The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
M M Attar - One of the best experts on this subject based on the ideXlab platform.
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electrochemical study of protective behavior of Organic Coating pigmented with zinc aluminum polyphosphate as a modified zinc phosphate at different pigment volume concentrations
Progress in Organic Coatings, 2009Co-Authors: R Naderi, M M AttarAbstract:Electrochemical impedance spectroscopy was employed to evaluate protective performance of the solvent-borne epoxy Coatings pigmented with zinc aluminum polyphosphate as a representative of phosphate-based anticorrosion compounds at different Lambda values. Furthermore, the effective ratio of the pigment volume concentration (PVC) to the critical pigment volume concentration (CPVC) was determined. To compare the function of zinc aluminum polyphosphate and zinc phosphate incorporated into Coatings, electrochemical noise method as well as electrochemical impedance spectroscopy was taken into consideration. The trend and magnitude of charge transfer, Coating and noise resistances plus the amplitude of the current noise fluctuation indicated superiority of the modified pigment. In order to provide an insight into the mechanism by which anticorrosion pigments improve protective behavior of Coating, performance of bare metals exposed to pigment extracts was assessed through taking advantage of electrochemical impedance spectroscopy and electrochemical noise method as well.
Eivaz H Mohammadloo - One of the best experts on this subject based on the ideXlab platform.
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effect of zirconium conversion Coating adhesion and anti corrosion properties of epoxy Organic Coating containing zinc aluminum polyphosphate zapp pigment on carbon mild steel
Progress in Organic Coatings, 2016Co-Authors: H R Asemani, P Ahmadi, A A Sarabi, Eivaz H MohammadlooAbstract:Abstract An epoxy Organic Coating containing zinc aluminum polyphosphate (ZAPP) pigments with and without a hexafluorozirconic acid based conversion Coating (ZrCC) pretreatment was applied on carbon mild steel (St 37) in order to investigate the corrosion resistance behavior and adhesion of the Coating to substrate. Optimization of pigment volume concentration (PVC) and conversion Coating application conditions was carried out and also the interaction of Organic and conversion Coating was studied using electrochemical impedance spectroscopy (EIS), salt spray and pull-off adhesion tests. Appropriate anti-corrosion properties was gained from Organic Coating samples with PVC = 30% and conversion Coating applied from a solution with pH and acid concentration of 4.5 and 0.01 M, respectively. Results indicated that using conversion Coating as a pretreatment before applying Organic Coating, improves adhesion of the Coating to the substrate (by 1–2 MPa) and also provides an effective corrosion protection in long periods of immersion time. The highest corrosion resistance was obtained for pigmented Organic Coating sample with Zr conversion Coating pretreatment after 4 weeks of immersion in NaCl 3.5 wt.%. Field emission scanning electron microscope and energy dispersive X-ray spectroscopy (FE-SEM/EDS) also proved the presence of about 5 wt.% of zirconium at the interface of Coating and substrate not only at the onset of immersion but also after 4 weeks of immersion time. Results taken from this research, can clarify the key role of surface modification at interface of Coating and substrate in adhesion and also the retention of anti-corrosion properties over the course of time even for an anti-corrosion pigment reinforced Organic Coating sample.
M M Atta - One of the best experts on this subject based on the ideXlab platform.
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surface free energy characterization and adhesion performance of mild steel treated based on zirconium conversion Coating a comparative study
Surface & Coatings Technology, 2014Co-Authors: A Ghanbari, M M AttaAbstract:Abstract The influence of zirconium based conversion Coating on the surface free energy and adhesion performance of an epoxy coated mild steel substrate was evaluated before and after post heating. Surface free energy components (γ LW , γ + and γ) of the mild steel were measured before and after surface treatment using van Oss–Good method. The obtained data revealed that after formation of the conversion layer, γ − component of the surface increased leading to increment of work of adhesion. This may be attributed to the formation of zirconium compounds and adsorbed fluoride ion on the steel surface, which are evident in the Field Emission Scanning Electron Microscopy (FE-SEM) and Energy Dispersive X-ray spectroscopy (EDX) results, respectively. Pull-off adhesion test was performed for variety of the surface treatments including zirconium conversion Coating (ZCC) and traditional phosphate and chromate layers. The results indicate that ZCC increased adhesion strength of mild steel to the Organic Coating and the zirconium treated mild steel adhesion performance is better than that of the three-cationic phosphate layer.
Ute Schlosmacher - One of the best experts on this subject based on the ideXlab platform.
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bioOrganic inOrganic hybrid composition of sponge spicules matrix of the giant spicules and of the comitalia of the deep sea hexactinellid monorhaphis
Journal of Structural Biology, 2008Co-Authors: Werner E. G. Müller, Alexandra Boreiko, Carsten Eckert, Klaus Kropf, Hiroshi Ushijima, Werner Geurtsen, Muhammad Nawaz Tahir, Wolfgang Tremel, Xiaohong Wang, Ute SchlosmacherAbstract:The giant basal spicules of the siliceous sponges Monorhaphis chuni and Monorhaphis intermedia (Hexactinellida) represent the largest biosilica structures on earth (up to 3 m long). Here we describe the construction (lamellar organization) of these spicules and of the comitalia and highlight their Organic matrix in order to understand their mechanical properties. The spicules display three distinct regions built of biosilica: (i) the outer lamellar zone (radius: >300 mu m), (ii) the bulky axial cylinder (radius: <75 mu m), and (iii) the central axial canal (diameter: <2 mu m) with its Organic axial filament. The spicules are loosely covered with a collagen net which is regularly perforated by 7-10 mu m large holes; the net can be silicified. The silica layers forming the lamellar zone are approximate to 5 mu m thick; the central axial cylinder appears to be composed of almost solid silica which becomes porous after etching with hydrofluoric acid (HF). Dissolution of a complete spicule discloses its complex structure with distinct lamellae in the outer zone (lamellar Coating) and a more resistant central part (axial barrel). Rapidly after the release of the Organic Coating from the lamellar zone the protein layers disintegrate to form irregular clumps/aggregates. In contrast, the proteinaceous axial barrel, hidden in the siliceous axial cylinder, is set up by rope-like filaments. Biochemical analysis revealed that the (dominant) molecule of the lamellar Coating is a 27-kDa protein which displays catalytic, proteolytic activity. High resolution electron microscopic analysis showed that this protein is arranged within the lamellae and stabilizes these surfaces by palisade-like pillars. The mechanical behavior of the spicules was analyzed by a 3-point bending assay, coupled with scanning electron microscopy. The load-extension curve of the spicule shows a biphasic breakage/cracking pattern. The outer lamellar zone cracks in several distinct steps showing high resistance in concert with comparably low elasticity, while the axial cylinder breaks with high elasticity and lower stiffness. The complex bioOrganic/inOrganic hybrid composition and structure of the Monorhaphis spicules might provide the blueprint for the synthesis of bio-inspired material, with unusual mechanical properties (strength, stiffness) without losing the exceptional properties of optical transmission. (C) 2007 Elsevier Inc. All rights reserved.
B Abdul J Aleem - One of the best experts on this subject based on the ideXlab platform.
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laser surface modification treatment of aluminum bronze with b4c
Applied Surface Science, 2012Co-Authors: Bekir Sami Yilbas, S S Akhtar, Cagdas Karatas, Adrian Leyland, A Matthews, B Abdul J AleemAbstract:Abstract One technique to improve tribological properties of aluminum bronze surfaces is to introduce laser controlled melting at the surface in the presence of a composition-modifying film. In this work, a 40 μm thick Organic film, containing B4C particles, was formed at the workpiece surface prior to laser treatment. The Organic Coating provides enhanced absorption of the incident laser radiation and distributes the B4C particles uniformly across the surface. Morphological and microstructural changes in the laser treated layer were examined using scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. The microhardness of the laser treated layer was measured and the residual stress formed at the treated surface was evaluated by X-ray diffraction using the sin2 ψ technique. It was found that the laser treated surface produced is relatively free from defects and asperities with a microhardness that is notably higher than that of the as-received bronze substrate. This hardening effect can be attributed to the development of a dense layer consisting of fine grains, partially dissolved B4C particles, and formation of Cu3N compounds. The residual compressive stress obtained from X-ray diffraction peak evaluation is of the order of −400 MPa.