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Article

Friction Behavior of Molybdenum Disulfide/Polytetrafluoroethylene-Coated Cemented Carbide Fabricated with a Spray Technique in Dry Friction Conditions

by
Li Zhang
and
Wenlong Song
*
School of Mechanical and Electrical Engineering, Jining University, Qufu 273155, China
*
Author to whom correspondence should be addressed.
Coatings 2025, 15(3), 324; https://doi.org/10.3390/coatings15030324
Submission received: 6 February 2025 / Revised: 22 February 2025 / Accepted: 9 March 2025 / Published: 11 March 2025
(This article belongs to the Special Issue Advancement in Heat Treatment and Surface Modification for Metals)
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Versions Notes

Abstract

:
Cemented carbide has a relatively high surface friction coefficient, which can result in increased wear and energy consumption during friction, ultimately impacting service life and efficiency. In order to improve the tribological properties of the traditionally cemented carbide, the MoS2 and PTFE (25 wt.%) mixed powders, which were blended with Polyamide-imide (PAI) as the adhesive, were sprayed on the carbide surface at 70 °C. Tests were used to measure the performance of MoS2/PTFE-coated carbide, such as surface micrographs and cross-section micrographs, surface roughness, adhesion strength between coatings and substrate, and surface microhardness. Sliding friction tests were performed to investigate the friction performance. The test results showed that the adhesion strength between the coatings and substrate was up to 36 N, the hardness was about 0.42 GPa, and the friction coefficient was reduced by about 70%. The lower shear strength of MoS2/PTFE coatings led to the reduction of friction and wear. The main wear mechanisms of MoS2/PTFE coatings were surface abrasion and coating flaking. The MoS2/PTFE coatings present a promising approach to enhance the friction performance of traditional cemented carbide.

1. Introduction

Cemented carbide is widely used for its excellent mechanical properties, including good toughness, high hardness, and excellent wear resistance. These properties make cemented carbide the material of choice for various applications [1,2], including cutting tools, engine components, and sealing and bearing parts. However, in the absence of proper lubrication and cooling, particularly during machining processes, cemented carbide can experience high friction, leading to wear problems that significantly shorten the life of tools and components. This issue becomes even more critical in sustained or high-performance applications, where wear resistance and longevity are paramount. Therefore, there is a pressing need for enhanced solutions to reduce friction and improve the lifespan of cemented carbide.
One effective approach to improving the friction properties of cemented carbide is the use of coatings. These coatings can generally be categorized into two types on the basis of microhardness: one hard and one soft. Hard coatings, such as metal carbides [3], oxides [4], and nitrides [5], are known for their high surface hardness and excellent wear resistance. By forming a protective layer, hard coatings enhance the durability [6] and overall performance [7,8] of cemented carbide, making them particularly effective in applications like machining and stamping [9,10].
In contrast, soft coatings are commonly used to reduce friction and prevent wear by forming a lubricating layer between surfaces. Soft coatings are typically made from materials with low shear strength, which enables them to flow easily and provide effective lubrication [11]. Materials such as metal sulfide have been extensively studied as soft coatings for the cemented carbide. Research consistently shows that these soft coatings can clearly reduce the friction coefficient and wear of a substrate [12]. They have proven to be particularly effective in applications where friction control is crucial, including precision machinery and automotive and aerospace components [13]. Soft coatings underscore their potential to enhance the performance and longevity of cemented carbide in demanding tribological environments [14,15].
MoS2 (molybdenum disulfide) [16,17] and polytetrafluoroethylene (PTFE) [18,19] are two widely used solid lubricants in industry. They are renowned for their exceptional lubrication properties, outstanding wear resistance, and remarkable high-temperature stability [20]. The combination of the two materials in MoS2/PTFE composite coatings represents an innovative approach to solid lubrication, where the individual lubricants complement and enhance each other’s performance [21]. Numerous studies have investigated the attributes of MoS2/PTFE coatings, revealing that these coatings can significantly extend the service time of a substrate [22,23], as well as improve the adhesion strength of the transfer film on the counterpart surface [24,25]. These benefits make MoS2/PTFE coatings particularly valuable for reducing the friction and wear of components [26,27]. However, there remains a gap in the research regarding the frictional properties of MoS2/PTFE-coated cemented carbide. Further exploration into this domain could provide valuable insights into optimizing the properties of MoS2/PTFE in such applications.
Soft coatings can be applied using several techniques, each with its own advantages and limitations. The depositing methods for soft coatings include polishing, physical vapor deposition (PVD), and spraying technology [11,16]. Polishing techniques cannot provide steady lubrication owing to poor adhesion performance with a substrate, which limits the practical utility. PVD is effective for creating thin, dense coatings, and has a relatively low deposition rate; however, its coating is too thin to be suitable for many industrial applications. On the other hand, spray technology offers a promising alternative for applying soft coatings, as they can produce thicker layers at a faster rate, improving the adhesion and efficiency of the coating process. Spray coating also allows for better control over the thickness and uniformity of the coating, making this method more adaptable for industry applications.
In this research, MoS2/PTFE coatings were first prepared on the surface of cemented carbide using spray technology. The experiments were used to assess the mechanical and physical performance, and the tribological behavior of coated cemented carbide was also evaluated and compared with the uncoated one with friction tests. This research aims to investigate the potential benefits of MoS2/PTFE coatings in decreasing friction and improving the wear resistance of cemented carbide in industrial applications that require low friction but cannot be cooled and lubricated with fluid.

2. Materials and Methods

2.1. Coating Fabrication

In this research, WC/TiC/Co-cemented carbide was selected as the substrate. Its main performance is listed in Table 1. MoS2 and PTFE powders were chosen for their lubricating and anti-friction properties, which are beneficial for improving the wear resistance and operational efficiency of the carbide. The size of MoS2 powder was about 2–6 μm, and that of PTFE powder was about 4–10 μm.
Before depositing the coating, the carbide substrate was degreased to remove the surface contaminants in order to enhance the adhesion performance. The coating preparation involved a mixture of MoS2 and PTFE (25 wt.%) powders, which were blended with Polyamide-imide (PAI) as the adhesive. This mixture was stirred for 50 min using a magnetic device to ensure the uniform dispersion of the particles, followed by a 45 min ultrasonic treatment to further disperse the powders. Once the powder mixture was thoroughly dispersed, the mixture was heated to 70 °C and then sprayed to the carbide surface at a pressure of 0.45 MPa. Finally, the samples were put in a furnace at 310 °C for 35 min and then slowly cooled in the furnace to stabilize the coating and ensure uniform formation.
To test the adhesion strength of the coating, a material property tester (MT-4000, Lanzou Equipment Technology Co., Ltd., Lanzou, China) with a measurement accuracy of 0.1 N was used. The tester uses a diamond stylus with a diameter of 0.4 mm to perform a scratch test, which measures the adhesion force between the surface and coating. The scratch test was conducted with a travel distance of 6 mm and a load of 60 N at an increasing rate of 60 N/min.
The surface hardness was assessed using a micro-hardness tester (MH-6, Shanghai Measuring Equipment Co., Ltd., Shanghai, China) with a measurement error of 3% at a load of 0.1 N. This low load was chosen to avoid any interference from the substrate’s property. The test process included a loading period of 30 s followed by a 15 s holding time. The surface roughness was measured using a surface profilometer (Wyko NT9300, Veeco Inc., Plainview, NY, USA) with a measurement accuracy of Ra 0.01 μm.

2.2. Friction and Wear Tests

To investigate the tribological performance of MoS2/PTFE-coated carbide, sliding tests were conducted with a ball-on-disk oscillating tribometer (Jinan Hengxu Measuring Technology Co., Ltd., Jinan, China).
To provide a comparative analysis, the tribological performance of carbide with and without coating, a WC/6%Co ball with a diameter of 6 mm, was chosen as the counterpart. The sliding test was carried out at a load from 20 N to 80 N, and the sliding speed ranged from 4 mm/s to 10 mm/s. Additionally, each test involved a stroke length of 6 mm and time of 15 min. The data represent the average values of four tests.
Following the sliding tests, a scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) provided a comprehensive understanding of the wear mechanisms, facilitating an in-depth investigation into the wear and distribution of elements on the wear surface. This proved invaluable in unraveling the underlying mechanisms responsible for the observed tribological behavior of both the MoS2/PTFE-coated and uncoated carbides.

3. Results and Discussion

3.1. Coating Properties

Figure 1 presents the SEM micrographs of the MoS2/PTFE coating surface. From Figure 1a,b, it is evident that the MoS2/PTFE coatings exhibit a dense and steady structure, with clearly discernible grain boundaries of the solid lubricant phase. The distribution of the components within the composite appears relatively uniform, indicating good dispersion and integration of the MoS2 and PTFE particles within the matrix. The surface appears relatively smooth and continuous.
In the cross-section micrographs of MoS2/PTFE coatings shown in Figure 2, the coatings reveal a relatively homogeneous and compacted condition, with a consistent thickness of approximately 13 μm. The coatings adhere well to the underlying cemented carbide, with no noticeable coating segregation or delamination. This uniformity in thickness and the absence of defects are essential for ensuring the mechanical stability and performance of the coating during operational conditions.
Figure 3 demonstrates the surface topography of both coated and uncoated carbides tested using an NT9300 optical profilometer. The result clearly shows that the coated carbide has a relatively rough surface compared with the uncoated carbide. The coated surface roughness is approximately Ra 0.36 μm, while the uncoated carbide was about Ra 0.32 μm.
The adhesion strength between the coating and substrate was evaluated with a scratch test, where the friction force and friction coefficient were measured. Figure 4 presents the scratch curve of the coated sample. Initially, when the load was low, the friction coefficient remained relatively stable, and the friction force slowly increased, indicating that there was little wear or disruption of the coating. However, as the load increased to 30–32 N, both the friction coefficient and friction force started to increase sharply. This rapid increase in signal indicated that the coating started to wear away. Once the load surpassed 36–40 N, the curves of the friction force and coefficient reached higher values, suggesting that the coating had been completely delaminated and the substrate had been exposed. Then, the adhesion strength of the composite coatings was at least 36–40 N.
In comparison with the previous results from the authors’ other works, where the adhesion forces of similar coatings were found to be in the range of 40 N to 58 N [28,29], the adhesion strength of the MoS2/PTFE composite coatings was relatively low. This could affect the self-lubricating capabilities and service life of the coatings under higher load conditions.
To better investigate the adhesion strength between the coating and substrate, Figure 5 presents scratch micrographs and corresponding element analyses of scratch tracks. In Figure 5a–c, significant damage to the coating can be observed, including deep scratches and coating detachment along the track. The element analysis (Figure 5d–f) reveals that only a small amount of coating material remains in the scratch track, while obvious carbide elements are detected. This exposure of substrate corresponds to the observed increases in friction force and friction coefficient during the scratch test.
Finally, the primary property of MoS2/PTFE coatings is summarized in Table 2. The result shows that the surface hardness of the coated carbide is 0.42 ± 0.05 GPa, which is approximately 97% lower than the carbide one (Table 1), which was about 16.2 ± 0.1 GPa. The reduction in hardness is expected, as the composite coatings are designed primarily for lubrication and wear resistance rather than for hardness. The relatively soft coatings aid in reducing the friction during sliding but this also means that the coatings are more susceptible to wear under high load conditions [29,30].

3.2. Friction Performance

Figure 6 presents the friction coefficient curves of carbide under different loads. As indicated in this figure, it is evident that the coated carbide demonstrates a clear decrease in friction coefficient compared to the uncoated one.
In the case of the uncoated carbide, the friction coefficient initially experienced a noticeable increase. This early rise can be due to the establishment of surface contact, where the asperities on both surfaces engage and interlock. The initial increase in the friction coefficient was somewhat moderate, largely because of the smoothness of the friction pair surfaces [30,31].
As the test progressed into the steady friction phase, a more pronounced trend was observed. The friction coefficient of carbide gradually decreased from an initial range of 0.35–0.45 to a steady state range of 0.28–0.38 when the load increased up to 80 N. During this stage, the friction curve showed increased fluctuation, indicative of the evolving surface roughness due to wear and material transfer between the friction pairs.
However, the MoS2/PTFE-coated carbide exhibited a more stable friction coefficient throughout the test. The friction coefficient ranged from 0.08 to 0.13 at the start of the test, and only slightly increased to a range of 0.11 to 0.15 as the load increased. This small fluctuation of friction coefficient is likely due to the self-lubricating properties of MoS2/PTFE, which significantly reduces wear and friction by forming a layer that prevents direct contact [29,30].
Figure 7 displays the friction coefficient curves under different speeds. The results from Figure 7 exhibit similarities to those in Figure 6. However, the change in sliding speed had minimal impact on the tribological behavior of the carbide, indicating that the friction properties of both the uncoated and coated carbides are relatively unaffected by changes in sliding speed.
As the sliding speed increased gradually to 10 mm/s, the frictional coefficient of uncoated carbide kept in the range of 0.26–0.38 in the stable stage. Meanwhile, the MoS2/PTFE-coated carbide kept a low and consistent friction coefficient, with values consistently ranging from 0.09 to 0.15. In comparison with the previous results of the authors’ other works, MoS2/PTFE coatings are more effective in reducing the friction coefficient of carbide [29,30], which in turn enhances the overall performance and durability of carbide.

3.3. Wear Morphology Analysis of Sample

To effectively evaluate the tribological property of the uncoated sample, the surface was tested with SEM and EDS after a 15 min sliding friction test. As depicted in Figure 8, the SEM micrographs reveal substantial mechanical plowing, microcracks, and material adhesion on the worn surface. The mechanical plowing is indicative of surface disruption caused by serious friction. Microcracks signify the extent of mechanical damage and the initiation of material degradation. Additionally, the adhesion of the material suggests that some material was transferred from the counterpart to the substrate.
To further investigate the composition of the adhesions, an EDS analysis was conducted in Figure 8c,d. The results revealed that the adhesion material primarily consisted of WC and Co elements. This indicates that the interface between the two surfaces became damaged, leading to the transfer of material from one surface to another.
The presence of such severe adhesion on the worn surface notably impacted the surface roughness of the uncoated carbide. A rough surface typically leads to increased fluctuations during the sliding test, as evidenced in Figure 6 and Figure 7. The fluctuations can result in instability and a decrease in the performance of the surface. The primary wear mechanisms include adhesion wear, mechanical plowing, and microcrack formation [31].
In contrast, Figure 9 shows the SEM micrographs and EDS analyses of the coated carbide. The results highlight a clear difference in the wear property between the two samples. The MoS2/PTFE-coated sample indicated a much better surface, devoid of plowing marks and material adhesions that existed on the uncoated carbide. The smoothness of the worn surface suggests that the MoS2/PTFE coatings acted as an effective lubricant during the friction test, preventing the direct metal-to-metal contact between the carbide and the counterpart ball [29,30]. It was also observed that the wear area width was about 55 μm for the coated carbide, compared to only 45 μm for the uncoated carbide at the load of 80 N, which was increased by approximately 22%. The increase in wear scar width can be attributed primarily to the lower shear strength and surface hardness of the coatings. Despite this, the MoS2/PTFE coatings, due to their greater thickness, maintained continuous and stable lubrication throughout the friction process, and the substrate experienced virtually no wear under the same testing conditions.
The enlarged micrographs and EDS images in Figure 9b–d revealed that a significant portion of MoS2/PTFE coatings was kept intact. This confirms that the MoS2/PTFE coatings were effective in maintaining their lubricating properties during the friction process, which helped to reduce the friction. In contrast, it was clear that some portion of the coating had worn off. Moreover, the SEM micrographs revealed coating peeling and delamination on the worn surface, a direct consequence of the mechanical stresses and wear by the frictional interaction. This phenomenon is common in coatings that provide lubrication but are subject to mechanical degradation under extreme wear conditions [30,31].

3.4. Discussion

The test demonstrates that MoS2/PTFE coatings can enhance the performance of carbide by reducing friction and wear. For the traditional sample, the counter ball directly interacts with the carbide. The direct contact results in a higher shear force of the surface, which leads to the increase of friction coefficient, as observed in Figure 6 and Figure 7. The friction behavior of the uncoated carbide is primarily driven by this substantial interfacial shear, which requires overcoming a significant resistance at the contact surface [31]. Consequently, this results in higher friction and wear.
In contrast, the carbide coated with MoS2/PTFE coatings exhibits an improvement in friction behavior. The MoS2/PTFE coatings significantly reduce the shear force between the sliding surfaces, which directly reduces the friction coefficient. Figure 6 and Figure 7 clearly demonstrate that the MoS2/PTFE-coated carbide shows a consistently lower and more stable friction coefficient. The carbide serves as a strong support for the MoS2/PTFE coatings, ensuring that the lubricating property remains effective throughout the experiment. This coating helps to protect the carbide’s surface from excessive wear and adhesion, leading to a noticeable enhancement in both the friction and wear properties.
Furthermore, the test highlights the importance of the applied load in influencing the tribological performance of carbide. As the applied load increases, the friction coefficient of the uncoated carbide gradually decreases, which is in accordance with the Hertzian contact theory [31]. However, for the MoS2/PTFE-coated carbide, the friction coefficient remains relatively steady and consistently low, irrespective of the varying test conditions or applied load. This indicates that the MoS2/PTFE coatings help maintain a stable and efficient frictional behavior.
In addition to its effect on friction, the MoS2/PTFE coatings can also decrease surface adhesion and plowing. The uncoated carbide, as shown in Figure 8, displays clear mechanical scratches and adhesion. This adhesion occurs as a result of the repeated contact between the surfaces. The mechanical plowing and adhesion contribute to a rougher surface.
On the other hand, the MoS2/PTFE-coated carbide exhibits reduced mechanical plowing and adhesion and increased surface wear (Figure 9). The coatings significantly reduce the material transfer and maintain a more uniform, continuous, and stable lubrication during the friction process due to the higher thickness. Meanwhile, the stable lubrication also contributes to the stability of the friction coefficient, as presented in Figure 6 and Figure 7.
A future investigation will be carried out on the influence of different components of coatings and test conditions, such as test duration, sliding speed, roughness, and temperature.

4. Conclusions

The MoS2/PTFE coatings were prepared on cemented carbide using spray technology. This study mainly aimed to measure and compare the primary properties of MoS2/PTFE-coated cemented carbide with an uncoated one. The findings are as follows:
(1)
MoS2/PTFE coatings were uniform and dense. The adhesion strength between MoS2/PTFE coatings and the substrate was up to 36 N. The hardness was about 0.42 GPa, the thickness was about 13 μm, and the surface roughness was about 0.36 μm.
(2)
MoS2/PTFE coatings significantly reduce the shear force between the sliding surfaces, which directly reduces the friction coefficient of carbide. The coatings help maintain a relatively steady and consistently low friction coefficient, irrespective of the varying test conditions.
(3)
MoS2/PTFE coatings can decrease surface adhesion and plowing and maintain a more uniform, continuous, and stable lubrication during the friction process due to the higher thickness. The results indicate the effect of MoS2/PTFE coatings in improving the friction property and the service life of cemented carbide, particularly in applications that involve dry sliding or abrasive contact.

Author Contributions

L.Z. and W.S. conceived, designed, and performed the experiment; W.S. analyzed the data; W.S. and L.Z. wrote the paper. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Key Research and Development Program of Jining, China (2022HHCG014), the Science and Technology Innovation Team Foundation of Jining University (23KCTD07), and the Scientific Research Foundation of Jining University (2022HHKJ02, 2023HHKJ04).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The original contributions presented in this study are included in the article, and further inquiries can be directed to the corresponding author.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Chen, Y.H.; Wang, J.; Chen, M. Enhancing the machining performance by cutting tool surface modifications: A focused review. Mach. Sci. Technol. 2019, 23, 477–509. [Google Scholar] [CrossRef]
  2. Sandoval, J.; Ali, A.; Kwon, P.; Stephenson, D.; Yang, G. Wear reduction mechanisms in modulated turning of compacted graphite iron with coated carbide tool. Tribol. Int. 2023, 178, 108062. [Google Scholar] [CrossRef]
  3. Koricherla, M.V.; Torgerson, T.B.; Alidokht, S.A.; Munagala, V.N.V.; Scharf, T.W. High temperature sliding wear behavior and mechanisms of cold-sprayed Ti and Ti-TiC composite coatings. Wear 2021, 476, 203746. [Google Scholar] [CrossRef]
  4. Boyle, H.; Norgren, S.; Crawforth, P.; Christofidou, K.; Boing, D.; Jackson, M. Insights in α-Al2O3 degradation in multilayer CVD coated carbide tools when turning IN718. Wear 2023, 523, 204786. [Google Scholar] [CrossRef]
  5. Bjerke, A.; Lenrick, F.; Hrechuk, A.; Slipchenko, K.; M’Saoubi, R.; Andersson, J.M.; Bushlya, V. On chemical interactions between an inclusion engineered stainless steel (316L) and (Ti,Al)N coated tools during turning. Wear 2023, 532–533, 205093. [Google Scholar] [CrossRef]
  6. Saikaew, C.; Paengchit, P.; Wisitsoraat, A. Machining performances of TiN+AlCrN coated WC and Al2O3+TiC inserts for turning of AISI 4140 steel under dry condition. J. Manuf. Process 2020, 50, 412–420. [Google Scholar] [CrossRef]
  7. Jackson, M.J.; Robinson, G.M.; Whitt, M.D.; Silva, R.B.; Silva, M.B.; Machado, A.R. Achieving clean production with nanostructured coated milling tools dry machining low carbon steel. J. Clean. Prod. 2023, 422, 138523. [Google Scholar] [CrossRef]
  8. Olsson, M.; Bushlya, V.; Lenrick, F.; Ståhl, J.E. Evaluation of tool wear mechanisms and tool performance in machining single-phase tungsten. Int. J. Refract. Met. Hard Mater. 2021, 94, 105379. [Google Scholar] [CrossRef]
  9. Roushan, A.; Rao, U.S.; Sahoo, P.; Patra, K.; Rawat, S.S. Wear behavior of AlTiN coated WC tools in micromilling of Ti6Al4V alloy using vegetable oil-based nanofluids. Tribol. Int. 2023, 188, 108825. [Google Scholar] [CrossRef]
  10. Kumar, C.S.; Urbikain, G.; Fernandes, F.; Rjoub, A.A.; Lacalle, L.N.L.D. Influence of V concentration in TiAlSiVN coating on self-lubrication, friction and tool wear during two-pass dry turning of austenitic steel 316L. Tribol. Int. 2024, 193, 109355. [Google Scholar] [CrossRef]
  11. Li, Y.T.; Xie, M.L.; Sun, Q.; Xu, X.J.; Fan, X.Q.; Zhang, G.A.; Li, H.; Zhu, M.H. The effect of atmosphere on the tribological behavior of magnetron sputtered MoS2 coatings. Surf. Coat. Technol. 2020, 378, 125081. [Google Scholar] [CrossRef]
  12. Sun, J.; Deng, J.X.; Li, X.M.; Meng, Y.; Zhang, Y.; Zhang, L.L.; Lu, Y. Preparation and tribological properties of MoS2-based multiple-layer structured films fabricated by electrohydrodynamic jet deposition. Surf. Coat. Technol. 2020, 384, 125334. [Google Scholar] [CrossRef]
  13. Mukhtar, S.H.; Wani, M.F.; Sehgal, R.; Sharma, M.D. Nano-mechanical and nano-tribological characterisation of self-lubricating MoS2 nano-structured coating for space applications. Tribol. Int. 2023, 178, 108017. [Google Scholar] [CrossRef]
  14. Lian, Y.S.; Long, Y.Y.; Zhao, G.L.; Mu, C.L.; Li, X.M.; Deng, J.X.; Xie, C.P. Performance of CrCN-WS2 hard/soft composite coated tools in dry cutting of titanium alloys. J. Manuf. Process 2020, 54, 201–209. [Google Scholar] [CrossRef]
  15. Abdelrazek, A.H.; Choudhury, I.A.; Nukman, Y.; Kazi, S.N. Metal cutting lubricants and cutting tools: A review on the performance improvement and sustainability assessment. Int. J. Adv. Manuf. Technol. 2020, 106, 4221–4245. [Google Scholar] [CrossRef]
  16. Saravanan, P.; Selyanchyn, R.; Watanabe, M.; Fujikawa, S.; Tanaka, H.; Lyth, S.M.; Sugimura, J. Ultra-low friction of polyethylenimine/molybdenum disulfide (PEI/MoS2)15 thin films in dry nitrogen atmosphere and the effect of heat treatment. Tribol. Int. 2018, 127, 255–263. [Google Scholar] [CrossRef]
  17. Xing, Y.Q.; Wu, Z.; Yang, J.J.; Wang, X.S.; Liu, L. LIPSS combined with ALD MoS2 nano-coatings for enhancing surface friction and hydrophobic performances. Surf. Coat. Technol. 2020, 385, 125396. [Google Scholar] [CrossRef]
  18. Pitenis, A.A.; Ewin, J.J.; Harris, K.L.; Sawyer, W.G.; Krick, B.A. In vacuo tribological behavior of polytetrafluoroethylene (PTFE) and alumina nanocomposites: The importance of water for ultralow wear. Tribol. Lett. 2014, 53, 189–197. [Google Scholar] [CrossRef]
  19. Wang, Y.; Zhao, Y.L.; Darutc, G.; Poirier, T.; Stella, J.; Wang, K.; Liao, H.L.; Planchece, M.P. A novel structured suspension plasma sprayed YSZ-PTFE composite coating with tribological performance improvement. Surf. Coat. Technol. 2019, 358, 108–113. [Google Scholar] [CrossRef]
  20. Zhang, Y.P.; Li, P.P.; Ji, L.; Wan, H.Q.; Chen, L.; Li, H.X.; Jin, Z.L. Tribological properties of MoS2 coating for ultra-long wear-life and low coefficient of friction combined with additive g-C3N4 in air. Friction 2021, 9, 789–801. [Google Scholar] [CrossRef]
  21. Peng, S.G.; Zhang, L.; Xie, G.X.; Guo, Y.; Si, L.N.; Luo, J.B. Friction and wear behavior of PTFE coatings modified with poly (methyl methacrylate). Compos. Part B Eng. 2019, 172, 316–322. [Google Scholar] [CrossRef]
  22. Mukhtar, S.H.; Gulzar, A.; Saleem, S. Advances in development of solid lubricating MoS2 coatings for space applications: A review of modeling and experimental approaches. Tribol. Int. 2024, 192, 109194. [Google Scholar] [CrossRef]
  23. Bashandeh, K.; Lan, P.X.; Meyer, J.L.; Polycarpou, A.A. Tribological performance of graphene and PTFE solid lubricants for polymer coatings at elevated temperatures. Tribol. Lett. 2019, 67, 99. [Google Scholar] [CrossRef]
  24. Lu, Y.; Deng, J.X.; Song, W.L.; Li, X.M.; Zhang, L.L.; Sun, J. Tribological performance of AlCrN-MoS2/PTFE hard-lubricant composite coatings. Proc. Inst. Mech. Eng. Part J J. Eng. Tribol. 2020, 234, 1355–1367. [Google Scholar] [CrossRef]
  25. Voevodin, A.A.; Zabinski, J.S. Nanocomposite and nanostructured tribological materials for space applications. Compos. Sci. Technol. 2005, 65, 741–748. [Google Scholar] [CrossRef]
  26. Chen, S.S.; Chen, S.Y.; Lan, J.L.; Qin, H.X.; Yang, S.; Wang, P.; You, Y. Core-shell structure polydopamine and polyethylenimine co-assisted MoS2-BaTiO3/polyarylene ether nitrile nanocomposites for high-temperature resistant organic dielectrics. J. Alloys Compd. 2024, 977, 173336. [Google Scholar] [CrossRef]
  27. Song, W.L.; An, L.; Lu, Y.; Zhang, X.; Wang, S.J. Friction behavior of TiN-MoS2/PTFE composite coatings in dry sliding against SiC. Ceram. Int. 2021, 47, 24003–24011. [Google Scholar] [CrossRef]
  28. Espallargas, N.; Vitoux, L.; Armada, S. The wear and lubrication performance of liquid-solid self-lubricated coatings. Surf. Coat. Technol. 2013, 235, 342–353. [Google Scholar] [CrossRef]
  29. Song, W.L.; Xia, Z.X.; Wang, S.J.; Zhang, Q.G. Effect of Zr target current on the mechanical and tribological performance of MoS2-Zr composite lubricating coatings. Coatings 2020, 10, 80. [Google Scholar] [CrossRef]
  30. Song, W.L.; Wang, S.J.; Lu, Y.; An, L.; Zhang, Q.G. Tribological performance of DLC-coated ceramics against cemented carbide under dry sliding conditions. Ceram. Int. 2021, 47, 16926–16934. [Google Scholar] [CrossRef]
  31. Wen, S.Z. Principle of Tribology; Tinghua University Press: Beijing, China, 2017. [Google Scholar]
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Figure 1. SEM micrographs (a,b) and element analyses of points A–C (c–e) of (b) of MoS2/PTFE coatings.
Figure 1. SEM micrographs (a,b) and element analyses of points A–C (c–e) of (b) of MoS2/PTFE coatings.
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Figure 2. Cross-section micrographs (a,b) of coated carbide.
Figure 2. Cross-section micrographs (a,b) of coated carbide.
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Figure 3. Three-dimensional topography of uncoated (a) and coated (b) carbides.
Figure 3. Three-dimensional topography of uncoated (a) and coated (b) carbides.
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Figure 4. Scratch curve of the coated carbide.
Figure 4. Scratch curve of the coated carbide.
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Figure 5. Scratch micrographs (a–c) and element analyses of points A–C (d–f) in (b,c).
Figure 5. Scratch micrographs (a–c) and element analyses of points A–C (d–f) in (b,c).
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Figure 6. Friction coefficient curves under different loads (speed = 8 mm/s, sliding time = 15 min): (a) 20 N; (b) 40 N; (c) 60 N; (d) 80 N.
Figure 6. Friction coefficient curves under different loads (speed = 8 mm/s, sliding time = 15 min): (a) 20 N; (b) 40 N; (c) 60 N; (d) 80 N.
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Figure 7. Friction coefficient curves under different speeds (load = 60 N, sliding time = 15 min): (a) 4 mm/s; (b) 6 mm/s; (c) 8 mm/s; (d) 10 mm/s.
Figure 7. Friction coefficient curves under different speeds (load = 60 N, sliding time = 15 min): (a) 4 mm/s; (b) 6 mm/s; (c) 8 mm/s; (d) 10 mm/s.
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Figure 8. SEM micrographs (a,b) and element analyses in points A and B (c,d) of the uncoated carbide (load = 80 N, speed = 8 mm/s, sliding time = 15 min).
Figure 8. SEM micrographs (a,b) and element analyses in points A and B (c,d) of the uncoated carbide (load = 80 N, speed = 8 mm/s, sliding time = 15 min).
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Figure 9. SEM micrographs (a,b) and element analyses in points A and B (c,d) of the coated carbide (load = 80 N, speed = 8 mm/s, sliding time = 15 min).
Figure 9. SEM micrographs (a,b) and element analyses in points A and B (c,d) of the coated carbide (load = 80 N, speed = 8 mm/s, sliding time = 15 min).
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Table 1. Performance of cemented carbide.
Table 1. Performance of cemented carbide.
Composition
(wt.%)		Density
(g/cm3)		Size
(mm)		Flexural Strength (MPa)Young’s
Modulus (GPa)		Hardness (GPa)
WC + 15%TiC + 6%Co11.6516 × 16 × 5 124549816.2
Table 2. Performance of MoS2/PTFE coatings.
Table 2. Performance of MoS2/PTFE coatings.
Microhardness (GPa)Coating Thickness (μm)Adhesion Force (N)Roughness (μm)
0.42 ± 0.0513 ± 0.236 ± 20.36 ± 0.03
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Zhang, L.; Song, W. Friction Behavior of Molybdenum Disulfide/Polytetrafluoroethylene-Coated Cemented Carbide Fabricated with a Spray Technique in Dry Friction Conditions. Coatings 2025, 15, 324. https://doi.org/10.3390/coatings15030324

AMA Style

Zhang L, Song W. Friction Behavior of Molybdenum Disulfide/Polytetrafluoroethylene-Coated Cemented Carbide Fabricated with a Spray Technique in Dry Friction Conditions. Coatings. 2025; 15(3):324. https://doi.org/10.3390/coatings15030324

Chicago/Turabian Style

Zhang, Li, and Wenlong Song. 2025. "Friction Behavior of Molybdenum Disulfide/Polytetrafluoroethylene-Coated Cemented Carbide Fabricated with a Spray Technique in Dry Friction Conditions" Coatings 15, no. 3: 324. https://doi.org/10.3390/coatings15030324

APA Style

Zhang, L., & Song, W. (2025). Friction Behavior of Molybdenum Disulfide/Polytetrafluoroethylene-Coated Cemented Carbide Fabricated with a Spray Technique in Dry Friction Conditions. Coatings, 15(3), 324. https://doi.org/10.3390/coatings15030324

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