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Povezivanje dva ili više različitih sastojaka u jednu supstancu daje gotovo beskrajne mogućnosti za stvaranje novih inženjerskih materijala. Ovi materijali, koji se zovu kompozitni materijali, mogu se karakterizovati nizom različitih osobina, stoga ova čuda inženjerstva se široko koriste u skoro svim oblastima industrije i nauke, posebno u automobilskoj, električnoj i elektronskoj, vazduhoplovnoj, građevinskoj i mašinskoj industriji, sportu i razonodi itd. Primena kompozitnih materijala je svestrana i u svim sferama industrije i života, te se elektroprovodni kompoziti koriste u industriji računara i elektronskih komponenti, elektroopremi, avioindustriji, kao hladni varovi. Ovi materijali se koriste i kao prekidači, elektromagnetni štitovi, kao zaštita od strujnog i naponskog udara, provodni lepkovi, u građevinarstvu., kao elektrode za solarne ćelije na bazi boja. Oni su takođe našli tehnološku primenu kao grejači sa samoregulatorima, elektronski i hemijski nosevi i senzori, fototermički optički snimači, kao adsorbensi i hemijski i elektrohemijski katalizatori, i u novije vreme u uređajima za skladištenje i konverziju električne energije. Elektroprovodni polimerni kompoziti imaju nekoliko prednosti u odnosu na svoje polazne gradivne supstance, a te prednosti uklјučuju manje troškove i lakoću proizvodnje, manju težinu, visoku fleksibilnost, veću apsorpcionu moć kada su u pitanju mehanički udari i mehanička naprezanja, imaju povećanu otpornost prema koroziji i izrazitu kontrolu provodnosti. U ovoj doktrorskoj disertaciji su prikazani eksperimentalni rezultati istraživanja svojstava kompozitnih materijala na bazi poli(metil metakrilatne) - PMMA, poli(laktidne)-PLA i poli(hidroksi butiratne)-PHB matrice punjenih elektrolitičkim bakarnim prahom. Udeо metalnog punioca, odnosno elektrolitički dobijenog bakarnog praha u ispitivanim kompozitnim uzorcima variran je u opsegu od 0.5-8.8 vol. %, a uzorci su pripremljeni u molderu na povišenim temperaturama. U eksperimentalnom del, Connecting two or more different ingredients into one substance gives almost endless possibilities for creating new engineering materials. These materials, which are called composite materials, can be characterized by a variety of different properties, and, therefore these engineering wonders are widely used in almost all areas of industry and science. In particular, these materials are widely used in automotive industry, electrical and electronic industry, aerospace, civil construction and mechanical engineering, sports and leisure, etc. Composites with metal fillers have found their use as electromagnetic protection of computers and electronic equipment, conductive adhesives for electronic equipment, cold welds, switches, devices for removal of static electricity, voltage protection devices, in dye based solar cells. They also found technological applications in self-regulating heaters, as photothermic optical recorders, chemical sensors and electronic noses, chemical and electrochemical catalysts and adsorbents, supercapacitors. The electroconductive polymer composites have several advantages over their constituents, and these advantages include lower costs and ease of production, high flexibility, lower weight-to-price ratio, greater ability to absorb mechanical impacts, corrosion resistance and conductivity control. The experimental results of the properties’ investigations of composite materials based on poly (methyl methacrylate) - PMMA, poly (lactide) - PLA and poly (hydroxybutyrate) - PHB matrices filled with electrolytic copper powder are shown in this thesisr. The volume fraction of metal filler in investigated composite materials was varied in the range of 0.5-8.8 vol. %, and the samples were prepared in laboratory molder at elevated temperatures. Various experimental methods and techniques were used in the experimental part for the analysis and characterization methods and tecniques were performed on the starting constituents and investigated composites

New biopolymers’ materials, suitable for the adsorption of noble metal ions, were synthesized by chemical and electrochemical modification of biopolymers. Optimization of cellulose acrylate synthesis by reaction with sodium cellulosate and acryloyl chloride was carried out. Optimal conditions for conducting the synthesis reaction of cellulose acrylate were as follows: the molar ratio of cellulose/potassium-t-butoxide/acryloyl chloride was 1:3:10 and the optimal reaction time was 10 h. On the basis of elemental analysis with optimal conditions for conducting the reaction of cellulose acrylate, the percentage of substitution of glucose units in cellulose was Y = 80.7%, and the degree of substitution of cellulose acrylate of DS = 2.4 was determined. The grafting reaction of acrylate vinyl monomers onto cellulose in acetonitrile with azoisobutyronitrile initiator in a nitrogen atmosphere was performed, by mixing for 5 h at acetonitrile boiling temperature. Radical copolymerizations of synthesized cellulose acrylate and 4-vinylpyridine, 1-vinylimidazole, 1-vinyl-2-pyrrolidinone, 9-vinylcarbazole, cellulosepoly-4-vinylpyridine, cellulose-poly-1-vinylimidazole, cellulose-poly-1-vinyl-2-pyrrolidinone and cellulose-poly-9-vinylcarbazole were performed. Cellulose acrylate and cellulose grafted copolymers were confirmed by IR spectroscopy, based on elementary analysis and the characteristics of grafted copolymers of cellulose were determined. The mass share of grafted copolymers, X, the relationship of derivative parts/cellulose vinyl group, Z, and the degree of grafting copolymers of cellulose (mass%) were determined. The grafed copolymers of cellulose with 4-vinylpyridine and 1- vinylimidazole were reacted with methyl iodide and the corresponding 1 - methylpyridinium iodide and 3-methylimidazolium iodide copolymers of cellulose were obtained. Copolymers were transformed into new polymeric reagents, differing in anions (ClO4-, CF3COO-, NO3-, p-TsO-, BF4-, PF6-) by usage of di

The morphologies of copper dendritic forms obtained in both potentiostatic and galvanostatic regimes of electrolysis with various amounts of the electricity were analyzed by the scanning electron microscopy (SEM) technique. Irrespective of amount of passed electricity, 3D (three dimensional) pine-like dendrites with sharp tips were formed in the potentiostatic regime of electrolysis. On the other hand, the amount of passed electricity had a strong effect on the shape of the 3D pine-like dendrites formed in the galvanostatic regime of electrolysis. Dendrites with sharp tips were formed with smaller amount of passed electricity, while dendrites with globular tips were formed with larger amounts. The change in the shape of the galvanostatically synthesized 3D pine-like dendrites was explained by comparison with copper deposits obtained potentiostatically at overpotentials that corresponded to the final overpotentials during galvanostatic regime of electrolysis for the analyzed amounts of electricity. Based on the similarity of the obtained morphologies at the macro level, it was concluded that the overpotential plays a crucial role in the formation of the electrolytically synthesized dendrites and that the controlled conditions of electrolysis could represent a suitable way for a synthesis of spherical Cu particles by electrolysis.

The processes of lead and zinc electrodeposition from the very dilute electrolytes were compared by the analysis of polarization characteristics and by the scanning electron microscopic (SEM) analysis of the morphology of the deposits obtained in the galvanostatic regime of electrolysis. The exchange current densities for lead and zinc were estimated by comparison of experimentally obtained polarization curves with the simulated ones obtained for the different the exchange current density to the limiting diffusion current density ratios. Using this way for the estimation of the exchange current density, it is shown that the exchange current density for Pb was more than 1300 times higher than the one for Zn. In this way, it is confirmed that the Pb electrodeposition processes are considerably faster than the Zn electrodeposition processes. The difference in the rate of electrochemical processes was confirmed by a comparison of morphologies of lead and zinc deposits obtained at current densities which corresponded to 0.25 and 0.50 values of the limiting diffusion current densities.

Lead electrodeposition processes from basic (nitrate) and complex (acetate) electrolytes were mutually compared by scanning electron microscopy and X-ray diffraction investigation of the produced powder particles. The shape of dendritic particles strongly depended on the type of electrolyte. Dendrites composed of a stalk and weakly developed primary branches (the primary type) were predominantly formed from the basic electrolyte. Ramified dendrites composed of a stalk and of both primary and secondary branches (the secondary type) were mainly formed from the complex electrolyte. In both types of powder particles, Pb crystallites were predominantly oriented in the (111) plane. The formation of powder particles of different shapes with strong (111) preferred orientation is discussed and explained by consideration of the general characteristics of the growth of crystals in electrocrystallization processes.

The effect of different current regimes of electrolysis on the micro- and nanostructural characteristics of open porous structures was examined by the analysis of honeycomb-like copper electrodes obtained by constant galvanostatic (DC) electrodeposition and by regimes of pulsating (PC) and reversing (RC) current. An increase in the number of holes fowled by detached hydrogen bubbles, the decrease in wall width between holes and changes in surface morphology around holes from cauliflower-like agglomerates of copper grains to dendrites were observed in the following order: the DC, PC and RC regime. The hole size formed in the RC regime was smaller than the hole size formed in the DC and PC regimes. Analysis of the obtained structural characteristics showed that the specific surface area of the honeycomb-like electrodes was increased by the application of the PC and RC regimes in relation to the DC regime.

Lead electrodeposition processes from basic (nitrate) and complex (acetate) electrolytes were mutually compared by scanning electron microscopy and X-ray diffraction investigation of the produced powder particles. The shape of dendritic particles strongly depended on the type of electrolyte. Dendrites composed of a stalk and weakly developed primary branches (the primary type) were predominantly formed from the basic electrolyte. Ramified dendrites composed of a stalk and of both primary and secondary branches (the secondary type) were mainly formed from the complex electrolyte. In both types of powder particles, Pb crystallites were predominantly oriented in the (111) plane. The formation of powder particles of different shapes with strong (111) preferred orientation is discussed and explained by consideration of the general characteristics of the growth of crystals in electrocrystallization processes.

The electrochemical deposition by pulse current of Zn-Co alloy coatings on steel was examined, with the aim to find out whether pulse plating could produce alloys that could offer a better corrosion protection. The influence of on-time and the average current density on the cathodic current efficiency, coating morphology, surface roughness and corrosion stability in 3% NaCl was examined. At the same Ton/Toff ratio the current efficiency was insignificantly smaller for deposition at higher average current density. It was shown that, depending on the on-time, pulse plating could produce more homogenous alloy coatings with finer morphology, as compared to deposits obtained by direct current. The surface roughness was the greatest for Zn-Co alloy coatings deposited with direct current, as compared with alloy coatings deposited with pulse current, for both examined average current densities. It was also shown that Zn-Co alloy coatings deposited by pulse current could increase the corrosion stability of Zn-Co alloy coatings on steel. Namely, alloy coatings deposited with pulse current showed higher corrosion stability, as compared with alloy coatings deposited with direct current, for almost all examined cathodic times, Ton. Alloy coatings deposited at higher average current density showed greater corrosion stability as compared with coatings deposited by pulse current at smaller average current density. It was shown that deposits obtained with pulse current and cathodic time of 10 ms had the poorest corrosion stability, for both investigated average deposition current density. Among all investigated alloy coatings the highest corrosion stability was obtained for Zn-Co alloy coatings deposited with pulsed current at higher average current density (jav = 4 A dm-2)., Ispitivano je elektrohemijsko taloženje cink-kobalt legure pulsirajućom strujom na čeliku, a s ciljem dobijanja zaštitnih prevlaka sa povećanom korozionom stabilnošću. Prevlake legura su taložene pulsirajućim režimom sa različitim srednjim gustinama struje i pri različitom trajanju katodnog pulsa. Analiziran je uticaj ovih parametara na iskorišćenje struje prilikom elektrohemijskog taloženja na izgled prevlaka (snimanje elektronskim mikroskopom), hrapavost prevlaka i njihovu korozionu stabilnost u 3% NaCl (merenjem slobodnog korozionog potencijala u agensu korozije i snimanjem polarizacionih krivih). Pokazano je da u zavisnosti od vremena pulsa, prevlake taložene pulsirajućim režimom mogu da imaju bolju homogenost, sitnije aglomerate kristalnih zrna i manju hrapavost od onih taloženih pri istim uslovima, ali konstantnom gustinom struje. Veću korozionu stabilnost pokazale su prevlake legura taložene većom srednjom gustinom struje.

Morphologies of copper powder particles obtained by both potentiostatic and pulsating overpotential (PO) regimes of electrolysis were investigated by the technique of scanning electron microscopy (SEM). Particles of dendritic or cauliflower-like shape were formed in the dependence of the selected parameters of square-waves PO. The obtained particles were compared with those obtained in the constant potentiostatic regime from solutions of different CuSO4 and H2SO4 concentrations. It was shown that the effect of the decreasing deposition pulse was equivalent to the increasing CuSO4 concentration. Pause duration was equivalent to the used concentration of H2SO4, while the overpotential amplitude in the PO regime corresponded to the overpotential of electrodeposition in the constant potentiostatic mode. Morphologies of powdered deposits were grouped in the three hydrogen co-deposition ranges and their formation was discussed in the dependence of the quantity of hydrogen generated at the cathode surface during electrochemical deposition processes.

In this study the honeycomb-like copper structures electrodeposited by the regime of pulsating overpotential in the second range were analyzed by the technique of scanning electron microscopy. The overpotential amplitude of 1000 mV, deposition pulse of 1 s, and pause durations of 1, 5, 10 and 15 s were selected for the production of this type of structures. The size of holes which remained upon detachment of hydrogen bubbles do not depend on the length of pause duration. On the other hand, the change in morphology of electrodeposited copper around holes from cauliflower-like agglomerates of copper grains to degenerated dendrites is observed when pause duration was increased. Effects of the application of the regime of pulsating overpotential in the second range on the formation of the honeycomb-like structures were less pronounced than the effects attained by the application of the same regime in the millisecond range. However, they were more pronounced than those attained by electrodeposition in the regime of constant potential.

The morphology, phase and chemical composition of Ni-Co alloy powders electrodeposited from an ammonium sulfate-boric acid containing electrolyte with different ratio of Ni/Co ions were investigated. The ratios of NVCo ions were 1/1, 1/2 and 1/3. The morphology, chemical composition and phase composition of the electrodeposited alloy powders were investigated using AES, SEM, EDS and XRD analysis. Composition of the electrolyte, i.e. the ratio of Ni/Co concentrations was found to influence both, the alloy phase composition and the morphology of Ni-Co alloy powders. At the highest ratio of Ni/Co = 1/1 concentrations typical 2D fern-like dendritic particles were obtained. With a decrease of NVCo ions ratio among 2D fern-like dendrites, 3D dendrites and different agglomerates were obtained. X-ray diffraction studies showed that the alloy powders mainly consisted of the face-centered cubic alpha-nickel phase and hexagonal close-packed alpha-cobalt phase and minor proportions of face-centered cubic alpha-cobalt phase. The occurrence of the latter phase was observed only in the alloy powder with the higher cobalt concentration in electrolyte. The electrodeposition of Ni-Co powders occurred in an anomalous manner. (C) 2011 Elsevier Inc. All rights reserved.

The first successful attempt to electrodeposit Zn-Mn alloy coatings from alkaline bath was made only a few years ago. In this kind of solution, potassium pyrophosphate (K4P2O7) serves both as a complexing agent and as the basic electrolyte. The aim of this work was to study the electrodeposition process and properties of Zn-Mn alloy coatings deposited from pyrophosphate solution, with a new kind of alkaline pyrophosphate bath. Namely, chloride salts were used as the source of metal ions and ascorbic acid was used as reducing agent. The composition of the plating solution was as follows: 1 mol dm-3 K4P2O7 + 0.017 mol dm-3 ascorbic acid + 0.05 mol dm-3 ZnCl2 + 0.05 mol dm-3 MnCl2·4H2O. Cathodic processes during the alloy electrodeposition were investigated using linear voltammetry. The influence of addition of small amounts of ascorbic acid on the cathodic processes was established. It was shown that this substance inhibits hydrogen evolution and increases the current efficiency of alloy deposition. The current efficiency in the plating bath examined was in the range of 25 and 30%, which was quite higher as compared to the results reported in the literature for electrodeposition of Zn-Mn alloy from pyrophosphate bath. Electrodeposition of Zn-Mn alloys was performed galvanostatically on steel panels, at current densities of 20?120 mA cm-2. The coatings with the best appearance were obtained at current densities between 30 and 80 mA cm-2. The surface morphology studies, based on atomic force microscopy measurements, showed that morphology of the deposits is highly influenced by deposition current density. Zn-Mn coating deposited at 30 mA cm-2 was more compact and possessed more homogeneous structure (more uniform agglomeration size) than the coating deposited at 80 mA cm-2. Such dependence of morphology on the current density could be explained by the high rate of hydrogen evolution reaction during the electrodeposition process., U proteklih nekoliko godina pokazano je da se alkalni pirofosfatni elektrolit može primeniti za elektrohemijsko taloženje prevlaka Zn-Mn legura na čeliku. U ovom radu je ispitana zavisnost morfologije i hemijskog sastava Zn-Mn prevlaka od primenjene gustine struje taloženja. Karakterizacija prevlaka vršena je mikroskopijom atomskih sila i energetskom disperzionom atomskom analizom. Metodom linearne voltametrije ispitan je uticaj dodatka, askorbinske kiseline, na katodne procese. Utvrđeno je da se iz alkalnog rastvora mogu dobiti prevlake zadovoljavajućeg kvaliteta, ali da gustina struje ima veliki uticaj na homogenost i hrapavost površine Zn-Mn prevlaka. Askorbinska kiselina inhibira redukciju vodonika i povećava iskorišćenje struje za taloženje legure.