Electrodeposition of iron powder particles of different characteristics

Iron deposits obtained at high current densities and overpotentials are very important from a technological point of view. It has been stated that the open and porous structures of copper or iron deposits obtained at high current densities were ideally suited for use as electrodes in electrochemical devices such as fuel cells, batteries and chemical sensors, while the extremely high surface area is relevant for evaluating some electrochemical reactions. Mainly two types of electrolytes were investigated and these were based on sulfate and chloride electrolytes. With increasing duration of electrolysis, dendrites merge, which is unacceptable for the case of further application. These deposits must be grinded in order to obtain powders. However, in the range of lower acidity the deposits become powdery and, in some cases, may be spongy and sticky. Generally, up to now research indicates that electrodeposition of Fe powders have two steps, deposition of fragile film and grinding. It must be emphasized that we tried and succeeded to obtain Fe powders without grinding process. The aim of this work was to investigate electrodeposition processes of Fe powders from sulfate and chloride electrolytes and morphologies of powder as a function of type of electrolyte and current density.Belgrade, Serbia, June 6-10, 201

Electrodeposition of iron powder particles of different characteristics

Iron deposits obtained at high current densities and overpotentials are very important from a technological point of view. It has been stated that the open and porous structures of copper or iron deposits obtained at high current densities were ideally suited for use as electrodes in electrochemical devices such as fuel cells, batteries and chemical sensors, while the extremely high surface area is relevant for evaluating some electrochemical reactions. Mainly two types of electrolytes were investigated and these were based on sulfate and chloride electrolytes. With increasing duration of electrolysis, dendrites merge, which is unacceptable for the case of further application. These deposits must be grinded in order to obtain powders. However, in the range of lower acidity the deposits become powdery and, in some cases, may be spongy and sticky. Generally, up to now research indicates that electrodeposition of Fe powders have two steps, deposition of fragile film and grinding. It must be emphasized that we tried and succeeded to obtain Fe powders without grinding process. The aim of this work was to investigate electrodeposition processes of Fe powders from sulfate and chloride electrolytes and morphologies of powder as a function of type of electrolyte and current density.Belgrade, Serbia, June 6-10, 201

Electrodeposition of Fe Powder from Citrate Containing Electrolytes

Polarization characteristics of the electrodeposition processes of Fe powders from different citrate electrolytes and the morphology of the obtained powders were investigated. The effect of complexing agents on the cathodic polarization, the current efficiency and morphology of electrodeposited Fe powders were investigated. The morphology of obtained powders depends on the kind of supporting electrolyte, but not on the current density in investigated range. A characteristic feature of powders deposited from citrate-chloride supporting electrolyte is cauliflower-like compressed structure. On the other side, Fe powders electrodeposited from citrate-sulfate supporting electrolyte appeared in the form of spongy-like agglomerates. Possibility of Fe powders protection from corrosion in the process of production and during long-term storing has been shown

The Effect of Periodically Changing Regimes on the Electrodeposition of Silver Powder

The effect of different deposition regimes (constant and reversing currents, constant and pulsating overpotential), on the powdered and dendritic silver electrodeposits morphology were investigated. The morphology of electrodeposited silver powder was studied utilizing a scanning electron microscope. The results obtained in constant regimes were compared with those obtained in pulsating and reversing regimes. The size of dendrites decreased strongly with increased overpotential or current. It was also shown that the agglomeration of silver dendrites in spongy-like agglomerates was strongly decreased by pulsating overpotential electrodeposition or reversing current. The possibility of obtaininig powder particles, with different properties, depending on conditions of electrolysis was demonstrated

Synthesis and sintering of high-temperature composites based on mechanically activated fly ash

Amount of fly ash which is and yet to be generated in the coming years highlights the necessity of developing new methods of the recycling where this waste can be reused in significant quantity. A new possibility for fly ash utilization is in high-temperature application (thermal insulators or/and refractory material products). As such, fly ash has to adequately answer the mechanical and thermal stability criteria. One of the ways of achieving it is by applying mechanical activation procedure on fly ash. In present study, fly ashes from two different power plants were mechanically activated in a planetary ball mill. Mechanically treated fly ashes were cemented with two different binders: standard Portland cement and high-aluminates cement. Physico-chemical analysis and investigation of mineralogical components of composites are emphasized, due to the changes occurred in fly ash during mechanical activation and sintering of composites. Macro-performance of the composites was correlated to the microstructure of fly ash studied by means of XRD and SEM analysis. Thermal stability of crystalline phases was investigated with DTA. Highlight was placed on determination of relationship between mechanically activated fly ash and obtained composites microstructure on one side and behavior of sintered composites on the other side. [Projekat Ministarstva nauke Republike Srbije, br. 172057, 45008 and a project F-198, financed by Serbian Academy of Sciences and Arts

STRUCTURAL CHARACTERISTICS OF ELECTRODEPOSITED COPPER COATINGS

The samples of rolled copper were mechanically and electrochemically polished in suitable electrolytes for electrochemical polishing. These substrate surfaces that had been prepared in advance, served as the basis for depositing of copper layers from two baths, namely, from the basic electrolyte(OR) with the following composition: 240 g/dm3 CuSO4 ∙ 5 H2O + 60 g/dm3 H2SO4i as well as from the bath which contained brightening addition agents(OR +DS). STM and AFM techniques show in great detail the structural properties which determine whether the metal surfaceis are as bright as a mirrior or not, that is, whether the obtained topography of the surface is more or less rough. It was determined that a considerable increase of roughness occurred in the samples where copper layers were deposited from the basic sulfate bath (OR) when compared with mechanical, and mechanical-electrochemical samples. In addition, depositing of the samples from the bath with brightening addition agents (OR +DS) resulted in the decrease of surface roughness

Electrodeposition of Fe Powder from Citrate Containing Electrolytes

Polarization characteristics of the electrodeposition processes of Fe powders from different citrate electrolytes and the morphology of the obtained powders were investigated. The effect of complexing agents on the cathodic polarization, the current efficiency and morphology of electrodeposited Fe powders were investigated. The morphology of obtained powders depends on the kind of supporting electrolyte, but not on the current density in investigated range. A characteristic feature of powders deposited from citrate-chloride supporting electrolyte is cauliflower-like compressed structure. On the other side, Fe powders electrodeposited from citrate-sulfate supporting electrolyte appeared in the form of spongy-like agglomerates. Possibility of Fe powders protection from corrosion in the process of production and during long-term storing has been shown

The Effect of Periodically Changing Regimes on the Electrodeposition of Silver Powder

The effect of different deposition regimes (constant and reversing currents, constant and pulsating overpotential), on the powdered and dendritic silver electrodeposits morphology were investigated. The morphology of electrodeposited silver powder was studied utilizing a scanning electron microscope. The results obtained in constant regimes were compared with those obtained in pulsating and reversing regimes. The size of dendrites decreased strongly with increased overpotential or current. It was also shown that the agglomeration of silver dendrites in spongy-like agglomerates was strongly decreased by pulsating overpotential electrodeposition or reversing current. The possibility of obtaininig powder particles, with different properties, depending on conditions of electrolysis was demonstrated

Specifična absobcijska energija staklo-poliester kompozitne cijevi pod statičkim tlačnim opterećenjem

The experimental determination of energy of glass-polyester composite tubes static fracture is done. The tubes are of defined structure and known processes of fabrication. The aim was to determine the possibility of their usage as damping elements during impact. Two types of tubular samples with different diameters were tested until fracture under static (low speed) compressive loading. The applied forces and sample lengths were measured until complete destruction of samples. From the diagrams received directly from testing devices, certain energy values explained in the paper were determined.U radu je prikazano eksperimentalno određivanje statičke energije loma staklo-poliester kompozitnih cijevi poznate struktura materijala i postupka izrade. Cilj ispitivanja je bio odrediti mogućnost primjene ugradnje takvih cijevi u elemente za prigušivače udara. Pod djelovanjem spornog statičkog tlačnog opterećenja ispitivana su dva tipa cijevi različitih presjeka. Pri tom su mjerene primenjene sile i duljine uzoraka sve do potpunog loma cijevi. Na osnovu dobivenih dijagrama su izračunate vrijednosti specifičnih energija apsorpcije

Characterization and Morphology of Copper Powder Particles as a Function of Different Electrolytic Regimes

The effect different deposition regimes (constant and reversing currents), on the powdered copper electrodeposits morphology were investigated. The results obtained in constant regimes were compared with those obtained in reversing regimes. The morphology of electrodeposited copper powder were investigated using a scanning electron microscope (SEM). The effect of the current amplitude, cathodic-to-anodic time ratio and period of the current wave are discussed. It is shown that the parameters determining the reversing current wave determine the micromorphology of the copper powder particles deposited. On the other side, technological properties of powders depend on their granulometry and particle morphology. Very often one method is inadequate for characterization of the morphology of powder particles. This paper also studied different methods for clear describing of the copper powder granulometry and morphology