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Article

Fabrication and Tribology Properties of PTFE-Coated Cemented Carbide Under Dry Friction Conditions

by
Shoujun Wang
,
Wenlong Song
*,
Lei An
,
Zixiang Xia
and
Shengdong Zhang
School of Mechanical and Electrical Engineering, Jining University, Qufu 273155, China
*
Author to whom correspondence should be addressed.
Lubricants 2024, 12(11), 363; https://doi.org/10.3390/lubricants12110363
Submission received: 27 September 2024 / Revised: 21 October 2024 / Accepted: 22 October 2024 / Published: 23 October 2024
(This article belongs to the Special Issue Tribological Properties of Sprayed Coatings)
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Abstract

:
PTFE coatings were deposited on YT15 carbide substrates using spray technology. A series of examinations were conducted, including the use of surface and cross-section micrographs to analyze the structural integrity of the coatings. The surface roughness, the adhesion force between the PTFE coatings and the carbide substrate, and the micro-hardness of the coated carbide were also evaluated. Additionally, the friction and wear behaviors were assessed through dry sliding friction tests against WC/Co balls. The test results indicated that while the PTFE-coated carbide exhibited a rougher surface and reduced micro-hardness, it also demonstrated a significant reduction in surface friction and adhesive wear. These findings suggest that the PTFE coatings enhance the overall wear resistance of the carbides. The lower surface hardness and shear strength of the coatings influenced the friction performance, leading to specific wear failure mechanisms, such as abrasion wear, coating delamination, and flaking. Overall, the deposition of PTFE coatings on carbide substrates presents a promising strategy to enhance their friction and wear performance. This approach not only improves the durability of carbide materials but also offers potential applications in industries where reduced friction and wear are critical for performance.

1. Introduction

Due to the properties of high toughness, good hot hardness, and superior antiwear performance [1], cemented carbide has found extensive applications in various fields, including its use in machining tools, engine parts, sealing elements, and bearing components [1,2]. These remarkable characteristics make it a favored choice in demanding industrial environments. However, it is important to note that, in the absence of proper cooling and lubrication from cutting fluids, cemented carbide can exhibit relatively high friction, leading to serious adhesion issues and a significantly shortened operational lifetime [2]. This limitation poses a challenge for its use in sustained applications, highlighting the need for improved solutions.
One effective method to enhance the tribological performance of cemented carbide is through surface coating. Surface coatings can be categorized, based on their micro-hardness, into hard coatings and soft coatings. Hard coatings are characterized by their high surface hardness and strength, as well as their excellent wear resistance. These attributes make them particularly suitable for use in tough working environments, including dry machining, high-speed cutting, and mold stamping [3,4,5], where durability and performance are critical. The application of hard coatings has been widely studied and reported, showcasing their benefits in enhancing tool longevity and effectiveness [6,7,8,9,10].
Due to their inherently low shearing strength, soft coatings are particularly effective in minimizing the friction coefficient by forming a lubricating film between surfaces [11]. This phenomenon is crucial in various industrial applications, where reducing friction can lead to enhanced performance and durability. Several studies in the literature have explored the properties of soft coatings applied to cemented carbide, investigating materials such as Tungsten disulfide (WS2) [12,13,14,15], Molybdenum disulfide (MoS2) [16,17,18,19], and Strontium sulfate (SrSO4) [20]. These investigations have consistently demonstrated that the application of these coatings results in a significant reduction in both surface friction and the wear rate of the substrates. The effectiveness of these soft coatings in tribological applications highlights their potential for improving performance in demanding environments.
Among the diverse range of lubricating materials used in industrial applications, Polytetrafluoroethylene (PTFE) is a good choice. PTFE is celebrated for its excellent self-lubricating properties, coupled with good thermal and chemical stability [21,22]. These characteristics make PTFE an ideal candidate for soft coatings that aim to reduce surface friction and protect against adhesion wear, particularly in critical components found in aircraft and satellites [23,24,25]. PTFE coatings have been used to significantly extend the operational lifetime of substrates, as well as to enhance the adhesion and performance of transfer films on coated surfaces [26,27]. However, despite its widespread application, there has been a notable lack of comprehensive research focusing specifically on the tribological behavior of cemented carbide coated with PTFE. Therefore, a detailed investigation into the interactions and performance of PTFE-coated cemented carbide is essential to fully understand its potential benefits and applications in various engineering fields.
Soft coatings are primarily produced using methods like polishing coatings, physical vacuum deposition (PVD), and spraying techniques [12,13,14,15,16,17,18,19,20,21,22]. Burnished coatings often fail to deliver stable lubrication, primarily due to inadequate adhesion to the substrate, which limits their effectiveness in practical applications. PVD is a widely recognized method for depositing coatings; however, its low deposition rate and the limited thickness of the coating hinder its broader industrial adoption. In contrast, the spraying technique offers a promising alternative by significantly enhancing both the coating thickness and the preparation efficiency, making it a more viable option for industrial applications.
In the present study, the PTFE coatings using polyamide-imide (PAI) as a binder were deposited onto the surface of YT15 cemented carbide via spray technology. Property tests were conducted to assess the mechanical and physical properties of the PTFE coatings, also examining how these properties influenced the friction behavior of the cemented carbide substrate. This investigation aims to expand the industrial applicability of cemented carbide by demonstrating the potential benefits of these coatings in various environments.

2. Materials and Methods

2.1. PTFE Coating Preparation

In the present study, a widely used commercial YT15 cemented carbide from Zhuzhou Cemented Carbide Co., Ltd. (Zhuzhou, China). is selected as the substrate. The size of the cemented carbide is 16 mm × 16 mm × 5 mm, and the main composition and physical properties are listed in Table 1. Prior to applying the coatings, all samples underwent a degreasing and sandblasting process to enhance the bonding between the coating and substrate. These treatments are crucial for ensuring that the coatings adhere effectively, thereby improving their performance during use.
The PTFE powder, averaging 15–20 μm in size, was obtained from Daikin Fluorochemicals Co., Ltd. in China (Changsu, China). To ensure a homogenous mixture, the PTFE powder was mixed with the PAI binder and subjected to 40 min of stirring using a magnetic device, followed by 60 min of dispersion through ultrasonic means. The resulting mixture was then heated to 55 °C and applied to the cemented carbide at a pressure of 0.4 MPa using a spray gun. Subsequently, to ensure the optimal performance and durability of the PTFE coatings, the coated carbides were sintered at 400 °C for 25 min in an electric heating furnace. Finally, the samples were allowed to cool gradually within the furnace, which helps to stabilize the coatings and enhance their overall integrity. The key parameters for preparing the PTFE coatings are summarized in Table 2. Figure 1 provides the optical images of the uncoated sample and the coated sample.
For the evaluation of the adhesion force between the PTFE coatings and the carbide substrate, an MT-4000 material property tester, sourced from Lanzhou Instrument Technology Co., Ltd. in China (Lanzhou, China), was employed. This testing involved scratching a diamond stylus, with a radius of 0.2 mm, across the PTFE-coated surface. The scratch test was designed to include specific conditions to accurately assess adhesion force, including a travel distance of 8 mm, a force ranging from 0 to 60 N, and a controlled force with a variation rate of 100 N/min. Additionally, the surface micro-hardness of the coated sample was measured using an MH-6 micro-hardness meter from Shanghai Testing Instrument Co., Ltd. (Shanghai, China). The hardness test was conducted with an applied load of 0.2 N, providing valuable insights into the mechanical properties of the coating and its suitability for various applications.

2.2. Friction and Wear Tests

Due to their lower melting point and surface hardness, PTFE coatings were sensitive to test conditions such as temperature and load. Then, the tribology properties were measured using a ball-on-disk friction tester (China Jinan Hengxu Test Technology Co., Ltd., Jinan, China) under normal temperature conditions. In order to compare the properties of carbide, with and without coatings, a tungsten carbide–cobalt ball (WC + 6%Co), with a radius of 4.5 mm, was utilized. The sliding tests were conducted under a range of normal forces, varying from 20 to 80 N. The sliding velocity during the tests was maintained within the range of 4 to 10 mm/s, with a consistent stroke length of 6 mm and time of 15 min. To ensure the reliability and accuracy of the results obtained, all the results reported were the average values derived from three tests.
The worn surfaces of the samples were examined using a scanning electron microscope (SEM, INCA Penta FETXS, Oxford, UK) and energy dispersive spectroscopy (EDS, D8 ADVANCE, Bruker, Germany). This combination of SEM and EDX techniques enabled a thorough understanding of the wear mechanisms, which is beneficial for identifying the wear characteristics and the distribution of elements resulting from the tribological interactions during the sliding tests.

3. Results and Discussion

3.1. PTFE Coatings Properties

Figure 2 shows the SEM graphs and the energy-dispersive spectroscopy analyses conducted on the coated carbide. As displayed in Figure 2a–e, it is evident that PTFE coatings exhibit a surface that is relatively dense and stable overall. However, the carbide surface reveals itself to be somewhat irregular, showcasing a multitude of high and low peaks that contribute to a rather textured appearance. This texturing is further accentuated by the presence of noticeable micro-sized pores scattered across the coating’s surface, which could influence the surface roughness and smoothness of coating. From Figure 2e, it can be observed that the PTFE coatings possess a thickness of approximately 40 μm. The cross-sectional morphology of the internal coatings appears to be relatively homogeneous and well-compacted. Nevertheless, there are some issues such as delamination and spallation that are particularly prominent near the top surface of the coating. These defects likely occurred during the polishing process of the sample cross-section, attributed to the low hardness of the PTFE material, which makes it more susceptible to damage under mechanical stress. Importantly, it can be seen that despite these defects, the coatings maintain a strong bond with the substrate surface, exhibiting no serious delamination or cracking. Additionally, the fabrication method employed appears to have effectively limited the penetration of the coatings into the substrate, further preserving the integrity of the overall structure.
The surface topographies of both the uncoated and PTFE-coated samples were investigated using an optical profilometer, as depicted in Figure 3. The results of this analysis reveal a marked change in the characteristics of the surface. The roughness of the coated sample has increased significantly, reaching approximately Ra 495 nm. This represents an increase of about 55% when compared to the value of the uncoated substrate, which is only Ra 315 nm. This substantial increase in surface roughness could have implications for the performance and functional attributes of the coated samples, such as improved adhesion or altered wear properties.
The adhesion force between the PTFE coatings and the carbide substrates can be effectively evaluated by analyzing the variations in the friction force and the coefficient in relation to the loading force applied during scratch testing. Figure 4 illustrates the specific scratch test curve for coated carbide. Initially, during the scratch test, both the coefficient of friction and the slope of the friction force curve remained relatively stable at a low value. This stability indicates that the coating was performing effectively under minimal loading conditions. However, as the loading force exceeded 30 N, there was a notable and rapid increase in both the friction force and the friction coefficient. This abrupt rise can be attributed to the wear and degradation of the coatings as they began to lose their integrity under increasing mechanical stress. Once the loading force surpassed 40 N, the values of the friction force and the friction coefficient reached significantly higher levels, which indicated that the PTFE coatings had undergone complete wear and were no longer providing effective protection. Consequently, the adhesion force between the coatings and the carbide substrate can be estimated to be greater than 30 N. In comparison to the adhesion force values of other coating materials reported in author’s previous research, ranging from 45 N to 80 N, as documented in references [28,29], the adhesion force of the PTFE coatings was found to be relatively low. This reduced adhesive force can have significant implications for the lubrication capacity, resistance of wear, and overall service life of the coatings when subjected to higher loads.
To further validate the adhesion force, the SEM and EDS results of the scratch area are presented in Figure 5. From this figure, the scratch process can be distinctly divided into two phases. During the initial phase of the scratch test, prominent mechanical plowing was observed on the scratch track, indicating that the PTFE coatings were still intact, despite the application of force. This observation was corroborated by the EDS result at point A (Figure 5c), which confirmed the presence of the coating material on the scratch track. The existence of the coatings at this stage led to the smaller values for both the frictional force and the frictional coefficient, as illustrated in Figure 4. As the applied force continued to increase, the abrasive wear and spalling intensified, leading to progressive degradation of the coatings. Eventually, the underlying carbide substrate became exposed, as illustrated in Figure 5a,b. This exposure was further substantiated by the EDS result at point B (Figure 5d). Therefore, it follows that the rapid increase in both the frictional force and frictional coefficient during the test can be directly linked to the wear of the coatings. The SEM micrographs, along with the corresponding composition analysis results, align closely with the observed variations in the scratch curve presented in Figure 4, providing a comprehensive understanding of the scratch mechanisms.
Figure 6 illustrates the load-displacement curves of the nanoindentation tests on the PTFE-coated carbide. The indentation depth employed in these tests was significantly smaller than the overall coating thickness, which effectively avoided any potential influence from the underlying substrate material. The surface hardness of the PTFE-coated carbide was measured to be approximately 0.42 ± 0.05 GPa, which is very low when compared to that of the carbide substrate, which had a hardness of 16.5 ± 0.1 GPa. This disparity highlights the inherent differences in material properties and suggests that while the PTFE coatings may provide certain benefits in terms of lubrication and wear reduction, they do not significantly enhance the hardness of the composite structure when compared to that of the carbide substrate. This information is crucial for understanding the performance limitations of PTFE coatings in high-stress applications in which mechanical durability is paramount (Table 3).

3.2. Friction Properties of PTFE Coatings

Figure 7 illustrates the curves of the friction coefficient for two types of carbides under varying load conditions. From Figure 7, it is observed that there is a significant reduction in the friction coefficient for the coated carbide when compared to that of its uncoated counterparts under identical testing conditions. In the case of the traditional carbide samples, an observable increase in the friction coefficient was noted during the initial friction phase. This initial increase can be attributed to the gradual establishment of contact between the friction surfaces. Furthermore, the fluctuation in the friction coefficient was relatively minor during this period, largely attributed to the smooth surface characteristics of the friction pairs involved. However, as the experiment transitioned into the steady friction phase, the friction coefficient for the traditional carbides exhibited a gradual decrease, shifting from a range of 0.35–0.45 down to approximately 0.27–0.37 as the applied force gradually increased to 80 N. Additionally, during the steady state, there was a marked increase in the fluctuations observed in the friction curve. This increased fluctuation can be explained by the increased roughness resulting from the significant friction and wear processes occurring between the friction contact pairs. Conversely, for the PTFE-coated carbide, the frictional coefficient demonstrated superior stability and markedly less fluctuation during the entirety of the testing process. Notably, the friction coefficient for the coated carbide only showed a slight increase, from values of 0.09–0.12 to a range of 0.10–0.15 as the load increased, suggesting a more efficient performance under similar conditions.
In Figure 8, the curves of the friction coefficient for the samples tested at various sliding speeds are presented. It can be observed that they exhibit similarities to those shown in Figure 7, underscoring the consistency of the results across different testing parameters. It is noteworthy that the variation in test speed had less influence on the friction behaviors exhibited by the carbide samples. Specifically, when the friction speed was gradually elevated to 10 mm/s, the values of the friction coefficient for the uncoated carbides stabilized within a range of 0.25–0.35 during the steady friction phase. In contrast, the coated carbide demonstrated significantly smaller and more consistent values, maintaining friction coefficients around 0.08–0.15 throughout the process. These frictional tests indicate that the application of PTFE coatings on carbide substrates plays a crucial role in reducing surface friction, thereby enhancing the performance characteristics of the carbide materials. The findings suggest that not only do the coatings provide lower friction coefficients, but they also contribute to greater stability in regards to friction behavior across varying operational conditions.

3.3. Tribological Morphologies

To better assess the friction and wear properties of the uncoated carbide, a comprehensive examination of the worn sample was conducted using SEM and EDS after the 15 min sliding friction tests, as illustrated in Figure 9. From Figure 9, it can be observed that significant mechanical plowing, microcracks, and adhesions were evident on the worn surface of the carbide substrate. These mechanical plowing marks and microcracks, which are grooves formed due to the sliding action during friction, indicate the extent of the surface disruption. In addition, the presence of adhesions, which appeared as irregular deposits, suggested material transfer from the counter pair to the carbide surface.
The subsequent composition analysis, performed at points A and B, as depicted in Figure 9c,d, proved that the observed adhesion materials were composed primarily of WC and Co elements. These materials were not originally part of the carbide substrate but rather came from the WC ball, which highlights the interactive wear process occurring during the friction test. The serious adhesions formed during the friction process had a detrimental impact on the surface roughness of the uncoated sample. Increased roughness can lead to greater inconsistencies in the contact area between surfaces, resulting in fluctuations in the friction coefficient during testing, as shown in Figure 7 and Figure 8. These fluctuations can vary significantly, affecting the overall performance and stability of the carbide surface. Consequently, the primary wear modes identified for the uncoated carbide included adhesion wear, mechanical plowing, and microcracks. This wear process underscores the challenges faced by uncoated materials in frictional applications, where both mechanical and chemical interactions can lead to rapid degradation and reduced effectiveness over time.
Figure 10 presents the detailed micrographs and composition analyses of the worn surface for PTFE-coated carbide. The results illustrated in this figure highlight a significant difference between the worn surfaces of coated and uncoated samples. The coated carbide exhibited a distinctly smoother wear surface compared to that of the uncoated sample. This smoothness indicates effective lubrication, as there existed no obvious mechanical plow marks or adhesion materials on the worn surface of the coated specimen. Further examination through enlarged micrographs and composition analyses, as shown in Figure 10b–e, revealed that a considerable amount of the PTFE elements remained intact on the wear surface. This suggests that the PTFE coatings maintained their lubricating properties throughout the duration of the friction test, effectively contributing to reduced wear. However, it was also noted that some number of surface coatings had been worn away, as evidenced in Figure 10, which led to the obvious presence of carbide elements in the EDS analysis due to the reduced coating thickness. The phenomena of coating peeling and delamination were clearly observed on the worn surface, attributed to the wear and tear experienced between the interacting pairs. Consequently, it can be concluded that the primary wear modes affecting the coated sample involved the coating spalling and delamination.

3.4. Discussion

The results of the experiments clearly indicate that the surface coatings significantly enhanced carbide performance by minimizing friction and shielding the carbide substrate from adhesive wear under sliding friction conditions. In the case of traditional carbide, the counter WC ball engages directly with the carbide substrate during the sliding friction process. This interaction must overcome the high interfacial shear force between the two contact surfaces, which results in an increasing friction coefficient, as shown in Figure 7 and Figure 8. Conversely, the PTFE-coated carbide features a layer of coatings that significantly reduces shear strength compared to that of the underlying carbide substrate. The substrate, known for its superior mechanical properties, provides good support for the coatings. The coatings can effectively lubricate the contact surfaces, leading to a noticeable reduction in the friction coefficient and enhancing the anti-adhesive properties, as shown in Figure 7 and Figure 8. Furthermore, the applied force plays a crucial role in influencing the friction performance of traditional carbides; the friction coefficient tends to decrease gradually as the applied load increases, which aligns with the Hertz-contact theory [30]. On the contrary, the coefficient of friction for coated carbide remains a consistently smaller and more steady value under varying test conditions.
Additionally, the experimental findings demonstrate that PTFE coatings are remarkably effective at lowering the adhesion and mechanical plowing of the carbide surface. Notably, the uncoated sample displayed significant mechanical plowing and adhesion in the worn areas, which is proved by the SEM graphs and EDS analysis presented in Figure 9. The repeated adhesion and separation of material from the WC ball instigates friction and wear on the carbide surface, ultimately resulting in a rather rough surface. This observation correlates with the experimental results shown in Figure 7 and Figure 8, which illustrate significant fluctuations in the coefficient of friction for the uncoated carbide following the initial test phase. In contrast, the coated sample exhibited little mechanical plowing and adhesion on its worn track (Figure 10), leading to a smoother surface. The residual coating materials contributed to the stability of the friction coefficient for the coated carbide, as shown in Figure 7 and Figure 8. Furthermore, it is important to note that increasing the load can accelerate the wear and tear on the PTFE coatings due to their smaller shear force, adhesion strength, and coating hardness (Figure 10). However, thanks to the greater coating thickness (Figure 2), PTFE coatings maintained consistent and efficient lubrication throughout the sliding friction experiment. Consequently, it is evident that PTFE coatings significantly enhance the friction and wear behavior of the carbide substrate, providing a more reliable and effective solution for reducing wear in practical applications.

4. Conclusions

PTFE coatings were successfully fabricated on YT15 cemented carbide substrate utilizing spray technology. This study aimed to compare the mechanical properties and the friction and wear performance of the PTFE-coated samples with those of uncoated cemented carbide. The following conclusions are summarized, as follows:
(1)
The PTFE coatings demonstrated a uniform and dense structure. The coating adhesion force with the substrate was measured to be over 30 N, the hardness of the coated carbide was relatively low at just 0.42 GPa, the coating thickness was substantial at 40 μm, and the roughness of the surface was about 495 nm.
(2)
When comparing the frictional performance of the coated sample to that of its traditional uncoated counterparts, a significant reduction in the friction coefficient was observed, ranging from 65% to 75% under the same testing conditions. This substantial decrease in the friction coefficient is indicative of the enhanced lubricating properties of the PTFE coating. Furthermore, the coated sample exhibited the ability to maintain a small and steady friction coefficient under different sliding conditions.
(3)
The application of PTFE coatings resulted in a noticeable reduction in both adhesive wear and mechanical plowing on the carbide substrate. In terms of the wear mechanisms observed in the coated samples, coating delamination and flaking were identified as the primary modes. The reduced surface friction can be primarily attributed to the inherently smaller shear strength of the PTFE coatings, which allows for smoother sliding and minimizes the resistance encountered during friction tests. These results emphasize the effectiveness of PTFE coatings in enhancing the performance and durability of carbide substrates in various applications.

Author Contributions

W.S. and Z.X. conceived and designed the experiment; W.S. and S.W. performed the experiment; L.A., Z.X. and S.Z. analyzed the data; W.S. and S.W. 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).

Data Availability Statement

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

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. Optical images of the uncoated specimen (a) and the coated specimen (b).
Figure 1. Optical images of the uncoated specimen (a) and the coated specimen (b).
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Figure 2. SEM micrographs (a,b), EDS element analyses of points A (c) and B (d) in (b), and cross-section micrograph (e) of the coated specimen.
Figure 2. SEM micrographs (a,b), EDS element analyses of points A (c) and B (d) in (b), and cross-section micrograph (e) of the coated specimen.
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Figure 3. The 3D topographies of specimens without (a) and with coatings (b), obtained by a white light interferometer.
Figure 3. The 3D topographies of specimens without (a) and with coatings (b), obtained by a white light interferometer.
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Figure 4. Scratch curve of the coated specimen.
Figure 4. Scratch curve of the coated specimen.
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Figure 5. Scratch micrographs (a,b) and EDS element analysis results for points A (c) and B (d) in (a).
Figure 5. Scratch micrographs (a,b) and EDS element analysis results for points A (c) and B (d) in (a).
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Figure 6. Nanoindentation load-displacement curves of the PTFE-coated carbide.
Figure 6. Nanoindentation load-displacement curves of the PTFE-coated carbide.
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Figure 7. Friction coefficient curves under different loads during 15 min friction tests (sliding speed = 8 mm/s): (a) 20 N; (b) 40 N; (c) 60 N; (d) 80 N.
Figure 7. Friction coefficient curves under different loads during 15 min friction tests (sliding speed = 8 mm/s): (a) 20 N; (b) 40 N; (c) 60 N; (d) 80 N.
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Figure 8. Friction coefficient curves at different sliding speeds during 15 min friction tests (load = 60 N): (a) 4 mm/s; (b) 6 mm/s; (c) 8 mm/s; (d) 10 mm/s.
Figure 8. Friction coefficient curves at different sliding speeds during 15 min friction tests (load = 60 N): (a) 4 mm/s; (b) 6 mm/s; (c) 8 mm/s; (d) 10 mm/s.
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Figure 9. SEM micrographs (a,b) and EDS composition analysis at points A and B (c,d) in the worn surface for the uncoated specimen after the 15 min friction test (load = 60 N, sliding speed = 8 mm/s).
Figure 9. SEM micrographs (a,b) and EDS composition analysis at points A and B (c,d) in the worn surface for the uncoated specimen after the 15 min friction test (load = 60 N, sliding speed = 8 mm/s).
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Figure 10. SEM micrographs (a,b,e) and EDS composition analysis result for points A and B (c,d) in the worn surface for the coated specimen after the 15 min friction test (load = 60 N, sliding speed = 8 mm/s).
Figure 10. SEM micrographs (a,b,e) and EDS composition analysis result for points A and B (c,d) in the worn surface for the coated specimen after the 15 min friction test (load = 60 N, sliding speed = 8 mm/s).
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Table 1. Mechanical properties of cemented carbide.
Table 1. Mechanical properties of cemented carbide.
Composition
(wt. %)		Density
(g/cm3)		Hardness
(GPa)		Flexural Strength (MPa)Young′s
Modulus (GPa)		Thermal Expansion Coefficient (10−6/K)Poisson′s Ratio
WC + 15%TiC + 6%Co11.716.512305056.520.25
Table 2. Preparation parameters of PTFE coatings.
Table 2. Preparation parameters of PTFE coatings.
Magnetic Stirring Time (min)Ultrasonic Stirring (min)Spray Temperature (°C)Spray Pressure (MPa)Curing Temperature (°C)Curing Time (min)
4060550.440025
Table 3. Mechanical properties of the Cr coating.
Table 3. Mechanical properties of the Cr coating.
CoatingMicro-Hardness (GPa)Thickness (μm)Adhesion Strength (N)Roughness (nm)
PTFE0.42 ± 0.0540 ± 230 ± 3495 ± 5
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MDPI and ACS Style

Wang, S.; Song, W.; An, L.; Xia, Z.; Zhang, S. Fabrication and Tribology Properties of PTFE-Coated Cemented Carbide Under Dry Friction Conditions. Lubricants 2024, 12, 363. https://doi.org/10.3390/lubricants12110363

AMA Style

Wang S, Song W, An L, Xia Z, Zhang S. Fabrication and Tribology Properties of PTFE-Coated Cemented Carbide Under Dry Friction Conditions. Lubricants. 2024; 12(11):363. https://doi.org/10.3390/lubricants12110363

Chicago/Turabian Style

Wang, Shoujun, Wenlong Song, Lei An, Zixiang Xia, and Shengdong Zhang. 2024. "Fabrication and Tribology Properties of PTFE-Coated Cemented Carbide Under Dry Friction Conditions" Lubricants 12, no. 11: 363. https://doi.org/10.3390/lubricants12110363

APA Style

Wang, S., Song, W., An, L., Xia, Z., & Zhang, S. (2024). Fabrication and Tribology Properties of PTFE-Coated Cemented Carbide Under Dry Friction Conditions. Lubricants, 12(11), 363. https://doi.org/10.3390/lubricants12110363

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