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Zaštita materijala 4. 2014

ARAMID COMPOSITES IMPREGNATED WITH DIFFERENT REINFORCEMENT: NANOFIBERS, NANOPARTICLES AND NANOTUBES

Vera Obradović, Dušica Stojanović, Aleksandar Kojović, Irena Živković, Vesna Radojević, Petar Uskoković, Radoslav Aleksić

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

ABSTRACT
In this study, the electrospun nanofibers, nanoparticles and nanotubes were used as reinforcement in order to improve mechanical properties of materials for ballistic protection. The samples of polyurethane/p-aramid multiaxial fabric forms (Twaron fabrics and Colon fabrics) were impregnated with poly (vinyl butyral) (PVB) ethanol solution with the different content of reinforcement. Due to the improvement in mechanical, ballistic and impact properties, the surface modification of the fabrics with γ-aminopropyltriethoxysilane (AMEO silane)/ethanol solution was used and silica nanoparticles were modified with AMEO silane. This study is divided into three parts of research: electrospinning process, ballistic testing of the p-aramid composites and impact tester analysis of the Colon composites. The mechanical properties of all the composites were tested by the dynamic mechanical analysis (DMA).

Keywords: p-aramid composites, Silica nanoparticles, Carbon nanotubes, AMEO silane, PVB/SiO2 nanofibers, Ballistic testing, Impact testing

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ARAMIDNI KOMPOZITI IMPREGNISANI SA RAZLIČITIM OJAČANJIMA: NANOVLAKNA, NANOČESTICE I NANOCEVI

 

IZVOD

U ovom istraživanju su se elektrospinovana vlakna, nanočestice i nanocevi koristili kao ojačanja koja bi unapredila mehanička svojstva materijala za balističku zaštitu. Uzorci poliuretan/p-aramidnih multiaksijalnih lamina (Twaron i Kolon lamine) su impregnisani sa poli(vinil butiral)(PVB)/etanol rastvorom sa različitim sadržajem ojačanja. Radi poboljšanja mehaničkih, balističkih i impakt svojstava, modifikovala se površina lamina sa γ-aminopropiltrietoksisilanom (AMEO silan)/etanol rastvorom i koristile su se silika nanočestice modifikovane AMEO silanom. Ovaj rad je podeljen na tri dela istraživanja: proces elektrospininga, balističko testiranje p-aramidnih kompozita i impakt tester analiza Kolon kompozita. Mehanička svojstva svih kompozita su bila testirana pomoću dinamičko mehaničke analize (DMA).

Ključne reči: p-aramidni kompoziti, Silika nanočestice, Ugljenične nanocevi, AMEO silan, PVB/SiO2 nanovlakna, Balističko testiranje, Impakt testiranje

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INHIBITIVE EFFECT OF AZINE AND DIAZINE DERIVATIVES ON THE CORROSION OF 316L SS IN ACIDIC MEDIA

A.S. Fouda1, A.M.El-desoky2, A.A. Keshk3

1El-Mansoura University, Department of Chemistry, Faculty of Science, El-Mansoura,Egypt, 2Chemistry Department, High Institute of Engineering &Technology  New Damietta,Egypt,  3University of Tabuk, Department of Chemistry, Faculty of Science, Tabuk, Saudi Arabia 

ABSRACT

The inhibiting effect of some azine and diazine derivatives on the corrosion of cyclic stressed 316L SS specimens in 3 M HCl in the presence of organic derivatives with concentrations (1×10-6 M – 11×10-6 M) at 30oC was studied using weight loss and  galvanostatic polarization techniques. The inhibition of these derivatives on the uniform corrosion was evaluated by anodic and cathodic polarization curves of  the electrode in the tested media. The examined derivatives exerted an inhibiting action towards corrosion. Polarization studies revealed that these derivatives behave as mixed inhibitors and inhibit corrosion by parallel adsorption on the specimen surface due to the presence of more than one active centre in the inhibitor molecule. The adsorption obeyed Temkin adsorption isotherm. The inhibitor efficiency increases with increasing the concentration of the inhibitor and decreases with increasing the value of the cyclic stress. Addition of  I , Br and SCN ions to the solution containing organic derivatives increases the inhibition efficiency of the system.

Keywords: Organic derivatives; Inhibition; Cyclic stress; Acidic media; 316L SS

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 UTICAJ INHIBITORA DERIVATA AZINA I DIAZINA NA KOROZIJU NERĐAJUĆEG ČELIKA 316 LSS U KISELOJ SREDINI

IZVOD

Inhibitorski efekat nekih derivata azina i diazina na koroziju 316L SS uzoraka u 3 M HCl u prisustvu organskih derivata sa koncentracijama (1 × 10-6 M – 11 × 10-6 M) na 300C je ispitivan  preko gubitka težine i tehnikom galvanske polarizacije. Inhibitorski efekat ovih derivata na ravnomernost korozije uzoraka je ocenjivan preko anodnih i katodnih polarizacionih krivih elektrode u testiranim medijima. Ispitivani derivati vršili su inhibiciju korozije ispitivanih uzoraka. Polarizaciona ispitivanja su pokazala da se ovi derivati ponašaju kao mešani inhibitori i inhibiraju koroziju adsorpcijom čestica inhibitora na površini uzorka zbog prisustva više od jednog aktivnog centar u molekulima inhibitora. Adsorpcija se ponaša prema Temkinovoj adsorpcionoj izotermi. Dodavanjem I, BR i SCN jona u rastvor koji sadrži organske derivate povećava se efikasnost inhibicije sistema.

Ključne reči: Organski derivati; Inhibicija; Ciklični stres; kisela sredina; nerđajući čelik 316L SS

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PHYSICO-MECHANICAL PROPERTIES CHANGES IN VIRGIN AND RECYCLED POLYETHYLENE FIBERS DURING RECYCLING PROCESS

ELDI LIÇO1, JOZEFITA MARKU1, ELIAS CHATZHITHEODORIDIS2

1University of Tirana , Department of industrial chemistry, Faculty of natural sciences, Tirana, Albania, 2National technical University of Athens, School of mining and metalurginal engineering, Athens, Greece 

ABSTRACT

The aim of this work is to study the changes of physico-mechanical properties of polyethylene during recycling stages. All raw materials were taken virgin and recycled polyethylene granules used for producing plastic bags. Initially they were identified with the vibration spectroscopy FT-IR and Raman, which marked the presence of additives in recycled samples. As recycling process was used as a micro-pilot system; comprising the melt flow index device and a universal mill grinding. Among mechanical properties that were identified were density, specific gravity, melt flow index, yield strength and elasticity modulus and tensile strength. From the results analysis were observed changes in physical and mechanical properties for polyethylene samples by recycling cycles.

Key words: physic-mechanical properties, virgin and recycled polyethylene, vibration spectroscopy

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PROMENE FIZIKO-MEHANIČKIH SVOJSTAVA SVEŽIH I RECIKLIRANIH
POLIETILENSKIH VLAKANA

IZVOD

Cilj ovog rada je bio da se prouče promene fizičko-mehaničkih svojstava polietilena tokom faza reciklaže. Za ispitivanja su uzete čiste i reciklirane polietilenske granule, koje se koriste za proizvodnju plastičnih kesa.  U početku su uzorci bili ispitani pomoću spektroskopije FTIR i Raman, čime je ustanovljeno prisustvo aditiva u recikliranim uzorcima.  Proces reciklaže je korišćen kao mikro-pilot sistem; sadrži uređaj za protok i univerzalni mlin . Među mehaničkim osobinama, koje su identifikovane, su gustina, specifična težina, topivi indeks protoka, tečenje i modul elastičnosti i zatezna čvrstoća. Iz analize rezultata su primećene promene fizičkih i mehaničkih svojstava za reciklirane uzorke polietilenska.
Ključne reči: fizičko-mehanička svojstva, sveži i reciklirani polietilen, spektroskopija

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DESIGN OF GLASS/PHENOLIC BALLISTIC COMPOSITES BY IMPLEMENTATION OF FACTORIAL EXPERIMENTAL DESIGN

 Dimko Dimeski, Vineta Srebrenkoska

University “Goce Delčev“, Faculty of Technology, Štip, R. Macedonia

ABSTRACT

The purpose of the study is to assess the applicability of full factorial experimental design in predicting the ballistic strength of glass fiber/phenolic ballistic composites. In the study we used a number of ballistic composites (20 cm x 20 cm) with different thickness and fiber/resin ratio. The composites were made by an open mold high pressure, high-temperature compression of prepreg layers made of plain woven glass fiber fabric and polyvinyl butyral modified phenolic resin.

The preparation of the composite experimental samples was done in accordance to 22 full factorial experimental design. The areal weight of composites is taken to be the first factor and the second – fiber/resin ratio. The first factor low and high levels are 2 kg/m2 and 9 kg/m2, respectfully and for the second factor – 80/20 and 50/50, respectfully. We used the first-order linear model with interaction to approximate the response i.e. the ballistic strength of the composites within the study domain (2 – 9) kg/m2 x (80/20 – 50/50) fiber/resin ratio. The influence of each individual factor to the response function is established, as well as the influence of the interaction of the two factors. We found out that the estimated first-degree regression equation with interaction gives a very good approximation of the experimental results of the ballistic strength of composites within the study domain.

Key word: glass fiber, ballistic, factorial design, regression equation, V50

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 DIZAJN STAKLO/FENOLNIH BALISTČKIH KOMPOZITA PRIMENOM FAKTORNOG PLANA EKSPERIMENTA

IZVOD

Cilj istraživanja je proceniti aplikativnost punog faktornog dizajna eksperimenata u predviđanju balističke ćvrstoće staklena vlakna/fenolna smola balističkih kompozita. U eksperimentu je korišćeno više kompozita (20cm x 20cm) sa različnom debljinom i različnim odnosom vlakna/smola. Kompoziti su izrađeni u otvorenom kalupu presovanjem slojeva preprega na visokoj temperaturi. Prepreg je na bazi staklene tkanine platnenog prepletaja i fenolne smole modifikovane polivinil butiralom.

Priprema uzoraka je bila u skladu 22 punog faktornog dizajna eksperimenata. Površinska masa kompozita je uzeta kao prvi faktot, a drugi – odnos vlakna/smola. Donje i gornje nivo prvog faktora su 2 kg/m2 and 9 kg/m2, a drugog – 80/20 i 50/50. Koristili smo linerni model prvog reda sa interakcijom da bi aproksimirali odziv t.j. balističku čvrstoću kompozita u istraživačkom domenu (2 – 9) kg/m2 x (80/20 – 50/50). Određen je uticaj svakog pojedinačnog faktora na funkciju odziva kao i uticaj interakcije među faktorima. Nadjeno je da proračunska regresiona jednačina prvog reda sa interakcijom daje veoma dobro predviđanje eksperimentalnih rezultata balističke čvrstoće kompozita u istraživačkom domenu.

Ključne reči: stakleno vlakno, balistički kompoziti, faktorni plan, regresiona jednačina, V50

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 THE INFLUENCE OF INDIUM, GALLIUM AND BISMUTH ON THE CORROSION BEHAVIOR OF ALLOYS INTENDED FOR PROTECTORS

UTICAJ INDIJUMA, GALIJUMA I BIZMUTA NA KOROZIONO PONAŠANJE
LEGURA NAMENJENIH ZA PROTEKTORE

 Jelena Pjescic, Dragan Radonjic, Darko Vuksanovic, Caslav Lacnjevac

1University of Montenegro, Metallurgy and Technology Faculty, Montenegro

2 University of Belgrade, Faculty of Agriculture, Belgrade, Serbia

 

ABSTRACT

This work was carried out of behavior of Al-Zn alloy systems in chloride solutions of different concentrations, with additional alloying indium, gallium and bismuth as micro alloying elements. In addition to these elements is done by the alloying with tin.

Thus obtained aluminum alloy with additional corrosion and electrochemical tests give a chance to produce their own sacrificial electrodes.

In preparing the concept on which this paper is based, started from the fact that there are a number of influential factors, starting from the chemical composition, methods of melting, alloying and casting methods that would allow obtaining high-quality alloy that can be effectively used as a protector.

Key words: corrosion, protectors, alloys

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IZVOD

U ovom radu je izvršeno ispitivanje ponašanja Al-Yn legura u rastvorima hlorida različitih koncentracija, uz dodatak legirajućih mikro elemenata indijuma, galijuma i bizmuta. Pored ovih elemenata vršilo se legiranje i sa kalajem.

Tako dobijene legure aluminijuma su ispitivane na dodatne korozione i elektrohemijske testove kako bi se videla mogućnost proizvodnje žrtvenih elektroda.

U pripremi postupka na kome bi se baziralo ovo, polazi se od činjenice da postoji veliki broj uticajnih faktora, počev od hemijskog sastava, postupka topljenja, legurajuće i livene metode, koje bi omogućile dobijanje visoko kvalitetnih legura koje mogu da se efikasno koriste kao protektori.

Ključne reči: korozija, protektori, legure

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CORROSION PROPERTIES OF AN ALUMINIUM ALLOY 7000 SERIES AFTER A NEW TWO STEP PRECIPITATION HARDENING

 Bore Jegdić1, Biljana Bobić1, Bojan Gligorijević2, Vesna Mišković-Stanković3

1University of Belgrade,Institute for Chemistry, Technology and Metallurgy,  Belgrade,

2University of Belgrade,Innovation center, Faculty of Technology and Metallurgy,

 Belgrade, 3University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia

ABSTRACT

Corrosion properties of an aluminium alloy 7000 series were investigated by different electrochemical methods. The alloy was subjected to the one-step and to a new two-step precipitation hardening. Polarization measurements in the 3.5 wt. % NaCl solution have shown a more positive value of the pitting potential (Epit) and a higher corrosion resistance for the two-step aged alloy. The electrochemical impedance spectroscopy (EIS) has also shown that the two-step aged alloy has better corrosion properties (higher value of polarization resistance, Rp, and lower value of double-layer capacitance, Cdl) comparing to the one-step aged alloy.

Keywords: aluminium alloys, precipitation hardening, corrosion, electrochemical methods

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OTPORNOST PREMA KOROZIJI ALUMINIJUMSKE LEGURE SERIJE 7000 POSLE NOVOG DVOSTEPENOG TERMIČKOG TALOŽENJA

IZVOD

Otpornost prema koroziji aluminijumske legure serije 7000 ispitivana je primenom različitih elektrohemijskih metoda. Legura je bila podvrgnuta jednostepenom i novom dvostepenom termičkom taloženju. Polarizaciona merenja u 3,5 mas.% NaCl su pokazala da legura posle dvostepenog termičkog taloženja ima pozitivniju vrednost potencijala pitinga (Epit) i veću otpornost prema koroziji. Spektroskopija elektrohemijske impedancije (SEI) je takođe pokazala da legura posle dvostepenog termičkog taloženja ima bolju otpornost prema koroziji (veću vrednost polarizacione otpornosti, Rp i manju vrednost kapacitivnosti dvojnog sloja, Cdl) u poređenju sa legurom posle jednostepenog termičkog taloženja.

Ključne reči: aluminijumske legure, termičko taloženje, korozija, elektrohemijske metode

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TIME – TEMPERATURE  SUPERPOSITION PRINCIPLE – APPLICATION OF  WLF EQUATION IN POLYMER ANALYSIS AND COMPOSITES

Darko Ljubić1, Marina Stamenović2, Chad Smithson1, Maja Nujkić3,
Bojan Međo4, Slaviša Putić4

1McMaster University, Hamilton, Department of chemical engineering, Hamilton, ON, Canada; 2College of vocational studies Belgrade Polytechnic, Belgrade, Serbia; 3University in Belgrade,Technical Faculty in Bor,  Bor, Serbia; 4University of Belgrade, Faculty of Technology and Metallurgy,  Belgrade, Serbia

ABSTRACT

Polymers are the most studied viscoelastic material. The shorter times (high frequencies) corresponding to lower temperatures and long times (low frequencies) to high temperatures. This represents the quantitatively applied time-temperature superposition (TTS). Use of the Williams-Landel-Ferry (WLF) equation and the time-temperature superposition principle enables prediction and modeling of the mechanical and rheological properties of polymeric systems outside the timescale of the experiment. Application and validity of the TTS principle and WLF equation in polymer blends, composites, biopolymers and polymer networks will be discussed in this review.

Key words: TTS principle, WLF equation, application, polymers, composites, characterization

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PRIMCIP SUPERPONIRANJA VREMENA I TEMPERATURE – PRIMENA WLF JEDNACINE ZA ISPITIVANJE POLIMERA I KOMPOZITA 

 

IZVOD

Polimeri su najproučavaniji viskoelastični materijali. Kraće vreme (odnosno visoke frekvencije) odgovaraju nižim temperaturama, a duže vreme (odnosno niske frekvencije) odgovaraju visokim temperaturama. Ovaj odnos vremena (frekvencije) i temperature predstavlja kvantitativnu primenu principa superponiranja vremena i temperature (TTS). Upotreba Viliams-Lendl-Feri (Williams-Landel-Ferry, WLF) jednačine i principa superponirnaja vremena i temperature omogućava predviđanje i modelovanje mehaničkih i reoloških svojstava polimernih sistema izvan vremenske skale eksperimenta. Upotreba i validnost TTS i WLF jednačine na polimerne blende, kompozite, biopolimere i polimerne mreže biće predstavljeni i razmatrani u ovom radu.

Ključne reči: TTS princip, WLF jednačina, primena, polimeri, kompoziti, karakterisanje

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Primena lasera u čišćenju korozije na starim tekstilnim predmetima sa metalnim vezama

SLАVICА RISTIĆ1, DАNIJELKА RАDOVАNOVIĆ2, SUZАNА POLIĆ3,
SLOBODAN DRAGUTINOVIĆ2, JOAKIM STRIBER3

1Institut Gošа, Beogrаd; 2Etnogrаfski muzej u Beogrаdu, Beogrаd;  3Centrаlni institut zа konzervаciju u Beogrаdu, Beograd, Srbija

 

IZVOD

Klаsične metode čišćenjа starih tekstilnih predmeta sа metаlnim nitimа često puta ne dаje očekivаne rezultаte. Primenа lаserа u zaštiti i konzervaciji predmetа kulturne bаštine poslednjih godinа ima veliku ulogu. Nаjkomplikovаnijа je primenа lаserа u čišćenju eksponаtа koji imаju višekomponentni sаstаv, kаo što su, kombinаcije metаl-tekstil. U rаdu se razmatra problem koji se pojavio u fundusu tekstila Etnografskog muzeja u Beogradu. Prikаzаni su rezultаti ispitivаnjа efekаtа lаserskog čišćenjа na eksperimentalnim uzorcima etnografskog tekstila sа metаlnim nitimа. korišćenjem Nd:Yag lаsera. Ispitivаnje efekаtа čišćenja je vršeno optičkom i skenirаjućom elektonskom mikroskopijom i EDX аnаlizom. Određeni su pаrаmetri zа uspešno i bezbedno čišćenje korozionih produkаtа nа metаlnim nitimа, nа izabranim eksponatima.

Ključne reči: Lаsersko čišćenje, Nd:YAG lаser, korozijа, metаlne niti, tekstil

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APPLICATION OF LASERS FOR CORROSION CLEANING OF ANCIENT TEXTILES WITH  METALLIC THREADS

ABSTRACT

Classical methods of corrosion cleaning of ancient textiles with metallic threads often do not produce the expected results. The use of lasers in the protection and conservation of cultural heritage items in recent years has an important role. The most complicated is the use of lasers in cleaning items that have a multicomponent structure, such as, combination of metal and fabric. This paper discusses the problem that appeared in the holdings of textiles Ethnographic Museum in Belgrade. We presents the results of the effects of Nd:Yag laser cleaning of ethnographic textile experimental samples with metallic threads. Cleaning effects was investigated by an optical and scanning electronic microscopy (OM and SEM) and EDX analysis. Parameters for successful and safe cleaning of corrosion products on the metal threads were determined for some exponats.

Key words: Laser cleaning, Nd:Yag laser, corrosion, metallic threads, textile

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THERMAL TREATMENT OF SEWAGE SLUDGE – ONE OF POSSIBLE DISPOSAL METHODS

Filip Kokalj and Niko Samec

University of Maribor, Faculty of Mechanical Engineering, Maribor, Slovenia

ABSTRACT

Waste water treatment is a standard process in developed countries. It is intended to minimize the influence of waste water on the environment.

The treatment process produces various remains that are generally called sewage sludge. In general, the remaining material is treated physically to dewater the sludge to reduce the volume and mass before disposal. This treated sewage sludge has around 25% of dry solids.

The chemical and physical properties of the sewage sludge have to be monitored to determine the correct method of disposal. If the sewage sludge contains higher concentrations of heavy metals the only method for the disposal is thermal treatment.

This article will present possible technologies for sewage sludge thermal treatment and the experience of Slovene waste thermal treatment plant that incinerates sewage sludge.

Key words: waste water treatment, sewage sludge, heavy metals, waste incineration, disposal

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 TERMIČKI TRETMAN KANALIZACIONOG MULJA – JEDAN OD MOGUĆIH METODA ODSTRANJIVANJA 

IZVOD

Prečišćavanje otpadnih voda je standardni proces u razvijenim zemljama. Namera je da se minimizira uticaj otpadnih voda na životnu sredinu . Ovaj proces tretmana proizvodi razne ostatke koji se uglavnom nazivaju muljem. Generalno, preostali materijal se fizički tretira da bi se smanjila zapremina i masa mulja pre odlaganja. Tako tretirani mulj ima oko 25% suve materije . Hemijske i fizičke osobine mulja se moraju pratiti da bi se mogao utvrditi prihvatljiv metod odstranjivanja . Ako mulj sadrži veće koncentracije teških metala jedini metod za odstranjivanje je termički tretman. Ovaj članak će predstaviti moguće tehnologije za termički tretman mulja i iskustvo slovenačkog objekta za termički tretmana otpada, koji spaljuje mulj.

Ključne reči: prečišćavanje otpadnih voda, kanalizacioni mulj, teški metali, spaljivanje otpada, odstranjivanje

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Mehanohemijsko-termički postupak dobijanja maskirnog pigmenta

 

MILAN PETROV, MIROSLAV SOKIĆ, ZVONKO GULIŠIJA,
VLADISLAV MATKOVIĆ, LJUBIŠA ANDRIĆ, JOVICA STOJANOVIĆ

Institut za tehnologiju nuklearnih i drugih mineralnih sirovina, Beograd, Srbija

IZVOD

U ovom radu je ispitivana mogućnost dobijanja maskirnog pigmenta mehanohemijsko termičkim postupkom kao i energetsko učešće mehanohemijskog tretmana u dobijanju maskirnog pigmenta stehiometrijske formule Co0,51Zn0,29Mg0,41Cr1,24Al0,24Ti0,31O4. Mehanohemijski i termički tretirani uzorci smeše oksida radi dobijanja kompleksnog spinela su eksperimentalno istraživani u više serija opita, pri čemu su menjani parametri vezani za rad visokoenergetskog vibracionog mehanoaktivatora. Mehanohemijskom aktivacijom smeše oksida (Cr2O3, CO-oksida, ZnO, TiO2, MgO i Al2O3), u vibracionom mehanoaktivatoru sa prstenovima od 30; 60 i 90 min, a zatim termičkim tretiranjem u elektrootpornoj peći, pri vremenu zadržavanja uzorka od 1h, dobija se materijal spinelne strukture koji je pogodan kao maskirni pigment u vojnoj industriji.

Ključne reči: spinel, mehanohemijska aktivacija, vibracioni mehanoaktivator, žarenje

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MECHANOCHEMICAL-THERMAL PROCESS OF OBTAINING MASKING PIGMENT

ABSRACT

In this paper the possibility of obtaining masking pigment mechanochemically thermal process and the energy share of mechanochemical treatment in obtaining masking pigment by stoichiometric formula (Co 0.51 Zn 0.29 Mg 0.41 Cr 1.24 Al 0.24 Ti 0, 31 O 4).Mechanochemical and heat treated samples to obtain a mixture oxide spinel complex were experimentally investigated in a series of experiments wherein the altered parameters related to the operation of high energy vibratory mechanoactivator. Mechanochemical activation mixture oxide (Cr2O 3, C-O oxide, ZnO, TiO 2, MgO and Al 2 O 3), in vibration mechanoactivator with rings of 30; 60 and 90 min, and then, heat treatment in an electric furnace, with the sample retention time of 1 hour, the material is obtained, which spinel structure is suitable as the pigment in the masking military industry.

Key words: spinel, mechanochemical activation, vibrating mechanoactivator

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DEJSTVO HIPERPLASTIFIKATORA NA BETON

Gordana Broćeta1, Danijela Đurić-Mijović2, Milka Škrbić3

 1Univerziteta u Banjaluci, Arhitektonsko-građevinski fakultet,  Banja Luka, R.Srpska; 2Univerziteta u Nišu, Građevinsko-arhitektonski fakultet, Niš, Srbija; 3Zavod za izgradnju a.d., Banja Luka, R.Srpska

IZVOD 

U radu se prikazuje mogućnost modeliranja svojstava betona u svježem i/ili očvrslom stanju primjenom hemijskih dodataka tipa hiperplastifikatora, baziranih na modifikovanom polikarboksilik-eter polimeru. Daje se pregled njihovih primjena u sopstvenim i drugim eksperimentalnim istraživanjima, sa iskustvima o količinama i načinu primjene, mehanizmu djelovanja, kombinaciji sa drugim hemijskim dodacima i uticaju na ostale komponentne materijale. Rezultati ispitivanja pokazuju mogućost ostvarenja visokog nivoa pokretljivosti svježeg betona (bez pojava izdvajanja vode i/ili segregacije agregata), modifikaciju pora u cementnom kamenu, povećanje čvrstoće pri pritisku – što konačno povoljno utiče na trajnost betona.

Ključne riječi: hemijski dodatak, hiperplastifikator, hidratacija cementa, beton, pore, eksperimentalni rezultati

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THE INFLUENCE OF HYPERPLASTICIZER ON CONCRETE

ABSTRACT

The paper presents the possibility of modeling of concrete properties in fresh and/or hardened state by applying hyperplasticizers type admixtures, based on a modified polycarboxyl ether polymer. It provides an overview of its application in their own and other experimental surveys with the experiences of the amount and mode of administration, mechanism of action, combination with other admixtures and the impact on other component materials. The test results demonstrate the possibility of achieving a high level of flowability of fresh concrete (absence of bleeding and/or segregation), a modification of the pores in cement matrix, an increase of compressive strength – wich further increases the durability of concrete.

Key words: admixture, hyperplasticizer, cement hydration, concrete, pores, experimental results

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UTICAJ HLORIDNIH JONA NA ELEKTROHEMIJSKU OKSIDACIJU CIJANIDA
U OTPADNIM VODAMA

 Borislav N. Malinović1, Miomir G. Pavlović2, Nebojša Gorgi1

1Univerzitet u Banjoj Luci, Tehnološki fakultet, Banja Luka, R. Srpska

2Univerzitet u Beogradu, IHTM-CEH, Beograd, Srbija

IZVOD

U radu je prikazan uticaj hloridnih jona na elektrohemijsku oksidaciju cijanida iz otpadnih voda. Hloridni joni su dodavani u obliku NaCl (c=0,017 mol/L), a elektrohemijska oksidacija je vršena u laboratorijskom elektrohemijskom reaktoru sa elektrodama od čelika i nerđajućeg čelika (j=10 mA/cm2, t=90 min.). Pri navedenim uslovima efikasnost uklanjanja cijanida na čeličnim elektrodama je bila Eu=91,5%, a sa elektrodama od nerđajućeg čelika Eu=99,5%.

 

Ključne riječi: elektrolitička degradacija, otpadne vode, cijanidi, pomoćni elektrolit.

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 EFFECT OF SUPPORTING ELECTROLYTE ON ELECTROLYTIC DEGRADATION OF CYANIDE WASTEWATER

ABSTRACT

The paper describes the influence of chloride ions on the electrochemical oxidation of cyanide from wastewater. Chloride ions are added in the form of NaCl (c=0,017 mol/L), and electrochemical oxidation is carried out in a laboratory electrochemical reactor with electrodes made ​​of steel and stainless steel (j=10 mA/cm2, t=90 min.). In these conditions the removal efficiency of cyanide on steel electrodes was Eu = 91.5%, and with electrodes made ​​of stainless steel Eu = 99.5%.

Key words: electrolytic degradation, waste water, cyanides, supporting electrolyte.

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STRATEGIJA BILJAKA U BORBI PROTIV FITOTOKSIČNIH KONCENTRACIJA METALA KAO KLJUČNI PEDUSLOV USPEŠNE FITOREMEDIJACIJE: EKSKLUDERI I HIPERAKUMULATORI, deo II

Alagić Č. Slađana, Nujkić M. Maja, Dimitrijević D. Mile

Univerzitet u Beogradu, Tehnički fakultet u Boru, Bor, Srbija

IZVOD

Biljke raspolažu čitavim nizom mehanizama koji se mogu aktivirati u procesima detoksifikacije i tolerancije prema stresu izazvanom teškim metalima. Najuspešnije mehanizme razvile su neke specifične biljne vrste, poznate kao biljke hiperakumulatori, koje mogu da akumuliraju enormno visoke koncentracije ovih opasnih polutanata u svojim nadzemnim organima. Ovo je strategija koja je dalje zgodno iskorišćena u svrhe fitoremedijacije kao relativno nove, ali ekonomski i ekološki krajnje prihvatljive tehnologije za remedijaciju kontaminiranih zemljišta i voda.

Ključne reči: teški metali, ekskluderi, hiperakumulatori, fitoremedijacija

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 PLANTS STRATEGIES AGAINST METAL PHYTOTOXICITY AS A KEY PREREQUISITE FOR AN EFFECTIVE PHYTOREMEDIATION: EXCLUDERS AND HYPERACCUMULATORS, part II 

ABSTRACT

Plants have a wide range of mechanisms which can be activated in the processes of heavy metal detoxification and tolerance. The most successful mechanisms have been developed by specific plant species, known as hyperaccumulators, which may accumulate enormous concentrations of these dangerous pollutants in their above ground parts. This is a strategy which was efficiently exploited for phytoremediation purposes, as a relatively new, but economically and environmentaly highly sufficient technology for the soil and water remediation.

Key words: heavy metals, excluders, hyperaccumulators, phytoremediation

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MINERALOGICAL INVESTIGATIONS IN METALLURGY AS A CONTRIBUTION TO THE AFIRMATION OF INDUSTRIAL MINERALOGY IN SERBIA

SNEŽANA DEVIĆ1, MIRA  COCIĆ2

1Institut IMS a.d., Belgrade; 2University of Belgrade, Tehnički fakultet u Boru, Bor, Serbia

ABSRACT

Industrial mineralogy is a part of mineralogy dealing with natural and synthetic minerals, raw materials, secondary raw materials, polymineral materials that originated from the production processes, etc. As applicable, it has been used in the refractories industry, ceramics industry, ferrous and non-ferrous metallurgy, cement industry and other industries. The work aimed at presenting its contribution to the affirmation of industrial mineralogy in Serbia through the results of mineralogical investigations obtained in ferrous metallurgy and copper metallurgy. A larger number of mineralogical investigations, carried out on the materials being characteristic for metallurgical processes and issues of ferrous metallurgy and copper metallurgy, have been stated in this work. Refractory bricks, various types of slag, final flotation waste, copper concentrate, etc. have been investigated. At the same time, the reasons and objectives of performed mineralogical investigations have been given. The results of mineralogical investigations have been shown in detail on two examples. The first are associated with the problems and material in ferrous metallurgy and the second with the material and problems in copper metallurgy. Firstly, the results of mineralogical investigations of casting powders have been shown. They have been investigated for verification of the quality and erosion of the alumographite entry nozzles, that occurred due to their effect. The investigations aimed at increasing the durability (resistance) of the alumographite entry nozzles being utilized in the process of continuous casting of steel. By increasing the durability of entry nozzles the production costs are reduced. The method of X-ray diffraction analysis (XRPD) has been used for investigating the mineralogical composition of casting powders. The results of studying the process of copper concentrate roasting in the fluo-solid reactor have been shown in the second example, with the aim of investigating the transformation degree of the primary ore minerals under various technological parameters.The input material (charge) and roasting products in the reactor (calcine) were investigated by various methods.The investigation results have shown that reactions of mineral transformations are not completed, i.e. they are developing only partially (12-22%), which is the consequence of insufficiently long heating, unsuitable temperature or unfulfilled other parameters, such as for example, a non-uniform grain size. All stated mineralogical investigations and the results shown in this work gave a significant contribution to the affirmation of industrial mineralogy in Serbia.

Keywords: Mineralogical investigations, Metallurgy, Industrial mineralogy

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MINERALOŠKA ISPITIVANJA U METALURGIJI  KAO DOPRINOS AFIRMACIJI INDUSTRIJSKE MINERALOGIJE SRBIJE

IZVOD

Industrijska mineralogija predstavlja deo mineralogije koja se bavi  prirodnim i sintetičkim mineralima, sirovinama, sekundarnim sirovinama, polimineralnim materijalima, koji su nastali u procesima proizvodnje. Kao aplikativna ona je našla svoje mesto u vatrostalnoj industriji, keramičkoj industriji, crnoj i obojenoj metalurgiji, cementnoj industriji i drugim industrijama. Rad ima za cilj da kroz rezultate mineraloških ispitivanaja dobijenih u crnoj metalurgiji i metalurgiji bakra pokaže njihov doprinos afirmaciji industrijske mineralogije Srbije. U radu je naveden veći broj mineraloških ispitivanja obavljenih na materijalima koji su karakteristični za metalurške procese i problematiku crne metalurgije i metalurgije bakra. Ispitivane su vatrostalne opeke, različite troske, definitivna flotacijska jalovina, koncentrat bakra, itd. Istovremeno su dati razlozi i ciljevi obavljenih mineraloških ispitivanju. Detaljno, na dva primera,  prikazani su rezultati mineraloških ispitivanja. Jedni su vezani za problematiku i materijal u crnoj metalurgiji, a drugi za materijal i problematiku u metalurgiji bakra. Prvim su prikazani rezultati mineraloških ispitivanja livnih prahova. Ispitani su radi provere kvaliteta i erozije alumografitnih izlivnika nastale usled njihovog dejstva.  Ispitivanja su imala za cilj povećanje trajnosti (izdržljivosti) alumografitih izlivnika koji se koriste u procesu kontinuiranog livenja čelika. Povećanjem trajnosti izlivnika smanjuju se troškovi proizvodnje. Za ispitivanje mineraloškog sastav livnih prahova korišćena je metoda  rendgensko difrakcione analize (XRPD). U drugom primeru prikazani su rezultati proučavanja procesa prženja koncetrata bakra u fluo-solid reaktoru sa ciljem da se ispita stepen transformacije primarnih rudnih minerala pod različitim tehnološkim parametrima.Ulazni materijal (šarža) i produkti prženja u reaktoru (poletina) ispitivani su različitim metodama. Rezultati ispitivanja su pokazali da reakcije transformacija minerala nisu potpune tj. odvijaju se samo delimično (12-22%); što je posledica nedovoljno dugog zagrevanja, neodgovarajuće temperature ili neispunjenosti drugih parametara kao što je npr. neujednačena veličina zrna. Sva navedena mineraloška ispitivanja i rezultati prikazani u ovom radu dali su značajan doprinos afirmaciji Industrijske mineralogije Srbije.

Ključne reči: Mineraloška ispitivanja, Industrijska mineralogija, metalurgija

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THE FACTORS DETERMINING THE SERVICE LENGHT OF THE LEAD REFINING KETTLES 

BRANISLAV NIKOLIĆ, SVETLANA NIKOLIĆ,VESNA VUJAČIĆ

ABSTRACT

Continuous process, as well as refining capacity of lead is highly dependent on the quality of kettles for refining lead. The kettles are made from special kettles plate and are generally spherical in shape. Quality kettle plate, the method of construction of the kettle, the kettle operation mode, proper maintenance regime technological refining process is represented by factors of which depends on the overall lifetime of the kettle. The quality of the welding electrode and method significantly influences the lifetime of the kettle, not only in the preparation of the kettle, but also in its reparation.

Keywords: lead refining, kettle,construction,exploitation, life time.

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FAKTORI KOJI ODREĐUJU RADNI VEK KOTLOVA ZA RAFINACIJU OLOVA

IZVOD

Kontinualni proces, kao i kapacitet rafinacije olova veoma zavisi od kvaliteta kotlova za rafinaciju olova. Kotlovi se izrađuju od specijalnog kotlovskog lima i uglavnom su sfernog oblika.

Kvalitet kotlovskog lima, način konstrukcije kotla, način eksploatacije kotla, pravilno održavanje režima tehnološkog procesa rafinacije predstvaljaju faktore od kojih zavisi ukupni radni vek kotla. Način zavarivanja i kvalitet elektroda bitno utiču na radni vek kotla, ne samo pri izradi kotla, nego i pri njegovoj reparaciji.

Ključne reči: rafinacija olova, kotao, konstrukcija, eksploatacija, radni vek.

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