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19 pages, 33776 KiB

Open AccessArticle

Properties of Diamond-like Tungsten-Doped Carbon Coatings Lubricated with Cutting Fluid

by Krystyna Radoń-Kobus, Monika Madej, Joanna Kowalczyk and Katarzyna Piotrowska

Coatings 2024, 14(3), 342; https://doi.org/10.3390/coatings14030342 - 13 Mar 2024

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In this paper, the authors investigated the impact of DLC coatings doped with tungsten (a-C:H:W) coatings obtained using plasma-assisted physical vapor deposition (PVD) on the properties of the 100Cr6 steel. The results of the 100Cr6 steel specimens with and without the coating were [...] Read more.

In this paper, the authors investigated the impact of DLC coatings doped with tungsten (a-C:H:W) coatings obtained using plasma-assisted physical vapor deposition (PVD) on the properties of the 100Cr6 steel. The results of the 100Cr6 steel specimens with and without the coating were compared. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis were used to observe the morphology of the coating surfaces and cross-sections and identify the elements in the coating composition. The contact angle of the investigated surfaces was measured with a tensiometer. Additionally, the effect of the coatings on the tribological properties of lubricated friction pairs was evaluated. Friction tests were performed on a ball-on-disc tribometer under lubrication with cutting fluid. The surface texture of the samples before and after the tribological tests was measured using a confocal profilometer. The results obtained from the tests and analysis allow for the conclusion that the use of DLC coatings a-C:H:W increases the hardness of 100Cr6 steel by three times. The values of the contact angles were indicative of surface hydrophilic characteristics. The tungsten-doped diamond-like coating under friction conditions reduced the coefficient of friction and wear. DLC coatings a-C:H:W lubricated with the cutting fluid improve the mechanical and tribological properties of 100Cr6 steel sliding surfaces under friction. Full article

(This article belongs to the Special Issue Advances in Deposition and Characterization of Hard Coatings)

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11 pages, 3358 KiB

Open AccessArticle

Investigation on Microstructure and Properties of Cold-Sprayed Ni-Mo-Al₂O₃ Composite Coating

by Yinqing Gong, Cong Xiao, Shunjie Hu, Yicheng Zhou, Chenglin Li, Bing Yang, Jianqiang Zhang and Guodong Zhang

Coatings 2024, 14(2), 205; https://doi.org/10.3390/coatings14020205 - 05 Feb 2024

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Abstract

In this work, the effect of Mo on the microstructure and properties of Ni-Mo-Al₂O₃ coatings by cold spraying was studied. The microstructure, composition, hardness, wear resistance and chlorine salt corrosion resistance of the coatings were analyzed by a scanning electron [...] Read more.

In this work, the effect of Mo on the microstructure and properties of Ni-Mo-Al₂O₃ coatings by cold spraying was studied. The microstructure, composition, hardness, wear resistance and chlorine salt corrosion resistance of the coatings were analyzed by a scanning electron microscope, EDS, X-ray diffractometer, 3D profilometer, microhardness tester and friction wear tester. The results show that the coatings have low porosity and a uniform structure. The addition of Mo can improve the hardness, electrical conductivity, wear resistance and chlorine salt corrosion resistance of the coating but reduce the deposition efficiency of the powder. In general, the 80Ni-10Mo-10Al₂O₃ coating has the best comprehensive performance, with a hardness of 270.17 HV, friction coefficient of 0.4171 and corrosion rate of 0.287 g/m²·h in molten chloride. Full article

(This article belongs to the Special Issue Advances in Deposition and Characterization of Hard Coatings)

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15 pages, 16308 KiB

Open AccessArticle

Tetrahedral Amorphous Carbon Coatings with Al Incorporation Deposited by a Hybrid Technique of Sputtering and Arc Evaporation

by Wei Dai, Yunzhan Shi, Qimin Wang and Junfeng Wang

Coatings 2024, 14(1), 142; https://doi.org/10.3390/coatings14010142 - 21 Jan 2024

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Abstract

In this paper, tetrahedral amorphous carbon (ta-C) coatings containing Al were deposited by a hybrid technique of sputtering and arc evaporation. The influence of Al incorporation in the structure and properties of the ta-C coatings were studied as a function of the Al [...] Read more.

In this paper, tetrahedral amorphous carbon (ta-C) coatings containing Al were deposited by a hybrid technique of sputtering and arc evaporation. The influence of Al incorporation in the structure and properties of the ta-C coatings were studied as a function of the Al concentration. It is found that Al tends to form a Al-O-C bond when the Al concentration is small. An Al-C bond was detected when the Al concentration is high. Al can facilitate the graphitization of the ta-C coatings and the graphite cluster size as well as the sp²/sp³ ratio of the coatings increase as the Al concentration increases. The decline of the sp³ fraction causes the drop in the hardness of the coatings. The incorporation of Al can effectively decrease the residual stress of the ta-C coatings. During friction tests, Al can facilitate the formation of the sp²-rich graphitic tribo-layer and decrease the friction coefficient. Nevertheless, the decline of the hardness due to the Al incorporation will result in the increase in the wear rate of the coating. It is believed that the ta-C coating with a proper concentration of Al appears to achieve a good comprehensive performance with high hardness, low residual stress, and a low friction coefficient and wear rate. Full article

(This article belongs to the Special Issue Advances in Deposition and Characterization of Hard Coatings)

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11 pages, 4427 KiB

Open AccessArticle

Replacing Toxic Hard Chrome Coatings: Exploring the Tribocorrosion Behaviour of Electroless Nickel-Boron Coatings

by Muslum Yunacti, Veronique Vitry, Alex Montagne and Mariana Henriette Staia

Coatings 2023, 13(12), 2046; https://doi.org/10.3390/coatings13122046 - 05 Dec 2023

Cited by 1 | Viewed by 796

Abstract

Electroless nickel-boron coatings present outstanding properties such as high hardness, excellent wear resistance and uniform coating, and thus they are considered to be alternative to toxic hard chrome coatings. However, they contain lead that is toxic and used as stabilizer in the plating [...] Read more.

Electroless nickel-boron coatings present outstanding properties such as high hardness, excellent wear resistance and uniform coating, and thus they are considered to be alternative to toxic hard chrome coatings. However, they contain lead that is toxic and used as stabilizer in the plating bath. This study aims to investigate the tribocorrosion behaviour of lead-free electroless nickel-boron coatings. In the present research, several tests were carried out to investigate the behaviour of these coatings under both dry and tribocorrosion reciprocating sliding wear against alumina balls, at room temperature. The open circuit potential (OCP) method was used to determine the degradation mechanism of the coatings. The results of the tribocorrosion and dry wear tests showed that the performance of coatings was very different from each other. A steady state for the coefficient of friction (COF) is achieved during the tribocorrosion test, whereas the constant production of debris and their presence in the contact implied an increase in COF with distance during the dry wear test. The wear mechanisms of these coatings also presented variations in these tests. It was found that the wear area calculated from tribocorrosion is lower (56 µm²) than the one from dry sliding test (86 µm²). Full article

(This article belongs to the Special Issue Advances in Deposition and Characterization of Hard Coatings)

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13 pages, 22917 KiB

Open AccessArticle

Microstructure and Properties of Inconel 718 Coatings with Different Laser Powers on the Surface of 316L Stainless Steel Substrate

by Yu Liu, Lin Zhu, Zeyu Li, Miao Yu, Yali Gao and Hui Liang

Coatings 2023, 13(11), 1947; https://doi.org/10.3390/coatings13111947 - 15 Nov 2023

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Abstract

Laser cladding is a new method to prepare coatings with good quality. Laser power is one of the main factors affecting the quality of laser cladding coatings. An appropriate laser power helps obtain a high-performance laser cladding coating. In order to obtain coatings [...] Read more.

Laser cladding is a new method to prepare coatings with good quality. Laser power is one of the main factors affecting the quality of laser cladding coatings. An appropriate laser power helps obtain a high-performance laser cladding coating. In order to obtain coatings with good quality, an experiment with different laser powers was designed in this research. Three Inconel 718 coatings with different laser powers were prepared on the surface of a 316L stainless steel substrate. And the effect of different laser powers (1400, 1600, and 1800 W) on the microstructure, phases, and element distribution of coatings (L1–L3) was investigated by SEM, EDS, XRD, and a wear and friction tester. Meanwhile, the microhardness and friction and wear properties of different coatings were analyzed. The results show that the coatings’ phases were the same and composed of γ~(Fe, Ni) solid solution, Ni₃Nb, (Nb_0.03Ti_0.97)Ni₃, MC_X (M = Cr, Nb, Mo), and so on. The background zones in the L1–L3 coatings were mainly the Fe and Ni elements. The irregular blocks in the coating were rich in Cr, Mo, and Nb, which formed the MC_X (M = Cr, Nb, Mo) phase. When laser powers were 1400, 1600, and 1800 W, the average microhardness of the three coatings was 685.6, 604.6, and 551.9 HV_0.2, respectively. The L1 coating had the maximum microhardness, 707.5 HV_0.2, because the MC_X (M = Cr, Nb, Mo)-reinforced phase appeared on the upper part of the coating. The wear rates were 3.65 × 10⁻⁵, 2.97 × 10⁻⁵, and 6.98 × 10⁻⁵ mm³·n⁻¹·m⁻¹. The wear mechanism of the three coatings was abrasive wear and adhesive wear. When the laser power was 1600 W, the coating had the minimum wear rate, which exhibited the best wear resistance. When the laser power was 1600 W, the upper part of the coating to the bonding zone was mainly composed of equiaxed crystals, dendrites, cellular crystals, columnar crystals, and planar crystals. The fine crystals and compounds caused a decrease in wear volume, and they had the most optimal wear resistance. Full article

(This article belongs to the Special Issue Advances in Deposition and Characterization of Hard Coatings)

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15 pages, 8377 KiB

Open AccessArticle

Preparation of Cold Sprayed Titanium TA2 Coating by Irregular Powder and Evaluation of Its Corrosion Resistance

by Zhengyi Li, Na Wang, Shuhua Li, Lei Wen, Chengcheng Xu and Dongbai Sun

Coatings 2023, 13(11), 1894; https://doi.org/10.3390/coatings13111894 - 04 Nov 2023

Viewed by 813

Abstract

Titanium coating on a steel substrate by surface technology can improve the corrosion resistance of steel. In this paper, the titanium TA2 coating was deposited on X80 steel by cold spraying equipment with a low-cost irregular powder. The effects of the carrier gas [...] Read more.

Titanium coating on a steel substrate by surface technology can improve the corrosion resistance of steel. In this paper, the titanium TA2 coating was deposited on X80 steel by cold spraying equipment with a low-cost irregular powder. The effects of the carrier gas temperature on the microstructure, microhardness, wear resistance, adhesion and corrosion resistance of titanium coatings, especially in a deep sea environment, were studied by methods of porosity analysis, thermal field emission scanning analysis, energy spectrum analysis, Vickers hardness tests, bonding strength tests, friction and wear tests and electrochemical tests. The results showed that as the carrier gas temperature increased from 300 °C to 900 °C, the porosity of the coating decreased to 0.93%, and the hardness and bonding strength of the coating increased to 247 HV_0.5 and 46.7 MPa, respectively. With the increase in hydrostatic pressure from 0.1 MPa to 40 MPa, the dimensional blunt current density of the titanium coating with 0.93% porosity was still in the order of 10⁻⁷ A·cm⁻² with the cast titanium TA2. Full article

(This article belongs to the Special Issue Advances in Deposition and Characterization of Hard Coatings)

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11 pages, 3026 KiB

Open AccessArticle

First Approach to Doping Silver into CrB₂ Thin Films Deposited by DC/HiPIMS Technology in Terms of Mechanical and Tribological Properties

by Martin Truchlý, Marián Haršáni, Adam Frkáň, Tomáš Fiantok, Martin Sahul, Tomáš Roch, Peter Kúš and Marián Mikula

Coatings 2023, 13(5), 824; https://doi.org/10.3390/coatings13050824 - 24 Apr 2023

Cited by 1 | Viewed by 1166

Abstract

Doping of transition metal diborides (TMB₂) films with soft metals (Ag, Au, Pt) can extend their application potential to tribological and biomedical fields. Here, a combination of direct current unbalanced magnetron sputtering (DC-UBMS) with high-power pulsed magnetron sputtering (HiPIMS) was used [...] Read more.

Doping of transition metal diborides (TMB₂) films with soft metals (Ag, Au, Pt) can extend their application potential to tribological and biomedical fields. Here, a combination of direct current unbalanced magnetron sputtering (DC-UBMS) with high-power pulsed magnetron sputtering (HiPIMS) was used to synthesize silver-doped CrB_2+x thin films on unheated substrates. All Ag–CrB_2+x thin films were over-stoichiometric with a B/Cr ratio ranging from 2.05 to 2.30 and silver content varying from 3 at.% to 29 at.%. X-ray diffraction demonstrates the amorphous character of the structure in the case of films with silver content ranging from 0 at.% to 8 at.%. A nanocrystalline structure containing a cubic Ag phase is formed in the films with higher silver content. The highest hardness of 26.6 GPa accompanied by the highest value of elastic modulus of 362 GPa was measured in undoped CrB_2.3 films. As the silver content in the Ag–CrB_2+x thin films increases, the hardness and elastic modulus values gradually decrease to 7.8 GPa and 187 GPa, respectively. The friction properties of CrB_2.3 films, expressed by the coefficient of friction against a steel ball of 0.72, are insufficient and limit their use in demanding industrial applications. However, silver doping significantly reduces the friction coefficient when the lowest value of 0.39 is measured in moderately hard Ag–CrB_2+x films with an Ag content of 17 at.%. The scratch test shows satisfactory adhesion of films to substrates even without additional heating during deposition. Full article

(This article belongs to the Special Issue Advances in Deposition and Characterization of Hard Coatings)

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10 pages, 2205 KiB

Open AccessArticle

Additive Manufacturing of Tungsten Carbide Surfaces with Extreme Wear Resistivity

by Florian Köhn, Michael Sedlmajer, Joachim Albrecht and Markus Merkel

Coatings 2021, 11(10), 1240; https://doi.org/10.3390/coatings11101240 - 13 Oct 2021

Cited by 5 | Viewed by 2925

Abstract

Steel surfaces have been coated with Co-based tungsten carbide (WC) in an additive printing process. This process leads to compact and extremely mechanically stable surfaces. We performed tribological measurements using WC counter bodies under dry conditions and severe mechanical load. Low coefficients of [...] Read more.

Steel surfaces have been coated with Co-based tungsten carbide (WC) in an additive printing process. This process leads to compact and extremely mechanically stable surfaces. We performed tribological measurements using WC counter bodies under dry conditions and severe mechanical load. Low coefficients of friction, even for rough surfaces, were found and the resulting wear rates were extraordinarily small, even when compared to high-quality PVD film with a similar composition. These findings suggest a wide field of application for this novel preparation process for wear-resistive surfaces. Full article

(This article belongs to the Special Issue Advances in Deposition and Characterization of Hard Coatings)

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