Coatings

12 pages, 9238 KiB

Open AccessArticle

Robust Superhydrophobic Coating with Mullite Fiber Framework

by Wensheng Zhong, Shilin Hu, Manyuan Wu, Bichen Xiong, Qiaowen Liu, Qingqing Jia, Yaming Liu and Hongwei Liao

Coatings 2022, 12(7), 1037; https://doi.org/10.3390/coatings12071037 - 21 Jul 2022

Cited by 1 | Viewed by 1829

Abstract

Superhydrophobic surfaces have received increasing attention due to their excellent water repellency, but the fragile stability of superhydrophobic coatings has been a huge hindrance to their applications. In this work, we constructed a layer of mullite fibers on the surface of a ceramic [...] Read more.

Superhydrophobic surfaces have received increasing attention due to their excellent water repellency, but the fragile stability of superhydrophobic coatings has been a huge hindrance to their applications. In this work, we constructed a layer of mullite fibers on the surface of a ceramic substrate using high-temperature molten salt. Then, we obtained a superhydrophobic surface with a contact angle greater than 150° via soaking the sample with an alcoholic sol containing modified particles. On the one hand, this interlaced three-dimensional fiber structure increases the surface area and roughness, providing more locations for attaching superhydrophobic particles, as well as improving the water repellency. On the other hand, this fiber layer has a height difference, which protects the superhydrophobic particles attached at lower positions, and when an external object contacts the surface, it gives priority to the stable mullite fibers, reducing the direct contact between superhydrophobic particles and external objects and improving the stability of the superhydrophobic coating. After abrasion with sandpaper, the sample with the mullite fiber layer showed excellent stability compared to the samples without the fiber layer, indicating the significant protective effect of the fiber layer. This paper provides a potential method to enhance the stability of superhydrophobic ceramic surfaces. Full article

(This article belongs to the Special Issue Recent Advances in Hydrophobic Coatings)

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11 pages, 25327 KiB

Open AccessArticle

Synthesis of Trivinylisooctyl POSS and Its Application in UV-Curing of Polyurethane Acrylate Coatings

by Yufeng Wang, Zhenheng Cao, Ziheng Wang and Aijuan Ma

Coatings 2022, 12(7), 1036; https://doi.org/10.3390/coatings12071036 - 21 Jul 2022

Cited by 2 | Viewed by 2141

Abstract

To improve the overall performance of polyurethane acrylic (PUAs) coatings applied to an iron or wood substrate, a modifier, trivinylisooctyl polyhedral oligomeric silsesquioxane (TVi^7iso–POSS), was successfully synthesized by a polycondensation reaction in the presence of an organotin catalyst. TVi^7iso–POSS [...] Read more.

To improve the overall performance of polyurethane acrylic (PUAs) coatings applied to an iron or wood substrate, a modifier, trivinylisooctyl polyhedral oligomeric silsesquioxane (TVi^7iso–POSS), was successfully synthesized by a polycondensation reaction in the presence of an organotin catalyst. TVi^7iso–POSS is a POSS derivative possessing three olefin and seven isooctyl bonds; its molecular structure was confirmed by FT-IR, ¹H-NMR, and mass spectrometry. The synthesized TVi^7iso–POSS was then used as a modifier with butyl methacrylate (BMA), dodecafluoroheptyl methacrylate (DFMA), difunctional PUA (PUA–2), and photo-initiator 1173 to produce a novel polyurethane coating (PFMPUAs) via UV-curing. The performance of the obtained PFMPUAs coating was analyzed via X-ray photoelectron spectrometry, SEM, atomic force microscopy, TGA, and differential scanning calorimetry. The newly synthesized modifier, TVi^7iso–POSS, enhanced the thermal stability, hardness, flexibility, impact resistance, and adhesion of the PUAs coating and maintained its good light transmittance. Moreover, the PFMPUAs coating exhibited better overall performance compared to the previously studied PUAs coating when the addition of TVi^7iso–POSS and DFMA was 15 wt.% of PUA–2. Therefore, the PFMPUAs coating has potential applications in the field of environmentally friendly coatings. Full article

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9 pages, 11774 KiB

Open AccessArticle

Tribological Properties of Chromia and Chromia Composite Coatings Deposited by Plasma Spraying

by Lukas Bastakys, Liutauras Marcinauskas, Mindaugas Milieška, Matas Grigaliūnas, Sebastjan Matkovič and Mindaugas Aikas

Coatings 2022, 12(7), 1035; https://doi.org/10.3390/coatings12071035 - 21 Jul 2022

Cited by 2 | Viewed by 2045

Abstract

Cr₂O₃ and Cr₂O₃–SiO₂-TiO₂ coatings are deposited on P265GH steel using atmospheric plasma spraying. The influence of silicon oxide—titanium oxide addition on the surface morphology of the coatings, phase composition and tribological properties under [...] Read more.

Cr₂O₃ and Cr₂O₃–SiO₂-TiO₂ coatings are deposited on P265GH steel using atmospheric plasma spraying. The influence of silicon oxide—titanium oxide addition on the surface morphology of the coatings, phase composition and tribological properties under non-lubricated sliding conditions are investigated. The addition of SiO₂-TiO₂ led to the formation of a more uniform surface morphology and reduce the surface roughness of the Cr₂O₃ coatings. The X-ray diffraction (XRD) studies indicated that both coatings are composed of an eskoloite Cr₂O₃ phase. The friction coefficients of the Cr₂O₃ coating are 0.504 and 0.431 when 1 N and 3 N loads were used, respectively. Meanwhile, the Cr₂O₃–SiO₂-TiO₂ coating demonstrated slightly lower values of friction coefficients under similar loads. The specific wear rate of the as-sprayed coating is reduced with the addition of SiO₂-TiO₂. It was found that the wear rates of the Cr₂O₃ and Cr₂O₃–SiO₂-TiO₂ coatings are up to 20 times lower compared to the steel substrate. This article is an expanded version of the “19th international conference on plasma physics and applications” conference abstract. Full article

(This article belongs to the Section Ceramic Coatings and Engineering Technology)

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8 pages, 442 KiB

Open AccessFeature PaperArticle

Sustainability Evaluation of AquaSun Antifouling Coating Production

by Rosaria Ciriminna, Antonino Scurria and Mario Pagliaro

Coatings 2022, 12(7), 1034; https://doi.org/10.3390/coatings12071034 - 21 Jul 2022

Cited by 4 | Viewed by 2351

Abstract

Relying on a cost-effective and green process that is technically and economically feasible on large scale is not enough to call a technology “sustainable”. We thus evaluate the sustainability of the production of the new “AquaSun” antifouling sol–gel coating with reference to each [...] Read more.

Relying on a cost-effective and green process that is technically and economically feasible on large scale is not enough to call a technology “sustainable”. We thus evaluate the sustainability of the production of the new “AquaSun” antifouling sol–gel coating with reference to each of the three main dimensions (economic, social, and environmental) of sustainable development. This study will hopefully assist in overcoming the “not invented here” syndrome that still affects many sol–gel technologies, including antifouling coatings derived via the sol–gel process. Full article

(This article belongs to the Section Ceramic Coatings and Engineering Technology)

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13 pages, 3165 KiB

Open AccessFeature PaperArticle

Mid-Infrared HgTe Colloidal Quantum Dots In-Situ Passivated by Iodide

by Zekang Liu, Peng Wang, Ran Dong, Wei Gong, Jingjie Li, Dichao Dai, Hui Yan and Yongzhe Zhang

Coatings 2022, 12(7), 1033; https://doi.org/10.3390/coatings12071033 - 21 Jul 2022

Cited by 3 | Viewed by 2295

Abstract

Today, colloidal quantum dots (CQDs) have received wide attention due to their properties of tunable infrared absorption. For example, HgTe colloidal quantum dots have shown excellent optical absorption (absorption coefficient α > 10⁴ cm⁻¹), spectral absorption tunability covering the entire [...] Read more.

Today, colloidal quantum dots (CQDs) have received wide attention due to their properties of tunable infrared absorption. For example, HgTe colloidal quantum dots have shown excellent optical absorption (absorption coefficient α > 10⁴ cm⁻¹), spectral absorption tunability covering the entire infrared atmospheric window, and even the terahertz (THz). However, the efficient surface passivation of HgTe CQDs was limited by the highly sterically hindered long-chain organic ligands. Here, we demonstrate a new method to synthesize monodisperse mid-infrared HgTe CQDs, and the preparation process of the Hg precursor solution is optimized. With I⁻ in-situ passivated on the surfaces, the spherical HgTe quantum dots are successfully synthesized with the tunability size from 8 to 15 nm. The noise current density of the photoconductive device is as low as 10⁻¹¹ A·Hz^−1/2 at 130 K with a frequency of 1 Hz. Full article

(This article belongs to the Special Issue Advances in Nanostructured Thin Films and Coatings)

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15 pages, 11967 KiB

Open AccessFeature PaperArticle

Tailoring Mechanical and Electrochemical Properties of the Cr₁₅Fe₂₀Co₃₅Ni₂₀Mo₁₀ High-Entropy Alloy via the Competition between Recrystallization and Precipitation Processes

by Bo Li, Kaisheng Ming, Lichen Bai, Jing Wang and Shijian Zheng

Coatings 2022, 12(7), 1032; https://doi.org/10.3390/coatings12071032 - 21 Jul 2022

Cited by 2 | Viewed by 1773

Abstract

A strategy to improve the mechanical and electrochemical properties of Cr₁₅Fe₂₀Co₃₅Ni₂₀Mo₁₀ (Mo₁₀) high-entropy alloys (HEA) by regulating the thermal-mechanical process was investigated. Due to the mutual competition between recrystallization and μ-phase precipitation [...] Read more.

A strategy to improve the mechanical and electrochemical properties of Cr₁₅Fe₂₀Co₃₅Ni₂₀Mo₁₀ (Mo₁₀) high-entropy alloys (HEA) by regulating the thermal-mechanical process was investigated. Due to the mutual competition between recrystallization and μ-phase precipitation behavior, the microstructure after annealing consists of recrystallized fine face-centered cubic grains with numerous annealing twins, non-recrystallized deformed grains with high-density dislocations as well as high-density nanoscale μ-phase precipitates. The combination of grain boundary strengthening, precipitation strengthening, and hetero-deformation induced strengthening endowed an ultrahigh yield strength of 1189 MPa and a uniform elongation of 17.5%. The increased yield strength activated the formation of stacking faults and deformation twinning as the additional deformation modes, which enabled the Mo₁₀ HEA to exhibit a high strain-hardening rate and thus maintained superior ductility and enhanced tensile strength. Most importantly, when high-density dislocations accumulate at the phase boundaries, the nanoscale μ-phase can plastically deform by dislocation slips and the formation of stacking faults, which can relieve the high stress concentrations and thus prevent the cracking. The electrochemical properties of the annealed Mo₁₀ HEA are decreased (compared to the homogenized ones), but can be optimized by adjusting the content and size and fraction of the μ-phase. This work sheds light on developing high-performance HEAs. Full article

(This article belongs to the Collection Strong, Ductile and Corrosion-Resistant High-Entropy Alloys)

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11 pages, 3606 KiB

Open AccessArticle

Detection of Biofilm Formation on Material Surfaces by Ag⁺ Coating

by Takeshi Kogo, Kazufumi Sugi, Hideyuki Kanematsu, Hotaka Kai, Akiko Ogawa, Nobumitsu Hirai, Toshiyuki Takahashi and Takehito Kato

Coatings 2022, 12(7), 1031; https://doi.org/10.3390/coatings12071031 - 21 Jul 2022

Cited by 1 | Viewed by 4233

Abstract

The evaluation of biofilm formation is important, given the ubiquity and problematic nature of biofilms in industrial and medical settings, as well as in everyday life. Basically, biofilms are formed on substrates. Therefore, it is essential to consider the properties of the substrates [...] Read more.

The evaluation of biofilm formation is important, given the ubiquity and problematic nature of biofilms in industrial and medical settings, as well as in everyday life. Basically, biofilms are formed on substrates. Therefore, it is essential to consider the properties of the substrates during biofilm evaluation. The common dye staining method to evaluate biofilm formation requires a short evaluation time and enables the evaluation of a large area of the sample. Furthermore, it can be easily determined visually, and quantitative evaluation is possible by quantifying color adsorption. Meanwhile, the dye staining method has the problem of adsorption even on substrate surfaces where no biofilm has formed. Therefore, in this study, we focused on Ag⁺ reduction reaction to devise a novel biofilm evaluation method. Ag⁺ is highly reductive and selectively reacts with organic substances, such as saccharides, aldehydes, and proteins contained in biofilms, depositing as metallic Ag. First, to simply evaluate biofilm formation, we used a glass substrate as a smooth, transparent, and versatile oxide material. We observed that the amount of Ag deposited on the substrate was increased proportionally to the amount of biofilm formed under light irradiation. Upon comparing the Ag deposition behavior and adsorption behavior of crystal violet, we discovered that for short immersion times in AgNO₃ solution, Ag deposition was insufficient to evaluate the amount of biofilm formation. This result suggests that the Ag reduction reaction is more insensitive than the crystal violet adsorption behavior. The results of the Ag deposition reaction for 24 h showed a similar trend to the crystal violet dye adsorption behavior. However, quantitative biofilm evaluation using the proposed method was difficult because of the Ag⁺ exchange with the alkali metal ions contained in the glass substrate. We addressed this issue by using the basic solution obtained by adding an ammonia solution to aqueous AgNO₃. This can cause Ag⁺ to selectively react with the biofilm, thus enabling a more accurate quantitative evaluation. The optimum was determined at a ratio of distilled water to aqueous ammonia solution of 97:3 by weight. This biofilm was also evaluated for materials other than ceramics (glass substrate): organic material (polyethylene) and metal material (pure iron). In the case of polyethylene, a suitable response and evaluation of biofilm formation was successfully achieved using this method. Meanwhile, in the case of pure iron, a significantly large lumpy deposit of Ag was observed. The likely reason is that Ag precipitation occurred along with the elution of iron ions because of the difference in ionization tendency. It could be concluded that the detection of biofilm formation using this method was effective to evaluate biofilm formation on materials, in which the reduction reaction of [Ag(NH₃)₂]⁺ does not occur. Thus, a simple and relatively quantitative evaluation of biofilms formed on substrates is possible using this method. Full article

(This article belongs to the Special Issue Formation of Biofilms and Its Applications)

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18 pages, 8548 KiB

Open AccessArticle

Experimental Research on Magnesium Phosphate Cements Modified by Fly Ash and Metakaolin

by He Liu, Qidong Feng, Yanhai Yang, Jingyi Zhang, Jian Zhang and Guangchao Duan

Coatings 2022, 12(7), 1030; https://doi.org/10.3390/coatings12071030 - 21 Jul 2022

Cited by 9 | Viewed by 2384

Abstract

To increase performance and save costs when utilizing magnesium phosphate cements (MPC) to repair a damaged building structure or a cement pavement, MPC is typically combined with fly ash (FA) and metakaolin (MK). The influence of FA and MK on the workability, rheological [...] Read more.

To increase performance and save costs when utilizing magnesium phosphate cements (MPC) to repair a damaged building structure or a cement pavement, MPC is typically combined with fly ash (FA) and metakaolin (MK). The influence of FA and MK on the workability, rheological characteristics, flexural strength, compressive strength, and drying shrinkage of MPC was investigated in this research. MPC samples with different percentages of FA and MK by weight replacement were prepared. The results indicate that an appropriate dosage of MK and FA could decrease MPC fluidity and delay the setting time. MPC’s yield stress and plastic viscosity were increased when MK was added. FA has a negative influence on flexural and compressive strength as compared to control MPC and the compressive strength of MPC with MK increases and then decreases. The drying shrinkage of MPC containing MK and FA is superior to control mixture. MPC with 10% FA and 10% MK has the best-modified performance in terms of the comprehensive performance of MPC at all test ages. Full article

(This article belongs to the Special Issue Novel Green Pavement Materials and Coatings)

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40 pages, 20619 KiB

Open AccessArticle

Research on Micro-Mechanics Modelling of TPU-Modified Asphalt Mastic

by Xin Jin, Fengchi Wang, Zhichen Wang, Ye Yang, Zhaoyang Chu, Naisheng Guo and Xin Lv

Coatings 2022, 12(7), 1029; https://doi.org/10.3390/coatings12071029 - 20 Jul 2022

Cited by 2 | Viewed by 1904

Abstract

To explore the interactions and mechanisms of Thermoplastic polyurethane (TPU)-modified asphalt with different kinds of mineral fillers, a micro-mechanical model for TPU-modified asphalt mastic was established, which considered the interaction between asphalt and mineral powder to effectively analyze the internal mechanisms affecting the [...] Read more.

To explore the interactions and mechanisms of Thermoplastic polyurethane (TPU)-modified asphalt with different kinds of mineral fillers, a micro-mechanical model for TPU-modified asphalt mastic was established, which considered the interaction between asphalt and mineral powder to effectively analyze the internal mechanisms affecting the rheological properties of TPU-modified asphalt mastic. In this study, according to the micro-mechanics of composites’ principles, the dynamic shear modulus (|G^*|) of asphalt mastic with different mass ratios of filler/asphalt (F/A) was calculated by the homogenize morphologically representative pattern (H-MRP) model. The key ratio of F/A, which is close to the test result, can be determined, and a four-phase H-MRP model of the TPU modified asphalt mastic was established after considering the structure of asphalt layer thickness. The results were interpreted based on the known reactions of TPU with asphalt model compounds. The |G^*| of TPU-modified asphalt mastic was predicted by using this model. Furthermore, the effects of the complex shear modulus, Poisson’s ratio of TPU-modified asphalt, Poisson’s ratio, particle size of mineral powder, and thickness of the structural asphalt layer in the |G^*| of TPU-modified asphalt mastic were analyzed in the whole-model construction, as well as the internal mechanism of the |G^*| of TPU modified asphalt mastic. In addition, can also be found the predicted value of |G^*| calculated by the four-phase H-MRP model is close to the experimental value after choosing a structural asphalt layer of appropriate thickness. Full article

(This article belongs to the Special Issue Science and Technology of Pavement Coatings Materials)

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12 pages, 3759 KiB

Open AccessArticle

Corrosion Degradation Behaviors of Ti6Al4V Alloys in Simulated Marine Environments

by Wei Chen, Dalu Zhang, Enlei Wang, Feng Yan, Lin Xiang and Zhiwen Xie

Coatings 2022, 12(7), 1028; https://doi.org/10.3390/coatings12071028 - 20 Jul 2022

Cited by 4 | Viewed by 2259

Abstract

Detailed tests and characterizations were used to investigate the corrosion degradation behaviors of Ti6Al4V alloys in simulated marine environments. These alloys suffered from very slight pitting and a miniscule weight loss of 0.018 mg/cm² during the 50 cycle salt spray exposure but [...] Read more.

Detailed tests and characterizations were used to investigate the corrosion degradation behaviors of Ti6Al4V alloys in simulated marine environments. These alloys suffered from very slight pitting and a miniscule weight loss of 0.018 mg/cm² during the 50 cycle salt spray exposure but experienced significant oxygen erosion in the high-temperature oxidation test, resulting in a high weight gain of 2.657 mg/cm² at 400 h. The oxidation and degradation reactions simultaneously occurred during the high-temperature hot salt test. The chlorine (Cl₂) induced by the eutectic reaction of the mixed salts accelerated the degradation of the substrate and led to a higher weight gain of 4.265 mg/cm² at 400 h. In contrast, this alloy suffered from severe corrosion damage during the high-temperature hot salt–water vapor synergy test. The degradation of TiO₂, Al₂O₃, and V₂O₅ was aggravated by the synergistic action of chlorine salt and water. The reaction forming hydrochloric acid (HCl) further degraded the matrix metal and consequently led to a high weight loss of 16.358 mg/cm² at 400 h. These current findings provide a comprehensive understanding for the degradation mechanisms of Ti alloys in these specific marine environments. Full article

(This article belongs to the Special Issue Recent Advancement in Thin Film Deposition, Characterization, and Surface Engineering)

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18 pages, 4247 KiB

Open AccessArticle

Effect of Modified Tetraethyl Orthosilicate Surface Treatment Agents on the Permeability of Airport Pavement Concrete

by Tianlun Li and Yonggen Wu

Coatings 2022, 12(7), 1027; https://doi.org/10.3390/coatings12071027 - 20 Jul 2022

Cited by 4 | Viewed by 1993

Abstract

In this paper, three modified tetraethyl orthosilicate surface treatment agents were prepared by using tetraethyl orthosilicate (TEOS) as the preparation monomer, isobutyltriethoxysilane (IBTS) as the hybridizer, and acrylic acid, phosphoric acid, and hydrochloric acid as the catalysts. The effects of the three modified [...] Read more.

In this paper, three modified tetraethyl orthosilicate surface treatment agents were prepared by using tetraethyl orthosilicate (TEOS) as the preparation monomer, isobutyltriethoxysilane (IBTS) as the hybridizer, and acrylic acid, phosphoric acid, and hydrochloric acid as the catalysts. The effects of the three modified tetraethyl orthosilicate surface treatment agents on the permeability of airport pavement surface concrete were investigated by water absorption tests, water contact angle tests, water penetration resistance tests, chloride ion penetration resistance tests, and carbonation tests, and the mechanisms of action of the modified tetraethyl orthosilicate surface treatment agents were analyzed by microscopic tests. The results showed that all three tetraethyl orthosilicate surface treatment agents could significantly improve the impermeability of concrete, among which the modified tetraethyl orthosilicate surface treatment agent with hydrochloric acid as the catalyst had the most obvious effect on the improvement of the impermeability of concrete. Acrylic acid was weaker than hydrochloric acid as the catalyst of a modified tetraethyl orthosilicate surface treatment agent for the improvement of concrete impermeability; it was only slightly stronger than hydrochloric acid as the catalyst of modified tetraethyl orthosilicate surface treatment agent in terms of the improvement of concrete’s resistance to water penetration, and the difference between the two was not significant. Phosphoric acid as a catalyst of the modified tetraethyl orthosilicate surface treatment agent was the least effective for concrete impermeability; it was only stronger than the other two modified tetraethyl orthosilicate surface treatment agents in the improvement of concrete resistance to carbonation, and the carbonation depth of the concrete was only 1 mm in 28 days. SEM and MIP tests showed that the modified tetraethyl orthosilicate surface treatment agents improved the impermeability of concrete mainly by producing additional hydrated calcium silicate gel to plug microcracks and pores, reduce the total porosity of the concrete and the number of multi-harmful and harmful pores, and improve the compactness of the concrete. The test results can provide a reference for the development of modified tetraethyl orthosilicate surface treatment agents and their application in airport pavement surface engineering. Full article

(This article belongs to the Special Issue Thin-Film Synthesis, Characterization and Properties)

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4 pages, 196 KiB

Open AccessEditorial

Special Issue: Biofilm Composition and Applications

by Bindu Subhadra

Coatings 2022, 12(7), 1026; https://doi.org/10.3390/coatings12071026 - 20 Jul 2022

Cited by 2 | Viewed by 1801

Abstract

Biofilms can be formed on both biotic and abiotic surfaces, including on living tissues, indwelling medical devices, industrial or portable water system piping, and natural aquatic systems [...] Full article

(This article belongs to the Special Issue Biofilms: Composition and Applications)

9 pages, 15217 KiB

Open AccessEditor’s ChoiceArticle

Mechanical Properties and Thermal Stability of CrZrN/CrZrSiN Multilayer Coatings with Different Bilayer Periods

by Hoe-Kun Kim, Sung-Min Kim and Sang-Yul Lee

Coatings 2022, 12(7), 1025; https://doi.org/10.3390/coatings12071025 - 19 Jul 2022

Cited by 7 | Viewed by 2270

Abstract

The CrZrN/CrZrSiN multilayer coatings at a bilayer period range decreasing from 1.35 μm to 0.45 μm were synthesized on a Si (100) wafer and WC-6 wt.% Co substrate using a closed-field unbalanced magnetron sputter, and the thickness effects on the mechanical properties and [...] Read more.

The CrZrN/CrZrSiN multilayer coatings at a bilayer period range decreasing from 1.35 μm to 0.45 μm were synthesized on a Si (100) wafer and WC-6 wt.% Co substrate using a closed-field unbalanced magnetron sputter, and the thickness effects on the mechanical properties and thermal stability were investigated. The CrZrN/CrZrSiN multilayer coatings showed high hardness and elastic modulus in the ranges of 28 to 33 GPa and 255 to 265 GPa, respectively, and the friction coefficient showed the lowest value of 0.24 on the multilayer coating with a bilayer period of 0.54 μm. The bilayer periods affected the adhesion strength of the multilayer coatings. From the scratch test, the critical load (Lc2) steadily increased with the decreasing of the bilayer period, and the CrZrN/CrZrSiN multilayer coating with a bilayer period of 0.45 μm showed the highest critical load (Lc2) of 79 N. In the case of the annealing test, the bilayer periods affected the thermal stability of the multilayer coatings, and the CrZrN/CrZrSiN multilayer coatings with 0.54 μm showed a maximum hardness value of approximately 30 GPa up to 800 °C. Full article

(This article belongs to the Special Issue Technologies of Coatings and Surface Hardening for Tool Industry II)

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4 pages, 205 KiB

Open AccessEditorial

Progress in Sustainability and Durability of Concrete and Mortar Composites

by Ofelia Corbu and Ionut-Ovidiu Toma

Coatings 2022, 12(7), 1024; https://doi.org/10.3390/coatings12071024 - 19 Jul 2022

Cited by 8 | Viewed by 1610

Abstract

The origins of concrete as a construction material date back more than 2000 years ago, but the origins of the term itself are still under debate due to its many different interpretations throughout history [...] Full article

(This article belongs to the Special Issue Recent Progress in Sustainability and Durability of Concrete and Mortar Composites)

17 pages, 3752 KiB

Open AccessReview

Microstructures, Corrosion Resistance and Wear Resistance of High-Entropy Alloys Coatings with Various Compositions Prepared by Laser Cladding: A Review

by Kefeng Lu, Jian Zhu, Delin Guo, Minghui Yang, Huajian Sun, Zekun Wang, Xidong Hui and Yongling Wu

Coatings 2022, 12(7), 1023; https://doi.org/10.3390/coatings12071023 - 19 Jul 2022

Cited by 27 | Viewed by 3915

Abstract

Nowadays, high-entropy alloys (HEAs) have become a hot research topic in the field of coating materials. However, HEAs have a large wide range of compositional systems, and the differences in their composition inevitably lead to the significant variations in the matching process parameters [...] Read more.

Nowadays, high-entropy alloys (HEAs) have become a hot research topic in the field of coating materials. However, HEAs have a large wide range of compositional systems, and the differences in their composition inevitably lead to the significant variations in the matching process parameters of laser cladding and post-treatment methods, which in turn give the coatings a broad range of microstructures and protective properties. Therefore, it is crucial to review and summarize the research progresses on laser cladding HEA coatings to provide a reference for obtaining high-performance HEA coatings and further expand the application of HEA coatings. This work describes the working mechanism of laser cladding and illustrates the advantages and drawbacks of laser cladding in detail. The effects of the addition of alloying elements, process parameters and post-treatment techniques on the microstructures and properties of the coatings are thoroughly reviewed and analyzed. In addition, the correlations between the chemical compositions of HEAs, process parameters of laser cladding, post-treatment techniques and the microstructure and protective properties of the coatings are investigated and summarized. On this basis, the future development direction of HEA coatings is outlined. Full article

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14 pages, 3269 KiB

Open AccessFeature PaperArticle

On the Control of Hot Nickel Target Magnetron Sputtering by Distribution of Power Pulses

by Rafal Chodun, Bartosz Wicher, Katarzyna Nowakowska-Langier, Roman Minikayev, Marlena Dypa-Uminska and Krzysztof Zdunek

Coatings 2022, 12(7), 1022; https://doi.org/10.3390/coatings12071022 - 19 Jul 2022

Cited by 5 | Viewed by 2211

Abstract

This paper presents the experimental results of high-temperature sputtering of nickel targets by the Gas Injection Magnetron Sputtering (GIMS) technique. The GIMS technique is a pulsed magnetron sputtering technique that involves the generation of plasma pulses by injecting small doses of gas into [...] Read more.

This paper presents the experimental results of high-temperature sputtering of nickel targets by the Gas Injection Magnetron Sputtering (GIMS) technique. The GIMS technique is a pulsed magnetron sputtering technique that involves the generation of plasma pulses by injecting small doses of gas into the zone of the magnetron target surface. Using a target with a dedicated construction to limit heat dissipation and the proper use of injection parameters and electrical power density, the temperature of the target during sputtering can be precisely controlled. This feature of the GIMS technique was used in an experiment with sputtering nickel targets of varying thicknesses and temperatures. Plasma emission spectra and current-voltage waveforms were studied to characterize the plasma process. The thickness, structure, phase composition, and crystallite size of the nickel layers produced on silicon substrates were investigated. Our experiment showed that although the most significant increase in growth kinetics was observed for high temperatures, the low sputtering temperature range may be the most interesting from a practical perspective. The excited plasma has the highest energy in the sputtering temperature range, just above the Curie temperature. Full article

(This article belongs to the Special Issue Advances in Thin Film Fabrication by Magnetron Sputtering)

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29 pages, 19088 KiB

Open AccessArticle

Contribution to the Research and Development of Innovative Building Components with Embedded Energy-Active Elements

by Daniel Kalús, Daniela Koudelková, Veronika Mučková, Martin Sokol and Mária Kurčová

Coatings 2022, 12(7), 1021; https://doi.org/10.3390/coatings12071021 - 19 Jul 2022

Cited by 5 | Viewed by 1977

Abstract

The research described in this study focuses on the innovation and optimization of building envelope panels with integrated energy-active elements in the thermal barrier function. It is closely related to developing and implementing the prototype prefabricated house IDA I with combined building-energy systems [...] Read more.

The research described in this study focuses on the innovation and optimization of building envelope panels with integrated energy-active elements in the thermal barrier function. It is closely related to developing and implementing the prototype prefabricated house IDA I with combined building-energy systems using renewable energy sources. We were inspired by the patented ^®ISOMAX panel and system, which we have been researching and innovating for a long time. The thermal barrier has the function of eliminating heat loss/gain through the building envelope. By controlling the heat/cold transfer in the thermal barrier, it is possible to eliminate the thickness of the thermal insulation of the building envelope and thus achieve an equivalent thermal resistance of the building structure that is equal to the standard required value. The technical solution of the ISOMAX panel also brings, besides the use of the thermal barrier function, the function of heat/cold accumulation in the load-bearing part of the building envelope. Our research aimed to design and develop a panel for which the construction would be optimal in terms of thermal barrier operation and heat/cold accumulation. As the production panels in the lost formwork of expanded polystyrene (according to the patented system) proved to be too complicated and time consuming, and often showed shortcomings from a structural point of view, the next goal was to design a new, statically reliable panel construction with integrated energy-active elements and a time-saving, cost-effective, unified production directly in the panel factory. In order to develop and design an innovative panel with integrated energy-active elements, we analyzed the composition of the original panel and designed the composition of the innovative panel. We created mathematical–physical models of both panels and analyzed their energy potential. By induction and an analog form of formation, we designed the innovative panel. Based on the synthesis of the knowledge obtained from the scientific analysis and the transformation of this data, most of the building components and all the panels with integrated energy-active elements were manufactured directly in the prefabrication plant. Subsequently, the prototype of the prefabricated house IDA I was realized. The novelty of our innovative building envelope panel solution lies in the panel’s design, which has a heat loss/gain that is 2.6 times lower compared to the ISOMAX panel. Full article

(This article belongs to the Special Issue 10th Anniversary of Coatings: Invited Papers in "Surface Characterization, Deposition and Modification" Section)

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17 pages, 2026 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Gravure Printing for PVDF Thin-Film Pyroelectric Device Manufacture

by Giuliano Sico, Maria Montanino, Fausta Loffredo, Carmela Borriello and Riccardo Miscioscia

Coatings 2022, 12(7), 1020; https://doi.org/10.3390/coatings12071020 - 19 Jul 2022

Cited by 9 | Viewed by 3629

Abstract

Pyroelectric energy harvesting is one of the more recent and promising solid-state approaches for directly converting time-dependent temperature fluctuations into electric energy. Conventional printing technologies can offer many advantages for the production of pyroelectric thin-film-based devices, such as low cost, low temperature, the [...] Read more.

Pyroelectric energy harvesting is one of the more recent and promising solid-state approaches for directly converting time-dependent temperature fluctuations into electric energy. Conventional printing technologies can offer many advantages for the production of pyroelectric thin-film-based devices, such as low cost, low temperature, the use of flexible substrates and shaping at the same time as deposition. Nevertheless, some issues related to low printed thickness and film-forming microstructure control need to be addressed. In this exploratory study, the possibility of exploiting the highly attractive gravure printing process for the potential industrial manufacture of flexible polyvinylidene fluoride (PVDF) thin-film pyroelectric devices was investigated. By the use of corona pre-treatment of the printing substrate and low-temperature polar solvent evaporation, multilayer gravure-printed PVDF pyroelectric devices were successfully manufactured for the first time, achieving a maximum generated current of 0.1 nA at 2.5 K/s from a device with an active area of 1 cm². Considering the very low thermal inertia and performance scaling by the area expected for pyroelectric thin-film-based devices, combined with the upscaling potential of roll-to-roll gravure printing, our results provide new opportunities for on-demand, low-cost pyroelectric device manufacture and their integration in hybrid harvesters. Full article

(This article belongs to the Special Issue Printed Functional Thin Films for Electronic, Optoelectronic and Sensing Applications)

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Graphical abstract

15 pages, 3648 KiB

Open AccessArticle

First-Principles Study on the Adsorption and Dissociation Behavior of H₂ on the Surface of a Plutonium–Gallium System

by Longxian Li, Min Zhu, Huang Huang, Tianxi Liang, Huan Su and Baiyu Xue

Coatings 2022, 12(7), 1019; https://doi.org/10.3390/coatings12071019 - 19 Jul 2022

Cited by 1 | Viewed by 1839

Abstract

In order to understand the mechanism of hydrogen interaction on the surface of a plutonium–gallium system, the adsorption and dissociation behaviors of hydrogen molecules on the surface of a plutonium–gallium system were studied using the first-principles approach. The results show that the physical [...] Read more.

In order to understand the mechanism of hydrogen interaction on the surface of a plutonium–gallium system, the adsorption and dissociation behaviors of hydrogen molecules on the surface of a plutonium–gallium system were studied using the first-principles approach. The results show that the physical adsorption of hydrogen molecules occurs on the surface with a small degree of interaction; the most stable adsorption configuration is hollow-site parallel adsorption (H-b-hor1). During adsorption, charge transfer occurs mainly in the first atomic layer, and the density of states and surface function does not change significantly before and after adsorption. When the hydrogen molecule overcomes the energy barrier of 4.96 eV, it dissociates into two hydrogen atoms chemisorbed on the surface, which reduces the energy of the whole system by 1.95 eV. The essence of the hydrogen atom–surface interaction is that the 1s orbital of the hydrogen atom hybridizes with the 4s and 4p orbitals of the gallium atom and the 6s, 7s, and 6d orbitals of the plutonium atom to form a chemical bond. Full article

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11 pages, 5641 KiB

Open AccessArticle

Growth Kinetics and Mechanical Properties of Rare-Earth Vanadiumizing Layer on GCr15 Steel Surface

by Lingyao Meng, Jian Shang, Mengjiu Zhang, Aijun Xie and Yue Zhang

Coatings 2022, 12(7), 1018; https://doi.org/10.3390/coatings12071018 - 19 Jul 2022

Cited by 3 | Viewed by 1519

Abstract

In this paper, rare-earth vanadiumizing layers were prepared on the surface of GCr15 steel by powder pack cementation. The tissue thicknesses of the vanadiumizing layers were characterized by metallographic microscopy, scanning electron microscopy, X-ray diffraction, electron microprobe analysis and microhardness testing at 1173, [...] Read more.

In this paper, rare-earth vanadiumizing layers were prepared on the surface of GCr15 steel by powder pack cementation. The tissue thicknesses of the vanadiumizing layers were characterized by metallographic microscopy, scanning electron microscopy, X-ray diffraction, electron microprobe analysis and microhardness testing at 1173, 1193, 1213 and 1223 K for 1, 3, 5 and 7 h, respectively, and the growth kinetics of the rare-earth vanadiumizing layers were investigated first. The experimental results showed that: a dense and uniform vanadiumizing layer was obtained on the surface of the substrate, and the layer mainly consisted of VC_x and α-Fe; the thickness of the vanadiumizing layer increased with the increase in heating temperature and holding time, and the variation range was 4.65–12.65 µm; the microhardness of the vanadiumizing layer increased with the increase in heating temperature and holding time, and the variation range was 1892.3–2698.6 HV, compared with the substrate. The electron probe microanalysis showed that the rare earth entered the diffusion layer and affected its tissue hardness. The experimental diffusion activation energy of the GCr15 steel powder-embedded rare-earth vanadiumizing layer was 164.85 KJ/mol. Full article

(This article belongs to the Section Surface Characterization, Deposition and Modification)

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17 pages, 5525 KiB

Open AccessArticle

Dielectric Properties of Plasma-Sprayed Fully Natural Garnets

by Pavel Ctibor, Josef Sedláček and Libor Straka

Coatings 2022, 12(7), 1017; https://doi.org/10.3390/coatings12071017 - 18 Jul 2022

Cited by 1 | Viewed by 1569

Abstract

Various kinds of natural garnets belonging to the almandine type (3FeO·Al₂O₃·3SiO₂) were sprayed by plasma spray technique to build coatings on metallic substrates. The experimental garnet powders came from different mines in the Czech Republic and Mongolia. [...] Read more.

Various kinds of natural garnets belonging to the almandine type (3FeO·Al₂O₃·3SiO₂) were sprayed by plasma spray technique to build coatings on metallic substrates. The experimental garnet powders came from different mines in the Czech Republic and Mongolia. After coating and cooling the substrates were removed. In this way, self-supporting plates were obtained and further studied with microscopy, X-ray diffraction, and dielectric spectroscopy. Mechanical properties were in our focus as well. Microhardness was measured on cross sections dedicated to microstructure observation. Wear resistance in wet conditions was tested in a slurry. Reflectance was measured applying visible and infrared (VIS-NIR) radiation. Dielectric properties of coatings were studied at low voltage capacitance, loss tangent and also under direct current (DC) resistance. The results show that garnet minerals are interesting candidates for various optical and electronic applications; they have similar dielectric behavior as, for example, aluminum oxide or similar high-purity synthetic oxides, and, simultaneously, they have extraordinarily low reflectance in VIS-NIR radiation. The differences between natural powders and resulting coatings are discussed in connection with their chemical and phase compositions. Full article

(This article belongs to the Special Issue High-Performance Dielectric Ceramic for Energy Storage Capacitors)

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2 pages, 163 KiB

Open AccessEditorial

Special Issue: Surface Modification of Engineering and Functional Materials

by Ivan A. Pelevin and Dmitriy Yu. Ozherelkov

Coatings 2022, 12(7), 1016; https://doi.org/10.3390/coatings12071016 - 18 Jul 2022

Cited by 1 | Viewed by 1356

Abstract

The ongoing development of both engineering and functional materials is leading to new requirements in terms of their surface properties [...] Full article

(This article belongs to the Special Issue Surface Modification of Engineering and Functional Materials)

32 pages, 11312 KiB

Open AccessReview

Design Methodology and Application of Surface Texture: A Review

by Ange Nsilani Kouediatouka, Qiang Ma, Qi Liu, Fagla Jules Mawignon, Faisal Rafique and Guangneng Dong

Coatings 2022, 12(7), 1015; https://doi.org/10.3390/coatings12071015 - 18 Jul 2022

Cited by 38 | Viewed by 5712

Abstract

Surface texture is regarded as a promising solution for enhancing the tribological features of industrial materials due to its outstanding benefits, such as minimization of the contact area, enhancement of the load bearing capacity, storage of the lubricant, and management of the transition [...] Read more.

Surface texture is regarded as a promising solution for enhancing the tribological features of industrial materials due to its outstanding benefits, such as minimization of the contact area, enhancement of the load bearing capacity, storage of the lubricant, and management of the transition between lubrication regimes. Surface texture can be processed under either liquid or gas conditions. As compared to laser ablation in air, employing liquids or other gases as ablation media provides high accuracy and uniformity by limiting the heat-affected zone (HAZ) and other undesired defects to a large extent, as well as high crater structural features. In addition, the synergistic use of different liquid, solid, and additive lubricants with surface roughness recently demonstrated excellent performance. Therefore, surface texture helps to improve the tribological characteristics of a material. This paper reviews the design methodologies and applications of surface texture, emphasizing the proper selection of the appropriate laser parameters and ambient conditions for the best texture quality and functionality. Recent texture geometric design features to improve the film thickness and the self-lubricating system are presented. The ablation environment is explored using various media. The interaction between the lubricants’ types and surface textures is explored based on the operating conditions. Furthermore, surface texture applications using superhydrophobic surfaces, anti-drag, and vibration and noise friction are discussed. We hope that this review plays an enlightening role in follow-up research on laser surface texture. Full article

(This article belongs to the Section Tribology)

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14 pages, 5111 KiB

Open AccessArticle

The Correlation of Plasma Characteristics to the Deposition Rate of Plasma Polymerized Methyl Methacrylate Thin Films in an Inductively Coupled Plasma System

by Stephen T. Hsieh, Himanshu Mishra, Nima Bolouki, Weite Wu, Chuan Li and Jang-Hsing Hsieh

Coatings 2022, 12(7), 1014; https://doi.org/10.3390/coatings12071014 - 18 Jul 2022

Cited by 3 | Viewed by 2060

Abstract

A plasma system attached with one internal coil (for generating inductively coupled plasma) and two sputtering carbon targets was set up to deposit PP-MMA (plasma polymerized methyl methacrylate) thin films. PP-MMA was used as a model material in the present study. In the [...] Read more.

A plasma system attached with one internal coil (for generating inductively coupled plasma) and two sputtering carbon targets was set up to deposit PP-MMA (plasma polymerized methyl methacrylate) thin films. PP-MMA was used as a model material in the present study. In the experiment, the working pressure and Ar/MMA flow ratio were varied, which resulted in the change in plasma conditions as well as the deposition rates. The optical emission spectroscopy (OES) method was applied to identify the presence of the excited species related to the fragmented monomer. In addition, the electron temperature and electron density were determined using the modified Boltzmann plot and line-ratio method, according to the measured OES spectra. The deposition rate of the PMMA film was then correlated with the determined plasma characteristics. To determine the vibrational modes of the deposited PP-MMA films, Fourier transformed infrared spectrometry (FTIR) was used. The highest deposition rate of PP-MMA could be obtained with the optimized working pressure and Ar/MMA volume ratio. This could be related to the plasma characteristics that contribute to the fragmentation of the monomer in the plasma. Full article

(This article belongs to the Section Plasma Coatings, Surfaces & Interfaces)

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3 pages, 180 KiB

Open AccessEditorial

Special Issue: Environmental Corrosion of Metals and Its Prevention: An Overview and Introduction to the Special Issue

by Boxin Wei and Jin Xu

Coatings 2022, 12(7), 1013; https://doi.org/10.3390/coatings12071013 - 18 Jul 2022

Cited by 3 | Viewed by 1723

Abstract

Corrosion is a natural process of deterioration and an extremely costly problem [...] Full article

(This article belongs to the Special Issue Environmental Corrosion of Metals and Its Prevention)

16 pages, 6465 KiB

Open AccessArticle

Preparation and Characterization of the Cr-Nanodiamonds/MoN Coatings with Performant Mechanical Properties

by Vadzim Chayeuski, Abdelhafed Taleb, Valery Zhylinski, Andrei Kuleshov and Roman Shtempliuk

Coatings 2022, 12(7), 1012; https://doi.org/10.3390/coatings12071012 - 18 Jul 2022

Cited by 4 | Viewed by 2087

Abstract

This paper presents the results of a study on the preparation and characterization of a Cr-DND/MoN detonation chromium-nanodiamond coating deposited on cemented tungsten carbide (WC–3 wt.% Co) mill blades using Arc-PVD and electrodeposition methods. The physical and mechanical characteristics of the coatings were [...] Read more.

This paper presents the results of a study on the preparation and characterization of a Cr-DND/MoN detonation chromium-nanodiamond coating deposited on cemented tungsten carbide (WC–3 wt.% Co) mill blades using Arc-PVD and electrodeposition methods. The physical and mechanical characteristics of the coatings were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), XRD analysis, Raman spectroscopy, micro-identification, and scratch test (evaluation of the coating adhesion). It was shown that the Cr-DND/MoN coating consists of successive layers of Cr-DND (top), Cu (middle) and MoN (bottom) with separate phases of γ-Mo₂N, α-Mo, α-Cu, Cr-DND and nanodiamonds. The Cr-DND composite electrochemical coating (CEC) was deposited from the conventional chromium plating electrolyte with the addition of nanodiamonds. The copper interlayer was deposited by the Arc-PVD method on the surface of the MoN coating to improve the adhesion strength of the Cr-DND CEC. The coating showed an optimum microhardness of about 14 ± 1 GPa and good adhesion with a critical load L_c of about 93 N. In addition to the expected experimental results, the coating has high wear resistance, confirmed by scratch tests. Full article

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18 pages, 6227 KiB

Open AccessArticle

Effect of hBN on Corrosion and Wear Performances of DC Electrodeposited NiW and NiW–SiC on Brass Substrates

by Mina Dadvand and Oumarou Savadogo

Coatings 2022, 12(7), 1011; https://doi.org/10.3390/coatings12071011 - 18 Jul 2022

Cited by 12 | Viewed by 3273

Abstract

Crack-free and uniform nickel–tungsten (NiW) coatings and their composite coatings filled with ceramic particles such as silicon carbide (SiC) and hexagonal-boron nitride (hBN) were deposited on brass substrates by applying direct current (DC) waveforms. Among all coatings, NiW–SiC–hBN coatings displayed the noblest corrosion [...] Read more.

Crack-free and uniform nickel–tungsten (NiW) coatings and their composite coatings filled with ceramic particles such as silicon carbide (SiC) and hexagonal-boron nitride (hBN) were deposited on brass substrates by applying direct current (DC) waveforms. Among all coatings, NiW–SiC–hBN coatings displayed the noblest corrosion potential (−0.49 V) and lowest current density (4.36 × 10⁻⁶ A·cm⁻²). It also seems that addition of hBN and SiC ceramic particles to NiW matrix remarkably improved the wear performance of the NiW coatings. However, NiW–hBN exhibited the lowest wear volume (48.84 × 10³ µm³) and the friction coefficient of 0.1 due to ultra–low friction coefficient of hBN particles. Full article

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10 pages, 5469 KiB

Open AccessArticle

Enhancing Corrosion Performance of Cold-Sprayed Titanium/Baghdadite (Ti/BAG) Bio-Composite Coatings via Laser Treatment

by Avneesh Kumar, Dhruva Kumar Goyal, Ravi Kant and Harpreet Singh

Coatings 2022, 12(7), 1010; https://doi.org/10.3390/coatings12071010 - 18 Jul 2022

Cited by 10 | Viewed by 2161

Abstract

This study aims to enhance the corrosion performance of cold-sprayed titanium/baghdadite (Ti/BAG) bio-composite coatings. Laser post processing was performed to reduce porosity and improve mechanical properties. The process parameters for laser treatment of cold-sprayed coatings were verified experimentally using scanning electron microscopy (SEM) [...] Read more.

This study aims to enhance the corrosion performance of cold-sprayed titanium/baghdadite (Ti/BAG) bio-composite coatings. Laser post processing was performed to reduce porosity and improve mechanical properties. The process parameters for laser treatment of cold-sprayed coatings were verified experimentally using scanning electron microscopy (SEM) and a thermal imaging camera. The laser-treated coatings are analyzed with SEM, energy-dispersive spectroscopy (EDS), ImageJ software, and X-ray diffraction (XRD). Furthermore, electrochemical analysis of the laser-treated and as-sprayed coatings was conducted in Ringer’s solution. The results of this study revealed that laser treatment helps significantly in enhancing resistance to corrosion for Ti/BAG composite coatings in a Ringer’s solution. The reduction in porosity and surface roughness is ascribed as the reason for their superior performance relative to as-sprayed coatings. Full article

(This article belongs to the Section Corrosion, Wear and Erosion)

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22 pages, 3934 KiB

Open AccessArticle

Study on Cold Recycled Asphalt Mixtures with Emulsified/Foamed Asphalt in the Laboratory and On-Site

by Haisheng Zhao, Jianming Su, Shijie Ma, Chunhua Su, Xiaoyan Wang, Zengguang Li, Jincheng Wei and Shiping Cui

Coatings 2022, 12(7), 1009; https://doi.org/10.3390/coatings12071009 - 18 Jul 2022

Cited by 10 | Viewed by 2566

Abstract

Millions of tons of reclaimed asphalt pavement (RAP) and reclaimed aggregate or reclaimed inorganic binder stabilized aggregate (RAI) is produced every year in China. The cold recycled mixture (CRM) technology reduces fuel consumption, emissions, and cost and utilizes the high content of RAP. [...] Read more.

Millions of tons of reclaimed asphalt pavement (RAP) and reclaimed aggregate or reclaimed inorganic binder stabilized aggregate (RAI) is produced every year in China. The cold recycled mixture (CRM) technology reduces fuel consumption, emissions, and cost and utilizes the high content of RAP. In this paper, six types of CRM with varying RAP/RAI composition and asphalt binders were investigated. The laboratory tests included strength indicators, high temperature stability, low temperature crack resistance, water stability, and dynamic modulus. A full-scale trial section was constructed after the laboratory tests. Except for low temperature failure strain without secondary compaction in the mixture design, test results illustrated that the performances of different CRMs met the specifications. The cement addition limited the thermo-viscoelastic behavior of the CRM. The RAI contents had reduced the water sensitivity of CRM, and the emulsified asphalt CRM had better performance than the foamed asphalt CRM. The performances of samples cored from the test section in the field met the specifications and were lower than that in the laboratory. The curing conditions in the field were not as effective as in the laboratory. The curing conditions and compaction method should simulate the conditions in the field to guide the CRM selection and mixture design. Full article

(This article belongs to the Section Surface Characterization, Deposition and Modification)

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11 pages, 4295 KiB

Open AccessArticle

Friction Properties of the Heat-Treated Electroless Ni Coatings Embedded with c-BN Nanoparticles

by Mara Kandeva, Mihail Zagorski, Ružica Nikolić, Blaža Stojanović, Adrian But, František Botko, Ján Piteľ and Aleksandar Vencl

Coatings 2022, 12(7), 1008; https://doi.org/10.3390/coatings12071008 - 18 Jul 2022

Cited by 7 | Viewed by 2194

Abstract

The nickel (Ni) coatings without and with embedded (5–7 vol. %) cubic boron nitride (c-BN) nanoparticles (10 nm in diameter) were deposited on carbon steel substrate by an electroless plating process. Coatings were tested in as-deposited and heat-treated (heating at 300 °C for [...] Read more.

The nickel (Ni) coatings without and with embedded (5–7 vol. %) cubic boron nitride (c-BN) nanoparticles (10 nm in diameter) were deposited on carbon steel substrate by an electroless plating process. Coatings were tested in as-deposited and heat-treated (heating at 300 °C for 6 h) conditions. Coating structure characterisation was performed, as well as hardness and roughness measurements. Friction properties were tested in dry and in water (seawater) lubricated contact conditions, with bronze as a counter-body material. Both static and kinetic coefficients of friction were measured for two different surface texture preparations (initial and working). The first surface texture simulated the running-in condition, and the second surface texture represented the steady-state conditions. The enhancement of the abrasive and erosive wear resistance of heat-treated electroless Ni coatings with embedded c-BN nanoparticles was already proved in our previous studies. This study aims to investigate those influences on friction properties of electroless Ni coatings in different sliding conditions. The results show that the coefficients of friction did not differ too much between the coatings and that the surface roughness and presence of seawater had a much stronger influence. Full article

(This article belongs to the Special Issue Quality Tools in the Design of Coatings)

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