module to calculate the roughness of the DLC film and further obtain the principle of the change of tribological properties.

5. The method of designing a multilayer composite DLC thin film structure according to claim 1, wherein, The macroscopic performance calculation process in step 5 is as follows: introducing the multilayer composite DLC film into the finite element software Ansys, and taking the mechanical and tribological property data of the sub-layer DLC composite film obtained in step 2 as the interlayer and internal simulation parameters of the film in the finite element software Ansys, performing grid division and boundary condition parameter setting, and calculating the macroscopic performance of the multilayer composite DLC film through the workbench module.

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