Research

20 pages, 26455 KiB

Open AccessEditor’s ChoiceArticle

Comparison of Various Conversion Layers for Improved Friction Performance of Railway Wheel-End Bearings

by Esteban Broitman, Arnaud Ruellan, Ralph Meeuwenoord, Daan Nijboer and Victor Brizmer

Coatings 2023, 13(12), 1980; https://doi.org/10.3390/coatings13121980 - 21 Nov 2023

Viewed by 842

With a growing global railway market which needs to reduce its energy consumption and emissions, railway wheel-end bearing units are being optimized to further reduce power losses with no compromise on reliability. One of the different solutions being evaluated is the selection of [...] Read more.

With a growing global railway market which needs to reduce its energy consumption and emissions, railway wheel-end bearing units are being optimized to further reduce power losses with no compromise on reliability. One of the different solutions being evaluated is the selection of the optimum surface engineering. Inner and outer rings of railway bearing units are currently coated with a zinc-calcium phosphate conversion coating designed for anti-corrosion, anti-fretting, and mounting properties. In this study, different conversion layers, like zinc-calcium phosphate, manganese-phosphate and tribological black oxide, have been compared in terms of friction performance using a single-contact tribometer and a grease-lubricated bearing friction test rig. Results demonstrate that an optimum tribological black oxide conversion layer can reduce the bearing torque by up to 30% in both low and intermediate speeds relevant to intercity trains. Full article

(This article belongs to the Special Issue Surface Engineering, Coatings and Tribology)

► Show Figures

Figure 1

29 pages, 15454 KiB

Open AccessArticle

Friction Coefficient Dynamics of Tribological Coatings from Engine Lubricants: Analysis and Interpretation

by Saúl Domínguez García, Luis Béjar Gómez, Rafael Maya Yescas, Javier Lara Romero, Baltazar Castro Cedeño and Marco Antonio Espinosa Medina

Coatings 2023, 13(10), 1753; https://doi.org/10.3390/coatings13101753 - 11 Oct 2023

Viewed by 934

Abstract

Even today, there is no full understanding of the relationship between the physical, chemical, and mechanical properties and the behavior of the lubricating films formed in tribological systems. Most of the published scientific research measures and reports the overall values of friction and [...] Read more.

Even today, there is no full understanding of the relationship between the physical, chemical, and mechanical properties and the behavior of the lubricating films formed in tribological systems. Most of the published scientific research measures and reports the overall values of friction and wear, but the information given via statistical signals in the tribological tests is, in general, dismissed, leaving a hole in the study of the dynamics of tribological systems. In this work, an experimental study of statistical friction data, coating characteristics, and tribological performance is carried out using a pin-on-disk tribometer to test some metallic samples coated with lubricant films under several experimental conditions. The results indicate that long deposition times at high deposition temperatures of coatings from engine oil develop low-friction intervals, which fall until 20% of the uncoated coefficient friction. However, an unexpected and unfavorable behavior of the coatings was observed for the short deposition times and high temperature. In these conditions, the developed friction profiles reached a maximum level of friction that was 20% more than the uncoated coefficient friction. Moreover, it was found that the proper analysis and interpretation of the statistical data, in combination with the characterization of the coatings, describes the dynamics of the interactions between the bodies in contact and reveals the transitions of the surfaces with non-homogeneous properties throughout their depth. Full article

(This article belongs to the Special Issue Surface Engineering, Coatings and Tribology)

► Show Figures

Figure 1

20 pages, 5098 KiB

Open AccessArticle

Tribocorrosion Susceptibility and Cell Viability Study of 316L Stainless Steel and Ti6Al4V Titanium Alloy with and without DLC Coatings

by Ana Claudia Sene, Michely Glenda Pereira da Silva, Paulo Fabrício Macário, Angela Aparecida Vieira, Priscila Maria Sarmeiro Correa Marciano Leite, Newton Soares da Silva, Francisco Das Chagas Marques and Lúcia Vieira

Coatings 2023, 13(9), 1549; https://doi.org/10.3390/coatings13091549 - 04 Sep 2023

Viewed by 854

Abstract

Stainless steel (SS316L) and titanium alloy (Ti6Al4V) exhibit suitable properties for biomedical applications; however, the tribocorrosion of these materials, which is associated with metallosis, is still a significant concern. This work investigates the effectiveness of DLC smoothing coatings applied to the metals to [...] Read more.

Stainless steel (SS316L) and titanium alloy (Ti6Al4V) exhibit suitable properties for biomedical applications; however, the tribocorrosion of these materials, which is associated with metallosis, is still a significant concern. This work investigates the effectiveness of DLC smoothing coatings applied to the metals to reduce tribocorrosion and improve cell viability. The study was motivated by many reports of metallosis caused by metal debris in the soft tissues of the body. DLC coatings were produced using the plasma-enhanced chemical vapor deposition (PECVD) technique. The cytotoxicity, genotoxicity, and cell viability of metallic samples with and without DLC coatings were analyzed, considering the chemical composition of the coating and metallic components. The results show that the DLC coatings presented suitable interaction properties and no cytotoxicity or genotoxicity when exposed to the cellular environment, compared with the control group (p < 0.0001). They also demonstrated cell viability, low friction representing a reduction of 80%, and hardness 23–26 GPa, making them ideal for use on fixed implants. It is necessary to control the thickness and roughness of the coating to avoid pinholes and increase the corrosion protection of implants. These DLC coatings with low friction coefficients could facilitate the fixation of implantable pins and screws, including Kirschner wires. Full article

(This article belongs to the Special Issue Surface Engineering, Coatings and Tribology)

► Show Figures

Figure 1

22 pages, 6457 KiB

Open AccessArticle

Mechanical and Tribological Properties of the CrAl/CrAlN and CrAl/CrAlN-(a-CN_x) Multilayers Deposited by HIPIMS

by Cecilio J. Martínez-González, Max F. Flores-Jiménez, David I. Bravo-Barcenas, Omar Jiménez-Alemán and Martín Flores-Martínez

Coatings 2023, 13(8), 1344; https://doi.org/10.3390/coatings13081344 - 31 Jul 2023

Viewed by 1048

Abstract

In this study, two CrAl/CrAlN multilayer coatings of 1.5 µm and 1.2 µm thicknesses were deposited from a (50:50) CrAl sectioned target by high-power impulse magnetron sputtering (HIPIMS) onto A11 tool steel to evaluate the effect over mechanical and tribological properties by the [...] Read more.

In this study, two CrAl/CrAlN multilayer coatings of 1.5 µm and 1.2 µm thicknesses were deposited from a (50:50) CrAl sectioned target by high-power impulse magnetron sputtering (HIPIMS) onto A11 tool steel to evaluate the effect over mechanical and tribological properties by the addition of an (a-CNx) top layer. XRD analysis showed a CrAlN FCC structure (111) and a Cr phase (110). A glass-like morphology was observed in the CrAl layer and in the (a-CNx) top layer, while the CrAlN layers exhibited a columnar morphology according to the FE-SEM analysis. Raman analysis results confirmed characteristic peaks G and D for the carbon amorphous structure of the (a-CNx) top layer. Nanoindentation results showed comparable hardnesses (23.08 GPa ± 2.8 and 20.58 GPa ± 1.8) in both multilayer coatings. The CrAl/CrAlN multilayer with an (a-CNx) top layer increased the absorption energy capacity and the mechanical potential energy stored. The nano scratch test showed the strongest crack resistance and highest adhesive energy values for the CrAl/CrAlN multilayer. The addition of an (a-CNx) top layer improved the tribological behavior when higher normal loads were applied during the fretting test. Raman analysis showed an increase in the I(D)/I(G) ratio and a formation of a carbon sp² structure (i.e., graphite-like structure) over the worn surfaces, as well as dissipated energy (J/m) during the fretting test. Full article

(This article belongs to the Special Issue Surface Engineering, Coatings and Tribology)

► Show Figures

Figure 1

9 pages, 3324 KiB

Open AccessArticle

Correlation of Tensile Properties of Arc-Sprayed Coatings and Easy Testing Methods

by Abdelhek Idir, Rassim Younes, Mohand A. Bradai, Abdelhamid Sadeddine, Lidia Baiamonte and Giuseppe Pintaude

Coatings 2023, 13(5), 878; https://doi.org/10.3390/coatings13050878 - 07 May 2023

Cited by 2 | Viewed by 1042

Abstract

Different techniques are usually employed to evaluate the mechanical properties of arc-sprayed coatings. In many situations, comparing properties is complex, and values extracted from tensile tests are required for structural projects. X6CrNi18-8 stainless steel and molybdenum were sprayed onto a mild steel substrate [...] Read more.

Different techniques are usually employed to evaluate the mechanical properties of arc-sprayed coatings. In many situations, comparing properties is complex, and values extracted from tensile tests are required for structural projects. X6CrNi18-8 stainless steel and molybdenum were sprayed onto a mild steel substrate using the electric arc thermal spray technique to discuss this issue. After a detailed microstructure characterization, tensile tests were performed on both coatings to determine the yield strength and total elongation. Easy techniques were also applied: Vickers hardness and Charpy impact test. Tensile tests have shown that applying coatings increased the steel substrate’s total elongation. Molybdenum coating presented a higher impact resistance than the X6CrNi18-8 one, resulting in no correlation between elongation and Charpy values. On the other hand, correlations between hardness and yield strength were identified, opening a discussion on the effects of the microstructure and type of test used. Full article

(This article belongs to the Special Issue Surface Engineering, Coatings and Tribology)

► Show Figures

Figure 1

16 pages, 17332 KiB

Open AccessArticle

High-Temperature Erosion of SiC-NiCrAlY/Cr₃C₂-NiCr Coating

by Eduardo Enrique Velez Barragan, Marco Aurelio González Albarrán, Eduardo Rodríguez de Anda, Gabriel Israel Vásquez Guillen, José de Jesús Ibarra Montalvo, Juan Carlos Díaz Guillén and Jorge Manuel Chávez Aguilar

Coatings 2023, 13(4), 720; https://doi.org/10.3390/coatings13040720 - 31 Mar 2023

Viewed by 1085

Abstract

High-temperature erosion is a detrimental phenomenon in industries where particle flow exists, in which the search for new materials and mixes to increase the lifespan of mechanical components exposed to erosion is crucial. The present work studied the erosion resistance of two coatings [...] Read more.

High-temperature erosion is a detrimental phenomenon in industries where particle flow exists, in which the search for new materials and mixes to increase the lifespan of mechanical components exposed to erosion is crucial. The present work studied the erosion resistance of two coatings at 25 °C (RT) and 900 °C in a sandblast-type rig. The coatings were fabricated with cermet-type powders: (C1) commercial Cr₃C₂-NiCr and (C2) commercial Cr₃C₂-NiCr mixed with a laboratory-conditioned powder consisting of NiCrAlY (linking matrix) and SiC (ceramic phase). Both coatings were applied on an Incoloy 330 substrate using an HVOF thermal spray process. The C2 coating was 11% harder than C1 but had a 62.2% decrement in its K_IC value. The erosion test results at RT and 900 °C showed better erosion resistance on C1 than C2 at both testing temperatures and the three impact angles (30°, 60°, and 90°); this was attributed to the minor K_IC induced by SiC hard particles and the bigger propagation of inter-splat and trans-splat cracks in C2. The erosion mechanisms at RT and 900 °C were similar, but at high temperature, the apparent size of plastic deformation (micro-cutting, grooves, and craters) increased due to an increase in the matrix ductility. Maximum penetration depth always occurred at a 60° impact angle. Full article

(This article belongs to the Special Issue Surface Engineering, Coatings and Tribology)

► Show Figures

Figure 1

15 pages, 7234 KiB

Open AccessArticle

Microstructure and Mechanical Properties of Ti-TiH₂ Based Matrix Composites Reinforced with xTiB₂ Particles Processed by Powder Metallurgy

by David Israel Bravo Barcenas, Jorge Manuel Chávez Aguilar, Omar Jiménez Alemán, Luis Olmos Navarrete, Max Fernando Flores Jiménez, Marco Aurelio González Albarrán and Iván Gerardo Farias Velázquez

Coatings 2023, 13(3), 587; https://doi.org/10.3390/coatings13030587 - 09 Mar 2023

Cited by 2 | Viewed by 1303

Abstract

The structure changes, microstructure evolution, and mechanical properties during Powder Metallurgy (PM) through High Vacuum Sintering of a Ti-TiH₂ matrix reinforced with Titanium Diboride (TiB₂) particles were investigated. Composites were fabricated at 850, 1100, and 1300 °C. The strategy [...] Read more.

The structure changes, microstructure evolution, and mechanical properties during Powder Metallurgy (PM) through High Vacuum Sintering of a Ti-TiH₂ matrix reinforced with Titanium Diboride (TiB₂) particles were investigated. Composites were fabricated at 850, 1100, and 1300 °C. The strategy for the fabrication process was to use the PM route employing titanium hydride (TiH₂) to reduce the consumption of Commercially Pure Titanium (CP-Ti). The structure of the composites was analyzed using X-Ray Diffraction (XRD), while Optical Microscopy (OM), and Field-Emission Scanning Electron Microscopy (FE-SEM) analysis were used to study the microstructure. Vickers microhardness and nanoindentation were performed to evaluate the elastoplastic and mechanical properties. According to the results, the unreinforced Ti-TiH₂ sample presented higher sinter-ability, attaining relative density values of 93% with the higher sintering temperature. Composite samples showed TiB and TiB₂ phases without the presence of any TiH₂ residual phase. The highest mechanical properties were measured for reinforced samples with 30 vol.% of TiB₂, sintered at 1300 °C, showing values of 509.29 HV and 4.94 GPa for microindentation Vickers and nanoindentation essays, respectively, which resulted in 8.5% higher than the values for the unreinforced sample. In addition, their H/Er and H³/Er² ratios are higher than those of CP-Ti suggesting a better wear resistance of the Ti-TiH₂ matrix-reinforced samples, combined with its mechanical properties makes it more suitable than CP-Ti for its potential in biomedical applications. Full article

(This article belongs to the Special Issue Surface Engineering, Coatings and Tribology)

► Show Figures

Figure 1

18 pages, 6827 KiB

Open AccessArticle

Tribological Behaviour of Al-2024/TiC Metal Matrix Composites

by Egberto Bedolla-Becerril, Josefina Garcia-Guerra, Víctor H. Lopez-Morelos, Marco A. Garcia-Renteria, Lazaro A. Falcon-Franco, Víctor H. Martinez-Landeros, Sergio García-Villarreal and Sergio E. Flores-Villaseñor

Coatings 2023, 13(1), 77; https://doi.org/10.3390/coatings13010077 - 31 Dec 2022

Cited by 9 | Viewed by 1455

Abstract

Pin-on-disk tests were performed to evaluate the wear behaviour of a 2024 aluminium alloy metal matrix composite (MMC) reinforced with 52 vol.% of TiC particles (Al-2024/TiC) in a fabricated and thermal-treated (T6) condition. The MMC was produced via pressureless infiltration of partially sintered [...] Read more.

Pin-on-disk tests were performed to evaluate the wear behaviour of a 2024 aluminium alloy metal matrix composite (MMC) reinforced with 52 vol.% of TiC particles (Al-2024/TiC) in a fabricated and thermal-treated (T6) condition. The MMC was produced via pressureless infiltration of partially sintered TiC preforms with an average particle size of 1.1 μm at 1200 °C for 2 h under flowing argon. Microstructural and mechanical characterisation were carried out on both the monolithic alloy (MM) and the MMC with and without heat treatment. The effect of T6 heat treatment on the tribological behaviour of MMC has been investigated under dry sliding wear conditions under normal loads of 2, 5 and 10 N against ceramic α-Al₂O₃ and SAE 52100 steel spherical counterparts. Results indicate a substantial improvement in the microhardness (289–343 HV), hardness (25–34 HRC), and wear resistance of the MMC after T6 heat treatment (1 × 10⁻³ to 5 × 10⁻⁵ mm³/Nm). For a better understanding of the wear mechanisms, surfaces of the worn tracks were studied. Oxidation and abrasion were found as the dominant wear mechanisms in both MM and MMC samples. Even though MM exhibited a lower coefficient of friction (COF) (0.50–0.80), composites showed superior wear resistance by 5-fold higher than the base alloy. Full article

(This article belongs to the Special Issue Surface Engineering, Coatings and Tribology)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Surface Engineering, Coatings and Tribology

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Published Papers (8 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI