Next Article in Journal
Design, Synthesis and Multifunctional Additive Performance of Novel Hindered Phenolic Amide–Esters
Previous Article in Journal
Tribological and Sealing Performance of Squamous Textured Mechanical Sealing Faces: Experimental and Theoretical Analysis
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Lubricants
Volume 14
Issue 5
10.3390/lubricants14050196
lubricants-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Study on the Tribocorrosion Behaviors of DLC-Si Films in a Seawater Environment

by
Xiaoxue Li
1,
Xiaoqiang Wu
1,*,
Zhiyong Zhang
2 and
Yongqiang Fu
2
1
Ordos Institute of Technology, College of Mechanical and Traffic Engineering, Eerduoshi 017000, China
2
School of Mechanical and Automotive Engineering, Qingdao University of Technology, Qingdao 266520, China
*
Author to whom correspondence should be addressed.
Lubricants 2026, 14(5), 196; https://doi.org/10.3390/lubricants14050196
Submission received: 12 April 2026 / Revised: 29 April 2026 / Accepted: 2 May 2026 / Published: 7 May 2026
(This article belongs to the Special Issue Interfacial Friction and Lubrication)
Browse Figures
Versions Notes

Abstract

The performance requirements of wear-resistant and anti-corrosion coatings for marine equipment continue to increase. Diamond-like carbon (DLC) film has become a preferred protective material due to its high hardness, low friction and chemical inertia. To reveal the tribocorrosion mechanism of Si-doped DLC films in a seawater environment, a Cr-WC-WC/C transition layer and DLC-Si films with different Si contents were prepared by high-power pulsed magnetron sputtering (HiPIMS) technology on 304 stainless steel. The tribocorrosion tests were carried out under open-circuit potential and dynamic polarization conditions in seawater. The results show that Si doping improved the tribocorrosion resistance of the films. The sample with Si content of 9.26 at.% has the lowest self-corrosion current density, the smallest volume loss, complete wear scar morphology and no obvious substrate exposure. The strengthening mechanism is attributed to Si doping, which induces the formation of a SiOx passivation film and a hydrated silica gel lubrication layer. This establishes a synergistic solid-chemical lubrication system, inhibits sp2 cluster growth, prolongs the diffusion path of corrosive media, and mitigates the damaging wear–corrosion synergy. This study confirms that moderate Si doping can significantly improve the wear resistance and corrosion resistance of DLC films in a seawater environment, and provides a theoretical basis for the design and application of carbon-based protective coatings for marine equipment.

1. Introduction

Due to the extreme complexity of the marine environment, parts suffer from both corrosive attack and other mechanical actions, including wear during operation and abrasion from repeated wave and gravel impacts, which collectively accelerate material failure. Therefore, offshore equipment usually needs to be made of high-strength, wear-resistant and anticorrosive materials, and protected by wear-resistant and anticorrosive films [1,2,3]. With the rapid development of the marine industry, the requirements for wear-resistant and anticorrosive materials are getting higher, and the research on the theory and application of wear-resistant and anticorrosive materials is becoming increasingly urgent [4,5]. Thus, high-performance protective coatings offer an economical and efficient route to enhance material properties. An ideal coating must achieve two goals: (1) effectively isolate corrosive media to boost pitting and crevice corrosion resistance and (2) provide high hardness and wear resistance against mechanical wear. Recent advances in surface engineering have led to the development of various protective coatings, such as carbon-based and hard ceramic-based wear- and corrosion-resistant coatings [6,7,8,9,10]. Among various surface-protective coating systems, Diamond-Like Carbon (DLC) film has attracted worldwide attention due to its excellent wear resistance, a low friction coefficient, chemical inertia, high hardness, and other properties. Since 1971, Aisenberg and Chabot [11] successfully prepared DLC films by ion beam deposition at room temperature for the first time. With the continuous development of preparation technology and the continuous improvement of performance-testing methods, DLC films have gradually become one of the hotspots in the field of material science.
Diamond-like carbon (DLC) films combine high hardness, excellent wear resistance, chemical inertness, and a low friction coefficient, making them promising for surface protection in harsh environments. Subsequent studies [12,13] have shown that appropriate doping with metallic or non-metallic elements can effectively tailor and optimize their overall performance. Among various doping strategies, silicon modification has attracted particular attention owing to its unique electronic structure and bonding characteristics with carbon. As an element in the same main group as carbon, Si tends to form covalent Si–C bonds rather than sp2-hybridized C=C structures, which helps regulate the bonding network and residual stress within the coating [14,15]. Raman spectroscopic investigations further reveal that the incorporation of Si extends the chemical bond length and alters atomic force constants, resulting in a gradual downshift of the G peak as the Si content increases, reflecting the evolution of the carbon hybridization state [15]. Systematic studies have demonstrated that Si doping can effectively reduce the internal stress of DLC coatings, thereby enhancing film adhesion, compactness, and comprehensive mechanical properties [16,17]. In terms of tribological performance, the introduction of Si atoms reduces the number of high-stress C–C bonds and relieves local strain accumulation, which significantly improves the mechanical stability and high-temperature tribological properties of DLC coatings [16]. For corrosion resistance, Si doping decreases film porosity and inhibits the penetration of corrosive media, thereby enhancing the corrosion protection ability of the coatings [17]. Besides elemental doping, multilayer structural design and the introduction of transition layers have also been proven effective in regulating residual stress and reducing defects such as microcracks and pinholes [18,19]. For instance, Ti interlayers and CrN-based gradient structures significantly improve the load-bearing capacity and interfacial stability of DLC coatings, which further optimizes the tribological and corrosion resistance of the coatings [18,20]. Such modifications effectively suppress electron migration and charge exchange between the substrate and corrosive medium, reducing corrosion current density and improving passive stability.
Moreover, the wear–corrosion coupling mechanism is highly complex, and the resulting material loss is far greater than the sum of individual wear and corrosion losses. This is because under tribocorrosion conditions, the synergistic effect between wear and corrosion leads to damage that significantly exceeds the sum of the two acting independently. Therefore, the material loss caused by wear–corrosion synergy cannot be ignored. Currently, researchers worldwide have gradually focused on the damage evolution and failure mechanisms of hard films under wear–corrosion coupling. For example, some researchers [21] studied the tribocorrosion properties of DLC films by applying different constant polarization voltages in a seawater environment. The results show that DLC films have lower corrosion current density under the coupling condition of tribocorrosion, and it is found that DLC films have better tribocorrosion resistance than 316 L stainless steel under this condition. Radi et al. [22] studied the effect of different concentrations of an ethanol solution on the tribocorrosion properties of DLC films under OCP conditions, and proved that DLC films have tribocorrosion resistance and can play a role in protecting the substrate. Zhang et al. [23] compared the wear resistance and corrosion resistance of hydrogen-free DLC films and hydrogen-containing DLC films under different loads in a seawater environment under OCP conditions. The results show that hydrogen-containing DLC films fail faster under high-load conditions in seawater. Vicen et al. [24] studied the tribocorrosion properties of W-DLC films and DLC films under seawater conditions. The results show that the wear rate of W-doped DLC films is lower than that of DLC films, that is, the tribocorrosion properties of W-DLC films are better than DLC films. Hatem et al. [18] studied the tribocorrosion behavior of a TiSiCN coating in a phosphate buffer solution. The coating reduced the wear rate of a medical F136 titanium alloy by 97%. This improvement stems from its nanocomposite structure—Ti(C)N grains embedded in an amorphous Si3N4/carbon dual matrix. Si effectively enhances anti-stripping ability under tribocorrosion. At 4.3–6.9 at.% Si, no coating peeling occurs and the wear scar remains flat; below 4.3 at.%, severe peeling leads to a sharp increase in wear rate. The study further points out that the film with a higher Si doping amount showed a lower friction coefficient during the tribocorrosion process, which is mainly attributed to the formation of a layer of a hydrated silica gel transfer film with a lubricating effect on the surface [18,25,26], thus optimizing the tribological properties of the coating.
Considering the above research, there are few studies on the tribocorrosion properties of doped DLC films, and the mechanism of friction and corrosion has not been studied very clearly. Therefore, this paper studies the tribocorrosion resistance of DLC with different Si doping contents in a seawater environment under OCP conditions and dynamic polarization conditions, and further studies its tribocorrosion mechanism, to provide some theoretical support for the practical application of DLC film materials to complex marine environments.

2. Experimental Details

2.1. Sample Preparation and Characterizations

The thin film deposition equipment used in this paper is a multi-functional high-density plasma application platform (New Platinum Technology (Dongguan, China) Co., Ltd., China, MS0808). The power supply used in its magnetron sputtering technology is a high-power pulse power supply, which enables it to achieve high-power pulse magnetron sputtering. This power supply is the power core of HiPIMS (High-Power Impulse Magnetron Sputtering). Its role is to output pulse voltage/current with high peak power, short pulse width and a low duty cycle, so as to stimulate the target to produce high ionization plasma, which is also the key to distinguish HiPIMS from traditional magnetron sputtering.
In this paper, the commercial 304 stainless steel (Gnee Steel (Tianjin) Co., Ltd. JIS G4305-2015 SUS304, Tianjin, China) was used as the matrix material. Because the surface oxide layer and defects of the substrate will have a significant impact on the bonding properties and growth morphology of the film, in order to reduce the influence of the surface defects of the substrate on the test results, the substrate is pretreated before deposition. Firstly, 304 stainless steel was cut into plates with a size of Φ30 × 5 mm by laser. The surface of the samples was sequentially ground with 400, 600, 800, 1000, 1200, 1500, and 2000 grit sandpapers. The surface was then polished with 20,000 grit abrasive paste to achieve a roughness (Ra) below 20 nm. Finally, the sample was subjected to ultrasonic cleaning with petroleum ether, anhydrous ethanol and deionized water for 15 min, nitrogen drying, and vacuum preservation. Before the film preparation is officially started, two key steps of vacuum–ion etching are required. First, after the sample was fixed into the cavity, it was vacuumized to 5 × 10−3 Pa and the temperature was set to 180 °C. Subsequently, ion etching was performed for 1.5 h at a bias voltage of −600 V and an Ar amount of 100 sccm, during which the vacuum chamber pressure was maintained at 0.5 Pa. This ion etching step can effectively bombard and remove impurities such as the oxide layer on the surface of the sample, thereby improving the ionic activity of the substrate surface and enhancing the bonding performance between the film and the substrate. The prepared coatings were named Si50, S75 and Si100 according to the flow rate of C6H18OSi2 (HMDSO). The detailed coating deposition parameters can be found in Table 1 in our previous research [27].
To evaluate the elastic modulus and hardness of the resulting coatings, a dynamic ultra-micro hardness tester (Shimadzu (Kyoto, Japan) Co., Ltd., DUS-211, Japan) was employed under loading–unloading conditions. The measurement parameters are as follows: a constant indentation force of 10 mN, a loading rate of 2.22 mN/s, and a penetration depth ranging from 0.14 to 0.18 μm (at the range of 7–14% of total thickness of coating). A triangular indenter (type 115) was used, and a Poisson’s ratio of 0.07 was assumed. For each sample, twelve indentations were performed at various locations to ensure statistically reliable results. Moreover, the coating’s thickness and the surface morphology of the wear track after friction tests were detected by a scanning electron microscope (SEM, Hitachi High-Tech Corporation, Regulus 8100, Minato-ku, Tokyo, Japan), and the corresponding wear scar and cross-section wear track were investigated by an optical microscope (Nanjing Jiangnan Novel Optics Co., Ltd. XJZ-6, Nanjing, Jiangsu, China) and 3D profilometer (AEP Technology, Inc. Nanomap-1000 WLI, Fremont, CA, USA), respectively.

2.2. Wear–Corrosion Performance Test

In this paper, the tribocorrosion coupling experiment is carried out by using the tribocorrosion tester. The equipment combines a reciprocating friction and wear tester and an electrochemical workstation to evaluate and test the synergistic behavior of the film in the process of friction and corrosion. The schematic diagram of the equipment is shown in Figure 1 below. Setting parameters: at room temperature; Load: 5 N; Frequency: 1 Hz; Time: 1 h; Stroke: 6 mm; Grinding ball: GCr15 ball, Diameter: 8 mm; Solution: artificial seawater; the configuration of artificial seawater is shown in Table 2 below.
The specific experimental process of the tribocorrosion test under OCP conditions is as follows: The sample was fixed, the solution was added to the container, and then the sample was immersed in the solution for an hour to stabilize the electrochemical state of the film surface. Under OCP conditions, grinding for one hour. After the friction behavior stopped, the OCP on the film surface at the beginning and end of the friction behavior was continuously recorded for 5 min. The specific experimental process of the wear–corrosion test under the condition of dynamic polarization is conducted under the condition of dynamic polarization scanning, grinding for one hour, the scanning frequency is set to 20 mV/min, the scanning voltage range is −1~+1 V, and the duration is also one hour.

3. Experimental Results and Analysis

It can be seen from the quantitative analysis of elements that with the increase in HMDSO flux, the content of Si in the film gradually increases, indicating that Si is successfully doped into the carbon-based film, and the content of Si is proportional to the flux of HMDSO. The quantitative analysis of elements and the results of hardness and elastic modulus are shown in Table 3. The results show that the elastic recovery rate of Si100 is the worst, and the elastic recovery rates of DLC, Si50 and Si75 are better and not much different. The highest hardness is pure DLC film with a value of 22.45 GPa, and the hardness of the film gradually decreases with the incorporation of Si into DLC. When a small amount of Si is doped, the hardness decreases from 21.96 GPa to 19.59 GPa with a change rate of about 2%. With the further doping of Si, the hardness decreases to 17.14 GPa. At the same time, with the increase in Si content in the film, the elastic modulus of the film gradually decreases to 147.27 GPa.
As shown in Figure 2a, the variations in OCP and the friction coefficient of five samples with time before, during and after the tribocorrosion test under OCP conditions in a seawater environment are described. The test is divided into three stages: the first part is a static OCP test for 5 min, the middle is a dynamic OCP test for 60 min of tribocorrosion, and the last is a steady-state OCP test for 5 min. The results show that the open-circuit voltage value of the five samples tends to be stable before the wear–corrosion experiment, indicating that the electrochemical state of each sample surface has reached a stable state. At the beginning of the wear–corrosion test, the OCP value of each sample decreases rapidly. This is due to the destruction of the passivation film on the surface of each sample during the friction and wear process, resulting in the destruction of the stable electrochemical state on the surface of each sample [28]. In the dynamic OCP test, the order of open-circuit voltage is Si75 (−0.38 V) > Si50 (−0.39 V) > Si100 (−0.45 V) > DLC (−0.47 V) > 304 stainless steel (−0.57 V). The results show that the Si75 film exhibits the best electrochemical response characteristics during the wear–corrosion test, and each film sample is not ground to the substrate during this process. At the same time, the results prove that the DLC film improves the tribocorrosion resistance of the substrate, and the addition of Si further improves the tribocorrosion resistance of the DLC-Si film. In addition, it is worth noting that during the tribocorrosion test, the OCP values of each sample remained stable and fluctuated to some extent, which was due to the dynamic balance of the removal rate and formation rate of the passivation film on the surface of the sample [29]. After the wear–corrosion test, the OCP value of each sample increased rapidly but did not return to the level before the start of the wear–corrosion test, indicating that the surface of each sample was destroyed during this process, and the friction and wear were interrupted. The surface of each sample re-emerged as a new passivation film. As shown in Figure 2b, by analyzing the average friction coefficient of each sample during the tribocorrosion test, the results show that the average friction coefficient of each film sample is lower than that of the 304 stainless steel substrate (0.1168), which is due to the graphitization of the DLC film itself. The DLC-Si film has a lower friction coefficient than the DLC film (0.0669), and the lowest friction coefficient of Si75 is 0.0217. Additionally, tribochemical reactions occur on the surface. Mg2+ and Ca2+ in seawater react with H2O and CO32− during friction to form sludge-like Mg(OH)2 and CaCO3. These products provide a boundary lubrication effect [30], reducing contact between the film and the ball and lowering the friction coefficient.
In order to further analyze the effect of tribocorrosion coupling on the properties of the film, Raman characterization analysis was performed on the wear scar area after the tribocorrosion test of each sample. The results after Gaussian fitting are shown in Figure 3. The results show that the ID/IG of each sample after tribocorrosion from low to high are Si75 (1.118), Si100 (1.125), Si50 (1.267) and DLC (1.527). Among them, the lowest ID/IG value is still Si75, so it shows the lowest friction coefficient. Usually, the position of G peak reflects the order degree of sp2 hybrid carbon [17]. By comparing and analyzing the position of the G peak before and after tribocorrosion of each film sample, it is found that the position of the G peak (1554.27 cm−1) of pure DLC film is relatively the highest after the friction–corrosion test, the degree of graphitization is weak, and the average friction coefficient is the highest (0.0669). The G peak of the DLC-Si film is further red-shifted, indicating that Si doping promotes the decrease in the order of sp2 clusters during the tribocorrosion process; the degree of graphitization increases and the solid lubrication effect is strengthened. Meanwhile, the hydrated reaction formed a synergistic mechanism of graphitized solid lubrication and hydrated silica gel chemical [18,25,26] synergistic lubrication. Among them, the Si75 film with the most significant red shift in the G peak (1545.58 cm−1) has the highest degree of graphitization, so the friction coefficient is the lowest (0.0217), and the friction coefficient of the remaining films is maintained at 0.0380~0.0382, but all films are lower than the 304 stainless steel substrate without DLC film protection (0.1168). FWHMG reflects the degree of disorder of the sp2 hybrid carbon in DLC films [14,17]. The larger the peak width, the higher the disorder of the sp2 cluster structure. The FWHMG (167.14) of pure DLC film is significantly smaller than that of three DLC-Si films (175.53~176.92). It is speculated that Si doping may strongly inhibit the ordering of the carbon network during tribocorrosion, so that DLC-Si maintains stable ID/IG and higher disordering.
In order to further study the tribocorrosion mechanism of the film, Figure 4 shows the SEM morphology of the wear scars of DLC, Si50, Si75 and Si100 films after tribocorrosion under open-circuit conditions and the EDS element analysis results in the corresponding region. It can be clearly seen from Figure 4a that the pure DLC film has serious furrows and defects in the wear scar area after the wear–corrosion test, and there are discrete wear particles around it, which indicates that serious abrasive wear occurs during this process, and the volume damage of the film is large. The corresponding EDS point scan results show that, in addition to C and O elements, W, Cr, Fe and other elements are also detected in the wear scar area, which indicates that some areas of the pure DLC film have been worn out, exposing the transition layer and the substrate. Compared with pure DLC, the tribocorrosion degree of DLC-Si in (b–d) is lower. Among them, the original cluster structure of the DLC-Si film surface can still be observed on the surface of Si50 and Si75 in (b,c), while the cluster structure of Si100 in (d) is completely unobservable, and furrows and some defects are observed in the tribocorrosion area, which indicates that the tribocorrosion performance of the DLC-Si film with higher Si content is poor during the tribocorrosion process. A small amount of W, Cr and Fe elements appear in Si100, indicating that excessive Si doping may reduce the mechanical properties of the film and cause slight damage to expose a small amount of the transition layer and substrate elements.
As shown in Figure 5(b1,b2), the wear scar depth of the pure DLC film is reduced to about 1 μm. The wear scar area with the DLC film is smoother than that of 304 stainless steels, and the furrow phenomenon basically disappears. However, there is a small number of deep blue and black depression areas in the pure DLC wear scar area. It is speculated that this may be due to the corrosion pits caused by pitting corrosion, which indicates that the wear–corrosion mechanism changes from abrasive wear to tribochemical wear. Therefore, the contact between the film and the ball is reduced due to the good self-lubrication and graphitization of the DLC film, which reduces the friction coefficient and wear rate. However, the corrosion resistance of pure DLC in a seawater environment is insufficient. Under the synergistic effect of corrosion and wear, the wear area of pure DLC is obviously concave. For Si-doped DLC-Si films, the introduction of Si through the regulation of the bonding structure and interfacial chemical modification is performed in order to achieve the optimization of tribocorrosion performance: as shown in (c1,c2), the Si50 sample exhibits a further reduced maximum wear scar depth of less than 0.5 μm compared to the pure DLC film, along with a smoother wear scar and shallower two-dimensional cross-section. This is because Si influences tribochemistry and plastic transfer, inducing the formation of a transfer film at the friction interface [31] that provides self-lubrication and wear resistance, thereby reducing tribocorrosion. Moreover, Si doping itself has been reported to lower the friction coefficient during tribocorrosion. I can be inferred that a similar hydration reaction occurred during the sliding process, which further reduces the friction coefficient of the DLC-Si film. However, some dark areas remain in the wear scar of the Si50 sample, indicating that pitting corrosion—though less severe than in pure DLC—is still unavoidable. As the Si content increases, the Si75 film exhibits a uniform three-dimensional surface profile with no deep wear marks and few observable pits inside the wear scar, suggesting that pitting corrosion is greatly reduced during tribocorrosion. Moreover, its two-dimensional cross-section depth is the shallowest, reflecting improved tribocorrosion resistance. However, with the further increase in Si content, the mechanical properties of the film decrease, the color change of the wear scar area of the three-dimensional profile of the Si100 film (e1) reappears, the smoothness decreases, and the wear scar area is observed again. Part of the dark area can be seen, which means that with the increase in Si content, the pitting degree of the Si100 film in the process of tribocorrosion is further increased, and its corrosion resistance is reduced. Observing the two-dimensional cross-section (e2), it was found that the depth of the wear scar area increased and the fluctuation became larger than that of the Si75 film. Therefore, with the further increase in Si, the tribocorrosion properties of Si100 films decrease. Combined with the EDS element analysis in Figure 4, the conclusion shows that with the variation tendency of O was similar to that of Si in the wear area, which confirms the occurrence of the tribo-reaction. The results show that the tribocorrosion performance of the Si75 film is the best.
The volume loss data is shown in Figure 6, which visually shows the degree of wear failure of each sample under dynamic open-circuit conditions, and its change trend is basically consistent with the aforementioned wear scar morphology and element distribution characteristics. The volume loss of 304 stainless steel reaches 2.21 × 10−4 mm3 (the maximum value of all samples), corresponding to the deep groove wear marks formed under the cyclic mechanism of Formation and destruction in seawater, which greatly reflects the effect of the corrosion–wear synergistic effect on material failure. The volume loss of pure DLC (1.64 × 10−5 mm3) is one order of magnitude lower than that of 304 steel, owing to its high hardness and sp3 structure. However, oxidative degradation in seawater makes its loss significantly higher than that of Si-doped DLC. Si50 shows a slightly lower loss (1.53 × 10−5 mm3), while Si75 exhibits the lowest loss (1.01 × 10−5 mm3). This is attributed to Si doping, which replaces sp2-bonded carbon atoms and promotes the formation of a silicon oxide passivation film on the corroded surface [32]. The formation of the passivation film reduces the number of voids on the surface of the DLC-Si film and forms a physical isolation layer, which effectively prevents ion penetration and slows down the corrosion process. The electrochemical corrosion performance of the DLC-Si film is improved, and the effect of the corrosion–wear synergistic effect on material damage is reduced. However, the loss of the Si100 film (1.56 × 10−5 mm3) increased due to the excessive Si doping, which destroyed the sp3-dominant structure of DLC, resulting in the decrease in hardness and density, weakening the wear resistance and corrosion resistance.
Figure 7 presents the polarization curves, the evolution of the friction coefficient over time, and the average friction coefficient of the five samples under polarization in a seawater environment. The polarization curves exhibit severe signal fluctuation. The core reason is the dynamic coupling between electrochemical reactions and mechanical wear, which continuously alters the electrode surface state. During the wear process, the plowing effect of abrasive particles and the “destruction–self-healing” cycles of the surface passivation film occur repeatedly. Meanwhile, the adhesion and detachment of wear debris dynamically change the active reaction sites and the effective contact area on the electrode surface, causing current density to fluctuate within a small range [31]. In addition, the friction process will inevitably lead to a certain small vibration, which is difficult to avoid. Environmental vibration will also affect polarization curve signal acquisition stability. In order to more accurately analyze the corrosion potential and self-corrosion current density of the polarization curve during the wear–corrosion test, the Tafel extrapolation method was used for the fitting analysis. The results are shown in Table 4. During the wear–corrosion test, the passive film on the sample surface is continuously removed by mechanical action as friction proceeds. This results in a decrease in corrosion potential for all samples during the wear–corrosion process [33]. Meanwhile, the passivation film undergoes repeated cycles of formation and destruction under tribocorrosion conditions. This cyclic process intensifies material loss and consequently leads to an increase in self-corrosion current density. In the electrochemical corrosion system, the decrease in self-corrosion current density directly reflects the decrease in corrosion kinetic rate. Comparing 304 stainless steel and pure DLC samples, it can be seen that the corrosion potential of pure DLC (−0.256 V) is significantly more positive than that of 304 stainless steel (−0.43 V), and its self-corrosion current density (6.31 × 10−6 A/cm2) is much lower than that of 304 stainless steel (3.16 × 10−5 A/cm2), indicating that the corrosion resistance of pure DLC film under the synergistic effect of friction–corrosion coupling is better than that of the 304 stainless steel substrate. Compared with pure DLC film, the self-corrosion current density of the Si-doped DLC film is further reduced. This is attributed to Si doping, which replaces sp2-bonded carbon atoms with silicon atoms, significantly reducing the number and size of sp2 bond clusters in the film. This suggests increased film compactness and reduced porosity [16,34]. Additionally, a silicon oxide (SiOx) film forms on the contact surface [18]. The formation of these passivation layers effectively prevents ion penetration and slows down the corrosion process. The combined effects enhance the electrochemical performance of the DLC-Si film. The Si50 film exhibits a corrosion potential of −0.63 V (more negative than that of pure DLC), while its self-corrosion current density (2.95 × 10−6 A/cm2) is further reduced. When the Si content increases to 9.26 at.%, the Si75 film shows a corrosion potential of −0.33 V, and the self-corrosion current density drops by an order of magnitude to 9.12 × 10−7 A/cm2. At this point, the self-corrosion current reaches its lowest value, meaning that the Si75 film possesses the highest wear and corrosion resistance among the five samples. However, when the Si content further increases to 10.32 at.%, the Si100 film experiences a negative shift in corrosion potential to −0.41 V, and its self-corrosion current density rises to 2.51 × 10−6 A/cm2.
Figure 7b shows the variation curve of the friction coefficient with time under the friction–corrosion coupling synergy under dynamic polarization conditions. It can be seen that the friction coefficient of 304 stainless steel is always maintained at a higher range above 0.1, while the friction coefficient of pure DLC is higher at the beginning, and then gradually decreases to a stable level, but the overall friction coefficient is still higher than that of the Si-doped DLC film, and the friction coefficient of DLC-Si film is at a lower level as a whole. The average friction coefficient data in Figure 7c further quantifies this difference. The highest average friction coefficient is seen in 304 stainless steel (0.1157). Pure DLC shows an average COF of 0.0830, which is approximately 28.2% lower than that of 304 stainless steel. For Si-doped DLC films, the average friction coefficient decreases with increasing Si content: compared to pure DLC, Si50 (0.0679), Si75 (0.0568), and Si100 (0.0479) exhibit reductions of 18.1%, 31.7%, and 42.2%, respectively. Considering the characteristics of wear–corrosion coupling, the low friction of Si-doped DLC films can be explained as follows. On the one hand, silicon significantly influences the tribochemical and plastic transfer behavior of the film, inducing the formation of a transfer film at the friction interface [14]. This transfer film possesses self-lubricating properties and wear resistance, thereby reducing the degree of tribocorrosion. Moreover, it is inferred that the self-lubricating nature of hydrated silica gel further lowers the friction coefficient during sliding. On the other hand, the excellent corrosion resistance of Si-doped DLC films (as reflected by the low icorr in Table 4) prevents the accumulation of corrosion products at the friction interface and reduces abrasive wear. This helps maintain low and stable friction performance under the interaction between electrochemical corrosion and mechanical friction. These results demonstrate that Si doping not only optimizes the corrosion resistance of DLC films but also significantly improves their anti-friction performance under wear–corrosion coupling conditions. Among the samples, the Si100 film exhibits the best friction-reducing effect under dynamic polarization, while the Si75 film offers a balanced combination of low friction and high corrosion resistance.
Figure 8 shows the Raman spectra of the samples after friction–corrosion. The ID/IG of pure DLC after friction–corrosion is 1.402, while the ID/IG of Si-doped samples gradually decrease with the increase in Si content, the degree of graphitization increases with the increase in Si content. Combined with the average friction coefficient in Figure 7c, it can be found that the change trend of ID/IG is consistent with the change trend of average friction coefficient, which further confirms the accuracy of the experimental results. With the increase in Si content, the degree of graphitization of the film increases during tribocorrosion, and the average friction coefficient decreases with the increase in Si content. The fluctuation in FWMHG (DLC: 174.52; Si50: 169.26; Si75: 172.49; Si100: 168.25) reflects the regulation effect of the Si doping amount on the disorder degree of the sp2 phase. The wide half-peak width means that the bonding mode in the wear scar area is mainly the sp2 bond. The high disorder degree maintained by moderate Si doping (Si75) can enhance the toughness of the film, while the disorder degree of excessive Si content (Si100) decreases, which is related to the ordered arrangement of Si atoms. By comparing the G peak position of each film sample after tribocorrosion, it was found that the G peak position showed a trend of red shift and then blue shift with the increase in Si content after the friction–corrosion test. Compared with the G peak position before tribocorrosion, it was found that the G peak positions of the four films were significantly red-shifted. It is speculated that this may be due to the synergistic effect of tribocorrosion, which leads to an increase in sp2 cluster disorder in the film, thus increasing the degree of graphitization [9]. This shows that the DLC-Si film has favorable tribocorrosion resistance under dynamic polarization conditions.
Through SEM morphology and EDS element analysis, Figure 9 intuitively reveals the wear scar characteristics and film integrity differences in different samples under friction–corrosion coupling conditions, which can be related to friction and electrochemical properties. As shown in Figure 9a, the wear scar area of the DLC sample shows a significant rough morphology, and the accumulation of wear particles can be seen locally. EDS analysis reveals 19.09 at.% Fe and 0.97 at.% Cr, indicating that parts of the DLC film have been destroyed, exposing the transition layer and the substrate. The presence of Cl further confirms severe film damage caused by the wear–corrosion interaction. Once the substrate is exposed, corrosion and abrasive wear occur, which is consistent with the sample’s higher friction coefficient and relatively poor corrosion resistance. As shown in Figure 9b, the wear scar of the Si50 sample exhibits significantly improved surface smoothness, with only slight friction textures remaining. The greatly reduced W and Cr contents in EDS indicate that Si doping enhances the film’s damage resistance. The Si75 sample shows the smoothest worn surface. The EDS proportions of C and Si reach 90.07 at.% and 8.37 at.%, respectively, while almost no Fe or Cr (substrate elements) are detected, indicating no significant film damage under wear–corrosion coupling. This characterization correlates well with its lowest self-corrosion current density and stable low friction coefficient, confirming that moderate Si doping improves the tribocorrosion resistance of DLC-Si films. For the Si100 sample, local large-scale damage pits appear in the wear scar, and 3.51 at.% Fe is detected by EDS, indicating partial film removal and substrate exposure. This result is consistent with the observed recovery of its self-corrosion current density, suggesting that excessively high Si content reduces the film’s mechanical properties and the synergy between wear resistance and corrosion resistance.
The three-dimensional surface profile and two-dimensional cross-section profile of Figure 10 intuitively show the degree of surface damage of each sample under friction–corrosion coupling conditions, which can form a multi-dimensional correlation with the SEM results of wear scars after wear–corrosion tests under the above dynamic polarization conditions: The three-dimensional profile of 304 stainless steel shows that the roughness and depth of the wear area (middle blue area) are significantly higher than those of other samples. The wear depth of the two-dimensional cross-section exceeds 2 μm, and the cross-section profile fluctuates violently, reflecting that it has serious abrasive tribocorrosion interaction damage under the synergistic effect of friction–corrosion coupling, which is highly consistent with its highest friction coefficient and worst corrosion resistance. As shown in Figure 10b, compared with 304 stainless steel, the three-dimensional wear zone of pure DLC exhibits improved flatness, and the cross-sectional wear depth is reduced to approximately 1 μm. However, obvious concave features remain, indicating that although the DLC film can alleviate damage, its own synergy between wear resistance and corrosion resistance is limited. This corresponds to the local damage observed in the SEM wear scar. With the introduction of Si into the DLC film (Figure 10c), the wear track of the Si50 sample becomes smoother, and the wear depth further decreases to below 1 μm. This indicates that initial Si doping enhances the film’s ability to suppress wear–corrosion coupling damage, though slight local damage still occurs. This is consistent with the exposure of a small number of substrate elements in the EDS results of Figure 9. As the Si content increases further, the Si75 sample exhibits a flat and uniform wear track, indicating the lowest degree of surface damage under wear–corrosion synergy. This feature perfectly matches the optimal corrosion resistance (low self-corrosion current density), stable low friction coefficient, and intact SEM wear scar morphology of Si75, confirming that Si doping synergistically inhibits tribocorrosion damage.
Figure 11 takes the volume loss as the macroscopic quantitative index, which more intuitively reflects the tribocorrosion damage degree of each sample under the friction–corrosion coupling condition. It can be clearly seen that the volume loss of 304 stainless steel (3.45 × 10−4 mm3) is significantly higher than that of other samples, which directly corresponds to the serious abrasive wear–corrosion interaction damage caused by a high friction coefficient and poor corrosion resistance. The volume loss of pure DLC is reduced to 2.34 × 10−5 mm3, which reflects the protective effect of the DLC film on the substrate, but is higher than that of Si-doped DLC samples. When Si is doped into the DLC film, the volume loss of the Si50 film decreases to 1.82 × 10−5 mm3 compared with that of pure DLC film, which indicates that the doping of Si improves the wear resistance and corrosion resistance of the DLC film. With the further increase in Si content, the volume loss of the Si100 film increases to 3.13 × 10−5 mm3, which is related to the decrease in mechanical properties of the film caused by an excessively high Si content.
Based on experimental characterization data and performance trends, the wear–corrosion mechanism is analyzed as follows, with the schematic diagram of the mechanism shown in Figure 12. The damage mechanism of the DLC-Si film is a synergistic coupling effect of abrasion and electrochemical corrosion. This film system achieves enhanced tribocorrosion resistance through the synergistic action of its dense microstructure, interfacial lubrication and corrosion protection; inherent high chemical inertness of the DLC film provides the foundation for corrosion protection, while the incorporation of Si elements regulates the carbon network structure, causing the number and size of sp2 bond clusters to first decrease and then increase. Among these, the Si75 sample exhibits the optimal degree of graphitization and density. This not only promotes the plastic transfer of clusters during friction to form a stable lubricating transfer film but also fills micro-pores through the SiOx oxide film generated on the surface [35,36], thereby enhancing the barrier against the penetration of corrosive ions such as Cl− and Na+. The synergistic effect of the dense structure and the passivation film enable the Si75 film to exhibit the lowest corrosion current (3.397 × 10−8 A/cm2) and the highest charge transfer resistance (4.401 × 106 Ωcm2), effectively suppressing material loss in the DLC-Si film caused by seawater corrosion. At the interfacial level, SiC suggests that it undergoes a friction-induced chemical reaction with water to form SiOx(OH)y in a seawater environment [18], and with sludge-like substances such as Mg(OH)2 and CaCO3 induced by Mg2+ and Ca2+ in seawater. The combined action of these substances reduces the contact area between the film and the beads, significantly lowering the friction coefficient. The combined effect of these two mechanisms endows DLC-Si films with superior anti-friction and wear resistance, thereby reducing material loss during the wear–corrosion process. The coupling and amplification effect of tribocorrosion is a key factor affecting film lifespan. On the one hand, mechanical damage caused by friction disrupts the integrity of the passivation layer, exposing fresh surfaces and increasing corrosion-active sites. On the other hand, the penetration of corrosive ions weakens bond strength at film defects, reduces mechanical load-bearing capacity, and exacerbates cluster peeling and abrasive wear. The Si doping level determines film performance by regulating this coupling effect. A low to moderate Si content (8.64–9.26 at.%) simultaneously optimizes lubricity and corrosion resistance, suppressing coupled damage. In contrast, excessive Si doping leads to the formation of large SiO2 particles, which induces abrasive wear and increases microdefects, accelerating ion penetration and interfacial failure, and causing a rebound in wear rate and corrosion current. In summary, under tribocorrosion conditions, the wear–corrosion mechanism of DLC-Si films is a synergistic process involving interface self-lubrication for wear reduction, passivation/densification for corrosion resistance, and the interaction between wear and corrosion.

4. Conclusions

In this study, a series of DLC-Si films with varying Si contents were systematically fabricated on 304 stainless steel substrates using HiPIMS technology. The mechanical properties and tribocorrosion behaviors of the coatings in a seawater environment were systematically investigated, and the conclusions are as follows:
(1)
Under open-circuit potential (OCP) conditions, the minimum friction coefficient of DLC-Si films reached 0.0217, with the Si75 film achieving the optimal tribocorrosion performance. Specifically, its self-corrosion current density was 9.12 × 10−7 A/cm2 and its volume loss was 1.01 × 10−5 mm3. Moderate Si doping spontaneously forms SiOx passivation and hydrated silica lubrication layers, blocking corrosive media and reducing friction to weaken wear–corrosion synergy without external electrochemical interference.
(2)
A friction coefficient of 0.0568 was observed for DLC-Si films under dynamic polarization conditions, where the Si75 film remained the top-performing sample with a volume loss of 1.62 × 10−5 mm3; excessive Si (10.32 at.%) caused notable deterioration. Polarization intensifies film–seawater electrochemical reactions, and material removal is dominated by the synergistic effect of wear and corrosion. Moderate Si promotes dense SiOx formation to resist accelerated corrosion and stabilize the film against the destruction of tribocorrosion, while excessive Si impairs film integrity and fails to withstand the coupling effect.

Author Contributions

Writing—original draft preparation, X.L.; validation, Y.F. and X.W.; formal analysis, Z.Z.; investigation, writing—review and editing Y.F.; funding acquisition, X.W. and Y.F. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by Research Startup Project for High—level Talents of Ordos Institute of Technology, Project Funded by the Central Government to Guide Local Scientific and Technological Development (No. 2025ZY0013), Project of the Natural Science Foundation of Inner Mongolia Autonomous Region (No. 2025ZDLH004). The APC was funded by Ordos Institute of Technology.

Data Availability Statement

The research data can be available by required by contacting the authors.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Dang, L.; Luo, Q. Current Status of Research on the Assessment and Prediction of Metal Corrosion in Marine Environments. Equip. Environ. Eng. 2024, 21, 88–96. [Google Scholar]
  2. Peng, S.; Bai, X. A Study on the Corrosion and Wear Properties of Stainless Steel in Marine Environments. Ph.D. Thesis, Wuhan University of Technology, Wuhan, China, 2019. [Google Scholar]
  3. Zhang, J.; Wen, S.; Hu, Y. A Discussion on Key Technical Points of Corrosion Protection for Offshore Oil Platform Structures. China Equip. Eng. 2024, 21, 229–231. [Google Scholar]
  4. Zhang, E.; Zhao, S.; Yao, J. Research on the Failure Analysis for Coating Cutters of PVD by the Finite Element. Prog. Nanotechnol. Nanomater. 2013, 2, 64–68. [Google Scholar]
  5. Nakazawa, H.; Sudoh, A.; Suemitsu, M.; Yasui, K.; Itoh, T.; Endoh, T.; Narita, Y.; Mashita, M. Mechanical and Tribological Properties of Carbon, Nitrogen-coincorporated Diamond-like Carbon Films Prepared by Reactive Radio-frequency Magnetron Sputtering. Diam. Relat. Mater. 2010, 519, 24–30. [Google Scholar] [CrossRef] [Scilit]
  6. Liu, B.; Wang, H.; Fang, Z. Development Trends in Anti-Corrosion Coatings for Naval Vessels. Corros. Sci. Prot. Technol. 2007, 4, 287–289. [Google Scholar]
  7. Härkönen, E.; Kolev, I.; Díaz, B.; Światowska, J.; Maurice, V.; Seyeux, A.; Marcus, P.; Fenker, M.; Toth, L.; Radnoczi, G.; et al. Sealing of hard CrN and DLC coatings with atomic layer deposition. ACS Appl. Mater. Interfaces 2014, 6, 1893–1901. [Google Scholar] [CrossRef] [Scilit]
  8. Li, S.; Lee, J.S.; Hyeon, T.; Suslick, K.S. Catalytic hydrodenitrogenation of indole over molybdenum nitride and carbides with different structures. Appl. Catal. A Gen. 1999, 181, 1–9. [Google Scholar] [CrossRef] [Scilit]
  9. Shan, L.; Wang, Y.; Li, J.; Cheng, J. Tribological Properties of TiN, TiCN, and CrN Coatings in a Seawater Environment. Chin. J. Surf. Eng. 2013, 26, 86–92. [Google Scholar]
  10. Song, Y.; Gao, Y.; Wang, C.; Peng, K. Effect of Different Mo Content on the Friction and Wear Properties of CrMoN Thin Films. J. Vac. Sci. Technol. 2016, 36, 886–890. [Google Scholar]
  11. Aisenberg, S.; Chabot, R. Ion-beam deposition of thin films of diamondlike carbon. J. Vac. Sci. Technol. 1971, 42, 2953–2958. [Google Scholar]
  12. Cao, H.; Qi, F.; Ouyang, X.; Zhao, N.; Zhou, Y.; Li, B.; Luo, W.; Liao, B.; Luo, J. Effect of Ti transition layer thickness on the structure, mechanical and adhesion properties of Ti-DLC coatings on aluminum alloys. Materials 2018, 11, 1742. [Google Scholar] [CrossRef] [Scilit] [PubMed]
  13. Wu, X.; Chen, T.; Ge, Z.; Ruan, J.; Zhang, J. Study on the Tribological Properties of N/Si Co-doped DLC Films under Different Humidity Conditions. J. Tribol. 2017, 37, 501–509. [Google Scholar]
  14. Guo, P.; Jia, Q.; Meng, S.; Liu, G.; Lai, Z.; Wen, X.; Zhang, B. Effect of Element Doping on the Tribological Properties of Diamond-Like Carbon Films. Chin. J. Surf. Eng. 2021, 34, 19–29. [Google Scholar]
  15. Huang, B.; Liu, L.-T.; Han, S.; Du, H.-M.; Zhou, Q.; Zhang, E.-G. Effect of deposition temperature on the microstructure and tribological properties of DLC-Si coatings prepared by PECVD. Diam. Relat. Mater. 2022, 129, 109345. [Google Scholar] [CrossRef] [Scilit]
  16. Deng, H.; Chen, D.; Wang, Y.; Zhou, Y.; Gao, P. Effects of silicon on microstructure and corrosion resistance of diamond-like-carbon film prepared on 2024 aluminum alloy by plasma-enhanced chemical vapor deposition. Diam. Relat. Mater. 2020, 110, 108144. [Google Scholar] [CrossRef] [Scilit]
  17. Lubwama, M.; Corcoran, B.; Rajani, K.; Wong, C.; Kirabira, J.; Sebbit, A.; McDonnell, K.; Dowling, D.; Sayers, K. Raman analysis of DLC and Si-DLC films deposited on nitrile rubber. Surf. Coat. Technol. 2013, 232, 521–527. [Google Scholar] [CrossRef] [Scilit]
  18. Hatem, A.; Lin, J.; Wei, R.; Torres, R.D.; Laurindo, C.; de Souza, G.B.; Soares, P. Tribocorrosion behavior of low friction TiSiCN nanocomposite coatings deposited on titanium alloy for biomedical applications. Surf. Coat. Technol. 2018, 347, 1–12. [Google Scholar] [CrossRef] [Scilit]
  19. He, D.; Liang, R.; Pan, X.; Shang, L.; Cao, J. Effect of interlayer thickness on impact damage behaviors of Cr3C2-NiCr/DLC duplex coatings. Chin. J. Surf. Eng. 2025, 51, 58366–58378. [Google Scholar] [CrossRef] [Scilit]
  20. Hu, Y.; He, M. Effect of Nitrogen Flow Rate on the Tribological Properties and Corrosion Behavior of CrN-DLC Films. Mater. Prot. 2023, 56, 36–43. [Google Scholar]
  21. Ye, Y.; Wang, Y.; Ma, X.; Zhang, D.; Wang, L.; Li, X. Tribocorrosion behaviors of multilayer PVD DLC coated 304L stainless steel in seawater. Diam. Relat. Mater. 2017, 79, 70–78. [Google Scholar] [CrossRef] [Scilit]
  22. Radi, P.A.; Vieira, A.; Manfroi, L.; Nass, K.C.d.F.; Ramos, M.A.R.; Leite, P.; Martins, G.V.; Jofre, J.B.F.; Vieira, L. Tribocorrosion and corrosion behavior of stainless steel coated with DLC films in ethanol with different concentrations of water. Ceram. Int. 2019, 45, 9686–9693. [Google Scholar] [CrossRef] [Scilit]
  23. Zhang, Y.; Li, H.; Cui, L.; Yang, W.; Ma, G.; Chen, R.; Guo, P.; Ke, P.; Wang, A. Comparative study on tribocorrosion behavior of hydrogenated/hydrogen-free amorphous carbon coated WC-based cermet in 3.5 wt.% NaCl solution. Corros. Sci. 2024, 227, 111738. [Google Scholar] [CrossRef] [Scilit]
  24. Vicen, M.; Kajánek, D.; Trško, L.; Bokůvka, O.; Buchtík, M.; Florková, Z.; Frkáň, M. Improving of 100Cr6 steel corrosion and wear properties in simulated sea water environment by Tungsten-Doped DLC coating. Materials 2023, 16, 4334. [Google Scholar] [CrossRef] [Scilit] [PubMed]
  25. Gilmore, R.; Hauert, R. Comparative study of the tribological moisture sensitivity of Si-free and Si-containing diamond-like carbon films. Surf. Coat. Technol. 2000, 133, 437–442. [Google Scholar] [CrossRef] [Scilit]
  26. Li, X.; Luo, Y.; Li, J.; Cao, X.; Wang, L.; Zhang, G.; Luo, Z. Predominant role of fatigue crack evolution and tribo-chemistry on tribological behavior of Si-DLC film under different relative humidity. Tribol. Int. 2023, 181, 108326. [Google Scholar] [CrossRef] [Scilit]
  27. Zhang, Z.; Liu, C.; Fu, Y.; Guo, F.; Jia, D.; Wang, J.; Cao, L.; Wu, X.; Li, X. Achieving low friction and high corrosion resistance DLC-Si films by HiPIMS. Surf. Coat. Technol. 2025, 522, 133148. [Google Scholar] [CrossRef] [Scilit]
  28. Jantschner, O.; Field, S.; Holec, D.; Fian, A.; Music, D.; Schneider, J.; Zorn, K.; Mitterer, C. Origin of temperature-induced low friction of sputtered Si-containing amorphous carbon coatings. Acta Mater. 2015, 82, 437–446. [Google Scholar] [CrossRef] [Scilit]
  29. Fu, Y.; Zhou, F.; Wang, Q.; Zhang, M.; Zhou, Z. Electrochemical and tribocorrosion performances of CrMoSiCN coating on Ti-6Al-4V titanium alloy in artificial seawater. Corros. Sci. 2020, 165, 108385. [Google Scholar] [CrossRef] [Scilit]
  30. Wang, J.; Chen, B.; Yan, F. Effects of Seawater Composition on Seawater Lubrication Performance. Lubr. Seal. 2011, 36, 1–5. [Google Scholar]
  31. Chen, X.; Zhang, C.; Kato, T.; Yang, X.-A.; Wu, S.; Wang, R.; Nosaka, M.; Luo, J. Evolution of tribo-induced interfacial nanostructures governing superlubricity in a-C:H and a-C:H:Si films. Nat. Commun. 2017, 8, 1675. [Google Scholar] [CrossRef] [Scilit]
  32. Wei, X.; Lu, S.; Ding, J.; Zheng, S.; Chen, Z.; Lu, J.; Liu, Z.; Yin, P.; Du, N.; Yang, W.; et al. Enhanced corrosion resistance of a novel periodic multilayered Si/(Si, N)-DLC coating against simulated coal mine water. Ceram. Int. 2024, 50, 49385–49399. [Google Scholar] [CrossRef] [Scilit]
  33. Wang, Y.; Li, J.; Dang, C.; Wang, Y.; Zhu, Y. Influence of carbon contents on the structure and tribocorrosion properties of TiSiCN coatings on Ti6Al4V. Tribol. Int. 2017, 109, 285–296. [Google Scholar] [CrossRef] [Scilit]
  34. Bociaga, D.; Sobczyk-Guzenda, A.; Komorowski, P.; Balcerzak, J.; Jastrzebski, K.; Przybyszewska, K.; Kaczmarek, A. Surface characteristics and biological evaluation of Si-DLC coatings fabricated using magnetron sputtering method on Ti6Al7Nb substrate. Nanomaterials 2019, 9, 812. [Google Scholar] [CrossRef] [Scilit]
  35. Zhang, T.F.; Wan, Z.X.; Ding, J.C.; Zhang, S.; Wang, Q.M.; Kim, K.H. Microstructure and high-temperature tribological properties of Si-doped hydrogenated diamond-like carbon films. Appl. Surf. Sci. 2018, 435, 963–973. [Google Scholar] [CrossRef] [Scilit]
  36. Choi, J.; Nakao, S.; Miyagawa, S.; Ikeyama, M.; Miyagawa, Y. The effects of Si incorporation on the thermal and tribological properties of DLC films deposited by PBII&D with bipolar pulses. Surf. Coat. Technol. 2007, 201, 8357–8361. [Google Scholar]
Lubricants 14 00196 g001
Figure 1. The schematic diagram of the tribocorrosion testing machine.
Figure 1. The schematic diagram of the tribocorrosion testing machine.
Lubricants 14 00196 g001
Lubricants 14 00196 g002
Figure 2. Each sample under dynamic open-circuit conditions: (a) open-circuit potential and friction coefficient curve; (b) average friction coefficient.
Figure 2. Each sample under dynamic open-circuit conditions: (a) open-circuit potential and friction coefficient curve; (b) average friction coefficient.
Lubricants 14 00196 g002
Lubricants 14 00196 g003
Figure 3. (a) Raman spectra and (b) FWHMG, G peak wavenumber, ID/IG of all samples after wear–corrosion under dynamic open-circuit conditions.
Figure 3. (a) Raman spectra and (b) FWHMG, G peak wavenumber, ID/IG of all samples after wear–corrosion under dynamic open-circuit conditions.
Lubricants 14 00196 g003
Lubricants 14 00196 g004
Figure 4. SEM and EDS of wear scar after wear–corrosion test under dynamic open-circuit conditions: (a) DLC; (b) Si50; (c) Si75; (d) Si100.
Figure 4. SEM and EDS of wear scar after wear–corrosion test under dynamic open-circuit conditions: (a) DLC; (b) Si50; (c) Si75; (d) Si100.
Lubricants 14 00196 g004
Lubricants 14 00196 g005
Figure 5. After tribocorrosion test under dynamic open-circuit conditions, each sample (a) 304, (b) DLC, (c) Si50, (d) Si75, (e) Si100, (a1–e1) 3–D contour and (a2–e2) 2–D profiles of wear track.
Figure 5. After tribocorrosion test under dynamic open-circuit conditions, each sample (a) 304, (b) DLC, (c) Si50, (d) Si75, (e) Si100, (a1–e1) 3–D contour and (a2–e2) 2–D profiles of wear track.
Lubricants 14 00196 g005
Lubricants 14 00196 g006
Figure 6. The volume loss of each sample after wear–corrosion test under dynamic open-circuit conditions.
Figure 6. The volume loss of each sample after wear–corrosion test under dynamic open-circuit conditions.
Lubricants 14 00196 g006
Lubricants 14 00196 g007
Figure 7. Polarization curves of each sample (a) under dynamic polarization conditions; (b) friction coefficient curve; (c) average friction coefficient.
Figure 7. Polarization curves of each sample (a) under dynamic polarization conditions; (b) friction coefficient curve; (c) average friction coefficient.
Lubricants 14 00196 g007
Lubricants 14 00196 g008
Figure 8. Raman spectra of each sample after tribocorrosion under dynamic polarization conditions (a) Raman spectra and (b) FWHMG, G peak wavenumber, ID/IG.
Figure 8. Raman spectra of each sample after tribocorrosion under dynamic polarization conditions (a) Raman spectra and (b) FWHMG, G peak wavenumber, ID/IG.
Lubricants 14 00196 g008
Lubricants 14 00196 g009
Figure 9. SEM and EDS of wear scar after wear–corrosion test under dynamic polarization conditions: (a) DLC; (b) Si50; (c) Si75; (d) Si100.
Figure 9. SEM and EDS of wear scar after wear–corrosion test under dynamic polarization conditions: (a) DLC; (b) Si50; (c) Si75; (d) Si100.
Lubricants 14 00196 g009
Lubricants 14 00196 g010
Figure 10. After tribocorrosion test under dynamic polarization conditions, (a) 304, (b) DLC, (c) Si50, (d) Si75, (e) Si100; (a1–e1) three-dimensional contour; (a2–e2) two-dimensional cross-section profile.
Figure 10. After tribocorrosion test under dynamic polarization conditions, (a) 304, (b) DLC, (c) Si50, (d) Si75, (e) Si100; (a1–e1) three-dimensional contour; (a2–e2) two-dimensional cross-section profile.
Lubricants 14 00196 g010
Lubricants 14 00196 g011
Figure 11. The volume loss of each sample after wear–corrosion test under dynamic polarization conditions.
Figure 11. The volume loss of each sample after wear–corrosion test under dynamic polarization conditions.
Lubricants 14 00196 g011
Lubricants 14 00196 g012
Figure 12. Diagram of tribocorrosion mechanisms, (a) tribocorrosion model of DLC tribo-pairs in seawater environment, (b) locally magnified friction interface, and (c) its tribocorrosion behaviors mechanism.
Figure 12. Diagram of tribocorrosion mechanisms, (a) tribocorrosion model of DLC tribo-pairs in seawater environment, (b) locally magnified friction interface, and (c) its tribocorrosion behaviors mechanism.
Lubricants 14 00196 g012
Table 1. DLC-Si thin films deposition process [27].
Table 1. DLC-Si thin films deposition process [27].
Film StructureDeposition
Process		Flow Rate (sccm)Target Power (kW)Bias
Voltage (V)		Time (min)
ArC2H2HMDSOCrWC
Transition layerCr130//3/20060
WC110///330
WC/C110///0.590
FilmDLC-Si (Si50, Si75, Si100)1107550,
75, 100		//150
Table 2. Artificial seawater chemical composition ingredients (g/L).
Table 2. Artificial seawater chemical composition ingredients (g/L).
NaClMgClNa2SO4CaCl2KClNaHCO3KBrH3BO3SrCl2NaF
24.53005.20004.09001.16000.69500.20100.10010.02700.02500.0030
Table 3. Si content, mechanical properties and the thickness of prepared films [27].
Table 3. Si content, mechanical properties and the thickness of prepared films [27].
SampleSi (at.%)Hardness (GPa)Elastic Modulus (GPa)Thickness (μm)
DLC022.45 ± 1.3172.85 ± 3.33.2
Si508.6421.96 ± 1.1180.09 ± 2.42.9
Si759.2619.59 ± 0.8176.50 ± 2.33.0
Si10010.3217.14 ± 1.1147.27 ± 2.82.8
Table 4. Corrosion potential and self-corrosion current density of each sample under dynamic polarization conditions.
Table 4. Corrosion potential and self-corrosion current density of each sample under dynamic polarization conditions.
Ecorr (V)icorr (A/cm2)
304−0.433.16 × 10−5
DLC−0.2566.31 × 10−6
Si50−0.632.95 × 10−6
Si75−0.339.12 × 10−7
Si100−0.412.51 × 10−6
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Li, X.; Wu, X.; Zhang, Z.; Fu, Y. Study on the Tribocorrosion Behaviors of DLC-Si Films in a Seawater Environment. Lubricants 2026, 14, 196. https://doi.org/10.3390/lubricants14050196

AMA Style

Li X, Wu X, Zhang Z, Fu Y. Study on the Tribocorrosion Behaviors of DLC-Si Films in a Seawater Environment. Lubricants. 2026; 14(5):196. https://doi.org/10.3390/lubricants14050196

Chicago/Turabian Style

Li, Xiaoxue, Xiaoqiang Wu, Zhiyong Zhang, and Yongqiang Fu. 2026. "Study on the Tribocorrosion Behaviors of DLC-Si Films in a Seawater Environment" Lubricants 14, no. 5: 196. https://doi.org/10.3390/lubricants14050196

APA Style

Li, X., Wu, X., Zhang, Z., & Fu, Y. (2026). Study on the Tribocorrosion Behaviors of DLC-Si Films in a Seawater Environment. Lubricants, 14(5), 196. https://doi.org/10.3390/lubricants14050196

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop