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Zaštita materijala 2. 2018

In Memoriam: Professor NEDELJKO KRSTAJIĆ

Abstract

Nedeljko Krstajić. Professor of Corrosion, Physical Chemistry and Electrochemical Kinetics of The Faculty of Technology and Metallurgy at the University of Belgrade died August 17th. 2017. His working experience which lasted almost 40 years was committed to education and science and by imposing high standards to great achievement of his own, as well as to the surrounding he worked in.

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In Memoriam: Profesor NEDELJKO KRSTAJIĆ

Izvod

Nedeljko Krstajić profesor Korozije, Fizičke Hemije i Elektrohemijske kinetike na Tehnološko-metalurškom fakultetu, Univerziteta u Beogradu, preminuo je 17. avgusta 2017.god. Radni vek, dug gotovo 40, godina profesor Krstajić je posvetio obrazovanju i nauci doprinoseći svojim visokim standardima velikom ugledu kako svom tako i sredine u kojoj je radio i stvarao.

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Mila N. Krstajić Pajić1, Sanja I. Stevanović*2, Vuk V. Radmilović3, Aleksandra Gavrilović-Wohlmuther4, Jelena R. Rogan1, Velimir R. Radmilović1,5, Vladislava M. Jovanović2

1University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia, 2University of Belgrade, Department of Electrochemistry, ICTM, Belgrade, Serbia, 3University of Belgrade, Innovation Center, Faculty of Technology and Metallurgy, Belgrade, Serbia, 4CEST-Centre of Electrochemical Surface Technology GmbH, Wiener Neustadt, Austria, 5Serbian Academy of Sciences and Arts, Belgrade, Serbia

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:66.097.4/.8
doi:10.5937/ZasMat1802159K

Zastita Materijala 59 (2)
159 -166  (2018)

PtAu catalyst with enhanced activity for formic acid oxidation

Abstract

PtAu systems are recognized as good catalysts for the oxidation of formic acid electrooxidation, which is investigated as a possible anodic reaction in low-temperature fuel cells. In this research, bimetallic PtAu nanoparticles, supported on high area carbon Vulcan XC-72R, were synthesized by water in oil microemulsion method. The precursor reduction process took place in a single microemulsion, simultaneously, in the presence of 35% of HCl in the water phase, as a capping agent. Electrochemical behavior of the PtAu/C catalyst was investigated at as prepared electrodes by cyclic voltammetry in 0.5M H2SO4 as a supporting electrolyte, and also in the oxidation of adsorbed CO. The results were compared to the Pt/C catalyst prepared by the same synthesis procedure. PtAu/C catalyst powder was also characterized by X-Ray Diffraction (XRD), High Resolution Transmission Electron Microscopy (HRTEM) and Energy Dispersive X-Ray Spectroscopy (EDS).  Average particle diameter, of 2nm, was calculated from XRD data, which is close to the value of 2.82 nm obtained from TEM images. Compared to identically synthesized Pt nanoparticles, the bimetallic ones are significantly smaller.  EDS maps of PtAu/C sample confirm the presence of both elements, and indicate a very fine distribution of Au in the sample. Elemental composition of about 20% Au and 80% Pt was also determined from these maps.  Prepared catalyst was tested for formic acid electro-oxidation in terms of its activity and stability over the long term cycling. The voltammograms recorded indicate the change of reaction mechanism and better utilization of the catalyst surface in comparison to Pt/C.

Keywords: PtAu nanoparticles, microemulsion method, formic acid electro-oxidation.

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PtAu KATALIZATOR SA POBOLJŠANOM AKTIVNOŠĆU ZA REAKCIJU OKSIDACIJE MRAVLJE KISELINE

Izvod

PtAu sistemi se smatraju veoma dobrim katalizatorima za elektrooksidaciju mravlje kiseline, kao moguće anodne reakcije u niskotemperaturnim gorivnim galvanskim spregovima. U ovom radu bimetalne PtAu nanočestice sintetizovane su mikromulzionim postupkom, i u toku sinteze nanete na ugljenični nosač Vulcan XC-72R. Procesi redukcije prekursora odigravaju se simultano, unutar vodene faze iste mikroemulzije, u prisustvu 35%HCl. Elektrohemijske karakteristike katalizatora ispitivane su cikličnom voltametrijomv na “as prepared” elektrodama u 0.5M H2SO4 kao osnovnom elektrolitu, kao i prilikom oksidacije adsorbovanog CO. Rezultati su upoređeni sa Pt/C katalizatorom sintetizovanim istim postupkom i pod istovetnim uslovima. Pripremljeni PtAu/C prah okarakterisan je takođe difrakcijom X-zraka, transmisionom elektronskom mikroskopijom i energetski disperzionom spektroskoijom. Veličina čestice određena analizom difraktograma X-zraka iznosi 2nm, što je blisko vrednosti dobijenoj analizom TEM snimaka od 2.82 nm. U poređenju sa Pt nanočesticama sintetizovanim na isti način, bimetalne nanočestice su znatno manjeg prečnika. Mape uzorka PtAu/C dobijene energetski disperzionom spektroskopijom potvrđuju prisustvo oba elementa i pokazuju veoma finu distribuciju Au u uzorku. Analizo mapa utvrđeno je i da je katalizator sastava 20% Au i 80% Pt. Konačno, ispitane su aktivnost i stabilnost bimetalnog katalizatora za oksidaciju mravlje kiseline. Snimljeni voltamogrami ukazuju na promenu reakcionog mehanizma i bolje iskorišćenje površine katalizatora u poređenju ra Pt/C katalizatorom sintetizovanim istim postupkom.

Ključne reči: PtAu nanočestice, mikroemulziona metoda, oksidacija mravlje kiseline.

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Mihailo Mrdak1*, Časlav Lačnjevac2, Marko Rakin3

1Research and Development Center, IMTEL komunikacije a.d., Belgrade, Serbia, 2University of Belgrade, Faculty of Agriculture, Belgrade, Serbia, 3University of Belgrade, Faculty of Technology and Metallurgy, Belgrade,Serbia

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:620.186.197.6
doi:10.5937/ZasMat1802167M

Zastita Materijala 59 (2)
167 – 172  (2018)

Mechanical and structural features of Nb coating layers deposited on steel substrates in a vacuum chamber

Abstract

In this paper analyzed was the influence of implementation of inert Ar gas and a mixture of inert plasma Ar / He gases in a vacuum chamber on the deposition of reactive niobium (Nb) powder. The aim of this paper was to deposit coating layers of high density, without oxide content, that will find application in the field of biomedicine. Detailed examination was performed of mechanical properties of microhardness using the HV0.3 method, of tensile bond strength by tensile testing and of the microstructure of the coating layers in the deposited state and after etching. For etching a solution of nitric acid HNO3 and hydrofluoric acid HF in a ratio of 1:1was used. It was found that inert gases, at low pressure prevent the reaction of gases with the metal droplets of molten Nb powder particles during the plasma spray deposition process. The density of the deposited coating in vacuum chamber is higher than that of coatings which are deposited at atmospheric pressure with reactive plasma gases N2 and H2. This is attributed to the elimination of thin oxide and nitride films at the interlamellar Nb contact, substantially increasing the ductility of the coating, eliminating the micro cracks through the deposited layers, which was confirmed by metallographic examination of samples. Tests have shown that VPS – Nb coating layers have mechanical properties and microstructure which completely enable the use of the coating on implants.

Keywords: niobium, coatings, mechanical properties, vacuum, microhardness, bond strength

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MEHANIČKE I STRUKTURNE KARAKTERISTIKE SLOJEVA PREVLAKE Nb DEPONOVANE U VAKUUMU

Izvod

U ovom radu ispitan je uticaj primene inertnog gasa Ar i mešavine inertnih plazma gasova Ar / He u vakuum komori na depoziciju reaktivnog praha niobijuma (Nb). Cilj rada je bio da se deponuju slojevi prevlake visoke gustine bez sadržaja oksida koji će naći primenu u oblasti biomedicine. Izvršena su detaljna ispitavanja mehaničkih karakteristika mikrotvrdoće metodom HV0.3 i zatezne čvrstoće spoja ispitivanjem na zatezanje i mikrostrukture slojeva prevlake u deponovanom stanju i posle nagrizanja. Za nagrizanje se koristio rastvor azotne kiseline HNO3 i fluorovodoniče kiseline HF u odnosu 1 : 1. Utvrđeno je da inertni gasovi na niskom pritisku sprečavaju reakciju gasova sa metalnim kapima istopljenih čestica praha Nb tokom plazma sprej depozicije. Gustina deponovane prevlake u vakuumu je veća u odnosu na prevlake koje se deponuju na atmosferskom pritisku sa reaktivnim plazma gasovima N2 i H2. Ovo se pripisuje eliminisanju tankih filmova oksida i nitrida na međulamelarnim kontaktnim Nb, što značajno povećava duktilnost prevlake, eliminišući mikro pukotine kroz deponovane slojeve, što su potvrdila metalografska ispitivanja uzoraka. Ispitivanja su pokazala da slojevi VPS – Nb prevlake imaju mehaničke karakteristike i mikrostrukturu, koje u potpunosti omogućavaju primenu prevlake na implantima.

Ključne reči: niobijum, prevlaka, mehanička svojstva, vakuum, mikrotvrdoća, čvrstoća spoja.

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Mihael Bučko1*, Sanja I. Stevanović2, Jelena B. Bajat3

1University of Defense, Military Academy, Belgrade, Serbia, 2University of Belgrade, I CTM – IEC, Belgrade, Serbia, 3University of Belgrade,Faculty of Technology and Metallurgy, Belgrade, Serbia

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:620.195.197.5
doi:10.5937/ZasMat1802173B

Zastita Materijala 59 (2)
173 – 181  (2018)

Tailoring the corrosion resistance of Zn-Mn coating by electrodeposition from deep eutectic solvents

Abstract

Well adhered, homogenous coatings were obtained from deep eutectic solvents (DES) based on choline chloride and urea, at current densities up to 20 mA cm-2. The coatings’ morphology was analyzed by atomic force microscopy, determining the agglomerates size and distribution. The corrosion stability of these deposits was analyzed in 3 wt. % NaCl solution by electrochemical impedance spectroscopy and polarization measurements, and compared with coatings deposited from a conventional water-based electrolyte. The influence of deposition current density and surface morphology, as well as of DES type, on the corrosion resistance was analyzed. It was shown that electrodeposition from DES enables incorporation of greater Mn amounts, that induced a pseudo-passivation effect, which, in turn, resulted in superior corrosion resistance.

Keywords: electrochemical deposition, Zn-Mn alloy, coatings, deep eutectic solvent, corrosion stability.

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POBOLJŠANJE KOROZIONE POSTOJANOSTI Zn-Mn PREVLAKE, ELEKTROHEMIJSKIM TALOŽENJEM IZ DUBOKIH EUTEKTIČKIH SMEŠA

Elektrohemijskim taloženjem iz eutektičke smeše na bazi holin hlorida i uree, gustinama struje taloženja do 20 mA cm-2 dobijene su homogene prevlake Zn-Mn legure, dobre adhezije na čeliku. Morfologija dobijenih prevlaka je ispitivana mikroskopijom međuatomskih sila. Određene su veličine aglomerata kristalnih zrna i njihova raspodela po površini u zavisnosti od vrste rastvora za taloženje i gustine struje taloženja. Koroziona stabilnost prevlaka legura je ispitivana spektroskopijom elektrohemijske impedancije i polarizacionim merenjima u rastvoru 3 % NaCl i upoređena je sa svojstvima prevlaka dobijenih elektrohemijskim taloženjem iz vodenih rastvora. Pokazan je uticaj gustine struje taloženja, morfologije prevlaka, kao i vrste eutektičke smeše, na otpornost elektrohemijski taloženih prevlaka legura prema koroziji. Elektrohemijskim taloženjem iz eutektičkih smeša je moguće dobiti prevlake Zn-Mn legure sa većim sadržajem Mn, koje dovode do pojave pseudo-pasivnog sloja na površini, povećavajući njihovu korozionu stabilnost.

Ključne reči: elektrohemijsko taloženje, Zn-Mn legure, eutektičke smeše, koroziona stabilnost

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Vincent Agnes Brigitta 1, Chinnaiyan ThangaveluSusai Rajendran3*, Abdulhameed Al-Hashem4

1SBM college of Engineering and Technology, Department of Chemistry, Thamaraipadi, Dindigul , Tamil Nadu, India,2 EVR Govt Arts College, Trichy, India, 3St. Antony’s College of Arts and Science For Women, Research Center, Department of Chemistry, Thamaraipadi, Dindigul,Tamil Nadu, India, 4Kuwait Institute for Scientific Research (KISR), Petroleum Research Center,Kuwait

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:620.197.2
doi:10.5937/ZasMat1802182V

Zastita Materijala 59 (2)
182 – 188  (2018)

Corrosion resistance of SS18/8 alloy, SS316L alloy, Gold18carat and Gold 22 carat in artificial saliva in the absence and presence of erythromycin tablet 500mg

Abstract

Corrosion resistance of SS18/8 alloy, SS316L alloy, Gold18carat and Gold 22 carat in artificial saliva in the absence and presence of Erythromycin tablet 500mg has been evaluated by electrochemical study such as polarization study. For SS316L alloy, Gold 18 carat and Gold 22 carat, Polarization study leads to the conclusion that corrosion resistance of SS316L alloy, Gold 18 carat and Gold 22 carat decreases in the order : AS + Erythromycin > AS. Hence, people clipped with an orthodontic wire made of SS316 alloy, Gold 18 carat and Gold 22 carat can take Erythromycin tablet orally without any hesitation. For SS18/8 alloy, polarization study leads to the conclusion that corrosion resistance of SS18/8 alloy decreases in the order: AS > AS + Erythromycin. So, people clipped with an orthodontic wire made of SS18/8, should avoid taking Erythromycin tablet orally.

Keyword: corrosion resistance, polarization study, orthodontic wire, SS18/8 alloy, SS316L alloy, Gold 18carat and Gold 22 carat, Erythromycin.

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KOROZIJSKA OTPORNOST LEGURE SS 18/8, LEGURE SS316L, ZLATA 18 KARATA I ZLATA 22 KARATA U VEŠTAČKOJ PLJUVAČKI U ODSUSTVU I PRISUSTVU TABLETA ERITROMICINA 500mg

Otpornost na koroziju legure SS 18/8, legure SS316L, zlata 18 karata i zlata 22 karata u veštačkoj pljuvački u odsustvu i prisustvu tablete Erithromicin 500 mg je procenjena elektrohemijskim ispitivanjem, kao što je ispitivanje polarizacije. Za leguru SS316L, zlato 18 karata i zlato 22 karata, studija polarizacije dovodi do zaključka da se otpornost na koroziju legure SS316L, Gold 18 karata i Gold 22 karata smanjuje u redosledu: AS + Erithromicin> AS. Stoga, ljudi koji u sebi imaju ortodontsku žicu izrađenu od legure SS316, zlato 18 karata i zlato 22 karata, mogu uzimati Eritromicin tablete oralno bez ikakvih oklevanja. Za leguru SS 18/8, studija polarizacije dovodi do zaključka da se otpornost na koroziju legure SS 18/8 smanjuje u redosledu: AS> AS + Erithromicin. Dakle, ljudi koji u imaju u sebi ortodontsku žicu izrađeniu od legure SS 18/8, treba izbegavati uzimanje Eritromicin tablete oralno.

Ključne reči: otpornost na koroziju, ispitivanje polarizacije, ortodontska žica, legure SS18/8, legure SS316L, zlato 18 karata, zlato 22 karata, eritromicin.

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Mukesh Kumar Sinha*, Biswa Ranjan Das, Namburi Eswara Prasad, Brij Kishore, Kamal Kumar

Defence Materials & Stores Research & Development Establishment, Defence Research & Development Organization (DRDO), Kanpur, Uttar Pradesh, India

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:620.197.6(n)
doi:10.5937/ZasMat1802189K

Zastita Materijala 59 (2)
189 – 198  (2018)

Exploration of nanofibrous coated webs for chemical and biological protection

Abstract

Worldwide used Nuclear, Biological and Chemical (NBC) protective clothing has very limited protection against bacteria. Apart from this, NBC clothing has ample scope of improvements of some important features like comfort, better protection against CWA and weight reduction. The purpose of this research work is to establish process of integrating nanofibrous coated web with adsorbent layer of NBC clothing to achieve required biological protection and better chemical protection with reducing its weight. In this study, the developed activated carbon sphere (ACS) laminated structures are integrated with nanofibrous webs of Polyvinyl Alcohol (PVA). Design of the PVA integration process with adsorbent layer is strategically decided. PVA nanowebs of different morphological structures and coating densities (0.03-0.61 g/m2) by latest nozzle-less nanospider technology are coated on polypropylene (PP) spun bonded nonwoven fabric. Then coated PP fabric is stitched at the boarder-line with adsorbent layer for formulating the composite layer. The various attributes and functional properties of PVA nanofibrous integrated absorbent layer is characterized by using FESEM, 1,3-Dichloropropane test (stimulant for mustard gas), durability test, pore size, air permeability and water vapour transmission rate. The reported research work showed that by integrating nanofibrous coated web layers into ACS laminated adsorbent layer of NBC clothing, it’s now offering various functional properties like additional bacterial filtration and chemical protection at a lighter weight.

Keywords: adsorbent layer, biological, chemical, nanofibre, nanowebs, protection.

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ISTRAŽIVANJE NANOFIBRIRANIH OBLOŽENIH TRAKA  ZA HEMIJSKU I BIOLOŠKU ZAŠTITU

Izvod

Zaštitna odeća od nuklearne, biološke i hemijske (NBH) zaštite širom sveta ima veoma ograničenu zaštitu od bakterija. Osim toga, odeća NBH ima dosta poboljšanja u nekim važnim osobinama kao što su udobnost, bolja zaštita od CVA i smanjenje težine. Svrha ovog istraživačkog rada je uspostavljanje procesa integrisanja nanofibrirane obložene mreže sa adsorbentnim slojem NBH odeće radi postizanja potrebne biološke i hemijske zaštite i smanjivanje njegove težine.

U ovom istraživanju razvijena je laminirana struktura aktivne ugljenične sfere (ACS) integrisana sa nanofibriranim mrežama od polivinil alkohola (PVA). Dizajn procesa integracije PVA sa adsorbentnim slojem strateški je rešen.

PVA različitih morfoloških struktura i gustina premaza (0,03-0,61 g/m2) najnovijom tehnologijom ”pauka” bez nanosa, su naneti na polipropilen (PP) vezane netkane tkanine. Tako obložena PP tkanina je spojena na graničnoj liniji sa slojem adsorbenta na kompozitnom sloju. Različiti atributi i funkcionalne osobine PVA nanofibroznog integrisanog upijajućeg sloja karakterišu upotrebom FESEM-a, testa 1,3-Dihloropropana (stimulans za iperit), testa izdržljivosti, veličine pora, prozračnosti vazduha i brzine prenosa vodene pare. Navedena istraživanja su pokazala da su integracijom nanofibriranih slojeva u sloj adsorbentnih slojeva NBH odeće, povećane razne funkcionalne osobine kao što su dodatna bakterijska i hemijska zaštita i smanjenje težini odela.

Ključne reči:  sloj adsorbenta, biološka i hemijska zaštita, nanofiber.

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Masataka Sakai1, Shota Noda1, Yoshio Kobayashi1*, Ken-ichi Watanabe2, Hidekazu Koda2, Hiroshi Kunigami2, Hideki Kunigami2

1Ibaraki University, Department of Biomolecular Functional Engineering, College of Engineering, Hitachi, Japan,
2K. K. Shinko Kagaku Kogyosho, Koshigaya, Saitama, Japan

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:620.195
doi: 10.5937/ZasMat1802199S

Zastita Materijala 59 (2)
199 – 205  (2018)

Fabrication of palladium/platinum core-shell nanoparticles by electroless metal plating

Abstract

An electroless metal plating method was used to form metallic platinum (Pt) shells on metallic palladium (Pd) nanoparticles. The electroless metal plating method comprised two steps: (1) reduction of Pd ions to fabricate Pd nanoparticles and (2) deposition of Pt nuclei and the following formation of Pt shells by immersing the Pd nanoparticles in a Pt-plating solution. TEM observation revealed that the nanoparticles had a size of 5.7±1.9 nm, were composed of Pd nanoparticles as core and Pt shells. The Pd/Pt core-shell nanoparticles were immobilized electrostatically on carbon support surface-modified with poly(diallyldimethylammonium chloride) (Pd/Pt/C). Cyclic voltammetry revealed that the Pd/Pt/C exerted hydrogen adsorption/desorption, expecting the Pd/Pt/C to function as catalyst for fuel cell.

Keywords: palladium, platinum, core-shell, particles, electroless metal plating, catalyst.

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IZRADA PALADIJUM/PLATINSKOG JEZGRA NANOČESTICA  ELEKTROSTATSKIM METALNIM PREMAZOM

Izvod

Metoda pločica bez elektrolita je korišćena da se formiraju metalne čestice školjke platine (Pt) na nanočesticama metalnog paladijuma (Pd). Metoda neplastičnog metala je obuhvatila dva koraka: (1) smanjenje jona Pd za proizvodnju Pd nanočestica i (2) deponovanje jezgra Pt i sledeće formiranje Pt školjki potapanjem Pd nanočestica u Pt- rastvor. TEM posmatranje je otkrilo da nanočestice imaju veličinu od 5,7 ± 1,9 nm, sastoje se od nanočestica Pd kao jezgra i Pt školjki. Nanočestice Pd / Pt jezgra su bili elektrostatički imobilizovani na površini ugljenika, modifikovanim sa poli (diallildimethilammonium chloride) (Pd / Pt / C). Ciklična voltametrija pokazala je da je Pd / Pt / C imala adsorpciju vodonika / desorpciju, očekujući da Pd / Pt / C funkcioniše kao katalizator za gorivne ćelije.

Ključne reči: paladijum, platina, jezgro -čestice, elektrostatska metalna galvanizacija, katalizator.

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Žaklina Tasić, Marija Petrović Mihajlović, Milan Radovanović, Milan Antonijević*

University of Belgrade, Technical Faculty in Bor, Bor, Serbia

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:620.197.3
doi: 10.5937/ZasMat1802206T

Zastita Materijala 59 (2)
206 – 215  (2018)

5-chloro-1H-benzotriazole and potassium sorbate as binary corrosion inhibitor of copper in acidic solution

Abstract

The effect of potassium sorbate as well as 5-chloro-1H-benzotriazole – potassium sorbate on the corrosion behavior of copper in acidic sulfate media containing Cl ions was examined. For this purpose, the electrochemical methods and quantum chemical calculations were used. The inhibition efficiency in the presence of 5-chloro-1H-benzotriazole – potassium sorbate was higher than in the presence of potassium sorbate. Also, the inhibition efficiency of binary inhibitor depends on the concentration of Cl ions added in sulfate solution. According to the results obtained by potentiodynamic polarization measurements, both potassium sorbate and 5-chloro-1H-benzotriazole – potassium sorbate behave as mixed type inhibitors. Quantum chemical parameters are in good agreement with results obtained by electrochemical measurements.

Keywords: inhibition efficiency, 5-chloro-1H-benzotriazole, potassium sorbate, quantum chemical calculations, electrochemical measurements.

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5-HLOR1H-BENZOTRIAZOL I KALIJUM-SORBAT KAO DVOKOMPONENTNI INHIBITOR KOROZIJE BAKRA U KISELOJ SREDINI 

Izvod

Ispitivan je uticaj kalijum-sorbata i dvokomponentnog inhibitora, 5-hlor-1H-benzotriazol – kalijum-sorbat, na koroziono ponašanje bakra u kiselom rastvoru sulfata u prisustvu Cl jona. Za navedeno istraživanje korišćene su elektrohemijske metode i kvantno-hemijski proračuni. Postignuta je veća vrednost efikasnosti inhibicije u prisustvu 5-hlor-1H-benzotriazol – kalijum-sorbat u odnosu na prisustvo samog kalijum-sorbata. Isto tako, efikasnost inhibicije dvokomponentnog inhibitora zavisi od koncentracije dodatih Cl jona kiselom rastvoru sulfata. U skladu sa postignutim rezultatima na osnovu potenciodinamičkih polarizacionih merenja, kalijum-sorbat i 5-hlor-1H-benzotriazol – kalijum-sorbat se ponašaju kao mešoviti tip inhibitora. Parametri dobijeni na osnovu kvantno-hemijskih proračuna su u saglasnosti sa rezultatima koji su postignuti elektrohemijskim merenjima.

Ključne reči: efikasnost inhibicije, 5-hlor-1H-benzotriazol, kalijum-sorbat, kvantno-hemijski proračuni, elektrohemijska merenja

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Tamara Apostolović1, Jelena Tričković1*, Aleksandra Šućurović2, Marijana Kragulj Isakovski1, Snežana Maletić1, Srđan Rončević1, Božo Dalmacija1

1University of Novi Sad, Faculty of Sciences, Department for Chemistry, Biochemistry and Environmental Protection, Novi Sad, Serbia, 2Technical College of Applied Sciences in Zrenjanin, Zrenjanin, Serbia

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:620.198.7(n)
doi: 10.5937/ZasMat1802216A

Zastita Materijala 59 (2)
216 – 225  (2018)

Adsorption kinetics of divalent metals on amino-functionalized carbon nanomaterial

Abstract

The subject of this study was to investigate the adsorption behavior of selected divalent metals (Cu (II), Cd (II), Pb (II)) on amino-functionalized multiwalled carbon nanotubes, MWCNT-NH2, at four selected pH values (3; 4.5, 6, 11), in order to estimate the possibility of using MWCNT-NH2 to remove ion metal from aqueous solutions at relatively low concentrations (0.01-0.1 mg L-1). The focus of the study was to determine the adsorption mechanism at the experimental conditions. The adsorption of divalent metal ions on MWCNT-NH2 was best described by the pseudo-second order kinetics model, which indicates that adsorption can be attributed to the chemical interactions between the adsorbates and the binding groups on the surface of the adsorbent. Modeling the adsorption rate by the Weber-Morris diffusion model indicated that intra-particle diffusion, although a slower step than external diffusion, is not the only limiting step in the adsorption process, and that the interaction of the investigated ions with the binding sites on the adsorbent surface also control the adsorption rate. Assessment of the impact of pH on the adsorption rate has shown that the pH value, in the investigated range, has the highest effect on the adsorption efficiency of Cu (II) and the lowest for the removal of Cd (II).

Key words: nanomaterials, divalent metals, adsorption, kinetics.

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KINETIKA ADSORPCIJE DVOVALENTNIH METALA NA AMINOFUNKCIONALIZOVANOM UGLJENIČNOM NANOMATERIJALU

Izvod

Predmet istraživanja ovog rada bio je ispitivanje adsorpcionog ponašanja odabranih dvovalentnih metala (Cu(II), Cd(II), Pb(II)) na amino-funkcionalizovanim višeslojnim ugljeničnim nanocevima, MWCNT-NH2, na četiri odabrane pH vrednosti (3; 4,5; 6 i 11), a u cilju ispitivanja mogućnosti primene MWCNT-NH2 za uklanjanje jona metala iz vodenih rastvora u oblasti relativno niskih koncentracija (0,01-0,1 mg L-1). Fokus rada je bio na utvrđivanju mehanizma procesa adsorpcije u ispitivanim uslovima. Adsorpciju jona dvovalentnih metala na MWCNT-NH2 najbolje je opisao reakcioni model pseudo-drugog reda što znači da adsorpcija može biti pripisana uspostavljanju hemijskih interakcija između adsorbata i vezivnih grupa na površini adsorbenta. Modelovanje brzine Weber Morris-ovim difuzionim modelom ukazalo je na to da unutarčestična difuzija, iako sporiji korak od eksterne difuzije, nije jedini ograničavajući korak u procesu adsorpcije, već su za to odgovorne i interakcije ispitivanih jona sa vezivnim mestima na površini adsorbenta. Procena uticaja pH vrednosti na brzinu procesa pokazala je da pH vrednost, u ispitivanom opsegu, ima najveći uticaj na efikasnost adsorpcije Cu(II), a najmanji na uklanjanje Cd(II).

Ključne reči: nanomaterijali, dvovalentni metali, adsorpcija, kinetika.

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Abd El-Aziz S. Fouda1, Ali M. El-Azaly2

1El-Mansoura University, Department of Chemistry, Faculty of Science, El-Mansoura, Egypt,  2Nile higher Institute for Engineering and Technology, El-Mansoura, Egypt

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:620.197.3
doi: 10.5937/ZasMat1802226E

Zastita Materijala 59 (2)
226 – 236  (2018)

Expired concor drug as potential nontoxic corrosion inhibitor for 304 stainless steel in hydrochloric acid solution

Abstract

The effect of the expired concor drug as the corrosion inhibitor for stainless steel type 304 (304SS) in 2M HCl solution has been investigated using electrochemical and non-electrochemical techniques. Some kinetic corrosion parameters were calculated. The inhibition efficiency (% I) increases with rising concentration of the drug and maximum efficiency (85.8 %) reached 300 ppm. The polarization measurements indicated that the expired concor drug was of the mixed type and inhibits corrosion by adsorption on the surface of 304SS due to the presence of more than one active center in its molecule. The adsorption was obeyed Langmuir adsorption isotherm. The activation energy and thermodynamic parameters were also calculated and discussed.

Keywords: 304 SS; expired concor drug, HCl, Langmuir isotherm, corrosion inhibition.

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VREMENSKI ISTEKAO LEK KAO POTENCIJALNI  NETOKSIČNI INHIBITOR KOROZIJE ZA 304 NERĐAJUĆI ČELIK U RASTVORU HLOROVODONIČNE KISELINE 

Izvod

Efekat vremenski isteklog leka kao inhibitora korozije za nerđajući čelik tipa 304 (304SS) u 2M HCl rastvoru je ispitan korišćenjem elektrohemijskih i ne-elektrohemijskih tehnika. Izračunati su neki parametri kinetičke korozije. Efikasnost inhibicije (% I) povećava se sa rastućom koncentracijom leka i maksimalna efikasnost (85,8%) je dostigla 300 ppm. Polarizacijska merenja pokazala su da je vremenski istekli lek bio inhibitor mešovitog tipa i inhibirao je koroziju adsorpcijom na površini 304SS zbog prisustva više od jednog aktivnog centra u njegovom molekulu. Adsorpcija se ponašala po izotermi adsorpcije Langmira. Takođe, proračunati su i razmatrani energija aktivacije i termodinamički parametri.

Ključne reči: 304 SS, vremenski istrošeni lek, HCl, Langmirova izoterma, inhibicija korozije.

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Tsvetina Dobrovolska1, Uroš Lačnjevac2, Nikola Tasić2, Borka Jović2, Vladimir Jović2, Nevenka Elezović2*

1Bulgarian Academy of Sciences, Institute of Physical Chemistry, Sofia, Bulgaria, 2University of Belgrade, Institute for Multidisciplinary Research, Belgrade, Serbia

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:620.193.91
doi: 10.5937/ZasMat1802237D


Zastita Materijala 59 (2)
237 – 242  (2018)

Spatio-temporal structures of electrodeposited indium based alloys

Abstract

Ag-In, Pd-In and Co-In alloy coatings were electrodeposited under galvanostatic conditions from different solutions. The appearance and the composition of coatings were investigated by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS).

The appearance of spatio-temporal structures on the surface od electrodeposited alloy layers is characteristic for all three indium containing alloys. Well-distinguished spirals were detected only at the surfaces of Ag-In and Co-In alloys, while for Pd-In alloy spatiotemporal structures are characterized with the valleys of different shapes surrounded by hills.

In the case of Ag-In and Pd-In alloy coatings the cross-section does not show the presence of alloy layers with different composition, due to the fact that spatiotemporal structures are of large dimensions and cannot be seen on the high magnification images of the cross-sections.

EDS line scan of the cross-section of Co-In alloy layers indicates the presence of layers with different compositions at high magnification, confirming that spatiotemporal structures are placed not only on the surface, but also in the bulk of the alloy coating.

Keywords: spatio-temporal structures, spirals, electrodeposited In alloys, cross-section.

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Prostorno-vremenske strukture kod elektrohemijski istaloženih legura na bazi Indijuma

Izvod

Prevlake legura Ag-In, Pd-In i Co-In dobijene su elektrohemijskim taloženjem pri konstantnoj gustini struje iz različitih rastvora. Površinski izgled i sastav prevlaka su ispitivani skenirajućom elektronskom mikroskopijom (SEM) i energetski disperzivnom rentgenskom spektroskopijom (EDS).

Pojava prostorno-vremenskih struktura na površini elektrohemijski istaloženih prevlaka legura je karakteristična za sve ispitivane legure indijuma. Jasno definisane spiralne strukture su detektovane na površinama Ag-In i Co-In legura,dok su prostorno-vremenske strukture kod Pd-In legura okarakterisane pojavom udolina različitog oblika koje su okružene uzvišenjima.

Na poprečnom preseku legura Ag-In i Pd-In nije moguće detektovati slojeve sa različitim sastavom, jer su prostorno-vremenske strukture velikih dimenzija koje se ne mogu videti na slikama velike rezolucije (poprečni preseci). Linijska EDS analiza poprečnog preseka prevlake Co-In legure ukazuje na prisustvo slojeva različitih sastava (različite faze) i time potvrđuje prisustvo spirala ne samo na površini, već i po dubini taloga.

Ključne reči: prostorno-vremenske strukture, spirale, elektrohemijsko taloženje In legura, poprečni presek taloga.

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Branimir N. Grgur*, Lazar Marunkić

University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:620.193.4
doi: 10.5937/ZasMat1802243G

Zastita Materijala 59 (2)
243 – 248 (2018)

The influence of chloride anions on the pitting corrosion of aluminum alloy EN 46000

Abstract

The corrosion behavior of AlSi9Cu3 aluminum alloy, which is commonly used for manufacturing radiators of remote central heating systems, is investigated. The tendency for pitting corrosion is investigated in the phosphate buffer solution at pH = 7, in the sodium chloride anion concentration range 10-300 mg dm-3. The critical pitting potentials are estimated. The behavior of aluminum alloy and copper corrosion couple is also investigated.

Keywords: Corrosion, Central heating systems, Radiators, Critical potential

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UTICAJ HLORIDNIH ANJONA NA TAČKASTU KOROZIJU LEGURE ALUMINIJUMA EN 46000

Ispitano je korozivno ponašanje aluminijumske legure AlSi9Cu3, koje se obično koristi za proizvodnju radijatora u sistema daljinskog centralnog grejanja. U fosfatnom puferskom rastvoru pri pH = 7, u opsegu koncentracije natrijum hlorida 10-300 mg dm-3 ispitivana je tendencija ka tačkastoj korozije. Procenjeni su kritični potencijali pri kojima može doći do tačkaste korozije. Ispitano je i ponašanje aluminijumske legure i bakarnog korozionog sprega.

Ključne reči: korozija, sistemi centralnog grejanja, radijatori, kritični potencijal.

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Svetomir Hadži Jordanov*

University UKIM, Faculty of Technology and Metallurgy, Skopje, Macedonia

Review paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:620.21
doi: 10.5937/ZasMat1802249H

Zastita Materijala 59 (2)
249 – 255 (2018)

Raw materials in future: some novel sources?

Abstract

A survey is given on the present status of raw materials reserves, trends in consumption rate, etc. The raw materials are further depleting and crisis in supply is possible in future. The components of the supply/consumption complex are identified and analyzed in an attempt to get closer in balancing them.

Approach was accepted not to limit the possible sources of raw materials. Some extraordinary sources were considered, as e.g., exploitation of metals from the Earths deep interior and of planet Mars.  No matter that the feasibility of such processes in near future is with low chances, one should keep them in mind as one of the promises of new technologies.

Another, quite futuristic chance was selected and analyzed. Space mining, the subject of past dreams, seems to get closer to its birth. The asteroid 16 Psyche, is declared to provide iron supply for ‘several million of years’ (!?), and activities are in course to get prepared for accepting such a gift from the sky. Varieties of exploitation possibilities, parameters of space mining, costs, property and other economy related aspects are already considered. The most distinctive characteristic of this asteroid is that it is free of crust, i.e. only metallic core does exists, so that there is no non-metallic layer of burden to be removed when exploiting it.

Keywords: raw materials, sources, traditional vs. new (revolutionary new), space mining (?)

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SIROVINE ZA BUDUĆNOST: IMA LI NOVIH IZVORA? 

Izvod

Dat je pregled sadašnjeg stanja rezervi sirovina, trendova njihove potrošnje i slično. Potvrđen je fakt da se sirovine i dalje iscrpljuju i da je moguća kriza u snabdevanju sirovinama u budućnosti. Identifikovane su komponente kompleksa zalihe/potrošnja i dalje analizirane u pokušaju da se približimo njihovom balansiranju.

Prihvaćen je pristup da se ne ograničava izbor mogućih izvora sirovina, tako da su razmatrani i neki neuobičajeni izvori. Na primer, analizirane su mogućnosti eksploatacije metala iz velikih dubina unutrašnjosti Zemlje, kao i sa drugih planeta (Mars). Bez obzira na to što je izvodljivost ovih postupaka u bližoj budućnosti malo verovatna, treba ih ipak imati na umu kao mogućnosti koje mogu da ponude nove tehnologije.

Odabrana je i analizirana i jedna druga, potpuno futuristička mogućnost. Snabdevanje rudama iz svemira, predmet snova iz nekadašnjih vremena, izgleda da se bliži svom ostvarenju. Pažnju nam privlači asteroid sa izuzetno visokim sadržajem gvožđa. Nazvan 16 Psyche, metalni asteroid sa najvećom masom, najavljen je da može omogućiti snabdevanje gvožđem za “nakoliko miliona godina” (!?). Bez obzira na njegovu veliku udaljenost od Zemlje (predviđa se da će ekspediciji do njega trebati čitavih 5 godina svemirskog putovanja), u toku su analize i druge konkretnije aktivnosti koje treba da nas pripreme za prihvatanje ovako izvanrednog ‘poklona sa neba’. Već se uveliko razmatraju načini moguće eksploatacije, parametri rudarenja u vasioni, troškovi, pravo sopstvenosti i drugi ekonomski aspekti. Najizraženija (i najcenjenija) osobina ovog asteroida je što on nema koru, odnosno ima samo metalno jezgro, tako da ne postoji sloj nemetalne raskrivke koji se mora ukloniti da bi se došlo do metala.

Ključne reči: sirovine, izvori, tradicionalni i novi (revolucionarno novi), snabdevanje rudama iz svemira.

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Nebojša D. Nikolić1*, Vesna M. Maksimović2, Goran Branković3, Predrag M. Živković4, Miomir G. Pavlović1

1University of Belgrade, ICTM-Department of Electrochemistry, Belgrade, Serbia, 2University of Belgrade, Vinča Institute of Nuclear Sciences, Belgrade, Serbia, 3University of Belgrade, Institute for Multidisciplinary Research, Belgrade, Serbia, 4University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:620.186/187
doi: 10.5937/ZasMat1802256N

Zastita Materijala 59 (2)
256 – 264  (2018)

Correlation between crystal orientation and morphology of electrolytically produced powder particles: analysis of the limiting cases

Abstract

Lead and nickel powder particles were produced by the processes of electrolysis and characterized by scanning electron microscope (SEM). The X-ray diffraction (XRD) analysis of the produced particles was done. Morphologies of Pb and Ni particles were correlated with their crystal structure at the semi quantitative level by determination of “Texture Coefficients” (TC) and “Relative Texture Coefficient” (RTC). The two dimensional (2D) dendritic particles of lead of different degree of ramification were obtained by the potentiostatic regime of electrolysis from the nitrate, acetate and hydroxide electrolyte. The spongy-like particles of nickel constructed from holes formed of the detached hydrogen bubbles and surrounded by cauliflower-like agglomerates of approximately spherical grains (the honeycomb-like structure) were obtained by the galvanostatic regime of electrolysis from the chloride electrolyte. Although crystallites were dominantly oriented in the (111) plane in both Pb and Ni particles, analysis of the XRD data showed different preferred orientation of the formed particles. All types of Pb dendritic particles showed the strong (111) preferred orientation, while crystallites of Ni in the spongy-like particles were almost random oriented. The obtained results were discussed following Winand`s classification of metals on the normal, intermediate and inert metals based on their values of the exchange current density, melting point and overpotential for hydrogen evolution reaction.

Keywords: electrolysis, powder, lead, nickel, SEM, XRD.

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KORELACIJA IZMEĐU ORIJENTACIJE KRISTALA I MORFOLOGIJE ELEKTROLITIČKI  PROIZVEDENIH PRAŠKASTIH ČESTICA: ANALIZA GRANIČNIH SLUČAJEVA

Izvod

Čestice praha olova i nikla proizvedene su procesima elektrolize i okarakterisane skenirajućim elektronskim mikroskopom. Urađena je i rendgenostrukturna analiza dobijenih čestica. Morfologije čestica olova i nikla su korelisane sa njihovom kristalnom strukturom na polukvantitativnom nivou određivanjem “Teksturnog koeficijenta” (TC) i “Relativnog teksturnog koeficijenta” (RTC). Dvodimen­zionalne (2D) dendritične čestice olova različitog stepena razgranatosti dobijene su potenciostatskim režimom elektrolize iz nitratnog, acetatnog i hidroksilnog elektrolita. Čestice nikla sunđerastog oblika u čijoj strukturi se uočavaju rupe formirane odvajanjem mehurova vodonika okružene karfiolastim aglomeratima približno sferičnih zrna (struktura pčelinjeg saća) dobijene su galvanostatskim režimom elektrolize iz hloridnog elektrolita. Premda su kristaliti dominantno orijentisani u (111) ravni i u česticama praha olova i nikla, analiza rendgenograma je pokazala njihove različite dominantne orijentacije. Svi tipovi olovnih dendritičnih čestica su pokazali strogu (111) dominantnu orijentaciju, dok kristaliti nikla u sunđerastim česticama su bili skoro slučajno orijentisani. Dobijeni rezultati su diskuto­vani sledeći Vinjadovu klasifikaciju metala na normalne, intermedijalne i inertne, zasnovane na njihovim vrednostima gustine struje izmene, tačke topljenja i prenapetosti za reakciju izdvajanja vodonika.

Ključne reči: elektroliza, prah, olovo, nikal, skenirajući elektronski mikroskop, rentgeno-strukturna analiza.

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Maja D. Obradović1*, Snežana Lj. Gojković2

1University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Belgrade, Serbia, 2University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:66.097.4/.8(n)
doi:
10.5937/ZasMat1802265O


Zastita Materijala 59 (2)
265 – 272 (2018)

CO tolerant Pt/Ru0.7Ti0.3O2 nanocatalyst for hydrogen oxidation reaction

Abstract

The oxidation of pure H2 and H2/CO mixture (100 ppm CO) was investigated on Pt nanocatalyst supported on Ru0.7Ti0.3O2 (Pt /Ru0.7Ti0.3O2) by linear sweep voltammetry at a rotating disc electrode in 0.1 M HClO4. The results were compared with those on the commercial Pt/C catalyst. It was demonstrated that Pt/Ru0.7Ti0.3O2 electrode possesses good conductivity and stability of the supports in the electrochemical experiments. The onset potential of COads oxidation on Pt/Ru0.7Ti0.3O2 is lower than Pt/C indicating that the Pt nanoparticles are in close contact with Ru atoms from support, which enable bifunctional mechanism and electronic effects to be operable. The influence of the poisoning of Pt/Ru0.7Ti0.3O2 and Pt/C catalyst by COads on the HOR was examined at several surface coverages ranging from 0 to 0.6. The decrease in HOR current on COads poisoned surface in low over-potential region of 0.05-0.50 V is less pronounced on Pt/Ru0.7Ti0.3O2 than on Pt/C. This is ascribed to a weakening of the Pt–CO interaction and consequently higher mobility of COads on Pt particles contacting Ru from the Ru0.7Ti0.3O2 support.

Keywords: platinum, RuO2, TiO2, hydrogen oxidation, CO tolerance.

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Pt/Ru0,7Ti0,3O2 kao nanokatalizator za oksidaciju vodonika i njegova tolerancija Na CO

Izvod

Oksidacija čistog H2 i smeše H2/CO (100 ppm CO) je ispitivana na nanokatalizatoru koji se sastojao od čestica Pt na nosaču Ru0,7Ti0,3O2 (Pt/Ru0,7Ti0,3O2). Korišćene su metoda linearne voltametrije u rastvoru 0,1 M HClO4 i rotirajuća disk elektroda. Rezultati su upoređeni sa komercijalnim katalizatorom Pt/C. Za katalizator Pt/Ru0,7Ti0,3O2 je utvrđena dobra provodnost i stabilnost nosača u elektrohemijskim eksperimentima. Pokazano je da oksidacija adorbovanog CO na Pt/Ru0,7Ti0,3O2 počinje na negativnijim potencijalima nego na Pt/C. To ukazuje da su nanočestice Pt u bliskom kontaktu sa atomima Ru iz nosača, što omogućuje odigravanje bifunkcionalnog mehanizma i ispoljavanje elektronskog efekta. Uticaj trovanja katalizatora Pt/Ru0,7Ti0,3O2 i Pt/C adsorbovanim CO na oksidaciju H2 je ispitivan na nekoliko stepena pokrivenosti u opsegu od 0 do 0,6. Smanjenje struje oksidacije vodonika na površini delimično pokrivenoj adsorbovanim CO u oblasti malih prenapetosti 0,05-0,50 V je manje izraženo na Pt/Ru0,7Ti0,3O2 u odnosu na Pt/C. Ovo se pripisuje slabljenju interakcija Pt–CO što dovodi do povećane pokretljivosti CO na česticama Pt koje su u kontaktu sa Ru iz nosača Ru0,7Ti0,3O2.

Ključne reči: platina, RuO2, TiO2, oksidacija vodonika, tolerancija na CO.

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Nebojša S. Marinković*

Columbia University, Department of Chemical Engineering,
New York, USA

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:620.187./.187
doi: 10.5937/ZasMat1802273M

Zastita Materijala 59 (2)
273 – 281  (2018)

Optimization of in situ infrared spectro-electrochemical accessory with the aid of reflectance and electric field and calculations

Abstract

Optical design of the in situ infrared reflection-absorption spectroscopy (IRRAS) accessory is discussed, with a particular attention to its optimization on the base of theoretical calculations. The sensitivity of this versatile technique applicable to most mono- and polycrystalline electrodes can be greatly enhanced by carefully adjusting the angle of incidence of infrared (IR) beam and the position of the electrode. Using Fresnel equations, we show that the reflectivity and the strength of the electric field of a stratified medium are interconnected, so that the magnitude of the electric field strength can be monitored by the reflectivity of the light into the first layer, and ultimately into the IR detector. The result of calculating these effects for the three-layer system, zinc selenide crystal / aqueous solution / Pt electrode, clearly shows that the intensity of the interferogram in the spectrometer can be used to precisely adjust the angle of incidence of the IRRAS accessory: the interferogram strength is increasing by pressing the Pt electrode on the ZnSe crystal at or near the optimal incident angle and decreasing when the angle of incidence is only a few degrees away from optimal. By combining the results of the calculation of the electric field with an experiment, an optimized system for identifying and tracking various species adsorbed on the surface of the electrode or within a few micrometers from the surface in the solution due to the change in the electrochemical potential can be achieved.

Keywords: ATR, Otto configuration, IRRAS, Electric field, Fresnel equations.

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OPTIMIZACIJA OPTIČKOG DODATKA ZA  In situ  INFRACRVENU SPEKTRO-ELEKTROHEMIJU POMOĆU PRORAČUNA REFLEKTIVNOSTI I ELEKTRIČNOG POLJA

Izvod

Razmatramo optički dizajn dodatka za in situ infracrvenu reflekciono-absorpcionu spektroskopiju (IRRAS), sa posebnom pažnjom na njegovu optimizaciju na osnovu teorijskih proračuna. Osetljivost ove svestrane tehnike primenljive na većinu mono- i polikristalnih elektroda se može značajno povećati pažljivim podešavanjem upadnog ugla infracrveng (IC) zraka i pozicije površine elektrode. Pomoću Frenelovih jednačina pokazali smo da su reflektivnost i jačina električnog polja višeslojnog optičkog sistema medjusobno povezani, tako da se jačina električnog polja može pratiti pomoću refleksije svetlosti u prvi sloj, odnosno u IC detektoru. Rezultat izračunavanja ovih efekata za troslojni sistem, kristal cink selenida / vodeni rastvor / Pt elektroda, pokazuje da se jačina interferograma na infracrvenom spektrometru može uspešno koristiti za precizno podešavanje upadnog ugla dodatka za IRRAS: intenzitet interferograma se povećava pritiskanjem Pt elektrode na kristal ZnSe u blizini optimalnog upadnog ugla svetlosti, a smanjuje kada je upadni ugao svega nekoliko stepeni dalje od optimalnog. Kombinovanjem rezultata proračuna električnog polja sa eksperimentom može se dostići optimizovan sistem za identifikaciju i praćenje raznih vrsta čestica adsorbovanih na površini elektrode ili unutar nekoliko mikrometara od površine u rastvoru, usled promene elektrohemijskog potenicjala.

Ključne reči: ATR, Oto konfiguracija, IRRAS, električno polje, Frenelove jednačine.

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Milica Gvozdenović1,*, Enis Džunuzović1,
Branimir Jugović2, Branimir Grgur1

1University of Belgrade, Faculty of Technology of Metallurgy, Belgrade, Serbia, 2Institute of Technical Sciences Serbian Academy of Science and Arts, Belgrade, Serbia

Review paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:520.197.6
doi: 10.5937/ZasMat1802282G

Zastita Materijala 59 (2)
282 – 292  (2018)

Polyaniline based corrosion inhibitors for conventional organic coatings

Abstract

Corrosion protection using conventional coatings is the most used method. Application of polyaniline (PANI) as an inhibitor in conventional coating is based on its proven and well examined protective nature, with motivation for replacement of hazardous materials used as inhibitors. Experimental procedures for investigation of the influence of PANI in coatings are focused both on evaluation of physical properties of the coatings studied by FTIR, Raman and UV spectroscopy, thermogravimetric analysis, SEM and TEM microcopies, while the protective nature of the coating, applied at the first place on steel, is studied by accelerated corrosion testing using humidity and salt chamber, electrochemical impedance spectroscopy and polarization measurements upon immersion in corrosion media.

Key words: polyaniline, inhibitors, epoxy coatings, alkyd coatings.

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PRIMENA POLIANILINA KAO INHIBITORA KOROZIJE KLASIČNIH ORGANSKIH PREVLAKA 

Izvod

Primena sistema klasičnih organskih prevlaka za zaštitu metala i legura od korozije je najrasprostranjeniji vid zašte. Primena inhibitora korozije na bazi polianilina (PANI) je zasnovana na njegovom eksperimentalno potvrđenom zaštitnom dejstvu. Osnovni motiv za primenu PANI je zamena ekološki neprihvatljivih materijala koji se korite kao inhibitori. Eksperimentalna istraživanja u ovoj oblsti bazirana su na proučavanju fizičkih svojstava prevlaka primenom spektoskopskih tehnika: FTIR, Ramanske spektroskopije i UV spektroskopije, termogravimetrijske analize, SEM i TEM mikroskopija, dok se ispitivanja zaštitnih svojstava prevlaka na baziraju na ubrzanim korozionim testovima primenom slane i vlažne komore, eksperimentima spektroskopije elektrohemijske impedancije i polarizacionim merenjima.

Ključne reči: polianilin, inhibitori, epoksidne prevlake, alkidne prevlake.

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Marija Đošić1, Ana Janković2, Kyong Yop Rhee3, Vesna Mišković-Stanković2,3,*

1Institute for Technology of Nuclear and Other Mineral Raw Materials, Belgrade, Serbia, 2University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia, 3Kyung Hee University, Department of Mechanical Engineering, Yongin, Republic of Korea

Review paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:620.197.5/.6
doi: 10.5937/ZasMat1802293D

Zastita Materijala 59 (2)
293 – 306 (2018)

Graphene reinforced hydroxyapatite biocomposite coatings obtained by electrophoretic deposition on titanium

Abstract

Fast ongoing research of graphene-based nanomaterials reveals that their exceptional properties could be utized for biomedical applications, especially in tissue engineering and drug delivery. Here, we summarized the results obtained on hydroxyapatite based biocomposite coatings produced by electrophoretic deposition on titanium substrate and reinforced by nanosized graphene, as potential candidates for hard tissue implants.

Keywords: electrophoretic deposition, coatings, biocomposites, hydroxyapatite, graphene.

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BIOKOMPOZITNE PREBLAKE HIDROKSIAPATITA OJAČANE GRAFENOM, DOBIJENE ELEKTROFORETSKIM TALOŽENJEM NA TITANU

Izvod

Brzi razvoj istraživanja nanomaterijala koji sadrže grafen otkrio je da se njihova izuzetna svojstva mogu koristiti za biomedicinske primene, posebno u inženjerstvu tkiva i kao nosači lekova. U ovom radu su prikazani rezultati istraživanja biokompozitnih prevlaka na bazi hidroksiapatita koje su dobijene elektroforetskim taloženjem na titanskom supstratu i ojačane nanočestičnim grafenom, kao potencijalnih kandidata za implante koštanog tkiva.

Ključne reči: elektroforetsko taloženje, prevlake, biokompoziti, hidroksiapatit, grafen.

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Senka Gudić1*, Dario Kvrgić1, Ladislav Vrsalović1, Mirko Gojić2

1University of Split, Faculty of Chemistry and Technology,Split, Croatia, 2University of Zagreb, Faculty of Metallurgy, Sisak, Croatia

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:620.193.4
doi: 10.5937/ZasMat1802307G

Zastita Materijala 59 (2)
307 – 315 (2018)

Comparsion of the corrosion behavior of AISI 304, AISI 316L and duplex steel in chloride solution

Abstract

The corrosion behavior of stainless steels (AISI 304, AISI 316L and duplex steel) in NaCl solution was investigated using open circuit potential measurements, cyclic polarization and linear sweep voltammetry measurements. After cyclic polarization measurements electrode surfaces was investigated by light microscope.

Duplex steel have the most noble open circuit potential, the lowest corrosion current density and the largest width of the passive region indicates its highest corrosion resistance. Also, compared to other samples, duplex steel shows the possibility of self-healing of oxide film.

Increasing the concentration of Cl ion, the depassivation potential becomes more negative for all investigated samples. If the potential scan rate increases depassivation potential becomes more positive, meaning that a certain time (induction time) is needed for the pitting occurs after the actual depassivation potential is established. Depassivation potential and pitting corrosion nucleation time of investigated samples increase in order: AISI 304 < AISI 316L < duplex steel.

Light microscopy investigations of samples reveal pits on the surface of AISI 304 and AISI 316L steel while duplex steel surface is almost clear of any corrosion damage.

Keywords: corrosion, stainless steel, polarization, light microscopy.

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USPOREDBA KOROZIJSKOG PONAŠANJA   AISI 304, AISI 316L I DUPLEX ČELIKA U OTPINI KLORIDA 

Izvod

Korozijsko ponašanje različitih vrsta nehrđajućeg čelika (AISI 304, AISI 316L te duplex čelika) u NaCl otopini ispitano je mjerenjem potencijala otvorenog strujnog kruga te primjenom cikličke i linearne polarizacije. Nakon mjerenja cikličkom polarizacijom površine elektroda snimljene su svjetlosnim mikroskopom.

Duplexs čelik pokazuje najpozitivniju vrijednost potencijala otvorenog strujnog kruga, najmanju gustoću korozijske struje i najšire područje pasivacije, što ukazuje na njegovu najveću korozijsku otpornost. Također, u usporedbi s drugim ispitivanim uzorcima, duplex čelik ima sposobnost obnavljanja površinskog oksidnog filma.

S porastom koncentracije kloridnih iona potencijal depasivacije svih ispitivanih uzoraka čelika postaje negativniji. Nadalje, ukoliko se promjena potencijala u pozitivnom smjeru ostvaruje brže, potencijal depasivacije postaje pozitivniji, što znači da je za pojavu pittinga potrebno izvjesno vrijeme (indukcijsko vrijeme) nakon što se uspostavi stvarni potencijal depasivacije. Potencijal depasivacije i vrijeme nukleacije pitting korozije ispitivanih uzoraka raste redom: AISI304 < AISI 316L < duplex čelik. Ispitivanjem uzoraka svjetlosnim mikroskopom uočena su oštećenja na površini AISI 304 i AISI 316L dok je površina duplex čelika gotovo neoštećena korozijom.

Ključne riječi: korozija, nehrđajući čelik, polarizacija, svjetlosna mikroskopija.

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