The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
K. Ravichandran - One of the best experts on this subject based on the ideXlab platform.
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deposition of Zinc Zinc Phosphate composite coatings on aluminium by cathodic electrochemical treatment
Surface & Coatings Technology, 2014Co-Authors: C. Kavitha, T.s.n. Sankara Narayanan, K. RavichandranAbstract:Abstract The role of cathodic electrochemical treatment as an energy efficient and eco-friendly method to deposit Zinc–Zinc Phosphate composite coatings on Al is addressed. The deposition of Zinc–Zinc Phosphate composite coatings was carried out under galvanostatic conditions using an electrolyte solution containing 5 g/l of ZnO and 12 ml/l of o-phosphoric acid (85%), maintained at 27 ± 1 °C and two graphite disc anodes, placed on the two sides of the Al cathode. The applied current density (5 to 50 mA/cm 2 ), pH of the electrolyte (1.50, 2.30 and 3.00), treatment time (5 to 60 min) and concentration of ZnO (1 to 5 g/l) were used as the process variables. The methods of evaluation include, assessment of colour and uniformity by visual observations, adhesion by pull-off adhesion test, coating weight by a measure of gain in weight after deposition, morphological features by scanning electron microscopy, chemical composition by energy dispersive X-ray analysis and phase contents by X-ray diffraction studies. The corrosion resistance of the coatings, in 3.5% NaCl, was evaluated by potentiodynamic polarisation studies. The findings of this study reveal that the surface morphology, phase content and corrosion resistance of the composite coatings largely depend on the proportions of Zn and Zinc Phosphate in them. The cathodic electrochemical treatment method provides ample avenues to manipulate the volume fraction of Zn and Zinc Phosphate in the resultant composite coatings by a careful choice of the process parameters and hence, it is possible to deposit coatings on Al with varying degrees of corrosion protection.
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Deposition of Zinc–Zinc Phosphate composite coatings on steel by cathodic electrochemical treatment
Journal of Coatings Technology and Research, 2013Co-Authors: C. Kavitha, T.s.n. Sankara Narayanan, K. Ravichandran, Il Song ParkAbstract:The present work aims at the development of an energy-efficient and eco-friendly approach for the deposition of Zinc Phosphate coatings on steel. The study describes the possibility of preparing Zinc–Zinc Phosphate composite coatings by cathodic electrochemical treatment using dilute phosphoric acid as an electrolyte and Zinc as an anode. The methodology enables the preparation of coatings with different proportions of Zinc and Zinc Phosphate by suitably varying the applied current density, pH, and treatment time. Adhesion of the coating on mild steel and adhesion of paint film on the Phosphate coating were found to be good. The surface morphology of the coatings exhibited platelet-type features and small white crystals (agglomerated at some places) which represented Zinc and Zinc Phosphate, respectively. An increase in current density (from 20 to 50 mA/cm2) increased the size of the Zinc crystals, and coatings prepared at 40 and 50 mA/cm2 resembled that of electrodeposited Zinc. Since the proportions of Zinc and Zinc Phosphate could be varied with applied current density, pH, and treatment time, it would be possible to use this methodology to prepare coatings that would offer different degrees of corrosion protection.
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formation of Zinc Zinc Phosphate composite coatings by cathodic electrochemical treatment
Surface & Coatings Technology, 2006Co-Authors: S Jegannathan, T.s.n. Sankara Narayanan, K. Ravichandran, S RajeswariAbstract:The formation of Zinc–Zinc Phosphate composite coatings by cathodic electrochemical treatment and evaluation of its corrosion resistance is addressed in this paper. The cathodic phosphating process offers some unique advantages—it requires no specific addition of accelerator in the bath, it is capable of producing good quality coatings even at low temperature, it permits deposition of coatings of desired thickness, thus offering benefits in terms of energy savings, decrease in processing cost and improvement in plant life. Being a cathodic process, there is no iron dissolution and no ferric Phosphate sludge formation, which renders it an eco-friendly process. Based on the amount of coating mass as a function of process variables and the potential-time measurement, a pictorial model is proposed for the deposition of Zinc Phosphate coating. The surface morphology of the coatings exhibits plate-like crystals. The corrosion behaviour of cathodically Phosphated mild steel substrate in 3.5% sodium chloride solution exhibits the stability of these coatings, which last for a week with no red rust formation. This is due to the presence of a composite layer of Zinc and Zinc Phosphate that acts as a mechanical barrier against further corrosion for a considerably longer time. Being a cathodic process, the possibility of hydrogenation of steel is the major limitation of this methodology. D 2005 Elsevier B.V. All rights reserved.
T.s.n. Sankara Narayanan - One of the best experts on this subject based on the ideXlab platform.
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deposition of Zinc Zinc Phosphate composite coatings on aluminium by cathodic electrochemical treatment
Surface & Coatings Technology, 2014Co-Authors: C. Kavitha, T.s.n. Sankara Narayanan, K. RavichandranAbstract:Abstract The role of cathodic electrochemical treatment as an energy efficient and eco-friendly method to deposit Zinc–Zinc Phosphate composite coatings on Al is addressed. The deposition of Zinc–Zinc Phosphate composite coatings was carried out under galvanostatic conditions using an electrolyte solution containing 5 g/l of ZnO and 12 ml/l of o-phosphoric acid (85%), maintained at 27 ± 1 °C and two graphite disc anodes, placed on the two sides of the Al cathode. The applied current density (5 to 50 mA/cm 2 ), pH of the electrolyte (1.50, 2.30 and 3.00), treatment time (5 to 60 min) and concentration of ZnO (1 to 5 g/l) were used as the process variables. The methods of evaluation include, assessment of colour and uniformity by visual observations, adhesion by pull-off adhesion test, coating weight by a measure of gain in weight after deposition, morphological features by scanning electron microscopy, chemical composition by energy dispersive X-ray analysis and phase contents by X-ray diffraction studies. The corrosion resistance of the coatings, in 3.5% NaCl, was evaluated by potentiodynamic polarisation studies. The findings of this study reveal that the surface morphology, phase content and corrosion resistance of the composite coatings largely depend on the proportions of Zn and Zinc Phosphate in them. The cathodic electrochemical treatment method provides ample avenues to manipulate the volume fraction of Zn and Zinc Phosphate in the resultant composite coatings by a careful choice of the process parameters and hence, it is possible to deposit coatings on Al with varying degrees of corrosion protection.
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Deposition of Zinc–Zinc Phosphate composite coatings on steel by cathodic electrochemical treatment
Journal of Coatings Technology and Research, 2013Co-Authors: C. Kavitha, T.s.n. Sankara Narayanan, K. Ravichandran, Il Song ParkAbstract:The present work aims at the development of an energy-efficient and eco-friendly approach for the deposition of Zinc Phosphate coatings on steel. The study describes the possibility of preparing Zinc–Zinc Phosphate composite coatings by cathodic electrochemical treatment using dilute phosphoric acid as an electrolyte and Zinc as an anode. The methodology enables the preparation of coatings with different proportions of Zinc and Zinc Phosphate by suitably varying the applied current density, pH, and treatment time. Adhesion of the coating on mild steel and adhesion of paint film on the Phosphate coating were found to be good. The surface morphology of the coatings exhibited platelet-type features and small white crystals (agglomerated at some places) which represented Zinc and Zinc Phosphate, respectively. An increase in current density (from 20 to 50 mA/cm2) increased the size of the Zinc crystals, and coatings prepared at 40 and 50 mA/cm2 resembled that of electrodeposited Zinc. Since the proportions of Zinc and Zinc Phosphate could be varied with applied current density, pH, and treatment time, it would be possible to use this methodology to prepare coatings that would offer different degrees of corrosion protection.
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formation of Zinc Zinc Phosphate composite coatings by cathodic electrochemical treatment
Surface & Coatings Technology, 2006Co-Authors: S Jegannathan, T.s.n. Sankara Narayanan, K. Ravichandran, S RajeswariAbstract:The formation of Zinc–Zinc Phosphate composite coatings by cathodic electrochemical treatment and evaluation of its corrosion resistance is addressed in this paper. The cathodic phosphating process offers some unique advantages—it requires no specific addition of accelerator in the bath, it is capable of producing good quality coatings even at low temperature, it permits deposition of coatings of desired thickness, thus offering benefits in terms of energy savings, decrease in processing cost and improvement in plant life. Being a cathodic process, there is no iron dissolution and no ferric Phosphate sludge formation, which renders it an eco-friendly process. Based on the amount of coating mass as a function of process variables and the potential-time measurement, a pictorial model is proposed for the deposition of Zinc Phosphate coating. The surface morphology of the coatings exhibits plate-like crystals. The corrosion behaviour of cathodically Phosphated mild steel substrate in 3.5% sodium chloride solution exhibits the stability of these coatings, which last for a week with no red rust formation. This is due to the presence of a composite layer of Zinc and Zinc Phosphate that acts as a mechanical barrier against further corrosion for a considerably longer time. Being a cathodic process, the possibility of hydrogenation of steel is the major limitation of this methodology. D 2005 Elsevier B.V. All rights reserved.
C. Kavitha - One of the best experts on this subject based on the ideXlab platform.
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deposition of Zinc Zinc Phosphate composite coatings on aluminium by cathodic electrochemical treatment
Surface & Coatings Technology, 2014Co-Authors: C. Kavitha, T.s.n. Sankara Narayanan, K. RavichandranAbstract:Abstract The role of cathodic electrochemical treatment as an energy efficient and eco-friendly method to deposit Zinc–Zinc Phosphate composite coatings on Al is addressed. The deposition of Zinc–Zinc Phosphate composite coatings was carried out under galvanostatic conditions using an electrolyte solution containing 5 g/l of ZnO and 12 ml/l of o-phosphoric acid (85%), maintained at 27 ± 1 °C and two graphite disc anodes, placed on the two sides of the Al cathode. The applied current density (5 to 50 mA/cm 2 ), pH of the electrolyte (1.50, 2.30 and 3.00), treatment time (5 to 60 min) and concentration of ZnO (1 to 5 g/l) were used as the process variables. The methods of evaluation include, assessment of colour and uniformity by visual observations, adhesion by pull-off adhesion test, coating weight by a measure of gain in weight after deposition, morphological features by scanning electron microscopy, chemical composition by energy dispersive X-ray analysis and phase contents by X-ray diffraction studies. The corrosion resistance of the coatings, in 3.5% NaCl, was evaluated by potentiodynamic polarisation studies. The findings of this study reveal that the surface morphology, phase content and corrosion resistance of the composite coatings largely depend on the proportions of Zn and Zinc Phosphate in them. The cathodic electrochemical treatment method provides ample avenues to manipulate the volume fraction of Zn and Zinc Phosphate in the resultant composite coatings by a careful choice of the process parameters and hence, it is possible to deposit coatings on Al with varying degrees of corrosion protection.
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Deposition of Zinc–Zinc Phosphate composite coatings on steel by cathodic electrochemical treatment
Journal of Coatings Technology and Research, 2013Co-Authors: C. Kavitha, T.s.n. Sankara Narayanan, K. Ravichandran, Il Song ParkAbstract:The present work aims at the development of an energy-efficient and eco-friendly approach for the deposition of Zinc Phosphate coatings on steel. The study describes the possibility of preparing Zinc–Zinc Phosphate composite coatings by cathodic electrochemical treatment using dilute phosphoric acid as an electrolyte and Zinc as an anode. The methodology enables the preparation of coatings with different proportions of Zinc and Zinc Phosphate by suitably varying the applied current density, pH, and treatment time. Adhesion of the coating on mild steel and adhesion of paint film on the Phosphate coating were found to be good. The surface morphology of the coatings exhibited platelet-type features and small white crystals (agglomerated at some places) which represented Zinc and Zinc Phosphate, respectively. An increase in current density (from 20 to 50 mA/cm2) increased the size of the Zinc crystals, and coatings prepared at 40 and 50 mA/cm2 resembled that of electrodeposited Zinc. Since the proportions of Zinc and Zinc Phosphate could be varied with applied current density, pH, and treatment time, it would be possible to use this methodology to prepare coatings that would offer different degrees of corrosion protection.
Fuhui Wang - One of the best experts on this subject based on the ideXlab platform.
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the role of a Zinc Phosphate pigment in the corrosion of scratched epoxy coated steel
Corrosion Science, 2009Co-Authors: Yawei Shao, Guozhe Meng, Tao Zhang, Fuhui WangAbstract:The roles of a Zinc Phosphate pigment in the corrosion of scratched epoxy-coated steel were studied by means of electrochemical impedance spectroscopy, electrochemical noise measurement and scanning electrochemical microscopy. The experimental results of electrochemical noise measurement and electrochemical impedance spectroscopy revealed that Zinc Phosphate exhibited inhibition effect on the corrosion of the scratched epoxy-coated steel. The scanning electrochemical microscopy results implied that the scratched surface under Zinc Phosphate coating was re-healed by an insulating film. The mechanism of the inhibition effect of a Zinc Phosphate pigment was analyzed based upon the combined stochastic theory and shot noise theory using the Weibull distribution and Gumbel distribution function.
Yawei Shao - One of the best experts on this subject based on the ideXlab platform.
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the role of a Zinc Phosphate pigment in the corrosion of scratched epoxy coated steel
Corrosion Science, 2009Co-Authors: Yawei Shao, Guozhe Meng, Tao Zhang, Fuhui WangAbstract:The roles of a Zinc Phosphate pigment in the corrosion of scratched epoxy-coated steel were studied by means of electrochemical impedance spectroscopy, electrochemical noise measurement and scanning electrochemical microscopy. The experimental results of electrochemical noise measurement and electrochemical impedance spectroscopy revealed that Zinc Phosphate exhibited inhibition effect on the corrosion of the scratched epoxy-coated steel. The scanning electrochemical microscopy results implied that the scratched surface under Zinc Phosphate coating was re-healed by an insulating film. The mechanism of the inhibition effect of a Zinc Phosphate pigment was analyzed based upon the combined stochastic theory and shot noise theory using the Weibull distribution and Gumbel distribution function.
