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Volume 1, Stand Alone Papers 2020

Mater. Proc., 2020, CIWC-2 2020

2nd Coatings and Interfaces Web Conference (CIWC-2 2020)

Online | 15-31 May 2020

Volume Editors:

Dr. Alessandro Lavacchi, Conference Secretariat

Prof. Dr. Andriy Voronov, Conference Secretariat

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Cover Story (view full-size image): The 2nd Coatings and Interfaces Web Conference (CIWC-2 2020) took place online from May 15 to May 31 2020. We received many excellent contributions, covering the fundamentals and the applications of [...] Read more.
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Research

Open AccessProceedings
Fabrication of Transparent ITO/Ga-Doped ZnO Coating as a Front Panel Electrode toward Efficient Thin Film Solar Cells
Mater. Proc. 2020, 2(1), 1; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06831 - 13 May 2020
Cited by 1 | Viewed by 287
Abstract
Bi-layer coatings from sputtered indium tin oxide (ITO) and gallium doped zinc oxide (Ga:ZnO) were investigated for transparency in the visible range of the electromagnetic spectrum, optical rejection ability in the near infrared spectrum and conductivity for the novel quantum dot-based solar cells. [...] Read more.
Bi-layer coatings from sputtered indium tin oxide (ITO) and gallium doped zinc oxide (Ga:ZnO) were investigated for transparency in the visible range of the electromagnetic spectrum, optical rejection ability in the near infrared spectrum and conductivity for the novel quantum dot-based solar cells. The multilayer stack produced at optimal oxygen partial pressure exhibits improved optical properties without worsening the electrical ones, even after additional oxidation during the reactive sputtering of the metal-oxides. With a mean optical transmittance of 91.3% in the visible region, mean optical rejection greater than 65% in the infrared range and resistivity lower than 0.4 × 10−2 Ω.cm, this coating is good candidate for front panel electrode in the CdS/ZnS core-shell quantum dot-based solar cells. Full article
Open AccessAbstract
Encapsulated Microbial Propionic Acid as Additive for Texture-Defined Bread
Mater. Proc. 2020, 2(1), 2; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06834 - 14 May 2020
Viewed by 330
Abstract
The main goal of the ELBE-NH (Increased effectiveness of lignin-biorefineries by valorization of hydrolysates) project funded by the Federal Ministry of Education and Research (BMBF), Germany, is the utilization of the by-products of lignocellulosic biorefinery as high valuable compounds. One of the targeted [...] Read more.
The main goal of the ELBE-NH (Increased effectiveness of lignin-biorefineries by valorization of hydrolysates) project funded by the Federal Ministry of Education and Research (BMBF), Germany, is the utilization of the by-products of lignocellulosic biorefinery as high valuable compounds. One of the targeted compounds selected is propionic acid (PA) (obtained by microbiological conversion of the hydrolysates). PA is particularly suitable for use in industrially produced bread and baked goods, for preservation (antifungal abilities) as free acid or as sodium/calcium salts. Due to its astringent smell and strong acid taste, PA is rarely used in the food industry as a free acid. Our aim is to test the possibility of (a) using encapsulated hydrophilic PA (0.3% w/v) in β-cyclodextrin (β-CD)/maltodextrin blends as the wall materials (19:1 or 17:3% w/v), spray-dried as additives incorporated directly into texture-defined bread products, and (b) incorporating it into polysaccharide-based (e.g., carboxymethylcellulose (2% w/v) or chitosan (2% w/v)) biodegradation-resistant edible film (as carriers of PA antimicrobial agent (1.5–15% w/v)) with/without addition of β-CD (5% w/v) to the film matrix, as packaging material to enhance the safety and shelf life of texture-defined bread products. The benefit of adding β-CD during film preparation consists in the forming of hydrogen bond interactions with PA, resulting in high amounts of PA encapsulation due to the “fully immersed” complexation phenomenon. The texture-defined bread is a bread with a soft, gel-like structure that is easy to swallow and can be consumed without chewing, intended for people suffering from swallowing and chewing disorders. The texture-defined bread will have a high protein content that is up to 15% higher than that of conventional bread and can thus make an important contribution to combating malnutrition. Full article
Open AccessProceedings
Influence of the Size of Coal Ash FAU Zeolites Used as Dopants on the Sensing Properties of Nb2O5 Thin Films
Mater. Proc. 2020, 2(1), 3; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06829 - 13 May 2020
Viewed by 231
Abstract
In this study, solid waste from coal combustion in thermal power plants (TPPs) was used for the synthesis of zeolite Na-X samples. They were prepared by the long-term alkaline atmospheric conversion of coal ash collected from the electrostatic precipitators in the TPP “AES [...] Read more.
In this study, solid waste from coal combustion in thermal power plants (TPPs) was used for the synthesis of zeolite Na-X samples. They were prepared by the long-term alkaline atmospheric conversion of coal ash collected from the electrostatic precipitators in the TPP “AES Galabovo”. When used in the form of thin films/layers, the optical detection of volatile organic compounds (VOCs) is possible due to a change in their reflectance spectra and color. In order to improve the sensing properties of synthesized zeolites, they were wet milled for 60 s and both milled and unmilled zeolites were used as dopants for the niobium oxide matrix in the form of thin films deposited by the spin-coating method on a silicon substrate. The surface morphology and structure of both zeolite powders were studied by scanning electron microscopy, while their size was determined by dynamic light scattering (DLS) spectra. Optical constants (refractive index, n, and extinction coefficient, k) and the thickness of the films were calculated from reflectance measurements. The change in the reflection coefficient ∆R of the films was determined from measured reflectance spectra prior to and after exposure to probe acetone molecules. An increase in the reaction of the films with milled zeolites to acetone, compared to the samples with unmilled zeolites, is demonstrated. Full article
Open AccessProceedings
Synthesis of Silica Particles from Sugarcane Bagasse Ash for Its Application in Hydrophobic Coatings
Mater. Proc. 2020, 2(1), 4; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06830 - 13 May 2020
Viewed by 296
Abstract
: Wastes such as sugarcane bagasse ash (SCBA) can be used as raw material in ceramics by the elaboration of bricks and tiles and the glass industry, due the high amount of silica in its composition (>70%). Another application for SCBA is the [...] Read more.
: Wastes such as sugarcane bagasse ash (SCBA) can be used as raw material in ceramics by the elaboration of bricks and tiles and the glass industry, due the high amount of silica in its composition (>70%). Another application for SCBA is the synthesis of metallic silicates. In this work, we study the synthesis of sodium silicate with SCBA as the main raw material and the future application of sodium silicate for the preparation of silica particles in order to create hydrophobic surfaces for ceramic materials to prevent their erosion. The sodium silicate synthesis was carried out by the thermochemical method with batches of ash and sodium carbonate in a 1:1 sodium oxide–silicon oxide molar ratio. The thermal treatment was in an electric furnace at 800 °C for 8 h. Then, for the synthesis of the silica particles, the sodium silicate was dissolved in water, and then we added methanol in a 3:2 water methanol volume ratio. The solution was left to age for an hour to create the Si-OH bond. Finally, tetraethylorthosilicate (TEOS) was added and the solution was stirred for 2 h to create a hydrophobic and hydrolytically resistant siloxane by the displacement of H in the Si-OH bond. The application of the solution was by the spray-coating method over substrates of concrete and red clay with the application of 10, 15, and 20 layers. The hydrophobicity was evaluated with the water contact angle test, with the results of contact angles above the 110°, thus demonstrating the capacity of a waste for the generation of coatings to prolong the useful life of building materials. Full article
Open AccessProceedings
Tannin Encapsulation for Personalized Product Applications
Mater. Proc. 2020, 2(1), 5; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06825 - 13 May 2020
Viewed by 313
Abstract
Tannins are the secondary metabolites of plants, and are polymers consisting mainly of glycosides, found in nature as hydrolysable tannins or condensed tannins, as well as a combination of them. In the European Horizon 2020-funded Stance4Health project, one of the objectives is to [...] Read more.
Tannins are the secondary metabolites of plants, and are polymers consisting mainly of glycosides, found in nature as hydrolysable tannins or condensed tannins, as well as a combination of them. In the European Horizon 2020-funded Stance4Health project, one of the objectives is to develop special tannin extracts (from chestnut wood, quebracho wood, oak wood, tara pods, Chinese gallnuts) with differential effects on the gut microbiota and human health, aiming for a personalized modulation of gut microbiota activity at the individual level. Full article
Open AccessProceedings
Surface and Morphological Features of ZrO2 Sol-Gel Coatings Obtained by Polymer Modified Solution
Mater. Proc. 2020, 2(1), 6; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06810 - 30 Apr 2020
Viewed by 306
Abstract
Thin, homogeneous ZrO2 films were obtained by spin coating method from ZrOCl2 8H2O solution, modified with polyethylene glycol (PEG) (Mw = 400). The films have thickness of 80 nm and refractive index of about 1.45, which varied with the [...] Read more.
Thin, homogeneous ZrO2 films were obtained by spin coating method from ZrOCl2 8H2O solution, modified with polyethylene glycol (PEG) (Mw = 400). The films have thickness of 80 nm and refractive index of about 1.45, which varied with the amount of added PEG. The thermal behaviour of the precursor was studied with thermogravimetry and differential thermal analysis (TG-DTA). The X-ray diffraction (XRD) analysis revealed the presence of a mixture of monoclinic and tetragonal ZrO2 polycrystalline phases with nanosized crystallites. The formation of hydrogen bonds among the organic and inorganic components was proved by means of Fourier transform infrared spectroscopy (FT-IR) analysis, while the different defect centres were investigated with electron paramagnetic resonance (EPR) spectroscopy. The scanning electron microscopy (SEM) images showed that the samples are dense and crack-free, with ganglia-like nanostructure. It was established that the addition of polymer resulted in the introduction of free volume in the films, which also varied with the content of PEG in the precursor solution. Full article
Open AccessAbstract
Surface Modification of Implants by Sol-Gel Coating Technology: Advantages and Applications
Mater. Proc. 2020, 2(1), 7; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06827 - 13 May 2020
Viewed by 284
Abstract
Nowadays, approximately 1.5 million joint replacements are performed annually in Europe, while 7 million are performed in the United States. Despite the advances made in the biomaterials field over the last 50 years, today the average lifetime of an implant is still about [...] Read more.
Nowadays, approximately 1.5 million joint replacements are performed annually in Europe, while 7 million are performed in the United States. Despite the advances made in the biomaterials field over the last 50 years, today the average lifetime of an implant is still about 20 years. This entails the need for subsequent prosthetic device replacement, especially in young patients, resulting in an increase in patients’ health risks as well as clinical and economic burdens for the public health service. The failure of the implants can be caused by several reasons, such as adverse immune system reaction, biofilm formation or mechanical, chemical, tribological, surgical, manufacturing and biocompatibility problems. An alternative and useful strategy used to overcome this limitation is the modification of the implants’ surface by sol-gel coating technology. It allows for the production of coatings with a wide range of properties on substrates of different nature and shape, due to the fine control of the coating composition and microstructure. Sol-gel coatings were successfully proposed to inhibit wear, reduce corrosion and ion release, and modify the lubricity, hydrophilicity/hydrophobicity, and functionality of several substrates. Moreover, many works report the application of sol-gel coatings on bio-inert implants to improve their bioactivity and biocompatibility, leading to the enhancement of the integration process. This is ascribable to the presence of residual hydroxyl groups on coating materials’ surface, able to induce easier nucleation of the hydroxyapatite to their mesoporosity and, thus, the large specific surface area. Furthermore, the low processing temperatures allow for easy coating functionalization by embedding suitable molecules such as anti-inflammatory and antibacterial agents leading to coatings preventing biofilm formation and inflammatory pathway activation. Therefore, the application of the sol-gel coatings provides an excellent chemical modification of the materials’ surface, allowing for protective barrier layer production. Full article
Open AccessProceedings
Hybrid Oxidation of Titanium Substrates for Biomedical Applications
Mater. Proc. 2020, 2(1), 8; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06845 - 15 May 2020
Viewed by 305
Abstract
Titanium oxidation for biomedical applications is still a challenge in obtaining favorable mechanical and physicochemical properties of thin oxide layers, as well as the required high bioactivity. Interesting techniques for TiO2 layer formation are electrochemical, plasma and diffusive methods. Each method aims [...] Read more.
Titanium oxidation for biomedical applications is still a challenge in obtaining favorable mechanical and physicochemical properties of thin oxide layers, as well as the required high bioactivity. Interesting techniques for TiO2 layer formation are electrochemical, plasma and diffusive methods. Each method aims to create a thin oxide layer characterized by thermal stability and re-passivation in the presence of a simulated body fluid SBF environment. However, an important aspect here is also the phase composition of oxide layers, essential for osseointegration. Accordingly, the research carried out aims to produce such a titanium substrate, where the surface zone is a Tiα(O) solid solution formed with fluidized bed (FB) diffusion process (640 °C, 8 h) and the top layer is TiO2 produced by physical vapour deposition PVD—magnetron sputtering. The effects of such hybrid oxidation on titanium surface properties were investigated with scanning electron microscopy SEM/scanning transmission electron microscopy STEM/ Raman spectroscopy RS and nanoindentation tests. The results showed that hybrid oxidation made it possible to generate a favorable synergetic effect between FB and PVD oxide layers and to reduce the stresses at their interface. In turn, a variable share of TiO2 phases (rutile + anatase mixture) obtained at the titanium surface allowed for the significant enhancement of hydroxyapatite compound growth, which was confirmed by a 14-day Kokubo test. Full article
Open AccessProceedings
New Advances in Fibroblast Growth Factor-Based Coatings for Hip Replacement Implants
Mater. Proc. 2020, 2(1), 9; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06844 - 15 May 2020
Viewed by 306
Abstract
It is already well known that the tissue–implant interface is one of the most critical factors for the success of implant integration. The use of bioactive and biomimetic surfaces is of great interest in biomedical applications, especially in tissue engineering. Therefore, in our [...] Read more.
It is already well known that the tissue–implant interface is one of the most critical factors for the success of implant integration. The use of bioactive and biomimetic surfaces is of great interest in biomedical applications, especially in tissue engineering. Therefore, in our study, we aimed to obtain successful coatings based on hydroxyapatite, antibiotics and growth factors in order to increase the biocompatibility of commercial implant materials by promoting cell attachment and growth without toxic effects, as well as the inhibition of microbial biofilm formation. In this way, homogenous mixtures of hydroxyapatite, kanamycin and fibroblast growth factor (HAP/KAN, HAP/FGF and HAP/KAN/FGF) were coated on titanium-based metal plates for hip replacement implants. The coatings were able to impair the initial adherence of bacterial cells and to reduce biofilm formation throughout the release of antibiotics. The cytocompatibility of these samples was investigated on normal murine osteoblasts (MC3T3-E1 cell line) with fibroblast-like morphologies by evaluating their influence on cellular viability and their potential to generate an inflammatory response. In addition, adhesion and proliferation, as well as actin cytoskeleton organization, were observed after 24 h of cell culture on these coatings. The results confirmed the biocompatibility of all coatings, with the cell number counted for the HAP/KAN/FGF sample being equal to the control. Since it is well known that NO is a marker of inflammation with an essential role in regulating apoptotic cell death and cell viability, our study showed that cell growth on these surfaces did not induce nitric oxide (NO) release, with the NO level being maintained close to control values for all tested samples. Moreover, an excellent cell adherence and spreading on these coatings deposited on hip implants was evidenced by fluorescence microscopy, supporting their usage as substrates in tissue engineering applications. Full article
Open AccessProceedings
N-Type Thermoelectric Textile Fabrics Based on Vapor Grown Carbon Nanofibers
Mater. Proc. 2020, 2(1), 10; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06828 - 13 May 2020
Viewed by 258
Abstract
Thermoelectric (TE) devices that convert a heat gradient directly into electricity are considered as a clean technology for energy harvesting. Both hole-transporting (p-type) and electron-transporting (n-type) materials are required in order to fabricate a thermoelectric module. Carbon nanotube (CNT)-based textile fabrics are relevant [...] Read more.
Thermoelectric (TE) devices that convert a heat gradient directly into electricity are considered as a clean technology for energy harvesting. Both hole-transporting (p-type) and electron-transporting (n-type) materials are required in order to fabricate a thermoelectric module. Carbon nanotube (CNT)-based textile fabrics are relevant in this context for the production of wearable TE modules due to the combination of the high electrical conductivity and thermopower (Seebeck coefficient) from the CNT and the low thermal conductivity and flexibility provided by the textile fabric [1]. Nevertheless, most as-produced CNTs are p-type materials due to their inherent oxygen doping, and therefore the production of air- and thermally stable n-type CNT-based textile fabrics remains a challenge nowadays [2]. On the other hand, vapor-grown carbon nanofibers (VGCNF), produced by chemical vapor deposition (CVD), have similar structures to multiwall carbon nanotubes (MWCNT), which make them valuable for electronic applications. For instance, by adjusting process variables during their CVD and post-growth heat treatment, VGCNF can be tailored to have a wide range of thermal conductivity and electrical conductivity at room temperature. In particular, the unexpected n-type character at room temperature that they supply to dip-coated cotton fabrics will be the issue of this presentation [3]. Full article
Open AccessProceedings
Study of Lead-Free Ferroelectric Composite Coatings by Impedance Spectroscopy
Mater. Proc. 2020, 2(1), 11; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06812 - 07 May 2020
Cited by 1 | Viewed by 245
Abstract
Abstract: The aim of the study is the preparation and electrical characterization of lead-free ferroelectric oxide BaSrTiO3 in the composition with a piezoelectric polymer. The properties of the deposited films were compared with pristine oxide. Atomic force microscopy showed a smooth [...] Read more.
Abstract: The aim of the study is the preparation and electrical characterization of lead-free ferroelectric oxide BaSrTiO3 in the composition with a piezoelectric polymer. The properties of the deposited films were compared with pristine oxide. Atomic force microscopy showed a smooth surface, and a regular and homogeneous distribution of particles of both components in the composite films. The dielectric properties (electric permittivity and dielectric loss) were investigated at different temperatures ranging from 5 to 130 °C. Impedance spectroscopy was applied in the frequency range 100–100 kHz. The dielectric constant increase with the addition of a piezoelectric polymer to the ceramic phase was demonstrated. It can be seen that the interface conditions at the electrodes are improved after inserting a piezoelectric polymer. The interpretation of the plots of the complex impedance vs. frequency, and the real part of the impedance vs. the imaginary part, give information about the polarization process revealed in the structures. Full article
Open AccessProceedings
Measuring the Thickness of Metal Films: A Selection Guide to the Most Suitable Technique
Mater. Proc. 2020, 2(1), 12; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06823 (registering DOI) - 13 May 2020
Viewed by 341
Abstract
The determination of thickness has a fundamental importance in all fields in which the implementation of films and coatings are required and takes a crucial role in the electroplating sector. The thickness influences many aspects of the coatings such as electrical, mechanical, corrosion [...] Read more.
The determination of thickness has a fundamental importance in all fields in which the implementation of films and coatings are required and takes a crucial role in the electroplating sector. The thickness influences many aspects of the coatings such as electrical, mechanical, corrosion protection, and even aesthetic properties. In the multitude of applications of thin layer coatings, the variability of thicknesses and materials is very high, as well as the variability of possible techniques that can be used to determine the characteristics of the layers of interest. The first distinction that can be made between these techniques is that which divides destructive techniques from non-destructive ones, in which, however, the semi- or micro-destructive techniques are immediately difficult to place. Other important parameters to consider are the cost, both for the purchase of the instrumentation and for each single analysis, the difficulties in preparing and measuring the sample, data processing, and obviously the detectable thickness ranges, the possible measurable materials, and precision and accuracy. The purpose of this work is to compare the characteristics of the various investigation methods, with a particular focus on metal film applications, so that it will be easier to choose the most suitable technique for each purpose. Full article
Open AccessProceedings
Impact Test Applications Supported by FEA Models in Surface Engineering for Coating Characterization
Mater. Proc. 2020, 2(1), 13; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06809 - 30 Apr 2020
Viewed by 229
Abstract
The impact test has been used for several years, among others, for characterizing the fatigue strength, creep, adhesion and residual stresses of coatings at ambient and elevated temperatures under dry or lubricated conditions. A major advantage of this test method is that in [...] Read more.
The impact test has been used for several years, among others, for characterizing the fatigue strength, creep, adhesion and residual stresses of coatings at ambient and elevated temperatures under dry or lubricated conditions. A major advantage of this test method is that in many cases, it can be employed directly on the coated parts and not on specimens. The obtained experimental results are evaluated by convenient finite element method (FEM)-supported algorithms. Based on these algorithms, critical data for predicting the life span of coated parts such as cutting tools and bearings and for planning appropriate replacements can be obtained. The paper provides an overview of the development of impact test devices, experimental techniques and result evaluation methods. Characteristic examples highlighting the quantification of the fatigue strength of PVD (Phyical Vapour Deposition) coatings and their adhesion via the critical equivalent and shear stresses, respectively, as well as that of the temperature-dependent interfacial fatigue strength of diamond coatings via the critical shear stress, are shown. Full article
Open AccessProceedings
Low-Cost Solar Heating Reservoir Manufactured by Double-Coating a Water Tank with Polymeric Materials
Mater. Proc. 2020, 2(1), 14; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06784 - 03 Apr 2020
Viewed by 317
Abstract
One of the main needs of the modern society is the availability of low-cost energy sources, and solar energy arises as an interesting alternative for both the generation of heat and electricity. In this work, a low-cost solar energy reservoir is proposed for [...] Read more.
One of the main needs of the modern society is the availability of low-cost energy sources, and solar energy arises as an interesting alternative for both the generation of heat and electricity. In this work, a low-cost solar energy reservoir is proposed for domestic water heating. It is comprised of a thermoplastic (polyethylene) water tank thermally insulated by means of two different polymeric coatings: an acrylonitrile butadiene rubber foam, NBR, and a metalized polyester layer. The solar system also contains a flat collector based on a ceiling panel made of poly(vinyl chloride) (PVC) coated with carbon black-filled glaze. The system design is cost effective because all of the parts involved in the solar heating are made from commodity plastic materials. These plastic components present wide commercial availability and are easily handled, so that they can be rapidly assembled to build the entire system. Therefore, the solar heating system is simple, modular, easily scalable, and may be even self-manufactured by the final user. It is an affordable option to the traditional high-cost copper, aluminum and glass solar panels, boilers or tanks used for heat storage. Full article
Open AccessProceedings
Electrical Investigation of the Mechanism of Water Adsorption/Desorption by Natural Clinoptilolite Desiccant Used in Food Preservation
Mater. Proc. 2020, 2(1), 15; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06800 - 21 Apr 2020
Cited by 1 | Viewed by 221
Abstract
Powdered zeolites are used as a desiccant in the preservation of many types of vegetable foods (e.g., cereal grain, corn, etc.). Natural clinoptilolite is a very abundant, inexpensive, nontoxic, regenerable, and environmentally friendly zeolite with good desiccant properties. Here, water adsorption/desorption properties of [...] Read more.
Powdered zeolites are used as a desiccant in the preservation of many types of vegetable foods (e.g., cereal grain, corn, etc.). Natural clinoptilolite is a very abundant, inexpensive, nontoxic, regenerable, and environmentally friendly zeolite with good desiccant properties. Here, water adsorption/desorption properties of natural clinoptilolite have been investigated by a novel technique based on a.c. electrical measurements. In particular, owing to the presence of extra-framework cations, zeolites are ionic conductors. The presence of water in cationic sites significantly modifies cation mobility, because strong electrostatic interactions act between cations and nucleophilic areas in 3D-frameworks, and non-hydrated cations have a near zero mobility, while hydrated cations have enough mobility at room temperature. The type of law controlling the adsorption/desorption process has been established by monitoring the real-time behavior of relative current intensity moving in the sample surface biased by a sinusoidal voltage signal of 20Vpp (5 kHz) and exposed to a constant moisture atmosphere (75%) at 25 °C. An intergranular diffusion control was active at the beginning of hydration because of the lamellar texture, then Lagergren irreversible pseudo-first-order kinetics took place. To confirm the adsorption mechanism and possibility of regenerating the clinoptilolite desiccant, dehydration by silica gel was electrically monitored and an exponential kinetic law found. Full article
Open AccessProceedings
Microstructural Refinement and Improvement of Microhardness of a Hypoeutectic Al–Fe Alloy Treated by Laser Surface Remelting
Mater. Proc. 2020, 2(1), 16; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06813 - 07 May 2020
Viewed by 296
Abstract
In laser surface remelting (LSR) treatment, only a small region is affected by heat, surpassing the melting temperature, followed by rapid cooling at 103–108 K/s, thus producing an extremely refined microstructure. The treated region shows a more homogeneous microstructure and [...] Read more.
In laser surface remelting (LSR) treatment, only a small region is affected by heat, surpassing the melting temperature, followed by rapid cooling at 103–108 K/s, thus producing an extremely refined microstructure. The treated region shows a more homogeneous microstructure and better mechanical properties as compared to the substrate. Iron is a common impurity found in Al-based alloys but in the 2618 commercial alloy, around 1 wt.% of Fe is intentionally added to improve the high temperature strength and the corrosion resistance. In this work, LSR experiments were performed, by using a CO2 laser operating in a continuous-wave mode, to investigate the influence of process parameters on the treated surface of an as-cast Al-1 wt.% Fe alloy. These parameters encompass work distance (z), laser beam speed (v) and laser average power (P), setting a total of 18 combinations. The configuration of z = 6 mm, v = 500 mm/s and P = 800 W resulted in a molten pool with 710 µm of width for 242 µm of length without major porosities, therefore being the largest stable pool amongst all parameter combinations. The resulting cellular microstructure is shown to have an average interphase spacing of 0.93 ± 0.17 µm, a decrease of about 14 times in relation to that of the substrate. The effects of LSR on microhardness were remarkable, with the remelted track presenting Vickers microhardness of 50.1 ± 2 HV, which corresponds to increase of about 43% as compared to that of the original substrate. Full article
Open AccessProceedings
NiOOH/FeOOH Supported on Reduced Graphene Oxide Composite Electrodes for Ethanol Electrooxidation
Mater. Proc. 2020, 2(1), 17; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06840 - 14 May 2020
Cited by 1 | Viewed by 368
Abstract
In this work, nickel (Ni) and Ni-Fe bimetallic microparticles were electrosynthesized at reduction potentials in the range from −0.70 V to −1.20 V (50 mV s−1) by cyclic voltammetry (CV) onto graphite/paraffin electrode surface modified with nanosheets of reduced graphene oxide [...] Read more.
In this work, nickel (Ni) and Ni-Fe bimetallic microparticles were electrosynthesized at reduction potentials in the range from −0.70 V to −1.20 V (50 mV s−1) by cyclic voltammetry (CV) onto graphite/paraffin electrode surface modified with nanosheets of reduced graphene oxide (RGO). Previously, the RGO was electrodeposited by CV from a suspension of 1 mg mL−1 of graphene oxide in PBS solution with pH 9.18, in the potential range from −1.50 V to 0.50 V (10 mV s−1). After electrodeposition of metals, the oxyhydroxides were formed by CV in an alkaline medium of 0.10 mol L−1 of NaOH in the potential range from −0.20 V to 1.0 V (100 mV s−1) with successive scans until stabilization of currents. In order to characterize the developed electrodes composites, the surfaces were investigated by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Electrochemical performance of the developed electrodes composites to ethanol electrooxidation was carried out in an alkaline medium of 0.10 mol L−1 of NaOH in the potential range from −0.20 V to 1.0 V (100 mV s−1) by CV. The electrodes were able to induce the electrooxidation of ethanol at a potential of 0.55 V for the electrode made of NiOOH/FeOOH and around of 0.60 V for the electrode modified with NiOOH. Full article
Open AccessProceedings
Natural Coatings on Titanium Surfaces to Improve Their Biological Response
Mater. Proc. 2020, 2(1), 18; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06835 - 14 May 2020
Viewed by 317
Abstract
Biomolecules and extracts from natural products are gaining increasing interest due to their beneficial properties for human health, low toxicity, environmental compatibility and sustainability. In this work, keratin, chitosan and peppermint essential oil have been used for the preparation of coatings on titanium [...] Read more.
Biomolecules and extracts from natural products are gaining increasing interest due to their beneficial properties for human health, low toxicity, environmental compatibility and sustainability. In this work, keratin, chitosan and peppermint essential oil have been used for the preparation of coatings on titanium substrates for biomedical implants/devices. All these coatings were obtained from local natural products/byproducts: keratin from discarded wool, chitosan from shrimp shells and peppermint essential oils from a local production. The above cited molecules were selected for their ability to stimulate soft tissue adhesion (keratin), anti-inflammatory activity (chitosan) and antibacterial activity (keratin after metal ion doping, chitosan and mint oil). The coatings were characterized by means of SEM-EDS, FTIR, zeta potential, wettability, tape and scratch tests, and cell and bacteria cultures. The coatings were successfully obtained for all the considered natural substances with good adhesion to the titanium substrates. All the coatings are chemically stable in water and the continuous coatings are mechanically resistant and protective for the metallic substrates. The keratin coatings are hydrophilic while the mint oil and chitosan coatings are hydrophobic; nanofibers, instead of continuous coatings, behave as more hydrophobic. At the physiological pH, the keratin and mint oil coatings are negatively charged when in contact with an aqueous environment, while the chitosan ones are positively charged. The oriented keratin fibers are able to drive fibroblast alignment. The Ag-doped keratin fibers and mint coating show antibacterial properties. Full article
Open AccessProceedings
Novel Coatings Based on Nanostructured Cefepime-Functionalized Magnetite for Implantable Devices
Mater. Proc. 2020, 2(1), 19; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06817 - 08 May 2020
Viewed by 212
Abstract
The aim of this study was to obtain biocompatible coatings based on polylactic acid, hydroxyapatite and nanostructured Cefepime-functionalized magnetite for enhancing the activity of next-generation implants against antibiotic-resistant pathogens. Mixtures of various ratios of polylactic acid, hydroxyapatite and nanostructured Cefepime-functionalized magnetite (Fe3 [...] Read more.
The aim of this study was to obtain biocompatible coatings based on polylactic acid, hydroxyapatite and nanostructured Cefepime-functionalized magnetite for enhancing the activity of next-generation implants against antibiotic-resistant pathogens. Mixtures of various ratios of polylactic acid, hydroxyapatite and nanostructured Cefepime-functionalized magnetite (Fe3O4@CEF, HAP/Fe3O4@CEF and PLA/Fe3O4@CEF) were obtained and deposited on glass slides by Matrix Assisted Pulsed Laser Evaporation (MAPLE). The in vitro biological effects of these coated surfaces on murine normal osteoblasts (MC3T3-E1 Subclone 4 (ATCC cat. no. CRL-2593)) were investigated by observing their morphological features and measuring the cell viability and nitric oxide (NO) release as an indicator of inflammation and cell death. A good biocompatibility was noticed for all samples investigated within this study, according to a formazan-based assay. Additionally, no increase in NO level was induced after 24 h of cell growth on these coated glass slides. Moreover, the visible microscopy images showed a good cell attachment on these modified surfaces and proved that the proliferative capacity of ostelasts was not disturbed in the presence of tested samples. The coatings succeeded in reducing the microbial attachment as well as the subsequent Escherichia coli colonization and biofilm development on these surfaces. In conclusion, these novel coatings can become suitable surfaces for implantable devices with an enhanced biocompatibility and reduced bacterial colonization. Full article
Open AccessProceedings
2D and 3D Electrospun Silk Fibroin Gelatin Coatings to Improve Scaffold Performances in Cardiovascular Applications
Mater. Proc. 2020, 2(1), 20; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06843 - 15 May 2020
Viewed by 299
Abstract
A coating with biomacromolecules can improve the performance of electrospun 3D scaffolds and 2D matrices that show morphology similar to that of native ECM, but their mechanical and biological properties are often inadequate, particularly in applications in contact with blood. In this work, [...] Read more.
A coating with biomacromolecules can improve the performance of electrospun 3D scaffolds and 2D matrices that show morphology similar to that of native ECM, but their mechanical and biological properties are often inadequate, particularly in applications in contact with blood. In this work, a gelatin coating was applied to electrospun silk fibroin (ESF) mats and tubes intended for the regeneration of cardiovascular tissues. The crosslinking reaction used is based on a Michael-type addition in water that promotes the formation of covalent bonds between gelatin amino groups and β-carbons of N-N′-methylene bis-acrylamide (MBA). ESF mats and tubes were coated with gelatin MBA crosslinked in situ by loading or dipping the ESF samples with the crosslinking solution by use of static or dynamic homemade systems. SEM analysis on coated samples showed a homogeneous coating with gelatin penetrating the whole thickness of the SF matrix (≈120 µm for mats and ≈212 µm for tubes), with an increase of thickness of about 40% in wet conditions. Water uptake tests indicated for coated samples a faster and higher swelling (1600% after 14 days) than not coated ones (500%), due to the presence of gelatin. Tensile mechanical tests showed higher values of ultimate stress and elastic modulus for silk fibroin samples (b = 2.4, E = 1.82 MPa) compared to gelatin-coated ones (b = 1.2, E = 0.58 MPa), with not significant differences in the ultimate deformation (≈150%). Indirect cytocompatibility tests, performed by culturing L929 cells in the presence of eluates obtained by immersing coated and uncoated samples up to 7 days in culture medium, demonstrated a cell viability higher than the control. For direct contact tests, primary human umbilical vein endothelial cell (HUVEC), obtained by enzymatic digestion, and cell adhesion and growth on the MBA-crosslinked gelatin was analyzed by OM after fixing with formalin and staining with toluidine blue. HUVEC were seeded onto ESF and ESF-coated samples and cultured under standard tissue culture conditions. After 7 days from seeding, cell proliferation was evaluated from the quantitation of total proteins in cell lysates (BCA protein assay) and the obtained results indicated a significantly higher (p < 0.05) cell growth on gelatin-coated ESF samples. Overall, these results point out that the described gelatin coating allows for the production of a structure with adequate mechanical properties for cardio-vascular applications and biological characteristics even better than those of silk fibroin. Full article
Open AccessProceedings
An Economical and Environmental Alternative to Traditional Can Manufacturing Using a New Pre-Laminated Steel
Mater. Proc. 2020, 2(1), 21; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06841 - 02 Aug 2020
Viewed by 642
Abstract
Metal containers are the most commonly used packaging worldwide in both the food processing industry. Usually, the production processes involved in the canning industry include multi-step transformations that take large aluminum or steel coils and make them into two or three-piece cans. During [...] Read more.
Metal containers are the most commonly used packaging worldwide in both the food processing industry. Usually, the production processes involved in the canning industry include multi-step transformations that take large aluminum or steel coils and make them into two or three-piece cans. During this process, these parts are sprayed to obtain a better surface for the contents; however, this spray produces volatile organic compounds (VOC). This paper presents a new and environmentally friendly can manufacturing method, which uses a novel pre-laminated two-layer polymer steel. As experimentally proven, this innovative polymer-coated steel successfully withstands every manufacturing requirement. The specimens were tested in an ironing simulator, measuring roughness, and friction coefficients. The development of an upper bound ironing model, along with a supporting neural network, allows an insight into the design of new materials for can manufacturing. Full article
Open AccessProceedings
Synthesis and Characterizations of 2D Platinum Diselenide
Mater. Proc. 2020, 2(1), 22; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06815 - 07 May 2020
Viewed by 309
Abstract
Platinum diselenide (PtSe2), which belongs to the transition metals dichalcogenide (TMDCs) class of 2D materials, is characterized with a transition from semimetal to semiconductor with a thickness variation from bulk to monolayer and found in versatile applications especially in sensors and [...] Read more.
Platinum diselenide (PtSe2), which belongs to the transition metals dichalcogenide (TMDCs) class of 2D materials, is characterized with a transition from semimetal to semiconductor with a thickness variation from bulk to monolayer and found in versatile applications especially in sensors and mid-infrared detectors. In this study we report the large-scale synthesis of PtSe2 layers by thermally assisted selenization of pre-deposited platinum films in a horizontal quartz-tube Chemical Vapor Deposition (CVD) reactor. Raman spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) are used for characterization of the obtained 2D PtSe2. It is observed that the Raman spectra of PtSe2 show strong dependence on the thickness (Pt deposition time). XPS analysis was applied to examine the chemical compositions in order to assess the quality of the synthesized PtSe2 films. All the studied properties reveal great potential to obtain continuous layers with a controlled thickness and composition and further potential for integration in functional heterostructures for future nanoelectronic and optoelectronic devices. Full article
Open AccessProceedings
Preliminary Studies on HVOF Sprayed Coatings on Magnesium Alloys
Mater. Proc. 2020, 2(1), 23; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06847 - 15 May 2020
Viewed by 360
Abstract
In the field of the development of modern techniques, which improve and/or regenerate the component’s surface properties, High Velocity Oxygen Fuel (HVOF) spraying of carbides or metals and their alloys is a good alternative method to other conventional surface engineering ones, including magnesium [...] Read more.
In the field of the development of modern techniques, which improve and/or regenerate the component’s surface properties, High Velocity Oxygen Fuel (HVOF) spraying of carbides or metals and their alloys is a good alternative method to other conventional surface engineering ones, including magnesium foundry alloys. Coatings manufactured by thermal spraying are used to improve the durability and life time of machine parts, both the new and regenerated ones, by changing the surface layer properties. In this work the results of HVOF sprayed coatings deposited onto AZ31 magnesium alloy substrate are reported. The feeding material was composite powder Cr3C2–NiCr. The coatings were investigated in terms of their microstructure and selected mechanical properties. For structure examinations, microscopy studies (light and scanning ones) were used as well as phase composition analysis. In the case of mechanical properties, the wear resistance was determined also microhardness was measured. Full article
Open AccessAbstract
Wood Protective Coatings Prepared with Silanes Based on Fatty Acids
Mater. Proc. 2020, 2(1), 24; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06804 - 26 Apr 2020
Viewed by 244
Abstract
Wood is one of the most important materials in the construction industry. Because of its organic constitution, it is slowly destroyed by the long-term impacts of water, oxygen and light under atmospheric conditions and, hence, needs to be sufficiently protected. Appropriate protection of [...] Read more.
Wood is one of the most important materials in the construction industry. Because of its organic constitution, it is slowly destroyed by the long-term impacts of water, oxygen and light under atmospheric conditions and, hence, needs to be sufficiently protected. Appropriate protection of wood leads to it having longer life and, hence, a huge reduction in maintenance costs. There are several methods to protect wood, either by its chemical modification or by its surface treatment. Unfortunately, many of the wood preservatives that have been used so far are highly toxic to humans and, hence, much attention has been paid to the development of nontoxic materials/methods for the protection of wood. Recently, several reports have been published on the use of inorganic–organic hybrid coatings for the protection of wood substrates. The sol–gel process to generate hybrid coatings is quite versatile and even allows room temperature deposition of hybrid inorganic–organic films on a wide range of substrates, including wood. Wood surface modification with multifunctional alkoxysilanes by the sol–gel process is one promising method to improve and provide new properties for wood materials. The advantage of the sol–gel process is that it allows deposition of a thin inorganic–organic layer on various substrates as a result of controlled hydrolysis and polycondensation of alkoxysilanes. The sol–gel coatings created on the wood surface provide barrier properties, moisture control and repellency properties. In this communication we present new trialkoxysilanes synthesised from fatty acid derivatives and their application in wood protective coatings. Full article
Open AccessProceedings
Resistance to Cavitation Erosion and the Sliding Wear of MCrAlY and NiCrMo Metallic Coatings
Mater. Proc. 2020, 2(1), 25; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06846 - 15 May 2020
Viewed by 346
Abstract
Bulk cobalt- and nickel-based metallic materials exhibit superior resistance to cavitation erosion and sliding wear. Thus, thermally deposited High-Velocity Oxygen Fuel (HVOF) coatings seem promising for increasing the wear resistance of the bulk metal substrate. However, the effect of chemical composition on the [...] Read more.
Bulk cobalt- and nickel-based metallic materials exhibit superior resistance to cavitation erosion and sliding wear. Thus, thermally deposited High-Velocity Oxygen Fuel (HVOF) coatings seem promising for increasing the wear resistance of the bulk metal substrate. However, the effect of chemical composition on the cavitation erosion and sliding wear resistance of M(Co,Ni)CrAlY and NiCrMo coatings has not yet been exhaustively studied. In this study, High-Velocity Oxygen Fuel (HVOF) coatings such as CoNiCrAlY, NiCoCrAlY, and NiCrMoFeCo were deposited on AISI 310 (X15CrNi25-20) steel coupons. The microstructure, hardness, phase composition and surface morphology of the as-sprayed coatings were examined. Cavitation erosion tests were conducted using the vibratory method in accordance with the ASTM G32 standard. Sliding wear was examined with the use of a ball-on-disc tribometer, and friction coefficients were measured. The mechanism of wear was identified with the scanning electron microscope equipped with an energy dispersive spectroscopy (SEM-EDS) method. In comparison to the NiCrMoFeCo coating, the CoNiCrAlY and NiCoCrAlY coatings have a lower sliding and cavitation wear resistance. Full article
Open AccessProceedings
Electrodeposited White Bronzes: A Comparison between Zn-Bearing and Zn-Free Coatings
Mater. Proc. 2020, 2(1), 26; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06824 - 13 May 2020
Viewed by 265
Abstract
White bronzes are ternary alloys composed of Cu, Zn and Sn, named after their bright whitish color. This class of alloys shares excellent hardness, corrosion and tarnishing resistance, and is commonly adopted in galvanic industrial processes as technological grade coatings to obtain layers [...] Read more.
White bronzes are ternary alloys composed of Cu, Zn and Sn, named after their bright whitish color. This class of alloys shares excellent hardness, corrosion and tarnishing resistance, and is commonly adopted in galvanic industrial processes as technological grade coatings to obtain layers with particular aesthetical and/or anticorrosive properties. Despite the widespread employment of white bronzes in fashion and the electronics industry, the recent literature lacks a characterization of these electrodeposited alloys with respect to more common binary (Cu-Sn) white bronzes. In this presentation, a thorough characterization of a commercial ternary Cu-Zn-Sn white bronze, produced by electrodeposition, is reported. Structural, chemical and physical characteristics of the deposited coating were investigated by various techniques (e.g., FIB/SEM, XPS, XRD, EDX, micro-hardness, color and corrosion tests). Results were compared with a similar set of measures obtained from a binary electrodeposited Cu-Sn white bronze (with a high tin content), in order to shed some light on the influence of Zn in the coating properties. Full article
Open AccessProceedings
Surface X-ray Diffraction Study of a Bi-Layer Junction Based on Cu and Cd Sulfides for Photovoltaic Applications
Mater. Proc. 2020, 2(1), 27; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06836 - 14 May 2020
Viewed by 268
Abstract
The development of new-generation photovoltaic devices through more sustainable production techniques and materials is driven by the need to contain the threats to the biosphere while guaranteeing the safety of the supply, accounting for the limited availability of fossil fuels. This study investigates [...] Read more.
The development of new-generation photovoltaic devices through more sustainable production techniques and materials is driven by the need to contain the threats to the biosphere while guaranteeing the safety of the supply, accounting for the limited availability of fossil fuels. This study investigates the crystal structure of thin films of chalcogenides, particularly a junction with a p-type (Cu2S) and an n-type (CdS) layer deposited one on top of the other on a Ag(111) substrate, starting from an aqueous solution and by means of electrochemical atomic layer deposition (E-ALD) (the system is denoted by (Cu2S)60/(CdS)60/Ag(111)). The experiment highlights the profound epitaxial relationship existing between the films and the bulk, consequent to the homogenization of the metrics of the CdS and the Cu2S structures to values commensurate to the surface periodicity of the substrate. Cadmium sulfide develops an elementary cell with crystallographic axes parallel to those of the Ag(111) and parameters |a|, |b| and |c| not found in any of the known mineral phases. The comparison with the wurtzite-type structure of greenockite shows a compensation mechanism related to the strain imposed by the film growth on the crystallographic Ag(111) surface. The positions in the reciprocal space of the Cu2S reflection is compatible with a pseudo-hexagonal pattern rotated by 30° with respect to the Ag, as already noticed in relation to a Cu2S/Ag(111) E-ALD deposit (Giaccherini et al., 2017). The Cu2S c axis results parallel to the direction [111] of the Ag substrate and its structure is characterized by the strong occurrence of the 3.963 Å periodicity, which corresponds to the interatomic distance S-S in the triangular CuS3 groups, the basis of all the mineral Cu2-xS group structures. These data suggest a pseudo-hexagonal chalcocite-like structure with a planarization of S layers (Giaccherini et al., 2017) as a result of the strong epitaxial relationship existing with the CdS below. This study confirms E-ALD as an energy efficient method for the growth of semiconducting heterostructures with tailored properties. Full article
Open AccessProceedings
The Influence of CrAlN Coating Chemical Composition on Soldering Resistance in Contact with Al-Si-Cu Alloy
Mater. Proc. 2020, 2(1), 28; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06837 - 14 May 2020
Viewed by 258
Abstract
During the high pressure die casting (HPDC) process the die material is exposed to thermal fatigue, erosion, and corrosion. Corrosion leads to the soldering of cast alloy to tool surfaces which consequently bonds the casting with die material. Besides wear, such a process [...] Read more.
During the high pressure die casting (HPDC) process the die material is exposed to thermal fatigue, erosion, and corrosion. Corrosion leads to the soldering of cast alloy to tool surfaces which consequently bonds the casting with die material. Besides wear, such a process reduces the casting quality and production efficiency and endangers the tool integrity. Application of thin ceramic coatings on die surfaces reduces the soldering effects and improves the die performance. However, the development of ceramic coatings for these purposes still requires detailed information on the phenomena involved in these processes. In this study, the soldering performance of a complex nanolayer CrAlN coating, with three chemical compositions (high-Cr, balanced Cr:Al, and high-Al content) were evaluated. The cast alloy soldering was evaluated by the detachment test in three configurations. In this test, a simple casting is formed in contact with flat coated surfaces. Upon casting solidification, the formed joint is dismantled, and a force required for this process was recorded. To characterize and quantify the exhibited wear, after the detachment test, surfaces of the coated samples were analyzed by different microscopy techniques. Two forms of wear were detected on investigated samples. Cast alloy soldering processes induced the formation of thin layers of cast alloy on the surfaces of all investigated coatings. Additionally, substrate corrosion through the coating growth defects caused coating layer delamination during the detachment test. The evaluated coatings displayed different behaviors regarding the extent of wear and values of the detachment force. The coating with a balanced CrAlN composition exhibited the best soldering and corrosion resistance and displayed the lowest ejection force. In terms of soldering and corrosion resistance, the high-Al coating outperformed the high-Cr content coating. However, high-Al and high-Cr coating exhibited significantly higher and quite comparable values of detachment force. Based on the quantitative results it was postulated that, besides soldering and substrate corrosion, the casting-coating bonding strength depends also on “pure” sticking effects of cast alloy to coated surfaces. Full article
Open AccessProceedings
Natural Rubber Composites for Paper Coating Applications
Mater. Proc. 2020, 2(1), 29; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06832 - 13 May 2020
Viewed by 252
Abstract
Natural rubbers are characterized by extremely high molecular weight that might be beneficial in the formation of a protective barrier layer on paper substrates, providing good cohesive properties but limited adhesion to the substrate. In parallel, the low glass transition temperature of natural [...] Read more.
Natural rubbers are characterized by extremely high molecular weight that might be beneficial in the formation of a protective barrier layer on paper substrates, providing good cohesive properties but limited adhesion to the substrate. In parallel, the low glass transition temperature of natural rubber might give the opportunity for good sealability, in contrast with severe problems of tack. Therefore, natural rubbers can be good candidates to serve as an alternative ecological binder in paper coatings for water and grease barrier resistance. In order to tune the surface properties of the paper coating, the effect of different fillers in natural rubber coatings are evaluated on rheological, thermo–mechanical and surface properties. The fillers are selected according to common practice for the paper industry, including talc, kaolinite clay and a type of organic nanoparticle, which are all added in the range of 5 to 20 wt.-%. Depending on the selected natural rubber, the dispersibility range (i.e., dispersive and distributive mixing) of the fillers in the latex phase highly varies and filler/matrix interactions are the strongest for nanoparticle fillers. An optimum selection of viscosity range allows us to obtain homogeneous mixtures without the need of surface modification of the additives. After bar-coating natural rubber latex composites on paper substrates, the drying properties of the composite coatings are followed by spectroscopy, illustrating the influences of selected additives on the vulcanization process. In particular, the latter most efficiently improves in the presence of nanoparticle fillers and highly increases the coating hydrophobicity in parallel, reducing the adhesive tack surface properties, as predicted from calculated work of adhesion. Full article
Open AccessProceedings
Properties of Thin Film-Covered GaN(0001) Surfaces
Mater. Proc. 2020, 2(1), 30; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06833 - 13 May 2020
Viewed by 313
Abstract
In this paper, the surface properties of bare and film-covered gallium nitride (GaN) of the wurtzite form, (0001) oriented are summarized. Thin films of several elements—manganese, nickel, arsenic and antimony—are formed by the physical vapour deposition method. The results of the bare surfaces [...] Read more.
In this paper, the surface properties of bare and film-covered gallium nitride (GaN) of the wurtzite form, (0001) oriented are summarized. Thin films of several elements—manganese, nickel, arsenic and antimony—are formed by the physical vapour deposition method. The results of the bare surfaces as well as the thin film/GaN(0001) phase boundaries presented are characterized by X-ray and ultraviolet photoelectron spectroscopies (XPS, UPS). Basic information about electronic properties of GaN(0001) surfaces are shown. Different behaviours of thin films after post-deposition annealing in ultrahigh vacuum conditions, such as surface alloying, subsurface dissolving and desorbing, are found. The metal films form surface alloys with gallium (NiGa, MnGa), while the semi-metal (As, Sb) layers easily evaporate from the GaN(0001) surface. However, the layer in direct contact with the substrate can react with it modifying the surface properties of GaN(0001). Full article
Open AccessProceedings
Compression Molding of Polyhydroxybutyrate Nano-Composite Films as Coating on Paper Substrates
Mater. Proc. 2020, 2(1), 31; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06797 - 20 Apr 2020
Viewed by 216
Abstract
After successful preparation of master batch formulations including polyhydroxybutyrate (PHB) and fibrillated cellulose, the compositions of PHB with different types and concentrations of fillers were used for the deposition of a coating on packaging paper grades, by using compression molding technique in a [...] Read more.
After successful preparation of master batch formulations including polyhydroxybutyrate (PHB) and fibrillated cellulose, the compositions of PHB with different types and concentrations of fillers were used for the deposition of a coating on packaging paper grades, by using compression molding technique in a hydraulic press. The resulting paper coatings are demonstrated to provide a green solution for the production of protective barrier layer films with tunable hydrophobicity and oxygen barrier resistance. The processing of the nanocomposites into flat and homogeneous coatings was optimized for different conditions of molding temperature and times, in particular, the flow conditions of the coating under pressing in contact with the paper substrate strongly depends on the presence of fillers. The effects of filler types on adhesion of the coating at the paper/polymer interface were investigated and the poor adhesion of native PHB coatings was improved after hydrophobic surface modification of the nanocellulose fillers. Under compression molding, the unique inclusion styrene-maleimide nanoparticles with encapsulated wax attached to the nanocellulose fiber surface enhanced the flowing properties of the coating by eliminating fiber agglomeration in contact with the paper substrate and reducing the effects of fiber pull outs. Therefore, hydrophobic fiber modification and the role of wax as a lubricant is necessary to obtain a homogenous dispersion during compressing molding of coating materials for papers. Full article
Open AccessProceedings
Surface Topography and Grain Morphology of Nanolayer TiAlN/TiSIN Coating Governed by Substrate Material and Rotation during Deposition
Mater. Proc. 2020, 2(1), 32; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06822 - 12 May 2020
Viewed by 187
Abstract
Nanolayer TiAlN/TiSiN coating is one of the most advanced contemporary protective coatings. It has been applied for protection of machining tools, forming tools, and die casting tools. However, due to its versatile properties, there is a high potential for broadening its application; for [...] Read more.
Nanolayer TiAlN/TiSiN coating is one of the most advanced contemporary protective coatings. It has been applied for protection of machining tools, forming tools, and die casting tools. However, due to its versatile properties, there is a high potential for broadening its application; for example, for protection of biomedical implants. Each application requires specific base materials, for example cold working steels are used for forming, while stainless steels are applied for biomedical purposes. Different materials and their pre-treatment might result in different coating properties even if coating was conducted in a single batch. Real tools and components have complex geometries, and as such require a multiple-axis rotation during the deposition. Among other properties, grain morphology and surface topography are of great importance in a real application. Since systematic studies on the effect of substrate materials and rotation during deposition on these properties are very scarce, in this article we studied TiAlN/TiSiN coating magnetron sputtered on five different substrates, prepared with 1-, 2-, and 3-fold rotations. Cold-work tool steel (X153CrMoV12), hot-work tool steel (X37CrMoV5-1), plasma-nitrided hot-work tool steel, surgical stainless steel (X2CrNiMo18-15-3), and cemented carbide (WC/Co) were used as substrate materials. Three-dimensional stylus profilometry and atomic force microscopy were used for evaluation of micro and nano topography. The coated surgical steel has the highest roughness (Sa) which corresponds to the highest number of coating growth defects. However, the size of the individual growth defects was considerably smaller for this substrate than for other substrate materials. The observed difference is linked to differences in the concentration of specific carbides contained in a specific steel. Since different carbides have different polishing and ion-etching rates, coatings on different steels may have different concertation of defects. Columnar grain analysis revealed that coating on surgical steel exhibited the smallest column diameter (125 nm) and their highest uniformity. Column diameter on other substrates is around 215 nm, while hot-working tool steel exhibited the largest columns (235 nm). Such findings suggest that the same coating may exhibit different mechanical properties on different substrates. Coatings produced with the higher degree of rotation (2-fold, 3-fold) have fewer defects and a smoother surface. There was no clear trend between columnar grain size and the number of rotational degrees. Full article
Open AccessProceedings
Novel Catalysts for Selective Catalytic Reduction of NOx by NH3 Prepared by Atomic Layer Deposition of V and Ti Oxides on SiO2 Powder
Mater. Proc. 2020, 2(1), 33; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06814 - 07 May 2020
Viewed by 208
Abstract
Based on the 2019 report of the European Environment Agency on Air Quality in Europe nitrogen oxides (NOx) were identified as the most harmful air pollutants in terms of damage to ecosystems. Moreover, in Europe, NO2 is pinpointed as one [...] Read more.
Based on the 2019 report of the European Environment Agency on Air Quality in Europe nitrogen oxides (NOx) were identified as the most harmful air pollutants in terms of damage to ecosystems. Moreover, in Europe, NO2 is pinpointed as one of the most dangerous pollutants for human health. Anthropogenic emissions of NOx are mainly generated by the combustion of fossil fuels. Nitrogen oxides being emitted into the atmosphere cause environmental problems such as acid rain, acidification of soil, lakes and rivers, eutrophication and photochemical smog. The most effective and widely applicable technology to date for the purification of flue gases from NOx is selective catalytic reduction using ammonia (NH3-SCR de-NOx). Nowadays, one of the most significant research fields in NH3-SCR de-NOx is the application of unconventional reduction methods and the preparation of novel catalysts possessing high specific surface area, uniformity, dispersion of active sites, activity and selectivity. Atomic layer deposition (ALD) is an attractive technique for the deposition of uniformly distributed active catalytic layers, or nanoparticles, on highly porous substrates characterized by a complex structure. For this type of materials, conventional catalyst preparation methods (e.g., impregnation or deposition precipitation) can encounter several limitations. The significant advantage of ALD for the preparation of supported catalysts is that the process can be controlled on the atomic scale, providing the required thickness of an active layer, synthesized with a sub-nm accuracy. Moreover, ALD ensures the formation of catalytic sites from the gas phase, which enhances the possibility of active species being deposited inside pores which are very small in size. In this study, ALD was applied to the preparation of VxOy-based NH3-SCR de-NOx catalysts. Highly porous silica gel powder (63–100 μm) with a specific surface area of up to 450 m2·g1 was used as a substrate for VxOy/SiO2 with different metal loadings (wt.%). In addition (VxOy+TiO2)/SiO2 catalysts were prepared by applying vanadium (V) tri-i-propoxy oxide (VTIP) and titanium tetrachloride (TiCl4) as precursors with deionized water as the co-reactant. Elemental analysis (ICP-OES) revealed that vanadium loadings of the VxOy/SiO2 catalysts were 0.3, 0.7, 1.1 and 1.60 wt.%, while the loadings in the TiO2-promoted VxOy/SiO2 catalyst were 1.0 and 0.2 wt.% for V and Ti, respectively. The obtained XPS spectra indicated the presence of V2O3 and V2O5 species (V2O5/V2O3 ratio was 1.6 and 6.3 for the as-synthesized and calcined samples respectively). Vanadium(V) oxide is known to be a catalytically active compound for NH3-SCR de-NOx. Additionally, TEM, XRD and N2 adsorption (BET) analyses were conducted to provide a comprehensive characterization of the species size, crystalline phase and porosity of the catalysts prepared. Full article
Open AccessProceedings
Characterization of Electrochemical Sensors Based on Carbon Nanotubes and MIPS for Determination of Ferulic Acid
Mater. Proc. 2020, 2(1), 34; https://0-doi-org.brum.beds.ac.uk/10.3390/CIWC2020-06838 - 14 May 2020
Viewed by 286
Abstract
In order to mitigate the impacts caused by the rampant consumption of fossil fuels, many countries are investing in the development and optimization of alternatives that minimize dependence on fossil energy. The second generation of ethanol (2G), characterized by its relevant production potential, [...] Read more.
In order to mitigate the impacts caused by the rampant consumption of fossil fuels, many countries are investing in the development and optimization of alternatives that minimize dependence on fossil energy. The second generation of ethanol (2G), characterized by its relevant production potential, is considered a good alternative, which can be produced from sugarcane bagasse. Therefore, it is extremely important to evaluate the efficiency of 2G ethanol production processes, mainly in the compositional analysis of hydrolysates from the pre-treatment of lignocellulosic biomass, to promote greater production. Thus, the development of electrochemical sensors composed of graphite/paraffin composite electrodes coated with multi-walled carbon nanotubes (MWCNTs) modified with molecularly imprinted polymers (MIPs) are an excellent option for carrying out rapid analyzes. Due to the highly sensitive electrical properties of the MWCNTs and the molecular impression of the polymers that allow a high affinity with the model molecule, the sensor has high selectivity, good sensitivity and reproducibility for the determination of ferulic acid. For this reason, the present work, using the Scanning Electron Microscopy (SEM) and Cyclic Voltammetry (CV) technique, presents remarkable morphological characteristics of the sensor surface and its electrochemical behavior in relation to the electropolymerization process and speed increase of the scan. Full article
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