Coatings

14 pages, 3313 KiB

Open AccessArticle

Investigation of Droplet Atomization and Evaporation in Solution Precursor Plasma Spray Coating

by Hongbing Xiong^* and Weiqi Sun

Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province, Zhejiang University, Hangzhou 310027, China

Coatings 2017, 7(11), 207; https://doi.org/10.3390/coatings7110207 - 21 Nov 2017

Cited by 15 | Viewed by 6410

Solution precursor plasma spray (SPPS) is a novel and promising technique in producing nanostructured coatings. This technique involves complex heat, mass and momentum transfer among the liquid feedstock, droplets, plasma jet and the coating material. Nevertheless, the droplet atomization and evaporation in the [...] Read more.

Solution precursor plasma spray (SPPS) is a novel and promising technique in producing nanostructured coatings. This technique involves complex heat, mass and momentum transfer among the liquid feedstock, droplets, plasma jet and the coating material. Nevertheless, the droplet atomization and evaporation in the plasma jet is one of the most essential parts to obtain the desired coating architecture. In the present work, a three-dimensional two-way-coupled Eulerian-Lagrangian code is used to simulate the interactions between the solution precursor and plasma. In order to obtain a more realistic understanding regarding droplet atomization and vaporization, the flash-boiling effect is modeled by an improved vaporization model. This model could provide accurate details for the droplet pyrolysis and help to optimize the solution precursor plasma spray process. We show that the fragmentation of the liquid stock and its vaporization mainly dominate the spraying details and can be decisive to the coating quality. We further investigate their role in SPPS and separately probe their inner link with the flow field relating to the distinctive area when droplets are flying through the thermal flow field. Our studies reveal that ethanol droplets, compared to those of water, show a superior characteristics in SPPS, owing to the low boiling point and low surface tension, conducive to the evaporation and atomization of droplets. In addition, the mixture of the plasma gas with hydrogen breaks the droplets more thoroughly compared to the pure plasma. The numerical results were compared and found to agree well with previous experimental and simulation work. Full article

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12 pages, 3924 KiB

Open AccessArticle

Suppression of Graphene Nucleation by Turning Off Hydrogen Supply Just before Atmospheric Pressure Chemical Vapor Deposition Growth

by Seiya Suzuki^*, Yoshifumi Terada and Masamichi Yoshimura

Graduate School of Engineering, Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Aichi, Nagoya 468-8511, Japan

Coatings 2017, 7(11), 206; https://doi.org/10.3390/coatings7110206 - 20 Nov 2017

Cited by 13 | Viewed by 8892

Abstract

To exploit the extraordinary property of graphene in practical electrical and optical devices, it is necessary to produce large-sized, single-crystal graphene. Atmospheric pressure chemical vapor deposition (APCVD) on polycrystalline Cu surface is a promising scalable route of graphene synthesis but the unavoidable multiple [...] Read more.

To exploit the extraordinary property of graphene in practical electrical and optical devices, it is necessary to produce large-sized, single-crystal graphene. Atmospheric pressure chemical vapor deposition (APCVD) on polycrystalline Cu surface is a promising scalable route of graphene synthesis but the unavoidable multiple nucleation limits their reachable domain size. Here, we report that effective suppression of nucleation was achieved by only turning off hydrogen supply before introduction of the carbon source for graphene growth. The density of graphene decreased from 72.0 to 2.2 domains/cm² by turning off hydrogen for 15 min. X-ray photoelectron spectroscopy and Raman spectroscopy studies show that the Cu surface was covered with 3–4 nm thick highly crystalline Cu₂O, which would be caused by oxidation by residual oxidative gasses in the chamber during the turning off period. It was also revealed that elevating the temperature in Ar followed by annealing in H₂/Ar before turning off hydrogen led to the enlargement of the Cu domain, resulting in the further suppression of nucleation. By optimizing such growth parameters in the CVD process, a single-crystal graphene with ~2.6 mm in diameter was successfully obtained. Full article

(This article belongs to the Special Issue Chemical Vapor Deposition)

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18 pages, 12761 KiB

Open AccessArticle

Wear Transition of CrN Coated M50 Steel under High Temperature and Heavy Load

by Chi Zhang¹

, Le Gu^1,*, Guangze Tang² and Yuze Mao¹

¹ Research Lab of Space & Aerospace Tribology, Harbin Institute of Technology, Harbin 150001, China

² School of Material Science and Technology, Harbin Institute of Technology, Harbin 150001, China

Coatings 2017, 7(11), 202; https://doi.org/10.3390/coatings7110202 - 20 Nov 2017

Cited by 18 | Viewed by 5871

Abstract

The combination of high temperature indentation and wear test provides a useful way to investigate wear of CrN coating and wear transition mechanisms. In this paper, the high temperature hardness of CrN coatings and load bearing capacity, L_b, of CrN coated [...] Read more.

The combination of high temperature indentation and wear test provides a useful way to investigate wear of CrN coating and wear transition mechanisms. In this paper, the high temperature hardness of CrN coatings and load bearing capacity, L_b, of CrN coated M50 disks were determined from spherical indentation at temperatures up to 500 °C. Wear tests with different normal loads were carried out at the same temperatures as the indentation tests. The results show that wear mechanism of CrN coating changes with external load, P, and temperature, T. Under a tested condition of P < L_b and T < 315 °C, abrasive is the dominant wear mechanism for CrN coating. Under a tested condition of P < L_b and T ≥ 315 °C, wear of CrN coating transitions into mild oxidation wear due to the lubricating effect of chromium oxide film. Under a tested condition of P > L_b and T < 315 °C, wear of CrN coating was controlled by coating fracture. Under a tested condition of P > L_b and T ≥ 315 °C, wear of CrN coating transitions into the severe wear mode, due to the tensile fracture of oxidation films, thereby leading to adhesion between CrN coating and tribo-counterpart. The presented method can be helpful in predicting permissible load and working temperature in tribological applications of CrN coating. Full article

(This article belongs to the Special Issue Coatings for Harsh Environments)

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9 pages, 5052 KiB

Open AccessArticle

Improvement of Power Factor of CoSb₃ Thermoelectric Thin Films via Microstructure Optimization

by Zhuanghao Zheng^1,2, Meng Wei¹, Fu Li¹, Jingting Luo¹, Guangxing Liang¹, Hongli Ma², Xianghua Zhang^2,* and Ping Fan^1,*

¹ Institute of Thin Film Physics and Applications, Shenzhen Key Laboratory of Advanced Thin Films and Applications, College of Physics and Energy, Shenzhen University, Shenzhen 518060, China

² Laboratory of Glasses and Ceramics, Institute of Chemical Science UMR CNRS 6226, University of Rennes 1, 35042 Rennes, France

Coatings 2017, 7(11), 205; https://doi.org/10.3390/coatings7110205 - 18 Nov 2017

Cited by 9 | Viewed by 4683

Abstract

Skutterudite CoSb₃ has emerged as one of the most studied candidate materials for thermoelectric applications. In this work, CoSb₃ thin films were prepared by radio frequency sputtering, and their microstructure was investigated with emphasis on the effect of target composition and [...] Read more.

Skutterudite CoSb₃ has emerged as one of the most studied candidate materials for thermoelectric applications. In this work, CoSb₃ thin films were prepared by radio frequency sputtering, and their microstructure was investigated with emphasis on the effect of target composition and deposition temperature. The goal was to enhance the thermoelectric properties of CoSb₃ thin films via microstructure optimization. Results showed that the Sb content of films gradually decreased with increasing deposition temperature. Although the thin films prepared by the target with a Co and Sb element ratio of 1:3.5 approached the ideal stoichiometric ratio, they showed poor thermoelectric properties due to the formation of an additional Sb phase. By contrast, the thin films obtained with insufficient Sb showed a single CoSb₃ phase and good thermoelectric properties. The mechanism behind this difference was studied accordingly. The power factor of the thin films was enhanced due to their dense structure and good crystallization. Full article

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7 pages, 218 KiB

Open AccessArticle

Inactivation of Listeria in Foods Packed in Films Activated with Enterocin AS-48 plus Thymol Singly or in Combination with High-Hydrostatic Pressure Treatment

by Irene Ortega Blázquez, María José Grande Burgos, Rubén Pérez-Pulido, Antonio Gálvez^* and Rosario Lucas

Department of Health Sciences, University of Jaen, 23071 Jaén, Spain

Coatings 2017, 7(11), 204; https://doi.org/10.3390/coatings7110204 - 18 Nov 2017

Cited by 8 | Viewed by 3780

Abstract

The aim of the present study was to determine the efficacy of films activated with enterocin AS-48 plus thymol singly, or in combination with high-hydrostatic pressure (HHP) on the inactivation of Listeria innocua in sea bream fillets and in fruit puree stored under [...] Read more.

The aim of the present study was to determine the efficacy of films activated with enterocin AS-48 plus thymol singly, or in combination with high-hydrostatic pressure (HHP) on the inactivation of Listeria innocua in sea bream fillets and in fruit puree stored under refrigeration for 10 days. L. innocua proliferated in control fish fillets during storage. The activated film reduced viable Listeria counts in fillets by 1.76 log cycles and prevented growth of survivors until mid-storage. Application of HHP treatment to fillets packed in films without antimicrobials reduced Listeria counts by 1.83 log cycles, but did not prevent the growth of survivors during storage. The combined treatment reduced viable counts by 1.88 log cycles and delayed growth of survivors during the whole storage period. L. innocua survived in puree during storage. The activated film reduced Listeria counts by 1.80 and 2.0 log cycles at days 0 and 3. After that point, Listeria were below the detection limit. No viable Listeria were detected in the purees after application of HHP treatment singly, or in combination with the activated film. Results from the study indicate that the efficacy of activated films against Listeria is markedly influenced by the food type. Full article

12 pages, 7738 KiB

Open AccessArticle

Corrosion and Thermal Fatigue Behaviors of TiC/Ni Composite Coating by Self-Propagating High-Temperature Synthesis in Molten Aluminum Alloy

by Chenggang Pan^1,*, Dudu Liu¹, Chuanxiang Zhao¹, Qingming Chang¹ and Peng He²

¹ The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, China

² Wuhan Second Ship Design and Research Institute, Wuhan 430205, China

Coatings 2017, 7(11), 203; https://doi.org/10.3390/coatings7110203 - 18 Nov 2017

Cited by 9 | Viewed by 4906

Abstract

TiC/Ni composite coatings on H13 steel plates were fabricated in situ by self-propagating high-temperature synthesis and combined with a pseudo-heat isostatic press. The microstructure of the coating was characterized by X-ray diffraction and scanning electron microscopy. The microhardness, corrosion, and thermal fatigue behaviors [...] Read more.

TiC/Ni composite coatings on H13 steel plates were fabricated in situ by self-propagating high-temperature synthesis and combined with a pseudo-heat isostatic press. The microstructure of the coating was characterized by X-ray diffraction and scanning electron microscopy. The microhardness, corrosion, and thermal fatigue behaviors of the coating were investigated by a microhardness test, immersion test, and thermal fatigue test, respectively. The results showed that the in situ coating consisted of TiC and Ni binder phases. Spheroidal TiC particles were enveloped by a nearly continuous Ni binder phase. Coating showed good metallurgical bonding in the interface. The corrosive mechanism of the coating surface in molten aluminum alloy involves the Ni binder phase being etched by aluminum to form AlNi₃ and the oxidization of the TiC-reinforced phase. The corrosive mechanism that occurred at the front of the corrosion involves the Ni binder phase of the coating being etched by aluminum to form AlNi₃, while the TiC skeleton still maintains the original organizational structure. Hot fatigue cracks began at the defective tips of the coating and propagated in the TiC-reinforced phase. The crack is a trans-granular fracture, which is the result of brittle rupture. Full article

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12 pages, 24228 KiB

Open AccessArticle

Mechanical and Spectroscopic Analysis of Retrieved/Failed Dental Implants

by Umer Daood^1,*, Ninette Banday², Zohaib Akram³, James K. H. Tsoi⁴

, Prasanaa Neelakantan⁴, Hanan Omar¹, Tariq Abduljabbar⁵, Fahim Vohra⁵, Nawwaf Al-Hamoudi⁶ and Amr S. Fawzy^7,8

¹ Faculty of Dentistry, International Medical University, Wilayah Persekutuan Kuala Lumpur 57000, Malaysia

² UAE Health Authority, Abu Dhabi 45728, United Arab Emirates

³ Department of Periodontology, Faculty of Dentistry, Ziauddin University, Karachi 75600, Pakistan

⁴ Faculty of Dentistry, The University of Hong Kong, Hong Kong

⁵ Department of Prosthetic Dental Science, Faculty of Dentistry, King Saud University, Riyadh 60169, Saudi Arabia

⁶ Department of Periodontics and Community Dentistry, King Saud University, Riyadh 60169, Saudi Arabia

⁷ Faculty of Dentistry, National University of Singapore, Singapore 119083, Singapore

⁸ Oral Restorative and Rehabilitative Sciences, The University of Western Australia, Crawley, WA 6009, Australia

Coatings 2017, 7(11), 201; https://doi.org/10.3390/coatings7110201 - 15 Nov 2017

Cited by 5 | Viewed by 6721

Abstract

The purpose of this study was to examine surface alterations and bone formation on the surface of failed dental implants (Straumann [ST] and TiUnite [TiUn]) removed due to any biological reason. In addition, failure analysis was performed to test mechanical properties. Dental implants [...] Read more.

The purpose of this study was to examine surface alterations and bone formation on the surface of failed dental implants (Straumann [ST] and TiUnite [TiUn]) removed due to any biological reason. In addition, failure analysis was performed to test mechanical properties. Dental implants (n = 38) from two manufacturers were collected and subjected to chemical cleaning. The presence of newly formed hydroxyapatite bone around failed implants was evaluated using micro-Raman spectroscopy. Scanning electron microscopy was used to identify surface defects. Mechanical testing was performed using a Minneapolis servo-hydraulic system (MTS) along with indentation using a universal testing machine and average values were recorded. A statistical analysis of mechanical properties was done using an unpaired t test, and correlation between observed defects was evaluated using Chi-square (p = 0.05). Apatite-formation was evident in both implants, but was found qualitatively more in the ST group. No significant difference was found in indentation between the two groups (p > 0.05). The percentage of “no defects” was significantly lower in the ST group (71%). Crack-like and full-crack defects were observed in 49% and 39% of TiUn. The ST group showed 11,061 cycles to failure as compared with 10,021 cycles in the TiUnite group. Implant failure mechanisms are complex with a combination of mechanical and biological reasons and these factors are variable with different implant systems. Full article

(This article belongs to the Special Issue Dental Implant Surface: Science and Technology)

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9 pages, 17108 KiB

Open AccessArticle

Effect of Initial Surface Roughness on Cavitation Erosion Resistance of Arc-Sprayed Fe-Based Amorphous/Nanocrystalline Coatings

by Jinran Lin^1,2,3,*

, Zehua Wang², Jiangbo Cheng², Min Kang¹, Xiuqing Fu¹ and Sheng Hong^2,4

¹ College of Engineering, Nanjing Agricultural University, Nanjing 210031, China

² College of Mechanics and Materials, Hohai University, Nanjing 211100, China

³ Jiangsu Jinxiang Transmission Equipment Co., Ltd., Huaian 223001, China

⁴ Material Corrosion and Protection Key Laboratory of Sichuan Province, Zigong 643000, China

Coatings 2017, 7(11), 200; https://doi.org/10.3390/coatings7110200 - 14 Nov 2017

Cited by 37 | Viewed by 5658

Abstract

The arc spraying process was used to prepare Fe-based amorphous/nanocrystalline coating. The cavitation erosion behaviors of FeNiCrBSiNbW coatings with different surface roughness levels were investigated in distilled water. The results showed that FeNiCrBSiNbW coating adhered well to the substrate, and was compact with [...] Read more.

The arc spraying process was used to prepare Fe-based amorphous/nanocrystalline coating. The cavitation erosion behaviors of FeNiCrBSiNbW coatings with different surface roughness levels were investigated in distilled water. The results showed that FeNiCrBSiNbW coating adhered well to the substrate, and was compact with porosity of less than 2%. With increasing initial surface roughness, the coatings showed an increase in mass loss of cavitation erosion damage. The amount of pre-existing defects on the initial surface of the coatings was found to be a significant factor for the difference in the cavitation erosion behavior. The cavitation erosion damage for the coatings was a brittle erosion mode. The evolution of the cavitation erosion mechanism of the coatings with the increase of the initial surface roughness was micro-cracks, pits, detachment of fragments, craters, cracks, pullout of the un-melted particle, and massive exfoliations. Full article

(This article belongs to the Special Issue Coatings for Harsh Environments)

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13 pages, 6923 KiB

Open AccessArticle

Electrophoretic Deposition as a New Bioactive Glass Coating Process for Orthodontic Stainless Steel

by Kyotaro Kawaguchi¹, Masahiro Iijima^1,*, Kazuhiko Endo² and Itaru Mizoguchi¹

¹ Division of Orthodontics and Dentofacial Orthopedics, School of Dentistry, Health Sciences University of Hokkaido, Hokkaido 061-0293, Japan

² Division of Biomaterials and Bioengineering, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293, Japan

Coatings 2017, 7(11), 199; https://doi.org/10.3390/coatings7110199 - 13 Nov 2017

Cited by 18 | Viewed by 7287

Abstract

This study investigated the surface modification of orthodontic stainless steel using electrophoretic deposition (EPD) of bioactive glass (BG). The BG coatings were characterized by spectrophotometry, scanning electron microscopy with energy dispersive X-ray spectrometry, and X-ray diffraction. The frictional properties were investigated using a [...] Read more.

This study investigated the surface modification of orthodontic stainless steel using electrophoretic deposition (EPD) of bioactive glass (BG). The BG coatings were characterized by spectrophotometry, scanning electron microscopy with energy dispersive X-ray spectrometry, and X-ray diffraction. The frictional properties were investigated using a progressive load scratch test. The remineralization ability of the etched dental enamel was studied according to the time-dependent mechanical properties of the enamel using a nano-indentation test. The EPD process using alternating current produced higher values in both reflectance and lightness. Additionally, the BG coating was thinner than that prepared using direct current, and was completely amorphous. All of the BG coatings displayed good interfacial adhesion, and Si and O were the major components. Most BG-coated specimens produced slightly higher frictional forces compared with non-coated specimens. The hardness and elastic modulus of etched enamel specimens immersed with most BG-coated specimens recovered significantly with increasing immersion time compared with the non-coated specimen, and significant acid-neutralization was observed for the BG-coated specimens. The surface modification technique using EPD and BG coating on orthodontic stainless steel may assist the development of new non-cytotoxic orthodontic metallic appliances having satisfactory appearance and remineralization ability. Full article

(This article belongs to the Special Issue Surface Engineering of Biomaterials)

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9 pages, 2787 KiB

Open AccessArticle

Effect of Microstructure on the Thermal Conductivity of Plasma Sprayed Y₂O₃ Stabilized Zirconia (8% YSZ)

by Ningning Hu^1,2, Matiullah Khan^2,3

, Yongzhe Wang², Xuemei Song², Chucheng Lin², Chengkang Chang¹ and Yi Zeng^2,*

¹ School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418, China

² The State Key Lab of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China

³ Department of Physics, Kohat University of Science and Technology, Kohat 26000, Pakistan

Coatings 2017, 7(11), 198; https://doi.org/10.3390/coatings7110198 - 13 Nov 2017

Cited by 28 | Viewed by 5842

Abstract

In this paper, the effect of microstructure on the thermal conductivity of plasma-sprayed Y₂O₃ stabilized ZrO₂ (YSZ) thermal barrier coatings (TBCs) is investigated. Nine freestanding samples deposited on aluminum alloys are studied. Cross-section morphology such as pores, cracks, m-phase [...] Read more.

In this paper, the effect of microstructure on the thermal conductivity of plasma-sprayed Y₂O₃ stabilized ZrO₂ (YSZ) thermal barrier coatings (TBCs) is investigated. Nine freestanding samples deposited on aluminum alloys are studied. Cross-section morphology such as pores, cracks, m-phase content, grain boundary density of the coated samples are examined by scanning electron microscopy (SEM) and electron back-scattered diffraction (EBSD). Multiple linear regressions are used to develop quantitative models that describe the relationship between the particle parameters, m-phase content and features of the microstructure such as porosity, crack-porosity, and the length density of small and big angle-cracks. Moreover, the relationship between the microstructure and thermal conductivity is investigated. Results reveal that the thermal conductivity of the coating is mainly determined by the microstructure and grain boundary density at room temperature (25 °C), and by the length density of big-angle-crack, monoclinic phase content and grain boundary density at high temperature (1200 °C). Full article

(This article belongs to the Special Issue Applications of Spray Coating in Fabrication of Thin Film Devices and Coatings)

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13 pages, 5262 KiB

Open AccessArticle

Characterization of Hydroxyapatite (HA) Sputtering Targets by APS Methods

by Kuo-Yung Hung^1,*, Hong-Chen Lai², Yung-Chin Yang³ and Hui-Ping Feng¹

¹ Department of Mechanical Engineering, Ming Chi University of Technology, New Taipei City 24301, Taiwan

² Institute of Mechanical and Electrical Engineering, Ming Chi University of Technology, New Taipei City 24301, Taiwan

³ Institute of Materials Science and Engineering, National Taipei University of Technology, Taipei 10608, Taiwan

Coatings 2017, 7(11), 197; https://doi.org/10.3390/coatings7110197 - 11 Nov 2017

Cited by 7 | Viewed by 6143

Abstract

Radio frequency (RF) sputtering is a potential medical device coating technology that is commercializable; however, a suitable commercialized target for sputtering the hydroxyapatite (HA) coating onto titanium medical devices is more important. Therefore, this study used three HA targets in conducting sputtering experiments [...] Read more.

Radio frequency (RF) sputtering is a potential medical device coating technology that is commercializable; however, a suitable commercialized target for sputtering the hydroxyapatite (HA) coating onto titanium medical devices is more important. Therefore, this study used three HA targets in conducting sputtering experiments for HA films, which were manufactured in a laboratory by using three different processes: cold pressing and sintering (CPS), hot isostatic pressing (HIP), and atmospheric plasma spraying (APS). Subsequently, the sputtering performance of each type of target and the properties of the HA films were assessed to develop an appropriate process for modifying the surfaces of medical devices. The experimental results showed that the APS target, with a density of approximately 2.83 g/cm³, was suitable for use in HA sputtering. Additionally, the APS target could withstand a high discharge power over 300 W, whereas the CPS target could nearly endure a power below 70 W. The APS target, with Ca/P ratio of 2.401, consisted of a combination of HA, α-tricalcium phosphate (α-TCP), β-TCP, and tetracalcium phosphate phases (TTCP). In addition to being able to perform at a high sputtering power of more than 300 W, the APS target achieved a higher deposition rate than did the CPS target. This study shows that the processing technology used for the APS target is a potential method for applying HA sputtering for the surface modification of artificial aggregates. Full article

(This article belongs to the Special Issue Dental Implant Surface: Science and Technology)

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15 pages, 4066 KiB

Open AccessArticle

Effective Postharvest Preservation of Kiwifruit and Romaine Lettuce with a Chitosan Hydrochloride Coating

by Elena Fortunati^1,*

, Geremia Giovanale², Francesca Luzi¹, Angelo Mazzaglia², Josè Maria Kenny¹

, Luigi Torre¹ and Giorgio Mariano Balestra^2,*

¹ Department of Civil and Environmental Engineering, University of Perugia, UdR INSTM, Strada di Pentima 4, 05100 Terni, Italy

² Department of Agriculture and Forestry Science (DAFNE), University of Tuscia, Via S. Camillo De Lellis snc, 01100 Viterbo, Italy

Coatings 2017, 7(11), 196; https://doi.org/10.3390/coatings7110196 - 11 Nov 2017

Cited by 33 | Viewed by 8943

Abstract

Kiwifruits and romaine lettuce, among the most horticulturally-consumed fresh products, were selected to investigate how to reduce damage and losses before commercialization. The film-forming properties, physico-chemical, and morphological characteristics, as well as the antimicrobial response against Botrytis cinerea and Pectobacterium carotovorum subsp. carotovorum [...] Read more.

Kiwifruits and romaine lettuce, among the most horticulturally-consumed fresh products, were selected to investigate how to reduce damage and losses before commercialization. The film-forming properties, physico-chemical, and morphological characteristics, as well as the antimicrobial response against Botrytis cinerea and Pectobacterium carotovorum subsp. carotovorum of chitosan hydrochloride (CH)-based coatings were investigated. The results underlined the film-forming capability of this CH that maintained its physico-chemical characteristics also after dissolution in water. Morphological investigations by FESEM (Field Emission Scanning Electron Microscopy) underlined a well-distributed and homogeneous thin coating (less than 3–5 μm) on the lettuce leaves that do not negatively affect the food product functionality, guaranteeing the normal breathing of the food. FESEM images also highlighted the good distribution of CH coating on kiwifruit peels. The in vitro antimicrobial assays showed that both the mycelial growth of Botrytis cinerea and the bacterial growth of Pectobacterium carotovorum subsp. carotovorum were totally inhibited by the presence of CH, whereas in vivo antimicrobial properties were proved for 5–7 days on lettuce and until to 20–25 days on kiwifruits, demonstrating that the proposed coating is able to contrast gray mold frequently caused by the two selected plant pathogens during postharvest phases of fruit or vegetable products. Full article

(This article belongs to the Special Issue Functional Coatings for Food Packaging Applications)

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15 pages, 52070 KiB

Open AccessArticle

Nucleation and Growth of Intermetallic Compounds Formed in Boron Steel Hot-Dipped in Al–Ni alloy

by Jae-Hyeong Lee¹, Jung-Gil Yun², Sung-Yun Kwak¹ and Chung-Yun Kang^1,*

¹ Department of Material Science and Engineering, Pusan National University, Busan 46241, Korea

² Department of Hybrid Materials and Machining technology, Graduate School of Convergence Science, Pusan National University, Busan 46241, Korea

Coatings 2017, 7(11), 195; https://doi.org/10.3390/coatings7110195 - 10 Nov 2017

Cited by 8 | Viewed by 4914

Abstract

The formation mechanism of intermetallic compounds formed in boron steel hot-dipped in Al–7Ni (wt %) at 690 °С for 10–120 s was studied by identifying the intermetallic phases and investigating the growth process. Initially, a Fe₃O₄ oxide layer formed on [...] Read more.

The formation mechanism of intermetallic compounds formed in boron steel hot-dipped in Al–7Ni (wt %) at 690 °С for 10–120 s was studied by identifying the intermetallic phases and investigating the growth process. Initially, a Fe₃O₄ oxide layer formed on the steel. The oxide layer separated into multiple layers sporadically; following this, the Al–Ni molten alloy permeated into the region of the oxide layer breakdown and formed the Al₉FeNi (T, monoclinic, space group: P21/c) phase on the steel surfaces. The Al₉FeNi (T) phase formed from the reaction between the Al–Ni molten alloy and Fe eluted from the steel; this phase not only acts as an Al interdiffusion channel, but also as a barrier for Fe; and facilitates only grain growth without a significant change in thickness. Inside the steel, the Fe₂Al₅ (η, orthorhombic, space group: Cmcm) phase grows along the c-axis in the [001] direction; and has a long columnar structure. The Fe₃AlC (κ, Cubic, space group: Pm3m) phase is formed owing to a reduction in the Al concentration and the simultaneous diffusion and discharge of C toward the steel interface, as C cannot dissolve in the Fe₂Al₅ (η) phase. Full article

(This article belongs to the Special Issue Innovative Coatings for Automotive Industry)

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12 pages, 7451 KiB

Open AccessArticle

Fabrication of an Anisotropic Superhydrophobic Polymer Surface Using Compression Molding and Dip Coating

by Kyong-Min Lee¹, Chi-Vinh Ngo¹, Ji-Young Jeong², Eun-chae Jeon², Tae-Jin Je² and Doo-Man Chun^1,*

¹ School of Mechanical Engineering, University of Ulsan, Ulsan 44610, Korea

² Department of Nano Manufacturing Technology, Korea Institute of Machinery and Materials, Daejeon 34103, Korea

Coatings 2017, 7(11), 194; https://doi.org/10.3390/coatings7110194 - 10 Nov 2017

Cited by 20 | Viewed by 6589

Abstract

Many studies of anisotropic wetting surfaces with directional structures inspired from rice leaves, bamboo leaves, and butterfly wings have been carried out because of their unique liquid shape control and transportation. In this study, a precision mechanical cutting process, ultra-precision machining using a [...] Read more.

Many studies of anisotropic wetting surfaces with directional structures inspired from rice leaves, bamboo leaves, and butterfly wings have been carried out because of their unique liquid shape control and transportation. In this study, a precision mechanical cutting process, ultra-precision machining using a single crystal diamond tool, was used to fabricate a mold with microscale directional patterns of triangular cross-sectional shape for good moldability, and the patterns were duplicated on a flat thermoplastic polymer plate by compression molding for the mass production of an anisotropic wetting polymer surface. Anisotropic wetting was observed only with microscale patterns, but the sliding of water could not be achieved because of the pinning effect of the micro-structure. Therefore, an additional dip coating process with 1H, 1H, 2H, 2H-perfluorodecythricholosilanes, and TiO₂ nanoparticles was applied for a small sliding angle with nanoscale patterns and a low surface energy. The anisotropic superhydrophobic surface was fabricated and the surface morphology and anisotropic wetting behaviors were investigated. The suggested fabrication method can be used to mass produce an anisotropic superhydrophobic polymer surface, demonstrating the feasibility of liquid shape control and transportation. Full article

(This article belongs to the Special Issue Superhydrophobic Coatings)

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14 pages, 5163 KiB

Open AccessArticle

In Situ Synthesis and Electrophoretic Deposition of NiO/Ni Core-Shell Nanoparticles and Its Application as Pseudocapacitor

by Joaquin Yus¹, Begoña Ferrari¹, Antonio Javier Sanchez-Herencia¹

, Alvaro Caballero²

, Julian Morales² and Zoilo Gonzalez^1,*

¹ Instituto de Cerámica y Vidrio, Spanish National Research Council (CSIC) Madrid, 28049, Spain

² I.U.I Química Fina y Nanoquímica, Departamento Química Inorgánica e Ingeniería Química, Universidad de Córdoba, Córdoba, 14014, Spain

Coatings 2017, 7(11), 193; https://doi.org/10.3390/coatings7110193 - 8 Nov 2017

Cited by 17 | Viewed by 7205

Abstract

A simple, low cost and transferable colloidal processing method and the subsequent heat treatment has been optimized to prepare binder-free electrodes for their application in supercapacitors. NiO/Ni core–shell hybrid nanostructures have been synthetized by heterogeneous precipitation of metallic Ni nanospheres onto NiO nanoplatelets [...] Read more.

A simple, low cost and transferable colloidal processing method and the subsequent heat treatment has been optimized to prepare binder-free electrodes for their application in supercapacitors. NiO/Ni core–shell hybrid nanostructures have been synthetized by heterogeneous precipitation of metallic Ni nanospheres onto NiO nanoplatelets as seed surfaces. The electrophoretic deposition (EPD) has been used to shape the electroactive material onto 3D substrates such as Ni foams. The method has allowed us to control the growth and the homogeneity of the NiO/Ni coatings. The presence of metallic Nickel in the microstructure and the optimization of the thermal treatment have brought several improvements in the electrochemical response due to the connectivity of the final microstructure. The highest specific capacitance value has been obtained using a thermal treatment of 325 °C during 1 h in Argon. At this temperature, necks formed among ceramic-metallic nanoparticles preserve the structural integrity of the microstructure avoiding the employment of binders to enhance their connectivity. Thus, a compromise between porosity and connectivity should be established to improve electrochemical performance. Full article

(This article belongs to the Special Issue Electrophoretic Deposition)

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13 pages, 4865 KiB

Open AccessArticle

Visible-Light-Driven, Dye-Sensitized TiO₂ Photo-Catalyst for Self-Cleaning Cotton Fabrics

by Ishaq Ahmad and Chi-wai Kan^*

Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China

Coatings 2017, 7(11), 192; https://doi.org/10.3390/coatings7110192 - 6 Nov 2017

Cited by 35 | Viewed by 7680

Abstract

We report here the photo-catalytic properties of dye-sensitized TiO₂-coated cotton fabrics. In this study, visible-light-driven, self-cleaning cotton fabrics were developed by coating the cotton fabrics with dye-sensitized TiO₂. TiO₂ nano-sol was prepared via the sol-gel method and the [...] Read more.

We report here the photo-catalytic properties of dye-sensitized TiO₂-coated cotton fabrics. In this study, visible-light-driven, self-cleaning cotton fabrics were developed by coating the cotton fabrics with dye-sensitized TiO₂. TiO₂ nano-sol was prepared via the sol-gel method and the cotton fabric was coated with this nano-sol by the dip-pad–dry-cure method. In order to enhance the photo-catalytic properties of this TiO₂-coated cotton fabric under visible light irradiation, the TiO₂-coated cotton fabric was dyed with a phthalocyanine-based reactive dye, C.I. Reactive Blue 25 (RB-25), as a dye sensitizer for TiO₂. The photo-catalytic self-cleaning efficiency of the resulting dye/TiO₂-coated cotton fabrics was evaluated by degradation of Rhodamine B (RhB) and color co-ordinate measurements. Dye/TiO₂-coated cotton fabrics show very good photo-catalytic properties under visible light. Full article

(This article belongs to the Special Issue Advances in Functional Inorganic Coatings)

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12 pages, 10895 KiB

Open AccessArticle

Friction and Wear Behavior of an Ag–Mo Co-Implanted GH4169 Alloy via Ion-Beam-Assisted Bombardment

by Jiajun Zhu^*, Meng Xu, Wulin Yang, Deyi Li, Lingping Zhou and Licai Fu^*

College of Materials Science and Engineering, Hunan University, Changsha 410082, China

Coatings 2017, 7(11), 191; https://doi.org/10.3390/coatings7110191 - 6 Nov 2017

Cited by 8 | Viewed by 6172

Abstract

Ag, Mo, and Ag–Mo were respectively implanted into GH4169 alloy substrates without heating via ion-beam-assisted bombardment technology (IBAB). In addition, the wear performance under low sliding speed and applied load were researched at room temperature (RT). A small amount silver molybdate phase could [...] Read more.

Ag, Mo, and Ag–Mo were respectively implanted into GH4169 alloy substrates without heating via ion-beam-assisted bombardment technology (IBAB). In addition, the wear performance under low sliding speed and applied load were researched at room temperature (RT). A small amount silver molybdate phase could be detected on the surface of the co-implanted GH4169 alloy bombarded by a high-energy ion beam. The average friction coefficients under the steady wear state had almost no change at all. Compared with the un-implanted GH4169 alloys, the wear rate of the GH4169 alloys with co-implantation of Ag and Mo was reduced by 75%. A large amount of the silver molybdate phase could be generated due to the tribo-reaction on the worn surface during sliding. It benefits the formation of continuous oxide layers as lubrication and protected layers, leading to the change in the predominant wear mechanism from abrasion and adhesion wear to oxidation wear. Full article

(This article belongs to the Special Issue Coatings Tribology)

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7 pages, 3066 KiB

Open AccessArticle

Role of Phase Composition of PEO Coatings on AA2024 for In-Situ LDH Growth

by Maria Serdechnova^1,*, Marta Mohedano², Anissa C. Bouali¹, Daniel Höche¹, Boris Kuznetsov³, Sergey Karpushenkov³, Carsten Blawert¹ and Mikhail L. Zheludkevich^1,4

¹ Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, 21502 Geesthacht, Germany

² Departamento de Ciencia de Materiales, Facultad de Ciencias Químicas, Universidad Complutense, Madrid 28040, Spain

³ Faculty of Chemistry, Belarusian State University, Minsk 220030, Belarus

⁴ Faculty of Engineering, Kiel University, Kaiserstraße 2, 24143 Kiel, Germany

Coatings 2017, 7(11), 190; https://doi.org/10.3390/coatings7110190 - 6 Nov 2017

Cited by 29 | Viewed by 6010

Abstract

Plasma electrolytic oxidation (PEO) is an environmentally friendly anodizing technique leading to the formation of a ceramic-like coatings under high-voltage discharges. Layered double hydroxides (LDHs) were grown directly on γ, α, and amorphous Al₂O₃ powders, respectively, in order to investigate [...] Read more.

Plasma electrolytic oxidation (PEO) is an environmentally friendly anodizing technique leading to the formation of a ceramic-like coatings under high-voltage discharges. Layered double hydroxides (LDHs) were grown directly on γ, α, and amorphous Al₂O₃ powders, respectively, in order to investigate the phase responsible for in-situ LDH growth on PEO coating. Furthermore, it is shown that LDH growth is limited by the high tortuosity of the PEO layer and the accessibility of

{Al (OH)}_{4}^{-}

anions from the substrate covered with thin amorphous aluminum oxide, through the pores. Full article

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10 pages, 5927 KiB

Open AccessArticle

Ta–Zr–N Thin Films Fabricated through HIPIMS/RFMS Co-Sputtering

by Li-Chun Chang^1,2,*, Ching-Yen Chang¹ and Ya-Wen You¹

¹ Department of Materials Engineering, Ming Chi University of Technology, New Taipei City 24301, Taiwan

² Center for Thin Film Technologies and Applications, Ming Chi University of Technology, New Taipei City 24301, Taiwan

Coatings 2017, 7(11), 189; https://doi.org/10.3390/coatings7110189 - 4 Nov 2017

Cited by 8 | Viewed by 5172

Abstract

Ta–Zr–N thin films were fabricated through co-deposition of radio-frequency magnetron sputtering and high-power impulse magnetron sputtering (HIPIMS/RFMS co-sputtering). The oxidation resistance of the fabricated films was evaluated by annealing the samples in a 15-ppm O₂-N₂ atmosphere at 600 °C for [...] Read more.

Ta–Zr–N thin films were fabricated through co-deposition of radio-frequency magnetron sputtering and high-power impulse magnetron sputtering (HIPIMS/RFMS co-sputtering). The oxidation resistance of the fabricated films was evaluated by annealing the samples in a 15-ppm O₂-N₂ atmosphere at 600 °C for 4 and 8 h. The mechanical properties and surface roughness of the as-deposited and annealed thin films were evaluated. The results indicated that the HIPIMS/RFMS co-sputtered Ta–Zr–N thin films exhibited superior mechanical properties and lower surface roughness than did the conventional direct current-sputtered Ta–Zr–N thin films and HIPIMS-fabricated ZrN_x thin films in both the as-deposited and annealed states. Full article

(This article belongs to the Special Issue Thin Film Deposition and Characterization Techniques)

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14 pages, 4033 KiB

Open AccessArticle

Determining the Presence of Spalted Wood in Spanish Marquetry Woodworks of the 1500s through the 1800s

by Patricia T. Vega Gutierrez^*

and Seri C. Robinson

Department of Wood Science & Engineering, Oregon State University, Corvallis, OR 97331, USA

Coatings 2017, 7(11), 188; https://doi.org/10.3390/coatings7110188 - 4 Nov 2017

Cited by 16 | Viewed by 9382

Abstract

The process of using fungal-colored wood (spalted wood) for marquetry and intarsia woodworks in Italy and Germany was very popular from the 1400–1600s, with some instances continuing as late as the 1800s. While spalted marquetry in these countries is relatively well documented, less [...] Read more.

The process of using fungal-colored wood (spalted wood) for marquetry and intarsia woodworks in Italy and Germany was very popular from the 1400–1600s, with some instances continuing as late as the 1800s. While spalted marquetry in these countries is relatively well documented, less is known about its use in other parts of Europe. One of the primary reasons for this lack of knowledge is the difficulty in identifying spalted wood, especially the blue-green variety produced from Chlorociboria species, from wood dyed with copper-based compounds or other synthetics. The most reliable testing method involves destructive sampling, where a small piece is taken from the work, the pigment extracted, and an analysis performed. Such sampling is simply not feasible, nor often allowed, on ancient artwork. To make a reliable, non-destructive identification of spalted wood, a visual method based on anatomical characteristics of spalted wood was developed to differentiate spalted wood from dyed wood. High-resolution pictures were taken from wooden artifacts containing blue-green colored wood in collections at the National Museum of Decorative Arts (MNAD), the Royal Site Monastery El Escorial and the Bilbao Museum of Fine Arts in Spain. The concentration of pigment in the rays, the color distribution, the size of the piece and the date of production, were analyzed. With the use of this new visual method, it was possible to determine that intarsia artifacts, held in Spain but of Augsburg origin from the 1500–1600s, contained spalted wood details. Meanwhile, Spanish and Italian intarsia artifacts from the 1800s were found to only contain dyed wood. Full article

(This article belongs to the Special Issue Varnishes and Surface Treatments of Historical Wooden Artworks)

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16 pages, 10504 KiB

Open AccessArticle

Tribological and Wear Performance of Carbide Tools with TiB₂ PVD Coating under Varying Machining Conditions of TiAl6V4 Aerospace Alloy

by Jose Mario Paiva^1,2,*

, Mohamed Abdul Monim Shalaby³, Mohammad Chowdhury¹, Lev Shuster⁴, Sergey Chertovskikh⁴, Danielle Covelli⁵, Edinei Locks Junior¹, Pietro Stolf¹, Amr Elfizy⁶, Carlos Alberto Schuch Bork^1,7, German Fox-Rabinovich¹ and Stephen Clarence Veldhuis¹

¹ McMaster Manufacturing Research Institute (MMRI), Department of Mechanical Engineering, McMaster University, 1280 Main Street West, Hamilton, ON L8S4L7, Canada

² Department of Mechanical and Materials Science, Catholic University of Santa Catarina, Rua Visconde de Taunay, 427-Centro, Joinville-SC 89203-005, Brazil

³ Department of Design and Production, Technical Research Center, Cairo 11461, Egypt

⁴ Department of Mechanical Engineering, Ufa State Aviation Technical University (USATU), Ufa 450008, The Republic of Bashkortostan, Russian Federation

⁵ Biointerfaces Institute, McMaster University, ETB 422, 1280 Main Street West, Hamilton, ON L8S0A3, Canada

⁶ 1000 Marie-Victorin Blvd., Longueuil, QC J4G1A1, Canada

⁷ Instituto Federal de Educação, Ciência e Tecnologia Sul Riograndense (IFSul)—Campus Sapucaia do Sul, Piratini CEP 93216-120, Brazil

Coatings 2017, 7(11), 187; https://doi.org/10.3390/coatings7110187 - 4 Nov 2017

Cited by 29 | Viewed by 7115

Abstract

Tribological phenomena and tool wear mechanisms during machining of hard-to-cut TiAl6V4 aerospace alloy have been investigated in detail. Since cutting tool wear is directly affected by tribological phenomena occurring between the surfaces of the workpiece and the cutting tool, the performance of the [...] Read more.

Tribological phenomena and tool wear mechanisms during machining of hard-to-cut TiAl6V4 aerospace alloy have been investigated in detail. Since cutting tool wear is directly affected by tribological phenomena occurring between the surfaces of the workpiece and the cutting tool, the performance of the cutting tool is strongly associated with the conditions of the machining process. The present work shows the effect of different machining conditions on the tribological and wear performance of TiB₂-coated cutting tools compared to uncoated carbide tools. FEM modeling of the temperature profile on the friction surface was performed for wet machining conditions under varying cutting parameters. Comprehensive characterization of the TiB₂ coated vs. uncoated cutting tool wear performance was made using optical 3D imaging, SEM/EDX and XPS methods respectively. The results obtained were linked to the FEM modeling. The studies carried out show that during machining of the TiAl6V4 alloy, the efficiency of the TiB₂ coating application for carbide cutting tools strongly depends on cutting conditions. The TiB₂ coating is very efficient under roughing at low speeds (with strong buildup edge formation). In contrast, it shows similar wear performance to the uncoated tool under finishing operations at higher cutting speeds when cratering wear predominates. Full article

(This article belongs to the Special Issue Coatings for Cutting Tools)

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16 pages, 9585 KiB

Open AccessArticle

Study on the Formation of Reaction Phase to Si Addition in Boron Steel Hot-Dipped in Al–7Ni Alloy

by Jung-Gil Yun¹, Jae-Hyeong Lee², Sung-Yun Kwak² and Chung-Yun Kang^2,*

¹ Department of Hybrid Materials & Machining Technology, Graduate School of Convergence Science, Pusan National University, Busan 46241, Korea

² Department of Material Science and Engineering, Pusan National University, Busan 46241, Korea

Coatings 2017, 7(11), 186; https://doi.org/10.3390/coatings7110186 - 4 Nov 2017

Cited by 10 | Viewed by 4964

Abstract

In order to reduce the intermetallic compounds formed during the application of an Al–7Ni wt % hot-dip multifunctional coating on boron steel, developed for Tailor Welded Blanks (TWB) and hot stamping, 2–6 wt % Si was added to the coating to change the [...] Read more.

In order to reduce the intermetallic compounds formed during the application of an Al–7Ni wt % hot-dip multifunctional coating on boron steel, developed for Tailor Welded Blanks (TWB) and hot stamping, 2–6 wt % Si was added to the coating to change the reaction layer. The coating was run at 690 °C for 120 s. Al₉FeNi phases were formed on the steel interface, Fe₂Al₅ was formed on the steel, FeAl₃ was generated between the existing layers, and flake-type Al₂Fe₃Si₃ was formed in the Fe₂Al₅ phase, depending on the Si content. In addition, as Si was added to the coating, the thickness of the Fe₂Al₅ phase decreased and the thickness of the Al₉FeNi phase and Al₂Fe₃Si₃ increased. The decrease in the thickness of the Fe₂Al₅ phase was mainly due to the effect of the Si solid solution and the Al₂Fe₃Si₃ formation in the Fe₂Al₅ phase. The reason for the growth of Al₉FeNi is that the higher the Si content in the coating, the more the erosion of the interface of the steel material due to the coating solution. Therefore, the outflow of Fe into the coating liquid increased. Full article

(This article belongs to the Special Issue Innovative Coatings for Automotive Industry)

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18 pages, 12321 KiB

Open AccessReview

Surface Texturing of CVD Diamond Assisted by Ultrashort Laser Pulses

by Daniele M. Trucchi^1,*

, Alessandro Bellucci¹

, Marco Girolami¹

, Matteo Mastellone¹

and Stefano Orlando²

¹ DiaTHEMA Lab, Istituto di Struttura della Materia (ISM-CNR), Montelibretti Section, 00015 Monterotondo Scalo (RM), Italy

² Istituto di Struttura della Materia (ISM-CNR), Tito Scalo Section, Zona Industriale, 85050 Tito Scalo (PZ), Italy

Coatings 2017, 7(11), 185; https://doi.org/10.3390/coatings7110185 - 3 Nov 2017

Cited by 56 | Viewed by 7826

Abstract

Diamond is a wide bandgap semiconductor with excellent physical properties which allow it to operate under extreme conditions. However, the technological use of diamond was mostly conceived for the fabrication of ultraviolet, ionizing radiation and nuclear detectors, of electron emitters, and of power [...] Read more.

Diamond is a wide bandgap semiconductor with excellent physical properties which allow it to operate under extreme conditions. However, the technological use of diamond was mostly conceived for the fabrication of ultraviolet, ionizing radiation and nuclear detectors, of electron emitters, and of power electronic devices. The use of nanosecond pulse excimer lasers enabled the microstructuring of diamond surfaces, and refined techniques such as controlled ablation through graphitization and etching by two-photon surface excitation are being exploited for the nanostructuring of diamond. On the other hand, ultrashort pulse lasers paved the way for a more accurate diamond microstructuring, due to reduced thermal effects, as well as an effective surface nanostructuring, based on the formation of periodic structures at the nanoscale. It resulted in drastic modifications of the optical and electronic properties of diamond, of which “black diamond” films are an example for future high-temperature solar cells as well as for advanced optoelectronic platforms. Although experiments on diamond nanostructuring started almost 20 years ago, real applications are only today under implementation. Full article

(This article belongs to the Special Issue Diamond and Diamond-Like Coatings: Deposition, Characterization, and Applications)

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15 pages, 4193 KiB

Open AccessArticle

Biodegradable Ceramics Consisting of Hydroxyapatite for Orthopaedic Implants

by Thomas K. Monsees¹

, Funda Ak Azem², Cosmin Mihai Cotrut^3,4, Mariana Braic⁵, Radwan Abdulgader¹, Iulian Pana⁵, Isil Birlik², Adrian Kiss⁵, Robin Booysen¹ and Alina Vladescu^4,5,*

¹ Department of Medical Biosciences, University of the Western Cape, Bellville 7535, South Africa

² Metallurgical and Materials Engineering Department, Engineering Faculty, Dokuz Eylul University, Tinaztepe Campus, Izmir 35397, Turkey

³ Faculty of Material Science and Engineering, University Politehnica of Bucharest, 313 Spl. Independentei, Bucharest 060042, Romania

⁴ Department of Experimental Physics, National Research Tomsk Polytechnic University, Lenin Avenue 43, Tomsk 634050, Russia

⁵ National Institute for Optoelectronics, 409 Atomistilor St., Magurele 77125, Romania

Coatings 2017, 7(11), 184; https://doi.org/10.3390/coatings7110184 - 3 Nov 2017

Cited by 18 | Viewed by 6078

Abstract

This study aims to analyze hydroxyapatite (HAP) coatings enriched with Mg and Ti prepared by a magnetron sputtering technique on Ti6Al4V substrate. For preparation of the coatings, three magnetron targets (HAP, MgO and TiO₂) were simultaneously co-worked. The concentration of Mg [...] Read more.

This study aims to analyze hydroxyapatite (HAP) coatings enriched with Mg and Ti prepared by a magnetron sputtering technique on Ti6Al4V substrate. For preparation of the coatings, three magnetron targets (HAP, MgO and TiO₂) were simultaneously co-worked. The concentration of Mg added was varied by modifying the power applied to the MgO target. In all coatings, the Ti concentration was maintained constant by keeping the same cathode power fed during the whole deposition. The influence of different Mg dopant contents on the formation of phase, microstructure and morphology of the obtained Ti-doped HAP coatings were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Moreover, the effects of Mg addition upon corrosion, mechanical and biological properties were also investigated. Mg- and Ti-doped HAP coating obtained at low radio-frequency (RF) power fed to the MgO target provided material with high corrosion resistance compared to other coatings and bare alloy. A slight decrease in hardness of the coatings was found after the Mg addition, from 8.8 to 5.7 GPa. Also, the values of elastic modulus were decreased from 87 to 53 GPa, this being an advantage for biomedical applications. The coatings with low Mg concentration proved to have good deformation to yielding and higher plastic properties. Biological test results showed that the novel surfaces exhibited excellent properties for the adhesion and growth of bone cells. Moreover, early adherent vital cell numbers were significantly higher on both coatings compared to Ti6Al4V, suggesting that Mg ions may accelerate initial osteoblast adhesion and proliferation. Full article

(This article belongs to the Special Issue Advanced Biomimetic Calcium Phosphate Coatings)

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9 pages, 5133 KiB

Open AccessArticle

Characterization of Barnyard Millet Starch Films Containing Borage Seed Oil

by Thi Luyen Cao, So-Young Yang and Kyung Bin Song^*

Department of Food Science and Technology, Chungnam National University, Daejeon 34134, Korea

Coatings 2017, 7(11), 183; https://doi.org/10.3390/coatings7110183 - 1 Nov 2017

Cited by 24 | Viewed by 7089

Abstract

In this study, barnyard millet starch (BMS) was used to prepare edible films. Antioxidant activity was conferred to the BMS film by incorporating borage seed oil (BO). The physical, optical, and thermal properties as well as antioxidant activities of the films were evaluated. [...] Read more.

In this study, barnyard millet starch (BMS) was used to prepare edible films. Antioxidant activity was conferred to the BMS film by incorporating borage seed oil (BO). The physical, optical, and thermal properties as well as antioxidant activities of the films were evaluated. The incorporation of BO into the BMS films decreased the tensile strength from 9.46 to 4.69 MPa and increased the elongation at break of the films from 82.49% to 103.87%. Water vapor permeability, water solubility, and moisture content of the BMS films decreased with increasing BO concentration, whereas Hunter b value and opacity increased, L and a values of the films decreased. The BMS films containing BO exhibited antioxidant activity that increased proportionally with increased BO concentration. In particular, the BMS film with 1.0% BO exhibited the highest antioxidant activity and light barrier properties among the BMS films. Therefore, the BMS films with added BO can be used as an antioxidant packaging material. Full article

(This article belongs to the Special Issue Films and Coatings for Food and Health Applications)

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17 pages, 12946 KiB

Open AccessArticle

Microwave-Assisted Dip Coating of Aloe Vera on Metallocene Polyethylene Incorporated with Nano-Rods of Hydroxyapaptite for Bone Tissue Engineering

by Hairong Wang¹, Xueliang Zhang², Mohan Prasath Mani³, Saravana Kumar Jaganathan^4,5,6,*, Yi Huang¹ and Chengzheng Wang¹

¹ Department of Orthopedics, Jianhu Hospital Affiliated to Nantong University, Yancheng 224700, China

² Department of Orthopedics, First Hospital of Lanzhou University, Lanzhou 730000, China

³ Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, Johor Bahru 81300, Malaysia

⁴ Department for Management of Science and Technology Development, Ton Duc Thang University, Ho Chi Minh City, Vietnam

⁵ Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Vietnam

⁶ IJN-UTM Cardiovascular Engineering Centre, Department of Clinical Sciences, Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, Johor Bahru 81300, Malaysia

Coatings 2017, 7(11), 182; https://doi.org/10.3390/coatings7110182 - 31 Oct 2017

Cited by 10 | Viewed by 6864

Abstract

Bone tissue engineering widely explores the use of ceramic reinforced polymer-matrix composites. Among the various widely-used ceramic reinforcements, hydroxyapatite is an undisputed choice due to its inherent osteoconductive nature. In this study, a novel nanocomposite comprising metallocene polyethylene (mPE) incorporated with nano-hydroxyapaptite nanorods [...] Read more.

Bone tissue engineering widely explores the use of ceramic reinforced polymer-matrix composites. Among the various widely-used ceramic reinforcements, hydroxyapatite is an undisputed choice due to its inherent osteoconductive nature. In this study, a novel nanocomposite comprising metallocene polyethylene (mPE) incorporated with nano-hydroxyapaptite nanorods (mPE-nHA) was synthesized and dip coated with Aloe vera after subjecting it to microwave treatment. The samples were characterized using contact angle, Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), atomic force microscopy (AFM) and 3D Hirox microscopy scanning. Contact angle results show that the hydrophilicity of mPE-nHA improved notably with the coating of Aloe vera. The surface topology and increase in surface roughness were observed using the SEM, AFM and 3D Hirox microscopy. Blood compatibility assays of pure mPE and the Aloe vera coated nanocomposite were performed. The prothrombin time (PT) was delayed by 1.06% for 24 h Aloe-vera-treated mPE-nHA compared to the pristine mPE-nHA. Similarly, the 24 h Aloe-vera-coated mPE-nHA nanocomposite prolonged the activated partial thromboplastin time (APTT) by 41 s against the control of pristine mPE-nHA. The hemolysis percentage was also found to be the least for the 24 h Aloe-vera-treated mPE-nHA which was only 0.2449% compared to the pristine mPE-nHA, which was 2.188%. To conclude, this novel hydroxyapatite-reinforced, Aloe-vera-coated mPE with a better mechanical and anti-thrombogenic nature may hold a great potential to be exploited for bone tissue engineering applications. Full article

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12 pages, 1834 KiB

Open AccessArticle

Inhibitory Properties of Neomycin Thin Film Formed on Carbon Steel in Sulfuric Acid Solution: Electrochemical and AFM Investigation

by Adriana Samide^1,*, Gabriela Eugenia Iacobescu², Bogdan Tutunaru¹

, Roxana Grecu¹, Cristian Tigae¹ and Cezar Spînu¹

¹ Department of Chemistry, Faculty of Sciences, University of Craiova, Calea Bucuresti 107i, Craiova 200478, Romania

² Department of Physics, Faculty of Sciences, University of Craiova, A.I. Cuza No. 1, Craiova 200585, Romania

Coatings 2017, 7(11), 181; https://doi.org/10.3390/coatings7110181 - 31 Oct 2017

Cited by 29 | Viewed by 6335

Abstract

Our study aims to implement a strategy to reduce the carbon steel corrosion rate in a sulfuric acid solution, using an expired drug with adsorption affinity on the metal surface. To investigate the corrosion protection efficiency of an environmental friendly inhibitor, namely neomycin [...] Read more.

Our study aims to implement a strategy to reduce the carbon steel corrosion rate in a sulfuric acid solution, using an expired drug with adsorption affinity on the metal surface. To investigate the corrosion protection efficiency of an environmental friendly inhibitor, namely neomycin sulfate (NMS), the electrochemical measurements were applied on carbon steel immersed in 1.0 M H₂SO₄ solution with and without NMS. The protective layer that formed on the steel surface was studied by atomic force microscopy (AFM). The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) showed that the presence of the neomycin sulfate in acid solution leads to the decrease in corrosion current density (i_corr) and the increase of polarization resistance (R_p). The mixed mechanism between physical and chemical adsorption of NMS molecules on the steel surface was proposed according to the Langmuir adsorption isotherm. AFM indicated that the NMS molecules contributed to a protective layer formation by their adsorption on the steel surface. The AFM parameters, such as root mean square roughness (R_q), average roughness (R_a), and maximum peak to valley height (R_p−v) revealed that in the presence of NMS a smoother surface of carbon steel was obtained, compared to the steel surface corroded in sulfuric acid blank solution. Full article

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16 pages, 5530 KiB

Open AccessArticle

Evaluation of Accelerated Ageing Tests for Metallic and Non-Metallic Graffiti Paints Applied to Stone

by Patricia Sanmartín^1,*

and Francesca Cappitelli²

¹ Departamento de Edafoloxía e Química Agrícola, Facultade de Farmacia, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain

² Dipartimento di Scienze per gli Alimenti, la Nutrizione e l’Ambiente-DeFENS, Università degli Studi di Milano, Via Celoria 2, 20133 Milano, Italy

Coatings 2017, 7(11), 180; https://doi.org/10.3390/coatings7110180 - 30 Oct 2017

Cited by 18 | Viewed by 6692

Abstract

Graffiti are increasingly observed on urban and peri-urban buildings and their removal requires a huge financial outlay by local governments and agencies. Graffiti are not usually removed immediately, but rather over the passage of time, viz. months or even years. In this study, [...] Read more.

Graffiti are increasingly observed on urban and peri-urban buildings and their removal requires a huge financial outlay by local governments and agencies. Graffiti are not usually removed immediately, but rather over the passage of time, viz. months or even years. In this study, which forms part of a wider research project on graffiti removal, different methods (gravimetric analysis, examination of digital images, colour and infrared measurements) were used to evaluate the performance of accelerated ageing tests (involving exposure to humidity, freeze-thawing cycles and NaCl and Na₂SO₄ salts) for graffiti painted on stone. Silver (metallic) and black (non-metallic) graffiti spray paints were applied to two types of igneous rock (granite and rhyolitic ignimbrite) and one sedimentary rock (fossiliferous limestone, i.e., biocalcarenite). The metallic and non-metallic graffiti spray paints acted differently on the stone surfaces, both chemically and physically. Older graffiti were found to be more vulnerable to weathering agents. The ageing test with NaCl and particularly Na₂SO₄, both applied to granite, proved the most severe on the paints, yielding more detrimental and faster artificial ageing of the type of material under study. Full article

(This article belongs to the Special Issue Anti-Graffiti Coatings)

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13 pages, 2571 KiB

Open AccessArticle

Aluminum Templates of Different Sizes with Micro-, Nano- and Micro/Nano-Structures for Cell Culture

by Ming-Liang Yen¹, Hao-Ming Hsiao², Chiung-Fang Huang^3,4, Yi Lin⁵, Yung-Kang Shen^3,6,*

, Yu-Liang Tsai^6,7, Chun-Wei Chang⁸, Hsiu-Ju Yen⁹, Yi-Jung Lu⁹ and Yun-Wen Kuo⁹

¹ Division of Oral and Maxillofacial Surgery, Department of Dentistry, Taipei Medical University Hospital, Taipei 10617, Taiwan

² Department of Mechanical Engineering, National Taiwan University, Taipei 10617, Taiwan

³ School of Dental Technology, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan

⁴ Department of Dentistry, Taipei Medical University Hospital, Taipei 110, Taiwan

⁵ Department of Business Administration, Takming University of Science and Technology, Taipei 114, Taiwan

⁶ Research Center for Biomedical Devices, Taipei Medical University, Taipei 110, Taiwan

⁷ Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan

⁸ Division of Endodontic, Department of Dentistry, Taipei Medical University Hospital, Taipei 10617, Taiwan

⁹ Division of Family and Operative Dentistry, Department of Dentistry, Taipei Medical University Hospital, Taipei 10617, Taiwan

Coatings 2017, 7(11), 179; https://doi.org/10.3390/coatings7110179 - 26 Oct 2017

Cited by 4 | Viewed by 6572

Abstract

This study investigates the results of cell cultures on aluminum (Al) templates with flat-structures, micro-structures, nano-structures and micro/nano-structures. An Al template with flat-structure was obtained by electrolytic polishing; an Al template with micro-structure was obtained by micro-powder blasting; an Al template with nano-structure [...] Read more.

This study investigates the results of cell cultures on aluminum (Al) templates with flat-structures, micro-structures, nano-structures and micro/nano-structures. An Al template with flat-structure was obtained by electrolytic polishing; an Al template with micro-structure was obtained by micro-powder blasting; an Al template with nano-structure was obtained by aluminum anodization; and an Al template with micro/nano-structure was obtained by micro-powder blasting and then anodization. Osteoblast-like cells were cultured on aluminum templates with various structures. The microculture tetrazolium test assay was utilized to assess the adhesion, elongation, and proliferation behaviors of cultured osteoblast-like cells on aluminum templates with flat-structures, micro-structures, nano-structures, and micro/nano-structures. The results showed that the surface characterization of micro/nano-structure of aluminum templates had superhydrophilic property, and these also revealed that an aluminum template with micro/nano-structure could provide the most suitable growth situation for cell culture. Full article

(This article belongs to the Special Issue Surface Engineering of Biomaterials)

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11 pages, 5056 KiB

Open AccessArticle

Evolution of Nanostructure and Metastable Phases at the Surface of a HCPEB-Treated WC-6% Co Hard Alloy with Increasing Irradiation Pulse Numbers

by Yue Zhang^1,*

, Fuyang Yu¹, Shengzhi Hao^2,*, Fuyu Dong¹, Yang Xu³, Wubin Geng¹, Nannan Zhang¹

, Nathalie Gey⁴, Thierry Grosdidier⁴ and Chuang Dong²

¹ School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China

² Key Laboratory of Materials Modification & School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China

³ College of Materials Science and Engineering, Liaoning Technical University, Fuxin 123000, China

⁴ Laboratoire d’Etude des Microstructures et de Mécanique des Matériaux (LEM3), Université de Lorraine, CNRS UMR 7239, Ile du Saulcy, 57045 Metz, France

Coatings 2017, 7(11), 178; https://doi.org/10.3390/coatings7110178 - 26 Oct 2017

Cited by 11 | Viewed by 4415

Abstract

This work investigates the mechanisms of the microstructure evolution in the melted surface layers of a WC-6% Co hard alloy when increasing the number of pulses of irradiation by high-current pulsed electron beam (HCPEB) treatment. After one pulse of irradiation, about 50% of [...] Read more.

This work investigates the mechanisms of the microstructure evolution in the melted surface layers of a WC-6% Co hard alloy when increasing the number of pulses of irradiation by high-current pulsed electron beam (HCPEB) treatment. After one pulse of irradiation, about 50% of the stable hcp WC phase was melted and resolidified into the metastable fcc form (WC_1−x). When increasing the numbers of pulse irradiation, the WC phase decomposed into ultrafine-grained WC_1−x plus nanosized graphite under our selected energy condition. Because of the rapidity of HCPEB carried under vacuum, the formation of the brittle W₂C phase was avoided. In the initial Co-rich areas, where the Co was evaporated, melting and solidification led to the formation of nanostructures Co₃W₉C₄ and Co₃W₃C. The volume fraction of the nano domains containing WC_1−x, Co₃W₉C₄, and Co₃W₃C phases reached its maximum after 20 pulses of irradiation. The improved properties after 20 pulses are therefore due to the presence of nano graphite that served as lubricant and dramatically decreased the friction coefficient, while the ultrafine-grained carbides and the nano domains contribute to the improvement of the surface microhardness and wear resistance. Full article

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Coatings, Volume 7, Issue 11 (November 2017) – 30 articles

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