Search results for: coating compositions

Authors: Yoko Suganuma Oi

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The purpose of the present study is to find the efficacy of high school student self-assessment of written production. It aimed to explore the following two research questions: 1)How is topic development of their written production improved after student self-assessment and teacher feedback? 2)Does the consistency between student self-assessment and teacher assessment develop after student self-assessment and teacher feedback? The data came from the written production of 82 Japanese high school students aged from 16 to 18 years old, an American English teacher and one Japanese English teacher. Students were asked to write English compositions, about 150 words, for thirty minutes without using dictionaries. It was conducted twice at intervals of two months. Students were supposed to assess their own compositions by themselves. Teachers also assessed students’ compositions using the same assessment sheet. The results showed that both teachers and students assessed the second compositions higher than the first compositions. However, there was not the development of the consistency in coherence.

Keywords: feedback, self-assessment, topic development, high school students

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Authors: Nazanin Sheibanian, Raffaella Sesana, Sedat Ozbilen

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In recent years, high-entropy alloys (HEAs) have attracted considerable attention due to their unique properties and potential applications. In this study, novel HEA coatings were prepared on Mg substrates using mechanically alloyed HEA powder feedstocks based on Al_(0.1-0.5)CoCrCuFeNi and MnCoCrCuFeNi multi-material systems. The coatings were deposited by the Cold Spray (CS) process using three different temperatures of the process gas (N2) (650°C, 750°C, and 850°C) to examine the effect of gas temperature on coating properties. In this study, Infrared Thermography (non-destructive) was examined as a possible quality control technique for HEA coatings applied to magnesium substrates. Active Thermography was employed to characterize coating properties using the thermal response of the coating. Various HEA chemical compositions and deposition temperatures have been investigated. As a part of this study, a comprehensive macro and microstructural analysis of Cold Spray (CS) HEA coatings has been conducted using macrophotography, optical microscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM+EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), microhardness tests, roughness measurements, and porosity assessments. These analyses provided insight into phase identification, microstructure characterization, deposition, particle deformation behavior, bonding mechanisms, and identifying a possible relationship between physical properties and thermal responses. Based on the figures and tables, it is evident that the Maximum Relative Radiance (∆RMax) of each sample differs depending on both the chemical composition of HEA and the temperature at which Cold Spray is applied.

Keywords: active thermography, coating, cold spray, high- entropy alloy, material characterization

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Authors: J. Suwanprateeb, F. Thammarakcharoen

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Calcium phosphate coating (CaP) has been employed for protein delivery, but the typical direct protein adsorption on the coating led to low incorporation content and fast release of the protein from the coating. By using bovine serum albumin (BSA) as a model protein, rapid biomimetic co-precipitation between calcium phosphate and BSA was employed to control the distribution of BSA within calcium phosphate coating during biomimetic formation on titanium surface for only 6 h at 50 oC in an accelerated calcium phosphate solution. As a result, the amount of BSA incorporation and release duration could be increased by using a rapid biomimetic co-precipitation technique. Up to 43 fold increases in the BSA incorporation content and the increase from 6 h to more than 360 h in release duration compared to typical direct adsorption technique were observed depending on the initial BSA concentration used during co-precipitation (1, 10, and 100 microgram/ml). From X-ray diffraction and Fourier transform infrared spectroscopy studies, the coating composition was not altered with the incorporation of BSA by this rapid biomimetic co-precipitation and mainly comprised octacalcium phosphate and hydroxyapatite. However, the microstructure of calcium phosphate crystals changed from straight, plate-like units to curved, plate-like units with increasing BSA content.

Keywords: biomimetic, Calcium Phosphate Coating, protein, titanium

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Authors: Ferhat Bülbül

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The use of magnesium alloys is limited due to their susceptibility to corrosion although they have many attractive physical and mechanical properties. To increase mechanical and corrosion properties of these alloys, many deposition method and coating types are used. Electroless Ni–B coatings have received considerable interest recently due to its unique properties such as cost-effectiveness, thickness uniformity, good wear resistance, lubricity, good ductility and corrosion resistance, excellent solderability and electrical properties and antibacterial property. In this study, electroless Ni-B coating could been deposited on AZ91 magnesium alloy. The obtained coating exhibited an amorphous and rougher structure.

Keywords: magnesium, electroless Ni–B, X-ray diffraction, amorphous

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Authors: Nouby Ghazaly, Gamal Fouad, Ali Abd-El-Tawwab, K. A. Abd El-Gwwad

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The purpose of this paper is to examine the piston stress distribution using several thicknesses of the coating materials to achieve higher gasoline engine performance. First of all, finite element structure analysis is used to uncoated petrol piston made of aluminum alloy. Then, steel and cast-iron piston materials are conducted and compared with the aluminum piston. After that, investigation of four coating materials namely, yttria-stabilized zirconia, magnesia-stabilized zirconia, alumina, and mullite are studied for each piston materials. Next, influence of various thickness coating layers on the structure stresses of the top surfaces is examined. Comparison between simulated results for aluminum, steel, and cast-iron materials is reported. Moreover, the influences of different coating thickness on the Von Mises stresses of four coating materials are investigated. From the simulation results, it can report that the maximum Von Mises stresses and deformations for the piston materials are decreasing with increasing the coating thickness for magnesia-stabilized zirconia, yttria-stabilized zirconia, mullite and alumina coated materials.

Keywords: structure analysis, aluminum piston, MgZrO₃, YTZ, mullite and alumina

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Authors: Charizza D. Montarin, Daryl Jae S. Sigue, Gilford Estores

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Philippines was moderately vulnerable to corrosion and to prevent this problem, surface coating should be applied. The main objective of this research was to develop and optimize a bio-based mixture of Pili Resin and Lime as Coating Materials. There are three (3) factors to be considered in choosing the best coating material such as chemical adhesion, friction, and the bearing/shear against the steel bar-concrete interface. Fortunately, both proportions of the Bio-based coating materials (50:50 and 65:35) do not have red rust formation complying with ASTM B117 but failed in terms of ASTM D 3359. Splitting failures of concrete were observed in the Unconfined Reinforced Concrete Samples. All of the steel bars (uncoated and coated) surpassed the Minimum Bond strength (NSCP 2015) about 203% to 285%. The experiments were about 1% to 3% of the results from the ANSYS Simulations with and without Salt Spray Test. Using the bio-based and epoxy coatings, normal splitting strengths were declined. However, there has no significant difference between the results. Thus, the bio-based coating materials can be used as an alternative for the epoxy coating materials and it was highly recommended for Low – Rise Building only.

Keywords: Canarium luzonicum, calcium oxide, corrosion, finite element simulations

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Authors: A. Mohammed, R. Lewis, M. Marshall

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Commonly used coatings to protect tools in die casting were used. A heat treatment and then surface coating can have a large effect on erosion damage. Samples have been tested to evaluate their resistances to erosive wear and to assess how this compares with behaviour seen for untreated material. Five commercial (PN + TiN), (PN + TiAlCN), (TiN X 2), (TiN), and (TiAlCN) coatings have been evaluated for their wear resistance. The objective was to permit an optimized selection of coatings to be used to give good resistance to erosive wear. A test-Rig has been developed to study the erosive wear in aluminium die casting and provide an environment similar to industrial operation that is more practical than using actual machines. These surfaces were analysed using a Scanning Electron Microscope (SEM) and Optical Microscopes each with a different level of resolution. Examination of coating materials revealed an important parameter associated with the failure of the coating materials.This was adhesion of the coating material to the substrate surface. A well-adhered coating withstands wear much better compared to the poorest-adhering coating.

Keywords: solid particle erosion, PVD-coatings, steel, erosion testing

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Authors: Xiping Guo, Jing Li

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The microstructure of an Si-Al-Y co-deposition coating prepared on an Nb-Si based ultra high temperature alloy by pack cementation process at 1250°C for eight hours was studied. The results showed that the coating was composed of a (Nb,X)Si₂ (X represents Ti, Cr and Hf elements) outer layer, a (Ti,Nb)₅Si₄ middle layer and an Al, Cr-rich inner layer. For comparison, the oxidation behaviors of the coating at 800, 1050 and 1350°C were investigated respectively. Linear oxidation kinetics was found with the parabolic rate constants of 5.29×10⁻², 9×10⁻²and 5.81 mg² cm⁻⁴ h⁻¹, respectively. Catastrophic pesting oxidation has not been found at 800°C even for 100 h. The surface of the scale was covered by compact glassy SiO₂ film. The coating was able to effectively protect the Nb-Si based alloy from oxidation at 1350°C for at least 100 h. The formation process of the scale was testified following an epitaxial growth mechanism. The mechanism responsible for the oxidation behavior of the Si-Al-Y co-deposition coating at 800, 1050 and 1350°C was proposed.

Keywords: Nb-Si based ultra high temperature alloy, oxidation resistance, pack cementation, silicide coating, Al and Y modified

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Authors: D. Zujur, J. Moret, D. Rodriguez, L. Cruz, J. Lira, L. Gil, E. Dominguez, J. F. Alvarez-Barreto

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In this work, chitosan (CH) has been used to produce a novel coating for Ti6Al4V, the most widely used alloy in orthopedic implants, so as to improve the biological tissue response at the metallic surface. The Ti6Al4V surface was sandblasted with alumina particles and observed by SEM. Chitosan was chemically modified, via crodiimide chemistry, with lactobionic and 4-azidebenzoic acid to make it soluble at physiological pH and photo-crosslinkable, respectively. The reaction was verified by FTIR, NMR, and UV/vis spectroscopy. Ti6Al4V surfaces were coated with solutions of the modified CH and exposed to UV light, causing the polymer crosslinking, and formation of a hydrogel on the surface. The crosslinking reaction was monitored by FTIR at different exposure times. Coating morphology was observed by SEM. The coating´s cytocompatibility was determined in vitro through the culture of rat bone marrow´s mesenchymal stem cells, using an MTT assay. The results show that the developed coating is cytocompatible, easy to apply and could be used for further studies in the encapsulation of bioactive molecules to improve osteogenic potential at the tissue-implant interface.

Keywords: chitosan, photo-crosslinking, Ti6Al4V, bioactive coating, hydrogel

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Authors: O. Dvorak, M. Panek, E. Oberhofnerova, I. Sterbova

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Extractives contained in larch wood (Larix decidua, Mill.) reduce the service-life of exterior coating systems, especially transparent and semi-transparent. The aim of this work was to find out whether the initial several-week leaching of extractives from untreated wood in the exterior will positively affect the selected characteristics and the overall life of the semi-transparent oil-based coating. Samples exposed to exterior leaching for 10 or 20 weeks, and the reference samples without leaching were then treated with a coating system. Testing was performed by the method of artificial accelerated weathering in the UV chamber combined with thermal cycling during 6 weeks. The changes of colour, gloss, surface wetting, microscopic analyses of surfaces, and visual damage of paint were evaluated. Only 20-week initial leaching had a positive effect. Both to increase the color stability during aging, but also to slightly increase the overall life of the tested semi-transparent coating system on larch wood.

Keywords: larch wood, coating, durability. extractives

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Authors: M. J. Suriani, F. Mansor, W. Siti Maizurah, I. Nurizwani

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Silicon Carbide (SiC) is one of the Silicon-based materials, which get interested by the researcher. SiC is an emerging semiconductor material, which has received a great deal of attention due to their application in high frequency and high power systems. Although its superior characteristic for a semiconductor material, its outstanding mechanical properties, chemical inertness and thermal stability has gained important aspect for a surface coating for deployment in extreme environments. Very high frequency (VHF)-PECVD technique utilized to deposit nano ns-SiC film in which variation in chamber pressure, substrate temperature, RF power and precursor gases flow rate will be investigated in order to get a good quality of thin film coating. Characterization of the coating performed in order to study the surface morphology, structural information. This performance of coating evaluated through corrosion test to determine the effectiveness of the coating for corrosion prevention. Ns-SiC film expected to possess better corrosion resistance and optical properties, as well as preserving the metal from the marine environment. Through this research project, corrosion protection performance by applying coating will be explored to obtain a great corrosion prevention method to the shipping and oil and gas industry in Malaysia. Besides, the cost of repair and maintenance spending by the government of Malaysia can be reduced through practicing this method.

Keywords: composite materials, marine corrosion, nano-composite, nano structure–coating

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Authors: Xiao-Li Liu, Ling-Yun Zhao, Xing-Jie Liang, Hai-Ming Fan

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Owing to their unique properties, magnetic nanoparticles have been used as diagnostic and therapeutic agents for biomedical applications. Highly monodispersed magnetic nanoparticles with controlled particle size and surface coating have been successfully synthesized as a model system to investigate the effect of surface coating on the T2 relaxivity and specific absorption rate (SAR) under an alternating magnetic field, respectively. Amongst, by using mPEG-g-PEI to solubilize oleic-acid capped 6 nm magnetic nanoparticles, the T2 relaxivity could be significantly increased by up to 4-fold as compared to PEG coated nanoparticles. Moreover, it largely enhances the cell uptake with a T2 relaxivity of 92.6 mM-1s-1 for in vitro cell MRI. As for hyperthermia agent, SAR value increase with the decreased thickness of PEG surface coating. By elaborate optimization of surface coating and particle size, a significant increase of SAR (up to 74%) could be achieved with a minimal variation on the saturation magnetization (<5%). The 19 nm magnetic nanoparticles with 2000 Da PEG exhibited the highest SAR of 930 W•g-1 among the samples, which can be maintained in various simulated physiological conditions. This systematic work provides a general strategy for the optimization of surface coating of magnetic core for high performance MRI contrast agent and hyperthermia agent.

Keywords: magnetic nanoparticles, magnetic hyperthermia, magnetic resonance imaging, surface modification

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Authors: Sergey M. Karabanov, Dmitry V. Suvorov

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Magnetically controlled microelectromechanical system (MCMEMS) switches is one of the directions in the field of micropower switching technology. MCMEMS switches are a promising alternative to Hall sensors and reed switches. The most important parameter for MCMEMS is the contact resistance, which should have a minimum value and is to be stable for the entire duration of service life. The value and stability of the contact resistance is mainly determined by the contact coating material. This paper presents the research results of a contact coating based on nanoscale ruthenium films obtained by electrolytic deposition. As a result of the performed investigations, the deposition modes of ruthenium films are chosen, the regularities of the contact resistance change depending on the number of contact switching, and the coating roughness are established. It is shown that changing the coating roughness makes it possible to minimize the contact resistance.

Keywords: contact resistance, electrode coating, electrolytic deposition, magnetically controlled MEMS

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Authors: Szymon Kugler, Krzysztof Kowalczyk, Tadeusz Spychaj

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An addition of carbon nanotubes (CNT) can simultaneously improve many features of epoxy coatings, i.e. electrical, mechanical, functional and thermal. Unfortunately, this nanofiller negatively affects visual properties of the coatings, such as transparency and gloss. The main reason for the low visual performance of CNT-modified epoxy coatings is the lack of compatibility between CNT and popular amine curing agents, although epoxy resins based on bisphenol A are indisputable good CNT dispersants. This is a serious obstacle in utilization of the coatings in advanced applications, demanding both high transparency and electrical conductivity. The aim of performed investigations was to find amine curing agents exhibiting affinity for CNT, and ensuring good performance of epoxy coatings with them. Commercially available CNT was dispersed in epoxy resin, as well as in different aliphatic, cycloaliphatic and aromatic amines, using one of two dispergation methods: ultrasonic or mechanical. The CNT dispersions were subsequently used in the preparation of epoxy coating compositions and coatings on a transparent substrate. It was found that amine derivative of bio-based cardanol, as well as modified o-tolylbiguanide exhibit significant CNT, dispersing properties, resulting in improved transparent/electroconductive performance of epoxy coatings. In one of prepared coating systems just 0.025 wt.% (250 ppm) of CNT was enough to obtain coatings with semi conductive properties, 83% of transparency as well as perfect chemical resistance to methyl-ethyl ketone and improved thermal stability. Additionally, a theory of the influence of amine chemical structure on CNT dispersing properties was proposed.

Keywords: bio-based cardanol, carbon nanotubes, epoxy coatings, tolylbiguanide

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Authors: D. Abid, A. Guettar, A. Toubane, A. Bouda, K. Daoud

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The aim of this work is to study coating formulations rheology. Fourteen solutions were prepared with Hydroxypropyl methylcellulose (HPMC) percentage which varies from 2 to 20 %, Ethyl cellulose (EC) percentage varying from 1 to 3 % and Titanium dioxide (TiO2) percentage which vary from 1 to 3%, Opadry solution (25%) was used as a reference for this study. Two behaviors appeared obviously ‘pseudo plastic’ and ‘dilatant’ related to the percentage of HPMC, this allowed us to define that HPMC is the polymer which influence the behavior of coating solutions.

Keywords: rheology, opadry, HPMC, B1-B6 tablets

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Authors: Sukru Dursun, Zeynep Cansu Ayturan, Mostafa Maroof

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Metal coating which is important method used for protecting metals against oxidation and corrosion, decreasing friction, protecting metals from chemicals, easing cleaning of the metals. There are several methods used for metal coating such as hot-dip galvanizing, thermal spraying, electroplating and sherardizing. Method which will be used for metal coating depends on the type of metal. The materials mostly used for coating are zinc, nickel, brass, chrome, gold, cadmium, copper, brass, and silver. Within these materials, chrome ion has significant negative impacts on human, other living organisms and environment. Moreover, especially on human chrome may cause lung cancer, stomach ulcer, kidney and liver function disorders and death. Therefore, wastewaters of metal coating industry including chrome should be treated very carefully. In this study, wastewater containing chrome produced by metal coating industry was analysed with phytotoxicity method that is based on measuring the reaction of some plant species against different concentrations of chrome solution. Main plants used for phytotoxicity tests are Lepidium sativum and Lemna minor. Owing to phytotoxicity test, assessing the negative effects of chrome which may harm plants and offering more accurate wastewater treatment techniques against chromium wastewater is possible. Furthermore, the results taken from phytotoxicity tests were analysed with respect to their variance and their importance against different concentrations of chrome solution were determined.

Keywords: metal coating wastewater, chrome, phytotoxicity, Lepidium sativum, Lemna minor

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Authors: Young Jun Lee, Tae Hyuk Lee, Kyoung Tae Park, Jong Hyeon Lee

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The harsh atmosphere of the sulfur-iodine process used for producing hydrogen requires better corrosion resistance and mechanical properties that is possible to obtain with pure tantalum. Ta-W alloy is superior to pure tantalum but is difficult to alloy due to its high melting temperature. In this study, substrates of near-net shape (Swagelok® tube ISSG8UT4) were coated with Ta-W using the multi-anode reactive alloy coating (MARC) process in molten salt (LiF-NaF-K2TaF7) at different current densities (1, 2 and 4mA/cm2). Ta-4W coating films of uniform coating thicknesses, without any entrapped salt, were successfully deposited on Swagelok tube by electrodeposition at 1 mA/cm2. The resulting coated film with a corrosion rate of less than 0.011 mm/year was attained in hydriodic acid at 160°C, and hardness up to 12.9 % stronger than pure tantalum coated film. The alloy coating films also contributed to significant enhancement of corrosion resistance.

Keywords: tantalum, tantalum alloy, tungsten alloy, electroplating

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Authors: An Cheng, Hui-Mi Hsu, Sao-Jeng Chao, Wei-Ting Lin

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This study investigated the mechanical properties and durability of concrete produced using recycled fine aggregate (RFA) pre-coated with fly ash, slag, and a polymer solution (PVA). We investigated the physical and microscopic properties of fresh concrete while adjusting several of the fabrication parameters, such as the constituent makeup and thickness of RFA pre-coatings. The study is divided into two parts. The first part involves mortar testing in which the RFA used for coating had a water/cement ratio of 0.5 and fly ash, slag, and PVA viscosity of 5~6cps, 21~26cps, 25~30cps, or 44~50cps. In these tests, 100% of the natural fine aggregate was replaced by RCA. The second part of the study involved the mixing of concrete with 25% FRA, which was respectively coated with fly ash, slag, or PVA at a viscosity of 44~50cps. In these tests, the water/cement ratio was either .4 or 0.6. The major findings in this study are summarized as follows: Coating RFA coated with fly ash and PVA was shown to increase flow in the fresh concrete; however, the coating of FRA with slag resulted in a slight decrease in flow. Coating FRA with slag was shown to improve the compressive and splitting strength to a greater degree than that achieved by coating FRA with fly ash and PVA. The mechanical properties of concrete mixed with slag were shown to increase with the thickness of the coating. Coating FRA with slag was also shown to enhance the durability of the concrete, regardless of the water/cement ratio.

Keywords: recycled fine aggregates, pre-coated, fly ash, slag, pre-coated thickness

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Authors: D. Kari Basavaraja, M. G. Skanda, C. Soumya, V. Ramesh

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This paper discusses the effects of sodium hypophosphite concentration, pH, and temperature on deposition rate. This paper also discusses the evaluation of coating strength, surface, and subsurface by varying the bath parameters, percentage of phosphate, plating temperature, and pH of the plating solution. Taguchi technique has been used for the analysis. In the experiment, nickel chloride which is a source of nickel when mixed with sodium hypophosphite has been used as the reducing agent and the source of phosphate and sodium hydroxide has been used to vary the pH of the coating bath. The coated samples are tested for impact energy by conducting impact test. Finally, the effects of coating bath parameters on the impact energy absorbed have been plotted, and analysis has been carried out. Further, percentage contribution of coating bath parameters using Design of Experiments approach (DOE) has been analysed. Finally, it can be concluded that the bath parameters of the Ni-P coating will certainly influence on the strength of the specimen.

Keywords: bath parameters, coatings, design of experiment, fracture toughness, impact strength

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Authors: Asma Salman, Brian Gabbitas, Peng Cao, Deliang Zhang

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The performance of a coating is strongly dependent upon its microstructure, which in turn is dependent on the characteristics of the feedstock powder. This study involves the evaluation and performance of a titanium-based composite coating produced by the HVOF (high-velocity oxygen fuel) spraying method. The feedstock for making the composite coating was produced using high energy mechanical milling of TiO2 and Al powders followed by a combustion reaction. The characteristics of the feedstock powder were improved by treating it with an organic binder. Two types of coatings were produced using treated and untreated feedstock powders. The microstructures and characteristics of both types of coatings were studied, and their thermal shock resistance was accessed by dipping into molten aluminum. The results of this study showed that feedstock treatment did not have a significant effect on the microstructure of the coatings. However, it did affect the uniformity, thickness and surface roughness of the coating on the steel substrate. A coating produced by an untreated feedstock showed better thermal shock resistance in molten aluminum compared with the one produced by PVA (polyvinyl alcohol) treatment.

Keywords: coating, feedstock, powder processing, thermal shock resistance, thermally spraying

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Authors: Hyeong-Jin Kim, Jong Kook Lee

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Zirconia has biological, mechanical and optical properties, so, it used as a dental implant material in human body. But, it is difficult to form directly bonding with living tissues after the procedure and induces the falling away from implanted parts of the body. To improve this phenomenon, it is essential to increase the surface roughness of zirconia implants and induce a forming-ability of strong bonds. In this study, we performed a room temperature spray coating on zirconia specimen to obtain a highly roughened zirconia surface. To get optimal surface roughness, we controlled the distance between the nozzle and the substrate, coating times and powder condition. Bonding microstructure, surface roughness, and chemical composition of the coating layer were observed by SEM, XRD and roughness tester.

Keywords: implant, aerosoldeposition, zirconia, dental

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Authors: Nihit Madireddi, P. A. Mahanwar

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We have aimed to produce a self-cleaning transparent polymer coating with polyurethane (PU) matrix as the latter is highly solvent, chemical and weather resistant having good mechanical properties. Nano-silica modified by 1H, 1H, 2H, 2H-perflurooctyltriethoxysilane was incorporated into the PU matrix for attaining self-cleaning ability through hydrophobicity. The modification was confirmed by particle size analysis and scanning electron microscopy (SEM). Thermo-gravimetric (TGA) studies were carried to ascertain the grafting of silane onto the silica. Several coating formulations were prepared by varying the silica loading content and compared to a commercial equivalent. The effect of dispersion and the morphology of the coated films were assessed by SEM analysis. All coating standardized tests like solvent resistance, adhesion, flexibility, acid, alkali, gloss etc. have been performed as per ASTM standards. Water contact angle studies were conducted to analyze the hydrophobic character of the coating. In addition, the coatings were also subjected to salt spray and accelerated weather testing to analyze the durability of the coating.

Keywords: FAS, nano-silica, PU clear coat, self-cleaning

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Authors: Liping Wu, Durga Bhakta Pokharel, Junhua Dong, Changgang Wang, Lin Zhao, Wei Ke, Nan Chen

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Hazenite conversion coating was deposited on AZ31 Mg alloy in a deaerated phosphate solution containing 0.1 M K₂HPO₄ and 0.1 M Na₂HPO₄ (Na₀.₁K0₀.₁) with pH 9 at −0.8 V. The coating mechanism of hazenite was elucidated by in situ potentiostatic current decay, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), electron probe micro-analyzer (EPMA) and differential scanning calorimetry (DSC). The volume of H₂ evolved during potentiostatic polarization was measured by a gas collection apparatus. The degradation resistance of the hazenite coating was evaluated in simulated body fluid (SBF) at 37℃ by using potentiodynamic polarization (PDP). The results showed that amorphous Mg(OH)₂ was deposited first, followed by the transformation of Mg(OH)₂ to amorphous MgHPO₄, subsequently the conversion of MgHPO₄ to crystallized K-struvite (KMgPO₄·6H₂O), finally the crystallization of crystallized hazenite (NaKMg₂(PO₄)₂·14H₂O). The deposited coating was composed of four layers where the inner layer is comprised of Mg(OH)₂, the middle layer of Mg(OH)₂ and MgHPO₄, the top layer of Mg(OH)₂, MgHPO₄ and K-struvite, the topmost layer of Mg(OH)₂, MgHPO₄, K-struvite and hazenite (NaKMg₂(PO₄)₂·14H₂O). The PD results showed that the hazenite coating decreased the corrosion rate by two orders of magnitude.

Keywords: magnesium alloy, potentiostatic technique, hazenite, mineral conversion coating

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Authors: Haesook Kim, Ha Na Ra, Mansu Kim, Hyun Gi Kim, Sung Soo Kim

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Epoxy-ZrP (α-zirconium phosphate) nanocomposites were coated on inorganic barrier layer such as sputtering and atomic layer deposition (ALD) to improve the barrier properties and protect the layer. ZrP nanoplatelets were synthesized using a reflux method and exfoliated in the polymer matrix. The barrier properties of coating layer were characterized by measuring water vapor transmission rate (WVTR). The WVTR dramatically decreased after epoxy-ZrP nanocomposite coating, while maintaining the optical properties. It was also investigated the effect of epoxy-ZrP coating on inorganic layer after bending and reliability test. The optimal structure composed of inorganic and epoxy-ZrP nanocomposite layers was used in organic light emitting diodes (OLED) encapsulation.

Keywords: α-zirconium phosphate, barrier properties, epoxy nanocomposites, OLED encapsulation

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Authors: Feng Xu, Zhaozhi Liu, Junhua Xu, Xiaolong Tang, Dunwen Zuo

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Chemical vapor deposition (CVD) diamond coated cutting tool has excellent cutting performance, it is the most ideal tool for the processing of nonferrous metals and alloys, composites, nonmetallic materials and other difficult-to-machine materials efficiently and accurately. Depositing CVD diamond coating on the cemented carbide with high cobalt content can improve its toughness and strength, therefore, it is very important to research on the preparation technology and cutting properties of CVD diamond coated cemented carbide cutting tool with high cobalt content. The preparation technology of boron-doped diamond (BDD) coating has been studied and the coated drills were prepared. BDD coating were deposited on the drills by using the optimized parameters and the SEM results show that there are no cracks or collapses in the coating. Cutting tests with the prepared drills against the silumin and aluminum base printed circuit board (PCB) have been studied. The results show that the wear amount of the coated drill is small and the machined surface has a better precision. The coating does not come off during the test, which shows good adhesion and cutting performance of the drill.

Keywords: cemented carbide with high cobalt content, CVD boron-doped diamond, cutting test, drill

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Authors: N. Hadthamard, P. Chaumpluk, M. Buanong, P. Boonyaritthongchai, C. Wongs-Aree

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Ripe ‘Nam Dok Mai’ mango (Mangifera indica L.) is an important exported fruit of Thailand, but rapidly declined in the quality attributes mainly by infection of anthracnose and stem end rot diseases. Multilayer coating is considered as a developed technique to maintain the postharvest quality of mangoes. The utilization of alternated coating by matching oppositely electrostatic charges between 0.1% chitosan and 0.1% polystyrene sulfonate (PSS) was studied. A number of the coating layers (layer by layer) were applied on mature green ‘Nam Dok Mai No.4’ mangoes prior to storage at 25 ^oC, 65-70% relative humidity (RH). There were significant differences in some quality attributes of mangoes coated by 3½ layers, 4½ layers and 5½ layers. In comparison to coated mangoes, uncoated fruits were higher in weight loss, total soluble solids, respiration rate, ethylene production and disease incidence except the titratable acidity. Coating fruit at 3½ layers exhibited the ripening delay and reducing disease infection without off flavour. On the other hand, fruit coated with 5½ layers comprised the lowest acceptable score, caused by exhibiting disorders from fermentation at the end of storage. As a result, multilayer coating between chitosan and PSS could effectively maintain the postharvest quality of mango, but number of coating layers should be thoroughly considered.

Keywords: multilayer, chitosan, polystyrene sulfonate, Nam Dok Mai No.4

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Authors: H. B. Torane, M. C. Kasture, S. S. Prabhudesai, P. B. Sanap, V. N. Palsande, J. J. Palkar

Abstract:

The present investigation entitled “Response of briquettes application with different coating materials on yield and quality of Cucumber [Cucumis sativus (L.)]” was conducted at Central Experiment Center, Wakawali during kharif season 2013. The field experiment was laid out in Factorial Randomized Block Design with three replicate. The four coating materials viz., Co – Non coating, C1 – Wax coating, C2 – Jaggary coating, and C3 – Tar coating was applied to Konkan Annapurna Briquette along with three sub treatments of application time i.e B1 – ½ at sowing, B2 - ½ at sowing and ½ at 30 days after sowing and B3 - 1/3 at sowing, 1/3 at 30 days after sowing and 1/3 at 60 days after sowing. It was observed that the application of tar coated Konkan Annapurna Briquettes (KAB) in three times @1/3 quantity of briquettes at sowing time, 1/3 quantity of briquettes at 30 days after sowing and 1/3 quantity of briquettes at 60 days after sowing was found promising to enhancing the cucumber fruit yield, higher vine length, number of fruits vine-1, girth of fruit, length of fruit. It was also observed that the quality of the cucumber fruit increased in terms of ascorbic acid. UB-Godavari forms of briquettes .i.e. are promising source of N, P2O5 and K2O fertilizers as compared to straight fertilizers for enhancing green cucumber fruit yield of Sheetal variety of cucumber in lateritic soil. Amongst the three types of coated briquettes, the tar coated briquettes application was found to be superior for increasing cucumber fruit yield applied in three times @1/3 quantity of briquettes at sowing time, 1/3 quantity of briquettes at 30 days after sowing and 1/3 quantity of briquettes at 60 days after sowing @ 5 briquettes per plant at an interval of 30 days after sowing.

Keywords: briquettes, coating, yield, tar, wax and quality

Procedia PDF Downloads 487

Authors: Hamza Shams, Sajid Saleem, Bilal A. Siddiqui

Abstract:

This paper investigates the coefficient of friction at nano-levels of commercially available superhydrophobic/oleophobic coatings when applied over 316L SS. 316L Stainless Steel or Marine Stainless Steel has been selected for its widespread uses in structures, marine and biomedical applications. The coatings were investigated in harsh sand-storm and sea water environments. The particle size of the sand during the procedure was carefully selected to simulate sand-storm conditions. Sand speed during the procedure was carefully modulated to simulate actual wind speed during a sand-storm. Sample preparation was carried out using prescribed methodology by the coating manufacturer. The coating’s adhesion and thickness was verified before and after the experiment with the use of Scanning Electron Microscopy (SEM). The value for nano-level coefficient of friction has been determined using Lateral Force Microscopy (LFM). The analysis has been used to formulate a value of friction coefficient which in turn is associative of the amount of wear the coating can bear before the exposure of the base substrate to the harsh environment. The analysis aims to validate the coefficient of friction value as marketed by the coating manufacturers and more importantly test the coating in real-life applications to justify its use. It is expected that the coating would resist exposure to the harsh environment for a considerable amount of time. Further, it would prevent the sample from getting corroded in the process.

Keywords: 316L SS, scanning electron microscopy, lateral force microscopy, marine stainless steel, oleophobic coating, superhydrophobic coating

Procedia PDF Downloads 462

Authors: Venkat Garigapati

Abstract:

Cell-based therapies are limited due to underlying host immune system activity. Microencapsulation of living cells to overcome this issue has some serious drawbacks, such as limitations of nutrient and oxygen diffusion, which pose a threat to the function and longevity of cells. The conformal coating could overcome the issues which are generally involved in traditional microencapsulation. Some of the theoretical advantages of conformal coating include superior nutrient and oxygen supply to cells, prolonged lifespan, improved drug-secreting cell functionality and an opportunity to load high cell doses in small volumes. Despite several advantages to the conformal coating, there are no suitable methods available to apply to living cells. The ultra-thin conformal coating was achieved utilizing click-reactive methacryloyloxyethyl phosphorylcholine (MPC) polymers, which are capable of specifically reacting one polymer to another at neutral pH in the aqueous isotonic system at the desired temperature suitable for living cells without the need of deleterious initiators. ARPE-19 (Adult Retinal Pigment Epithelial cell line-19) cell-spheroids and rat pancreatic islets were used in the formulation studies. The in vitro studies of coated ARPE-19 cell-spheroids and rat islets indicate that the coat was intact; cells were viable and functioning. The in vitro study results revealed that the conformal coating technology seems promising and in vivo studies are being planned.

Keywords: cells, hydrogel, conformal coating, microencapsulation, insulin

Procedia PDF Downloads 67

Authors: Yu A. Pluttsova , O. V. Vakhnina , K. B. Zhogova

Abstract:

Nowadays, many devices operate under conditions of enhanced humidity, temperature drops, fog, and vibration. To ensure long-term and uninterruptable equipment operation under adverse conditions, one applies moisture-proof films on products and electronics components, which helps to prevent corrosion, short circuit, allowing a significant increase in device lifecycle. The reliability of such moisture-proof films is mainly determined by their coating uniformity without gaps and cracks. Unprotected product edges, as well as pores in films, can cause device failure during operation. The work objective was to develop an effective, affordable, and profit-proved method for determining the presence of through defects of protective polymer films on the surface of parts made of iron and its alloys. As a diagnostic reagent, one proposed water solution of potassium ferricyanide (III) in hydrochloric acid, this changes the color from yellow to blue according to the reactions; Feº → Fe²⁺ and 4Fe²⁺ + 3[Fe³⁺(CN)₆]³⁻ → Fe ³⁺4[Fe²⁺(CN)₆]₃. There was developed the principle scheme of technological process for determining the presence of polymer films through defects on the surface of parts made of iron and its alloys. There were studied solutions with different diagnostic reagent compositions in water: from 0,1 to 25 mass fractions, %, of potassium ferricyanide (III), and from 5 to 25 mass fractions, %, of hydrochloride acid. The optimal component ratio was chosen. The developed method consists in submerging a part covered with a film into a vessel with a diagnostic reagent. In the polymer film through defect zone, the part material (ferrum) interacts with potassium ferricyanide (III), the color changes to blue. Pilot samples were tested by the developed method for the presence of through defects in the moisture-proof coating. It was revealed that all the studied parts had through defects of the polymer film coating. Thus, the claimed method efficiently reveals polymer film coating through defects on parts made of iron or its alloys, being affordable and profit-proved.

Keywords: diagnostic reagent, metal parts, polimer films, through defects

Procedia PDF Downloads 124