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Zaštita materijala 3. 2014

POSSIBILITIES FOR ECOLOGICAL PRODUCTION OF NEW WEAR RESISTANT Fe-C BASED ALLOYS

BOGOMIL VELIKOV KOLEV

Bulgarian Chemical Communications Instutute of Chemical Engineering,

Bulgarian Academy of Sciences, Sofia, Bulgaria

ABSTRACT
We present in general framework a part of by now obtained results of the authors studies in the period 1968-2003 about possibilities for obtaining new high-alloyed and wear-resistant founded alloys on Fe-C basis grey cast iron and complex alloyed steels and cast iron of different systems with different structure, reflected inover 130 publications, innovations, patents and other scientific studies. The results of the studies make possible to determine not only the directions for application of the obtained alloys in practices, but also to outline ecological and technical directions for obtaining of new high strength and wear-resistant alloys with N, using the possibilities of the new gas metallurgy with gaseous and volatile elements under pressure.
Keywords: new cast alloys, grey cast iron, complex alloyed steels and cast iron alloying with N, mechanic characteristics, ecology, application, perspectives, prognostication.

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MOGUĆNOSTI EKOLOŠKE PROIZVODNJE NOVIH Fe-C LEGURA
OTPORNIH NA HABANJE

IZVOD

U radu su predstavljeni rezultati ispitivanja u periodu od 1968-2003. godine o mogućnostima dobijanja visoko legiranih legura, otpornih na habanje, na bazi Fe-C sivog liva i čelika legiranog kompleksima i kovanog gvožđa različitih struktura, a koji su prikazani u raznim publikacijama, patentima i drugim naučnim studijama. Rezultati ispitivanja su utvrdili ne samo uslove za primenu dobijenih legura u praksi, nego su skicirali tehničke i ekološke smernice za postizanje visoke čvrstoće i otpornost na habanje legura sa N, koristeći nove tehnologije metalurgije gasa sa
gasovitim i isparljivim elementima pod pritiskom.
Ključne reči: nove livene legure, sivi liv, legirani čelici, liveno gvožđa legirano sa N, mehaničke karakteristike, ekologija, aplikacije, perspektive, predskazanje.

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 UTICAJ GRAFIČKIH BOJA NA RADNU I ŽIVOTNU SREDINU: PRIMENA EKOLOŠKIH BOJA

Nataša Tanjga, Nebojša Ćurčić, Darja Žarković

Visoka škola strukovnih studija,
Beogradska politehnika, Beograd, Srbija

IZVOD

U ovom radu su obuhvaćeni različiti materijali koji se koriste u proizvodnji grafičkih boja i analiziran je njihov uticaj na radnu i životnu sredinu, sa posebnim akcentom na upotrebu “eko boja”. Grafička boja predstavlja disperzni sistem sastavljen od većeg broja različitih komponenata (pigmenta, vezivnog sredstva, dodatnih materijala i nosećih supstanci) koje sve zajedno daju boji određena štamparska svojstva. Komponente boje u toku proizvodnje boja međusobno se dobro homogenizuju u pastu potrebne konzistencije. Grafička boja u svom sastavu ima različite vrste organskih i neorganskih materija koje svojim emitovanjem u vazduh, zemljište i vodu mogu trajno da naruše životnu sredinu, dok štetna isparenja iz boja narušavaju kvalitet radnog prostora i predstavljaju pretnju za zaposlene u pogonima štamparija. Najvažniji sastojak grafičke boje je pigment, koji daje obojenje. U sastavu pigmenta  najčešće su pojedini teški metali, dok su ulja koja ulaze u sastav boja dobijena destilacijom nafte i spadaju u opasne supstance koje mogu da deluju kancerogeno. Ekološki optimalan sastav grafičke boje nemoguće je odrediti, jer svaka tehnika štampe diktira deo moguće zamene određenih komponenti, zbog kvaliteta i brzine štampanja.
Ukoliko se uzme u obzir sastav boje, način dobijanja papira i pratećih repromaterijala u grafičkoj industriji, kao i to da tzv. “ekološke boje” ne mogu postići iste rezultate i kvalitet u štampi kao i konvencionalne boje  dolazi se do zaključka da je upravo razvijanje svesti i savesti samih štampara neophodna mera u procesu zaštite radne i životne sredine i očuvanju biodiverziteta. Na razvoj svesti i savesti rukovodstva i zaposlenih u štampariji najstimulativnije   deluje zakonska regulative, tako da je najveći zadatak na državi da donese i sprovede niz zakona koji će podstaknuti štamparije na korišćenje “ekoloških boja” i recikliranih materijala.

Ključne keči: grafička boja, ekologija, materijali, radna i životna sredina

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 THE INFLUENCE OF PRINTING INKS ON WORK CONDITIONS AND ENVIRONMENT: APPLICATION OF ECOLOGICAL COLOUR

ABSTRACT

This paper analyses the influence of content of printing inks (and different materials used in their production) on work surrounding and the environment, with the special review on eco inks usage. Printing ink presents dispersive system made of number of different components (pigments, vehicle, adhesive materials, aid materials etc.), which all brought together give specific properties suitable for the printing. During production, ink components are put under intensive homogenization and create a paste of specific consistency. Printing inks contain different kinds of organic and inorganic matter, which can be emitted to the air, soil and water, sometimes causing long-lasting damages to the environment. Beside that, toxic and dangerous vapors from inks violate quality of working surrounding and present the threat for employees in printing facilities. Pigment gives color in printing process and presents the most important constituent of the printing ink. Pigment usually contains different heavy metals, while some oils contained in inks, present distillation derivates of crude petroleum and are dangerous substances which might be cancerous. From the aspect of environmental protection, optimal content of printing ink is unavailable to determine, because each printing technique dictates its own demands in printing – quality and printing speed (connected with the properties of ink drying). Thus, the possibility of substitution dangerous substances in printing inks by less dangerous or harmless is limited.

Printing process is sensitive to the paper and ink properties, the way of paper production was done and the origin of other repro materials in printing industry. It is the fact that “eco inks” can’t achieve the same results and quality in printing as traditional inks. In that reason, some other measures can be also effective in protecting employees and the environment from the harmful effect of printing inks constituents. Uprising the consciousness of employees and the management of the printeries, conducting of preventive measures and measures for occupational safety present the main moto for socially and environmentally responsible printing business. The highest responsibility in preserving lives and the environment is on the state itself – to implement laws, to concern about their enforcement and to encourige and stimulate printeries to use recycled materials and eco inks.

Key words: printing inks, materials, safety at work, environment, eco-ink

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CORROSION BEHAVIOR OF  Cu-Ni-Ti IN ARTIFICIAL BLOOD PLASMA IN PRESENCE OF CHOLESTEROL

 S. John Mary1, S. Rajendran2

1Depatment of Chemistry, Loyola College, Chennai, India, 2Corrosion Research
centre, P.G. & Research Depatment of Chemistry,
G.T.N. Arts College, Dindigul, Tamilnadu, India

 

ABSTRACT

The Corrosion behaviour of Cu-Ni-Ti in artificial blood plasma in absence and presence of 50ppm and 100ppm of Cholesterol were studied by potentiodynamic polarization study and AC impedance spectra. The inhibition efficiencies of Cholesterol for the corrosion of Cu-Ni-Ti is increased with increasing concentration. Potentiodynamic polarization study shows that the corrosion of metal surface is greatly reduced with presence of Cholesterol. This may occur due to  the formation of protective layer formed on the metal in presence of Cholesterol. The polarization study leads to the corrosion inhibition of Cu-Ni-Ti in artificial blood plasma in absence and presence of 50 ppm of Cholesterol and100 ppm of cholesterol is in the following decreasing order:

 

Cu-Ni-Ti + artificial blood plasma +
100 ppm of Cholesterol

>

Cu-Ni-Ti + artificial blood plasma +
50 ppm of Cholesterol

>

Cu-Ni-Ti + artificial blood plasma

The AC impedance spectra study reveals that the corrosion inhibition of Cu-Ni-Ti in artificial blood plasma in absence and presence of 50 ppm of Cholesterol and100 ppm of Cholesterol is in the following decreasing order:

 

Cu-Ni-Ti + artificial blood plasma +
100 ppm of Cholesterol
> Cu-Ni-Ti + artificial blood plasma +
50 ppm of Cholesterol
> Cu-Ni-Ti + artificial blood plasma

Keywords: Corrosion, artificial blood plasma, Cu-Ni-Ti, Cholesterol

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 KOROZIONO PONAŠANJE LEGURE Cu-Ni-Ti U VEŠTAČKOJ KRVNOJ PLAZMI U PRISUSTVU HOLESTEROLA 

IZVOD

Koroziono ponašanje Cu-Ni-Ti u veštačkoj krvnoj plazmi u odsustvu i prisustvu 50ppm i 100ppm holesterola su proučavani potentiodinamičkom polarizacionom metodom i AC impedancom. Efikasnost inhibicije holesterola za koroziju Cu-Ni-Ti se povećava sa povećanjem koncentracije. Potentiodinamička polarizaciona metoda pokazuje da je korozija  površine metala u velikoj meri smanjena uz prisustvo holesterol. To se može desiti zbog formiranja zaštitnog sloja na metalu u prisustvu holesterola. Studija polarizacije dovodi do inhibicije korozije Cu-Ni-Ti u veštačkoj krvnoj plazmi u odsustvu i prisustvu 50 ppm i 100 ppm holesterola i nalazi se u sledećem opadajućem nizu:

 

Cu-Ni-Ti + veštačka krvna plazma +
100 ppm holesterola
Cu-Ni-Ti + veštačka krvna plazma +
50 ppm holesterola
Cu-Ni-Ti + veštačka krvna plzma

 

Studija AC  impedance otkriva da inhibicija korozije Cu-Ni-Ti u veštačkoj krvnoj plazmi u odsustvu i prisustvu 50 ppm i 100 ppm holesterola je u sledećem opadajućem nizu:

 

Cu-Ni-Ti + veštačka krvna plazma +
100 ppm holesterola
Cu-Ni-Ti + veštačka krvna plazma +
50 ppm holesterola
Cu-Ni-Ti + veštačka krvna plzma

Ključne reči: korozija, veštačka krvna plazma, Cu-Ni-Ti, holesterol

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 PROCESSING OF HIGH SULPHATE AND FREE LIME CALCAREOUS COAL FLY ASH FOR PRODUCING HIGH VOLUME BLENDED CEMENTS AND COMPLYING GRADE PRODUCTS EMPLOYED IN CIVIL ENGINEERING

 Arjan Korpa1, Bujar Seiti1, Kledi Xhaxhiu1, Altin Mele1, Reinhard Trettin2

1Department of Chemistry, Faculty of Natural Sciences,  Tirana, Albania, 

2University of Siegen, Institute for Building and Materials Chemistry,
  Siegen, Germany,

ABSTRACT

The present work outlines the results of a research attempt aimed at developing and evaluating the performance of processed fly ash. The raw fly ashes are very coarse, have variable chemical and mineralogical composition and contain higher than allowed amounts of sulphate and free lime. Furthermore these fly ashes contain enhanced levels of radionuclides (226Ra, 232Th, 40K), which originate from the parent coal mineral. The above listed properties prevent raw calcareous fly ashes to be employed as they are. Calcareous type lignite fly ash samples that were provided from various power plants were processed in ways which enable the highest possible and safe utilisation ratio of fly ash in cement and some civil engineering applications. The processing consisted mainly on blending and/or co-grinding whereby co-grinding was a combined grinding and hydrolisis in order to reduce the sulphate and free lime content of the blend. Provided an accurate and strict quality management system is available, calcareous fly ashes can easily and safely be employed at up to 50% ratio in blended cements that comply with the European standard requirement for cement. This processing way is an environmentally and economically sound alternative and probably one of the best strategies for the highest possible calcareous fly ash utilisation.

Key words: Calcareous type lignite fly ash,   high sulphate, high volume blended cements, complying grade products.

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OBRADA PEPELA OD KREČNJAČKOG UGLJA ZA PROIZVODNJU CEMENTA I POŠTOVANJE KVALITETA PROIZVODA KOJI SE KORISTE U GRAĐEVINARSTVU 

IZVOD

Ovaj rad prikazuje rezultate istraživanja u cilju razvijanja i vrednovanja rada prerađenog pepela. Sirovine “leteci pepeo“ su veoma grube, imaju promenljiv hemijski i mineraloški sastav i sadrže veće kolicine od dozvoljenih sulfata i slobodnog kreča.  Osim toga, leteći pepeo sadrži aktivne radionuklide (​​ 226Ra, 232Th, 40K), koji potiču iz  uglja. Krečnjački tipa lignita pepela uzorka, koji su obezbeđeni iz raznih elektrana, su obrađeni na način koji omogućavaju najviši mogući bezbedonosni odnos iskorišćenosti pepela u cementu i pojedinim građevinskim aplikacijama. Obrada se sastojala uglavnom u mešanju i / ili ko-brušenje, gde je ko-brušenja kombinovano brušenje i hidroliza kako bi se smanjili sulfati i  sadržaj kreča u mešavinama. Obezbeđivanje tačnog i strogog sistema upravljanja kvalitetom je dostupno i krečnjački leteći pepeo može se lako i bezbedno da koristi do 50% u pomešanom cementu, koji se u skladu sa evropskim standardom zahteva za cement. Ovakav način obrade je ekološki i ekonomski opravdan i verovatno jedan od najboljih strategija za moguće korišćenje krečnjački letećeg pepela.

Ključne reči:  Krečnjački tip lignita pepela, visok obim umešanosti cementa, sulfati, kvalitet proizvoda

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SEPARATION OF DISPESED OIL USING FIBER BED COALESCER

Radmila Šećerov Sokolović1, Dragan Govedarica1,
Dunja Sokolović2, Slobodan Sokolović2

1University of Novi Sad, Faculty of Technology, Novi Sad, 2University of Novi Sad,   Faculty of Engineering science, Novi Sad, Serbia

ABSTRACT

Although coalescers with fibers bed used in the industry for more than half a century, its design still requires experimental work. It is very hard to obtain some lasting relationships and interdependencies. Two-phase flow system (liquid / liquid dispersion) through the porous bed is quite complex and unknown. Fiber bed is a layer of high porosity, up to 98%, disordered structure; it is completely different from the bed of granular material that is still the focus of researchers modeling. Polymer fibers are elastic and their bed can compress provide different geometry. When you are looking to accomplish separation of different oil from waste water efficiency of different polymers can be extremely high for one oil, and low for another. This paper presents some results of the separation of different oils using fibers of different polymers. The experiments were performed in a laboratory device in the horizontal orientation of fluid flow, which in our studies proved the most effective. Model emulsion was prepared in drinking water at room temperature with 500 mg / l of dispersed mineral oil stirring constantly to obtain the average droplet size in the range of 10 μm.
Key words: oily water, bed coalescer, separation

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SEPARACIJA DISPERGOVANOG ULJA PRIMENOM KOALESCERA
SA VLAKNASTIM SLOJEM

IZVOD

Iako se koalesceri sa vlaknastim slojem koriste u industriji duže od pola veka njihovo projektovanje još uvek zahteva eksperimentalni rad. Kod njih je vrlo teško doći do nekih postojanih međuzavisnosti i relacija. Strujanje dvofaznog sistema (disperzija tečno/tečno) kroz porozni sloj je složeno i prilično neitsraženo.  Sloj vlakana je sloj visoke poroznosti, čak i do 98 %,  neuređene structure, on se u potpunosti razlikuje od sloja granulisanog materijala koji je još uvek u fokusu modelovanja istraživača. Polimerna vlakna su elastična i sloj je kompresibilan te je moguće njegovim sabijanjem obezbediti sloj različitih osobina. Kada se želi vršiti separacija kapi različitih ulja ispitivanjem efikasnosti različitih polimera može se konstatovati da je neki od njih izuzetno efikasan na jednom ulju, a krajnje neefikasan na drugom. U ovom radu biće prikazani neki rezultati separacije različitih ulja korišćenjem vlakana različitih polimera. Eksperimenti su realizovani na laboratorijskom uređaju pri horizontalnoj orijentaciji toka fluida, koja se u našim istraživanjima pokazala kao najefikasnija. Model emulzija je pripremana u vodi za piće sobne temperature dispergovanjem 500 mg/l mineralnih ulja uz permanentno mešanje tako da je prosečna veličina kapi u opsegu od 10 μm.

Ključne riječi: zauljena voda, koalescer, separacija

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UTICAJ TEMPERATURE NA OKSIDACIONU STABILNOST  INDUSTRIJSKIH ULJA

 Danka Šikuljak, Vesna Sarvan, Marija Milosavljević

Rafinerija ulja Modriča, Modriča, R.Srpska

IZVOD

U toku eksploatacije ulje postepeno mijenja svoje fizičke i hemijske karakteristike. Uzroci promjena u ulju su fizičko-hemijski i tribološki procesi u sistemu tokom rada, uslovi pod kojim ulje obavlja svoju funkciju i uslovi koji vladaju u okolini datog sistema.

Do degradacije ulja u toku eksploatacije dolazi uglavnom zbog oksidacije ugljovodonika pri visokim temperaturama. Temperatura je jedan od najvažnijih činilaca koji utiču na stepen oksidacije, bilo da se radi o industrijskim ili motornim uljima.

Produkti oksidacijske razgradnje ulja su peroksidi i drugi produkti oksidacije, kao što su alkoholi, ketoni, aldehidi, karboksilne kiseline. Nastali produkti međusobno reaguju i stvaraju visokomolekularne, u ulju netopive spojeve, dovodeći do promjena karakteristika ulja, čime se direktno utiče na funkcionalnost maziva.

U ovom radu je ispitan uticaj temperature na proces hemijske degradacije ulja. Ujedno je utvrđen i uticaj baznog ulja i inhibitora oksidacije na hemijsku stabilnost ulja.

Ključne riječi: oksidaciona stabilnost, temperatura, inhibitori oksidacije.

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INFULENCE OF TEMPERATURE ON THE OXIDATIVE STABILITY OF INDUSTRIAL OILS

ABSTRACT

During exploitation the oil gradually changes its physical and chemical properties. The causes of these changes in oil are physical-chemical and tribological processes in the system during operation, the conditions under which oil performs its function and the conditions in the system environment.

To the degradation of the oil during operation comes mainly due to the oxidation of hydrocarbons at high temperatures. Temperature is one of the most important factors that influence on the degree of oxidation, whether it is industrial or motor oil.

Oxidation products are peroxides as well as alcohols, ketones, aldehydes, carboxylic acids. These products react with each other and form a high molecular, insoluble compounds in the oil, what leads to changes of oil characteristics, with direct effect on the functionality of the lubricant.

In this paper is examined the effect of temperature on the process of chemical degradation of oil. Also is determined the influence of base oil and oxidation inhibitor on the chemical stability of the oil.

Key words: Oxidation stability, temperature, oxidation inhibitors.

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BIOCIDES IN METALWORKING FLUIDS

Marica-Maja Dugić1, Branka Dugić – Kojić1, Tatjana Botić2, Pero Dugić1

1Oil refinery Modrica, Modriča, 2University of Banja Luka, Faculty of Technology,
Banja Luka, R. Srpska


ABSTRACT

Metalworking fluids and coolants are used in various metalworking operations in many large factories, but also in small workshops. They are formulated not only to fulfill its basic functions, but also to be safe for environment and people that are exposed to its effect during work. One of the most common complications during use of MWF is its microbial degradation, because they are subject to impureness with bacteria and fungi, since they contain all nutritients needed for development and growth of microorganisms.

That’s why control and monitoring of microorganism’s growth are key factors in maintenance of MWF during use, and even during resting time, until its lifetime ends.

The addition of biocides contributes significantly to maintaining the quality of MWF, by protecting it from growth of potentially harmful microorganisms which could induce health problems with workers, but also affect the quality of processing and lifetime of MWF.

In this paper one can find results of analyses of emulsions that are treated with biocides of different chemical composition after microbial degradation, in very high and very low exploitation temperatures.

Key words: metalworking fluids and coolants, microbial degradation, biocides

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BIOCIDI U SREDSTVIMA ZA OBRADU METALA

IZVOD

Sredstva za hlađenje i podmazivanje (SHP) koriste se kod raznovrsnih operacija obrade metala u mnogobrojnim velikim fabrikama, ali i u malim radionicama. Formulisana su tako da pored ispunjavanja svoje osnovne funkcije budu bezbedna za okolinu i ljude koji su tokom rada izloženi njihovom uticaju. Jedan od najčešćih problema za vreme korišćenja SHP je njegova mikrobna degradacija, jer su ona podložna onečišćenju bakterijama i gljivicama, pošto  sadrže sve hranjive sastojke koji su potrebni za razvoj i rast mikroorganizama.

Zato su kontrola i praćenje porasta mikroorganizama bitni faktori kod održavanja SHP za vreme korišćenja, pa čak i tokom mirovanja, sve dok se ne završi životni vek sredstva.

Dodatak biocida može značajno doprinositi održavanju kvaliteta SHP, štiteći ga od porasta potencijalno štetnih mikroorganizama koji bi mogli uzrokovati zdravstvene probleme radnika, ali i uticati na kvalitet obrade i vreme radne funkcije sredstva.

U radu su navedeni rezultati analize emulzija koje su nakon mikrobne degradacije, u uslovima eksploatacije izložene izrazito visokim i niskim temperaturama, tretirane sa biocidima različitog hemijskog sastava.

Ključne riječi: Sredstva za hlađenje i podmazivanje, mikrobna degradacija, biocidi

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 ISPITIVANJE EFIKASNOSTI RAZLIČITIH SORPCIONIH MATERIJALA ZA UKLANJANJE  Cu(II)  JONA IZ VODENIH RASTVORA

Jelena Milojković1, Marija Mihajlović1, Tanja Šoštarić1, Zorica Lopičić1,
Marija Petrović1, Časlav Lačnjevac2, Mirjana Stojanović1

 1Institut za tehnologiju nuklearnih i drugih mineralnih sirovina ITNMS, Beograd, 2Univerzitet u Beogradu, Poljoprivredni fakultet, Beograd, Srbija

IZVOD

U ovom radu je ispitivana efikasnost (bio)sorpcije više materijala u uklanjanju bakarnih jona iz vodenog rastvora. Koncentracija bakarnih jona u rastvoru je bila 2mmol/l, M/V odnos 10 g/l, a pH rastvora je bio podešen na 5. Karakterizacija korišćenih materijala je izvršena uz pomoć skenirajuće elektronske mikroskopije. SEM-EDX analize materijala ukazuju na to da se vezivanje bakra dešava uglavnom preko jonske izmene.Uklanjnjanje jona bakra je ispitivano na sledećim materijalima: M.spicatum, koštica breskve, koštica kajsije, oklasak kukuruza, bentonit, zeolit, apatit, apatit i modifikovani NH4 zeolit i modifikovani NH4 zeolit. Najbolji rezultati dobijeni su sa bentonitom i biomasom M.spicatum. Stoga, bi trebalo ispitati mogućnost primene kombinovanih adsorbenata. Takođe, ovaj rad ima za cilj da promoviše biosorpciju i adsorpciju kao alternativne tehnologije za prečišćavanje otpadnih voda zasnovanih na upotrebi ekonomski prihvatljivih bioloških otpadnih materija i mineralnih sirovina  koje karakterišu niske cene i visoka efikasnost.

Ključne reči: sorpcija, otpadna biomasa, neorganski materijali, bakar, prečišćavanje vode

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INVESTIGATION OF EFFICIENCY OF DIFFERENT SORPTION MATERIALS FOR  Cu (II) REMOVAL FROM AQUOUS SOLUTIONS

ABSTRACT

In the present study the (bio)sorption efficiency of different materials for the removal of copper ions from aqueous solution has been investigated. Concentration of cooper ions in solutions was 2mmol/l, M/V ration 10 g/l and pH of the solutions were adjusted at 5. Used materials were characterized by scanning electron microscopy. SEM-EDX analyses of some materials indicate that copper binding occurs mainly through ion exchange mechanism, between Cu(II) and exchangeable cations. Removal of copper ions was investigated in the following materials: M.spicatum, peach pits, apricot pits, corn cobs, bentonite, zeolite, apatite, apatite and NH4 modified zeolite and modified zeolite NH4. Best results in copper ions removal showed bentonite and M.spicatum. Therefore, it should examine the possibility of using combined adsorbents. The work is aimed to promote biosorption and adsorption as alternative technologies for wastewater treatment based on the use of economically acceptable biological waste materials and mineral raw materials which are characterized by low cost and high efficiency.

Key words: sorption, waste biomass, inorganic materials, copper, water purification

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ASSESSMENT OF THE INTEGRITY OF WELDED PIPES

Živče Šarkoćević1, Miodrag Arsić2, Aleksandar Sedmak3, Bojan Međo4, Milan Mišić1

 1High Technical School of Professional Studies, Zvečan, 2Institute for
Testing of Materials (IMS), Belgrade, 3University of Belgrade, Faculty
of Mechanical Engineering, Belgrade, 4University of Belgrade, Faculty
of Technology and Metallurgy, Belgrade, Serbia

ABSTRACT

The subject of the paper is analysis of the integrity of welded pipes made of API J55 steel by high frequency contact welding (HF). Experimental research on the mechanical properties of the base material was conducted on pipes withdrawn from exploatation after 70 000 hours at service. Defect influence of the surface crack on the integrity of pipes was tested using hydrostatic pressure of pipes with axial surface crack in the base material. Fracture behaviour was tested using modified compact  specimen (CT), with the initial crack in the base material, welded joint and heat affected zone (HAZ). Critical value of the tensile strength factors KIc was determined based on the critical value  J of the integral JIc.

Apart from the experimental research, based on the derived values of Kr and S by applying fracture analysis diagram (FAD) an assessment of the integrity of welded pipes with axial surface crack on the outer surface area was conducted.

Keywords: seam casing pipes, axial surface crack, high frequency contact welding, fracture analysis diagram (FAD).

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PROCENA INTEGRITETA ZAVARENIH CEVI

 

IZVOD

Predmet rada je analiza integriteta zavarenih cevi izrađenih od čelika API J55 visokofrekventnim kontaktnim zavarivanjem (VF). Eksperimentalna ispitivanja mehaničkih osobina osnovnog materijala su izvršena na cevima povučenim iz ekspolatacije posle 70 000 sati rada. Uticaj oštećenja tipa površinske prsline na integritet cevi ispitan je hidrostatičkim pritiskom cevi sa aksijalnom površinskom prslinom u osnovnom materijalu. Ponašanje pri lomu je ispitivano korištenjem modifikovanih kompaktnih epruveta za zatezanje (CT), s početnom prslinom u osnovnom materijalu, zavarenom spoju i zoni uticaja toplote (ZUT). Kritična vrednost faktora intenziteta napona KIc određena je na osnovu kritične vrednosti J integrala JIc.

Osim eksperimentalnog istraživanja, na osnovu dobijenih vrednosti za Kr i Sr primenom dijagrama analize loma (FAD) izvršena je procena integriteta zavarenih cevi sa aksijalnom površinskom prslinom na spoljašnjoj površini.

Ključne reči:  aksijalna površinska prslina, visokofrekventno kontaktno zavarivanje, dijagram analize loma (FAD).

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OPTICAL MATERIAL PERFORMANCES, MEASUREMENT BY LASER IMPLEMENTATION AND INTERPRETATIONS

 Milesa Srećković1, Branka Kaluđerović2, Sanja Jevtić3, Zoran Latinović1,
Stanko Ostojić4, Đurđe Milanović5

1University of Belgrade, Faculty of Electrical Engineering, Belgrade
 2University of Belgrade,Vinca Institute,  Belgrade, Serbia, 3Arhi. pro,  Belgrade, 4University of Belgrade, Faculty of Technology and Metallurgy  Belgrade, 5Faculty of Computer sciences, Megatrend University, Belgrade, Serbia

 

ABSTRACT

Optical material performances along with main response functions belong to nondestructive measurements. Lasers brought new techniques beside accuracy increase. Nonlinear techniques introduced new solutions. These could be used in industry, biomedicine, and ecology with fast material  description  in  various  phases.  The  paper  is  elaborating  optical  characteristics  in various phases and descriptions (purity, dynamics and optical breakdowns). From the scattering point of view, water represented medium, unstable when pure comparing to organic etalons. As solvent for macromolecules and polymers it is difficult to be observed. In solutions with surface active materials, the stability of the formation is important. A few aspects of experiments and scattering theories (static and dynamic) of mono and polychromatic light including nonlinear approaches were analyzed.

Key words: laser, scattering, optical characteristics, diffusion, surface active material

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OPTIČKE OSOBINE MATERIJALA – MERENJA PRIMENOM
LASERA I INTERPRETACIJE

IZVOD

Optičke osobine materijala sa vezama sa glavnim funkcijama odziva pripadaju nedestruktivnim merenjima. Laseri su doneli nove tehnike, pored povećanja preciznosti. Nelinearne tehnike i nova rešenja se mogu koristiti i u industriji, biomedicini i ekologiji, sa brzim deskripcijama materijala u raznim fazama. Rad je posvećen optičkim karakteristikama materijala u raznim fazama i predstavama (čistoće, dinamike, optičkih proboja). Sa gledišta rasejanja, voda je predstavljala sredinu, kao čista nestabilnu u odnosu na organske etalone. Kao rastvarač za makromolekule i polimere, ona se “manje vidi”. Kod rastvora sa površinski aktivnim materijalima, važna je stabilnost  formacija.  Analizira  se  nekoliko  aspekata  teorija  i  eksperimenata  (statičkog  i dinamičkog) rasejanja mono i polihromatske svetlosti uz nelinearne prilaze.

Ključne reči: laser, rasejanje, optičke karakteristike, difuzija, površinski aktivan materijal.

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IZBOR POGODNOG NERĐAJUĆEG ČELIKA KAO KONSTRUKCIONOG MATERIJALA U HIDROMETALURGIJI CINKA

 Dušan Stanojević1, Leposava Filipović-Petrović2,
Mirjana Antonijević-Nikolić2, Milana Tomić2

 1Univerzitet u Istočnom Sarajevu,Tehnološki fakultet u Zvorniku,
 Zvornik, BiH, 2Visoka tehnološka škola strukovnih studija Šabac, Srbija

IZVOD

Pored široke primene u svakodnevnom životu, nerđajući čelici predstavljaju važne konstrukcione materijale u mnogim privrednim granama (hemijska, prehrambena i farmaceutska industrija, energetika, saobraćaj, rudarstvo, metalurgija i dr.). U hidrometalurgiji cinka, koja se bazira na sumporno-kiselim rastvorima složenog sastava koji pokazuju visoku korozionu agresivnost, veoma je teško pronaći adekvatne konstrukcione materijale. U tu svrhu koriste se različiti materijali, među kojim i neki nerđajući čelici, ali do sada postignuti rezultati, iz različitih razloga, uglavnom ne zadovoljavaju. U radu je ispitana primenljivost četiri savremena nerđajuća čelika (Uranus B6, Sanikro 25, 316L i 4573), u originalnim rastvorima iz proizvodnje elektrolitnog cinka na radnoj temperaturi od 950C, i poređeno je njihovo koroziono ponašanje. Na osnovu rezultata ispitivanja konstatovano je da bi ovi materijali bili ograničeno primenljivi u realnim uslovima u radnim rastvorima iz proizvodnje zbog nepotpunog pasiviranja  i moguće pojave piting korozije.

Ključne reči: Nerđajući čelici, hidrometalurgija cinka, koroziono ponašanje

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CHOICE suitable STAINLESS STEEL AS A CONSTRUCTION MATERIAL
FOR ZINC HYDROMETALLURGY

ABSTRACT

Beside vast usage in everyday life, stainless steels present important construction materials in many industrial fields (chemical, food producing and pharmaceutical industries, energetics, transport, mining, metallurgy, etc). In zinc hydrometallurgy, based on sulphur-acid solutions of complex composition which show high corrosion aggressiveness, it is very difficult to find suitable construction materials. For that purpose, different materials are used, among them are some stainless steels, but all achieved results, from these or those reasons, are mostly unsatisfactory. This paper examines the usage of four contemporary stainless steels (Uranus B6, Sanikro 25, 316L and 4573 ) in original solutions from electrolytic zinc production, at operating temperature of 950C , as well as their corrosion behaviour. Based on the examination results, it is established that these materials would be of limited usage in actual conditions, in operating solutions from production process due to incomplete passiveness and possible pitting corrosion.

Key words: Stainless steels, zinc hydrometallurgy, corrosion behaviour

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UTICAJ TEMPERATURE VODE I DOZE KOAGULANTA NA PROCES BISTRENJA  POVRŠINSKE VODE UZ MODELOVANJE PROCESA

Radovan Kukobat, Ljiljana Vukić, Dijana Drljača, Saša Papuga

Univerzitet u Banja Luci, Tehnološki fakultet, Banja Luka, R.Srpska, BIH


IZVOD

U  radu je metodom jar-testa ispitan uticaj temperature vode i doze koagulanta Al-sulfata na proces bistrenja vode rijeke Vrbas, sa ciljem dobijanja zahtjevanog kvaliteta sirove vode za određene namjene. Osnovna zapažanja tokom izvođenja testova koagulacije,  donesena su na osnovu indirektnog pokazatelja prisustva koloidnih čestica – turbiditeta (mutnoće) vode. Pored ovog, praćeni su i drugi relevantni parametri procesa – sadržaj prirodnih organskih materija (POM), pH-vrijednost, specifična provodljivost, sadržaj ukupnih organskih materija, kao i sadržaj aluminijuma. Na osnovu izmjerene mutnoće u optimalnim uzorcima,  kreiran je jednostavni matematički model, koji se može primijeniti za simulaciju procesa koagulacije/flokulacije, a sa ciljem optimalnog vođenja i moguće automatizacije procesa.

Ključne riječi: bistrenje površinske vode, koagulacija/flokulacija, aluminijumsulfat, mutnoća vode, matematički model.

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 WATER TEMPERATURE AND  FLOCCULANT CONCENTRATION  INFLUENCE ON THE SURFACE WATER CLARIFICATION  WITH PROCESS MODELING

ABSTRACT

Applying the jar-test method, the influence of water temperature and coagulant Al-sulphate dosage on a clarification process of water from river Vrbas have been analysed, in order to obtain the required quality of raw water for certain purposes. The main observations during conduction of coagulation tests, are based on  indirect indicators of the presence of colloidal particles – turbidity of water. Also,  the other relevant process parameters – the content of natural organic matter (POM), pH, specific conductivity, the total content of organic matter and aluminum content, have been determinated. Based on the measured turbidity in optimal samples, a simple mathematical model was developed. Developed model can be applied to simulate the process of coagulation/flocculation, with the goal of optimisation of control and possible automation of process.

Keywords: surface water clarification, coagulation/flocculation, aluminium sulphate, turbidity of water, mathematical model.

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STRATEGIJA BILJAKA U BORBI PROTIV FITOTOKSIČNIH KONCENTRACIJA METALA KAO KLJUČNI PREDUSLOV USPEŠNE FITOREMEDIJACIJE: ĆELIJSKI MEHANIZMI, deo I

 Slađana Č. Alagić

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

IZVOD

Tolerancija biljaka na stres izazvan metalima je jedan od ključnih preduslova uspešne fitoremedijacije. Brojne biohemijske reakcije odvijaju se u biljkama koje doživljavaju metalni stres, tako da one biljke koje imaju bolju sposobnost da se “podese” prema toksičnim efektima, biće i sposobnije da opstanu na oštećenim mestima, te samim tim predstavljaju i bolje kandidate za fitoremedijaciju. Pokazalo se pri tome, da biljke poseduju čitav niz mehanizama koji se mogu uključiti u  procese detoksifikacije i tolerancije prema metalnom stresu i to: vezivanje metala na
ćelijski zid i izlučivanje ekstracelularnih ekskudata korena, upotreba mikoriza u restrikciji kretanja metala prema korenu, redukovano usvajanje, ili čak aktivno  ispumpavanje metala iz citosola, popravka i zaštita plazma membrane, helatizacija metala u citosolu i kompartmentalizacija u vakuole.
Ključne reči: teški metali, biljke, tolerancija, fitoremedijacija

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PLANTS STRATEGIES AGAINST METAL PHYTOTOXICITY AS A KEY PREREQUISITE
FOR AN EFFECTIVE PHYTOREMEDIATION: CELLULAR MECHANISMS, part I

 

ABSTRACT

The tolerance of plants to metal stress is the key prerequisite for an effective phytoremediation. Numerous biochemical reactions occur in plants under metal stress, so those plants with better ability to adjust to the toxicity effects are able to survive in impacted sites and are better candidates for phytoremediation purposes. Plants pose a wide range of mechanisms which may be involved in metal detoxification/tolerance processes, such as: binding of metals to cell wall and
excretion of root exudates, restriction of metal movement to roots by mycorrhizas, reduced influx or even active efflux from the cytosol, reparation and protection of plazma membrane, chelation of metals in the cytosol and the compartmentation in the vacuole.
Keywords: heavy metals, plants, tolerance, phytoremediation

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MICROSTRUCTURAL PROPERTIES AND CAVITATION BEHAVIOR OF HYPEREUTECTIC  Al-Si ALLOY OBTAINED BY RHEOCATING PROCESS

Milena Ćosić1, Marina Dojčinović2, Zagorka Aćimović-Pavlović2

 1Tehnikum Taurunum College of Mechanical Engineering, Belgrade,
2University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia

 

ABSTRACT

The purpose of this study was to investigate possible application of AlSi alloy produced by rheocasting process in cavitation conditions. A rheocasting process was used to refine the as cast microstructure and improve the mechanical properties of Al18wt%Si alloy. Mechanical stirring was applied to the melt for different stirring time: 60,120,180s at different temperatures below the liquidus temperature of the alloy, using different stirring speed values, before pouring into a metallic mould. The microstructure of the cast samples was characterized by optical and scanning electron microscopy.

The paper investigates the effect of stirring speed and stirring time on the microstructure of AlSi alloy obtained by rheocasting procedure. The microstructure morphology and the alloy mechanical properties were found to depend on the stirring time and the stirring speed, and by using a suitable combination of these parameters it is possible to achieve high refinement efficiency by treating the melts in the semisolid state. Cavitation resistance of these samples has been tested. Mass loss of specimens was measured by an analytical method. The morphology of damaged surfaces of tested samples was examined using scanning electron microscopy (SEM). According to the results, it can be concluded that the samples of AlSi piston alloy prepared via rheocasting process, can be successfully applied in conditions where the cavitation resistance is needed.

Key words: Al-Si alloy, microstructure, rheocasting process, cavitation resistance

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MIKROSTRUKTURNA SVOJSTVA I KAVITACIONO PONAŠANJE NADEUTEKTIČKE   Al-Si LEGURE DOBIJENE REOKASTING POSTUPKOM

IZVOD

Cilj ovog istraživanja bio je da se ispita mogućnost primene AlSi legure dobijene reokasting postupkom u kavitacionim uslovima. Reokasting postupak je korišćen kako bi se poboljšala mikrostruktura  i mehanička svojstva Al18%Si legure. Primenjeno je mehaničko mešanje rastopa različitim brzinama mešanja, pri različitim vremenima mešanja od 60,120 i 180s, na različitim temperaturama ispod likvidus temperature pre livenja u metalni kalup.

Karakterizacija mikrostrukture livenih uzoraka izvedena je pomoću optičkog i skenirajućeg elektronskog mikroskopa.U radu je ispitivan uticaj brzine i vremena mešanja na mikrostrukturu legure, koja je dobijena pomenutim postupkom.Utvrđeno je da mikrostrukturna morfologija i mehanička svojstva zavise kako od brzine mešanja tako i od vremena mešanja, i da se podesnom kombinacijom ovih parametara mogu postići visoka rafinirajuća svojstva rastopa, koji je  procesiran u oblasti poluočvrslog stanja.

U radu je ispitivana kavitaciona otpornost uzoraka. Gubitak mase meren je primenom analitičke metode. Morfologija oštećenih površina uzoraka ispitivana je pomoću SEM-a. Prema rezultatima ispitivanja, može se zaključiti da uzorci AlSi klipnih legura dobijenih reokasting postupkom, mogu se uspešno primeniti u uslovima gde je potrebna kavitaciona otpornost.

Ključne reči: Al –Si legure, mikrostruktura, reokasting postupak, kavitaciona otpornost

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 pH VREDNOST I KONCENTRACIJA UKUPNOG SUVOG OSTATKA I SUSPENDOVANIH MATERIJA U OTPADNIM VODAMA RUDNIKA BAKRA MAJDANPEK

Snežana Šerbula1,  Ana Ristić1,  Srećko Manasijević2, Natalija Dolić3,

Novica Davitkov1

1Univerzitet u Beogradu, Tehnički fakultet u Boru, Bor, 2Lola institut, Beograd,
 3Univerzitet u Zagrebu, Metalurški fakultet, Sisak, Hrvatska 

 

IZVOD

U radu su analizirane prosečne godišnje vrednosti: koncentracije ukupnog suvog ostatka, pH vrednosti i suspendovanih materija u otpadnim vodama rudnika bakra Majdanpek. Pokazalo se da pojedini rezultati premašuju vrednosti maksimalne dozvoljone koncentracije definisane zakonskom regulativom 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 poznatim svetskim primerima. Predložena je dorada gravitacionog taložnika da bi se smanjio gubitak koncentrata bakra u obliku suspendovanih čestica u otpadnim vodama pogona filtracije primenom koagulanata.

Ključne reči: otpadne vode, suvi ostatak, suspendovane čestice, Rudnik bakra Majdanpek, Veliki Pek

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pH  VALUE AND CONCENTRATIONS OF TOTAL DRY RESIDUE AND SUSPENDED MATTER IN THE WASTERWATER OF THE MAJDANPEK COPPER MINE

ABSTRACT

The paper analyses the average annual values of the concentration of total dry residue, pH value and suspended matter in the wastewater of the Majdanpek Copper Mine. It has been shown that certain results exceed the values of the maximum permissible concentration defined by the relevant regulations 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 well-known examples in the world. The paper proposes an adjustment to the settling basin in order to reduce the loss of copper concentrate in the form of suspended particles in the wastewater of the filtration plant by using coagulants.

Keywords: wastewater, dry residue, suspended particles, Majdanpek Copper Mine, Veliki Pek

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MIKROMEHANIČKA ANALIZA LOMA LAMINATNOG STAKLO-EPOKSI KOMPOZITNOG MATERIJALA ISPITIVANOG SAVIJANJEM

 Miljana Krstić1, Dragoljub Ilić2, Dragoljub Bekrić3, Jelena Petrović1,
Ivica Vujičić1, Slaviša Putić1

1Univerzitet u Beogradu, Tehnološko-metalurški fakultet, Beograd,
2Vazduhoplovna akademija, Beograd, 3Univezitet u Beogradu, Mašinski fakultet, Beograd, Srbija

 

IZVOD

Predmet i cilj ovog rada predstavlja mikromehanička analiza lomova nastalih mehaničkim ispitivanjima laminatnog staklo-epoksi kompozitnog materijala na savijanje. Struktura staklo-epoksi kompozitnog materijala je stakleno platno 280 g/m², “twill tkanje”, širine 100 cm, tip – Interglas 92125 i epoksi smola tip MGS L-135. Uzorci su oblikovani ručnom metodom sa 35% zapreminskog udela vlakana. Prethodnim mehaničkim ispitivanjima su dobijeni relevantni podaci o zateznim i savojnim mehaničkim svojstvima. Analizom sa fotografija na prelomnim površinama većih uvećanja i sa skening elektronskog mikroskopa (SEM) biće izvedena mikromehanička analiza kojom će se doći do saznanja o mehanizmima oštećenja i razvoju prsline do konačnog loma pri delovanju savojnog opterećenja.

Ključne reči: mikromehanička analiza, staklo-epoksi kompozitni materijali, mehanika oštećenja kompozita, ispitivanje na savijanje staklo-epoksi kompozitnog materijala

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 Micromechanical fracture analysis of laminated GLASS-epoxy composite material tested bending

ABSTRACT

The object and purpose of this work is the micromechanical analysis of failures caused by mechanical tests of laminate glass-epoxy composite material in bending. The structure of glass-epoxy composite material is a glass fabric 280 g / m², “twill weave”, width 100 cm, type – Interglas 92125 and epoxy resin type MGS L-135. Samples are shaped manual method with 35% volume fraction of fibers. Previous mechanical tests were obtained relevant data on tensile and flexural mechanical properties. By analyzing the images of fracture surfaces of larger magnification with a scanning electron microscope (SEM) will be performed micromechanical analysis that will lead to the knowledge of the mechanisms of damage and crack growth to final fracture in action bending loads.

Key words: micromechanical analysis, glass-epoxy composite materials, damage mechanics of composites, testing for bending glass-epoxy composite material

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