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Due to their wide range of colour pigments and uniform colouring, synthetic dyes currently dominate the market with a production of 8×10 5 tonnes per year [1]. Synthetic dyes are used in various industries such as textile, food processing, pharmaceutical, cosmetic, pulp and paper, etc., resulting in a large amount of wastewater contaminated with dye residues. Due to their complex structure, which makes them very stable and difficult to degrade, they have a negative impact on water quality. Their presence in surface waters causes them to block light transmission, impair photosynthesis of plants and algae in water, and reduce dissolved oxygen in water [2]. Some studies have shown that synthetic dyes contribute to carcinogenicity and mutagenicity in various species [3, 4]. Therefore, much attention is paid to the methods for their removal. In this study, electrocoagulation (EC) was used as an alternative method to remove crystal violet dye using AA2007 aluminium alloy electrodes. The simulated wastewater solution consisted of 4 mg/L crystal violet dye with the addition of 2 g/L NaCl as a supporting electrolyte. The pH of the electrolyte was adjusted to 3.2, 5.5 and 7.0, and the experiments were performed with current densities of 16, 24, and 32 mA/cm2 . The results showed that this method can be successfully used for the treatment of wastewater contaminated with dyes reaching more than 98% of removal efficiency after 50 min of treatment with the highest current density applied. References: [1] G.F. Kobiri, Synthetic Dye Application in Textiles: A Review on the Efficacies and Toxicities Involved, Textile & Leather Review. (2022)5:180-198. https://doi.org/10.31881/TLR.2022.22. [2] Y. Liu, C. Li, J. Bao, X. Wang, W. Yu, L. Shao, Degradation of azo dyes with different functional groups in simulated wastewater by electrocoagulation, Water 2022, 14, 123. https//doi.org/10.3390/w14010123. [3] F.R. Abe, A.M. Soares, D.P. de Oliveira, C.A. Gravato, Toxicity of dyes to zebrafish at the biochemical level: Cellular energy allocation and neurotoxicity. Environ. Pollut. 2018, 235, 255–262. https://doi.org/10.1016/j.envpol.2017.12.020. [4] P. Rajaguru, L. J. Fairbairn, J. Ashby, M. A. Willington, S. Turner, L. A. Woolford, N. Chinnasamy, J. A. Rafferty, Genotoxicity studies on the azo dye Direct Red 2 using the in vivo mouse bone marrow micronucleus test, Mutation Research 444(1) (1999) 175-180. https://doi.org/10.1016/S1383- 5718(99)00081-9.

The paper presents preliminary results of corrosion behavior of metal foam with different pore diameters as well as the reference alloy sample EN AC-AlSi9Cu3Fe in 0.5 M NaCl solution. Changes in an open circuit potential with time were monitored, polarization resistance and the potentiodynamic polarization curves were recorded, as well as mass change of samples was determined by the gravimetric method. The surfaces of the samples were recorded after examination with an optical microscope at a magnification of 50 and 100 times. The investigation results showed that higher porosity of the alloy leads to a decrease in the corrosion resistance of the alloy, which is manifested in a reduction of the value of polarization resistance and increasing the values of corrosion current. The gain in the mass of foam samples after gravimetric measurements in a time period of 168 h can be explained by the formation of the corrosion products in the pores of Al-foam samples which the ultrasonic treatment can not effectively remove after immersion in NaCl solution compared to the reference alloy sample.

The electrochemical behavior of CuAlMn alloy in 0.5 mol dm-3 NaCl solution and in the presence of 0.1, 0.3 and 0.5 mol dm-3 Na2SO4 at T = 20 oC and pH = 7 was investigated. Conventional electrochemical techniques were used including open circuit potential, linear and potentiodynamic polarization measurements. The electrochemical measurements showed that the presence of sulfate ions in the chloride solution leads to a decrease in corrosion current density values and to an increase in polarization resistance values for the SO42- ion concentrations of 0.1 and 0.3 mol dm-3. At the highest concentration of sulfate, corrosion current density increases again, and the value of the polarization resistance decreases, probably due to the dissolution of the surface layer of corrosion products. The effect of electrolyte exposure time on 0.5 mol dm-3 NaCl and 0.5 mol dm-3 NaCl + 0.5 mol dm-3 Na2SO4 was examined by measuring with linear polarization method over a period of 24 hours, with the polarization resistance values increasing with time in both NaCl and NaCl + Na2SO4 solution, and these values being significantly higher in the solution with sulphate ions. After electrochemical measurements, the corroded electrode surfaces were examined with an optical and scanning electron microscope.

The objective of this study was to investigate the influence of chloride ion concentration (from 0.1 to 1.5%) and temperature (from 20 to 40 °C) on corrosion behavior of CuAlMnZn alloy in NaCl solution stirred with a magnetic stirrer (150 rpm). Electrochemical techniques such as open circuit potential measurement, linear, potentiodynamic polarization and cyclic voltammetry methods have been applied. The results have been shown that increase in concentration and temperature of NaCl solution leads to a lowering open circuit potential values of alloy, increase in corrosion current density and a decrease in values of the polarization resistance. After polarization measurements, corroded electrode surfaces, were examined with an optical microscope.

CuAlNi alloy has been evaluated for its corrosion behaviour in the 0.5 mol dm-3 H2SO4 stirred solution at the rotation rate of magnetic stirrer of 150 and 450 rpm, at 20 and 40 oC. Investigations were performed using open circuit potential measurements, linear and polarization measurements. After polarization measurements corroded surfaces were evaluated using light microscopy analysis. It was found that increasing in electrolyte temperature leads to higher corrosion damages of alloy while increase in rotation rate of stirrer has smaller impact on corrosion. The presence of intergranular corrosion on the electrode surfaces was clearly seen with optical microscope.

In this paper, the influence of temperature on corrosion behaviour of CuAlMnZn alloy in 0.5 M Na 2 SO 4 solution (pH = 7) was investigated. Investigations have been performed using electrochemical methods, such as open circuit potential, linear and potentiodynamic polarization, cyclic voltammetry and electrochemical impedance spectroscopy. After corrosion measurement, alloy surfaces were examined with a light microscope. The results have shown that investigated alloy has good corrosion resistance towards sulphate anions in neutral solution, which is manifested with relatively low corrosion densities and relatively high values of polarization resistance. By increasing the temperature of the electrolyte, corrosion susceptibility becomes higher. Also, prolonged time of immersion in electrolyte have a negative impact on alloy corrosion stability.

U radu je ispitano korozijsko ponašanje čelika P235 koji se koristi za izradu cijevi u pogonu za mekšanje vode ionskim izmjenjivačima. Ispitivanja su provedena u deioniziranoj vodi bez i uz dodatak komercijalnog biocida i inhibitora korozije, metodom mjerenja gubitka mase te elektrokemijskim metodama (metodom linearne i potenciodinamičke polarizacije). Nakon potenciodinamičkog polarizacijskog ispitivanja površina čelika ispitana je optičkim mikroskopom. Ustanovljeno je da u deioniziranoj vodi dolazi do opće korozije čelika. Dodatak komercijalnog biocida (Chemtec BI01) ne mijenja korozijsko ponašanje čelika, dok primijenjeni komercijalni inhibitor (Chemtec FI30) smanjuje brzinu korozije čelika u deioniziranoj vodi na prihvatljivu vrijednost djelujući kao anodni tip inhibitora. Međutim, anodna polarizacija na uzorku čelika u deoniziranoj vodi izazva pojavu jamičaste korozije, a oštećenja površine su znatno manja u inhibiranim otopinama.

The corrosion behavior of different CuAlMn shape memory alloys (Cu-12%Al-4%Mn, Cu-12.3%Al-5.2%-Mn and Cu-12%Al-6%Mn) in 0.9% NaCl solution at pH = 7.4 and T = 37°C was investigated using open circuit potential measurements, polarization and electrochemical impedance spectroscopy methods. It has been found that the corrosion resistance of the tested samples at open circuit potential increases with increasing Mn content in the alloy, i.e. growing in the order of: Cu-12%Al-4% Mn < Cu- 12.3%Al-5.2%Mn < Cu-12%Al-6% Mn. Namely, the corrosion current decreases in same order, while the polarization resistance and the resistance, thickness and compactness of the surface oxide layer increase. However, at high anodic potentials (E > 0.1 V), the corrosion rate increases with Mn content in the alloy, and light microscopy investigations reveal pits on the surface of Cu- 12.3%Al-5.2%-Mn and Cu-12%Al- 6%Mn alloys, while Cu-12%Al-4%Mn surface is almost clear of any corrosion damage.

This paper presents a review of electrochemical and corrosion investigations on behaviour of CuAlNi and CuAlMn alloys in NaCl solutions, which were carried out within the framework of the project IP-2014-09-3405“ Design of microstructure and functional properties of copper-based shape memory alloys”, supported by the Croatian Science Foundation. The influence of alloys heat treatment on their corrosion behaviour was investigated, as well as the influence of chloride concentration, pH values and electrolyte temperatures. Cu-shape memory alloys were produced by continuous vertical casting and melt spinning method. Investigations were conducted by electrochemical methods such as open circuit current measurement method, electrochemical impedance spectroscopy method, linear and potentiodynamic polarization. Corroded specimens characterization was obtained by optical and scanning electron microscope. Analysis of the corrosion product composition was carried out by EDS method.

Corrosion behavior of CuAlMn and CuAlMnNi alloy ribbons, produced by melt spinning method, were investigated by electrochemical methods such as open circuit potential measurement, linear and potentiodynamic polarization method. Investigations were performed in deaerated 0.9% NaCl solution (T = 37 °C pH = 7.4). Results of electrochemical investigations have shown that CuAlMnNi alloy have higher values of polarization resistance and smaller values of corrosion current density, but in higher anodic potentials region anodic current density for CuAlMn is lower than for CuAlMnNi alloy which indicates higher dissolution of CuAlMnNi alloy. After polarization measurements CuAlMn and CuAlMnNi ribbon surfaces were investigated with light microscope and with SEM/EDS analysis and results have shown that CuAlMnNi alloy is prone to pitting corrosion, while the surface of CuAlMn alloy is partially covered with corrosion product without existence of pits.

The corrosion behavior of the Cu-Al-Ni alloy ribbons obtained by rapid solidification was investigated in 0.9% NaCl solution (pH 7.4) at temperatures of 24, 37 and 50 ºC. Measurements have been performed by electrochemical methods such as monitoring the open circuit potential, linear and potentiodynamic polarization methods. The influence of chloride ions concentration on corrosion of Cu-Al-Ni ribbons has also been investigated in 0.1% and 1.5% NaCl solution. Results of the investigations have shown that an increase in chloride concentration and electrolyte temperature leads to increase the corrosion current density and decrease the polarization resistance values which mean higher corrosion attack on Cu-Al-Ni alloy. Microscopic images have shown significant pitting corrosion damages on the Cu-Al-Ni alloy surface. Increasing the electrolyte temperature increases the surface damages of the electrode due to more intense corrosion. SEM surface images of Cu-Al- Ni electrodes have confirmed that with the elevation of chloride concentration a more intense corrosion attack occurs. EDS surface analysis indicated dominant percentage of copper, chlorine and oxygen on the surface, indicating the formation of copper oxide and chloride as the major corrosion products on the surface. The presence of a small percentage of aluminum indicates its distribution in the form of aluminum oxide and chloride in the surface layer.

The corrosion behavior of the CuAlNiMn alloy in 0.9% NaCl solution at pH 7.4, and temperatures of 25, 37 and 50 oC, was investigated by electrochemical methods such as monitoring the open circuit potential, linear and potentiodynamic polarization methods. Investigations were also performed in 0.9% NaCl solution at 37 oC and different pH of solution (pH = 3.4, 5.4 and 7.4). Results of the investigations have shown that increasing the temperature leads to the shift of the open circuit potential values in the negative direction and also leads to increase of the corrosion current density and decrease of the polarization resistance values. Decreasing the pH of solution leads to the increase of the corrosion current density and decrease the values of polarization resistance. After the polarization measurements, corroded electrode surfaces was examined using an optical microscope and SEM. Microscopic images have shown the significant corrosion damages on the CuAlNiMn alloy surface, which manifests itself in the form of a thin leaf, with a larger part of the surface being covered with sheets of corrosion products loosely bonded to the surface which were elevated from the surface of the electrode. SEM surface analysis revealed the existence of two layers on the surface of the alloy: the exterior is extremely damaged, which represent sheets of loosely bonded surface, and an inner layer that also shows significant corrosion damage. The elemental composition of corrosion products on the surface of the samples was determined by EDS analysis.

The inhibitive action of five different types of honey (oak honey (H1), coniferous honeydew honey (H2), winter savory honey (H3), alder buckthorn honey (H4) and carob tree honey (H5)) were tested as potential corrosion inhibitor of AA 5052 aluminium alloy in 0.5 M NaCl solution. Investigation was performed by electrochemical methods such as linear and potentiodynamic polarization and impedance spectroscopy measurements. The inhibition efficiency was found to increase with increase in honey concentration and inhibition efficiency changes in the following sequence: H3  H5  H4  H2  H1. Results of polarization behaviour have shown that all tested honeys act as mixed type inhibitors with a higher influence on anodic reaction, as expressed in particular for H1 and H2. The adsorption behaviour of investigated inhibitors can be described by the Langmuir adsorption isotherm and the values determined for standard free adsorption energies indicate physical adsorption of organic compounds from honey on the surface of AA 5052 aluminium alloy in NaCl solution.

This paper presents the results of corrosion investigation of cast CuAlNi alloy without and after heat treatment by heating and rapidly cooling in water, in 0.9 % NaCl solution (pH = 7.4 and T = 37 oC). Investigations were performed by open circuit potential measurements, linear and potentiodynamic polarization measurements and electrochemical impedance spectroscopy measurements. After polarization measurements, electrode surfaces were investigated by optical microscope and also with SEM/EDS analysis. The obtained value of corrosion current density is slightly lower (2.35 μA cm-2), and the value of polarization resistance slightly higher (5.359 kΩ cm-2) for the investigation carried out by heat-treated CuAlNi alloy. Optical microscope and SEM images of electrode surfaces have showed that in the 0.9% NaCl solution pitting corrosion evolved on the examined samples of CuAlNi alloy. EDS analysis showed, in both samples, a high amount of chlorine (10.55 – 32.95 wt. %) and oxygen (0.78 – 5.19 wt. %) in corrosion product, and a very high dissolution intensity of alloy main components (Cu, Al and Ni).

The electrochemical behavior in 0.9 % NaCl solution (pH = 7.4) at 37°C of a CuAlNi shape memory alloy (SMA) before and after heat treatment at two different temperatures were studied by means of open circuit potential (EOC) measurements, linear and potentiodynamic polarizations and also OM and SEM-EDX microanalysis. The investigations were performed on samples in as-cast state and two different heat treated states (at temperatures of 850 °C/60’/WQ (K1) and 920 °C/60’/WQ (K2)). Higher polarization resistance and lower corrosion current density of heat treated CuAlNi alloy (K1 and K2) compared to CuAlNi alloy in as-cast state indicate beneficial influence of heat treatment on corrosion resistance of CuAlNi alloy. Scanning electron microscopy investigations revealed deposits of corrosion products on the surface in the form of spikes. The EDS analysis have showed that the surface contains the significant amount of oxygen and chloride compounds. Optical micoscropy shows that after removing the surface layers of corrosion products, damages due to pitting corrosion were clearly visible on electrode surface.

Corrosion behaviour of CuAlNi alloy in 0.9 % NaCl solution (pH = 7.4) were studied at electrolyte temperatures of 25 °C, 37 °C and 50 °C in stagnant solution, by means of open circuit potential measurements (EOC), linear polarization measurements and potentiodynamic polarization measurements. Increasing in electrolyte temperature leads to the stabilization of the open circuit potential of CuAlNi alloy at more negative values and also leads to decrease in values of polarization resistance and increase in values of corrosion current density. Optical microscopy analysis of the CuAlNi surface, after potentiodynamic polarization measurements, indicates the occurrence of pitting corrosion on the alloy surface.

The corrosion behaviour of CuAlNi alloy in 0.9 % NaCl solution at pH = 7.4 and T = 37 °C were studied in still solution and in solution which were stirred with magnetic stirrer. Electrochemical parameters for the CuAlNi alloy were determined using polarization techniques (linear polarization and potentiodynamic polarization) and electrochemical impedance spectroscopy (EIS). The results showed that stirring have negative influence on corrosion stability of CuAlNi alloy and lead to decrease in value of polarization resistance and increase in value of corrosion current density, and also lead to decrease the value of overall impedance of the system. Additionally, the mechanism of corrosion attack developed on the CuAlNi surface was analysed with optical microscopy.

In this work the corrosion properties of Nitinol (NiTi alloy) was studied using different electrochemical techniques such as open circuit potential measurement, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The concentration of dissolved nickel from alloy in 0.9% NaCl solution after EIS measurements was measured with a high- performance atomic absorption spectrometer. Sample made from NiTi alloy with diameter of 4 mm was used. Corrosion properties were tested in 0.9 % NaCl solution at pH=7.4 and temperature 37 °C (simulated body fluid). The NiTi alloy is characterized by a relatively small passive region which indicates the susceptibility for localized corrosion, but the corrosion rate is very low. The oxide film formed on NiTi alloy surface has a double-layer structure consisting of a barrier-type inner layer and a porous outer layer. Also, dissolved nickel ions concentration after 24 hours of the NiTi immersion in 0.9 % NaCl solution is smaller than the daily dietary intake level.

Razvoj ekološki prihvatljivih i učinkovitih tehnologija proizvodnje vodika bitan je za napredak vodikove ekonomije. Jedna od perspektivnih metoda dobivanja vodika temelji se na reakciji aluminija s vodom. Cilj ovog rada je istražiti mogućnost dobivanja vodika kao energenta uporabom ambalažnog otpada, tj. aluminijskih posudica za prehrambene proizvode u vodenoj otopini natrijevog hidroksida. Ispitan je utjecaj omjera broja molova aluminija i natrijevog hidroksida (0, 1, 0, 15 i 0, 2) kao i temperature reakcije u području od 27 do 57 °C na iskorištenje reakcije dobivanja vodika. Eksperimentalno dobiveni podaci su pokazali da povećanjem omjera broja molova reaktanata kao i radne temperature otopine raste volumen oslobođenog vodika, a time i iskorištenje reakcije. Ispitivanja su pokazala da je obnovljivi aluminij zanimljiva alternativa za proizvodnju vodika.

In this work the comparison of corrosion parameters and surface morfology of variuos heat treated states of CuAlNi shape memory alloy before and after potentiodynamic polarization measurement was presented. These measurements were performed on samples in as- casted state (A), after solution annealing at 900 °C for 1 hour (B) and tempering at 300 °C 1 hour (C). After solution annealing and tempering the samples are cooled in water. Corrosion measurement was performed in 0.5 M H2SO4 solution at 25 °C. Surface morphology of samples was investigated by optical microscopy. Martensitic microstructure before corrosion testing was observed. After corrosion tests the intergranular corrosion in all samples was noticed, along with pitting corrosion on tempered sample.

In this work the corrosion behaviour of Ni-Ti (Nitinol) shape memory alloy was studied using different electrochemical techniques including open circuit potential (EOC), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Samples made from nitinol alloy with diameter of 4 mm were used for microstructural and corrosion investigations. Testing solution was 0.9 % NaCl solution at pH=7.4, and temperature 37 °C. Microstructural analysis was performed by the optical and electron scanning microscopy (SEM) equipped with energy dispersive spectrometry (EDS). High values of the oxide film resistance (Rox) and the low value of corrosion current density (icorr) indicated high corrosion resistance of Ni-Ti alloy, but relatively low value of breakdown potential (Eb) indicates the possibility of development localised corrosion attack on the alloy surface. Size of pits was from 10 to 100 m and surface inclusions were initiation sites for the pitting corrosion.

In this work the corrosion behaviour of Ti-Ni (nitinol) shape memory alloy was studied using different electrochemical techniques including open circuit potential (EOC), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Samples made from nitinol alloy with diameter of 4 mm were used for microstructural and corrosion investigations. Testing solution was 0.9 % NaCl solution at pH=7.4, and temperature 37 °C. Microstructural analysis was performed by the optical and electron scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS). High values of the oxide film resistance (Rox) and the low value of corrosion current density (icorr) indicated high corrosion resistance of Ni-Ti alloy, but relatively low value of breakdown potential (Eb) indicates the possibility of development localised corrosion attack on the alloy surface. Size of pits was from 10 to 100 m and surface inclusions were initiation sites for the pitting corrosion.

Shape memory alloys are usable in numerous areas. The effect of the shape memory alloys is basically a recollection on a former deformation of the applied form of the material. In the physical sense, it is a byproduct of the martensite phase transformation in the structure of the homogenous matter. Microstructural analysis of Cu-Al-Ni alloy before corrosion testing was carried out by optical and scanning electron microscopy, respectively. The corrosion behaviour of Cu-Al-Ni shape memory alloy in deaerated 0.5 M NaCl solution at 20 ºC was studied by means of polarization measurements. Surface morphologies of selected specimens after corrosion testing (at -0.2V and 0.4V) were investigated by optical microscope, SEM and EDX microanalysis. The polarization measurements have shown that the corrosion behaviour of Cu-Al-Ni alloy in NaCl solution was dominated by the Cu component. The SEM and EDX microanalysis showed the presence of copper, aluminium and nickel oxides and chlorides on alloy surface.

U radu su provedena ispitivanja korozijskog ponašanja uzoraka nehrđajućeg čelika AISI 316L uzetih s različitih dijelova brodskog cjevovoda. Uzorak 1 predstavljao je uzorak osnovnog materijala nehrđajućeg čelika koji nije bio izložen visokim temperaturama prilikom spajanja cijevi postupkom zavarivanja, dok je uzorak 2 predstavljao uzorak područja zavara (uzorak materijala zavara/zone utjecaja topline). Ispitivanja su provedena pri temperaturama elektrolita od 40 ºC i 60 ºC korištenjem standardne metode ispitivanja nehrđajućeg čelika prema jamičastoj i pukotinskoj koroziji, uporabom otopine željezova(III) klorida (ASTM G48 – 03, metoda A) [1] i metodom cikličke potenciodinamičke polarizacije koja je opisana normom (ASTM G61 – 86) [2]. Ispitivanja korozije nehrđajućeg čelika u otopini FeCl3 u trajanju od 72 h pokazala su da dolazi do gubitka mase uslijed odvijanja korozijskih procesa na površini uzorka, što su potvrdile i snimke površine uzoraka nakon ispitivanja bez i uz uporabu optičkog mikroskopa uz uvećanje 20 i 50 puta. Povećanjem temperature elektrolita raste i gubitak mase ispitivanih uzoraka, što ukazuje na intenzivnije odvijanje korozijskog procesa na povišenim temperaturama. Vidljiva korozijska oštećenja zamijećena su na oba uzorka, s time što je površina osnovnog materijala bila manje oštećena. Ciklička polarizacijska mjerenja u 0.5 mol dm-3 NaCl otopini pokazala su da osnovni materijal (uzorak 1) pokazuje veću otpornost na jamičastu koroziju u odnosu na uzorak područja zavara (uzorak 2). Povećanjem temperature elektrolita dolazi do smanjenja širine pasivnog područja kao i negativiranja pitting potencijala, što ukazuje na manju otpornost materijala prema korozijskom napadu.

U radu je ispitan utjecaj brzine vrtnje rotirajuće disk elektrode i temperature elektrolita na korozijsko ponašanje aluminijeve slitine AA 2017A u aeriranoj 0.5 mol dm-3 NaCl otopini. Ispitivanja su obuhvaćala praćenje potencijala otvorenog strujnog kruga (EOCP) kroz vremenski period od 3 h ; potenciodinamička polarizacijska mjerenja te snimanje elektrodne površine optičkim mikroskopom nakon polarizacijskih ispitivanja. Rezultati ispitivanja su pokazali da povećanjem brzine vrtnje elektrode i porastom temperature elektrolita dolazi do porasta gustoće korozijske struje, što znači i do intenzivnije korozije ispitivane slitine, što je potvrđeno i snimkama površine elektrode optičkim mikroskopom.

U radu je ispitano anodno ponašanje super čistog aluminija (99, 999 %) i aluminija tehničke čistoće (99, 8 %) u 2 M NaCl otopini pri 25, 35 i 45 °C. Uzorci su polarizirani različitim anodnim gustoćama struje (od 100 do 500 mA cm-2) kroz vrijeme od 15 minuta. Tijekom anodne polarizacije snimani su potencijal– vrijeme odgovori, mjeren je volumen vodika koji se izlučivao s površine uzoraka te određen gubitak mase. Po završetku mjerenja, površine uzoraka mikroskopski su analizirane i fotografirane. Ustanovljeno je da kod svih primijenjenih anodnih gustoća struje dolazi do istovremenog otapanja aluminija i izlučivanja vodika. Što je anodna gustoća struje veća, veća je brzina otapanje metala, ali i brzina izlučivanja vodika (pojava negativnog diferencijalnog efekta - NDE). Nadalje, provedena istraživanja pokazuju da prisutne nečistoće ne utječu na anodno ponašanje aluminija u kloridnoj otopini. Za oba ispitivana uzorka dobivene su iste vrijednosti NDE (~ 0, 17) i anodne djelotvornosti (~ 86 %), što ukazuje na činjenicu da se umjesto super čistog aluminija za izradu anoda u Al/zrak kemijskim izvorima struje može koristiti jeftiniji i dostupniji aluminij tehničke čistoće. Temperatura otopine ne utječe na brzinu izlučivanja vodika. Međutim, povećanje temperature negativno utječe na anodnu djelotvornosti oba uzorka aluminija.

The paper presents the results of corrosion properties and microstructure testing of austenitic stainless steel AISI 316L welded sheet. Corrosion testing were carried out in 1M HCl solution using cyclic potentiodynamic polarization at temperatures 20 and 40 ° C. Microstructure analysis were performed before and after corrosion testing on various areas of the welded joint (the base material and at interface weld metal/heat affected zone) using optical and scanning electron microscopy (SEM) equipped with energy dispersion spectrometer (EDS).

U radu su ispitani mehanizam i kinetika rasta oksidnih filmova na Al te na Al-Sn i Al-In slitinama u otopini boratnog pufera (pH 7.8) u uvjetima galvanostatske anodizacije kod različitih gustoća struje 20 – 100 µA cm -2 . Dobiveni potencijal-vrijeme odgovori ukazuju da se rast oksidnih filmova na ispitivanim uzorcima zbiva aktivacijski kontroliranom ionskom vodljivošću pod utjecajem jakog električnog polja kroz oksidni film, prema eksponencijalnom zakonu za ventilne metale. Elektrolitički parametri rasta oksida, konstante A i B, kao i ionska vodljivost kroz oksidni film opadaju redom: Al > Al-Sn > Al-In. Dobiveni iznosi širina energetskih barijera Al i njegovih slitina ukazuju na nesmetan prijenos iona između susjednih mjesta pod djelovanjem visokog električnog polja. Određena je jakost električnog polja kroz okside, a dobivena vrijednost reda veličine MV cm -1 opravdava primjenu mehanizma “aproksimacije visokog polja”.

U radu je ispitano anodno ponašanje Al i Al-In slitine u 2M NaCl otopini. Uzorci su polarizirani anodnim gustoćama struje različitog iznosa (od 20 do 100 mA cm-2) kroz vrijeme od 30 minuta. Tijekom anodne polarizacije snimani su potencijal-vrijeme odgovori, mjeren je volumen izlučenog vodika te određen gubitak mase. Po završetku mjerenja, površine uzoraka mikroskopski su analizirane i fotografirane pri uvećanju od 100 puta. Kod svih primijenjenih anodnih gustoća struje dolazi do istovremenog otapanja uzoraka i izlučivanja vodika. Povećanjem anodne struje linearno se povećava brzina otapanje metala, ali i brzina izlučivanja vodika (pojava negativnog diferencijalnog efekta, NDE). Ustanovljeno je da se legiranjem aluminija malim količinama indija uklanjaju osnovni nedostaci aluminija kao aktivnog anodnog materijala, tj. smanjuje se polarizacija elektrode za čak 0.4 V, smanjuje se NDE te se povećava anodna djelotvornost pri realnim radnim gustoćama struje Al/zrak baterije (i > 80 mA cm-2).