Superior Wear Resistance Research Articles

Effect of SiC content on the microstructure and wear behavior of cold-sprayed Al-SiC coatings deposited on AZ31 alloy substrate

As a promising and recently developed deposition technique, cold spray deposition method is among the most recently implemented approaches to enhance the poor hardness and wear resistance of AZ31B magnesium alloy. This study investigated the effect of SiC content on the microstructural characteristics, microhardness, and wear behavior of cold-sprayed Al-(16, 28, and 38 wt%) SiC composite coatings. The incorporation of SiC particles into the Al-matrix coating led to the development of a mechanical interlocking mechanism and improved coating-substrate interfacial bonding. The microhardness of the Al-38 wt% SiC coating was approximately 80 % higher than that of the bare substrate due to reduced porosity and a uniform distribution of SiC particles. For coatings with higher SiC content, the dominant wear mechanism transitioned from adhesive to abrasive wear, as evidenced by the friction coefficient (COF) values and wear track micromorphology. The Al-16 wt% SiC coating exhibited the lowest COF and wear rate values, indicating superior wear resistance among the specimens.

Influence of droplet-free ta-C coatings and lubrication conditions on tribological performance and mechanical characteristics of WC−Co

Cemented carbide (WC−Co) tools suffer from surface abrasion, limiting their performance. This study explores droplet-free tetrahedral amorphous carbon (ta-C) coatings deposited via arc ion plating as a solution. The coatings possess a dense, sp3-rich structure, leading to a remarkable hardness of 60 GPa compared to 37 GPa of WC−Co, and strong adhesion with a critical scratch load of 41 N. Tribological tests confirm their effectiveness. Dry sliding tests show reduced wear and lower CoF (0.123) compared to uncoated tools (0.159). Notably, water-soluble lubricants yielded the best performance (lowest CoF: 0.092, superior wear resistance), while water and mineral oil also improved performance.

Tribo-informatics analysis of in-situ TiC reinforced ZA27 alloy: Microstructural insights and wear performance modeling by machine learning

The study examines the performance of ZA27 alloy reinforced with in-situ TiC under high-stress abrasive wear conditions. The ZA27 + 10 wt% TiC composite demonstrates superior wear resistance among all the materials tested. Response surface analysis revealed that increasing the applied load reduces the wear resistance of the specimens. Analysis of worn-out surfaces revealed mild grooves at low loads and deeper grooves at higher loads. The removal of material is mainly caused by ploughing and cutting actions from abrasive surfaces. Machine Learning models were employed to forecast wear rate, coefficient of friction, and temperature. The MLP model excelled, achieving an R² value of 0.88 during testing. Furthermore, feature importance analysis revealed that reinforcement wt% has the maximum influence in predicting the wear rate.

Wear-resistant enhanced composite coatings on TC4: Combining halide-activated pack cementation and plasma electrolytic oxidation

Enhancing the wear resistance is crucial to broadening titanium alloy application potential. In this study, we discovered that preparing a boron-infiltrated prefabricated coating using halide-activated pack cementation (HAPC) before plasma electrolytic oxidation (PEO) can significantly improve the wear resistance of TC4. The composite coatings (HAPC/PEO) produced through this method exhibit effective boron (B) penetration, with the main phase being H3BO3. We investigated the properties of HAPC/PEO and compared the wear resistance to a single PEO coating. Our results show that the hardness and modulus of elasticity of HAPC/PEO are enhanced, while its resistance to plastic deformation is increased and the coating is not easily damaged during friction. HAPC/PEO shows a 55 % decrease in the coefficient of friction and a 47 % reduction in wear rate compared to PEO coating, indicating superior wear resistance. We analyzed the stress distribution and displacement changes during friction between the PEO coating and HAPC/PEO using ABAQUS. The influence of the main phases' structure on the two coatings' wear resistance is also discussed, and the significant role of the laminated structure of H3BO3 in enhancing the wear resistance of HAPC/PEO was discovered.

Enhancing Wear Resistance of A390 Aluminum Alloy: A Comprehensive Evaluation of Thermal Sprayed WC, CrC, and Al2O3 Coatings

This study comparatively analyzed the wear characteristics and adhesion properties of 86WC–10Co–4Cr (WC) coatings deposited using the high velocity oxygen fuel process and 75Cr3C2–25NiCr (CrC) and Al2O3–3TiO2 (Al2O3) coatings deposited using the atmospheric plasma spray process on an A390 aluminum alloy substrate. The adhesion strength and wear test results demonstrated that the WC coating exhibited superior wear resistance. In contrast, the CrC and Al2O3 coatings showed lower adhesion properties and unstable frictional variations due to a higher number of defects compared to the WC coating. The WC coating layer, protected by WC particles, exhibited minimal damage and a low wear rate, followed by CrC and Al2O3. Ultimately, WC coating is highlighted as the optimal choice to enhance the wear resistance of A390 aluminum alloy.

Investigation of the Microstructure and Dry-Sliding Wear Behavior of Co Containing Al-Si-Fe Scrap Alloy

This study investigates the influence of cobalt (Co) addition on the microstructural and wear properties of an aluminum (Al) scrap alloy containing high iron (Fe) impurity content (3%). Microstructural analysis using scanning electron microscopy and optical microscopy confirmed the presence of Co in Fe-rich intermetallics. Upon increasing the Co concentration, β-Al5FeSi phase was seen to be refined without significant morphological modifications. Furthermore, Co addition promoted the formation of a new quaternary phase Al32Si7Fe4Co phase, which was finely distributed throughout the microstructure and acts as a tribo-layer in the Al scrap alloy, offering enhanced wear resistance and improved stability against wear. Standard EN-31 steel disk with compositions chromium (Cr)-1.6%, manganese (Mn)-0.75%, silicon (Si)-0.35%, and carbon (C)-0.9% was used for the wear test. Microhardness and wear properties were evaluated for both the as-cast and heat-treated alloys, with the as-cast samples exhibiting superior wear resistance and a lower coefficient of friction compared to the T6 heat-treated samples. Addition of Co showed refinement in the β-Fe rich intermetallics over the morphological modifications. Similarly, Co addition enhanced the hardness and wear resistance in the as cast alloys. This work provides a detailed analysis contributing significant understandings into the wear mechanisms and potential applications of Co modified recycled Al in various industrial sectors.

Ni-B-PTFE Nanocomposite Co-Deposition on the Surface of 2A12 Aluminum Alloy.

The spinning cup, a crucial component of textile equipment, relies heavily on 2A12 aluminum alloy as its primary raw material. Commonly, electroplating and chemical nickel-phosphorus (Ni-P) plating are employed to improve the surface characteristics of the object. Nevertheless, due to the growing expectations for the performance of aluminum alloys, the hardness and wear resistance of Ni-P coatings are no longer sufficient to fulfill industry standards. This study primarily focuses on the synthesis of Ni-B-PTFE nanocomposite chemical plating and its effectiveness when applied to the surface of 2A12 aluminum alloy. We examine the impact of the composition of the plating solution, process parameters, and various other factors on the pace at which the coating is deposited, the hardness of the surface, and other indicators of the coating. The research findings indicate that the composite co-deposited coating achieves its optimal surface morphology when the following conditions are met: a nickel chloride concentration of 30 g/L, an ethylenediamine concentration of 70 mL, a sodium borohydride concentration of 0.6 g/L, a sodium hydroxide concentration of 90 g/L, a lead nitrate concentration of 30 mL, a pH value of 12, a temperature of 90 °C, and a PTFE concentration of 10 mL/L. The coating exhibits consistency, density, a smooth surface, and an absence of noticeable pores or fissures. The composite co-deposited coating exhibits a surface hardness of 1109 HV0.1, which significantly surpasses the substrate's hardness of 232.38 HV0.1. The Ni-B-PTFE composite coating exhibits an average friction coefficient of around 0.12. It has a scratch width of 855.18 μm and a wear mass of 0.05 mg. This coating demonstrates superior wear resistance when compared to Ni-B coatings. The Ni-B-PTFE composite coating specimen exhibits a self-corrosion potential of -6.195 V and a corrosion current density of 7.81 × 10-7 A/cm2, which is the lowest recorded. This enhances its corrosion resistance compared to Ni-B coatings.

Wear and thermal coupled comparative analysis of additively manufactured and machined polymer gears

This study investigates the potential use of additive manufacturing (AM)-produced gears in the polymer gear industry as an alternative to conventionally manufactured gears. The focus is on comparing the wear and thermal properties of polyamide 6 (PA6) gears, the most commonly used in industry, with those of polyetherimide (PEI) gears manufactured via AM. The research aims to determine whether AM offers any advantages over conventional methods, particularly with regard to wear resistance and thermal performance. The wear behaviour of both types of gears is examined under various operating conditions, with particular attention being paid to the initial wear rates and how they evolve. PEI and PA6 test gears were evaluated using a custom-built gear wear test rig. Throughout the wear test, polymer test gears were subjected to wear by running against a metal gear. The gears were tested at various rotational speeds for up to 1 million cycles. During this process, measurements were taken to determine surface roughness changes, operational noise levels, microstructure analyses using scanning electron microscopy (SEM), and chemical structure analyses using Fourier transform infrared spectroscopy (FTIR). Additionally, thermal properties such as temperature generation and stability are monitored with a thermal camera and infrared thermometer to understand the suitability of each gear material for different applications. PA6 gears demonstrate better wear resistance at low and medium rotational speeds, while PEI gears show superior performance at high speeds. Furthermore, PEI gears display enhanced thermal properties, with lower temperature increases during operation compared to PA6 gears; this can be attributed to the porous structure inherent in AM, which allows for better heat dissipation. The findings suggest that AM-produced PEI gears hold promise as an important alternative in high-speed applications due to their superior wear resistance and thermal performance compared to conventionally manufactured PA6 gears.

Influence of heating temperature and time on mechanical-degradation, microstructures and corrosion performances of Teflon/granite coated aluminum alloys used for non-stick cookware

This study explores the functional characteristics (erosion, corrosion, mechanical damage, and microstructural features) of non-stick cookware made from aluminum alloys. Typically coated with polytetrafluoroethylene (PTFE-Teflon) or ceramic for non-stick properties, we conducted a systematic investigation using corrosion, abrasion, and mechanical tests on six types of cookware from different manufacturers (Manuf-1-6). The cookware was heated at various temperatures [Room temperature (RT), 100, 175, 250, & 350 °C] and times (45 & 120 min). Tests included Taber wear, Adhesive Pull-off, hot & RT corrosion, and surface roughness measurements. Characterization involved optical microscopy, scanning electron microscope (SEM) with electron backscattered diffraction (EBSD), and x-ray diffraction (XRD). Ceramic-coated cookware from Manuf-4 demonstrated superior mechanical strength, wear, and corrosion resistance due to refined microstructures. Manuf-1's PTFE-coated cookware also performed well. Optimal results were observed when heating below 250 °C for up to 45 min. Prolonged heating and temperatures beyond 250 °C adversely affected internal structures of all cookware. Thus, it is advisable to use Al-based non-stick cookware below 250 °C for a maximum of 45 min.

Influence of WC particle size and morphology on the performance of NiCu-based composite coatings deposited by laser direct energy deposition

NiCu alloys are commonly utilized due to their outstanding plasticity, toughness, corrosion resistance, and thermal conductivity. Nevertheless, their limited hardness and wear resistance have hindered their further development. In this study, 24CrNiMo alloy brake disc was coated with NiCu-based composite coatings containing different sizes and shapes of tungsten carbide, in order to investigate the effects of tungsten carbide particle characteristics on the microstructure, microhardness and wear resistance of Nickel‑copper composite coating. The results show that the microstructure of the coatings was minimally affected by the size and morphology of the WC particles, while non-spherical WC particles exhibited superior uniformity within the coatings. In terms of microhardness, smaller WC particles demonstrated a more consistent distribution. The ball-disk wear tests revealed that coatings with larger WC particles displayed better wear resistance in sizes, while those with non-spherical WC particles exhibited excellent resistance to wear in morphologies. Additionally, in abrasive wear tests, composite coatings containing spherical WC particles demonstrated superior wear resistance compared to those containing non-spherical WC particles. The diverse wear resistance observed in different wear experiments among the various WC coatings can be attributed primarily to differences in the distribution and preparation methods of the WC particles. Consequently, these findings hold significant promise for the practical application of NiCu-based composite coatings in industry.

Boosted wear and electrochemical corrosion resistance properties of Ti6Al4V alloy via graphene nanoplatelets and titanium particles

The Ti6Al4V(TC4) alloy is renowned for its robust strength, low density, exceptional resistance to corrosion, and outstanding biocompatibility, making it applicable in aviation, biomedical, and various other industries. However, its application is hindered by its inherent limited hardness and suboptimal resistance to wear. TiC, known for its compatibility with titanium alloys, serves as a frequently employed reinforcing phase in titanium matrix composites. The incorporation of TiC reinforcing phases can be classified into two categories: “in-situ” and “ex-situ”. In this research, graphene nanoplatelets (GNPs) and pure titanium (TA2) were ball-milled to produce graphene‑titanium particles, which were then utilized for the in-situ generation of TiC, and compared with the direct incorporation of nano-TiC into the titanium matrix. The deposition samples of GNPs/TA2/TC4 and nano-TiC/TA2/TC4 composites were fabricated employing the laser directed energy deposition technique. The findings of this research suggest that during the manufacturing process, the graphene nanoplatelets underwent dissolution within the molten pool. The carbon elements from the dissolved graphene nanoplatelets reacted in-situ with titanium elements, resulting in an ‘in-situ reaction’ that generated the TiC reinforcement phase. The microstructures of GNPs/TA2/TC4 and nano-TiC/TA2/TC4 deposition samples exhibit primary TiC in granular, floral, and dendritic morphologies. However, the TiC dendrites generated in situ by GNPs show shorter crystal axes. The GNPs/TA2/TC4 deposition sample displays the most pronounced grain refinement, featuring a mean grain size measuring 2.27 μm. The microhardness values of GNPs/TA2/TC4 and nano-TiC/TA2/TC4 deposition samples are (413 HV0.2 and 526 HV0.2), respectively, representing an increase of approximately 33 % and 69 % compared to the TA2/TC4 pure material deposition sample. The GNPs/TA2/TC4 deposition sample exhibits the lowest friction coefficient (0.236), indicating superior wear resistance. Moreover, the corrosion resistance of the GNPs/TA2/TC4 deposited sample is optimal (RP = 23,536 Ω cm2, Icorr = 2.03 × 10−6 A·cm−2, Ecorr = −0.703 V/SCE).

Computed Tomography Evaluation of Alumina Ceramic-on-Ceramic Total Hip Arthroplasty With More Than 20 years of Follow-Up: Is a Follow-Up Computed Tomography Scan Necessary?

BackgroundCeramic-on-ceramic (CoC) bearings have been increasingly used in total hip arthroplasty (THA) because of their superior wear resistance and biocompatibility. However, there is a scarcity of reports on the computed tomography (CT) evaluation of CoC bearings with more than 10 years. The aim of this study was to evaluate the long-term CT results of THA using CoC bearings for more than 20 years of follow-up. We hypothesized that there would be no wear, osteolysis, or ceramic fracture. MethodsBetween November 1997 and June 2003, 956 hips underwent THA using alumina-on-alumina bearings at a tertiary referral hospital. Among them, 107 hips were assessed, all of which underwent a CT examination more than 20 years after the index surgery. The mean age at the time of surgery was 41 years, and a CT scan was performed at an average of 22.0 years postoperatively (range, 20.0 to 25.1). The CT scans were thoroughly assessed for osteolysis, stem notching, and ceramic component fracture. ResultsNo loosening was observed in the acetabular cup or femoral stem. Stem notching was observed in 3 hips (2.8%). In the CT scan taken after a minimum of 20 years of follow-up, 1 case (0.9%) of osteolysis around the cup and 2 cases (1.9%) of osteolysis around the femoral stem were noted. Suspected chip fractures of the ceramic insert were discovered in 4 cases (3.7%). Despite these findings, the patients remained asymptomatic, and no subsequent surgical intervention was needed after close follow-up. ConclusionsRoutine CT examinations for patients who underwent THA using CoC bearings over 20 years ago revealed unexpected findings, such as osteolysis and suspected chip fractures of the ceramic liner. However, routine CT scans may not be universally necessary. The CT evaluation in this cohort should be selectively performed for patients who have relevant clinical symptoms. Level of evidenceLevel III, Therapeutic study.

Syncretic of soft, hard, and rigid segments cultivate high-performance elastomer

In materials science, achieving polymers that possess both high strength and high toughness—traditionally seen as contradictory properties—remains a significant challenge. In this study, a poly (urethane-imide-urea) (PUIU) was synthesized, featuring soft, hard, and rigid segment groups alternately distributed along the main chain. By integrating a polyurethane (PU) prepolymer, urea, and imide, with the PU prepolymer acting as the soft segment to confer malleability, urea-formed hydrogen bonds serving as the hard segment to provide toughness, and imide acting as the rigid segment to enhance material strength. The synergistic effects of these elements result in an elastomer with outstanding strength (70.1 ± 2.6 MPa), high elongation at break (1813.9 ± 76.0 %), and high toughness (420.4 ± 22.3 MJ/m3). Furthermore, it demonstrates superior fatigue, tear, and wear resistance. Through a blend of simulation and experimentation, we uncover the reasons behind its high performance. This study demonstrates the feasibility of preparing an elastomer that combines softness, hardness, and rigidity, meanwhile, achieving a balance between strength and toughness, thereby offering valuable theoretical guidance for the integration of high strength and high toughness.

Fabrication of amorphous AlMo0.5NbTa0.5TiZr RHEA coatings and the impact of deposition temperature on microstructure and properties

In this study, protective AlMo0.5NbTa0.5TiZr refractory high-entropy alloy coatings were prepared by DC magnetron sputtering, and the influence of deposition temperature on the microstructure, deposition rate, mechanical properties, and adhesion force was investigated in detail. All coatings are in a nearly amorphous state. Their elastic recovery ratio (ηw), microhardness (H), elastic strain failure strength (H/E), plastic deformation strength (H3/E2), and adhesion force (Lc2) are positively correlated with deposition temperature mainly attributing to the synergy of increased thickness and the generation of the nanocrystal. The coating reaches its maximum ηw, H, H/E, H3/E2, and Lc2 of 43.87 ± 0.94 %, 12.74 ± 0.37 GPa, 0.073 ± 0.002, and 0.067 ± 0.005 GPa at the deposition temperature of 500 °C and exhibits superior wear resistance and resistance to plastic deformation, compared with reported refractory Cr and α-Ta coatings.

Microstructure, property and high-temperature wear performance of Cr3C2-based coatings deposited by conventional and ID-HVAF spray torches: A comparative study

The durability of industrial components exposed to high temperatures can be increased by depositing high-velocity air-fuel (HVAF) sprayed Cr3C2-based coatings. The uniform embedding of wear-resistant Cr3C2 within an oxidation-resistant binder matrix allows HVAF-sprayed Cr3C2-based coatings to be widely used in high-temperature environments. However, consolidating these coatings demands an optimum particle velocity and temperature combination, primarily dependent on the spray torch design. Understanding the role of spray torch variants with altered combustion chamber and nozzle designs is essential, which might influence the coating (splat) formation mechanism and the resultant wear performance. Accordingly, Cr3C2–25NiCr and Cr3C2–30NiCrMoNb were sprayed using different HVAF torches (high-power AK06 and low-power AK05-ID (inner diameter): generate different energy (thermal + kinetic) output) to understand the role of the binder as well as the torch design. The deposited coatings were comprehensively compared based on splat morphology, microstructure, mechanical properties, room and high-temperature erosion and sliding wear behavior. Subsequently, a detailed post-wear analysis was performed to decipher the associated wear mechanism. As inferred from the results, Cr3C2–25NiCr coatings deposited through a high-power AK06 spray torch displayed preferable microstructure, properties and superior wear resistance. The study also offered new insights into HVAF-ID torch-deposited coatings.

Preparation and Performance Study of SiC-Reinforced Fe-Based Wear-Resistant Composite Grinding Media.

During industrial and laboratory processes involving material grinding, the grinding media endure prolonged high-collision and friction environments, resulting in substantial wear. Consequently, this study adopts the hot-pressing sintering technique in powder metallurgy to prepare SiC-reinforced Fe-based wear-resistant composite grinding media, aiming to increase wear performance. For this purpose, Fe with 10 wt% SiC powders were milled for the fabrication of the composite. Then, sintering was performed by hot press at 1100 °C in a furnace. Scanning electron microscopy (SEM) and X-ray diffraction were employed to investigate the microstructures and phase of SiC-reinforced Fe-based matrix composite. Subsequently, comparative performance evaluations of the newly developed grinding media and traditional chromium-based media were conducted in terms of wear rate and grinding efficiency. The wear resistance tests revealed that the SiC-reinforced composite media displayed significantly superior wear resistance across various abrasives compared to the chromium-containing alternatives. Specifically, the composite media achieved a wear rate reduction of 2.9 times against standard sand over 1 h, and 2.3 and 2.4 times against sandstone and iron slag, respectively. Moreover, extended grinding for 3 hours further enhanced these reductions to 3.1, 2.4, and 2.7 times, respectively. Additionally, efficiency assessments indicated that at a 1:1 material ratio, the composite media outperformed the chromium-containing media in grinding efficiency by 7.5%, 12.5%, and 10.3% for standard sand, sandstone, and iron slag, respectively. Further increasing the material ratio to 3:1 resulted in efficiency improvements of 7.4%, 17.5%, and 11.3%, correspondingly.

Enhancing Wear Resistance and Mechanical Behaviors of AA7020 Alloys Using Hybrid Fe3O4-GNP Reinforcement

This study investigates the effect of graphene nanoplatelets (GNPs) and milling duration on the microstructure, mechanical properties, and wear resistance of the AA7020 alloy reinforced with Fe3O4 and GNP. The composites were prepared with a fixed 10 wt.% Fe3O4 and varying GNP contents (0.5 and 1 wt.%) using high-energy ball milling for 4 and 8 h, followed by hot pressing. The aim was to enhance the performance of the AA7020 alloy for potential use in defense, automotive, aviation, and space applications, where superior mechanical properties and wear resistance are required. The results showed that the incorporation of 0.5 wt.% GNP and optimized milling significantly improved the composite’s performance. The AA7020 + 10 wt.% Fe3O4 + 0.5 wt.% GNP composite achieved the highest density (99.70%) when milled for 4 h. Its hardness increased with both the inclusion of GNP and extended milling duration, with the composite milled for 8 h exhibiting the highest hardness value (149 HBN). The tensile strength also improved, with the composite milled for 4 h showing a 28% increase (292 MPa) compared with the unreinforced alloy. Additionally, the friction coefficient decreased with GNP content and milling duration, with the composite milled for 8 h showing a 26% reduction. Wear resistance was notably enhanced, with the composite milled for 8 h exhibiting the lowest specific wear rate (7.86 × 10−7 mm3/Nm).

Optimization and high-temperature wear characterization of Stellite alloy claddings developed using TIG welding on 56NiCrMoV7 die steel

In this study, Stellite 6 and Stellite 12 claddings were deposited on 56NiCrMoV7 hot-worked die steel using the Tungsten Inert Gas (TIG) welding process. Initially, single tracks were deposited using a full factorial design varying two process parameters - current (65, 75, and 85 A) and scan speed (400, 600, and 800 mm/min). The single tracks were then optimized based on dilution rate and microhardness. The optimized parameters were used to develop Stellite 6 and 12 multi-pass clad layers on 56NiCrMoV7. The evaluation of the microstructure of the claddings was done using an optical microscope, XRD, FESEM, EDX, and EBSD. The microstructure of the claddings consists of α-Co matric with M7C3, M23C6, and W2C carbides precipitated along the grain boundaries. Further microhardness and tribological performance were analyzed using Vicker's hardness tester and ball-on-disc tribometer, respectively. Stellite 12 claddings exhibited superior wear resistance and indicated reduced wear volume by 51.3 % at room temperature, 69.2 % at 450 °C, and 32 % at 550 °C compared to the base material and 53.2 % at room temperature, 37.3 % at 450 °C, and 24.1 % at 550 °C compared to Stellite 6 claddings. The KAM mapping showed higher dislocation density for Stellite 12 cladding. The combination of finer grains, higher hardness, and higher dislocation density resulted in higher wear resistance.

Investigation on laser cladding Fe-based gradient coatings with hierarchical enhanced wear resistance on U75V railway steel

This study focused on the multilayer laser cladding of 15–5 precipitation hardening (PH) steel coating on U75V railway steel for improved surface performance. The effect of pearlitic substrate dilution action with high carbon content on microstructures and wear performance of PH steel coating with four deposited layers was investigated. Results showed that each cladding layer consisted of a similar multiphase mixture of martensite, retained austenite, and NbC carbides in the case of stepwise changes in chemical compositions induced by dilution effects. The wear resistance of the multilayered PH steel coating is closely related to the deposited layer number, reflected in a gradient increase in the wear rate with the increasing cladding layers. A comparative analysis against the U75V substrate showed substantial wear rate reductions of approximately 95 % and 4.5 % in the first and fourth layers, respectively. Besides, the cross-sectional microstructures were analyzed in detail to reveal the underlying friction-induced microstructural evolution of the gradient coating. The refinement of martensite laths controlled by dislocation reaction and the friction-induced austenite to martensite transformation was responsible for the superior wear resistance. The current experimental results could provide a new strategy for designing hierarchical enhanced wearable gradient coating for surface modification in railway components.

Facile design of PTFE-kaolin-based ternary nanocomposite as a hydrophobic and high corrosion-barrier coating

Abstract Superhydrophobic nanostructured coatings are a promising technology in construction engineering. This study developed a hydrophobic film through a simple mixing method, utilizing kaolin and polytetrafluoroethylene as additive particles, 1H,1H,2H,2H-perfluoro-decyl triethoxysilane as a modifier, and epoxide resin and polyamide curing agent as adhesives. By controlling variables, it was determined that the C1P0.2EP coating immersed in a 3.5 wt% NaCl solution for 1, 3, and 7 days exhibited the maximum impedance radii of 47,373, 20,334, and 1,982 Ω·cm2, respectively. It also demonstrated the highest Bode modulus values, the largest E corr, and the smallest I corr. Furthermore, after 300 h in a salt spray chamber with a 3.5 wt% NaCl solution, the C1P0.2EP coating showed no rust spots or bubbles, demonstrating its excellent corrosion resistance. Moreover, wear resistance tests and self-cleaning experiments were conducted on the C1P0.2EP coating. The results showed that after 100 friction cycles, the surface exhibited no visible scratches, and the contact angle of the coating decreased by only 4°. Additionally, neither soil particles nor dirty water adhered to the coating, indicating that the C1P0.2EP hydrophobic coating possesses not only excellent corrosion resistance but also superior wear resistance and self-cleaning capabilities.