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Zaštita Materijala 2. 2021

Mirjana Antonijević Nikolić1*, Jelena Đuričić Milanković1, Đorđe Nikolić2, Dušan Stanojević1

1Akademija strukovnih studija Šabac, Odsek za medicinske i poslovno-tehnološke studije,  Šabac, Srbija,  2HBIS GROUP Serbia Iron & Steel doo. Beograd, ogranak Šabac, Šabac, Srbija

Naučni rad
ISSN 0351-9465, E-ISSN 2466-2585
UDC:351.777.8:631.416.8:608.32:502/504
https://doi.org/: 10.5937/zasmat2102083A


Zastita Materijala 62 (2)
83 – 94  (2021)

 

The content of trace elements in the urban soil of Šabac and ecological risk assessment

Abstract

This study deals with the assessment of trace elements pollution of urban soil in Šabac. A total of 32 samples of the surface layer of soil (up to 10 cm deep) were collected from the locations of three city parks in the urban zone. Pseudototal concentrations of seven elements: copper (Cu), lead (Pb), cobalt (Co), nickel (Ni), manganese (Mn), cadmijum (Cd) and chrome (Cr) were determined in the samples after aqua regia digestion, using atomic absorption spectrophotometry. The abundance of elements in the analyzed soil samples was: Mn >> Pb> Cr> Ni> Cu> Co> Cd. The conducted correlation analysis showed good correlation of the pairs of Cu – Pb, Cu – Cd and Pb – Cd elements, while the cluster analysis singled out two main groups of elements. The first group included Pb, Cd, and Cu, indicating that these elements originated from anthropogenic sources, while the remaining elements were probably of geogenic origin. Based on the obtained results, the assessment of the level of soil contamination with trace elements was performed, as well as the assessment of the ecological risk. Mean values of contamination factors indicate that the soil from all three examined sites is contaminated with Pb and Cd. The Cd has the higher individual potential ecological risk then the other elements.

Keywords: urban soil, trace elements, pollution, Šabac

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Sadržaj elemenata u tragu u urbanom zemljištu Šapca i procena ekološkog rizika

Izvod

Ovaј rad se bavi procenom kontaminacije urbanog zemljišta u Šapcu elementima u tragu. Sa lokacija tri gradska parka u urbanoj zoni sakupljeno je ukupno 32 uzorka površinskog sloja zemljišta (do 10 cm dubine). Pseudototalne koncentracije sedam elemenata: bakra (Cu), olova (Pb), kobalta (Co), nikla (Ni), mangana (Mn), kadmijuma (Cd) i hroma (Cr) određene su u uzorcima posle digestije u smesi kiselina (HCl/HNO3), korišćenjem atomske apsorpcione spektrofotometrije. Zastupljenost elemenata u analiziranim uzorcima zemljišta je bila: Mn>> Pb > Cr > Ni > Cu > Co > Cd. Korelaciona analiza je pokazala dobru korelisanost parova elemenata Cu – Pb, Cu – Cd i Pb – Cd, dok su klasterskom analizom izdvojene dve glavne grupe elemenata. Prva grupa je uključivala Pb, Cd i Cu, što je ukazivalo da ovi elementi potiču iz antropogenih izvora, dok su preostali elementi verovatno geogenog porekla. Na osnovu dobijenih rezultata izvršena je procena nivoa kontaminacije zemljišta elementima u tragu, kao i procena ekološkog rizika. Srednje vrednosti faktora kontaminacije ukazuju da je zemljište sa sve tri ispitivane lokacije kontaminirano Pb i Cd. Od svih elemenata najveći potencijalni ekološki rizik ima Cd.

Ključne reči: urbano zemljište, elementi u tragu, zagađenje, Šabac

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Vujadin Aleksić1, Marina Dojčinović2, Ljubica Milović2, Bojana Zečević3*,  Ana Maksimović3

1Institut za ispitivanje materijala-IMS Institut, Beograd, Srbija,  2Univerzitet u Beogradu, Tehnološko metalurški fakultet, Beograd, Srbija,  3Inovacioni Centar, Tehnolosko metalurškog fakulteta, Beograd, Srbija

Naučni rad
ISSN 0351-9465, E-ISSN 2466-2585
UDC:669.15‑194.2‑044.956:539.388.1
https://doi.org/:10.5937/zasmat2102095A


Zastita Materijala 62 (2)
83 – 94  (2021)

 

Mechanisms and morphologies of cavitation demage of NN-70 steel

Abstract

Broken test tubes for low-cycle fatigue testing of Nionicral 70 (NN-70) parent material (PM) steel and simulated heat-affected zones (SHAZ) were used to produce samples for cavitation resistance testing. Ultrasonic vibrational cavitation method (stationary sample method) was applied for testing in laboratory conditions. The test conditions and procedure, sample preparation and interpretation of results are defined by ASTM G32. The surfaces of the NN-70 PM and SHAZ steel samples were exposed to cavitation and damage monitoring over time. Measuring the weight loss of samples on the analytical balance after a certain time allowed us to determine the cavitation velocity as a measure of the material’s resistance to the effect of cavitation. Scanning electron microscopy (SEM) was applied to monitor variations in surface morphology with changing test time. On the basis of the results of the cavitation resistance test, the morphologies of the surface damage for different exposure times of the cavitation of PM and SHAZ steel NN-70 samples were analyzed, as well as the mechanisms that led to the damage of the sample surfaces.

Keywords: cavitation; steel NN-70; PM; SHAZ; mechanisms and morphologies of damage

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Mehanizmi i morfologije kavitacionog oštećenja čelika Nionikral 70

Izvod

Polomljene epruvete za ispitivanje niskocikličnim zamorom čelika Nionikral 70 (NN-70) osnovnog materijala (OM) i simulirane zone pod uticajem toplote (SZUT) poslužile su nam za izradu uzoraka za ispitivanje otpornosti na kavitaciju. Za ispitivanje u laboratorijskim uslovima primenjena je ultrazvučna vibraciona metoda kavitacije (metoda stacionarnog uzorka). Uslovi i procedura ispitivanja, priprema uzoraka kao i interpretacija rezultata definisani su standardom ASTM G32. Površine uzoraka čelika NN-70 OM i SZUT bile su izložene dejstvu kavitacije i praćenju oštećenja kroz određeno vreme. Merenje gubitka mase uzoraka na analitičkoj vagi posle određenog vremena omogućilo nam je određivanje kavitacione brzine kao mere procene otpornosti materijala na dejstvo kavitacije. Za praćenje varijacija u morfologiji površine s promenom vremena ispitivanja primenjena je skenirajuća elektronska mikroskopija (SEM). Na osnovu rezultata ispitivanja otpornosti na kavitaciju u radu su analizirane morfologije oštećenja površina za različita vremena izlaganja dejstvu kavitacije uzoraka OM i SZUT čelika NN-70 kao i mehanizmi koji su doveli do oštećenja površina uzoraka.

Ključne reči: kavitacija; čelik NN-70; OM; SZUT; mehanizmi i morfologije oštećenja

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Mihailo Mrdak1*, Časlav Lačnjevac2, Marko Rakin3,Đorđe Janaćković1, Darko Veljić1


1University of Belgrade, Inovation Center – Faculty of Technology and Metallurgy, Belgrade, Serbia,2University of Belgrade, Faculty of Agriculture, Belgrade, Serbia,  3University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia

Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC:621.793.7‑034.14:544.344.016.5
https://doi.org/:10.5937/zasmat2102106M

Zastita Materijala 61 (2)
106 – 112  (2021)

 

Characterization of vacuum plasma spray VPS – W coating deposited on stainless steel substrates

Abstract

In this paper, studied was the melting of W powder particles in plasma, their behavior at oxidation as well as the mechanism of hardening on the surface of the substrate. Tungsten coating layers were deposited with vacuum plasma spray technology (VPS) on the test specimens of steel Č.4171 (X15Cr13 EN10027). VPS technology has advantages over the APS technology due to decreased oxidation of melted powder particles, by producing a coating with a controlled proportion of micro pores and greater uniformity of the deposited layers. Evaluation of mechanical characteristics of the layers was done by examining the microhardness using the HV0.3 method and tensile bond strength by tensile testing. The microstructures of the deposited layers were analyzed by means of optical microscopy (OM) and scanning electron microscopy (SEM). The results obtained showed that the tungsten coating consisted of well melted particles that interconnected and were overlapping, which shows a typical lamellar microstructure. Present in the microstructure are micro pores in very small proportion at the inter-lamellar boundaries. Tests have shown that layers of W coating deposited by plasma spray in inert gas shielding at low pressure have good mechanical properties and microstructure, which in the fully enables its use in exploitation.

Keywords: tungsten, vacuum plasma spray (VPS), microstructure, interface, microhardness, bond strength.

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Karakterizacija vakuum plazma sprej VPS- W prevlake deponovane na čeličnim podloga

Izvod

U ovom radu proučavano je topljenje čestica praha W u plazmi, njihovo ponašanje na oksidaciju kao i mehanizam očvršćavanja na površini substrata. Slojevi volfram prevlake su deponovani sa vakuum plazma sprej tehnologijom (VPS) na ispitnim uzorcima od čelika Č.4171 (X15Cr13 EN10027). VPS tehnologija ima prednosti u odnosu na APS tehnologiju zbog smanjene oksidacije istopljenih čestica praha, proizvodeći prevlaku sa kontrolisanim udelom mikro pora i većom uniformnosti deponovanih slojeva. Procena mehaničkih karakteristika slojeva je urađena ispitivanjem mikrotvrdoće metodom HV0.3 i zatezne čvrstoće spoja ispitivanjem na zatezanje. Analizirane su mikrostrukture deponovanih slojeva pomoću optičke mikroskopije (OM) i skening elektronske mikroskopije (SEM). Dobijeni rezultati su pokazali da se volfram prevlaka sastojala od dobro istopljenih čestica međusobno povezanih i preklopljenih, koja pokazuje tipičnu lamelarnu mikrostrukturu. U mikrostrukturi su prisutne mikro pore u veoma malom udelu koje se nalaze na među-lamelarnim granicama. Ispitivanja su pokazala da slojevi W prevlake deponovani plazma sprejom u zaštritnoj atmosferi inertnog gasa na niskom pritisku imaju dobre mehaničke osobine i mikrostrukturu, koje u potpunosti omogućavaju njenu primenu u eksploataciji.

Ključne reči: volfram, vakuum plazma sprej (VPS), mikrostruktura, interfejs, mikrotvrdoća, čvrstoća spoja

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Olga Myronova1*, Vyacheslav Goryany2

1Univerzitet u Duisburgu, Institut za tehnologije metala, Duisburg, Nemačka,  2Karl Buch Walzengiesserei GmbH & Co. KG, Düsseldorf,  Nemačka

Naučni rad
ISSN 0351-9465, E-ISSN 2466-2585
UDC: 620.172.24-034.14:66.094.5
https://doi.org/:10.5937/zasmat2102113M


Zastita Materijala 61 (2)
113 – 125  (2021)

 

Influence of non-metallic inclusions on the destruction of mechanically loaded steel products

Abstract

The paper describes in detail the reasons for the cracking of steel products, despite the fact that all the conditions of mechanical loading were met – the working stresses were much less than the maximum tensile stress of the applied type of steel. Deep metallographic analysis, as well as stress analysis show that the main cause is the formation of non-metallic inclusions in the material of the product, which essentially change its mechanical characteristic.

Keywords: non-metallic inclusions, steel rollers, mechanical fracture, thermal expansion
coefficient, metallographic tests

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Uticaj nemetalnih uključaka na razaranje mehanički opterećenih čeličnih proizvoda

Izvod

U radu su detaljno opisani razlozi pucanja čeličnih proizvoda i pored toga što su svi uslovi mehaničkog opterečenja ispoštovani – radna naprezanja bila su mnogo manja od maksimalnog naprezanja na zatezanje primenjene vrste čelika. Dubinska metalografska analiza, kao i analiza naprezanja pokazuju da se osnovni uzrok tome nalazi u nastajanju nemetalnih uključaka u samom materijalu proizvoda, koji suštinski menjaju njegove mehaničke karakteristike.

Ključne reči: nemetalni uključci, čelični valjci, mehanički lom, keficijent termičkog širenja, metalografska ispitivanja

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Ljubiša Andrić1*, Marko Pavlović2, Marina Dojčinović3, Dragan Radulović1

1Institut za tehnologiju nuklearnih i drugih mineralnih sirovina, Beograd, Srbija, 2Kontrol Inspekt- Beograd, Beograd, Srbija, 3Univerzitet u Beogradu, Tehnološko- metalurški fakultet, Beograd, Srbija

Naučni rad
ISSN 0351-9465, E-ISSN 2466-2585
UDC: 553.679-044.956:553.086
https://doi.org/:10.5937/zasmat2102126A


Zastita Materijala 62 (2)
126 – 134  (2021)

 
 

Determination of resistance to cavitation of pyrophyllite samples

Abstract

The resistance under the action of cavitation of sintered pyrophillite samples was investigated. The initial sample of pyrophillite from the Parsovic-BiH deposit was ground a vibrating mill to a granulation of 20 mμ, pressed and sintered at temperatures (⁰C): 100; 1100; 1200. To assess cavitation resistance, the change in sample mass as a function of cavitation time was monitored. The cavitation erosion test was performed using the ultrasonic vibratory cavitation test method according to the ASTM G-32 standard. Cavitation velocites were calculated for all samples, as a basic indicator of the resistance of the material under the action of cavitation. The change in the morphology of the surface with the test time was followed by scanning electron microscopy. Based on the values of cavitation velocity and analysis of the surface damage morphology, the cavitation resistance  of the tested samples based on pyrophillite was determined. The obtained results indicate that the samples of sintered pyrophillite have satisfactory resistance to the action of cavitation and be applied in conditions of lower cavitation loads.

Keywords: pyrophillite, cavitation resistance, mass loss, damge morphology, image analysis

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Određivanje otpornosti na dejstvo kavitacije uzoraka pirofilita

Izvod

U radu je ispitivana otpornost pod dejstvom kavitacije uzoraka sinterovanog pirofilita. Polazni uzorak pirofilita iz ležišta Parsović- BiH mleven je u vibracionom mlinu na granulaciju 20μm, presovan je i sinterovan na temperaturama (ºC): 1000; 1100; 1200. Za procenu kavitacione otpornosti praćena je promena mase uzorka u funkciji vremena delovanja kavitacije. Primenjena je ultrazvučna vibraciona metoda sa stacionarnim uzorkom prema standardu ASTM G32. Izračunate su kavitacione brzine za sve uzorke, kao osnovni pokazatelj otpornosti materijala pod dejstvom kavitacije. Promena morfologije površine uzorka sa vremenom ispitivanja praćena je primenom skenirajuće elektronske mikroskopije. Na osnovu vrednosti kavitacione brzine i analize morfologije oštećenja površine određena je kavitaciona otpornost ispitivanih uzoraka na bazi pirofilita. Dobijeni rezultati ukazuju da uzorci sinterovanog pirofilita imaju zadovoljavajuću otpornost na dejstvo kavitacije i mogu se primeniti u uslovima manjih kavitacionih opterećenja.

Ključne reči: pirofilit, kavitaciona otpornost, gubitak mase, morfologija oštećenja, analiza slike

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Vukoman Jokanović1,2*

1Institute of Nuclear Sciences Vinča, Belgrade, Serbia

2ALBOS Ltd, Innovative Company, Belgrade, Serbia

Review paper
ISSN 0351-9465, E-ISSN 2466-2585
UDC: 576.36:28-187.3
https://doi.org/10.5937/zasmat2102135J

Zastita Materijala 62 (2)
135 – 140  (2021)

 
 

The short story of the miraculous daily resurrection of life in us

Abstract

The development of modern science in various fields today often exceeds the limits and ideas of the bravest philosophers and scientists of our time. And certainly the most intriguing areas of research are those based on the molecular basis of life processes. The complexity and complexity of the human body, countless intertwined feedback loops that regulate internal processes in the body and enable its survival, can best be interpreted at the micro and nano level, ie at the level of the cell and its subcellular structures. This opens up huge potentials for understanding and influencing living systems, but also unlimited challenges for science. The monograph “How cells live and die in us” is unique in many ways. The multidisciplinary procedure provides a comprehensive overview of the complexity of the human body, as well as its possible functioning at the cellular micro and nano level, ie at the level of molecules, atoms, nuclei, protons, etc. The story is inspired by Balasevic’s line between the year of birth and the year of death.

Keywords: cell life, cell death, stem cells, brain, DNA, life eternity

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Priča o čudesnom svakodnevnom vaskrsenju života u nama

Izvod

Razvoj savremene nauke u različitim oblastima danas često prevazilazi granice i ideje najhrabrijih filozofa i naučnika našeg doba. A sigurno najintrigantnija područja istraživanja su ona koja su bazirana na molekulskim osnovama životnih procesa. Složenost i kompleksnost ljudskog tela, bezbroj isprepletanih povratnih sprega koje regulišu unutrašnje procese u organizmu i omogućavaju mu opstanak, najbolje se mogu tumačiti na mikro i nano nivou, odnosno na nivou ćelije i njenih subćelijskih struktura. Time se otvaraju ogromni potencijali za razumevanje i uticaj na žive sisteme, ali i neograničeni izazovi za nauku. Monografija “Kako žive i umiru ćelije u nama” je po mnogo čemu jedinstvena. Multidisciplinarnim postupkom napravljen je sveobuhvatni prikaz složenosti ljudskog tela, kao i njegovo moguće funkcionisanje na ćelijskom mikro i nano nivou, odnosno na nivou molekula, atoma, nukleusa, protona itd. Priča je inspirisana Balaševićevom crticom između godine rođenja i godine smrti.

Ključne reči: život ćelije, ćelijska smrt, matične ćelije, mozak, DNK, večnost života

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