Low-silicon-doped hydrogenated amorphous carbon composite coating based on staged bonding regulation and dual-path self-adaption as well as preparation and application of low-silicon-doped hydrogenated amorphous carbon composite coating

Abstract

The invention relates to a low-silicon-doped hydrogenated amorphous carbon composite coating based on staged bonding regulation and dual-path self-adaption as well as preparation and application thereof, and belongs to the technical field of surface engineering. According to the coating, accurate regulation and control of a microstructure are achieved through low-concentration silicon doping, and silicon atoms follow the staged bonding evolution law of breaking an sp3 network firstly and then promoting sp2 ordering, so that the coating forms a transition state structure with moderate toughness (H3 / E2 is 0.23-0.31 GPa) and remarkable graphitization potential. In the reciprocating sliding friction process, the coating can trigger double-path self-adaptive behaviors at the same time; a high-quality graphene lubricating transfer film is generated on an interface in situ to reduce the friction coefficient; friction-induced work hardening occurs on the subsurface layer to improve the bearing capacity and wear resistance. The preparation method of the coating is realized through a plasma enhanced chemical vapor deposition process, and the key point is that the flow of silane gas is accurately controlled in a narrow window of 5-20 sccm (preferably 10 sccm). The coating is particularly suitable for a dry or atmospheric environment reciprocating sliding part with the working frequency of 1-5 Hz and the load of 2-15 N, and the technical problem that low friction and low abrasion of a traditional diamond-like carbon coating are difficult to achieve at the same time is solved.

Description

Technical Field

[0001] This invention belongs to the field of advanced surface engineering and tribology, specifically relating to a diamond-like carbon-based composite coating with intelligent tribological response characteristics. More specifically, this invention relates to a hydrogenated amorphous carbon (aC:H) composite coating that achieves dual-path adaptive "interface lubrication" and "subsurface strengthening" in reciprocating sliding under varying operating conditions through low-concentration silicon doping and precise staged control of its bonding behavior. Furthermore, this invention relates to the preparation method of this coating and its application in key friction pair components of high-end equipment. Background Technology

[0002] Diamond-like carbon (aC):H coatings exhibit great application potential in key friction pairs in machinery, automotive, and aerospace fields due to their excellent hardness, low coefficient of friction, and good chemical inertness. Among them, hydrogenated amorphous carbon coatings have attracted considerable attention due to their relatively mild preparation process and low internal stress. However, traditional aC:H coatings suffer from a common inherent contradiction in their tribological properties, namely the "trade-off effect": high sp... 3 Carbon content contributes to high hardness and wear resistance, but often comes with high internal stress and brittleness, making it prone to spalling failure under cyclic loading; while high sp... 2 While a high carbon content can help form a lubrication transfer film to reduce friction, it can also lead to an overly soft coating, reduced load-bearing capacity, and a sharp increase in wear rate. Therefore, achieving both stable ultra-low friction and ultra-high wear resistance in coatings under a wide range of operating conditions has long been a technical bottleneck that has troubled those skilled in the art.

[0003] To improve the overall performance of aC:H coatings, elemental doping (such as Si, F, N, Me, etc.) is a common strategy. Silicon doping is considered effective in releasing internal stress, improving thermal stability, and enhancing the adhesion between the coating and the substrate. However, current mainstream understanding of the mechanism of silicon doping is largely based on the "random substitution" or "homogeneous composite" model, where silicon atoms are considered to randomly enter the carbon network, and their bonding behavior is considered static and homogeneous. Doped coatings prepared based on this understanding often exhibit limited and unpredictable performance improvements, failing to fundamentally reconcile the contradiction between "low friction" and "low wear." Especially under dynamic reciprocating sliding conditions with varying frequencies and loads, existing silicon-doped aC:H coatings struggle to provide intelligent and coordinated responses to external tribological excitations. Their performance either relies on a single lubrication path at the expense of load-bearing capacity or focuses on strengthening themselves without effectively reducing interfacial shear. Therefore, developing a novel coating structure design and preparation method that can actively adapt to working conditions, intelligently distribute frictional energy, and simultaneously optimize friction reduction and wear resistance has become a critical technical challenge urgently needing breakthroughs in this field.

[0004] To date, no technical solution has been found that addresses the fundamental mechanism of the dynamic, phased bonding behavior of low-concentration silicon doped atoms, through precise process control, to pre-construct a "transitional state" structure in the coating with an optimal "strength-toughness-lubrication" potential ratio, and to enable this structure to autonomously trigger a synergistic adaptive mechanism of interfacial film formation and subsurface strengthening during friction. This invention is an innovation addressing the deficiencies and shortcomings of the aforementioned existing technologies. Summary of the Invention

[0005] To address the inherent trade-off between low friction and low wear in existing hydrogenated amorphous carbon coatings, and the limitations and unpredictable performance improvements of traditional silicon doping mechanisms, this invention aims to provide a novel coating structure design theory and implementation method. The primary objective of this invention is to reveal and utilize the phased and prioritized dynamic bonding patterns of silicon atoms during low-concentration silicon doping. Based on this, the core objective is to provide a hydrogenated amorphous carbon composite coating with intelligent tribological response characteristics. This coating can actively trigger a dual-path adaptive mechanism during reciprocating sliding friction, synergistically triggering both "interface formation of a high-quality lubricating film" and "subsurface work hardening," thereby converting frictional energy into beneficial interface modification and internal strengthening. Ultimately, under a wide range of varying operating conditions, it simultaneously optimizes the coefficient of friction and wear rate, achieving a synergistic leap in tribological performance.

[0006] First, the present invention provides a hydrogenated amorphous carbon composite coating (aC:H:Si), which, through low-concentration silicon (Si) doping, initiates and controls a non-random, staged dynamic bonding evolution of the amorphous carbon network, thereby endowing the coating with a unique "transition state" structure and the resulting intelligent tribological adaptive function.

[0007] 1. Unique microstructural evolution path (cause): The incorporation of silicon (Si) atoms into the coating and their bonding with the amorphous carbon network follow a non-random, two-stage dynamic process, which is the cornerstone that distinguishes this invention from all traditional doping theories.

[0008] Phase 1 (Network Reconstruction Period): In the initial stage of doping (corresponding to low silane flux, such as approximately 0-5 sccm), the introduced silicon atoms preferentially select for sp... 3 Hybridized carbon atoms bond to form C-Si bonds. This behavior acts like a "network scalpel," precisely disrupting the long-range, continuous, and high-stress spp in the original aC:H coating. 3 -CC rigid network effectively releases internal stress, transforming the coating from a "hard and brittle state" to a "strong and tough state".

[0009] The second stage (ordering promotion period): With a moderate increase in doping concentration (e.g., silane flux increases to 5-20 sccm), silicon atoms continue to form C-Si bonds, and their presence significantly promotes the formation of neighboring sp bonds. 2 The ordered arrangement and size (La) growth of carbon atom clusters (C=C) provide a pre-existing structural foundation for the rapid formation of a high-quality lubricating film during subsequent friction.

[0010] This phased bonding model is the fundamental structural prerequisite for realizing the subsequent intelligent adaptive behavior of the coating.

[0011] 2. Optimized macroscopic performance characteristics of the "transition state": Through the above structural adjustments, the coating is brought into an optimal performance "transition state" that is neither extremely hard nor excessively soft. The characteristic parameters of this state are as follows: Silicon atomic percentage content: 0.9 at.% to 2.08 at.%, preferably 1.36 at.% to 1.95 at.%.

[0012] Original mechanical properties: Hardness (H) is 16.5 - 19.4 GPa, and elastic modulus (Er) is 142.8–155.2 GPa. The key factor is its toughness index H. 3 / E 2 It is controlled within the preferred range of 0.23-0.31 GPa, which enables it to have good resistance to crack initiation and propagation.

[0013] Structural order: The size of the sp² carbon cluster, La, as characterized by Raman spectroscopy is >11.87 nm and increases controllably with increasing silicon content, indicating that it has an inherent and excitable graphitization potential.

[0014] 3. Intelligent dual-path friction adaptive mechanism (function): When the coating with the above-mentioned "transitional state" structure is in a reciprocating sliding friction environment, it can actively and collaboratively initiate two energy dissipation and performance optimization paths: Path 1: Interface Adaptive Lubrication. Utilizing its pre-existing graphitization potential, the coating generates and maintains a continuous, uniform, and highly ordered graphene-like transfer film in situ on the dual surface under triboelectric / thermal excitation. This transfer film is characterized by the full width at half maximum (FWHM) of the G peak in its Raman spectrum. G <150 cm -1 sp 2 The carbon cluster size La > 17 nm. This film provides extremely low interfacial shear strength, directly resulting in an ultra-low coefficient of friction.

[0015] Path Two: Subsurface Adaptive Strengthening. Due to its moderate toughness, the subsurface layer, under cyclic contact stress, not only does not soften and fail, but also undergoes significant friction-induced work hardening; that is, the instantaneous hardness of the contact area after friction is higher than the original hardness of the coating. This strengthening layer acts like a "reinforced foundation," providing stable support for the surface lubricating film and greatly enhancing its resistance to plastic deformation, plowing, and fatigue spalling, thus maintaining an extremely low wear rate. These two paths are not independent but synergistically coupled: the high-quality lubricating film reduces shear stress, protecting the subsurface layer; the strengthened subsurface layer provides mechanical assurance for the stable existence of the lubricating film. This synergistic effect achieves a qualitative leap in tribological properties.

[0016] Secondly, the present invention provides a method for preparing the above-mentioned hydrogenated amorphous carbon composite coating.

[0017] This method reliably induces and controls the aforementioned staged bonding process by precisely controlling a single key process parameter—silane gas flow rate—within a narrow optimization window, thereby achieving a coating with intelligent adaptive potential through a single deposition. The method includes the following steps: (1) Matrix cleaning and plasma activation; (2) Plasma-enhanced chemical vapor deposition was used, with acetylene as the carbon source, silane as the silicon doping source, and argon as the carrier gas and ionization gas; (3) Core process control: The silane flow rate is precisely controlled within the range of 0 sccm to 20 sccm, with the optimal value being 10 sccm. The acetylene to silane flow rate ratio is maintained between (10:1) and (40:1). Under these conditions, deposition is carried out by combining uniform substrate rotation (2-5 rpm), ion source assistance (3000 W power), and maintaining a working pressure of 0.58-0.8 Pa.

[0018] Finally, this invention provides the application of the above-mentioned hydrogenated amorphous carbon composite coating.

[0019] This coating is particularly suitable for reciprocating sliding conditions in dry or atmospheric environments where frequency and load vary. This invention is the first to explicitly reveal the frequency dependence and optimal window of the coating's performance: in the mid-frequency range of approximately 3 Hz, the frictional heat input and the material's structural response achieve optimal matching, at which point the dual-path adaptive mechanism is most efficient, simultaneously achieving the lowest coefficient of friction and optimal wear resistance. Therefore, this coating is especially suitable for high-precision sliding bearings, guide rails, engine high-pressure fuel system components, and precision transmission parts operating in the 1-5 Hz range and requiring long-term stable operation under moderate loads (2-15 N).

[0020] Compared with the closest prior art, the present invention brings outstanding substantive features and significant progress: 1. For the first time in a low-silicon-doped aC:H system, the concept of "first breaking sp" of silicon atoms was proposed and verified. 3 Network, later promoted sp 2 The discovery of a phased priority bonding model for "ordering" breaks through the traditional understanding of "random doping" and provides a new and predictable theoretical tool for precisely designing DLC ​​coating structures at the atomic scale.

[0021] 2. Successfully broke the traditional trade-off between "low friction" and "low wear" in DLC coatings. By designing a "transitional state" structure with the optimal ratio of toughness and graphitization potential, the coating can autonomously evolve during service, achieving a friction coefficient (stable below 0.04) and a wear rate (~10). -8 mm 3 The simultaneous optimization (on the order of N·m) is something that existing single performance-oriented coatings cannot achieve.

[0022] 3. An innovative dual-path collaborative adaptive mechanism of "interface lubrication-sublayer reinforcement" is proposed. The coating acts like an intelligent system, which can actively allocate energy according to friction conditions. On the one hand, it builds a low-shear interface, and on the other hand, it strengthens its own load-bearing area, realizing the "turning harm into benefit" of friction energy, thus possessing excellent adaptability to working conditions and service reliability.

[0023] 4. The complex tribological properties are directly and clearly linked to a simple and easily controlled process parameter (SiH4 flow rate), and a clear optimal process window (10 sccm) is determined. This makes the preparation of high-performance coatings highly repeatable, stable, and promising for industrialization.

[0024] 5. The study clarified the principle that the coating has an optimal performance window under medium frequency (~3 Hz) conditions, providing a quantitative scientific basis for end users to select and apply the coating, and greatly improving the success rate of application and the service life of components. Attached Figure Description

[0025] Figure 1 The diagram shows the coating preparation process flow chart and the ball-disc reciprocating sliding friction test model in the embodiments of the present invention; wherein (a) is a schematic diagram of the experimental device, (b) is the argon ion bombardment cleaning step, (c) is a schematic diagram of the silicon-containing diamond-like carbon film deposition process, and (d) is a schematic diagram of the friction performance test.

[0026] Figure 2 Cross-sectional scanning electron microscope (SEM) images of coating samples prepared at different silane (SiH4) flow rates are shown; where ae corresponds to SiH4 flow rates of 0, 5, 10, 15, and 20 sccm, respectively.

[0027] Figure 3High-resolution transmission electron microscopy (HRTEM) images of coating samples prepared under different SiH4 flow rates; where ae correspond to SiH4 flow rates of 0, 5, 10, 15, and 20 sccm, respectively.

[0028] Figure 4 The images show the high-resolution X-ray photoelectron spectroscopy (XPS) spectra of the coatings under different SiH4 flow rates, where (ae) is the C1s spectrum and (fi) is the Si 2p spectrum.

[0029] Figure 5 Based on Figure 4 Data calculation of (a) carbon bonds (sp) 3 -CC, sp 2 (a) Curves showing the relative content of silicon bonds (Si-C, Si-O) as a function of SiH4 flow rate.

[0030] Figure 6 (a) Typical Raman spectra of the coatings under different SiH4 flow rates, and (b) Raman parameter I. D / I G Curves showing the variation of SiH4 flow rate with the ratio, position of G peak (Pos(G)), full width at half maximum (FWHMG) of (c) G peak, and sp² carbon cluster size (La).

[0031] Figure 7 (ae) Surface morphology of the coating under different SiH4 flow rates, (f) corresponding histogram of surface roughness (Ra) variation, (gk) representative nanoindentation load-displacement curves, and (ln) hardness (H), elastic modulus (Er), H / E and H 3 / E 2 Summary chart of mechanical properties.

[0032] Figure 8 (ae) shows the friction coefficient variation curves of all coated samples under different frequency and load combinations, as well as a comparison graph of the average friction coefficient of each sample under different frequency and load combinations.

[0033] Figure 9 Raman spectra of the transfer films formed on the surface of 440C steel balls under different frequency and load combinations for all coated samples (ae).

[0034] Figure 10 This is a summary graph of the friction coefficient, wear rate, and corresponding Raman parameters of the transfer film for each coating sample under all test conditions (ae).

[0035] Figure 11The load-displacement curves were obtained by nanoindentation testing on different coating wear trajectory areas after friction tests under different working conditions (ae).

[0036] Figure 12 The wear rate and post-friction performance parameters (average coefficient of friction, wear trajectory hardness, H / E, H) of each coated sample are as follows: 3 / E 2 The correlation scatter plot reveals the shift in wear mechanism from brittle failure to adaptive reinforcement.

[0037] Figure 13 The performance parameters (hardness, H / E, H) of the original coatings (a, c) and (b, d) after friction under critical operating conditions (3 Hz, 8 N) are compared. 3 / E 2 A heatmap showing the correlation between La, COF, and wear rate.

[0038] Figure 14 This is a schematic diagram of the wear mechanism of the three representative coatings (SiH4-0, SiH4-10, SiH4-20) proposed in this invention during the reciprocating sliding friction process. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Example

[0040] 1. Coating preparation The hydrogenated amorphous carbon composite coating was prepared using plasma-enhanced chemical vapor deposition. A surface-polished single-crystal silicon wafer was used as the substrate, which was ultrasonically cleaned with acetone, ethanol, and deionized water, and then dried with nitrogen before being placed in the deposition chamber. A vacuum of 5 × 10⁻⁶ was then applied. -3 Below Pa, 50 sccm of argon gas was introduced, and argon plasma cleaning and activation were carried out for 30 minutes under the conditions of ion source power of 3000 W and bias voltage of -200V.

[0041] During deposition, reactive gases were introduced, with a fixed Ar flow rate of 100 sccm and a C2H2 flow rate of 200 sccm. Five sets of comparative samples were prepared by precisely controlling the SiH4 flow rate to 0, 5, 10, 15, and 20 sccm, labeled SiH4-0, SiH4-5, SiH4-10, SiH4-15, and SiH4-20, respectively. This flow rate range covers the entire process from undoped, low-doped (network reconstruction period) to moderately doped (order promotion period). Other parameters were fixed: ion source power 3000W, operating pressure 0.58-0.8 Pa, substrate rotation speed 3.75 rpm, and deposition time 120 minutes.

[0042] 2. Structural characterization and mechanical properties of the coating The coating obtained in Example 1 was characterized to verify its phased evolution and "transition state" characteristics.

[0043] Composition and Bonding (XPS Analysis): Results Figure 4 , 5 As shown. The Si content increased from 0 to 2.08 at.%. Key findings are found in Figure 5 When the SiH4 flow rate increases from 0 to 5 sccm, sp 3 -CC bond content decreases sharply, while sp 2 The -C=C bonds remain largely unchanged, which corresponds to the first stage—silicon-preferentially breaking sp bonds. 3 Network. When the flux increases from 10 to 20 sccm, the sp²-C=C bond ratio begins to decrease continuously, while the C-Si bond ratio increases. This corresponds to the second stage—silicon atom-driven sp²-C=C bond ratio. 2 The carbon clusters are ordered and stably bonded. This directly confirms the staged bonding model proposed in this invention.

[0044] Structural order (Raman analysis): such as Figure 6 As shown, with the increase of SiH4 flow rate, I D / I G With the increase of La value, FWHM G The decrease indicates that silicon doping systematically enhances the graphitization potential and order of the coating, and that this process is controllable. The SiH4-10 sample is at a balance point between potential and mechanical properties.

[0045] Surface and mechanical properties: such as Figure 7 As shown, with increasing silicon content, the coating hardness and elastic modulus generally show a decreasing trend, but the key toughness index H... 3 / E 2The hardness remained at a relatively high level of 0.26–0.29 GPa between the SiH4-5 and SiH4-15 samples. In particular, the SiH4-10 sample exhibited "transitional" characteristics: moderate hardness (~17.8 GPa), low surface roughness (Ra≈0.8 nm), and excellent toughness (H... 3 / E 2 ~0.28 GPa), laying the mechanical foundation for its subsequent intelligent tribological response.

[0046] 3. Tribological performance testing and adaptive mechanism verification The test was conducted using a ball-disc reciprocating friction tester with 440C steel balls as the mating parts and an ambient humidity of 40%. The test covered variations in frequency (1, 3, 5 Hz) and load (2, 5, 8, 11, 15 N).

[0047] Friction coefficient performance: such as Figure 8 As shown, undoped SiH4-0 failed due to brittle spalling under multiple harsh operating conditions. All doped samples exhibited superior performance. Among them, the SiH4-10 sample showed the lowest and most stable coefficient of friction under most operating conditions, especially reaching an extremely low value of 0.036 at 3Hz-8N.

[0048] Wear rate and transfer film analysis: Wear rate was calculated using a 3D profilometer. Raman analysis of wear marks on the dual-sphere ( Figure 9 10) It was found that under low-friction conditions (such as SiH4-10, 3Hz-8N), the transfer films all exhibited high La values ​​(18.91 nm) and low FWHM. G (139.4 cm) -1 This confirms the formation of Path 1 (high-quality lubricating film at the interface).

[0049] Verification of friction-induced hardening: Nanoindentation testing of wear tracks ( Figure 11 (12), confirming the existence of path two (subsurface work hardening), and this effect was most significant in moderately doped samples. Figure 11 As shown, low-doped coatings (SiH4-0 and SiH4-5) exhibit greater indentation depth and weaker recovery characteristics under high-load friction conditions, indicating significant plastic damage or brittle fracture during friction. In contrast, medium-to-high-doped coatings (SiH4-10 and SiH4-15) show curve hardening under the same conditions, suggesting that the coatings undergo structural densification or bond reconstruction under friction, achieving a certain degree of friction-induced strengthening. When the doping concentration is further increased to 20 sccm (SiH4-20), the curve change slows down, suggesting that excessively high doping concentration leads to local softening or phase separation effects in the coating, thus adversely affecting mechanical properties. Figure 12Furthermore, the wear rate and post-friction performance parameters (average coefficient of friction COF, hardness H, H / E, and Ht) of each coated sample are given. 3 / E 2 A scatter plot of the correlation was used to reveal the wear mechanism transition under different doping concentrations. The results show that when the doping concentration is low (SiH4-0 and SiH4-5), the H / E and H of the coating are relatively stable. 3 / E 2 The H / E ratio is low, the wear rate is high, and the wear is mainly dominated by brittle fracture and spalling. As the doping concentration increases to a medium level (SiH4-10 to SiH4-15), the H / E ratio of the coating and the H... 3 / E 2 The indicators were significantly improved, the wear rate was significantly reduced, and the COF was in a moderately stable range, indicating an adaptive strengthening effect during the friction process, and the wear mode changed from brittle failure to plastic regulation or ductile wear. Further increasing the doping concentration to 20 sccm (SiH4-20), the H / E and H... 3 / E 2 The wear rate decreased slightly but rebounded, indicating that overdoping may have compromised the coating structure stability and wear resistance synergy.

[0050] Performance correlation and optimal window: Figure 13 The radar chart clearly shows that only the SiH4-10 sample maintained the most complete and balanced performance profile before and after friction, proving its overall optimality. Thermal analysis further indicates a strong negative correlation between the wear rate and hardness after friction (r=-0.9), suggesting that the hardened layer dominates wear resistance; while the coefficient of friction shows a weaker correlation, indicating that the lubricating film dominates friction reduction. This data validates the independence and synergy of the "dual paths." All data indicate that the coating achieves the optimal balance between friction and wear performance at a mid-frequency of approximately 3 Hz.

[0051] In summary, based on all characterization and test data, the intelligent friction adaptive mechanism of the coating of this invention can be summarized as follows: Figure 14 As shown: SiH4-0 (undoped group): Energy is concentrated in brittle spp 3 Networks trigger crack propagation and macroscopic spalling, accompanied by high friction and failure.

[0052] SiH4-20 (overdoped group): Energy causes intense plastic flow and rapid material removal in the overly soft network, while the generation of hard wear debris may exacerbate three-body wear, resulting in a high wear rate.

[0053] SiH4-10 (the optimal group of this invention): Energy is intelligently and collaboratively dissipated: part of the energy is used to build a continuous and uniform graphene-like lubricating film at the interface (achieving ultra-low friction); another part of the energy is used to induce densification and work hardening in the subsurface layer (achieving ultra-high wear resistance). These two pathways are mutually stable and mutually reinforcing, jointly achieving a synergistic leap in performance.

[0054] Conclusion: This invention successfully prepared an aC:H:Si coating in a "tough transition state" by controlling low-concentration silicon doping (preferably SiH4 flow rate of 10 sccm) and utilizing the unique staged bonding behavior of silicon atoms. This coating exhibits an innovative "interfacial lubrication-sublayer reinforcement" dual-path adaptive mechanism during friction, thus achieving a perfect balance between ultra-low friction and ultra-high wear resistance under varying reciprocating sliding conditions, representing a significant advancement in next-generation intelligent wear-resistant lubricating coatings.

Claims

1. A low-silicon-doped hydrogenated amorphous carbon composite coating based on staged bonding control and dual-path adaptive design, characterized in that, The microstructure of this coating achieves staged bonding evolution through low-concentration silicon doping, specifically including: Phase 1: Silicon Atom Priority and sp 3 Hybridized carbon atom bonds break long-range sp bonds in the original amorphous carbon network. 3 -CC rigid frame; Second stage: Silicon atoms further promote the sp in the coating 2 Ordered arrangement and size growth of carbon clusters; During reciprocating sliding friction, the coating can synergistically trigger two adaptive behaviors: the formation of a continuous lubrication transfer film at the interface and friction-induced work hardening of the subsurface layer.

2. The coating according to claim 1, characterized in that, The coating has an initial nanoindentation hardness of 16.5 GPa to 19.4 GPa, an elastic modulus of 142.8 GPa to 155.2 GPa, and a toughness index H. 3 / E 2 is 0.23 GPa~0.31 GPa.

3. A method for preparing a low-silicon-doped hydrogenated amorphous carbon composite coating as described in any one of claims 1-2, comprising plasma-enhanced chemical vapor deposition, characterized in that, Includes the following steps: S1. Provide a cleaned and plasma-activated matrix; S2. Introduce carbon source gas acetylene, silicon doped source gas silane, and carrier gas argon into the deposition chamber; S3. By controlling the flow rate of silane gas within the range of 5 sccm to 20 sccm, silicon atoms are induced to undergo the staged bonding evolution as described in claim 1 within the growing amorphous carbon network, thereby depositing the coating.

4. The method according to claim 3, characterized in that, In step S3, the flow rate of the silane gas is controlled at 10 sccm.

5. The method according to claim 3, characterized in that, In step S3, the flow ratio of acetylene gas to silane gas is maintained in the range of (10:1) to (40:1).

6. The method according to claim 3, characterized in that, The deposition process in step S3 is carried out under the following process conditions: the working pressure of the deposition chamber is 0.58 Pa to 0.8 Pa, ion source assisted deposition is used and the ion source power is 3000 W, and the substrate rotates at a constant speed of 2 rpm to 5 rpm.

7. An application of the low-silicon-doped hydrogenated amorphous carbon composite coating as described in any one of claims 1-2, characterized in that, The coating is applied to the surface of a reciprocating sliding friction pair component that operates in a dry or atmospheric environment, the component having an operating frequency of 1 Hz to 5 Hz and a load of 2 N to 15 N.

8. The application according to claim 7, characterized in that, The reciprocating sliding friction pair components are high-precision sliding bearings, guide rails, engine high-pressure fuel system components, or precision transmission components.

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