The Experts below are selected from a list of 723 Experts worldwide ranked by ideXlab platform
Wei Gao - One of the best experts on this subject based on the ideXlab platform.
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Electrochemical studies of sol-enhanced Zn–Ni–Al2O3 composite and Zn–Ni alloy coatings
Journal of Electroanalytical Chemistry, 2015Co-Authors: Soroor Ghaziof, Paul A. Kilmartin, Wei GaoAbstract:Abstract Zn–Ni–Al 2 O 3 nano-composite coatings were Electrodeposited on mild steel using a novel sol enhanced Electroplating method. The effect of alumina sol on the Electrodeposition process, and coating properties was investigated using cyclic voltammetry, chronoamperometry and Electrochemical impedance spectroscopy. The results indicated that the Electro-Crystallization processes of Zn–Ni and Zn–Ni–Al 2 O 3 were governed by a three-dimensional nucleation process controlled by diffusion. Evaluation of nucleation mode in the presence and absence of alumina sol showed that the progressive nucleation was predominant for the Zn–Ni alloy deposit. However, for the Zn–Ni composite coating, the nucleation mode was closer to instantaneous nucleation. Nucleation parameters such as density of active nucleation sites and nucleation rate were increased in the presence of alumina nano-particles in the bath. Zn–Ni–Al 2 O 3 nano composite coatings produced more uniform and compact deposits, with fine grained microstructure when compared to Zn–Ni coatings. XRD results showed that the phase structure of both alloy and composite coatings was single Ni 5 Zn 21 -γ phase, and that the incorporation of alumina in the Zn–Ni coating refined the crystal grain size.
Naresh Mameda - One of the best experts on this subject based on the ideXlab platform.
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Cryolite (Na3AlF6) Crystallization for fluoride recovery using an Electrolytic process equipped with a sacrificial aluminum anode.
Journal of hazardous materials, 2019Co-Authors: Chen Yi-chieh, Yi-hsuan Chou, Kwang-ho Choo, Jhy-chern Liu, Naresh MamedaAbstract:An Electro-Crystallization process equipped with a sacrificial aluminum anode was operated under an optimum condition to promote the formation of crystalline cryolite for the recovery of fluoride from synthetic F-containing wastewater. The effects of pH, Al/F molar ratio, initial F concentration, and Electrolytes were investigated experimentally, and the results were compared with data obtained from chemical equilibrium modeling. Cryolite was successfully produced under optimum pH values of 5 to 6 and Al/F molar ratios of less than 1/6. The F removal increased with increasing Al/F molar ratio until reaching the molar ratio of 1/6 and decreased thereafter due to the formation of AlFn3-n species. The adsorption of AlFn3-n by Al(OH)3 precipitates contributed part of F removal. The removal efficiency reached 100% when the initial fluoride concentration was high while it was around 90% with the low initial fluoride concentration. XRD and SEM/EDX analysis showed that the obtained solids matched well to the commercial cryolite. Finally, the operating costs of chemical-Crystallization (the process with Al ions added chemically) and Electro-Crystallization were compared, and the cost of the former was less than the latter. Energy consumption was the main contributor to the operating cost of the Electro-Crystallization process.
Fan Jiang - One of the best experts on this subject based on the ideXlab platform.
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Tungsten coatings Electro-deposited on CFC substrates from oxide molten salt
Journal of Nuclear Materials, 2014Co-Authors: Ningbo Sun, Yingchun Zhang, Fan Jiang, Shaoting Lang, Lili WangAbstract:Abstract Tungsten is considered as plasma facing material in fusion devices because of its high melting point, its good thermal conductivity, its low erosion rate and its benign neutron activation properties. On the other hand, carbon based materials like C/C fiber composites (CFC) have been used for plasma facing materials (PFMs) due to their high thermal shock resistance, light weight and high strength. Tungsten coatings on CFC substrates are used in the JET divertor in the frame of the JET ITER-like wall project, and have been prepared by plasma spray (PS) and other techniques. In this study, tungsten coatings were Electro-deposited on CFC from Na 2 WO 4 –WO 3 molten salt under various deposition parameters at 900 °C in air. In order to obtain tungsten coatings with excellent performance, the effects of pulse duration ratio and pulse current density on microstructures and crystal structures of tungsten coatings were investigated by X-ray diffraction (XRD, Rigaku Industrial Co., Ltd., D/MAX-RB) and a scanning Electron microscope (SEM, JSM 6480LV). It is found that the pulsed duration ratio and pulse current density had a significant influence on tungsten nucleation and Electro-Crystallization phenomena. SEM observation revealed that intact, uniform and dense tungsten coatings formed on the CFC substrates. Both the average grain size and thickness of the coating increased with the pulsed current density. The XRD results showed that the coatings consisted of a single phase of tungsten with the body centered cubic (BCC) structure. The oxygen content of Electro-deposited tungsten coatings was lower than 0.05%, and the micro-hardness was about 400 HV.
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Electrodeposition of metallic tungsten coating from binary oxide molten salt on low activation steel substrate
Journal of Nuclear Materials, 2013Co-Authors: Yanhong Liu, Yingchun Zhang, Fan Jiang, Ningbo SunAbstract:Abstract Tungsten is considered a promising plasma facing armor material for future fusion devices. An Electrodeposited metallic tungsten coating from Na 2 WO 4 –WO 3 binary oxide molten salt on low activation steel (LAS) substrate was investigated in this paper. Tungsten coatings were deposited under various pulsed currents conditions at 1173 K in atmosphere. Cathodic current density and pulsed duty cycle were investigated for pulsed current Electrolysis. The crystal structure and microstructure of tungsten coatings were characterized by X-ray diffractometry, scanning Electron microscopy, and energy X-ray dispersive analysis techniques. The results indicated that pulsed current density and duty cycle significantly influence tungsten nucleation and Electro-Crystallization phenomena. The average grain size of the coating becomes much larger with increasing cathodic current density, which demonstrates that appropriate high cathodic current density can accelerate the growth of grains on the surface of the substrate. The micro-hardness of tungsten coatings increases with the increasing thickness of coatings; the maximum micro-hardness is 482 HV. The prepared tungsten coatings have a smooth surface, a porosity of less than 1%, and an oxygen content of 0.024 wt%.
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The effects of Electro-deposition current parameters on performance of tungsten coating
International Journal of Refractory Metals and Hard Materials, 2012Co-Authors: Yanhong Liu, Yingchun Zhang, Qizong Liu, Fan JiangAbstract:Abstract Tungsten coatings prepared on heat sink materials (Al 2 O 3 –Cu) as PFC not only can release amount of impinging thermal power but also can resist erosion under plasma particles bombardment in the ITER reactor. Therefore Electro-deposition technique using for obtaining tungsten coating on Al 2 O 3 –Cu substrate was a novel technique especially for fusion applications. In this paper, pure tungsten coatings were successfully deposited under various pulsed current densities at 1173 K in Na 2 WO 4 –WO 3 melts. Furthermore pulse current density, duty cycle and period were investigated respectively so as to obtain well defined structures for tungsten coatings. The composition, crystal structure and microstructure of tungsten coatings were characterized by XPS, SEM and XRD techniques. The results indicated that pulsed current density, duty cycle and period have significant influence on tungsten nucleation and Electro-Crystallization phenomena.
Soroor Ghaziof - One of the best experts on this subject based on the ideXlab platform.
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Electrochemical studies of sol-enhanced Zn–Ni–Al2O3 composite and Zn–Ni alloy coatings
Journal of Electroanalytical Chemistry, 2015Co-Authors: Soroor Ghaziof, Paul A. Kilmartin, Wei GaoAbstract:Abstract Zn–Ni–Al 2 O 3 nano-composite coatings were Electrodeposited on mild steel using a novel sol enhanced Electroplating method. The effect of alumina sol on the Electrodeposition process, and coating properties was investigated using cyclic voltammetry, chronoamperometry and Electrochemical impedance spectroscopy. The results indicated that the Electro-Crystallization processes of Zn–Ni and Zn–Ni–Al 2 O 3 were governed by a three-dimensional nucleation process controlled by diffusion. Evaluation of nucleation mode in the presence and absence of alumina sol showed that the progressive nucleation was predominant for the Zn–Ni alloy deposit. However, for the Zn–Ni composite coating, the nucleation mode was closer to instantaneous nucleation. Nucleation parameters such as density of active nucleation sites and nucleation rate were increased in the presence of alumina nano-particles in the bath. Zn–Ni–Al 2 O 3 nano composite coatings produced more uniform and compact deposits, with fine grained microstructure when compared to Zn–Ni coatings. XRD results showed that the phase structure of both alloy and composite coatings was single Ni 5 Zn 21 -γ phase, and that the incorporation of alumina in the Zn–Ni coating refined the crystal grain size.
Yanhong Liu - One of the best experts on this subject based on the ideXlab platform.
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Electrodeposition of metallic tungsten coating from binary oxide molten salt on low activation steel substrate
Journal of Nuclear Materials, 2013Co-Authors: Yanhong Liu, Yingchun Zhang, Fan Jiang, Ningbo SunAbstract:Abstract Tungsten is considered a promising plasma facing armor material for future fusion devices. An Electrodeposited metallic tungsten coating from Na 2 WO 4 –WO 3 binary oxide molten salt on low activation steel (LAS) substrate was investigated in this paper. Tungsten coatings were deposited under various pulsed currents conditions at 1173 K in atmosphere. Cathodic current density and pulsed duty cycle were investigated for pulsed current Electrolysis. The crystal structure and microstructure of tungsten coatings were characterized by X-ray diffractometry, scanning Electron microscopy, and energy X-ray dispersive analysis techniques. The results indicated that pulsed current density and duty cycle significantly influence tungsten nucleation and Electro-Crystallization phenomena. The average grain size of the coating becomes much larger with increasing cathodic current density, which demonstrates that appropriate high cathodic current density can accelerate the growth of grains on the surface of the substrate. The micro-hardness of tungsten coatings increases with the increasing thickness of coatings; the maximum micro-hardness is 482 HV. The prepared tungsten coatings have a smooth surface, a porosity of less than 1%, and an oxygen content of 0.024 wt%.
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Electro-deposition tangsten coating on low activation steel substrates from Na2WO4-ZnO-WO3 melt salt
Rare Metals, 2012Co-Authors: Yanhong Liu, Yingchun Zhang, Qizong LiuAbstract:Tungsten coating is considered as a promising alternative material for plasma facing materials (PFC) in future fusion devices. The Electro-deposition of tungsten in Na2WO4-ZnO-WO3 melt at 1173 K on low activation steel substrates was studied in this work. Adherent and smooth tungsten films were deposited under various pulsed current conditions. The crystal structure and microstructure of tungsten deposits were characterized by XRD, SEM and EDX techniques. The results show that pulsed current density and duty cycle have a significant influence on tungsten nucleation and Electro-Crystallization phenomena. Uniform and smooth tungsten coating with high purity and high adherence is obtained on low active steel substrates as cathodic current density ranges from 35 to 25 mA·cm−2.
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The effects of Electro-deposition current parameters on performance of tungsten coating
International Journal of Refractory Metals and Hard Materials, 2012Co-Authors: Yanhong Liu, Yingchun Zhang, Qizong Liu, Fan JiangAbstract:Abstract Tungsten coatings prepared on heat sink materials (Al 2 O 3 –Cu) as PFC not only can release amount of impinging thermal power but also can resist erosion under plasma particles bombardment in the ITER reactor. Therefore Electro-deposition technique using for obtaining tungsten coating on Al 2 O 3 –Cu substrate was a novel technique especially for fusion applications. In this paper, pure tungsten coatings were successfully deposited under various pulsed current densities at 1173 K in Na 2 WO 4 –WO 3 melts. Furthermore pulse current density, duty cycle and period were investigated respectively so as to obtain well defined structures for tungsten coatings. The composition, crystal structure and microstructure of tungsten coatings were characterized by XPS, SEM and XRD techniques. The results indicated that pulsed current density, duty cycle and period have significant influence on tungsten nucleation and Electro-Crystallization phenomena.