Alkali-silica expansion potentiality of Erzeni riverbed aggregates (Albania) and the risk of corrosion
in concretes produced with them
JOZEFITA MARKU
Department of Industrial Chemistry, Faculty of Natural Sciences, Tirana, Albania
Abstract
The environmental and fuel efficiency reasons led the industry of building raw materials to develop new technologies for production of cements. The cements being produced have high alkali content which in combination with some sorts of aggregates may influence the chemistry of the concrete mixture that may cause long term harmful effects to concrete structures.
In this paper it is succinctly reviewed a part of scientific research work done on the possibility of the manifestation of the harmful effects caused by Alkali-Silica Reaction (ASR) on concretes made of high alkali cements and riverbed aggregates of Albania, in particular of those of Erzeni River, which is the most exploited one in Albania. The treatment of this topic has been a necessity and is considered very important for building industry in Albania, where traditionally low alkali cements have been produced and used. Especially in the period of transition, when high alkali cements started to be used both from import and domestic production, it is considered very important the study of the suitability of the riverbed aggregates in concrete produced with high alkali content cement since there are no ways of preventing ASR after the concrete has been placed.
The results and recommendations of this study serve to increase the builder’s awareness of the need of proper investigation, from this point of view, of the raw materials prior to construction. They also contribute to environment protection both by recommending alternative aggregates to riverbed ones and by helping to avoid the degradation, in timeframe, of concrete structures.
Keywords: Alkali-Silica Reaction (ASR), riverbed aggregates, chert, siliceous aggregate, limestone aggregate.
ALKALNO-SILIKATNI AGREGATI IZ KORITA REKE ERZENI (ALBANIJA) I MOGUĆNOST NASTANKA KOROZIJE U BETONU PROIZVEDENOG OD NJIH
IZVOD
Razlozi ekološke efikasnosti i cena goriva vodio je industriju građevinskih sirovina da razvijaju nove tehnologije za proizvodnju cementa. Ovi cementi, koji se proizvode, imaju visok sadržaj alkalija, koji u kombinaciji sa nekim vrstama agregata mogu uticati na hemijski sastav vode za betonsku mešavinu, koja može uzrokovati dugoročne štetne efekte na betonskim konstrukcijama.
U ovom radu je sažeto pregledan deo naučno-istraživačkih ispitivanja obavljen na mogućnosti ispoljavanja štetnih efekata izazvanih alkalno – silikatnih reakcija ( ASR) u betonu napravljenog od visoko alkalnih cementa i agregata iz korita reka u Albaniji, posebno onih agregata iz reke Erzeni, koji su najviše eksploatisani u Albaniji. Tretman ove teme je bio nužnost i veoma važan za građevinarstvo u Albaniji, gde se proizvedi do polovne količina tradicionalno niskih alkalnih cementa. Posebno u periodu tranzicije, kada su visoko alkalni cementi počeli da se koristi i iz uvoza i iz domaće proizvodnje, smatra se veoma važnim proučavanje podobnosti korišćenja agregata iz reka u betonu proizvedenih sa visokim sadržajem alkalnog cementa, jer ne postoje načini sprečavanje ASR ako konkretno nije postavljen.
Rezultati i preporuke ovih ispitivanja služe da se poveća svest graditelja da je potrebno pravilno istražiti, sa ove tačke gledišta, sve sirovine pre izgradnje objekta. Oni, takođe, doprinose zaštiti životne sredine i predlažući alternativne agregate iz korita reke pomažu i da se izbegne propadanje, u roku, betonskih konstrukcija.
Ključne reči: alkalno – silicijumska reakcija (ASR), rečni agregati, silikatni agregat, krečnjački agregati.
Elektrohemijske osobine bakra i legura bakra
kao biomaterijala
ŽAKLINA TASIĆ, MILAN ANTONIJEVIĆ
Univerzitet u Beogradu, Tehnicki fakultet u Boru, Bor, Srbija
Izvod
Različite metalne vrste imaju široku primenu u stomatologiji, kako u cilju lečenja tako i iz estetskih razloga. Njihovim unošenjem u usnoj duplji dolazi do niza hemijskih i elektrohemijskih reakcija, što dovodi do rastvaranja metala i formiranja hemijskih jedinjenja. Oralna sredina predstavlja agresivni medijum za metale, dovodeći do njihove korozije. U ovom radu sumirani su dosadašnji rezultati o elektrohemijskom ponašanju bakra i legura bakra u sintetisanim rastvorima pljuvačke.
Ključne reči: bakar, dentalni materijali, korozija.
THE ELECTROCHEMICAL BEHAVIOR OF COPPER AND COPPER
ALLOYS AS BIOMATERIALS
ABSTRACT
Different types of metals are used in the stomatology for dental applications. The oral environment is aggressive medium for metals and leads to corrosion. The metals undergo to chemical or electrochemical reactions in the oral environment which resulting in dissolution and formation of different chemical compounds.
The present article reviews and discussed the electrochemical behavior of copper and copper alloys in synthetic saliva.
Keywords: copper, dental alloys, corrosion.
Membrane technology application in the
framework of zero emission concept
VUK RAJOVIĆ, JELENA MARKOVIĆ,
ALEKSANDAR JOKIĆ, JELENA ILIĆ
University of Novi Sad, Faculty of Technology, Novi Sad, Serbia
Abstract
The Zero emissions concept envisages all industrial inputs being used in final products or converted into value-added inputs for other industries or processes. In this way, industries are reorganized into clusters such that each industry’s wastes / by-products are fully matched with the input requirements of another industry, and the integrated whole produces no waste of any kind. This technique is based on the well-established economic analysis tool known as the input/output approach. In the framework of the zero emission concept capture of CO2 plays an important role. CO2 can be captured and permanently stored, or it can be re-used.
Carbon sequestration is a two-step process where the capture of CO2 from a gas stream is followed by its permanent storage. The capture step contributes 75% to the overall carbon sequestration process cost. For this reason, the scientific community has paid a great attention to the development of new processes for CO2 capture. Currently, there is a wide range of technologies to separate CO2 from gas streams. They are based on different physical and chemical processes including absorption, adsorption, cryogenics and membrane technology. The choice of a suitable technology depends on the characteristics of the flue gas stream and, as a consequence, on the power plant technology. As an alternative to conventional processes for CO2 separation and capture, membrane technology shows great potentiality for CO2 capture owing to its easy applicability, efficiency, flexibility, ability to maintain high CO2 pressure and to perform separations at low energy penalties. CO2-selective membranes allow separation of CO2 from different gas streams, such as: flue gas (post-combustion system), natural gas (natural gas processing) and hydrogen (pre-combustion systems) or oxygen from nitrogen (in an oxyfuel combustion system).
In the framework of zero emission concept, this paper gives an overview and analysis of the types of membranes used and membrane technology application in CO2 capture from the point of cost and energy consumption.
Keywords: zero emission, membrane technology, CO2 capture
PRIMENA MEMBRANSKE TEHNOLOGIJE U OKVIRU
POJMA NULTE EMISIJE
IZVOD
Koncept nulte emisije predviđa sve industrijske inpute koji se koriste u finalnoj proizvodnji ili pretvorene u inpute koji ulaze u dodatnu vrednost za druge industrije ili procese. Na ovaj način, industrije se reorganizuju u klastere tako da se otpad svake industrije, sporedni proizvod, u potpunosti poklapa sa ulaznim zahtevima drugih industrije, a integrisana celina ne proizvodi otpad bilo koje vrste. Ova tehnika se zasniva na dobro utvrđenim ekonomskim analizama alata poznatim kao ulazno / izlazni pristupi . U okviru koncepta nulte emisije hvatanje CO2 igra važnu ulogu. CO2 se može uhvatiti i trajno čuvati, ili se može ponovo koristiti.
Sekvestracija ugljenika je proces u dva koraka, gde je hvatanje CO2 iz gasne struje praćeno njegovim stalnim skladištenjem. Proces prikupljanja doprinosi 75% na ukupne troškove proces zaplena ugljena. Iz tog razloga, naučna zajednica je posvetila veliku pažnju razvoju novih procesa za prikupljanje CO2. Trenutno, postoji širok spektar tehnologija za separaciju CO2 iz gasnih struja. Oni su zasnovani na različitim fizičkim i hemijskim procesima, uključujući apsorpcije, adsorpciji i membranske tehnologije. Izbor odgovarajuće tehnologije zavisi od karakteristika protoka dimnih gasova i, kao posledica toga, na tehnologiji elektrane. Kao alternativa konvencionalnim procesima za separaciju i hvatanje CO2, membranska tehnologija pokazuje veliki potencijal za CO2 zbog njegove lakoća postavljanja, efikasnost, fleksibilnost, mogućnost održavanja visokog pritiska CO2 i obavljanja razdvajanja na niskim vrednostima energije. CO2– selektivna membrana dozvoljava odvajanje CO2 iz različitih gasnih struja, kao što su: dimnih gasova ( sistem posle sagorevanja ), prirodni gas ( prerada prirodnog gasa ) i vodonika ( sistemi pre sagorevanja ) ili kiseonika od azota ( u sistemu ’’oksifuel’’ sagorevanje).
U okviru koncepta nulte emisije, ovaj rad daje pregled i analizu vrsta membrana koje se koriste i primenjenih membranskih tehnologija za prihvatanje CO2 sa stanovišta troškova i energetske potrošnje.
Ključne reči: nulta emisija, membranska tehnologija, prihvatanje CO2
Influence of NaCl concentration on pitting corrosion
of extruded Al –Mg-Si alloy AA6060
JADRANKA MALINA1, JAGODA RADOŠEVIĆ2
1University of Zagreb, Faculty of Metalurgy, Sisak, Croatia
2University of Split, Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, Split, Croatia
Abstract
Extruded Al–Mg–Si alloys (AA6xxx series alloys) are the most common aluminum alloys for structural application due to reliable mechanical characteristics and corrosion properties. Spontaneously formed adherent aluminum oxide film on the surface protects Al and Al-alloys from corrosive attack in neutral media, but in chloride containing solutions, such thin and compact passive film is prone to breakdown.
In this study the corrosion behavior of commercial extruded Al-Mg-Si alloy AA6060 was investigated in NaCl solutions of different concentrations using anodic potentiodynamic polarization measurements under deaerated conditions at room temperature. It was shown that sensitivity to chloride attack increase with increasing Cl– concentration and depends on cathodic microconstituents in extruded Al–Mg–Si alloy.
Keywords: pitting corrosion, commercial Al-Mg-Si alloy, deaerated NaCl
Utjecaj koncentracije NaCl na piting koroziju ekstrudirane
Al –Mg-Si legure AA6060
Izvod
Ekstrudirane Al–Mg–Si legure (serija AA6xxx) najčešće se koriste u konstrukcijske svrhe zahvaljujući prihvatljivim mehaničkim i korozijskim svojstvima. Spontano formirani sloj aluminijeva oksida na površini Al i Al-legura štiti od korozijskih oštećenja u neutralnim medijima, ali u otopinama koje sadrže kloride dolazi do proboja takvog tankog i kompaktnog pasivnog filma. Kao posljedica tog procesa, nastaju na površini lokalna oštećenja i dolazi do pojave jamičaste korozije- pitinga.
U ovom je radu proučavano korozijsko ponašanje komercijalne ekstrudirane Al-Mg-Si legure AA6060 u otopinama NaCl različite koncentracije, metodom anodne potenciodinamičke polarizacije u deaeriranim uvjetima pri sobnoj temperaturi. Pokazalo se da sklonost lokalnoj koroziji raste s koncentracijom kloridnih iona i ovisi o katodnim mikrokonstituentima u ekstrudiranoj Al-Mg-Si leguri.
Ključne riječi: piting korozija, komercijalna Al-Mg-Si legura, deaerirana NaCl.
Teški metali u otpadnim vodama Rudnika bakra Majdanpek
SNEŽANA ŠERBULA1, ANA RISTIĆ1,
SREĆKO MANASIJEVIĆ2, NATALIJA DOLIĆ3
1Univerzitet u Beogradu, Tehnicki fakultet u Boru, Bor, Srbija
2Lola Institut, Beograd, Srbija
3Univerzitet u Zagrebu, Metalurski fakultet, Sisak, Hrvatska
Izvod
U radu su prikazane prosečne godišnje koncetracije jona teških metala u otpadnim vodama pogona Filtracije, Rudnika bakra Majdanpek. Na osnovu hemijskih analiza uzoraka otpadne vode utvrđen povišen sadržaj jona teških metala (Cu, Fe, Mn, Zn, Pb, Cd, i dr.) koji premašuju vrednosti maksimalne dozvoljone koncentracije definisane pravilnikom Republike Srbije. Dobijeni rezultati su upoređivani sa dozvoljenim graničnim vrednostima koncentracija koje propisuju Pravilnik Svetske zdravstevene organizacije i Direktiva 98/83/EC Evropske unije kao i sa nekim literaturnim podacima. Na kraju rada dat je predlog za smanjenje koncentracije jona teških metala u otpadnim vodama pogona filtracije primenom jonoizmenjivačke smole.
Ključne reči: otpadne vode, Rudnik bakra Majdanpek, Veliki Pek, joni teških metala
Heavy Metal Ions in the Wastewater of the Majdanpek Copper Mine
Abstract
The paper presents the average annual concentrations of heavy metal ions in the wastewater of the Majdanpek Copper Mine filtration plant. Chemical analyses of wastewater samples found an increased content of heavy metal ions (Cu, Fe, Mn, Zn, Pb, Cd etc.) that exceed the values of the maximum permissible concentration defined by the relevant Regulation of the Republic of Serbia. The obtained results were compared with the permissible concentration limits prescribed by the Regulation of the World Health Organization and Directive 98/83/EC of the European Union as well as with some data from the literature. The final section of the paper provides a suggestion for reducing the concentrations of heavy metal ions in the wastewater of the filtration plant by using ion exchange resin.
Keywords: wastewater, Majdanpek Copper Mine, Veliki Pek, heavy metal ions.
Valorizacija olova iz međuprodukata rafinacije bizmuta postupkom metalotermijske redukcije
VLADISLAV MATKOVIĆ, BRANISLAV MARKOVIĆ,
MIROSLAV SOKIĆ, VASO MANOJLOVIĆ
Institut za tehnologiju nuklearnih i drugih mineralnih sirovina, Beograd, Srbija
Izvod
U procesu rafinacije bizmuta, hlorovanjem legure Bi-Pb (bizmut pena) Kroll-Bettertonovim procesom kao međuprodukt pojavljuje se olovo-hlorid. Predmet ovog rada je valorizacija olova iz pomenutog međuprodukta postupcima aluminotermije i cinkotermije. Pored olova pomenutim postupcima dobijaju se glinica tehničkog kvaliteta (aluminotermija) i cinkhlorid (cinkotermija). Za ispitivanja su korišćeni sekundarni aluminijum i cink različite krupnoće. Ispitan je uticaj temperature, vremena, krupnoće reducenta i brzine mešanja (cinkotermija) na stepen iskorišćenja olova i definisani optimalni parametri procesa. Stepen iskorišćenja sirovog olova (98%Pb) iznosi 95-98% u slučaju aluminotermije i 85-90% u slučaju cinkotermije. Dobijeno sirovo olovo prerađuje se u rafinerijama olova. Glinica tehničkog kvaliteta ima primenu u keramičkoj industriji dok se cink-hlorid hidrometalurški tretira u cilju dobijanja 50%-nog rastvora cink-hlorida.
Ključne reči: olovo-hlorid, aluminotermija, cinkotermija, glinica, cink-hlorid, olovo
Recovery of Lead from By-products of the Bismuth Refining by metallothermic reduction treatments
Abstract
In the refinement process of bismuth by chlorinating of Bi-Pb alloy (Kroll-Betterton process) as a by-product lead chloride is formed. This study was focused on the lead valorization from PbCl2 by aluminothermic and zincothermic reduction. Besides lead, as a main product, during aforementioned process technical grade alumina (aluminothermic reduction) and ZnCl2 (zincothermic reduction) were also obtained. The secondary aluminium and zinc of different granulometry were used as a reducent. The effect of temperature, time, granulometry of reducents and stirring speed (zincothermic reduction) on the lead recovery was investigated. Based on the experimental results, the optimal process parameters were defined. Recovery of crude lead (containing 98%Pb) was in the range 95-98% for aluminothermic reduction and 85-90% for zincothermic reduction. The crude lead can be further processed in lead smelters. Technical grade alumina was used in ceramic industry, wile zinc-chloride is suitable for hydrometallurgical treatment giving 50 % solution of zinc-chloride as the final product.
Key words: lead chloride, aluminothermic reduction, zincothermic reduction, alumina, zinc-chloride, lead
Istraživanje dejstva korozije na dinamičku
čvrstoću kod nekih konstrukcionih čelika
BRANKO PEJOVIĆ, VLADAN MIĆIĆ, MILORAD TOMIĆ
Univerzitet u Istocnom Sarajevu, Tehnoloski fakultet Zvornik, Republika Srpska
Izvod
Dejstvom korozije spoljna površina metala postaje hrapava tako da dolazi do smanjenja čvrstoće kao posledica dejstva zareza. Ovome treba dodati da nastavljeno dejstvo korozije izgriza duboke i oštre zareze u metalu od čega nastaju sitne pukotine koje omogućuju još dalje prodiranje korozije. Zbog ovoga dinamička čvrstoća uz istovremeno dejstvo korozije jako opada tako da može dovesti do zamornog loma, što je pokazano u radu . Isto tako nije moguće uspostavljanje bilo kakve kvalitativne ili kvantitativne zakonitosti između dinamičke čvrstoće, dejstva korozije uostalom što važi i za dejstvo korozije i kod neopterećenog metalnog elementa. Ovo se mora u svakom pojedinom slučaju ispitati.
Ključne reči: zamaranje materijala, dinamička čvrstoća, dejstvo korozije, promenljivo opterećenje, konstrukcioni čelici
Investigation of corrosion effect on the dynamic strength
of some structural steels
Abstract
By corrosion effect, the surface of the metal becomes so rough that there are reduction in metal strength as a consequence of nicking. It should be added that the continuing effects of corrosion produces deep and sharp notches in the metal. It causes tiny cracks that allow further penetration of corrosion. As results of this activities, the dynamic hardness by simultaneously highly corrosion effect substantially decreases so that it may lead to fatigue failure, as shown in this paper. It is also not possible to establish any qualitative or quantitative legality between dynamic strength and corrosion effects. This hold for the effect of corrosion on unloaded metal element. This must be tested in all chance.
Keywords: Fatigue of materials, dynamic strength, corrosion effects, variable load, structural steels.
Uticaj neorganskih inhibitora na koroziono ponašanje Al-Si legura u vodenim rastvorima hlorida
JELENA PJEŠČIĆ, VESELINKA GRUDIĆ, DARKO VUKSANOVIĆ,
DRAGAN RADONJIĆ, REFIK ZEJNILOVIĆ
Univerzitet Crne Gore, Metalursko-tehnicki fakultet, Podgorica, Crna Gora
Izvod
Aluminijum, kao metal koji se može legirati sa velikim brojem elemenata, je veoma interesantan sa aspekta njegove primjene, odnosno on u određenim uslovima treba, osim mehaničkih, da zadovolji i korozione karakteristike. Sa ovog aspekta interesantne su legure aluminijuma na bazi sistema Al-Si, na čije ponašanje utiče hemijski sastav koji omogućava, pod određenim uslovima dobijanja, da se dobiju legure određene strukture koja zavisi od prisustva i koncentracije ostalih legirajućih elemenata. Na osnovu ovoga, pretpostavljeno je da se dobijene legure sistema Al-Si mogu koroziono „popraviti“ dodatkom inhibitora, koji će dati određenu efikasnost zaštite u 0,5M rastvoru HCl, odnosno da će se koroziona stabilnost ovih legura korišćenjem inhibitora Na2CO3, NaNO2 i Na2HPO4 dovesti na viši nivo.
Ključne riječi: inhibitori korozije, korozija metala, gustina struje, vodeni rastvori.
The influence of inorganic inhibitors on the corrosion behavior of Al-Si alloys in aqueous chloride solutions
Abstract
Aluminum, as a metal which can alloy with the large number of elements, is very interesting from the point of its application, i.e. it should, in certain circumstances, in addition to mechanical, satisfy the corrosion characteristics. From this point of interest, the alloys based on Al-Si systems, whose behavior affects the chemical composition, allow, under certain conditions, the obtain ing of certain alloy structure that depends on the presence and concentration of other alloying elements. On this basis, it was assumed that the resulting alloy system Al-Si corrosion can “fix” the addition of inhibitors, which will give some protection efficiency in 0.5M HCl solution, i.e. the corrosion stability of these alloys using inhibitors of Na2CO3 and Na2HPO4 NaNO2, bring to a higher level.
Keywords: corrosion inhibitors, corrosion of metals, current density, aqueous solutions.
Uticaj hrapavosti Zn-Mn prevlaka na korozionu postojanost
MILORAD V. TOMIĆ1, MARIJA G. RIĐOŠIĆ1,
MIOMIR G. PAVLOVIĆ1, MIROSLAV JOKIĆ1, JELENA BAJAT2
1Univerzitet u Istocnom Sarajevu, Tehnoloski fakultet Zvornik, Republika Srpska
2Univerzitet u Beogradu, Tehnolosko-metalurski fakultet, Beograd, Srbija
Izvod
U ovom radu je vršeno elektrohemijsko taloženje Zn-Mn prevlaka iz četiri rastvora, merena je njihova hrapavost i koroziona postojanost. Korišćene su katode od čelika nepoznatog sastava koje su podvgnute hemijskoj pripremi pre taložena dvojnih prevlaka Zn-Mn elektrohemijskim putem, a korišćene su anode od cinka čistoće 99,99%.Dvojne Zn-Mn prevlake su elektrohemijski taložene 15 minuta iz svih rastvora pri gustinama struje 1А/dm2, 2А/dm2 i 4 А/dm2. Svi eksperimenti su izvođeni galvanostatski (pri konstantnoj struji) u elektrohemijskoj ćeliji zapremine 500 cm3 i na sobnoj temperaturi.
Hrapavost elektrohemijski taloženih prevlaka Zn-Mn merena je uređajem TR200, a koroziona postojanost taloženih prevlaka određivanjem spektroskopije elektrohemijske impedance (SEI). Rezultati pokazuju da najmanju hrapavost imaju prevlake taložene pri gustini struje2 A/dm2 iz svih rastvovora. Izuzetak je rastvor 3sa odnosom [Mn2+]:[Zn2+]=1:2 kod koga je hrapavost najmanja u odnosu na sve rastvore i kreće se od 0,71 – 0,875 μm , anajmanja je pri gustini struje 4 А/dm2 i iznosi 0,71 μm. Na osnovu elektrohemijskih merenja utvrđeno je da je koroziono najpostojanija prevlaka Zn-Mn taložena pri gustini struje od 2 A/dm2 iz svih rastvora i pri gustini struje 4 А/dm2iz rastvora 3 sa odnosom [Mn2+]:[Zn2+]=1:2. To govori da je koroziona postojanost u direktnoj vezi sa hrapavošću i kompaktnosti Zn-Mn prevlake. Koroziono su najpostojanije prevlake sa najmanjom hrapavošću.
Ključne reči: brzina korozije, elektrohemijsko taloženje, gustina struje, hrapavost, spektroskopija elektrohemijske impedanse
IMPACT OF ROUGHNESS OF Zn-Mn COATINGS ON CORROSIVE STABILITY
Abstract
This paper involves electrochemical deposition of Zn-Mn coatings from four solutions. We measured their roughness and corrosion stability. We used cathodes made of steel of unknown composition that were licensed under the chemical preparation before the electrochemical deposition of dual-Zn-Mn coatings, and we also used the anode of zinc, purity of 99.99%. Dual Zn-Mn coatings were electrodeposited for 15 minutes from all of the solutions at a current densities of 1 A/dm2, 2 A/dm2 and 4 A/dm2. All experiments were carried out galvanostatialy (at constant current) in an electrochemical cell, volume of 500 cm3 and at room temperature.
The roughness of electrochemically deposited Zn-Mn coatings was measured by a TR200 device and corrosion stability of deposited coatings by determining the Electrochemical Impedance Spectroscopy (EIS). The results show that the coatings with the smallest roughness are coatings deposited at a current density of 2 A/dm2 from all of the solutions. The exception is solution 3 with the relation [Mn2+]:[Zn2+]=1:2 where the roughness is at the lowest level in comparison to all solutions, ranging from 0.71 to 0.875 μm, and the roughness is lowest at the current density of 4 A/dm2 and is 0.71 μm. Based on electrochemical measurements, the corrosive most stable Zn-Mn coating is deposited at a current density of 2 A/dm2 from all the solutions and at the current density of 4 A/dm2 from solution 3 with a ratio of [Mn2+]:[Zn2+]=1:2. This suggests that the corrosion stability is related directly to the roughness and compactness of Zn-Mn coatings. When it comes to corrosion, the most stable coatings are those with the lowest roughness.
Keywords: corrosion rate, electrodeposition, current density, roughness, electrochemical impedance spectroscopy.
Satirn as pesticide inhibitor for the corrosion of the galvanized iron in wastewater and its biological effect on Escherichia coli
Add El-Aziy S. FOUDA1, AYMAN Y. El-KHATEEB2,
MOHAMED FAKIH3, ALY M. El-AZALY4
1El-Mansoura University,Department of Chemistry, Faculty of Science,El-Mansoura; 2El-Mansoura University, Department of Agric. Chemistry,
Faculty of Agriculture, El-Mansoura; 3Lab manager in Talkha sanitation
plant, water and waste water company, Dakahlia; 4Nile Higher Institute for Engineering and Technology, El-Mansoura, Egyp
Abstract
Satirn is a type of the pesticides has been evaluated as green inhibitor for the corrosion of the galvanized iron in saline solution which was investigated by chemical and electrochemical measurements. The results of polarization showed that satirn acts as mixed type inhibitor. Inhibition was found to increase with the increase of satirn concentration reaching to approximately 90% at 250 ppm. The inhibitive action was discussed by the adsorption of a stable complex on the metal surface. The adsorption of satirn on the metal surface obeys Temkin adsorption isotherm. Satirn has a slightly effect on Escherichia Coli and can be applied safely in sanitation plants.
Keywords: corrosion inhibition, satirn, galvanized iron, saline solution.
Satirn kao pesticid inhibitor za koroziju pocinkovanog gvožđa u otpadnim vodama i njegov biološki efekat na Escherichia Coli
Izvod
Satirn je vrsta pesticida koji je ocenjen kao zeleni inhibitora za koroziju na pocinkovanom gvožđu u slanim rastvorima, što je istraživano hemijskim i elektrohemijskim merenjima. Rezultati polarizacije pokazali su da satirn deluje kao tip mešovitog inhibitora. Ispitivanjima je pronađeno da raste inhibitorno dejstvo sa povećanjem koncentracije satirna do približno 90% na 250 ppm.
Navedenim ispitivanjima je razmatrana adsorpcija stabilnih kompleksa na površini metala. Adsorpcija satirn na površini metala povinuje se Temkinovoj adsorpcijonoj izotermi. Satirn ima blagi uticati na Escherichia coli i može se bezbedno primeniti kod sanitarnih biljka.
Ključne reči: inhibitori korozije, Satirn, pocinkovano gvožđe , slani rastvor
Povećanje efikasnosti alata za kovanje Toyota difuzionim postupkom
ŽELJKO STOJANOVIĆ1, SPASOJE ERIĆ2
SANJA STANISAVLJEV3, MIĆA ĐURĐEV4
1Elemir, Elemir; 2Visoka tehnička škola strukovnih studija, Zrenjanin,
3Univerzitet u Novom Sadu, Tehnički fakultet „M. Pupin“, Zrenjanin, 4Univerzitet u Novom Sadu, Fakultet tehničkih nauka, Novi Sad, Srbija
Izvod
U radu je dat pregled literaturnih podataka o istraživanjima uticaja sloja vanadijum karbida deponovanog Toyota difuzionim postupkom na povećanje radnog veka i kvaliteta alata za obradu kovanjem. Kalupi za kovanje podvrgnuti su teškom adhezivnom i abrazivnom habanju, visokim naponima i temperaturama. Površina kalupa i region u blizini površine podvrgnuti su najtežim uslovima tokom obrade kovanjem i s toga većina defekata i uzroka destrukcije potiču iz ovog regiona. Zbog toga, rad uzima u razmatranje i različite komplikovane mehanizme habanja i destrukcije površine alata za obradu kovanjem, odnosno onu mrežu različitih aspekata koji utiču na vek trajanja alata a koji svojim delovanjem prouzrokuju prevremeno uklanjanje alata iz upotrebe.
Ključne reči: vanadijum karbid, kalup za kovanje, vek trajanja, habanje, destrukcija.
INCREASING THE EFFICIENCY OF FORGING TOOLS BY TOYOTA DIFFUSION PROCESS
Abstract
In this paper is given a review of literature data about research of influence layer of vanadium ca-rbide deposited by Toyota diffusion process on increasing of working life and quality of forging dies. Forging dies are subjected to severe adhesive and abrasive wear, high stresses and temperatures. The die surface and near surface region is subjected to the most severe conditions during forging and hence most defects and causes of failure of the dies originate from this region. Because of this, paper takes into consideration the different complicated mechanisms of wear and the destruction of the surface of tools for forging, apropos that network of various aspects which affect on the service life of the tool and by their actions causing premature removal tool from the use.
Keywords: vanadium carbide, mould forging, lifetime, wear, destruction.
The optimization of development process of petrol-gas stations network with the purpose to increase energy efficiency
LARISA JOVANOVIĆ1, DIJANA FEDJUNINA2,
MILAN RADOSAVLJEVIĆ3
1ALFA University, Belgrade,Serbia; 2Lukoil, Moscow, Russia; 3UNION – Nikola
Tesla University, Belgrade, Serbia
Abstract
Development of petrol/gas stations network requires a complex approach to the assessment of environmental impact. The use of appropriate indicators according DPSIR methodology enables optimization of processes at oil/gas stations and increase energy efficiency.
Use of renewable energy and new insulating materials has great importance to reduce energy consumption for heating of petrol/gas stations buildings. As a replacement styropor and styrodur (for added insulation of walls and floors) is much more efficient to use blocks of innovative insulating materials in the construction of new facilities.
Widespread application of renewable energy and thermal insulation materials in buildings of oil/gas stations, reducing electricity consumption by using energy-saving LED technology, as well as savings in transportation fuels reducing the weight of tankers using Al alloys and composite materials are the basic methods of increasing energy efficiency. The use of Al alloys in tankers and reservoirs design conductive to increase corrosion resistance.
Keywords: petrol/gas station, optimization, DPSIR methodology, indicators, energy efficiency, sustainable energy sources, LED technology, corrosion resistance, Al alloys.
Optimizacija razvojnih procesa na mrežama benzinskih pumpi u cilju povećanja energetske efikasnosti
Izvod
Razvoj mreže benzinskih pumpi zahteva kompleksan pristup proceni uticaja na životnu sredinu. Upotreba odgovarajućih indikatora prema DPSIR metodologiji omogućava optimizaciju procesa na benzinskim pumpama i povećanje energetske efikasnosti.
Korišćenje obnovljivih izvora energije i novih izolacionih materijala ima veliki značaj za smanjenje potrošnje energije za grejanje zgrada benzinskih stanica. Kao zamenu za stiropor i stirodur (za dodatnu izolaciju zidova i podova) i za izgradnju novih objekata mnogo je efikasnije koristiti blokove od inovativnih izolacionih materijala.
Široka primena obnovljivih izvora energije i termoizolacionih materijala u zgradama benzinskih stanica, smanjenje potrošnje električne energije korišćenjem LED tehnologija, kao i uštede goriva u transportu usled smanjene težine cisterni načinjenih od Al legura i kompozitnih materijala predstavljaju osnovne metode povećanja energetske efikasnosti. Upotreba Al legura u konstrukciji cisterni i rezervoara, takođe, povećava otpornost na koroziju.
Ključne reči: benzinska pumpa, optimizacija, DPSIR metodologija, indikatori, energetska efikasnost, obnovljivi izvori energije, LED tehnologija, otpornost na koroziju, Al legure.
Temperatura vazduha kao bitan klimatski – meteorološki parametar za određivanje evapotranspiracije
MILOŠ PETROVIĆ
Univerzitet u Nisu, Građevinsko – Arhitektonski fakultet, Nis, Srbija
Izvod
Temperatura vazduha spada u osnovne klimatske parametre. Kao klimatski parametar obezbeđuje energiju za isparavanje i premeštanje vodene pare sa površine koja isparava i određuje vrednost evapotranspiracije. Vazduh se zagreva posredstvom zemljine površine toplotom koja stiže sa Sunca. Veličina isparavanja u velikoj meri zavisi od temperature vazduha. Skoro sve metode zasnivaju svoje proračune na ovom klimatskom parametru, a neke metode samo na osnovu temperature vrše proračun evapotranspiracije.
Ključne reči: temperatura vazduha, klimatski parametar, evapotranspiracija
AIR TEMPERATURE AS AN IMPORTANT CLIMATE – METEOROLOGICAL PARAMETER FOR EVAPOTRANSPIRATION DETERMINATION
Abstract
The air temperature is one of the major climatic parameter. As climatic parameter, it provides energy for evaporation, transpiration and water vapor cycling that determine the value of evapotranspiration. The air is heated by the earth’s surface and by the solar radiation. Evaporation amount depend largely on the air temperature. Almost all methods for evapotranspiration estimation are based on climatic parameters, and only few methods use only temperature data.
Keywords: air temperature, climatic parameters, evapotranspiration.
