Abd El-Aziz S. Fouda *1, Aya M.Salem2, Ahmed M. Wahba3, Samir A. Abd El-Maksous4, Mahmoud N. EL-Haddad1
1Mansoura University, Department of Chemistry, Faculty of Science, Mansoura- 35516, Egypt, 2Department of Basic Science, Higher Institute of Electronic Engineering (HIEE), Belbis, Egypt, 3Department of Basic Science, Higher Institute of Engineering and Technology (HIET), El-Mahalla, Egypt, 4Port Said University, Department of Chemistry, Faculty of Science, Port Said, Egypt
Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
https://doi.org/10.5937/zasmat2303239F
Zastita Materijala 64 (3)
239 – 255 (2023)
Experimental and theoretical optimization of Chelidonium Majus (Papaveraceae) extract as an environmentally friendly inhibitor for corrosion of α-brass in nitric acid solution
Abstract
The research paper discusses the study of the inhibition rates of Chelidonium Majus (Papaveraceae) plant extract (CME) on α- brass in 1.0 M HNO3 solution. The study was carried out using chemical and electrochemical techniques, which showed results of up to 97% inhibition with 150 ppm at 250C. For the polarization results, CME is a mixed-type inhibitor. The increase in the charge transfer resistance and the decrease in the capacitance of the double layer with increasing concentration were observed by Nyquist diagrams and it was found that the inhibition process follows the Langmuir isotherm which proves the formation of a monolayer on the surface of the α- brass. Quantum chemical calculations were performed using the DFT method to determine the active centres of the CME which responsible for adsorption, as well, to their possible interaction mechanism with the- brass surface.
Keywords: Corrosion inhibition, α- brass, HNO3, Chelidonium Majus extract, DFT.
Eksperimentalna i teorijska optimizacija ekstrakta chelidonium majus (papaveraceae) kao ekološki prihvatljivog inhibitora korozije α-mesinga u rastvoru azotne kiseline
Izvod
U radu se razmatra proučavanje nivoa inhibicije biljnog ekstrakta Chelidonium Majus (Papaveraceae) (CME) na α-mesingu u 1,0M rastvoru HNO3. Studija je sprovedena primenom hemijskih i elektrohemijskih tehnika, koje su pokazale rezultate do 97% inhibicije sa 150 ppm na 2500C. Za rezultate polarizacije, CME je inhibitor mešovitog tipa. Povećanje otpora prenosa naelektrisanja i smanjenje kapacitivnosti dvostrukog sloja sa povećanjem koncentracije primećeno je Nyquist-ovim dijagramima i utvrđeno je da proces inhibicije prati Langmirovu izotermu koja dokazuje formiranje monosloja na površini α-mesing. Kvantno hemijski proračuni su izvršeni DFT metodom za određivanje aktivnih centara CME koji su odgovorni za adsorpciju, kao i za njihov mogući mehanizam interakcije sa mesinganom površinom.
Ključne reči: Inhibicija korozije, α- mesing, HNO3, ekstrakt Chelidonium Majus, DFT
Lev Chernyak*, Natalia Dorogan, Liubov Melnyk,Petro Varshavets, Victoria Pakhomova
National Technical University of Ukraine ” Igor Sikorsky Kyiv“, Polytechnic Institute, Kyiv, Ukraine
Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
https://doi.org/10.5937/zasmat2303256C
Zastita Materijala 64 (3)
256 – 261 (2023)
Analysis of white cement production during low-temperature firing
Abstract
The possibility to produce white Eco-cement with the use of a dry method under low-temperature firing of a raw material mixture based on the CaO – SiO2 – AL2O3 – MgO system is shown. Computer calculations were performed and an analysis of the dependence of the characteristics of cement clinker on the quantitative ratio of raw components was carried out. A new composition of the raw material mixture with a decrease of 19 wt. % amount of the carbonate component and, accordingly, CO2 emissions during combustion was determined. The peculiarities of phase transformations in the material during firing with a maximum temperature of 1100 °С when microtalcum was introduced into the initial mixture with the formation of pericloze, ockermanite and merwinite as a factor in the structure and properties of cement clinker were noted.
Key words: Еco-cement,raw material mixture, microtalc, firing, phase composition, properties.
Analiza proizvodnje belog cementa pri niskotemperaturnom pečenju
Izvod
Prikazana je mogućnost proizvodnje belog ekocementa primenom suve metode pri niskotemperaturnom pečenju sirovinske mešavine po sistemu CaO – SiO2 – AL2O3 – MgO. Urađeni su kompjuterski proračuni i izvršena je analiza zavisnosti karakteristika cementnog klinkera od kvantitativnog odnosa sirovih komponenti. Novi sastav mešavine sirovina sa smanjenjem od 19 tež. % količina karbonatne komponente i shodno tome određena je emisija CO2 pri sagorevanju. Uočene su osobenosti faznih transformacija u materijalu pri pečenju sa maksimalnom temperaturom od 1100°C pri uvođenju mikrotalkuma u početnu smešu sa formiranjem perikloza, okermanita i mervinita kao faktora u strukturi i svojstvima cementnog klinkera.
Ključne reči: ekocement, mešavina sirovina, mikrotalk, pečenje, fazni sastav, svojstva.
Leonid Dvorkin*, Vadim Zhitkovsky
National University of Water and Environmental Engineering, Rivne, Ukraine
Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
https://doi.org/10.5937/zasmat2303262D
Zastita Materijala 64 (3)
262 – 273 (2023)
Concretes based on composite cements with the addition of granulated blast furnace slag and cement dust
Abstract
A set of experimental-statistical models has been obtained that makes it possible to predict the workability and strength of concrete on a composite binder, including the addition of dust from cement clinker kilns and granulated blast-furnace slag, as well as polycarboxylate superplasticizer Sika VC 225.
The values of the critical water-cement ratio are determined, which determine the area of constant water demand and take into account the binder normal consistency, as well as the adsorption coefficients of fine and coarse aggregates.
Experimental-statistical models of the coefficients that determine the yield of concrete strength per 1 kg of composite cement and Portland cement Cem I contained in it are obtained.
Keywords: cement kiln, dust, granulated blast-furnace slag, composite cement, concrete, experimental-statistical model.
Betoni na bazi kompozitnih cementa sa dodatkom granulisane visokopećne šljake i cementne prašine
Izvod
Dobijen je set eksperimentalno-statističkih modela koji omogućavaju predviđanje obradivosti i čvrstoće betona na kompozitnom vezivu, uključujući dodavanje prašine iz peći cementnog klinkera i granulisane šljake visoke peći, kao i polikarboksilatnog superplastifikatora Sika VC. 225.
Određene su vrednosti kritičnog vodocementnog odnosa koje određuju oblast konstantne potražnje za vodom i uzimaju u obzir normalnu konzistenciju veziva, kao i koeficijente adsorpcije finih i krupnih agregata.
Dobijeni su eksperimentalno-statistički modeli koeficijenata koji određuju prinos čvrstoće betona po 1 kg kompozitnog cementa i portland cementa Cem I koji se u njemu nalazi.
Ključne reči: cementna peć, prašina, granulisana visokopećna šljaka, kompozitni cement, beton, eksperimentalno-statistički model
Agha Inya Ndukwe1*, Nsikan Etim Dan1, Justus Uchenna Anaele1, Christopher Chibuike Ozoh1, Kooffreh Okon1,2, Paulinus Chukwudi Agu1
1Federal University of Technology, Department of Materials and Metallurgical Engineering, Owerri, Imo State, Nigeria, 2Federal University of Technology, African Centre of Excellence in Future Energies and Electrochemical Systems, Owerri (ACE-FUELS, FUTO), Imo State, Nigeria
Review paper
ISSN 0351-9465, E-ISSN 2466-2585
https://doi.org/10.5937/zasmat2303274N
Zastita Materijala 64 (3)
274 – 282 (2023)
The inhibition of mild steel corrosion by papaya and neem extracts
Abstract
This study examined earlier research on using papaya and neem extracts as inhibitors to minimize the corrosion of mild steel in a variety of corrosive situations. The potential inhibitory characteristics of plant extracts to potentially replace the hitherto used, well-known inhibitors that are harmful to the people handling them as well as the environment, inspired several scholars to conduct corrosion inhibition tests on metals using plant extracts. The findings of earlier research demonstrated that the maximal inhibitory efficiency provided by neem leaf extract to prevent the degradation of carbon steel in a hydrochloric acid (1 M) medium was 97%, while 86% was observed for the protection in H2SO4 (1 M) solution. The extract from Carica papaya leaves was shown to have up to 83% maximum inhibitory efficacy for preventing mild steel corrosion in HCl (1 M). It has been revealed that when extract concentration increased, the rate of steel corrosion reduced. Additionally, papaya leaves’ corrosion-inhibiting mechanism was said to occur mostly in the cathodic area. Both plant-leaf extracts (Papaya and Neem) have been reported to have adsorption qualities that, for the most part, agreed with the Langmuir adsorption isotherm model.
Keywords: corrosion inhibition, papaya, neem, plant extracts, mild steel.
Inhibicija korozije mekog čelika ekstraktom papaje i nima
Izvod
Ova studija je ispitala ranija istraživanja o korišćenju ekstrakta papaje i nima kao inhibitora da bi se smanjila korozija mekog čelika u različitim korozivnim situacijama. Potencijalne inhibitorne karakteristike biljnih ekstrakata da potencijalno zamene do sada korišćene, dobro poznate inhibitore koji su štetni za ljude koji njima rukuju, kao i za životnu sredinu, inspirisali su nekoliko naučnika da sprovedu testove inhibicije korozije na metalima koristeći biljne ekstrakte. Nalazi ranijih istraživanja su pokazali da je maksimalna inhibitorna efikasnost koju je obezbedio ekstrakt lista nima za sprečavanje razgradnje ugljeničnog čelika u medijumu sa hlorovodoničnom kiselinom (1 M) bila 97%, dok je 86% primećeno za zaštitu u H2SO4 (1 M) rešenje. Pokazalo se da ekstrakt iz listova papaje Carica ima do 83% maksimalne inhibitorne efikasnosti za sprečavanje blage korozije čelika u HCl (1 M). Otkriveno je da kada se koncentracija ekstrakta poveća, stopa korozije čelika se smanjuje. Pored toga, rečeno je da se mehanizam koji sprečava koroziju korišćenjem listova papaje javlja uglavnom u katodnoj oblasti. Prijavljeno je da oba ekstrakta listova biljaka (papaja i nima) imaju adsorpcione kvalitete koje se, uglavnom, slažu sa modelom izoterme adsorpcije Langmuir.
Ključne reči: inhibicija korozije, papaja, nim, biljni ekstrakti, meki čelik.
LiudmilaTsygankova1*, Marina Uryadnikova1,Lyudmila Rodionova1, Natalia Shel2, Olga Alekhina1
1Derzhavin State University, Tambov, Russian Federation, 2Tambov State Technical University, Tambov, Russian Federation
Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
https://doi.org/10.5937/zasmat2303283T
Zastita Materijala 64 (3)
283 – 290 (2023)
Protection of carbon steel against corrosion with a superhydrophobic coating
Abstract
Under atmospheric conditions at 100% humidity, a surface phase film of moisture is formed on the surface of metals, in which air microimpurities NH3, CO2, H2S, etc. are dissolved and almost completely hydrated with the formation of NH4OH and acids H2CO3 and H2S. The method of potentiodynamic polarization has been used to study the protective efficiency of a superhydrophobic coating on carbon steel in NaCl-based model media simulating saturation of the surface moisture film with carbon dioxide (IV) and/or ammonia under atmospheric conditions. Similar studies were carried out with uncoated electrodes. The superhydrophobic coating was obtained on the basis of laser texturing of the steel surface followed by hydrophobization with fluoroxysilane (wetting angle 165±2°, rolling angle 3±1°). The influence of the duration of exposure of electrodes in solution (0.25 – 168 h) on the kinetics of electrode processes, the rate of steel corrosion and the protective effectiveness of the superhydrophobic coating is considered. It has been shown that the presence of ammonium hydroxide or ammonium carbonate in solution increases the protective effectiveness of the coating compared to a purely chloride medium simulating harsh atmospheric conditions.
Keywords: carbon steel, corrosion, protection, superhydrophobic coating, contact angle, ammonia, carbon dioxide (IV),potentiodynamic polarization.
Zaštita ugljeničnog čelika od korozije superhidrofobnim premazom
Izvod
U atmosferskim uslovima pri 100% vlažnosti na površini metala se formira površinski fazni film vlage u kome se rastvore iskoro potpuno hidriraju vazdušne mikro nečistoće NH3, CO2, H2S itd. U atmosferskim uslovima pri 100% vlažnosti, na površini metala se formira površinski fazni film vlage u kome se nalaze mikro nečistoće vazduha NH3, CO2, H2S itd., koje se rastvore i skoro potpuno hidratizuju sa stvaranjem NH4OH i kiselina H2CO3 i H2S. Metoda potenciodinamičke polarizacije je korišćena za proučavanje zaštitne efikasnosti superhidrofobne prevlake na ugljeničnom čeliku u modelnom mediju na bazi NaCl koji simulira zasićenje filma površinske vlage ugljen-dioksidom (IV) i/ili amonijakom u atmosferskim uslovima. Superhidrofobni premaz je dobijen na osnovu laserskog teksturiranja čelične površine praćene hidrofobizacijom fluoroksisilanom (ugao vlaženja 165±2°, ugao kotrljanja 3±1°). Razmatran je uticaj trajanja izlaganja elektroda u rastvoru (0,25 – 168 h) na kinetiku elektrodnih procesa, brzinu korozije čelika i zaštitnu efikasnost superhidrofobnog premaza. Pokazalo se da prisustvo amonijum hidroksida ili amonijumkarbonata u rastvoru povećava zaštitnu efikasnost premaza u poređenju sa čisto hloridnim medijumom koji simulira oštre atmosferske uslove.
Ključne reči: ugljenični čelik, korozija, zaštita, superhidrofobni premaz, kontaktni ugao, amonijak, ugljen-dioksid (IV), potenciodinamička polarizacija.
Saša Papuga*, Aleksandra Kolundžija, Milica Đurđević
University of Banja Luka, Faculty of Technology, Banja Luka, Republic of Srpska
Review paper
ISSN 0351-9465, E-ISSN 2466-2585
https://doi.org/10.5937/zasmat2303291P
Zastita Materijala 64 (3)
291 – 299 (2023)
Biofuels as a challenge of sustainable development
Abstract
Bioenergy, or energy derived from biomass, today is recognized as an important component in many energy scenarios, being an integral part of various global, regional, and national policies and strategies. This has led to intensified research into more efficient biofuel production. This paper explains the advantages, disadvantages, and problems related to the production of biofuels from different types of raw materials. Several examples of commercialized and demonstration plants for the production of biofuels in different parts of the world are listed. It is to be expected that, with greater use of modern biofuel production solutions, the contribution of these sources of (bio)energy will be the main part of future energy consumption from renewable sources.
Keywords: biofuels, biomass, bioenergy, sustainability, energy policy.
Biogoriva kao izazov održivog razvoja
Izvod
Bioenergija, ili energija dobijena iz biomase, danas je prepoznata kao važna komponenta u mnogim energetskim scenarijima, kao sastavni dio različitih globalnih, regionalnih i nacionalnih politika i strategija. To je dovelo do intenziviranja istraživanja efikasnije proizvodnje biogoriva. U ovom radu se objašnjavaju prednosti, nedostaci i problemi vezani za proizvodnju biogoriva iz različitih vrsta sirovina. Navedeno je nekoliko primjera komercijaliziranih i demonstracionih postrojenja za proizvodnju biogoriva u različitim dijelovima svijeta. Za očekivati je da će, uz veću upotrebu savremenih rješenja za proizvodnju biogoriva, doprinos ovih izvora (bio)energije biti glavni dio buduće potrošnje energije iz obnovljivih izvora.
Ključne riječi: biogoriva, biomasa, bioenergija, održivost, energetska politika.
Dehenenet Flatie1, Tamrat Tesfaye1,2,3, Kayakada Murugesh Babu1*, Magdi Gibril3, Fangong Kong3
1Bahir Dar University, Textile Chemistry Research and Innovation Center, Ethiopian Institute of Textile and Fashion Technology, Bahir Dar, Ethiopia, 2Bahir Dar University, Biorefinery Research Center, Ethiopian Institute of Textile and Fashion Technology, Bahir Dar, Ethiopia, 3Qilu University of Technology, State Key Laboratory of Biobased Material and Green Papermaking, Jinan, Shandong, China
Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
https://doi.org/10.5937/zasmat2303300F
Zastita Materijala 64 (3)
300 – 307 (2023)
Bio-refining of cottonseed meal from oil industry for the isolation of eco-friendly natural protein polymer
Abstract
Cottonseed meal (CSM) is a by-product of the oil industry. Globulins (salt soluble, vicilin, and legumin families) are the major dominant storage proteins in cottonseed and account for 60%–70% of seed proteins. However, these are unsuitable for human consumption due to their gossypol content. In this work, protein was extracted from defatted cottonseed flour with alkaline solution and its precipitation at different pH value was investigated. The crude protein was quantified using standard micro-Kjeldahl nitrogen method. Central composite design expert was conducted and the effect of variables in the extraction of protein were studied, namely, extraction solvent concentration, temperature and time. The optimum scheme of extraction was obtained at 0.1M NaOH with material to liquor ratio (MLR) 1:20 at pH 12 using temperature of 67℃ and a time of 90 min. Under these conditions, the response gives a flour dissolution percentage of 80.52% and protein purity percentage 80.40%. In addition, protein solubility and water absorption capacity were also determined and the chemical structure of protein was characterized by means of Fourier Transform Infrared Spectroscopy.
Keywords: Cottonseed meal, Cottonseed protein, Cottonseed protein flour, Extraction, Protein characteristics, Precipitation
Bio-rafiniranje sačme pamučnog semena iz naftne industrije za izolaciju ekološki prihvatljivog prirodnog proteinskog polimera
Izvod
Sačma od semena pamuka (CSM) je nusproizvod naftne industrije. Globulini (familije rastvorljivih u soli, vicilina i legumina) su glavni dominantni proteini za skladištenje u semenu pamuka i čine 60-70% proteina semena. Međutim, oni su neprikladni za ljudsku ishranu zbog sadržaja gosipola. U ovom radu, protein je ekstrahovan iz odmašćenog pamučnog brašna alkalnim rastvorom i ispitivano je njegovo taloženje na različitim pH vrednostima. Sirovi protein je kvantifikovan korišćenjem standardne mikro-Kjeldahlove metode azota. Obavljen je centralni ekspert za dizajn kompozita i proučavan je uticaj varijabli na ekstrakciju proteina, odnosno koncentracije rastvarača za ekstrakciju, temperature i vremena. Optimalna šema ekstrakcije je dobijena na 0,1M NaOH sa odnosom materijala i tečnosti (MLR) 1:20 na pH 12 korišćenjem temperature od 67℃ i vremena od 90 min. Pod ovim uslovima, odgovor daje procenat rastvorljivosti brašna od 80,52% i procenat čistoće proteina 80,40%. Pored toga, utvrđena je rastvorljivost proteina i kapacitet apsorpcije vode, a hemijska struktura proteina je okarakterisana pomoću infracrvene spektroskopije Furijeove transformacije.
Ključne reči: brašno od pamučnog semena, protein semena pamuka, proteinsko brašno semena pamuka, ekstrakcija, karakteristike proteina, precipitacija
Subrata Das*1, Amitabh Wahi2, Suresh Jayaram3
1Department of Fashion Technology, Bannari Amman Institute of Technology, Sathyamangalam, Erode Dist., Tamil Nadu, India, 2Bhagwant University, Department of Computer Science & Engineering, Ajmer, Rajasthan, India, 3Sky Cotex India Private Limited, Tirupur, Tamil Nadu, India
Scientific paper
ISSN 0351-9465, E-ISSN 2466-2585
https://doi.org/10.5937/zasmat2303308D
Zastita Materijala 64 (3)
308 – 313 (2023)
Defect detection in textiles using back propagation neural classifier
Abstract
The textile products are affected by the defects during the manufacturing processes. It is also waste of the resources used for the production and in turn it affects the business. The manual inspection in defect detections is not encouraged these days in manufacturing process. The computer vision with machine learning algorithms in automated quality control system plays an important role in detecting defects in manufacturing process as well as analyzing the quality of products. Classification of defects in knitted fabric is an active area of research around the globe. This paper presents a classification method to detect defects such as holes and thick places in knitted fabric by applying artificial neural network algorithm. The artificial neural network algorithms learn from the input data after successful training process, it predicts the nature of the unknown samples in very fast and accurate way. The proposed work has been carried out in two phases. In the first phase the images of the defective samples of two classes were collected by a high-resolution camera. The color images of the samples were converted into grey scale images. The features were extracted from each grey scale image and stored in a database. In the second phase a neural classifier was trained with back–propagation neural Network (BPNN) algorithm on the training dataset. After successful training of the neural network on train dataset, the performance of the trained neural network was evaluated on the test dataset. Different experiments were carried out by increasing the number of training data samples; it was found that the best evaluation performance was obtained as 83.3%.
Keywords: Classification of defects, holes, thick places, artificial neural network, features, knitted fabrics.
Detekcija defekta u tekstilu korišćenjem neuronskog klasifikatora sa povratnim širenjem
Izvod
Tekstilni proizvodi su pogođeni defektima tokom procesa proizvodnje. To je, takođe, rasipanje resursa koji se koriste za proizvodnju i zauzvrat utiče na poslovanje. Ručna inspekcija u otkrivanju kvarova se danas ne podstiče u proizvodnom procesu. Kompjuterski vid sa algoritmima mašinskog učenja u automatizovanom sistemu kontrole kvaliteta igra važnu ulogu u otkrivanju nedostataka u proizvodnom procesu, kao i analizi kvaliteta proizvoda. Klasifikacija nedostataka pletene tkanine je aktivna oblast istraživanja širom sveta. Ovaj rad predstavlja metod klasifikacije za otkrivanje nedostataka kao što su rupe i debela mesta na pletenini primenom algoritma veštačke neuronske mreže. Algoritmi veštačke neuronske mreže uče iz ulaznih podataka nakon uspešnog procesa obuke, predviđa prirodu nepoznatih uzoraka na veoma brz i precizan način. Predloženi radovi se odvijaju u dve faze. U prvoj fazi su slike neispravnih uzoraka dve klase prikupljene kamerom visoke rezolucije. Slike uzoraka u boji su pretvorene u slike u sivoj skali. Karakteristike su izvučene iz svake slike u sivoj skali i uskladištene u bazi podataka. U drugoj fazi je obučen neuronski klasifikator sa algoritmom neuronske mreže sa povratnom propagacijom (BPNN) na skupu podataka za obuku. Nakon uspešne obuke neuronske mreže na skupu podataka o vozu, performanse obučene neuronske mreže su procenjene na test skupu podataka. Različiti eksperimenti su sprovedeni povećanjem broja uzoraka podataka za obuku; utvrđeno je da je najbolji učinak ocenjivanja dobijen sa 83,3%.
Ključne reči: Klasifikacija defekata, rupe, debela mesta, veštačka neuronska mreža, karakteristike, pletenine
Redžo Hasanagić1*, Leila Fathi2, Atif Hodžić1, Mohsen Bahmani2
1University of Bihać, Department of Wood Science and Technology, Technical Faculty, Bihać, Bosnia and Herzegovina, 2Shahrekord University, Department of Natural Resources and Earth Science, Shahrekord, Iran
Review paper
ISSN 0351-9465, E-ISSN 2466-2585
https://doi.org/10.5937/zasmat2303314H
Zastita Materijala 64 (3)
314- 326 (2023)
Physical and mechanical changes in thermal modified wood: A review
Abstract
In Europe, wood is a crucial construction material that has experienced a surge in use for building applications in recent years. To enhance its dimensional stability and durability, thermal modification is a widely accepted commercial technology. Thermal modification is a popular technique that alters the properties of wood, improving its resistance to decay and increasing its dimensional stability. The process involves heating wood to high temperatures under controlled conditions, leading to chemical reactions that result in various physical and mechanical changes. This paper will discuss the effects of thermal modification on the physical properties of wood, such as density, moisture content, and color, as well as its impact on the mechanical properties, including strength, stiffness, and hardness. Additionally, the review will examine the factors that influence the degree of modification, such as temperature, duration, and wood species. Finally, the paper will conclude with an overview of the current state of research in this field and identify potential avenues for future investigation.
Keywords: Wood, mass loss, modul of elasticity, construction, commercial, technology.
Fizičke i mehaničke promene u termo modifikovanom drvetu: pregled
Izvod
U Europi je drvo ključni građevinski materijal koji je posljednjih godina doživio porast upotrebe u građevinarstvu. Kako bi se poboljšala njegova dimenzionalna stabilnost i trajnost, toplinska modifikacija široko je prihvaćena komercijalna tehnologija. Toplinska modifikacija je popularna tehnika koja mijenja svojstva drveta, poboljšavajući njegovu otpornost na propadanje i povećavajući njegovu dimenzijsku stabilnost. Proces uključuje zagrijavanje drveta na visoke temperature u kontroliranim uvjetima, što dovodi do hemijskih reakcija koje rezultiraju raznim fizičkim i mehaničkim promjenama. U ovom će se radu raspravljati o učincima toplinske modifikacije na fizikalna svojstva drveta, kao što su gustoća, sadržaj vlage i boja, kao i njezin utjecaj na mehanička svojstva, uključujući čvrstoću, krutost i tvrdoću. Dodatno, pregled će ispitati faktore koji utječu na stepen modifikacije, kao što su temperatura, trajanje i vrsta drveta. Na kraju, rad će zaključiti pregledom trenutnog stanja istraživanja u ovom području i identificirati potencijalne puteve za buduća istraživanja.
Ključne reči: Drvo, gubitak mase, modul elastičnosti, gradnja, komercijalna, tehnologija.
Abdlmanam S. A. Elmaryami1*, Amal A. E. Mohamed2
1The Bright Star University [BSU], El-Brega, Libya,
2University of Tobruk, Tobruk, Libya
Scientificpaper
ISSN 0351-9465, E-ISSN 2466-2585
https://doi.org/10.5937/zasmat2303327E
Zastita Materijala 64 (3)
327 – 339 (2023)
A Novel 2-D mathematical modeling to determine LHP to protectthe industrial transient heat treatment quenched low carbon steels bar
Abstract
2-dimensional mathematical model of axisymmetric transient industrial quenched low carbon steel bar, to examine the influence of process history on metallurgical and material characteristics, a water-cooled model based on the finite element technique was adopted. A 2-dimensional axisymmetric mathematical model was utilized to predict temperature history and, as a result, the hardness of the quenched steel bar at any node (point). The LHP (lowest hardness point) is evaluated. In this paper, specimen points hardness was evaluated by the transformation of determined characteristic cooling time for phase conversion t8/5 to hardness. The model can be used as a guideline to design cooling approach to attain the desired microstructure and mechanical properties, for example, hardness. The mathematical model was verified and validated by comparing its hardness results to the results of commercial finite element software. The comparison demonstrates that the proposed model is reliable.
Keywords: Heat treatment; quenching; axisymmetric steel bar; finite element; 2-D mathematical modelling ; unsteady state heat transfer.
Novo 2-d matematičko modeliranje za određivanje lhp za zaštitu industrijskog prolaznog toplotnog tretmana kaljeni niskougljenični čelici bar
Izvod
2-dimenzionalni matematički model osovine simetrične tranzijentne industrijske šipke od niskougljeničnog čelika, da bi se ispitao uticaj istorije procesa na metalurške i karakteristike materijala, usvojen je vodeno hlađeni model zasnovan na tehnici konačnih elemenata. Dvodimenzionalni osnosimetrični matematički model je korišćen za predviđanje istorije temperature i, kao rezultat, tvrdoće kaljene čelične šipke u bilo kom čvoru (tački).Ocenjuje se LHP (najniža tačka tvrdoće). U ovom radu, tvrdoća tačaka uzorka je procenjena transformacijom utvrđenog karakterističnog vremena hlađenja za faznu konverziju t8/5 u tvrdoću. Model se može koristiti kao smernica za dizajniranje pristupa hlađenju da bi se postigla željena mikrostruktura i mehanička svojstva, na primer, tvrdoća. Matematički model je verifikovan i validiran upoređivanjem njegovih rezultata tvrdoće sa rezultatima komercijalnog softvera konačnih elemenata. Poređenje pokazuje da je predloženi model pouzdan.
Ključne reči: toplotna obrada, gašenje, ososimetrična čelična šipka, konačni elementi, 2-D matematičko modeliranje, prenos toplote u nestabilnom stanju.
Thangaiyan Santhi1, Arjunan Krishnaveni2, David Selvaraj Gnanasangeetha3, Janani Kuppusamy4, Sevvanthi Kuttipaiyan4, Kaniya Duraisamy4, Thulasi Elumalai4, Sarmina Duraisamy4, Dorothy Rajendran5, Thanappan Sasilatha5, Susai Rajendran*6,7
1PG Department of Chemistry, Arasu College of Arts and Science for Women, Karur – 639 006. India, 2PG Department of Chemistry, Yadava College, Thiruppalai, Madurai, India,3Department of Chemistry, PSNA College of Engineering and Technology, Dindigul (Autonomous) India, 4PG Department of Chemistry,Namakkal Kavignar Ramaligam Government Arts College for Women, Namakkal, Tamil Nadu, India, 5Department of EEE, AMET University, Chennai, India, 6Corrosion Research Centre, Department of Chemistry, St. Antony’s College of Arts and Sciences for Women Thamaraipady, Dindigul–624005, Tamil Nadu, India,7 Pondicherry University, Puducherry, India
Scientificpaper
ISSN 0351-9465, E-ISSN 2466-2585
https://doi.org/10.5937/zasmat2303340S
Zastita Materijala 64 (3)
340 – 350 (2023)
Influence of an emulsion coating on the corrosion resistance of hull plates made of mild steel in natural sea water
Abstract
The corrosion resistance of mild steel, used to make hull plates in ship technology, in sea water before paint coating [Nippon paint SUMO XTRA durable exterior emulsion coating (emulsion coating)] and after paint coating has been measured by electrochemical studies such as polarisation study and AC impedance spectra. It is observed that after paint coating, the corrosion resistance of mild steel hull plates increases. Polarization study reveals that after paint coating, the linear polarization resistance increases and corrosion current decrease. AC impedance spectra reveal that in the presence of paint coating charge transfer resistance value increases, impedance value increases, phase angle increases and double layer capacitance value decreases. The corrosion inhibition efficiency was greater than 99%. The hull plates made of mild steel may be coated with durable exterior emulsion coating (emulsion coating). This will control the corrosion of the hull plates in the sea water. There will be increase in the life time of the hull plates.
Keywords: emulsion coating, corrosion resistance, hull plates, mild steel, natural sea water, electrochemical studies.
Uticaj emulzionog premaza na otpornost na koroziju ploča trupa od mekog čelika u prirodnoj morskoj vodi
Izvod
Otpornost na koroziju mekog čelika, koji se koristi za izradu ploča trupa u brodskoj tehnologiji, u morskoj vodi pre nanošenja boje [Nippon boja SUMO KSTRA izdržljivi spoljašnji emulzioni premaz (emulzioni premaz)] i nakon nanošenja boje je izmerena elektrohemijskim studijama kao što je studija polarizacije i spektri impedanse naizmenične struje. Primećeno je da se nakon nanošenja boje povećava otpornost na koroziju ploča trupa od mekog čelika. Studija polarizacije otkriva da se nakon nanošenja boje raste otpor linearne polarizacije i smanjuje struja korozije. Spektri impedanse naizmenične struje otkrivaju da se u prisustvu bojenog premaza vrednost otpora prenosa naelektrisanja povećava, vrednost impedanse povećava, fazni ugao raste i vrednost dvoslojnog kapacitivnosti opada. Efikasnost inhibicije korozije bila je veća od 99%. Ploče trupa od mekog čelika mogu biti premazane izdržljivim spoljašnjim emulzionim premazom (emulzioni premaz). Ovo će kontrolisati koroziju ploča trupa u morskoj vodi. Doći će do povećanja veka trajanja ploča trupa.
Ključne reči: emulzioni premaz, otpornost na koroziju, ploče trupa, meki čelik, prirodna morska voda, elektrohemijska ispitivanja.
