Journal of Coatings http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. Simultaneous Bacillus anthracis Spores Detection via Aminated-Poly(vinyl chloride) Coated Piezoelectric Crystal Immunosensor Tue, 19 Aug 2014 13:15:07 +0000 http://www.hindawi.com/journals/jcoat/2014/256168/ Bacillus anthracis spores are a potential threat to countries in the context of biodefense. We have already seen the destructiveness of the anthrax attacks in the recent past. This study presents an aminated-poly(vinyl chloride) (PVC-NH2) coated quartz crystal microbalance (QCM) immunosensor for simultaneous rapid detection of B. anthracis spores. PVC-NH2, synthesized in the laboratory, was used as an adhesive layer for monoclonal antibody immobilization on gold quartz crystal. The prepared QCM sensor was tested using a pathogen field strain of B. anthracis (GenBank number: GQ375871.1) under static addition and flow through procedures with different spore concentrations. Fourier transform infrared spectroscopy (FTIR-ATR) and scanning electron microscopy (SEM) were performed to characterize the surface of the sensor during the modification. Furthermore, a series of SEM micrographs were taken in order to investigate surface morphology and show the presence of the B. anthracis spores on the surface. It is concluded that B. anthracis spores can be accomplished by using amine functionalized polymer coated QCM sensors without requiring complicated immobilization procedures or expensive preliminary preparations. Ali Oztuna, Hasan Nazir, and Mehmet Baysallar Copyright © 2014 Ali Oztuna et al. All rights reserved. Studies on the Codeposition of SiC Nanopowder with Nickel, Cobalt, and Co-Ni Alloys Wed, 23 Jul 2014 10:05:57 +0000 http://www.hindawi.com/journals/jcoat/2014/659697/ Electrodeposition of SiC nanopowder (approximately 120 nm) with nickel, cobalt, and Co-Ni alloy matrix was studied. It was found that particles suspended in the bath affect slightly the reduction of metallic ions. Incorporation of the ceramic particles was governed mainly by the morphology of the matrix surface, while no strict correlation between the amount of cobalt ions adsorbed on the powder and the SiC content in the composites was found. Microhardness of nickel deposits was  HV, while for cobalt-rich coatings (84–95 wt.% Co) the values were in the range of 260–290 HV, independently of the SiC content in the coatings. Fine-grained nickel deposits were characterized by good corrosion resistance, while cobalt and Co-Ni alloys showed high corrosion current densities. Ewa Rudnik and Sławomir Syrek Copyright © 2014 Ewa Rudnik and Sławomir Syrek. All rights reserved. Effect of Methyltrimethoxy Silane Modification on Yellowing of Epoxy Coating on UV (B) Exposure Wed, 11 Jun 2014 07:10:43 +0000 http://www.hindawi.com/journals/jcoat/2014/515470/ The exterior durability of epoxies is severely affected due to its poor weathering resistance. Epoxies exhibit chalking and discoloration under UV exposure caused as a result of photodegradation. The present work aims at studying the extent to which the color change and yellowing caused due to weathering under accelerated weathering conditions, of DGEBA epoxy, could be lowered by in situ modification of the epoxy polymer backbone with a silane, namely, MTMS. The epoxy resin and silane-modified epoxy resin were formulated into a TiO2-based white coating, applied on mild steel panels, and exposed in a UV (B) weatherometer. The color change (dE) and yellowness index (YI) values of weathered panels were evaluated using a spectrophotometer. The weathered samples were also characterized using FTIR-imaging technique to study the effect of weathering on the structural backbone of the formulated coatings. The silane-modified epoxy coatings showed lowered yellowing by 45% on UV exposure and the enhanced resistance to yellowing of the modified coatings was indicated by lowered dE and YI values. The enhanced resistance to yellowing by the silane-modified epoxy was attributed to the strengthening of the epoxy backbone by introduction of Si–O–C linkage onto the epoxy polymeric chain. Narayani Rajagopalan and A. S. Khanna Copyright © 2014 Narayani Rajagopalan and A. S. Khanna. All rights reserved. Dependence of Adhesion Property of Epoxidized Natural Rubber (ENR 25)/Ethylene-Propylene-Diene Rubber Blend Adhesives Crosslinked by Benzoyl Peroxide Thu, 29 May 2014 05:21:34 +0000 http://www.hindawi.com/journals/jcoat/2014/526369/ The loop tack, peel strength, and shear strength of crosslinked epoxidized natural rubber (ENR 25)/ethylene-propylene-diene rubber (EPDM) blend adhesives were investigated. Coumarone-indene resin, toluene, and benzoyl peroxide were used as the tackifier, solvent, and crosslinking agent, respectively, throughout the experiment. The adhesive was coated on a polyethylene terephthalate (PET) substrate using a SHEEN hand coater at 60 μm and 120 μm coating thickness. It was cured at 80°C for 30 minutes before testing on a Lloyd adhesion tester operating at testing rates from 10 to 60 cm min−1. Results show that loop tack and peel strength of the ENR 25/EPDM adhesive pass through a maximum value at 2 parts per hundred parts of rubber (phr) of benzoyl peroxide content. This observation is attributed to the increase in crosslinking which enhances the cohesive strength of the adhesive. Further addition of the crosslinking agent decreases the tack and peel strength due to the decrease in wettability of the over-crosslinked adhesive. Shear strength, however, increases steadily with benzoyl peroxide content, an observation which is associated with the steady increase in the cohesive strength. The adhesion properties increase with increasing coating thickness and testing rate. B. T. Poh and Y. Y. Teh Copyright © 2014 B. T. Poh and Y. Y. Teh. All rights reserved. Adhesion Properties of Acrylonitrile-Butadiene Rubber/Standard Malaysian Rubber Blend Based Pressure-Sensitive Adhesive Thu, 24 Apr 2014 06:50:11 +0000 http://www.hindawi.com/journals/jcoat/2014/369352/ Viscosity and adhesion properties of NBR/SMR L blend based pressure-sensitive adhesive were investigated using coumarone-indene resin, toluene, and poly(ethylene terephthalate) (PET) as tackifier, solvent, and coating substrate, respectively. Coumarone-indene resin content was fixed at 40 parts per hundred parts of rubber (phr) in the adhesive formulation. The ratio of NBR/SMR L blend used was 0, 20, 40, 60, 80, and 100% of NBR content. Four different thicknesses, that is, 30, 60, 90, and 120 µm, were used to coat the PET film. The viscosity of adhesive was determined by a Brookfield viscometer, whereas loop tack, peel strength, and shear strength were measured using a Lloyd Adhesion Tester operating at 30 cm/min. Result indicates that the viscosity, loop tack, and shear strength of blend adhesives increase with % NBR. However, for peel strength, it indicates a maximum at 40% NBR blend ratio for the three modes of peel tests. In all cases, 120 µm coated sample consistently exhibits the highest adhesion values compared to the other coating thicknesses, an observation which is associated with the higher volume of adhesive in the former system. B. T. Poh, J. Lamaming, and G. S. Tay Copyright © 2014 B. T. Poh et al. All rights reserved. Development of Epoxy Based Surface Tolerant Coating Improvised with Zn Dust and MIO on Steel Surfaces Thu, 03 Apr 2014 13:28:07 +0000 http://www.hindawi.com/journals/jcoat/2014/574028/ Couple of high strength and flexible surface tolerant coatings were designed for oil contaminated, rusty, and minimally prepared steel surfaces. These coatings are to have strong interfacial adhesion due to low surface tension and sustain more than 5 MPa pull out force consistently. The effect of optimized concentration of zinc dust and micaceous iron oxide (MIO) as pigments is evaluated for these surface tolerant coating systems. It has been noticed that the presence of these two ingredients has enhanced corrosion resistance more than several times as compared to commercially available coating systems. The corrosion simulation test in 3.5 wt.% NaCl has evident for significant improvement in terms of delaying blistering and delamination. The high pore resistance () indicates the slow migration of ions and water into the substrate and coating interface, which could be the reason of the improvement in corrosion process. Rachna Jain, Manish Wasnik, Amit Sharma, Manish Kr Bhadu, T. K. Rout, and A. S. Khanna Copyright © 2014 Rachna Jain et al. All rights reserved. Structure and Friction Behavior of Cr/a-C:H Nanocomposite Films Sun, 23 Feb 2014 09:28:26 +0000 http://www.hindawi.com/journals/jcoat/2014/902031/ CrN and Cr/a-C:H nanocomposite films were deposited on Si substrates by the magnetron sputtering technique. The structure, chemical state, and friction behavior of the Cr/a-C:H films prepared at various CH4 content were studied systematically. The CrN film shows strong (111) and (220) orientation, while the Cr/a-C:H films consist of the nanocrystalline Cr or Cr particles embedded in an amorphous hydrocarbon (a-C:H) matrix and show weak diffraction peaks, which is in accordance with the XPS analysis results. The typical Raman D and G peaks are observed, indicating that the separated amorphous carbon or C phase appears in the Cr/a-C:H films. However, no chromium carbide was observed in all the as-deposited samples. From the SEM graphs, all the deposited films depicted a dense and compact microstructure with well-attached interface with the substrate. The average friction coefficient of the Cr/a-C:H films largely decreased with increasing CH4 content. Lunlin Shang, Guangan Zhang, and Zhongrong Geng Copyright © 2014 Lunlin Shang et al. All rights reserved. Hydrogenated Silicon Carbide Thin Films Prepared with High Deposition Rate by Hot Wire Chemical Vapor Deposition Method Tue, 04 Feb 2014 11:20:20 +0000 http://www.hindawi.com/journals/jcoat/2014/905903/ Structural, optical, and electrical properties of hydrogenated silicon carbide (SiC:H) films, deposited from silane (SiH4) and methane (CH4) gas mixture by HW-CVD method, were investigated. Film properties are carefully and systematically studied as function of deposition pressure which is varied between 200 mTorr and 500 mTorr. The deposition rate is found to be reasonably high (9.4 nm/s 15.54 nm/s). Formation of SiC:H films is confirmed by FTIR, Raman, and XPS analysis. XRD and Raman analysis revealed that with increasing deposition pressure amorphization occurs in SiC:H films. FTIR spectroscopy analysis shows that bond density of C–H decreases while Si–C and Si–H bond densities increase with increasing deposition pressure. Total hydrogen content increases with increasing deposition pressure and was found to be <20 at.%. The absence of band ~1300–1600 cm−1 in the Raman spectra implies negligible C–C bond concentration and formation of nearly stoichiometric SiC:H films. The band gap shows increasing trend with increasing deposition pressure. The high value of Urbach energy suggests increased structural disorder in SiC:H films. Finally, it has been concluded that CH4 can be used as effective carbon source in HW-CVD method to prepare stoichiometric SiC:H films. M. M. Kamble, V. S. Waman, A. H. Mayabadi, S. S. Ghosh, B. B. Gabhale, S. R. Rondiya, A. V. Rokade, S. S. Khadtare, V. G. Sathe, T. Shripathi, H. M. Pathan, S. W. Gosavi, and S. R. Jadkar Copyright © 2014 M. M. Kamble et al. All rights reserved. Evaluation and Characterization of Plasma Sprayed Cu Slag-Al Composite Coatings on Metal Substrates Wed, 25 Dec 2013 10:16:24 +0000 http://www.hindawi.com/journals/jcoat/2013/842865/ Copper slag is a waste product obtained during matte smelting and refining of copper. The present work explores the coating potential of copper slag by plasma spraying. This work shows that copper slag is eminently coatable. An attempt has been made in the present investigation to use the composites coatings of copper slag and Al powder in suitable combination on aluminium and mild steel substrates in order to improve the surface properties of these ductile metal-alloy substrates. When premixed with Al powder, the coating exhibits higher interfacial adhesion as compared to pure copper slag coatings. Maximum adhesion strengths of about 23 MPa and 21 MPa are recorded for the coatings of copper slag with 15 wt% of Al on aluminium and mild steel substrates, respectively. The input power to the plasma torch is found to affect the coating deposition efficiency and morphology of the coatings. It also suggests value addition of an industrial waste. S. Mantry, B. B. Jha, and A. Satapathy Copyright © 2013 S. Mantry et al. All rights reserved. Optimization of Electroless Ni-P-W Coatings for Minimum Friction and Wear Using Grey-Taguchi Method Wed, 25 Dec 2013 09:13:09 +0000 http://www.hindawi.com/journals/jcoat/2013/608140/ The present experimental investigation deals with the deposition of electroless Ni-P-W coating on mild steel substrate and optimization of tribological parameters for better tribological behaviour like minimization of wear depth and coefficient of friction. Three tribological test parameters, namely, load, speed, and time, are optimized for minimum friction and wear of the coating. Friction and wear tests are carried out in a multitribotester using block on roller configuration under dry conditions. Taguchi based grey relational analysis is employed for optimization of this multiple response problem using L27 orthogonal array. Analysis of variance shows that load, speed, time, and interaction between load and speed have significant influence on controlling the friction and wear behavior of Ni-P-W coating. It is observed that wear mechanism is mild adhesive in nature. The structural morphology, composition, and phase structure of the coating are studied with the help of scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and X-ray diffraction analysis (XRD), respectively. Supriyo Roy and Prasanta Sahoo Copyright © 2013 Supriyo Roy and Prasanta Sahoo. All rights reserved. Dependence of Adhesion Properties on Blend Ratio of Ethylene-Propylene-Diene Rubber/Standard Malaysian Rubber Blend Adhesive Tue, 17 Dec 2013 10:24:46 +0000 http://www.hindawi.com/journals/jcoat/2013/383276/ Viscosity, tack and, peel and shear strengths of ethylene-propylene-diene rubber (EPDM)/standard Malaysian rubber (SMR L) blend adhesive were studied using various blend ratios of the two rubbers, ranging from 0 to 100% EPDM. Coumarone-indene resin, toluene, and poly(ethylene terephthalate) (PET) were used as the tackifier, solvent, and coating substrate, respectively. The tackifier content was fixed at 40 parts per hundred parts of rubber (phr). A SHEEN hand coater was used to coat the adhesive on PET film at four coating thicknesses, that is, 30, 60, 90, and 120 µm. The viscosity and adhesion properties were determined by a Brookfield viscometer and a Lloyd Adhesion Tester, respectively. Results show that the viscosity, loop tacks and peel strength of blend adhesives decrease gradually with increasing % EPDM. This observation is attributed to dilution effect and lowering in wettability and compatibility. Shear strength, however, passes through a maximum at 20–40% EPDM blend ratio, an observation which is ascribed to culmination of cohesive strength at the optimum EPDM blend ratio. Increasing coating thickness increases the adhesion properties in all blend ratios in this study. B. T. Poh, J. Lamaming, and G. S. Tay Copyright © 2013 B. T. Poh et al. All rights reserved. Properties of TiC Coating by Pulsed DC PACVD Mon, 25 Nov 2013 18:28:00 +0000 http://www.hindawi.com/journals/jcoat/2013/712812/ In the PACVD technique, temperature and gas flow rate are two important parameters affecting the coating characteristics. Effect of these parameters on mechanical behaviors of TiC coating that was deposited on hot work tool steel (H13) was investigated in this paper. We analyzed TiC coating composition and structure with grazing incidence X-ray diffraction (GIXRD) and Fourier transformation infrared spectroscopy (FTIR). The mechanical properties of the coatings, such as microhardness, wear resistance, and surface roughness, were studied with Knoop hardness indentation, pin on disk wear tests, and atomic force microscopy, respectively. When the deposition temperature decreased from 490°C to 450°C and the CH4 to TiCl4 flow rate ratio was also increased from 1.5 to 6, TiC coating color changed from dark gray to silver. The best mechanical properties such as a high hardness (27 GPa), wear resistance, and low surface roughness were related to the coating that was deposited at 450°C. Mahboobeh Azadi, Alireza Sabour Rouhaghdam, and Shahrokh Ahangarani Copyright © 2013 Mahboobeh Azadi et al. All rights reserved. Photoconductive Properties of Brush Plated Copper Indium Gallium Selenide Films Thu, 31 Oct 2013 15:33:39 +0000 http://www.hindawi.com/journals/jcoat/2013/109176/ Copper indium gallium selenide (CIGS) films were deposited for the first time by the brush electrodeposition technique. X-ray diffraction studies indicated the formation of single phase chalcopyrite CIGS. Lattice parameters, dislocation density, and strain were calculated. Band gap of the films increased from 1.12 eV to 1.63 eV as the gallium concentration increased. Room temperature transport parameters of the films, namely, resistivity increased from 0.10 ohm cm to 12 ohm cm, mobility decreased from 125 cm2V−1s−1 to 20.9 cm2V−1s−1, and carrier concentration decreased from 4.99 × 1017 cm−3 to 2.49 × 1016 cm−3 as the gallium concentration increased. Photosensitivity of the films increased linearly with intensity of illumination and with increase of applied voltage. N. P. Subiramaniyam, P. Thirunavukkarasu, and K. R. Murali Copyright © 2013 N. P. Subiramaniyam et al. All rights reserved. Effect of Testing Rate on Adhesion Properties of Acrylonitrile-Butadiene Rubber/Standard Malaysian Rubber Blend-Based Pressure-Sensitive Adhesive Sun, 20 Oct 2013 09:46:40 +0000 http://www.hindawi.com/journals/jcoat/2013/519416/ The dependence of loop tack, peel strength, and shear strength of NBR/SMR L blend-based pressure-sensitive adhesives on the rate of testing was investigated using coumarone-indene resin and toluene as the tackifier and solvent, respectively. A 40% NBR content in the NBR/SMR L blend was used throughout the experiment. The adhesion properties were measured by a Lloyd Adhesion Tester operating at different rates of testing. The result indicates that loop tack, peels strength, and shear strength increase with the rate of testing due to the viscoelastic response of the adhesive. At low testing rate, the failure mode is cohesive in nature whereas adhesion failure mode occurs at higher testing rates. Adhesion properties also increase with the increase in adhesive coating thickness, an observation which is attributed to the wettability of the adhesive and viscoelastic behavior of the rubber blend. B. T. Poh and Junidah Lamaming Copyright © 2013 B. T. Poh and Junidah Lamaming. All rights reserved. A Study on the Thermodynamics of Grain Growth in R.F. Magnetron Sputtered NiO Thin Films Mon, 23 Sep 2013 14:42:45 +0000 http://www.hindawi.com/journals/jcoat/2013/981515/ Postdeposition annealing of thin nickel films synthesized using R.F. magnetron sputtering technique is carried in this study. The XRD analysis indicates that annealing of the nickel films leads to the formation of nickel oxide with a preferential growth along (200) plane. The oxidation mechanism is observed with a phase transformation and results in polycrystalline NiO films. The surface morphology of the thin films was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM) as a function of annealing temperature. The studies indicate the formation of well-defined grain boundaries due to agglomeration of nanocrystallites. The films annealed in the range 573–773 K are found to be porous. The optical transmission spectra of the films annealed at 773 K exhibit interference effects for photon energies below the fundamental absorption edge. The optical studies indicate the existence of direct interband transition across a bandgap of 3.7 eV in confirmation with earlier band structure calculations. I. Dhanya and B. Sasi Copyright © 2013 I. Dhanya and B. Sasi. All rights reserved. Hot-Dip Aluminizing of Low Carbon Steel Using Al-7Si-2Cu Alloy Baths Thu, 19 Sep 2013 08:39:30 +0000 http://www.hindawi.com/journals/jcoat/2013/180740/ Hot-dip aluminizing of low carbon steel was done in molten Al-7Si-2Cu bath at 690°C for dipping time ranging from 300 to 2400 seconds. Characterization of the intermetallics layer was done by using scanning electron microscope with energy dispersive spectroscopy. Four intermetallic phases, -Al7Fe2Si, -FeAl3, -Fe2Al5, and -Al2Fe3Si3, were identified in the reaction layer. - Al7Fe2Si phase was observed adjacent to aluminum-silicon topcoat, -FeAl3 between and -Fe2Al5, -Fe2Al5 adjacent to base material, and -Al2Fe3Si3 precipitates within Fe2Al5 layer. The average thickness of Fe2Al5 layer increased linearly with square root of dipping time, while for the rest of the layers such relationship was not observed. The tongue-like morphology of Fe2Al5 layer was more pronounced at higher dipping time. Overall intermetallic layer thickness was following parabolic relationship with dipping time. Prashanth Huilgol, Suma Bhat, and K. Udaya Bhat Copyright © 2013 Prashanth Huilgol et al. All rights reserved. Friction and Wear Properties of Cold Gas Dynamic Sprayed Composite Coatings Wed, 31 Jul 2013 13:21:42 +0000 http://www.hindawi.com/journals/jcoat/2013/613178/ Different proportions of α-Al2O3 and pure Al powders were coated onto AZ91D magnesium alloy substrates by cold gas dynamic spray. The microstructure and morphologies of the coatings were observed by scanning electron microscope. The friction and wear properties were tested by a ball-on-disk wear tester. It was found that the interfaces between grains and substrates formed close boundaries. It is revealed that the composite coatings could increase the friction or wear properties of the coatings. It was observed that the wear of coatings was converted from adhesive wear into abrasive wear with α-Al2O3 particles increasing and that the adhesive wear accompanied with abrasive wear would increase the wear rate of coatings. Jie Wu, Yongshan Tao, Huazi Jin, Ming Li, Tianying Xiong, and Chao Sun Copyright © 2013 Jie Wu et al. All rights reserved. Studies on Nanocomposite Conducting Coatings Wed, 10 Jul 2013 10:17:48 +0000 http://www.hindawi.com/journals/jcoat/2013/260638/ Nanocomposite conducting coatings can impart stable surface electrical conductivity on the substrate. In this paper, carbon nanofiber (CNF) and nanographite (NG) are dispersed in thermoplastic polyurethane matrix and coated on the surface of glass and polyethylene terephthalate (PET) film. The nanoparticles dispersion was studied under TEM. The coating thicknesses were estimated. Further, their resistance and impedance were measured. It has been observed that the 5 wt% CNF dispersed nanocomposite coatings show good conductivity. The use of NG can bring down the amount of CNF; however, NG alone has failed to show significant improvement in conductivity. The nanocomposite coating on PET film using 2.5 wt% of both CNF and NG gives frequency-independent impedance which indicates conducting network formation by the nanoparticles. The study was carried out at different test distances on nanocomposite coated PET films to observe the linearity and continuity of the conducting network, and the result shows reasonable linearity in impedance over total test length (from 0.5 cm to 4.5 cm). The impedance of nanocomposite coatings on glass is not frequency independent and also not following linear increase path with distance. This indicates that the dispersion uniformity is not maintained in the coating solution when it was coated on glass. Amitava Bhattacharyya and Gopinathan Janarthanan Copyright © 2013 Amitava Bhattacharyya and Gopinathan Janarthanan. All rights reserved. Fabrication of Transparent Conductive Zinc Oxide Co-Doped with Fluorine and Zirconium Thin Solid Films by Ultrasonic Chemical Pyrolysis: Effects of Precursor Solution Aging and Substrate Temperature Mon, 08 Jul 2013 09:25:12 +0000 http://www.hindawi.com/journals/jcoat/2013/519140/ Highly transparent, conducting zinc oxide [ZnO] thin films co-doped with fluorine and zirconium have been deposited on glass substrates by the ultrasonic chemical spraying technique. The effects of aging of the starting solution and substrate temperature on the structural, morphological, and electrical properties of the ZnO:F:Zr films have been studied. The resistivity of the films decreases with the aging time of the starting solution until the seventeenth day reaching a minimum of about  Ω cm and then increases. Though all the samples are of polycrystalline hexagonal wurtzite type and grow preferentially with (002) plane parallel to the substrate, their morphology depends strongly on the aging time of the reaction solution. The optical transmittance of all the films remained around 80% in the visible spectral range. These highly transparent, low resistive thin films are expected to be highly useful as transparent electrodes in the fabrication of thin film solar cells. Luis Castañeda Copyright © 2013 Luis Castañeda. All rights reserved. Tribological Characteristics Improvement of Wear Resistant MAO-Coatings Wed, 19 Jun 2013 18:36:45 +0000 http://www.hindawi.com/journals/jcoat/2013/262310/ Currently, the most promising technology of coating formation is microarc oxidation (MAO) with unique properties of the surface layer, which combine high wear resistance, corrosion resistance, and heat and erosion resistance. Microarc oxidation can be used for parts and components manufacturing in various segments of industries. However, the technology improvement by improving the tribological characteristics of MAO-coatings can not only enhance economic effect, but also expand its application. V. N. Malyshev, A. M. Volkhin, and B. M. Gantimirov Copyright © 2013 V. N. Malyshev et al. All rights reserved.