Coatings

14 pages, 5392 KiB

Open AccessArticle

Effect of One Sulfate-Reducing Bacterium SRB-Z Isolated from Pearl River on the Corrosion Behavior of Q235 Carbon Steel

by Hong Qi, Qingshan Shi, Ruqun Peng, Tingli Sun, Zheng Zhang, Liangqiu Li and Xiaobao Xie

Coatings 2023, 13(2), 478; https://doi.org/10.3390/coatings13020478 - 20 Feb 2023

Cited by 2 | Viewed by 2055

Sulfate-reducing bacteria (SRB) have long been reported to participate in metal corrosion processes in anoxic environments. However, existing theories still need enrichment by identifying more corrosive microorganisms and exploring more plausible microbiologically-influenced corrosion pathways. In this study, a strain SRB-Z was isolated from [...] Read more.

Sulfate-reducing bacteria (SRB) have long been reported to participate in metal corrosion processes in anoxic environments. However, existing theories still need enrichment by identifying more corrosive microorganisms and exploring more plausible microbiologically-influenced corrosion pathways. In this study, a strain SRB-Z was isolated from the Pearl River in Guangzhou, and its effect and mechanisms on corrosion of Q235 carbon steel were examined. The biofilms, corrosion products, pits, and corrosion electrochemistry were characterized by SEM, XPS, CLSM, EDS, white light interferometer 3D profilometry, and electrochemical analysis, respectively. The results of this study indicate that SRB-Z could cause serious pitting of Q235 carbon steel. The maximum pit depth reached 54 μm after immersion corrosion for 7 days. Strain SRB-Z promoted the cathodic reaction rate of Q235. The relative analyses revealed that pitting corrosion occurred because of galvanic corrosion caused by the formation of an FeS-SRB/Fe galvanic couple under the synergistic effect of the SRB-Z biofilm and its metabolite (H₂S) on the Q235 coupon surfaces. Full article

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

► Show Figures

Graphical abstract

11 pages, 1695 KiB

Open AccessArticle

Silane-Containing Universal Adhesives Influence Resin-Ceramic Microtensile Bond Strength

by Mohamed M. Awad, Feras Alhalabi, Abdullah Alshehri, Mohammed Ali Salem, Ali Robaian, Shahad Alghannam, Abdullah S. Alayad, Basil Almutairi and Ali Alrahlah

Coatings 2023, 13(2), 477; https://doi.org/10.3390/coatings13020477 - 20 Feb 2023

Cited by 3 | Viewed by 2932

Abstract

Background: Silane-containing universal adhesives (UAs) are marketed as adhesion promotors for glass-ceramics. Objectives: This study aimed to evaluate the priming capacity of γ-methacryloxypropyltrimethoxysilane (γMPTS)-containing and γ-methacryloxypropyltriethoxysilane (γMPTES)/3-(aminopropyl)triethoxysilane (APTES)-containing universal adhesives (UAs) for lithium disilicate ceramic (LDC). Materials and Methods: Etched LDC discs were [...] Read more.

Background: Silane-containing universal adhesives (UAs) are marketed as adhesion promotors for glass-ceramics. Objectives: This study aimed to evaluate the priming capacity of γ-methacryloxypropyltrimethoxysilane (γMPTS)-containing and γ-methacryloxypropyltriethoxysilane (γMPTES)/3-(aminopropyl)triethoxysilane (APTES)-containing universal adhesives (UAs) for lithium disilicate ceramic (LDC). Materials and Methods: Etched LDC discs were distributed into four groups according to the priming material used: (control), no priming; (MBN), LDC was primed with a universal primer (Monobond N); (SBU), γMPTS-containing UA (Single Bond Universal Adhesive) was used as a primer; and (SBP), γMPTES/APTES-containing UA (Scotchbond Universal Plus Adhesive) was used as a primer. LDC discs were cemented using a dual-cure resin cement, then sectioned into microbeams for microtensile bond strength (μTBS) evaluation. Failure modes were assessed. Results: MBN application showed the highest μTBS among all groups. γMPTES/APTES-containing UA (SBP) resulted in considerably higher μTBS compared with γMPTS-containing UA (SBU) or the control group. The mixed failures were the most predominant among all groups. Conclusions: The effect of silane-containing UAs on resin-ceramic μTBS is material dependent. Although γMPTES/APTES-containing UA improved bonding to LDC, the priming of LDC with either of the UAs tested cannot be considered as an alternative to a separate silanization (priming) step using a universal primer. Full article

(This article belongs to the Special Issue Advanced Biomaterials, Coatings and Techniques: Applications in Medicine and Dentistry)

► Show Figures

Figure 1

10 pages, 9135 KiB

Open AccessArticle

Effect of the Welding Thermal Cycle on the Microstructure and Mechanical Properties of TiC Cermet HAZ Using the Gleeble Simulator

by Wei Wei, Zhiquan Huang, Haiyan Zhang and Shaokang Guan

Coatings 2023, 13(2), 476; https://doi.org/10.3390/coatings13020476 - 20 Feb 2023

Cited by 4 | Viewed by 1575

Abstract

The effect of heat input on the microstructure and mechanical properties of TiC cermet in MIG welding has been comprehensively investigated by Gleeble simulation. The microstructure, phase composition and shear fracture of TiC cermet were examined by OM (optical microscopy), SEM (scanning electron [...] Read more.

The effect of heat input on the microstructure and mechanical properties of TiC cermet in MIG welding has been comprehensively investigated by Gleeble simulation. The microstructure, phase composition and shear fracture of TiC cermet were examined by OM (optical microscopy), SEM (scanning electron microscope), TEM (transmission electron microscope) and XRD (X-ray diffraction) analyses. The results show that the heat input has a significant effect on the properties of TiC cermet. With TiC particles and the austenite bonding phase remaining the same, the heat input can effectively improve the toughness of the bonding phase and the structural strength from 219.9 HV_0.01 to 380.5 HV_0.01 and from 469 MPa to 684 MPa, respectively, as the dislocation density increases while the heat input increases. When the heat input is 3.4 KJ/cm, the shear strength reaches the peak at 684 MPa, with the increase in heat input, the secondary fragmentation of TiC particles increases, and the crack propagation leads to a significant decrease in material strength. Full article

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

► Show Figures

Figure 1

13 pages, 6576 KiB

Open AccessArticle

Enhanced Performance in Si₃N₄ Ceramics Cutting Tool Materials by Tailoring of Phase Composition and Hot-Pressing Temperature

by Shuai Guo, Fusheng Zhu, Zhimeng Xiu, Mu Zhang and Xudong Sun

Coatings 2023, 13(2), 475; https://doi.org/10.3390/coatings13020475 - 20 Feb 2023

Cited by 4 | Viewed by 2318

Abstract

In this study, a type of micro-nano Si₃N₄ matrix ceramic cutting tool material was successfully prepared by controlling the addition amount of TiC_0.7N_0.3 and the hot-pressing sintering temperature. The effects of different volume fractions of TiC_0.7 [...] Read more.

In this study, a type of micro-nano Si₃N₄ matrix ceramic cutting tool material was successfully prepared by controlling the addition amount of TiC_0.7N_0.3 and the hot-pressing sintering temperature. The effects of different volume fractions of TiC_0.7N_0.3 on the microstructure, mechanical properties, particle size distribution, and relative density of Si₃N₄ ceramic tools at the same temperature were investigated. The results show that the addition of TiC_0.7N_0.3 makes the β-Si₃N₄ grains with different diameters and aspect ratios interlaced and tightly bonded, thus achieving the strengthening and toughening effects. In addition, the effects of different hot-press sintering temperatures on the properties of Si₃N₄ ceramic tool materials were studied. It was concluded that the density of the material increased with the increase of the hot-pressing temperature. The relative density, flexural strength, and fracture toughness of the samples with 1 vol% TiC_0.7N_0.3 added at 1750 °C and 30 MPa pressure reached 99.22%, 993 MPa, and 9.81 MPa·m^1/2, respectively. Full article

(This article belongs to the Special Issue Ceramic Films and Coatings: Properties and Applications)

► Show Figures

Figure 1

18 pages, 3199 KiB

Open AccessArticle

Study on the Influence Factors of Dynamic Modulus and Phase Angle of Dense Gradation Polyurethane Mixture

by Haisheng Zhao, Wensheng Zhang, Shiping Cui, Shijie Ma, Baoji Miao, Enzhou Di, Xiaoyan Wang, Chunhua Su, Jincheng Wei and Shan Liu

Coatings 2023, 13(2), 474; https://doi.org/10.3390/coatings13020474 - 19 Feb 2023

Cited by 5 | Viewed by 1735

Abstract

Polyurethane (PU) mixture is a new pavement material with excellent pavement performance, and most research was focused on the enhancement of pavement performance, but rarely on the dynamic property. This paper studied the factors including gradation, aggregate type, PU type, and PU content, [...] Read more.

Polyurethane (PU) mixture is a new pavement material with excellent pavement performance, and most research was focused on the enhancement of pavement performance, but rarely on the dynamic property. This paper studied the factors including gradation, aggregate type, PU type, and PU content, which may influence the dynamic property of the PU mixture. Test results showed that the PU mixture is a kind of linear viscoelastic material, its dynamic modulus and phase angle changed with test temperature and loading frequency, the dynamic modulus would drop by 40%~50% with the temperature raised from 5 °C to 55 °C. All of the factors could affect the dynamic property of the PU mixture which was proved by the analysis of covariance. The effect of gradation did not change with the increase of the nominal maximum aggregate size (NMAS), the dynamic modulus of the PU mixture with limestone was higher than that of the PU mixture with basalt, and the curing speed of PU could affect the ultimate stiffness of the PU mixture, and the increase of the PU content did not help in the increase of the dynamic modulus of the PU mixture. So, more consideration about the selection of gradation, aggregate type, PU type, and PU content should be taken into the design of the PU mixture, which could produce the best pavement structure combination and save more investment. Full article

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

► Show Figures

Figure 1

14 pages, 3358 KiB

Open AccessArticle

UV-Activated, Transparent Oxygen Scavenger Coating Based on Inorganic–Organic Hybrid Polymer (ORMOCER^®) with High Oxygen Absorption Capacity

by Sabine Amberg-Schwab, Kajetan Müller, Ferdinand Somorowsky and Sven Sängerlaub

Coatings 2023, 13(2), 473; https://doi.org/10.3390/coatings13020473 - 19 Feb 2023

Cited by 2 | Viewed by 2904

Abstract

Oxygen scavengers are used to reduce the oxygen permeation of packaging (active barrier) and to absorb oxygen from its direct environment, e.g., a headspace of packaged food. Few oxygen scavenger coatings have been developed. Therefore, in this study, a novel oxygen scavenger coating [...] Read more.

Oxygen scavengers are used to reduce the oxygen permeation of packaging (active barrier) and to absorb oxygen from its direct environment, e.g., a headspace of packaged food. Few oxygen scavenger coatings have been developed. Therefore, in this study, a novel oxygen scavenger coating has been developed. It is based on inorganic–organic polymers (ORMOCER^®). The oxygen absorption reaction is activated by UV light. The scavenger was synthesized, coated on aluminum foil, subsequently dried and afterwards laminated with a polyethylene sealing layer. UV light activates the oxygen scavenging reaction. The oxygen absorption capacity, measured at 23 °C and 0% r.h., was 242 ± 8 mg oxygen/g scavenger coating. When the oxygen scavenger coating layer was laminated by using a two-component polyurethane laminating adhesive, the absorption capacity was hardly reduced, with a measured absorption capacity of 223 ± 18 mg oxygen/g scavenger coating. In an experimental packaging sample with the oxygen scavenger coating with a thickness (dry) of 3 µm and 18 µm, near-zero mbar oxygen partial pressure was reached by the non-laminated oxygen scavenger coatings within two days, and within about 20 days when laminated with a polyurethane laminating adhesive and a PE-layer on the oxygen scavenger layer. The oxygen partial pressure was kept near zero mbar for 500 days, whereas in the experimental packaging without oxygen scavenger, the oxygen partial pressure increased to 110 mbar during this time. The developed oxygen scavenger based on inorganic–organic polymers can be applied as wet chemical coating on various surfaces with standard application procedures. Application scenarios are oxygen-sensitive goods such as food, pharmaceutical products and cosmetics. Full article

(This article belongs to the Section Functional Polymer Coatings and Films)

► Show Figures

Graphical abstract

16 pages, 4595 KiB

Open AccessArticle

Studies of New Layer Formation on the Surface of Zinc Doped Hydroxyapatite/Chitosan Composite Coatings in Biological Medium

by Mikael Motelica-Heino, Mihai Valentin Predoi, Steluta Carmen Ciobanu, Simona Liliana Iconaru and Daniela Predoi

Coatings 2023, 13(2), 472; https://doi.org/10.3390/coatings13020472 - 19 Feb 2023

Cited by 11 | Viewed by 1794

Abstract

Usually, before being used in biomedical applications, a biomaterials’ bioactivity is tested by in vitro methods that simulate similar conditions to those found in the human body. In this work, we report on the synthesis of zinc-doped hydroxyapatite–chitosan (ZnHApC) composite coatings by the [...] Read more.

Usually, before being used in biomedical applications, a biomaterials’ bioactivity is tested by in vitro methods that simulate similar conditions to those found in the human body. In this work, we report on the synthesis of zinc-doped hydroxyapatite–chitosan (ZnHApC) composite coatings by the vacuum deposition method. The surface microstructure and the chemical and molecular modification of the coatings before and after soaking in DMEM (Dulbecco’s Modified Eagle’s Medium) were studied. For this objective, techniques such as attenuated total reflection (ATR), Fourier transform infrared (FTIR) spectroscopy, metallographic microscopy (MM), and scanning electron microscopy (SEM) were applied used. Also, water contact angle measurements and swelling studies were made on ZnHApC composite coatings before and after soaking in a biological medium. The coatings’ adherence to the substrate was also studied. The results of antifungal studies on ZnHApC composite coatings against the Candida albicans microbial strain reveal their good antifungal activity. The biocompatibility of the composite coatings was tested using a primary osteoblast cell line. Our results suggest that zinc-doped hydroxyapatite–chitosan samples could be used as a bioimplant material due to their enhanced bioactivity and biocompatibility. Full article

(This article belongs to the Special Issue Toward Sustainability through Bio-Based Materials at the Interfaces with Living Systems)

► Show Figures

Figure 1

14 pages, 3105 KiB

Open AccessArticle

The Role of Water Hydrogen Bonds in the Formation of Associates and Condensates in Dispersions of Serum Albumin with Shungite Carbon and Quartz Nanoparticles

by Sergey Rozhkov, Andrey Goryunov, Vladimir Kolodey, Lyubov Pron’kina and Natalia Rozhkova

Coatings 2023, 13(2), 471; https://doi.org/10.3390/coatings13020471 - 19 Feb 2023

Cited by 3 | Viewed by 1897

Abstract

The role of the network of water hydrogen bonds in the regulation of the intermolecular interaction’s responsible for colloidal stability of dispersions has been studied in order to search for general patterns of interaction between water, nanoparticles, and bio-macromolecules. Raman spectroscopy for mixed [...] Read more.

The role of the network of water hydrogen bonds in the regulation of the intermolecular interaction’s responsible for colloidal stability of dispersions has been studied in order to search for general patterns of interaction between water, nanoparticles, and bio-macromolecules. Raman spectroscopy for mixed dispersions of bovine serum albumin (SA), shungite carbon nanoparticles (ShC NPs), and quartz nanoparticles (quartz NPs) was performed within the wave number range 3200–3600 cm⁻¹. The main spectral lines in this range are caused by the OH stretch vibrations of water molecules. We analyzed the state of the water hydrogen bonding network for dispersions of varied ratios of both fatty acid-containing and fatty acid-free SA macromolecules, ShC NPs, and silica NPs in the range 0.01–10 mg/mL.We used dynamic light scattering to control the sizes of the protein associates and protein associates with ShC NPs and quartz NPs. The strength of the hydrogen bonds in water depends essentially non-linearly, but in a qualitatively similar way, on the concentrations of the dispersion components. The initial strengthening of the bonds is followed by their loosening with a further increase in the concentration of the components. This is accompanied by the association of the dispersion components. We estimate the thickness of the protein corona layer as 20–25 nm for ShC NPs and 28–33 nm for quartz NPs, depending on the SA concentration. Colloidal stability of the aqueous dispersion is determined almost completely by an association of the protein with NPs. In contrast, colloidal stability of a pure protein solution is regulated by the formation of protein clusters of two main types and sizes. The association effects of SA with ShC NPs are evident in microscopic images of condensate films. The structures differ significantly for native and fatty acid-free SA in shape and size. Full article

(This article belongs to the Special Issue Perspective Coatings for Optical Materials Modifications)

► Show Figures

Graphical abstract

20 pages, 4827 KiB

Open AccessArticle

Improving the Surface Properties of an API 5L Grade B Pipeline Steel by Applying the Boriding Process—Part II: On the Changes in the Mechanical Properties

by Laura Montserrat Alcantar-Martínez, Pablo Alfredo Ruiz-Trabolsi, Raúl Tadeo-Rosas, José Guadalupe Miranda-Hernández, Román Cabrera-Sierra, Julio César Velázquez and Enrique Hernández-Sánchez

Coatings 2023, 13(2), 470; https://doi.org/10.3390/coatings13020470 - 18 Feb 2023

Cited by 5 | Viewed by 2427

Abstract

The mechanical performance of API 5L grade B steel, after undergoing a thermochemical boriding process, was assessed. We quantified the boride layer microhardness over cross-section specimens, with the aim of characterizing the mechanical resistance under different conditions. The pipeline steel was analyzed because [...] Read more.

The mechanical performance of API 5L grade B steel, after undergoing a thermochemical boriding process, was assessed. We quantified the boride layer microhardness over cross-section specimens, with the aim of characterizing the mechanical resistance under different conditions. The pipeline steel was analyzed because of the changes in yield strength, ultimate tensile strength, and ductility after treatment with boron. These oil and gas pipelines must work in aggressive environments, so borided pipeline steel specimens were tested to assess their erosion–corrosion resistance. Another important characteristic to evaluate was the wearing resistance, because the pipelines tend to suffer scratches when they are under construction. We also present a discussion of the results of the total research work (Part I and Part II), including the results of the boride layer characterization as well as the changes in the substrate, with the goal of selecting the best conditions under which to treat pipeline steel. More extreme treatment conditions can help to form more stable and resistant boride layers, but they can considerably modify some mechanical characteristics of the API 5L grade B steel. For this reason, the boriding treatment conditions must be chosen in a synergistic way. Full article

(This article belongs to the Topic Materials and Surface Treatment Processes Used for Engineering Applications)

► Show Figures

Figure 1

17 pages, 8096 KiB

Open AccessArticle

Influence of TiC Addition on Corrosion and Tribocorrosion Resistance of Cr₂Ti-NiAl Electrospark Coatings

by Konstantin A. Kuptsov, Mariya N. Antonyuk, Alexander N. Sheveyko, Andrey V. Bondarev and Dmitry V. Shtansky

Coatings 2023, 13(2), 469; https://doi.org/10.3390/coatings13020469 - 18 Feb 2023

Cited by 1 | Viewed by 1964

Abstract

Marine and coastal infrastructures usually suffer from synergetic effect of corrosion and wear known as tribocorrosion, which imposes strict requirements on the structural materials used. To overcome this problem, novel composite wear- and corrosion-resistant xTiC-Fe-CrTiNiAl coatings with different TiC content were successfully developed. [...] Read more.

Marine and coastal infrastructures usually suffer from synergetic effect of corrosion and wear known as tribocorrosion, which imposes strict requirements on the structural materials used. To overcome this problem, novel composite wear- and corrosion-resistant xTiC-Fe-CrTiNiAl coatings with different TiC content were successfully developed. The coatings were obtained by the original technology of electrospark deposition in a vacuum using xTiC-Cr₂Ti-NiAl (x = 0, 25, 50, 75%) electrodes. The structure and morphology of the coatings were studied in detail by XRD, SEM, and TEM. The effect of TiC content on the tribocorrosion behavior of the coatings was estimated using tribological and electrochemical (under stationary and wear conditions) experiments, as well as impact testing, in artificial seawater. The TiC-free Fe-Cr₂Ti-NiAl coating revealed a defective inhomogeneous structure with transverse and longitudinal cracks. Introduction of TiC allowed us to obtain coatings with a dense structure without visible defects and with uniformly distributed carbide grains. The TiC-containing coatings were characterized by a hardness and elastic modulus of up to 10.3 and 158 GPa, respectively. Formation of a composite structure with a heavily alloyed corrosion-resistant matrix based on α-(Fe,Cr) solid solution and uniformly distributed TiC grains led to a significant increase in resistance to stationary corrosion and tribocorrosion in artificial seawater. The best 75TiC-Fe-CrTiNiAl coating demonstrated the lowest corrosion current density values both under stationary (0.03 μA/cm²) and friction conditions (0.8 μA/cm²), and was characterized by both a 2-2.5 times lower wear rate (4 × 10⁻⁶ mm³/Nm) compared to AISI 420S steel and 25TiC-Fe-CrTiNiAl and a high fracture toughness. Full article

(This article belongs to the Special Issue Advanced Nano-Structured Hard Coatings: Design, Synthesis, and Applications)

► Show Figures

Figure 1

12 pages, 4959 KiB

Open AccessArticle

The Study of Surface Structure and the Tribological Property of DLC-Modified NBR Elastomers Using DC-MS

by Chuang Wang, Can Xu, Zhiyu Wu and Feng Wen

Coatings 2023, 13(2), 468; https://doi.org/10.3390/coatings13020468 - 18 Feb 2023

Cited by 3 | Viewed by 1603

Abstract

The DLC film was prepared on a nitrile rubber (NBR) elastomer by DC magnetron sputtering (DC-MS), and the sp³ ratio of the DLC film was adjusted by changing the negative bias voltage applied to the substrate. The microstructure, composition, and tribological properties [...] Read more.

The DLC film was prepared on a nitrile rubber (NBR) elastomer by DC magnetron sputtering (DC-MS), and the sp³ ratio of the DLC film was adjusted by changing the negative bias voltage applied to the substrate. The microstructure, composition, and tribological properties of the DLC films deposited on NBR substrates were systematically investigated. The results reveal that the DLC film on the NBR surface can protect the NBR and reduce the surface roughness of the NBR. While the bias voltage ranges from 0 V to −150 V, the content of sp³ increases with an increase in the negative bias voltage. The viscoelasticity and roughness of the NBR substrate will greatly affect the DLC film’s adhesion strength and tribological behavior. Full article

(This article belongs to the Special Issue Thermal and Mechanical Properties of Polymer Based Materials and Adhesives)

► Show Figures

Figure 1

5 pages, 214 KiB

Open AccessEditorial

Special Issue “Advanced Coating Technology by Physical Vapor Deposition and Applications”

by Chuen-Lin Tien

Coatings 2023, 13(2), 467; https://doi.org/10.3390/coatings13020467 - 18 Feb 2023

Cited by 9 | Viewed by 3684

Abstract

Coating technology covers a wide range of fields [...] Full article

(This article belongs to the Special Issue Advanced Coating Technology by Physical Vapor Deposition and Applications)

11 pages, 3140 KiB

Open AccessArticle

Wear Behavior of Monolithic Zirconia after Staining, Glazing, and Polishing Opposing Dental Restorative Materials: An In Vitro Study

by Lívia Fiorin, Paulo Eduardo Barros Souza Oliveira, Allan Oliveira da Silva, Adriana Cláudia Lapria Faria, Ana Paula Macedo, Ricardo Faria Ribeiro and Renata Cristina Silveira Rodrigues

Coatings 2023, 13(2), 466; https://doi.org/10.3390/coatings13020466 - 18 Feb 2023

Cited by 4 | Viewed by 2192

Abstract

The purpose of this in vitro study was to compare the effect of staining, glazing, and polishing on the wear behavior of stabilized zirconia with 5 mol% of yttrium oxide (5Y-TZP) opposing 5Y-TZP, leucite-reinforced ceramic (LC), lithium disilicate (LD), and microhybrid composite resin [...] Read more.

The purpose of this in vitro study was to compare the effect of staining, glazing, and polishing on the wear behavior of stabilized zirconia with 5 mol% of yttrium oxide (5Y-TZP) opposing 5Y-TZP, leucite-reinforced ceramic (LC), lithium disilicate (LD), and microhybrid composite resin (MCR). Hemispheres of 5Y-TZP were divided into six groups (n = 10) according to the finishing procedure: C (control), S (staining), G (glazing), P (polishings), SG (staining plus glazing), and SP (staining plus polishing). The two-body wear test (2BW) was performed (20 N load, at 2 Hz, until 300,000 cycles). Vertical height loss of hemispheres (VHL) and wear depth of restorative materials (WD) were analyzed using a profile projector and laser confocal microscope, respectively. Data of VHL and WD were analyzed using a generalized linear model by the Wald test and t post hoc test with the Bonferroni adjustment (α = 0.05). The staining, glazing, polishing, and restorative material had a significant effect (p < 0.05) on VHL and WD. Polishing reduced VHL opposing MCR, LC, and LD. There was an increase in WD to G opposing LD and SG opposing MCR. The 5Y-TZP presented the highest wear resistance, while MCR presented the lowest. Polishing was recommended to promote staining durability and decrease wear rates opposing MCR and LD. Full article

(This article belongs to the Section Bioactive Coatings and Biointerfaces)

► Show Figures

Figure 1

10 pages, 1709 KiB

Open AccessArticle

Blends of Chitosan and Water Kefir Grain Biomass Incorporated with Nanosilica

by Carolina Oliveira Marinho, Luís Marangoni Júnior, Ricardo Rodrigo Ramos Cecci and Roniérik Pioli Vieira

Coatings 2023, 13(2), 465; https://doi.org/10.3390/coatings13020465 - 18 Feb 2023

Cited by 2 | Viewed by 1685

Abstract

The use of by-products from the food industry for the development of bioplastics represents an outstanding strategy in meeting current demands for material circularity. In this work, films based on chitosan (CH) and water kefir grain (WKG) biomass incorporated with different concentrations (3%–10% [...] Read more.

The use of by-products from the food industry for the development of bioplastics represents an outstanding strategy in meeting current demands for material circularity. In this work, films based on chitosan (CH) and water kefir grain (WKG) biomass incorporated with different concentrations (3%–10% w/w) of nanosilica (SiO₂) were developed for the first time. The key properties required for food packaging were assessed. There are no structural changes (FT-IR) upon nanosilica incorporation. However, the XRD analysis indicates a tendency toward an increase in the amorphous character of the films. For the films with higher proportions of nanosilica, the SEM images indicate particle agglomeration points. The control film (CH/WKG) experienced a 5% mass loss at 68.3 °C, while the CH/WKG10%SiO₂ film showed the same mass reduction at 75.7 °C, indicating the nanoparticles increased the moisture-associated thermal stability of the films. The tensile strength was not significantly influenced by the incorporation of nanosilica, but there was an increase in elongation at break, from 25.01 ± 3.67% (CH/WKG) to 40.72 ± 4.89% (CH/WKG/3%SiO₂), followed by a drastic reduction to 9.10 ± 1.99% (CH/WKG/10%SiO₂). Overall, 3% of SiO₂ may be the most promising concentration for CH/WKG blends in future application as sustainable alternatives for food packaging, since it is possible to improve properties, such as ductility and thermal stability, at this concentration without marked losses in the tensile strength of the films. Full article

(This article belongs to the Special Issue Research on Food Packaging and Storage)

► Show Figures

Figure 1

14 pages, 2141 KiB

Open AccessArticle

Hybrid Organic/Inorganic Piezoelectric Device for Energy Harvesting and Sensing Applications

by Mariya Aleksandrova, Liliya Tudzharska, Krasimir Nedelchev and Ivan Kralov

Coatings 2023, 13(2), 464; https://doi.org/10.3390/coatings13020464 - 18 Feb 2023

Cited by 5 | Viewed by 1963

Abstract

Novel hybrid organic/inorganic flexible devices with composite films, consisting of Ba_0.5Sr_0.5TiO₃ (BST), were prepared by inserting BST nanocoating under spray deposited Poly-vinylidene fluoride-based co-polymer PVDF-TrFE. The study validated that the crystalline structure of BST remains unaffected by the [...] Read more.

Novel hybrid organic/inorganic flexible devices with composite films, consisting of Ba_0.5Sr_0.5TiO₃ (BST), were prepared by inserting BST nanocoating under spray deposited Poly-vinylidene fluoride-based co-polymer PVDF-TrFE. The study validated that the crystalline structure of BST remains unaffected by the presence of polymer. The 3D atomic force microscopic image of the composite sample confirmed the improved surface roughness and contact conditions after spraying the polymer. As a result, the hybrid sample exhibited a higher polarization current with reduced impedance and parasitic inductance. The enhancement of the stability of the piezoelectric parameters at multiple bending was observed for the hybrid sample in comparison with the BST single film transducer. The drop of the root mean square (RMS) voltage was 70% after approximately 340,000 numbers of bending against less than 3% for the hybrid BST+PVDF-TrFE device. Due to the effect of the separate layers and summed net charges, the piezoelectric voltage of the hybrid device was competitive to the piezoelectric oxide films, despite the lower piezoelectric coefficient of the polymer. The proposed solution paves the path toward lead-free, wearable energy harvesting devices for low-power consuming electronic devices. Full article

► Show Figures

Figure 1

11 pages, 3966 KiB

Open AccessArticle

Study on Sintering Behavior of Reaction-Cured Glass Coating

by Mingwei Li, Yulei Sun, Gang Zeng, Wenhao Li, Yesheng Zhong, Liping Shi, Rongguo Wang and Xiaodong He

Coatings 2023, 13(2), 463; https://doi.org/10.3390/coatings13020463 - 17 Feb 2023

Cited by 1 | Viewed by 1991

Abstract

High-emissivity coatings constitute an essential component of reusable thermal protection systems, determining the success or failure of hypersonic spacecraft. Reaction-cured glass coating is the basis for all current high-emissivity coatings, and the study of its sintering behavior is of great scientific significance for [...] Read more.

High-emissivity coatings constitute an essential component of reusable thermal protection systems, determining the success or failure of hypersonic spacecraft. Reaction-cured glass coating is the basis for all current high-emissivity coatings, and the study of its sintering behavior is of great scientific significance for the development and performance enhancement of the coating. Microstructures and phase compositions of the samples before and after the sintering process were determined using SEM, XRD, and EDS. The sintering temperature, inserting temperature, and heating rate were systematically investigated. The results show that the effects of the sintering temperature, inserting temperature, and heating rate on the coating occur in decreasing order. The optimum condition for coating sintering in this study is an insertion temperature of 1100 °C, a heating rate of 10 °C/min, and a sintering temperature of 1200 °C, and a crack-free and containing SiB₄ borosilicate glass coating was successfully prepared. Full article

(This article belongs to the Special Issue Fabrication, Properties Characterization and Application of Thermal Protective Coatings)

► Show Figures

Figure 1

13 pages, 4102 KiB

Open AccessArticle

Improvement of Textile Materials Processing Techniques by Applying Aqueous Dispersions of Polymers

by Luidmila Petrova, Rodion Grishin, Anvar Zimnurov, Olga Kozlova, Olga Odintsova and Elena Sangeeva

Coatings 2023, 13(2), 462; https://doi.org/10.3390/coatings13020462 - 17 Feb 2023

Viewed by 2424

Abstract

This paper presents the results of studies in the field of polymer materials application for fabric modification. The aim of the study is to identify the most effective technique of deposition of Russian-made formulations of an acryl and urethane nature with pigment compositions [...] Read more.

This paper presents the results of studies in the field of polymer materials application for fabric modification. The aim of the study is to identify the most effective technique of deposition of Russian-made formulations of an acryl and urethane nature with pigment compositions in the processes of functional fabric production. The authors analyze the efficiency of three processing solutions: the technology of uniform dyeing with pigments consisting of coating the fabric surface with a pigment–polymer composition, the technology of obtaining “camouflage” fabrics based on a conceptually new approach to creating the IR-remission effect on printed fabrics, and the technology of creating a stable retro-reflective effect on a fabric through the use of polymers produced in Russia. The paper also shows the conceptual differences in the pigment distribution mechanisms in the fiber or in the polymer matrix depending on the technique of fabric coating. The cheapest and safest technique for the environment is the squeegee method of pigment application, which provides fabrics with both oil- and water-repellent properties. An innovative technology has been developed based on the squeegee method for achieving the IR-remission effect on fabrics with “camouflage” patterns. A series of physico–chemical tests (spectrophotometry, electron microscopy), as well as assessment of the consumer properties of the obtained textile materials confirmed the efficiency of using aqueous dispersions of acrylic polymers made in Russia for producing competitive functional fabrics. Full article

(This article belongs to the Special Issue Efficiency of Coatings Formed in Various Ways)

► Show Figures

Figure 1

16 pages, 3709 KiB

Open AccessEditor’s ChoiceArticle

Enhanced Optically–Excited THz Wave Emission by GaAs Coated with a Rough ITO Thin Film

by Anup Kumar Sahoo, Shi-Ying Kang, Peichen Yu and Ci-Ling Pan

Coatings 2023, 13(2), 461; https://doi.org/10.3390/coatings13020461 - 17 Feb 2023

Cited by 3 | Viewed by 2136

Abstract

In this study, we report enhancement of terahertz (THz) radiation with indium-tin-oxide (ITO) thin-film deposited on semi-insulating gallium arsenide substrate (SI-GaAs). The amplitude of THz emission from both ITO/SI-GaAs and bare SI-GaAs substrate as a function of optical pump (i) incident angle, (ii) [...] Read more.

In this study, we report enhancement of terahertz (THz) radiation with indium-tin-oxide (ITO) thin-film deposited on semi-insulating gallium arsenide substrate (SI-GaAs). The amplitude of THz emission from both ITO/SI-GaAs and bare SI-GaAs substrate as a function of optical pump (i) incident angle, (ii) polarization angle, and (iii) power were investigated. The enhancement of peak amplitude of a THz pulse transmitted through the ITO/SI-GaAs sample in comparison to bare SI-GaAs substrate varied from 100% to 0% when the pump incidence angle changed from 0° to 50°. The maximum enhancement ratio of peak amplitude for a coated sample relative to the bare substrate is approximately up to 2.5 times at the minimum pump intensity of 3.6 TW/m² and gradually decreased to one at the maximum pump intensity of 20 TW/m². From outcomes of these studies, together with data on surface and material characterization of the samples, we show that THz emission originates from the ITO/GaAs interfaces. Further, both interface-field-induced transient current and field-induced optical rectification contribute to the observed THz signal. Observed enhancement was tentatively attributed to surface-plasmon-induced local field enhancement, coupled with constructive interference of forward and retro-reflected backward THz emission from the ITO/GaAs interfaces. The polarity-flip reported previously for very thin Au-coated GaAs was not observed. This was explained by the wide-bandgap, transparency and lower free carriers of ITO. For best results, the incident angle should be in the range of 0 to 30° and the incident polarization should be 0 to 45°. We further predict that the ITO thin film of suitable thickness or with engineered nanostructures, post-annealed under optimum conditions may lead to further enhancement of THz radiation from ITO-coated semiconductor surfaces. Full article

(This article belongs to the Special Issue New Advances in Novel Optical Materials and Devices)

► Show Figures

Figure 1

10 pages, 1825 KiB

Open AccessFeature PaperArticle

Pullulan/Agar-Based Functional Film Containing Eucalyptus Essential Oil and Rutin

by Swarup Roy and Jong-Whan Rhim

Coatings 2023, 13(2), 460; https://doi.org/10.3390/coatings13020460 - 17 Feb 2023

Cited by 8 | Viewed by 2391

Abstract

Biopolymer-based films were developed using a mixture of pullulan and agar, and the fabricated film was functionalized with bioactive functional components, Pickering emulsion of eucalyptus essential oil (PEU), and rutin. The color of the film with PEU and rutin supplemented was light yellow. [...] Read more.

Biopolymer-based films were developed using a mixture of pullulan and agar, and the fabricated film was functionalized with bioactive functional components, Pickering emulsion of eucalyptus essential oil (PEU), and rutin. The color of the film with PEU and rutin supplemented was light yellow. As a result, the yellowness index increased while the whiteness index of the film reduced. The functional filler showed a biocompatibility with the pullulan/agar polymer matrix. The presence of bioactive functional materials enhanced the UV protection properties of the film. The films’ mechanical properties, vapor barrier properties, and thermal stability were not pointedly affected by the presence of essential oils and rutin alone or in combination. The presence of essential oils and rutin markedly enhanced the antioxidant activity of pullulan/agar-based films. Therefore, the bioactive functional film developed can be useful for active food packaging applications. Full article

(This article belongs to the Special Issue Novel Trends and Emerging Technologies in Green Coatings and Packaging Materials)

► Show Figures

Graphical abstract

22 pages, 10564 KiB

Open AccessFeature PaperArticle

Reactive Sputtering Process Study for Vanadium Oxynitride Films

by Nai Yun Chang, Chuan Li and Jang-Hsing Hsieh

Coatings 2023, 13(2), 459; https://doi.org/10.3390/coatings13020459 - 17 Feb 2023

Cited by 2 | Viewed by 2230

Abstract

In this study, vanadium oxynitride thin films were deposited by reactive magnetron sputtering using pure vanadium targets, Ar as a plasma carrier, and a mix of N₂ and O₂ as reactive gases. Various ratios of mass flow rates between two reactive [...] Read more.

In this study, vanadium oxynitride thin films were deposited by reactive magnetron sputtering using pure vanadium targets, Ar as a plasma carrier, and a mix of N₂ and O₂ as reactive gases. Various ratios of mass flow rates between two reactive gases were maintained as a constant during the process. To obtain crystalline phases of oxynitrides, rapid thermal annealing in Ar atmosphere at 600 °C and 700 °C for 5 min was conducted after the deposition. This study aims to define the range of the process parameters of magnetron sputtering to deposit vanadium oxynitride thin films. The assessment for the characterization of films utilizes the surface profiler, scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, four-point probe, Hall analyzer, and UV-visible-NIR spectrometer. Experimental results reveal that the annealed films can be oxynitrides when the oxygen flow rate is below 0.25 sccm, and the ratio of oxygen/nitrogen is no more than ~1/10. The annealed vanadium oxynitride films, in terms of their properties, are closer to vanadium nitrides than to oxides, due to the intended low supply of oxygen during deposition. For instance, the film is more metallic than semi-conductive with dark appurtenance and high optical absorbance across the spectrum between 200 and 900 nm. For practical purposes, the deposition conditions of O₂:N₂ = 1/20, O₂ < 0.25 sccm, and 600 °C annealing are recommended to obtain vanadium oxynitride films with relatively lower resistivity (10⁻² Ω cm) and optical transmittance (<15%) through films. Full article

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

► Show Figures

Figure 1

16 pages, 6609 KiB

Open AccessArticle

Experimental Study on the Bending Resistance of Hollow Slab Beams Strengthened with Prestressed Steel Strand Polyurethane Cement Composite

by Jin Li, Yongshu Cui, Dalu Xiong, Zhongmei Lu, Xu Dong, Hongguang Zhang, Fengkun Cui and Tiancheng Zhou

Coatings 2023, 13(2), 458; https://doi.org/10.3390/coatings13020458 - 17 Feb 2023

Cited by 2 | Viewed by 1305

Abstract

In order to explore the toughening performance and failure mechanism of hollow slab beams strengthened with prestressed steel strand polyurethane cement composite, three test beams (L1–L3) were strengthened and one test beam (L0) was used as a comparison. The influence of different tensile [...] Read more.

In order to explore the toughening performance and failure mechanism of hollow slab beams strengthened with prestressed steel strand polyurethane cement composite, three test beams (L1–L3) were strengthened and one test beam (L0) was used as a comparison. The influence of different tensile stresses of steel strand and fiber additions on the flexural bearing capacity of the hollow slab beams, was studied. The cracking characteristics, load deflection relationship, ductility and strain of each test beam were compared and analyzed. The test results showed that the toughened material was well bonded to the hollow slab beam and the steel strand, which effectively inhibited the development of cracks in the test beams. The flexural bearing capacity of the strengthened test beams was significantly improved. The use of prestressed steel strand polyurethane cement composite material effectively improved the flexural bearing capacity of the test beams, and this reinforcement process can be further extended to engineering applications. Full article

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

► Show Figures

Figure 1

5 pages, 228 KiB

Open AccessEditorial

Heritage Conservation and Restoration: Surface Characterization, Cleaning and Treatments

by Maduka L. Weththimuni and Maurizio Licchelli

Coatings 2023, 13(2), 457; https://doi.org/10.3390/coatings13020457 - 17 Feb 2023

Cited by 9 | Viewed by 2318

Abstract

Conservation is not the same thing as restoration [...] Full article

(This article belongs to the Special Issue Heritage Conservation and Restoration: Surface Characterization, Cleaning and Treatments)

9 pages, 2996 KiB

Open AccessArticle

pH-Sensitive Fluorescence Emission of Boron/Nitrogen Co-Doped Carbon Quantum Dots

by Oguzhan Ustun, Sugra Naz Karadag, Hayrunnisa Mazlumoglu, Asli Yilmaz and Mehmet Yilmaz

Coatings 2023, 13(2), 456; https://doi.org/10.3390/coatings13020456 - 17 Feb 2023

Cited by 3 | Viewed by 2433

Abstract

Carbon quantum dots (CQDs) with their strong photoluminescence (PL) activity, high biocompatibility, robust stability, low cytotoxicity, and flexible surface structures have been employed in many fields including chemical sensing, biosensing, photocatalyst, energy storage, and biomedical applications. Of note, CQDs present an intrinsic pH-sensitive [...] Read more.

Carbon quantum dots (CQDs) with their strong photoluminescence (PL) activity, high biocompatibility, robust stability, low cytotoxicity, and flexible surface structures have been employed in many fields including chemical sensing, biosensing, photocatalyst, energy storage, and biomedical applications. Of note, CQDs present an intrinsic pH-sensitive PL nature indicating their intense potential for pH-mediated sensing and imaging. Despite the numerous studies performed in the last two decades, the pH-sensitive PL mechanism of CQDs is still under debate and must be clarified to overcome the limitations in practical applications. Therefore, in this report, we performed a systematical study to determine the pH-sensitive PL nature of boron/nitrogen co-doped CQDs (B/N CQDs). In the first part, B/N CQDs with a strong blue emission were fabricated via a hydrothermal synthesis procedure. B/N-CQDs showed a strong blue PL emission with high quantum yield and excitation-dependent nature. Under the low pH conditions (pH 3), B/N-CQDs exhibited a robust green fluorescence emission with a significant red-shift (48 nm) and the loss of the excitation-dependent nature. The change in PL nature originated from the protonation of surface groups, a decrease in negative surface charge (from −20.6 to −1.23 eV), and finally, aggregation of the nanostructure (the size of CQDs from 4.8 to 7.5 nm). However, in the case of alkaline conditions, the deprotonation surface groups significantly enhanced the surface charge and led to the emergence of a negative ‘protective shell’ with a zeta potential of −71.3 eV. In a high pH medium (pH 13), PL spectra showed the loss of excitation-dependent features and a red-shift (35 nm) in emission peak maxima with lower intensity. This report provides significant progress in the clarification of the pH-sensitive PL mechanism of CQDs. We envision that the proposed CQDs would provide unique opportunities in the fabrication of novel pH sensor systems and fluorescence imaging where a wide range of pH sensitivity is required. Full article

(This article belongs to the Section Bioactive Coatings and Biointerfaces)

► Show Figures

Graphical abstract

11 pages, 8808 KiB

Open AccessArticle

First Principles Study of Atomic Oxygen Adsorption on Austenitic Stainless Steels Surfaces: A Theoretical Study

by Xinghua Zhu, Zhou Liu, Qingguo Feng, Zhiyong Huang, Xiaoyang Zhu, Lei Xiao, Jianguo He, Ning Wang and Yi Xu

Coatings 2023, 13(2), 455; https://doi.org/10.3390/coatings13020455 - 17 Feb 2023

Viewed by 2007

Abstract

The adsorption of atomic oxygen and surfaces is the starting point and key point to understand the oxidation process of stainless steel. Nowadays, numerous studies have focused on the metal composition of stainless steel, while the mechanism of non-metallic elements affecting atomic oxygen [...] Read more.

The adsorption of atomic oxygen and surfaces is the starting point and key point to understand the oxidation process of stainless steel. Nowadays, numerous studies have focused on the metal composition of stainless steel, while the mechanism of non-metallic elements affecting atomic oxygen adsorption needs to be clarified. Here, adsorption of atomic oxygen on the surface of pure γ-Fe and H/N-containing austenitic stainless steels was investigated using first principles. We found that stable adsorption (>6 eV) can occur on pure γ-Fe and H/N-containing austenitic surfaces. In this process, the presence of hydrogen and nitrogen both enhance the adsorption of atomic oxygen, but their influence mechanisms are in opposition. Hydrogen enhances adsorption by breaking metal bonds near the surface, while nitrogen promotes adsorption by enhancing structural stability. The adsorption promotion of hydrogen (−6.7629 eV) is stronger than that of nitrogen (−6.6374 eV), but it can reduce the stability of the system. The introduction of appropriate nitrogen atoms may be beneficial to the improvement of corrosion resistance. This study provides valid data and a unique perspective on the erosion protection of atomic oxygen on austenitic surfaces. Full article

(This article belongs to the Special Issue Recent Advances in Functional Surfaces and Interfaces)

► Show Figures

Figure 1

15 pages, 7853 KiB

Open AccessFeature PaperArticle

Distinctive Effects of Surface Roughness and Ions Release on the Bacterial Adhesion and Inactivation of Textured Copper Oxide Surfaces

by Akram Alhussein, Lylia Aouchiche, Abdelhamid Hmima, Delphine Retraint and Sami Rtimi

Coatings 2023, 13(2), 454; https://doi.org/10.3390/coatings13020454 - 16 Feb 2023

Cited by 4 | Viewed by 2061

Abstract

In this manuscript, we studied the effect of additive manufacturing pretreatment on bacterial adhesion and inactivation on copper-based interfaces. Sandblasting, mirror polishing and Surface Mechanical Attrition Treatment (SMAT) at high or low energies have been employed to modify the substrate’s (316L stainless steel) [...] Read more.

In this manuscript, we studied the effect of additive manufacturing pretreatment on bacterial adhesion and inactivation on copper-based interfaces. Sandblasting, mirror polishing and Surface Mechanical Attrition Treatment (SMAT) at high or low energies have been employed to modify the substrate’s (316L stainless steel) roughness. The pretreated substrates were coated with thin copper films using magnetron sputtering. The thin copper films’ composition and antibacterial activities were first optimized by being deposited on an Si wafer. We showed that the surface roughness profile influenced bacterial adhesion in the dark. Bacterial inactivation was monitored under indoor light. Stereomicroscopy imaging showed live/dead bacterial cells on the coated substrates. Scanning electron microscopy (SEM) showed homogeneous coating growths of copper with a columnar texture. The chemical composition of the deposited Cu thin films was carried out by Energy Dispersive X-ray Spectroscopy (EDX) and showed a uniform distribution of copper and oxygen, revealing the formation of copper oxides (Cu_xO). The oxygen content of the sputtered films varied from 7.8 to 25%, justifying the semi-conductor behavior of the thin films under indoor light. The crystallographic structure of the sputtered thin films was investigated using X-ray diffraction (XRD), showing the cubic Cu peaks and characteristic peaks of Cu₂O. The Cu peaks at 2θ values of 43.28°, 50.40° and 74.81° were attributed to the (111), (200) and (220) planes, respectively. The use of genetically modified bacteria (without porins) allowed the rationalization of the predominant effect of the extracellular bacterial inactivation compared to that of intracellular bacterial inactivation through ion release and diffusion. Full article

(This article belongs to the Special Issue Bio-Based Packaging Films: Development, Characterization, and Application)

► Show Figures

Figure 1

11 pages, 3930 KiB

Open AccessArticle

Effect of Laser Pulse Width and Intensity Distribution on the Crystallographic Characteristics of GeSn Film

by Xiaomeng Wang, Dongfeng Qi, Wenju Zhou, Haotian Deng, Yuhan Liu, Shiyong Shangguan, Jianguo Zhang, Hongyu Zheng and Xueyun Liu

Coatings 2023, 13(2), 453; https://doi.org/10.3390/coatings13020453 - 16 Feb 2023

Cited by 3 | Viewed by 1752

Abstract

Germanium-tin (GeSn) alloy is considered a promising candidate for a Si-based short-wavelength infrared range (SWIR) detector and laser source due to its excellent carrier mobility and bandgap tunability. Pulsed laser annealing (PLA) is one of the preeminent methods for preparing GeSn crystal films [...] Read more.

Germanium-tin (GeSn) alloy is considered a promising candidate for a Si-based short-wavelength infrared range (SWIR) detector and laser source due to its excellent carrier mobility and bandgap tunability. Pulsed laser annealing (PLA) is one of the preeminent methods for preparing GeSn crystal films with high Sn content. However, current reports have not systematically investigated the effect of different pulse-width lasers on the crystalline quality of GeSn films. In addition, the intensity of the spot follows the gaussian distribution. As a result, various regions would have different crystalline properties. Therefore, in this study, we first provide the Raman spectra of several feature regions in the ablation state for single spot processing with various pulse-width lasers (continuous-wave, nanosecond, femtosecond). Furthermore, the impact of laser pulse width on the crystallization characteristics of GeSn film is explored for different single-spot processing states, particularly the Sn content incorporated into GeSn crystals. The transient heating time of the film surface and the faster non-equilibrium transition of the surface temperature inhibit the segregation of the Sn component. By comparing the Raman spectra of the pulsed laser, the continuous-wave laser shows the most acute Sn segregation phenomenon, with the lowest Sn content of approximately 2%. However, the femtosecond laser both ensures crystallization of the film and effective suppression of Sn expulsion from the lattices, and the content of Sn is 8.07%, which is similar to the origin of GeSn film. Full article

(This article belongs to the Special Issue Advanced Coating Materials for Energy Storage and Conversion)

► Show Figures

Figure 1

17 pages, 12645 KiB

Open AccessArticle

Experimental Investigation on Physical Properties of Concrete Containing Polypropylene Fiber and Water-Borne Epoxy for Pavement

by Li Wang, Hongliang Zhang, Bendong Zhao, Biao Wang, Quanman Zhao and Min Sun

Coatings 2023, 13(2), 452; https://doi.org/10.3390/coatings13020452 - 16 Feb 2023

Cited by 6 | Viewed by 1987

Abstract

Cement concrete pavement accounts for a large proportion of the road network due to its excellent mechanical strength and durability. However, numerous microcracks are generated due to the high brittleness of concrete, which poses a threat to the service life of concrete pavement. [...] Read more.

Cement concrete pavement accounts for a large proportion of the road network due to its excellent mechanical strength and durability. However, numerous microcracks are generated due to the high brittleness of concrete, which poses a threat to the service life of concrete pavement. Currently, simultaneous addition of fibers and polymers is a feasible approach to resolving the issues associated with the brittleness of concrete. This study explores the properties of concrete mixtures containing different levels of polypropylene fibers and water-borne epoxy. Additionally, fly ash is also introduced to concrete mixtures. The tests performed include slump, compressive strength, flexural strength, shrinkage, depth of water penetration, and abrasion. The results indicate that water-borne epoxy, at all levels, contributed to improving the weak interfacial bonding between polypropylene fibers and concrete. In addition, the combined incorporation of polypropylene fibers and water-borne epoxy could improve the mechanical and durability properties of concrete, with the combined utilization of 0.1% polypropylene fibers and 10% water-borne epoxy exhibiting the best performance. Moreover, with the incorporation of 10% fly ash into concrete, the mechanical strength and abrasion resistance experienced a slight reduction, while the workability, drying shrinkage resistance, and impermeability were improved. The current findings indicate that the combined utilization of polypropylene fibers and water-borne epoxy at appropriate levels is beneficial for application in pavement; however, in spite of superior drying shrinkage resistance and impermeability, the incorporation of fly ash into concrete pavement should be properly treated according to the actual engineering conditions. Full article

(This article belongs to the Special Issue Functional Coatings and Surface Modifications in Cement-Matrix Composites)

► Show Figures

Figure 1

3 pages, 176 KiB

Open AccessEditorial

Special Issue: Tribological Coatings—Properties, Mechanisms, and Applications in Surface Engineering

by Suzana Jakovljević and Darko Landek

Coatings 2023, 13(2), 451; https://doi.org/10.3390/coatings13020451 - 16 Feb 2023

Cited by 1 | Viewed by 1391

Abstract

Tribological coatings are found on machine elements (e [...] Full article

(This article belongs to the Special Issue Tribological Coatings: Properties, Mechanisms, and Applications in Surface Engineering)

15 pages, 4832 KiB

Open AccessArticle

Spectral Characterization and Identification of Natural and Regenerated Leather Based on Hyperspectral Imaging System

by Qijin Hou, Xiaoke Jin, Yingjie Qiu, Zeya Zhou, Huifang Zhang, Jingjing Jiang, Wei Tian and Chengyan Zhu

Coatings 2023, 13(2), 450; https://doi.org/10.3390/coatings13020450 - 16 Feb 2023

Cited by 2 | Viewed by 2247

Abstract

Currently, the methods to identify leather materials have limitations, and identifying natural leather types is also relatively complex. In this research, the microstructures of four types of mammalian leathers (cattle leather, pig leather, sheep leather, and deer leather), three kinds of reptilian leathers [...] Read more.

Currently, the methods to identify leather materials have limitations, and identifying natural leather types is also relatively complex. In this research, the microstructures of four types of mammalian leathers (cattle leather, pig leather, sheep leather, and deer leather), three kinds of reptilian leathers (crocodile leather, lizard leather, and snake leather) and regenerated leather were characterized by scanning electron microscopy. The spectral curves (from 900 to 1700 nm) of these leather samples were extracted using a hyperspectral imaging system, and their spectral characteristics were analyzed. A method of leather identification by the hyperspectral imaging system combined with chemometrics was established. The results showed that the spectral curves of natural and regenerated leather differed in the number, position, and depth of the characteristic peaks, enabling the classification of regenerated leather by comparative analysis with the naked eye. The first-order derivative processing–principal component analysis–discriminant analysis model achieved a 98% correct classification rate, confirming the hyperspectral imaging system’s feasibility in the leather material identification field. We believe that his research is beneficial for the leather industry to understand the classifications scientifically, in order to protect consumer rights and further develop the leather testing industry. Full article

(This article belongs to the Special Issue Sustainable Coatings for Functional Textile and Packaging Materials)

► Show Figures

Figure 1

17 pages, 22639 KiB

Open AccessFeature PaperArticle

Step-by-Step Modeling and Experimental Study on the Sol–Gel Porous Structure of Percolation Nanoclusters

by Irina Kononova, Pavel Kononov and Vyacheslav Moshnikov

Coatings 2023, 13(2), 449; https://doi.org/10.3390/coatings13020449 - 16 Feb 2023

Cited by 2 | Viewed by 1933

Abstract

Non-conventional crystallization techniques have been developed in recent years. Non-conventional crystallization techniques use primary structural elements (for example, clusters) rather than atoms and molecules. Modern nanomaterial science is going through great changes as an entirely new approach of non-conventional growth mechanisms is emerging [...] Read more.

Non-conventional crystallization techniques have been developed in recent years. Non-conventional crystallization techniques use primary structural elements (for example, clusters) rather than atoms and molecules. Modern nanomaterial science is going through great changes as an entirely new approach of non-conventional growth mechanisms is emerging due to cluster coupling, catalyzing interest in cluster physics. The formation of fractal and percolation clusters has increased. We carried out step-by-step modeling and an experimental study of the formation of fractal and percolation clusters based on tin dioxide and silicon dioxide and formed by sol–gel technology. In this paper, the growth of fractal aggregates (clusters) from sol particles SnO₂ and SiO₂ based on the modified models of diffusion-limited and cluster–cluster aggregation is discussed. A percolation model using simulated fractal clusters of SnO₂ and SiO₂ particles is proposed. Experimental data on the sol–gel percolation structure of porous nanocomposites are presented. The modeling of SnO₂ and SiO₂ particles, which also consist of clusters (the next step in the hierarchy), is shown. We propose a generalized hierarchical three-dimensional percolation cluster model that allows calculating the surface area, knowing the experimental sizes of macropores and taking into account the micro- and mesopores (sizes less than a few nanometers). Full article

(This article belongs to the Special Issue Investigation on Sol–Gel Based Coatings Application)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Coatings, Volume 13, Issue 2 (February 2023) – 263 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI