Zaštita materijala 2. 2019

 

Inhibitive behavior of Ambrosia Maritima extract as an eco-friendly corrosion inhibitor for carbon steel in 1M HCl

Abstract

The inhibition effect of Ambrosia Maritima, which also named after (Damsissa) extract, towards the corrosion of carbon steel in 1M HCl solution was investigated utilizing potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) methods. The process of adsorption obeyed Langmuir adsorption isotherm. Damsissa extract was found to act as a mixed-type in 1M HCl. The computed adsorption thermodynamic parameters demonstrated that the adsorption was a spontaneous, endothermic process accompanied by an increase in the entropy. The maximum value of the inhibition approached 92.6% within the presence of 300 ppm Damsissa extract utilizing Tafel polarization procedure. The results obtained from the various electrochemical processes were in a great agreement. The inhibition of the extract was assumed to occur through the adsorption of active ingredients on the metal surface. Morphology of the surface was analyzed utilizing scanning electron microscopy (SEM), Fourier transforms infrared (FTIR) and atomic force microscopy (AFM) which confirmed the presence of a protective film of extract molecule on carbon steel 1018 surface.

Keywords: Ambrosia Maritima (Damsissa), Carbon Steel 1018, HCl, AFM, SEM.

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Inhibitorno ponašanje ekstrakta Ambrosia Maritima kao inhibitora korozije za ugljenični čelik u 1M HCl

Izvod

Ispitivan je efekat inhibicije Ambrosia Maritima, koji je, takođe, dobio ime po Damssisa ekstraktu, prema koroziji ugljeničnog čelika u 1M rastvoru HCl, koristeći metodu potenciodinamičke polarizacije, elektrohemijsku impedansnu spektroskopiju (EIS) i metodu EFM. Proces adsorpcije prati Langmirovu adsorpcionu izotermu. Nađeno je da ekstrakt deluje kao mešani tip inhibitora u 1M HCl. Proračunati adsorpcioni termodinamički parametri pokazali su da je adsorpcija spontani, endotermni proces praćen povećanjem entropije. Maksimalna vrednost inhibicije dostigla je 92,6% u prisustvu ekstrakta od 300 ppm, korišćenjem Tafelove polarizacione krive. Rezultati dobijeni iz različitih elektrohemijskih postupaka bili su u velikoj saglasnosti. Pretpostavlja se da se inhibicija ekstrakta odvija kroz adsorpciju aktivnih sastojaka na površini metala. Morfologija površine analizirana je pomoću skenirajuće elektronske mikroskopije (SEM), FTIR i atomske mikroskopije (AFM), koja je potvrdila prisustvo zaštitnog filma ekstraktnog molekula na površini ugljeničnog čelika 1018.

Ključne reči: Ambrosia Maritima, Damssisa, ugljenični čelik 1018, HCl, AFM, SEM.

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Mechanical properties and microstructure of the ZrO₂5CaO/NiCrAl coating system

Abstract

ZrO₂5CaO is a versatile class of material that can be sintered or plasma spray deposited in combination with other materials on the implant substrate. Due to brittleness the organic ceramic hydroxyapatite Ca₁₀(PO₄)₆ (OH)₂ – (HA) is not suitable for use as a separate material in the process of making implants. In order to improve the mechanical characteristics and osteoconductivity, to HA ceramics added are dual systems of oxide solid solutions, of which one is also ZrO₂5CaO. Ceramics ZrO₂-CaO(95%-5%) as a biomaterial facilitates osteoconductivity in new bone formation around the implant. This paper represents the need to develop a system of ZrO₂5CaO/NiCrAl coatings that will with their mechanical and structural characteristics find application on implant parts. In this context, using the atmospheric plasma spray process deposited were the ZrO₂5CaO/NiCrAl coatings system on stainless steel substrates X15Cr13 (EN 1.4024). Analysis of the morphology of the powder particles and the surface of the ZrO₂5CaO coatings was carried out on the SEM. The microstructure of the layers of the coatings system was analyzed on the OM. Mechanical properties of the coating were determined by examining the microhardness using the HV_0.3 method and bond strength by tensile testing according to the standard (ASTMC633-1).

Keywords: APS – atmospheric plasma spraying, NiCrAl, ZrO₂5CaO, microstructure, interface, microhardness, bond strength.

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Mehaničke osobine i mikrostruktura sistema prevlaka  ZrO₂5CaO/NiCrAl

Izvod

ZrO₂5CaO je višenamenska klasa materijala koja može da se sinteruje ili plazma sprej deponuje u kombinaciji sa drugim materijalima na podlogama implantata. Zbog krtosti organska keramika hidroksiapatit Ca₁₀(PO₄)₆(OH)₂ – (HA) nije pogodna za primenu kao zaseban materijal u procesu izrade implantata. U cilju poboljšanja osteokonduktivnosti i mehaničkih karakteristika, keramici HA se dodavaju dvojni sistemi čvrstih rastvora oksida od kojih je jedan i ZrO₂5CaO. Keramika ZrO₂-CaO(95%-5%) kao biomaterijal olakšava osteokonduktivnost u novom formiranju kostiju oko implantata. Ovaj rad predstavlja potrebu za izradom sistema ZrO₂5CaO/NiCrAl prevlaka koje će po svojim mehaničkim i strukturnim karakteristikama naći primenu na delovima implantata. U tom kontekstu atmosferskim plazma sprej procesom deponovan je sistem prevlaka ZrO₂5CaO/NiCrAl na čeličnim podlogama od nerđajućeg čelika X15Cr13 (EN 1.4024). Analiza morfologije čestica praha i površine prevlaka ZrO₂5CaO sprovedena je na SEM-u. Mikrostruktura slojeva sistema prevlaka ispitana je na OM-u. Mehaničke karakteristike prevlaka su sprovedene ispitivanjem mikrotvrdoće metodom HV_0.3 i čvrstoće spoja ispitivanjem na zatezanje po standardu (ASTMC633-1).

Ključne reči: APS – atmosferski plazma spreing, NiCrAl, ZrO₂5CaO, mikrostruktura, interfejs, mikrotvrdoća, čvrstoća spoja.

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Assessment of microbial diversity of soil exposed to nicosulfuron

Abstract

Nicosulfuron belongs to the sulfonylurea pesticides, which are widely used for weeds control. Except of benefits in plant production, long-term application of nicosulfuron may have toxic effect for living organisms, including microorganisms. The aim of this paper was to determined impact of nicosulfuron on microbial diversity of soil. Sampling of soil (0-20 and 20-40 cm) treated with nicosulfuron at village Trenica (Novi Travnik municipality, Bosnia and Herzegovina) was performed in autumn 2017. Determination of microbial diversity (total number of bacteria, ammonification bacteria, fungi and actinomycetes) was performed using standard methodology, whilst nicosulfuron-tolerant bacteria were isolated using enrichment method. Soil without nicosulfuron application was used as a control.

The results showed that bacteria were most abundant microbial population. In all experiments, reduction of microbial diversity in nicosulfuron-treated soil compared to untreated was observed. This reduction was most expressed in fungal number, which is reduced from 38 to 60% compared to control.

Several nicosulfuron-tolerant isolates were isolated by enrichment method. By microscopic observation and using API test kits and APIWEB database, isolates 17cs, and 22wl and 5 wl were identified as Pseudomonas fluorescens, and Bacillus subtilis, respectively. These bacterial isolates could be applied in remediation of environments polluted by nicosulfuron.

Keywords: microbial diversity, nicosulfuron, Bacillus, Pseudomonas.

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Ispitivanje mikrobnog diverziteta zemljišta tretiranog nikosulfuronom

Izvod

Nikosulfuron pripada grupi pesticide sulfonil urea, koji imaju široku primenu u uništavanju korova. Iako je njegova primena korisna sa aspekta uspešne biljne proizvodnje, njegova višegodišnja upotreba može imati toksične efekte za živi svet, uključujući i mikroorganizme. Cilj ovog rada bio je ispitivanje uticaja nikosulfurona na mikrobni diverzitet zemljišta. Uzorkovanje zemljišta (0-20 i 20-40 cm) tretiranog nikosulfuronom na području sela Trenica (Opština Novi Travnik, Bosna i Hercegovina) obavljeno je u jesen 2017. godine. Određivanje mikrobnog diverziteta (ukupnog broja bakterija, amonifikatora, gljiva I aktinomiceta) izvršeno je korišćenjem standardnih metoda, dok su bakterije tolerantne na prisustvo nikosulfurona određene metodom obogaćenja. Kontrolu je predstavljalo zemljište koje nije tretirano nikosulfuronom.

Rezultati ukazuju da su bakterije bile najbrojnija populacija mikroorganizama. U svim varijantama ogleda konstatovana je redukcija mikrobnog diverziteta u zemljištu koje je tretirano nikosulfuronom u odnosu na kontrolni uzorak. Stepen redukcije bio je najveći kod gljiva, čija je brojnost redukovana za 38-60% u odnosu na kontrolu.

Nekoliko izolata bakterija tolerantnih na prisustvo nikosulfurona je izolovano iz uzoraka zemljišta metodom obogaćenja. Mikroskopskim ispitivanjem I pomoću API i APIWEB metode, izolati 17cs, odnosno 22wl i 5wl, su identifikovani kao Pseudomonas fluorescens, odnosno Bacillus subtilis. Ovi bakterijski izolati bi mogli da imaju potencijalnu primenu u remedijaciji ekosistema kontaminiranih nikosulfuronom.

Ključne reči: mikrobni diverzitet, nikosulfuron, Bacillus, Pseudomonas.

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Influence of methyl methacrylate as an acrylic binder on a green machining of alumina ceramics

Abstract

Investigated the possibility of using methyl methacrylate (MMA) as an acrylic binder in the preparation of ceramic powder of alumina for pressing with the intention of improving machinability of alumina flakes. Compared the properties of the green bodies and the properties of their corresponding sintered samples that are prepared with and without acrylic binder. The achieved higher density of green bodies with MMA (2.35 g/cm³) compared to green bodies without MMA (2.11 g/cm³) were formed under the optimal pressure of 60 MPa, indicating the improved packing of alumina powder with addition of acrylate. In the case of sintered samples, the porosities were increased, and the density and percentage of linear shrinkage were reduced. It has been shown that machining of green bodies, prepared with MMA, can be produced in the form of complex ceramic products of alumina like a screw with a nut and with great possibilities of commercial application.

Keywords: alumina, acrylic binder, methyl methacrylate, green machining.

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Uticaj metil metakrilatoma kao akrilnog veziva na mašinsku obradljivost ispresaka alumine

Izvod

Ispitana je mogućnost primene metil metakrilata, MMA, kao akrilnog veziva u pripremi keramičkog praha alumine za presovanje sa namerom da se poboljša mašinska obradljivost ispresaka od alumine. Poređene su osobine ispresaka i osobine njima odgovarajućih sinterovanih uzoraka koji su pripremljeni sa i bez akrilnog veziva. Visoka gustina ispresaka sa MMA (2,35 g/cm³) u odnosu na ispreske samo od alumine (2,11 g/cm³) formiranih pod optimalnim pritiskom presovanja od 60 MPa, ukazuje na uticaj akrilata na poboljšano pakovanje praha alumine i njihovu odličnu mašinsku obradljivost; kod sinterovanih uzoraka povećana je poroznost, a smanjene su gustina i procenat linearnog skupljanja. Pokazano je da se mašinskom obradom ispresaka alumine sa MMA, mogu napraviti složene forme poput keramičkog zavrtnja ili keramički delovi sklopova, sa velikim mogućnostima komercijalne primene.

Ključne reči: alumina, akrilna veziva, metil metakrilat, mašinska obradljivost ispresaka.

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Impact of TNT explosive and its degradation  products on the environment

Abstract

Explosive is a device or substance that, when exposed to heat, shock, friction or detonation, quickly releases a large amount of energy. In the event of a sudden release of energy, there is an increase in temperature and pressure, and the entire explosive material turns into hot compressed gases that spread rapidly and thus produce a pressure wave, i.e. “impact wave”. Trinitrotoulene explosive (TNT) is military explosive with wide application, and therefore the largest input of explosives in the environment comes from military activities. Munition used in both military and civilian uses contaminates all parts of the world. TNT is poorly degradable and can be found in low concentrations in soil, surface waters and underground waters. Unfortunately, not only TNT is harmful but also its degradation products. Explosive compounds adversely affect different types of soil, water, plants, animals, and also humans. Impact of explosives contamination degree is different for each living being. The remediation of contaminated areas can be done by various physical, chemical and biological methods.

Keywords: TNT explosives, TNT’s impact, TNT’s degradation products, environment.

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Uticaj TNT eksploziva i njegovih produkata degradacije na životnu sredinu

Izvod

Eksploziv je supstanca koja kada je izložena toploti, udaru, trenju ili detonaciji, veoma brzo oslobađa veliku količinu energije. Prilikom naglog oslobađanja energije, dolazi do povećanja temperature i pritiska i čitav eksplozivni materijal se pretvara u vruće kompresovane gasove koji se brzo šire i na taj način iniciraju talas pritiska, tj. “udarni talas”. Eksploziv trinitrotoluen (TNT) je vojni eksploziv široke primene, i samim tim najveći unos eksploziva u životnu sredinu dolazi iz vojnih aktivnosti. Municija koja se koristi, kako u vojne, tako i u civilne svrhe, kontaminira sve delove sveta. TNT je slaborazgradiv i može se naći u niskim koncentracijama u zemljištu, površinskim i podzemnim vodama. Nažalost, nije štetan samo TNT, već i njegovi produkti degradacije. Eksplozivna jedinjenja negativno utiču na različite vrste zemljišta, voda, biljaka, životinja, a takođe i na čoveka. Stepen uticaja kontaminacije eksplozivom nije isti na sva živa bića. Sanacija zagađenih područja može se vršiti različitim fizičkim, hemijskim i biološkim metodama.

Ključne reči: TNT eksploziv, uticaj TNT-a, produkti degradacije TNT-a, životna sredina.

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Analysis of the heat affected zone in plasma jet cutting process of the aluminium alloy EN AW 5083

Abstract

Plasma jet cutting process is a well-known nonconventional thermo-electrical manufacturing process that is widely used in metal and shipbuilding industry. It uses the energy of highly ionized gas to cut various types of metal materials. Cutting process is determined by technological parameters whose values define the final cut quality results. Cut quality can be defined considering different characteristics such as: kerf width, bevel angle, surface roughness, dross height and heat affected zone. In this paper, a research on the influence of variable process parameters on the heat affected zone (HAZ) was conducted. An investigated material was aluminium alloy EN AW 5083. HAZ analysis was done by measuring hardness changes on the specimen cross sections and by microscopic observation of the material structure.

Keywords: plasma jet cutting, heat affected zone, aluminium, EN AW 5083, hardness, material structure.

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Analiza zone uticaja topline kod plazma rezanja na leguri aluminija  EN AW 5083

Izvod

Rezanje plazmom je poznati nekonvencionalni termo-električni proizvodni postupak koji se ponajviše koristi u metalnoj i brodograđevnoj industriji. Postupak koristi energiju visoko ioniziranog plina za rezanje različitih tipova metalnih materijala. Postupak rezanja je definiran tehnološkim parametrima čije vrednosti određuju kvalitetu završnog reza. Kvaliteta reza može se definirati različitim karakteristikama, kao što su: širina reza, kut nagiba, površinska hrapavost, visina srha i zona uticaja topline. U ovom radu provedeno je istraživanje delovanja različitih parametara procesa na zonu uticaja topline (ZUT). Ispitivani materijal je bila legura aluminija EN AW 5083. Analiza zone uticaja topline izvršena je merenjem promene tvrdoće po poprečnom preseku uzoraka i mikroskopskom analizom strukture materijala.

Ključne reči: plazma rezanje, zona uticaja topline, aluminij, EN AW 5083, tvrdoća, struktura materijala.

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Formation and development of damage of basalt under the effect of cavitation

Abstract

The paper examines the cavitation resistance of the cast basalt samples. Samples were obtained by melting, casting and thermal treatment of crushed basalt rocks from the Vrelo Kopaonik deposit. The experiment was conducted using an ultrasonic vibration method with a stationary sample according to the ASTM G-32 standard. To estimation the cavitation resistance, a change in the mass of the samples in the function of the cavitation time has been observed. The formation and development of damage under the effect of cavitation was monitored by an electron microscope, and the level of degradation of the sample surface was quantified using the image analysis. The results showed a high degree of cavitation resistance of cast basalt samples, with a cavitation rate of 0.0294 mg/min. This indicates the possibility of their application for the production of particular structural parts of equipment for use in metallurgy, as a substitute for metallic materials.

Keywords: basalt, cavitation damage, mass loss, image analysis.

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Nastajanje i razvoj oštećenja bazalta pod dejstvom kavitacije

Izvod

U radu je ispitivana otpornost na dejstvo kavitacije uzoraka livenog bazalta. Uzorci su dobijeni topljenjem, livenjem i termičkim tretmanom izdrobljenih bazaltnih stena iz ležišta Vrelo Kopaonik. Eksperiment je vođen primenom ultrazvučne vibracione metode sa stacionarnim uzorkom prema standardu ASTM G-32. Za procenu otpornosti na dejstvo kavitacije praćena je promena mase uzoraka u funkciji vremena delovanja kavitacije. Nastajanje i razvoj oštećenja pod dejstvom kavitacije praćeni su skening elektronskim mikroskopom, a nivo degradacije površine uzoraka kvantifikovan je primenom analize slike. Rezultati su pokazali visok stepen otpornosti na dejstvo kavitacije uzoraka livenog bazalta, sa kavitacionom brzinom 0,0294 mg/min. To ukazuje na mogućnost njihove primene za izradu izvesnih konstrukcionih delova opreme za primenu u metalurgiji, kao zamena za metalne materijale.

Ključne reči: bazalt, oštećenje pod dejstvom kavitacije, gubitak mase, analiza slike.

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Overview of diffusion boriding  problems in industrial applications

Abstract

In this paper is systematized a review of the problem which occur during the execution of the boriding process, and which by its occurrence limit its wider and versatile industrial application. The paper focuses on all defects that undermine the integrity of the boride layer and which affect on the reduction of its safety in severe exploitation conditions. The research was directed towards the display of limitations and inadequacy of boriding procedures in a solid, liquid and gaseous medium in terms of their contribution to low production efficiency and unjustifiably high production costs. The adverse effects of brittleness and formation of cracks that lead to fracture and peeling of the boric layer were considered, the problems of choosing high process temperatures which can be harmful for the base material, but also other errors which to be avoided in order to achieve the optimum characteristics of the boride layers. Remaining in this context, special attention was paid to the frequent factors that have the greatest impact on the deterioration of the mechanical properties of boride layers, especially dynamic strength and toughness.

Keywords: boronizing, brittleness, cracks, toughness, temperature.

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Pregled problema difuzionog boriranja u industrijskoj primeni

Izvod

U ovom radu, sistematizovan je pregled problema koji se javljaju prilikom izvođenja postupka boriranja, a koji svojom pojavom ograničavaju njegovu širu i svestraniju industrijsku primenu. U radu je skrenuta pažnja na sve nedostatke koji narušavaju integritet boridnog sloja i koji utiču na smanjenje njegove pouzdanosti u teškim eksploatacionim uslovima. Istraživanja su bila usmerena u pravcu prikazivanja ograničenja i neadekvatnosti postupaka boriranja u čvrstom, tečnom i gasovitom sredstvu u smislu njihovog doprinosa niskoj efikasnosti proizvodnje i neopravdano visokim troškovima proizvodnje. Razmotreni su nepovoljni uticaji krtosti i formiranja pukotina koji dovode do loma i do ljuštenja boridnog sloja, problemi izbora visokih temperatura procesa koje mogu štetno delovati na osnovni materijal, ali i ostale greške koje se trebaju izbeći u cilju postizanja optimalnih karakteristika boridnih slojeva. Ostajući u ovom kontekstu, posebna pažnja je posvećena učestalim faktorima koji imaju najveći uticaj na pogoršanje mehaničkih osobina boridnih slojeva, posebno dinamičke čvrstoće i žilavosti.

Ključne reči: boriranje, krtost, pukotine, žilavost, temperature.

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The green modification of Lagenaria vulgaris agro-waste: spectroscopic and morphological analysis

Abstract

Recently, research on the exploitation and conversion of agricultural residues into value added products for the production of various important biomolecules of economic importance has been actively implemented. Therefore, the modification of bottle gourd (Lagenaria vulgaris) shell (BGS), as a potentially valuable agro-waste, by a green carbonate treatment has been analyzed in this study. The biochemical composition, structural and morphological changes of BGS biomass during the treatment were monitored using physicochemical, spectroscopic (FTIR) and microscopic (SEM) methods. The partial delignification and removal of extractive substances from the lignocellulosic biomass, such as oligosaccharides of depolymerized hemicellulose, organic acids, lignin fragments, and possibly trapped minerals have been disclosed. In this way, increased porosity of the cellulose enriched BGS biomass, as well as the activation of cellulosic microfibrils to alkaline-cellulose has been achieved. It was found that these changes are an important prerequisite for making a precursor of biosorbent which can be applied in wastewater treatment technology.

Keywords: bottle gourd, lignocellulosic biomass, modification, green solution, FTIR, SEM.

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Zelena modifikacija Lagenaria vulgaris agro-otpada: spektroskopska i morfološka analiza

Izvod

U poslednje vreme aktivno se provode istraživanja o iskorišćenju i konverziji poljoprivrednih ostataka u proizvode sa dodatom vrednošću za dobijanje različitih važnih biomolekula od ekonomskog značaja. Stoga je u ovoj studiji analizirana modifikacija kore tikve sudovnjače (Lagenaria vulgaris), kao potencijalno vrednog poljoprivrednog otpada, zelenim karbonatnim tretmanom. Biohemijski sastav, strukturne i morfološke promene biomase kore tikve tokom tretmana praćene su pomoću fizičko-hemijskih, spektroskopskih (FTIR) i mikroskopskih (SEM) metoda. Otkrivena je delimična delignifikacija i uklanjanje ekstraktivnih supstanci iz lignocelulozne biomase, kao što su oligosaharidi depolimerizovane hemiceluloze, organske kiseline, fragmenti lignina i eventualno zarobljeni minerali. Na ovaj način postignuta je povećana poroznost celulozom obogaćene biomase, kao i aktivacija celuloznih mikrofibrila u alkalnu celulozu. Utvrđeno je da su ove promene važan preduslov za izradu prekursora biosorbenta koji se može primeniti u tehnologiji tretmana otpadnih voda.

Ključne reči: tikva sudovnjača, lignocelulozna biomasa, modifikacija, zeleni rastvor, FTIR, SEM.

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