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In this work, silver/poly(vinyl alcohol), Ag/PVA, colloidal dispersions were obtained by electrochemical reduction of Ag+. The electrochemical synthesis of silver nanoparticles in aqueous solutions of 5 and 10 wt. % PVA, containing 0.1 M KNO3 and 3.9 mM AgNO3, was performed at a constant current density of 25 mA cm-2 for a synthesis time of 10 min. The presence of silver nanoparticles was confirmed by UV-Vis spectroscopy. Cyclic voltammetry analysis and FT-IR spectroscopy indicated interactions between the silver nanoparticles and the PVA molecules. TEM analysis confirmed the spherical shape of the obtained silver nanoparticles, with a mean diameter of 15±9 nm. ., U ovom radu pokazano je dobijanje koloidnih disperzija srebro/poli(vinil alkohol), Ag/PVA, elektrohemijskom redukcijom Ag+. Elektrohemijska sinteza nanočestica srebra u vodenim rastvorima poli(vinil alkohola) sa 5 i 10 mas. % PVA, koji su sadržali 0,1 M KNO3 i 3,9 mM AgNO3, vršena je pri konstantnoj gustini struje od 25 mA×cm-2 u trajanju od 10 min. Prisustvo nanočestica srebra potvrđeno je ultraljubičastom i vidljivom spektroskopijom. Cikličnom voltametrijom i infracrvenom spektroskopijom pokazana je interakcija između nanočestica srebra i molekula poli(vinil alkohola). Analizom transmisione elektronske mikroskopije je potvrđeno da su dobijene nanočestice srebra sfernog oblika, prečnika 15±9 nm. .

The production of nanocomposite alginate microbeads with electrochemically synthesized silver nanoparticles (AgNPs) based on the electrostatic extrusion technique was investigated with respect to their potentials for utilization in pharmaceutical and biomedical applications. It was shown that electrochemical synthesis of AgNPs results in the reduction of practically all the Ag+ present in the initial solution, yielding stable Ag/alginate colloid solutions that were demonstrated to be suitable for sterilization, manipulation, and electrostatic extrusion with retention of the AgNPs. The presence of AgNPs in the alginate colloid solutions had negligible effects on the size of the produced Ag/alginate microbeads, which was mainly determined by the electrostatic potential applied during the extrusion. On the other hand, the incorporation of AgNPs within the alginate hydrogel induced slight changes in biomechanical properties of the microbeads determined in a biomimetic bioreactor. Thus, packed beds of nanocomposite Ag/alginate microbeads exhibited a slightly higher dynamic compression modulus as compared to that of control alginate microbeads (154±4 and 141±2 kPa, respectively). On the other hand, the equilibrium unconfined compression modulus was significantly lower for the nanocomposite microbeads as compared to that of the controls (34±2 and 47±1 kPa, respectively)., U ovom radu je ispitivan proces dobijanja elektrostatičkom ekstruzijom nanokompozitnih alginatnih mikročestica sa inkorporisanim elektrohemijski sintetisanim nanočesticama srebra u pogledu potencijala za primenu u farmaciji i biomedicini. Pokazalo se da tokom elektrohemijske sinteze nanočestica dolazi do praktično potpune redukcije Ag jona prisutnih u početnom rastvoru, dajući na taj način stabilne Ag/alginatne koloidne rastvore. Pokazano je zatim, da su ovi rastvori pogodni za sterilizaciju, manipulaciju, kao i elektrostatičku ekstruziju uz zadržavanje i očuvanje nanočestica. Prisustvo nanočestica srebra u koloidnim rastvorima nije imalo uticaj na veličinu dobijenih Ag/alginatnih mikročestica koja je pretežno bila određena vrednošću primenjenog elektrostatičkog napona tokom ekstruzije. Sa druge strane, inkorporacija nanočestica srebra unutar alginatnog hidrogela je uzrokovala male promene biomehaničkih karakteristika koje su određene u biomimičnom bioreaktoru. Naime, modul elastičnosti pakovanih slojeva nanokompozitnih Ag/alginatnih mikro-čestica određen pri dinamičkoj kompresiji je bio nešto veći nego kod pakovanog sloja kontrolnih alginatnih mikročestica (154±4 i 141±2 kPa, redom) dok je ravnotežni modul elastičnosti slojeva nanokompozitnih mikročestica bio značajno manji (34±2 i 47±1 kPa, redom).

This paper presents a comprehensive method to evaluate a mixture of dicyclohexylamine and oleylamine (DCHA+OA) as a corrosion inhibitor for mild steel in a CO2 environment in the liquid and vapor phase. The volatile properties of the corrosion inhibitor were investigated in order to determine whether DCHA+OA could be used to control the severity of a top of the line (TLC) corrosion attack. Corrosion measurements were performed using electrochemical impedance spectroscopy, linear polarization resistance, potentio-dynamic sweep measurements, as well as electrical resistance and weight loss measurements, in order to determine the inhibitive performances of dicyclohexylamine and oleylamine. In order to define the surface morphological characteristics, the scanning electron microscopy technique was applied. The electrochemical study and the weight loss measurements indicated that DCHA+OA significantly decreased the corrosion rate in the liquid phase when 50 ppm of DCHA+OA was added. Scanning electron microphotographs indicated a protective inhibitor film was formed on the steel surface and revealed that good protection was achieved, together with a decrease in the corrosion rate, as determined by weight loss and electrochemical techniques. It was shown using electrical resistance measurements in the vapor phase, that a concentration of 1000 ppm DCHA+OA significantly decreased the corrosion rate at the top of the line only when it was carried there within its own foam and not due its volatility., U ovom radu ispitivana je zaštita niskougljeničnog čelika od korozije pod dejstvom CO2 primenom smese dicikloheksilamina i oleilamina (DCHA+OA) kao inhibitora u tečnoj i gasovitoj fazi. Isparljivost smese DCHA+OA je ispitivana u cilju potencijalne primene DCHA+OA kao lako isparljivog inhibitora za smanjenje brzine korozije u uslovima kondenzacije. Pri ispitivanju inhibitorskih svojstava smese diciklohekcilamina i oleilamina primenjene su sledeće tehnike karakterizacije: spektroskopija elektrohemijske impedancije, metoda linearne polarizacione otpornosti, metoda polarizacije linearno promenljivim potencijalom, merenje električne otpornosti, gravimetrijska metoda određivanja gubitka mase, kao i skenirajuća elektronska mikroskopija. Rezultati elektrohemijskih merenja i gravimetrijske metode određivanja gubitka mase pokazuju da dodata smesa DCHA+OA u koncentraciji od 50 ppm značajno smanjuje brzinu korozije u tečnoj fazi u odnosu na sistem bez inhibitora. Mikrofotografije površine čelika potvrđuju da se u prisustvu smese DCHA+OA smanjuje stepen korozije kao posledica formiranja zaštitnog filma inhibitora na površini niskougljeničnog čelika. Primenom tehnike merenja električne otpornosti u gasovitoj fazi pokazano je da dodatak smese inhibitora DCHA+OA u koncentraciji od 1000 ppm dovodi do značajnog smanjenja brzine korozije u uslovima kondenzacije, samo u slučaju kada se transport inhibitora do površine čelika ostvaruje u obliku pene, a ne zbog isparljivosti samog inhibitora.

The electrochemical characteristics of Ti0.6Ir0.4O2/Ti and Ti0.6Ru0.4O2/Ti anodes prepared by the sol-gel procedure from the corresponding oxide sols, obtained by force hydrolysis of the corresponding metal chlorides, were compared. The voltammetric properties in H2SO4 solution indicate that Ti0.6Ir0.4O2/Ti has more pronounced pseudocapacitive characteristics, caused by proton-assisted, solid state surface redox transitions of the oxide. At potentials negative to 0.0 VSCE, this electrode is of poor conductivity and activity, while the voltammetric behavior of the Ti0.6Ru0.4O2/Ti electrode is governed by proton injection/ejection into the oxide structure. The Ti0.6Ir0.4O2/Ti electrode had a higher electrocatalytical activity for oxygen evolution, while the investigated anodes were of similar activity for chlorine evolution. The potential dependence of the impedance characteristics showed that the Ti0.6Ru0.4O2/ /Ti electrode behaved like a capacitor over a wider potential range than the Ti0.6Ir0.4O2/Ti electrode, with fully-developed pseudocapacitive properties at potentials positive to 0.60 VSCE. However, the impedance characteristics of the Ti0.6Ir0.4O2/Ti electrode changed with increasing potential from resistor-like to capacitor-like behavior., U radu su ispitivane elektrohemijske karakteristike Ti0,6Ir0,4O2/Ti i Ti0,6Ru0,4O2/Ti anoda dobijenih sol-gel postupkom iz oksidnih solova sintetisanih forsiranom hidrolizom odgovarajućih hlorida metala. Voltametrijske karakteristike u rastvoru H2SO4 ukazuju na više izraženo pseudokapacitivno ponašanje Ti0,6Ir0,4O2/Ti elektrode koje je posledica površinskih redoks prelaza u čvrstom stanju uz učešće protona. Na potencijalima negativnijim od 0,0 VZKE ova elektroda pokazuje slabu provodnost i aktivnost, dok voltametrijskim ponašanjem Ti0,6Ru0,4O2/Ti elektrode dominira prodor protona u strukturu oksida. Ti0,6Ir0,4O2/Ti anoda je elektrokatalitički aktivnija za reakciju izdvajanja kiseonika, dok su anode sličnih aktivnosti za reakciju izdvajanja hlora. Impedansne karakteristike formiranih anoda pokazuju da se Ti0,6Ru0,4O2/Ti elektroda ponaša slično kondenzatoru u širem opsegu potencijala nego što je to slučaj sa Ti0,6Ir0,4O2/Ti elektrodom, sa potpuno razvijenim pseudokapacitivnim svojstvima na potencijalima pozitivnijim od 0,60 VZKE. S druge strane, za Ti0,6Ir0,4O2/Ti elektrodu se uočava prelaz sa karakteristika sličnih otporniku na karakteristike slične kondenzatoru sa porastom potencijala elektrode.

The photoelectrochemical properties of a sol-gel prepared titanium oxide coating applied onto a Ti substrate were investigated. The oxide coating was formed from an inorganic sol thermally treated in air at 350°C. The coating consisted of agglomerates of narrow size distribution around 100 nm. The photoelectrochemical characteristics were evaluated by investigating the changes in the open circuit potential, current transients and impedance characteristics of a Ti/TiO2 electrode upon illumination by UV light in H2SO4 solution and in the oxidation of benzyl alcohol. The electrode was found to be active for photoelectrochemical reactions in the investigated solutions., Fotoelektrohemijska svojstva titan-oksida dobijenog sol-gel portupkom ispitivana su na oksidnoj prevlaci nanetoj na titansku podlogu. Prevlaka je termički tretirana u vazduhu na temperaturi od 350°C. Prevlaka se sastoji od zrna ujednačene raspodele po veličini od oko 100 nm. Fotoelektrohemijske karakteristike ustanovljene su ispitivanjem promena potencijala otvorenog kola, vremenske zavisnosti struje i impedansnih karakteristika Ti/TiO2 elektrode pri osvetljenosti UV svetlošću u rastvoru H2SO4 i pri oksidaciji benzil-alkohola. Ustanovljena je fotoaktivnost elektrode u ispitivanim sistemima.

An aqueous boehmite sol was prepared by the peptization of Al(OH)3. The electrophoretic deposition of boehmite coatings on titanium from the aqueous sol was performed at a constant voltage (from 1.0 to 10 V) and for a constant deposition time (from 10 to 30 min). Increasing the applied voltage and deposition time increased the mass of the boehmite coating. It was shown that boehmite coatings of maximum thickness, low porosity and good adhesion can be formed at lower deposition voltages and longer deposition times. The boehmite powder, obtained by drying the prepared aqueous sol, and the boehmite coatings were thermally treated at 1000 °C and 1300 °C with a holding period of 1 h at the maximum temperature. X-Ray diffraction analysis of the thermally treated samples confirmed the existence of -Al2O3 and Al2O3 phases, respectively, while scanning electron microscopy revealed the graininess of the structure of the -Al2O3 coatings treated at 1300 °C, indicating a significantly lower sintering temperature of the boehmite coating obtained by electrophoretic deposition., Vodeni sol bemita je pripremljen peptizacijom Al(OH) 3 . Elektroforetsko taloženje prevlaka bemita iz vodenog sola vršeno je pri konstantnom naponu 1,0 do 10 V) i za konstantna vremena taloženja (10 do 30 min). Povećanje napona i produžavanje vremena taloženja dovodi do porasta mase prevlake. Pokazano je da se prevlake najveće debljine, male poroznosti i dobre adhezije mogu formirati na nižim naponima i pri dužim vremenima taloženja. Rezultati analize difrakcije X-zraka i skenirajuće elektronske mikroskopije su potvrdili da su sinterovanjem praha bemita i prevlake bemita na temperaturama od 1000 °C i 1300 °C dobijeni  -alumijum-oksid i  -aluminijum- oksid, respektivno. To ukazuje na značajno sniženje temperature sinterovanja praha bemita i homogene prevlake bemita dobijene elektroforetskim taloženjem iz sola.

One of the most important factors in corrosion prevention by protective coatings is the loss of coating adhesion under environmental influence. In this work, the adhesion of epoxy cataphoretic coatings was examined on steel and steel modified by Zn-Fe and Zn-Co alloys. The dry and wet adhesions of epoxy primers were measured by the direct pull-off standardized procedure, as well as indirectly by the NMP test. The corrosion stability of the coated samples was investigated by electrochemical impedance spectroscopy. It was shown that under dry testing conditions all the samples exhibited very good adhesion. However, different trends of adhesion loss of different protective systems during exposure to a corrosive agent (3 % NaCl solution) were observed. The lowest adhesion values were obtained for epoxy coating on the steel substrate. The change in adhesion of the epoxy coating on steel modified by Zn-Co alloy during immersion in 3 % NaCl solution for 24 days was the smallest of all the investigated samples. Electrochemical impedance measurements in 3 % NaCl solution confirmed the good protective properties of this protective system, i.e., greater values of pore resistance were obtained., Jedan od najvažnijih faktora u zaštiti od korozije organskim prevlakama je gubitak adhezije organskih prevlaka pod uticajem korozione sredine. U ovom radu proučavana je adhezija epoksidnih kataforetskih prevlaka na čeliku i čeliku modifikovanom legurama Zn-Fe i Zn-Co. Ispitivane su tzv. suva i mokra adhezija standardnim pull-off postupkom, kao i NMP testom. Koroziona stabilnost svih uzoraka je ispitivana spektroskopijom elektrohemijske impedancije. Svi uzorci su imali dobru početnu adheziju, međutim tokom delovanja korozionog agensa (3 % NaCl) promena adhezije se značajno razlikovala kod različitih zaštitnih sistema. Najmanje vrednosti adhezije su dobijene u slučaju epoksidne prevlake na čeliku. Ukupno smanjenje adhezije tokom 24 dana ispitivanja je najmanje za epoksidnu prevlaku na čeliku modifikovanom Zn-Co legurom. Najveće vrednosti otpornosti u porama epoksidne prevlake tokom celokupnog ispitivanog perioda delovanja korozionog agensa kod prevlake na čeliku modifikovanom Zn-Co legurom takođe ukazuju na veliku stabilnost ovog zaštitnog sistema.

Titanium anodes with an active RuO2 coating of two different thicknesses were prepared from the oxide suspended in ethanol ("ink" method), while the oxide itself was synthesized by the hydrolysis of ruthenium ethoxide in an ethanolic solution (alkoxide route). The morphology of prepared oxide was examined by scanning electron microscopy. The electrochemical properties of the prepared Ti/RuO2 anodes, involving their cyclic voltammetric behavior in H2SO4 and NaCl solutions, activity in the chlorine and oxygen evolution reaction, impedance behavior in H2SO4, and stability during electrolysis in dilute chloride solutions, were investigated. The performances of the anodes are compared to those of a Ti/RuO2 anode prepared by the sol-gel procedure from an oxide sol obtained by the forced hydrolysis of ruthenium chloride in acid solution. The anodes prepared via the alkoxide route showed a higher capacitance and activity for the chlorine evolution reaction than the anode prepared by the inorganic sol-gel procedure. The results of the stability test showed that the utilization of the coating active material is better when the anodes were prepared via the alkoxide route than via the inorganic sol-gel procedure, particularly for anodes with a smaller mass of coating. The different rates of loss of activity indicate a degradation mechanism for the anodes prepared via the alkoxide route in which electrochemical dissolution of RuO2 from the coating surface prevails over the growth of an insulating TiO2 layer in the coating/Ti substrate interphase. The effect of RuO2 dissolution from the coating surface increases with increasing coating mass., Titanske anode sa aktivnom prevlakom od oksida rutenijuma dve različite debljine, formirane su od oksida dobijenog hidrolizom rutenijum(III)-etoksida u etanolskom rastvoru ("ink" metoda). Morfologija dobijenog oksida ispitivana je skenirajućom elektronskom mikroskopijom. Ispitivana su elektrohemijska svojstva formiranih anoda, koja podrazumevaju ciklično-voltametrijsko ponašanje u rastvorima H 2SO4 i NaCl, aktivnost u reakcijama izdvajanja hlora i kiseonika, impedansno pona- šanje i stabilnost tokom elektrolize razblaženih rastvora hlorida. Karakteristike dobijenih anoda upoređene su sa karakteristikama anode formirane sol-gel postupkom iz oksidnog sola dobijenog forsiranom hidrolizom rutenijum(III)-hlorida u kiseloj sredini (5 mol dm-3HCl). Anode formirane alkoksidnim postupkom imaju veću kapacitivnost i aktivnost za reakciju izdvajanja hlora od anode dobijene sol-gel postupkom iz neorganskog sola. Rezultati testa stabilnosti u rastvoru hlorida pokazuju da je iskorišćenje aktivnog materijala prevlake takođe bolje kod anoda dobijenih alkoksidnim postupkom, naročito za anodu sa manjom debljinom prevlake. Rezultati ukazuju na to da u mehanizmu gubitka aktivnosti anoda dobijenih alkoksidnim postupkom elektrohemijsko rastvaranje oksida rutenijuma sa površine prevlake preovlađuje u odnosu na rast izolatorskog sloja oksida titana u međufazi prevlaka/ titanska podloga. Efekt rastvaranja RuO2 sa površine je izraženiji kod prevlake veće debljine.

Zn–Fe alloy electrochemically deposited on steel under various deposition conditions were investigated using anodic linear sweep voltammetry (ALSV) and X-ray diffraction (XRD) analysis for phase structure determination, energy dispersive X-ray (EDX) analysis for determination of chemical composition and polarization measurements and open circuit potential measurements for determination of corrosion properties. The influence of deposition current density on the chemical composition, phase structure and corrosion stability of Zn–Fe alloys was studied. It was shown that deposition current density strongly affects the corrosion stability of Zn–Fe alloys, while Zn–Fe alloy electrodeposited at 4Adm-2 exhibited the lowest corrosion rate., Legure Zn–Fe elektrohemijski taložene na čeliku pod različitim uslovima ispitivane su primenom anodne linearne promene potencijala i difrakcije X-zraka, za određivanje fazne strukture, spektroskopije energetski dispergovanih X-zraka, za određivanje hemijskog sastava i polarizacionih merenja kao i merenja potencijala otvorenog kola, za određivanje korozione stabilnosti. Proučavan je uticaj gustine struje taloženja na hemijski sastav fazne strukture i korozionu stabilnost Zn–Fe legura. Pokazano je da gustina struje taloženja veoma utiče na korozionu stabilnost Zn–Fe legura, i da legura taložena gustinom struje od 4 Adm-2 ima najmanju brzinu korozije.

The influence of the deposition parameters on the porosity of thin alumina films electrophoretically deposited on steel from aqueous suspensions was investigated. The effects of the applied voltage, deposition time, suspension temperature and the solid content of the aqueous suspension on the porosity of the obtained alumina films have been determined using optical microscopy coupled with image analysis. It was shown that the lowest film porosity was obtained from a suspension containing 20 wt.% alumina powder at the lowest applied voltage (30 V), for a longer deposition time (10 min) using a suspension temperature of 30 ºC. This behavior can be explained by the smaller amount of hydrogen evolved on the cathode during the electrophoretic deposition process., Ispitivan je uticaj parametara taloženja, i to napona taloženja, vremena talo ženja, temperature suspenzije i koncentracije čvrste faze u suspenziji, na poroznost kataforetski taloženih tankih filmova iz vodene suspenzije praha aluminijum-oksida na čeliku.Poroznost dobijenih filmova određivana je primenom metode optičke mikroskopije uz analizu slike. Na osnovu dobijenih rezultata pokazano je da je najmanja poroznost prevlake aluminijum-oksida na čeliku dobijena pri taloženju iz vodene suspenzije koncentracije 20 mas%, pri naponu taloženja 30 V, za vreme taloženja 10 minuta i pri temperaturi suspenzije 30 °C.Ovakvo ponašanje moguće je objasniti manjom količinom izdvojenog vodonika na katodi tokom elektroforetskog taloženja.

In order to understand the role of TiO2 in the deactivation mechanism of an active RuO2–TiO2 coating, an additional TiO2 layer was introduced in the support coating interphase of regular Ti//[RuO2–TiO2 anode in one case and on the surface of the coating in the other. The electrochemical behavior of these, with TiO2 enriched, anodes was compared with the behavior of anodes with regular RuO2–TiO2 coatings, which were subjected to an accelerated stability test. A high-frequency semicircle in the complex plane plot obtained by electrochemical impedance spectroscopy, for a regular RuO2–TiO2 coating corresponds to TiO2 enrichment in the coating as a consequence of anode corrosion. In the case of the coatings with additional TiO2 layers, a high-frequency semicircle was not observed. The additional TiO2 layers increase the coating overall resistance and influence the coating impedance behavior at low frequencies. Similar equivalent electrical circuits were used to analyze the impedance behavior of coatings having an additional TiO2 layer at different position within RuO2–TiO2 coating., U cilju ispitivanja uloge titan-oksida u deaktivaciji RuO2–TiO2 prevlake na titanskoj podlozi, ispitivane su osobine anoda sa dodatnim slojem TiO2 u međufazi podloga prevlaka, odnosno na površini prevlake. Elektrohemijsko ponašanje ovih upoređeno je sa ponašanjem anoda sa uobičajenom RuO2–TiO2 prevlakom, kao i sa onima koje su bile podvrgnute ubrzanom testu stabilnosti. Pojava polukruga u visoko-frekventnoj oblasti u dijagramima u kompleksnoj ravni, koja je registrovana spektroskopijom elektrohemijske impedancije za uobičajene RuO2–TiO2 prevlake, a koja je posledica obogaćivanja prevlake sa TiO2 tokom njene deaktivacije, nije uočena kod anoda sa dodatim TiO2 slojem. Dodati TiO2 slojevi povećavaju omsku otpornost prevlake i utiču na impedancijsko ponašanje pri niskim frekvencijama. Za analizu impedancijskog ponašanja prevlaka sa dodatim TiO2 slojevima kao i uobičajenih RuO2–TiO2 prevlaka koje su deaktivirane korišćena su slična ekvivalentna električna kola.

The model of organic film growth on a cathode during electrodeposition process proposes the current density-time and film thickness-time relationships and enables the evaluation of the rate contents for the electrochemical reaction of OH– ion evolution and for the chemical reaction of organic film deposition. The dependencies of film thickness and rate constants on the applied voltage, bath temperature and resin concentration in the electrodeposition bath have also been obtained. The deposition parameters have a great effect on the cathodic electrodeposition process and on the protective properties of the obtained electrodeposited coatings. From the time dependencies of the pore resistance, coating capacitance and relative permittivity, obtained from impedance measurements, the effect of applied voltage, bath temperature and resin concentration on the protective properties of electrodeposited coatings has been shown. Using electrochemical impedance spectroscopy, thermogravimetric analysis gravimetric liquid sorption experiments, differential scanning calorimetry and optical miscroscopy, the corrosion stability of epoxy coatings was investigated. A mechanism for the penetration of electrolyte through an organic coating has been suggested and the shape and dimensions of the conducting macropores have been determined. It was shown that conduction through a coating depends only on the conduction through the macropores although the quantity of electrolyte in the micropores of the polymer net is about one order of magnitude greater than that inside the conducting macropores., Pretpostavljeni matematički model rasta epoksidne kataforetske prevlake, koji daje zavisnost gustine struje od vremena taloženja i debljine prevlake od vremena taloženja, pokazuje dobro slaganje sa eksperimentalnim rezultatima i omogućava da se odrede vrednosti konstante brzine elektrohemijske reakcije stvaranja hidroksilnih jona i konstante brzine hemijske reakcije taloženja prevlake. Na osnovu toga su izvedene zavisnosti debljine prevlake i konstanti brzina procesa kataforetskog taloženja od napona, temperature i koncentracije polimera u rastvoru i pokazan uticaj ovih parametara na njih. Zaštitna svojstva kataforetskih prevlaka u velikoj meri zavise od uslova taloženja. Na osnovu vremenskih zavisnosti otpornosti elektrolita u porama prevlake kapacitivnosti i relativne permitivnosti prevlake određenih iz impedansnih merenja, pokazan je uticaj napona taloženja, temperature i koncentracije polimera u rastvoru na njena zaštitna svojstva. Na osnovu rezultata dobijenih iz spektroskopije elektrohemijske impedancije, termogravimetrijske analize diferencijalne skenirajuće kalorimetrije, sorpcionih merenja i optičke mikroskopije, ispitivana je koroziona stabilnost polimernih prevlaka i pretpostavljen je mehanizam prodiranja elektrolita kroz njih. Takođe su određeni oblik i dimenzije provodnih makropora i izračunat je sadržaj elektrolita u prevlaci. Provođenje kroz mikropore polimerne mreže je zanemarljivo u odnosu na provođenje kroz makropore iako je količina elektrolita u njima za red veličine veća u odnosu na količinu elektrolita u makroporama.

The corrosion behavior of epoxy coatings electrodeposited on aluminum, as well as on electrochemically and chemically modified aluminum were investigated during exposure to 3 % NaCl. Electrochemical impedance spectroscopy (EIS) and thermogravimetric analysis (TGA) were used for the determination of the protective properties of epoxy coatings on aluminum, anodized aluminum, phosphatized and chromatized-phosphatized aluminum. The protective properties of epoxy coatings on anodized and chromatized-phosphatized aluminum are significantly improved with respect to the same epoxy coatings on aluminum and phosphatized aluminum: higher values of the pore resistance and charge-transfer resistance, lower values of the coating capacitance, double-layer capacitance and relative permittivity (from EIS) smaller amount of absorbed water inside the coating (From TGA). On the other hand, the lower values of the ipdt temperature indicate a lower thermal stability of the epoxy coatings on anodized and chromatized-phosphatized aluminum., Proučavano je koroziono ponašanje epoksidnih prevlaka dobijenih kataforetskim taloženjem na aluminijumu i elektrohemijski i hemijski modifikovanom aluminijumu tokom delovanja 3 % rastvora NaCl. Za određivanje zaštitnih osobina epoksidnih prevlaka na aluminijumu, anodiziranom aluminijumu, fosfatiranom i hromatno-fosfatiranom aluminijumu korišćene su metode spektroskopije elektrohemijske impedancije i termogravimetrijske analize. Zaštitne osobine epoksidnih prevlaka na anodiziranom i hromatno-fosfatiranom aluminijumu su značajno poboljšane u odnosu na iste epoksidne prevlake na aluminijumu i fosfatiranom aluminijumu: veće vrednosti otpornosti u porama prevlake i otpornosti prenosa naelektrisanja na graničnoj površini metal-elektrolit i manje vrednosti kapacitivnost prevlake, kapacitivnosti električnog dvojnog sloja i relativne permitivnosti prevlake (impedansna merenja) i manja količina absorbovane vode u prevlaci (termogravimetrijska analiza). S druge strane, manje vrednosti ipdt temperature ukazuju na manju termičku stabilnost epoksidnih prevlaka na anodiziranom i hromatno-fosfatiranom aluminijumu.

The electrochemical and transport properties, as well as the thermal stability of epoxy coatings electrodeposited on steel and steel modified by Zn-Ni alloys were investigated during exposure to 3 % NaCl. The Zn-Ni alloys were electrodeposited on steel using direct and pulse current. From the time dependence of the pore resistance of the epoxy coating (impedance measurements), the diffusion coefficient of water through the epoxy coating (gravimetric liquid sorption measurements) and the thermal stability of the epoxy coating (thermogravimetric analysis), it was shown that Zn-Ni sublayers significantly improve the corrosion stability of a protective system based on an epoxy coating. The values of the pore resistance were almost unchanged over a long period of immersion time for epoxy coatings on steel modified by Zn-Ni alloys, inidicating the great stability of these protective systems. ., Proučavane su elektrohemijske i transportne karakteristike i termička stabilnost epoksidnih elektroforetskih prevlaka na čeliku i čeliku modifikovanom Zn-Ni legurama tokom delovanja 3 % rastvora NaCl. Legure Zn-Ni su taložene na čeliku konstantnom i pulsirajućom strujom. Na osnovu vremenske zavisnosti otpornosti u porama epoksidne prevlake (impedansna merenja), koeficijenta difuzije vode kroz epoksidnu prevlaku (gravimetrijsko određivanje sorpcionih karakteristika) i njene termičke stabilnosti (termogravimetrijska analiza), pokazano je da Zn-Ni podslojevi značajno povećavaju korozionu stabilnost zaštitnog sistema na bazi epoksidne prevlake. Skoro nepromenjene vrednosti otpornosti u porama tokom dugog perioda delovanja korozionog agensa kod epoksidnih prevlaka na čeliku modifikovanom Zn-Ni legurama ukazuju na veliku stabilnost ovih zaštitnih sistema. .

Protective polyester coatings on phosphatized steel were obtained with different combinations of diols (2-butyl-2-ethyl-1,3-propanediol or 2,2-dimethyl-1,3-propanediol), organic acids (1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, hexahydrophthalic acid anhydride or adipic acid) and hexamethoxymethylmelamine as a crosslinking agent. The acid resistance and corrosion stability of these coatings were investigated during exposure to different corrosive agents (30% H2SO4, 3% NaCl) using the acid resistance test, electrochemical impedance spectroscopy (EIS) and measurement of the film thickness, gloss and hardness. It was shown that coatings based on polyesters with more branched structures of the diol (2-butyl-2-ethyl-1,3-propanediol) and of the organic acid (hexahydrophthalic acid anhydride), which enable better crosslinking, exhibit better acid resistance and corrosion stability. Coatings with the optimal polyester/melamine ratio, which is close to the theoretical ratio for complete crosslinking, also show better protective properties.

Coil coated stainless steel is a new material for applications in civil and industrial fields with the purpose of reducing maintenance costs and increasing the service life of the products. The corrosion behaviour of different types of stainless steel coated with both polyester and fluoropolymer films of different thickness has been studied by means of AC impedance spectroscopy (EIS), the break-point frequency method and scanning electron microscopy analysis (SEM). The charge-transfer resistance and double-layer capacitance for both polyester and fluoropolymer coatings on stainless steel reveal no reactivity, corrosion or disbonding on the substrate. The changes of pore resistance, coating capacitance and break-point frequency over time indicate the different corrosion behaviour of polyester and fluoropolymer coatings due to their different chemical structure and film thickness. On the other hand, the polyester coatings on phosphatized galvanized steel exhibit quite different behaviour in regard to the same coatings on stainless steel. Different types of stainless steel as substrate cause the different corrosion behaviour of the investigated polyester and fluoro-polymer coatings. It has been observed that stainless steel which contains more nickel and molybdenum shows higher resistance to corrosion attack in chloride environments.