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1

Environmentally hazard and toxic exoskeletons of marine crustaceans wastes in synthesizing N-deacetylated chitin

El-Mekawy Rasha E.

Polimery

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2022

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Vol. 67, nr 10

503--508

EN

High molecular weight chitosan was synthesized from shrimp shells. Chemical structure of chitosan was confirmed using FT-IR, XRD, TGA, and SEM analyses. Physicochemical properties of chitosan such as molecular weight (800 000 g/mol), deacetylation degree (80%), ash content (1%) indicating effectiveness of demineralization step in removing minerals, water binding capacity (4220%), and fat binding capacity (537%), were determined. FT-IR spectra exhibited characteristic joint band at 3365 cm-1 due to –OH and –NH2 regarding to the conversion of chitin acetyl group to NH2 of chitosan.

PL

Z muszli krewetek zsyntetyzowano chitozan o wysokiej masie cząsteczkowej. Strukturę chemiczną chitozanu potwierdzono metodami FT-IR, XRD, TGA i SEM. Określono właściwości fizykochemiczne chitozanu takie jak masa cząsteczkowa (800 000 g/mol), stopień deacetylacji (80%), wskazu jącą na skuteczność procesu demineralizacji zawartość popiołów (1%), zdolność wiązania wody (4220%) i zdolność wiązania tłuszczu (537%). Widma FT-IR wykazały charakterystyczne pasmo przy liczbie falowej 3365 cm-1, pochodzące od grup –OH i–NH2, wynikające z przekształcenia grupy acetylowej chityny w NH2 chitozanu.

2

The modern approach to manufacturing of carbon-rhenium nanocomposites

Dobrzańska-Danikiewicz A. D., Wolany W.

Journal of Achievements in Materials and Manufacturing Engineering

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2022

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Vol. 115, nr 2

57--63

EN

Purpose: The aim of the paper is to present the high-temperature method of producing MWCNTs-Re nanocomposites, the selection of satisfactory production conditions and the presentation of the results of microscopic and spectroscopic studies of nanocomposites produced by this method. Design/methodology/approach: Two methods of manufacturing carbon-rhenium nanocomposites were tested: ineffective chemical synthesis and high-temperature reduction using H2, which was proven successful and allowed the production of nanocomposites with the expected properties. The received nanocomposites were investigated using Transmission Electron Microscope (TEM), and Scanning Electron Microscope (SEM), as well as were subjected to spectroscopic examination. Findings: The article presents three steps of MWCNTs-Re nanocomposites fabrication using the high-temperature method, functionalization, impregnation and reduction. As part of own work, satisfactory conditions for producing those nanocomposites using a materials science and heuristic analysis were selected. Research limitations/implications: The proposed high-temperature method allows to join rhenium nanoparticles with MWCNTs permanently. It is reasonable to test in the future whether the method is also effective for other carbon nanomaterials and/or nanoparticles of other metals. Practical implications: MWCNTs-Re nanocomposites can be used as sensors of gases that are harmful to the environment. It was also confirmed that the MWCNTs-Re_4 nanocomposite has catalytic properties. Originality/value: The paper presents a modern approach to the manufacturing of MWCNTs-Re nanocomposites, which assumes the use of a high-temperature furnace to heat the material in a hydrogen atmosphere.

3

Biological synthesis and characterization of titanium dioxide nanoparticle from Cynodon dactylon

Renitta R. E., Jebaseeli T. J., Dhanaraj A., Paul S.

Journal of Achievements in Materials and Manufacturing Engineering

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2022

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Vol. 113, nr 1

31--41

EN

Purpose: There are several advantages of using a biological technique to produce nanoparticles versus a chemical method. The primary goal of this work is to characterize and biologically synthesize titanium dioxide (TiO2) nanoparticles from Cynodon dactylon. The characterization has experimented with UV-Vis Spectroscopy, EDX analysis, SEM, XRD, and FTIR. Design/methodology/approach: The suggested study uses a simple biological technique to accomplish the systematic biological synthesis of TiO2 nanoparticles utilizing Cynodon dactylon plant extract and titanium tetra isopropoxide as a precursor. UV-Vis spectroscopy, Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and X-Ray Diffraction (XRD) are used to confirm the fabrication of the TiO2 nanoparticles. The plant extract as well as titanium-based nanoparticles of the herb, Cynodon dactylon will be tested for its antibacterial activity against human pathogens. This eco-friendly technique for nanoparticle synthesis is straightforward and adaptable to major commercial manufacturing and technological applications. Findings: Cynodon dactylon biosynthesis of TiO2 nanoparticles is efficient, nutrition dependent, does not employ hazardous compounds, and happens at neutral pH levels. The antibacterial study results show that TiO2 nanoparticles synthesized using Cynodon dactylon have good antibacterial properties. TiO2 nanoparticle method of action against bacteria is unknown. This is an alternative process for synthesising TiO2 nanoparticles, apart from other chemical protocols, since this is quick and non-toxic. The antimicrobial property of biologically synthesized TiO2 nanoparticles against Escherichia coli, Staphylococcus aureus, and Acinetobacter baumannii was tested at four different doses of 15 μl/mg, 25 μl/mg, 50 μl/mg, and 75 μl/mg. The present results revealed the 75 μl/mg concentration got the highest zone of inhibition (15, 13, 15 mm) for Acinetobacter baumannii, Staphylococcus aureus, and Escherichia coli. Research limitations/implications: Many nanoparticles smaller than 100 nm are firmly agglomerated with each other in the study. TiO2 nanoparticles absorb in the UV region of 200 to 400 nm. XRD measurements confirmed the presence of TiO2 nanoparticles in the biologically produced sample. In our work, EDX was used to confirm the existence of Ti after its synthesis by Cynodon dactylon. Practical implications: The biosynthesized TiO2 nanoparticles utilizing Cynodon dactylon plant extracts exhibit a good potent antibacterial activity. The proposed results showed that the TiO2 nanoparticles are well suited for biomedical applications. Originality/value: The suggested research identifies several eco-friendly, biological, and cost-effective procedures for manufacturing nano-coated herbal products. The agar well diffusion technique was used to assess antibacterial activities toward test pathogens such as Acinetobacter baumannii, Staphylococcus aureus, and Escherichia coli.

4

Charakteryzacja morfologii powierzchni warstwy fotoanody oraz warstwy kropek kwantowych na podłożu porowatym w ogniwach fotowoltaicznych III generacji

Kwaśnicki Paweł, Grąz Katarzyna, Gronba-Chyła Anna

Inżynieria Materiałowa

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2022

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Vol. 43, nr 3

9--13

PL

W pracy przedstawiono wyniki badań mających na celu określenie stopnia upakowania struktur niskowymiarowych w postaci kropek kwantowych (QDs) dla podłoży mezoporowatych. Wykorzystanie kropek kwantowych w fotowoltaice pozwala na poprawę efektywności konwersji oraz poszerzenie spektrum absorpcyjnego. Wyzwaniem technologicznym jest zarówno proces depozycji QDs, jak i znalezienie odpowiedniej metody określenia kluczowych parametrów, w tym stopnia upakowania, jednorodności rozmieszczenia QDs czy ich parametrów przestrzennych. W pracy przedstawiono wyniki badań z wykorzystaniem skaningowej mikroskopii elektronowej oraz pomiarów przy użyciu spektroskopii Ramana.

EN

This paper presents the results of a study to determine the packing of low-dimensional structures in the form of quantum dots (QDs) for mesoporous substrates. The use of quantum dots in photovoltaics allows for improved conversion efficiency and broadening of the absorption spectrum. The technological challenge is both the deposition process of the QDs and finding a suitable method to determine key parameters including the degree of packing, homogeneity of QDs distribution or their spatial parameters. In this paper, results from scanning electron microscopy and measurements using Raman spectroscopy are presented.

5

Scanning Electron Microscopy as a Tool for Castings Quality Analysis

Jezierski Jan, Dojka M., Stawarz M., Dojka R.

Archives of Foundry Engineering

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2022

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Vol. 22, iss. 1

53--61

EN

Nowadays, the best castings’ manufacturers have to meet very demanding requirements and specifications applicable to mechanical properties and other characteristics. To fulfill those requirements, more and more sophisticated methods are being used to analyze the internal quality of castings. In many cases, the commonly used Non-Destructive Methods, like X-ray or ultrasonic testing, are not enough to ensure precise and unequivocal evaluation. Especially, when the properties of the casting only slightly fail the specification and the reasons for such failures are very subtle, thus difficult to find without the modern techniques. The paper presents some aspects of such an approach with the use of Scanning Electron Microscopy (SEM) to analyze internal defects that can critically decrease the performance of castings. The paper presents the so-called bifilm defects in ductile and chromium cast iron, near-surface corrosion caused by sulfur, micro-shrinkage located under the risers, lustrous carbon precipitates, and other microstructure features. The method used to find them, the results of their analysis, and the possible causes of the defects are presented. The conclusions prove the SEM is now a powerful tool not only for scientists but it is more and more often present in the R&D departments of the foundries.

6

Działanie czynników mechanicznych oraz termicznych na morfologię włosów ludzkich i zwierzęcych

Dobosz Magda, Kalska-Szostko Beata

Wiadomości Chemiczne

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2021

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[Z] 75, 5-6

823--844

EN

The main purpose of the presented study was to investigate and compare the influence of mechanical and thermal factors on the morphology of human and animal hair. Several factors that may occur during criminal offenses were selected for testing including cutting by a scalpel or scissors, damaging by a hammer; and high, or low-temperature thermal treatment (heating for 1h, or 24 hours at elevated temperatures 100°C, 200°C, and 300°C, as well as freezing for 24 hours at -20°C, or for 10 minutes in liquid nitrogen (-197°C)). The impact of selected mechanical and temperature factors on human and animal hair was made mainly on the basis of Scanning Electron Microscopy (SEM). Moreover, the elemental composition of the hair was investigated and analyzed using an EDX (Energy - Dispersive X-ray) spectrometry. Performed tests show the degree of human hair degradation depending on the examined factor and time.

7

Correlation of manufacturing defects and impact behaviors of kenaf fiber reinforced hybrid fiberglass/Kevlar polyester composite

Suriani M. J., Sapuan S. M., Ruzaidi C. M., Naveen J., Syukriyah H., Ziefarina M.

Polimery

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2021

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T. 66, nr 1

30--35

PL

Zbadano udarność hybrydowego kompozytu polimerowego na osnowie żywicy poliestrowej napełnionej włóknami szklanymi i kevlarowymi wzmocnionego włóknem łykowym kenaf. Wytworzono pięć próbek różniących się zawartością włókien kenafu (0, 15, 45, 60 i75% obj.) Próbkę kontrolną stanowił kompozyt z 0% obj. udziałem włókien kenaf (0%). Wykazano, że hybrydyzacja wpłynęła na poprawę właściwości udarowych wyjściowego kompozytu. Wyniki potwierdzono analizą SEM defektów produkcyjnych otrzymanego kompozytu. Stwierdzono, że zachodzi korelacja między wytrzymałością na uderzenie awadami produkcyjnymi badanego hybrydowego kompozytu poliestrowego wzmocnionego włóknami kenaf. Powstałe podczas produkcji wady produkcyjne wistotnym stopniu pogarszają właściwości udarowe kompozytów.

EN

In this study, the impact properties of kenaf fibre reinforced hybrid fiberglass/Kevlar polymeric composite was investigated. In this study, a new fiber arrangement based on kenaf bast fiber as reinforcement to the hybrid fiberglass/Kevlar fiber and polyester as matrix used to fabricate the hybrid polymeric composite. Five different types of samples with different of kenaf fiber content based on volume fraction (0, 15, 45, 60 and 75%) to hybrid fiberglass/Kevlar polymer composites were manufactured. 0% of kenaf fiber has been used as control sample. The results showed that hybridization has improved the impact properties. These results were further supported through SEM micrograph of the manufacturing defects of the polymer composite. Based on literature work, manufacturing defects that occurs in composite system reduced the mechanical properties of the material. Therefore, in this research the correlation of impact behaviors and manufacturing defects of kenaf fiber reinforced hybrid fiberglass/Kevlar polymeric composite has been successfully done. As conclusion, the highest manufacturing defects determined in the composites during the fabrication significantly lowest the results of impact behavior.

8

Understanding technical cleanliness: importance, assessment, maintenance

Faber Joanna, Brodzik Krzysztof, Nycz Marta

Combustion Engines

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2021

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R. 60, nr 3

41--50

EN

Development of the automotive industry, including so-called dowsizing and rightsizing, entails the need to ensure, and hence to verify, the stringent cleanliness levels of an increasing number of car components. The assurance of proper cleanliness level requires knowledge of the entire production process and precise information on the contaminants that will allow to identify their sources. Obtaining reliable cleanliness information requires establishing of many different factors, i. a. selection of proper contamination extraction and collection technique, proper parameters of extraction, validation of extraction procedure, methods of particles analysis. Analytical techniques which are implemented include gravimetric, optical microscopy and advanced techniques like scanning electron microscopy. This work present’s actual state of knowledge regarding technical cleanliness analysis of components. Important aspects of QA&QC in technical cleanliness assessment are also discussed.

9

Fabrication and characterization of Zr microplasma sprayed coatings for medical applications

Voinarovych Sergii G., Alontseva Darya L., Kyslytsia Oleksandr N., Kaliuzhnyi Sergii, Khozhanov Alexandr R., Krasavin Alexander, Kolesnikova Tatiana

Advances in Materials Science

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2021

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Vol. 21, nr 2(68)

93--105

EN

This paper presents new results of studying the influence of parameters of microplasma spraying (MPS) of Zr wire on the structure of Zr coatings. The coating experiments were accomplished in a two level fractional factorial design. Individual particles of sprayed Zr wire and their splats on the substrate were collected under various spraying parameters (amperage, spraying distance, plasma gas flow rate and wire flow rate) and evaluated by Scanning Electron Microscopy (SEM) to establish the effect of particle size and shape on the coating microstructure. The particles were characterized by measurement of their sizes and the obtained results were evaluated in terms of their degree of melting. This was compared with the experimentally observed coating microstructure type and finally correlated to the investigated coating porosity to select the specific MPS parameters of Zr coatings depositing onto medical implants from Ti alloy. It was found that the main parameters influencing the size of the sprayed Zr particles and the porosity of the Zr coatings are the plasma gas flow rate and amperage. It was demonstrated that it is possible to control the porosity of Zr microplasma coatings in the range from 2.8% to 20.3% by changing the parameters of the MPS. The parameters of microplasma spraying of Zr wire were established to obtain medical implant coatings with porosity up to 20.3% and pore size up to 300 μm.

10

Wpływ czynników chemicznych na strukturę i budowę włosów ludzkich

Dobosz Magda, Kalska-Szostko Beata

Wiadomości Chemiczne

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2020

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[Z] 74, 7-8

453--476

EN

The main purpose of the presented study was to investigate the influence of chemical factors on the morphology of human hair. Few factors that may occurduring criminal offenses were selected for testing, including aqueous solutions of hydrochloric acid (HCl), sodium hydroxide (NaOH), lead(II) nitrate (Pb(NO3)2), cadmium(II) nitrate (Cd(NO3)2), sodium chloride (NaCl), ethanol (C2H5OH), water (H2O). The description of the effects of chosen chemical compounds on hair was made mainly on the basis of Scanning Electron Microscopy (SEM). In addition, the elemental composition of the hair as an effect of interaction with solution was examined and analyzed using an EDX (Energy - Dispersive X-ray) spectrometry. Performed tests show the degree of human hair degradation and contamination depending on the examined factor and time.

11

Metody mikroskopowe w ocenie procesów wykończania wyrobów włókienniczych

Machnowski Waldemar, Wrzosek Henryk

Technologia i Jakość Wyrobów

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2020

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R. 65

4--20

PL

Badanie wyrobów włókienniczych odgrywa istotną rolę w systemie zapewnienia jakości tekstyliów, a także w pracach nad rozwojem nowych technologii i produktów włókienniczych. Istnieje wiele metod oceny struktury i właściwości włókien i wyrobów włókienniczych. Bardzo ważne miejsce wśród tych metod zajmują techniki mikroskopowe, w szczególności mikroskopia optyczna i skaningowa mikroskopia elektronowa (SEM). W artykule podano krótki przegląd możliwych zastosowań metod mikroskopowych do analizy efektów niektórych operacji wytwarzania tekstyliów. Wykorzystanie mikroskopu optycznego umożliwiło identyfikację przyczyn powodujących nierównomierność barwy wyrobów bawełnianych. Z przeglądu literatury oraz doświadczeń własnych autorów wynika, że metody mikroskopowe stanowią cenne narzędzie w badaniu włókien i wyrobów włókienniczych.

EN

Fabric testing plays an important role in the quality assurance system and in the development of new textile technologies and products. There are many test methods used to evaluate the structure and properties of fibers and textile materials. Among these methods, microscopic techniques – especially optical microscopy and scanning electron microscopy (SEM) – are one of the most important methods. This paper provides a brief overview of the possible uses the microscopic methods for determining the results of some textile manufacturing processes. A review of the literature and the authors experiences in this field indicate that microscopic methods are a valuable tool for the testing and assessing the performance of fibers and textile products.

12

Characterisation of Mg-Zn-Ca-Y powders manufactured by mechanical milling

Lesz S., Tański T., Hrapkowicz B., Karolus M., Popis J., Wiechniak K.

Journal of Achievements in Materials and Manufacturing Engineering

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2020

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Vol. 103, nr 2

49--59

EN

Purpose: This paper explains mechanical synthesis which uses powders or material chunks in order to obtain phases and alloys. It is based on an example of magnesium powders with various additives, such as zinc, calcium and yttrium. Design/methodology/approach: The following experimental techniques were used: X-ray diffraction (XRD) method, scanning electron microscopy (SEM), determining particle size distributions with laser measuring, Vickers microhardness. Findings: The particle-size of a powder and microhardness value depend on the milling time. Research limitations/implications: Magnesium gained its largest application area by creating alloys in combination with other elements. Magnesium alloys used in various industry contain various elements e.g. rare-earth elements (REE). Magnesium alloys are generally made by casting processes. Consequently, the search for new methods of obtaining materials such as mechanical alloying (MA) offers new opportunities. The MA allows for the production of materials with completely new physico-chemical properties. Originality/value: Thanks to powder engineering it is possible to manufacture materials with specific chemical composition. These materials are characterized by very high purity, specified porosity, fine-grain structure, complicated designs. These are impossible to obtain with traditional methods. Moreover it is possible to refine the process even further minimalizing the need for finishing or machining, making the material losses very small or negligible. Furthermore material manufactured in such a way can be thermally or chemically processed without any problems.

13

A study on alkali resistant glass fibre concrete and its exposure to elevated temperatures

Hussain S., Yadav J. S.

Journal of Achievements in Materials and Manufacturing Engineering

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2020

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Vol. 103, nr 1

5--15

EN

Purpose: Cement concrete is characterized as brittle in nature, the loading capacity of which is completely lost once failure is initiated. This characteristic, which limits the application of the material, can in one way be overcome by the addition of some small amount of short randomly distributed fibers (steel, glass, synthetic). Design/methodology/approach: The present study deals with the inclusion of alkali resistant glass fibers in concrete by percentage weight of cement. The mechanical properties such as compressive strength and split tensile strength have been studied after exposing the concrete samples to elevated temperatures of up to 500°C. Water binder ratios of 0.4, 0.45, 0.5, 0.55 and 0.6 have been used to prepare design mix proportions of concrete to achieve a characteristic strength of 30 MPa. The depth of carbonation post elevated temperature exposure has been measured by subjecting the concrete samples to an accelerated carbonation (5%) condition in a controlled chamber. Findings: Conclusions have been drawn in accordance to the effect of fiber replacement and temperature increment. The concrete mixes with fiber content of 1% by weight of cement had shown better strength in compression and tension compared to the other dosages and conventional concrete (without fiber). Microcracking due to internal stream pressure reduced the mechanical strengths of concrete at elevated temperatures. Also, from TGA it was observed that the amount of calcium carbonate in samples with fiber added, post carbonation was less than the mixes without fiber in it. Research limitations/implications: The present study has been limited to alkali resistant glass fibers as the conventional glass fibers undergo corrosion due to hydration. Practical implications: The glass fiber reinforced concrete can be used in the building renovation works, water and drainage works, b ridge and tunnel lining panels etc. Originality/value: Based upon the available literature, very seldom the studies are addressing the behaviour of alkali resistant glass fiber concrete and its exposure to elevated temperatures.

14

Study of Nonmetallic Inclusions in Aluminum–Silicon Alloys

Galek Tomasz, Łączek Andrzej, Łysiak Karol

Advances in Manufacturing Science and Technology

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2020

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Vol. 44, nr 1

28-31

EN

In this article, a study of nonmetallic inclusions introduced during the casting process of the aluminum–silicon alloy is presented. The samples were investigated using a scanning electron microscope to find the chemical composition and X-ray tomography to check the volumetric content of the non-metallic inclusions. The samples were made from AlSi7Mg alloy, used for car wheels, with 7% weight content of Si, 89% of Al, and 0.3% of Mg. The main goal of our investigations was to find out the chemical composition of the impurities and to identify the stage of the casting process at which the impurities are introduced.

15

Zastosowanie skaningowej mikroskopii elektronowej w badaniach materiałów inżynierskich

Boryło Paulina, Sozańska-Jędrasik Liwia, Gołombek Klaudiusz

LAB Laboratoria, Aparatura, Badania

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2019

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R. 24, nr 2

6--13

16

Metody badawcze cienkich warstw wytworzonych metodą osadzania warstw atomowych

Boryło Paulina, Szindler Marek, Szindler Magdalena, Lukaszkowicz Krzysztof

LAB Laboratoria, Aparatura, Badania

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2019

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R. 24, nr 5

16--18

17

Nanoporous surface treatment of aluminium by anodisation in oxalic acid

Dass G., Kushwaha M. K.

Journal of Achievements in Materials and Manufacturing Engineering

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2019

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Vol. 93, nr 1-2

20--25

EN

Purpose: Well-ordered nanoporous anodic surface on aluminium substrate was obtained by anodisation method in 0.3 M of oxalic acid as an electrolyte. The objective of this perusal is to describe a system for the magnifying diameter of pores and resistance of demolition of the oxide layer at various voltages. The effect of voltage and time of anodisation process in which obtaining the required structure in AAO film. Design/methodology/approach: The experiments have been performed on a setup for anodisation considering variables parameters. In this study, AAO Templates were prepared in oxalic acid of 0.3 M concentration under the potential range of anodisation 30-40 V at relatively temperatures range from 20-30°C of an electrolyte. Anodic voltage, current density and temperature of electrolyte were adopted as electrical parameters during anodisation. Before anodisation starts two crucial pre-treatment i.e. annealing and electropolishing are finished. Findings: The diameter of pores and pitch of pores are well-proportional to anodisation voltage and process time. The pore diameters were 85 nm, 138 nm, 184 nm, 248 nm with having 9, 16, 27, 37 porosity % respectively. The thickness of AAO film in all cases has been found to be maximum or constant after one hour in second step anodisation. The anodisation parameters like voltage, the time duration of the anodisation process and temperature are very essential features which influencing the fabrication of an AAO film. Research limitations/implications: The anodisation process is very easy to perform but very complex to understand as there are many parameters which may affect it. Practical implications: After that, the second step anodisation for the next half hour, there will be no change in the thickness of AAO film but after that dissolution rate starts over the formation rate and finally thickness will be decreasing. Originality/value: Therein is numerous macropores in the membrane with the size of pores variation from 163 to 248 nm. The diameter of pores, thickness, and pore density of AAO film was determined through Scanning Electron Microscopy (SEM), which exhibited that homogeneous honeycomb-like structure has appeared on the entire surface where anodisation performed precisely.

18

Wykorzystanie technik analitycznych do oceny emisji lotnych związków organicznych uwalnianych z materiałów polimerowych, jako obiecujące rozwiązania w kontroli ich jakości. Cz. 1

Marć Mariusz, Namieśnik Jacek, Haponiuk Józef, Formela Krzysztof

Analityka : nauka i praktyka

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2019

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nr 2

47--51

PL

W celu uzyskania danych na temat charakterystyki morfologicznej i właściwości fizykochemicznych danego przedmiotu wykonanego z tworzyw sztucznych (lub gumy) powszechnie wykorzystywane są takie techniki, jak: spektroskopia w podczerwieni, różnicowa kalorymetria skaningowa, analiza termograwimetryczna, analiza dynamicznych właściwości mechanicznych, chromatografia żelowa czy skaningowa mikroskopia elektronowa.

19

Analysis of Fly Ash Concrete With Scanning Electron Microscopy and X-Ray Diffraction

Uzbaş Burhan, Aydın Abdulkadir Cüneyt

Advances in Science and Technology. Research Journal

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2019

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Vol. 13, no 4

100--110

EN

In this study, the effects of using different ratios of fly ash on hydration products as well as the mechanical and microstructural properties of hardened concrete were investigated. Portland cement was replaced with 5%, 10%, 15% and 20% fly ash (FA) by weight. The microstructural properties of the obtained samples were investigated by means of X-ray diffraction (XRD) and Scanning electron microscopy (SEM). Fly ash has negative effect on 7 days concrete strength; however, it was seen that fly ash increases the compressive strength of 28 and 90 days concrete. The XRD analysis showed that the ratio of calcium hydroxide (CH), which is produced by hydration, decreases depending on the concrete age and the amount of fly ash. The SEM analysis showed that the usage of fly ash decreases gaps and increases C-S-H which is also a hydration production. When Portland cement was replaced with 10% fly ash by weight, compressive strength has increased and microstructure of concrete has improved. The reason for this is filling of gaps by fly ash and the decrease in the amount of Ca(OH)2 due to the reaction between fly ash and Ca(OH)2. Within this scope, the development in microstructure of fly ash concrete was evaluated in 90 days duration and a change of the development with compressive strength was investigated.

20

Analysis of the electrolytically polished skeletal dentures surfaces using various nano- and microscopic technologies

Dąbrowa Tomasz, Majstrzyk Wojciech, Tamulewicz Magdalena, Piasecki Tomasz, Kunicki Piotr, Więckiewicz Włodzimierz, Gotszalk Teodor

Acta of Bioengineering and Biomechanics

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2019

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Vol. 21, no. 4

123--129

EN

The surface roughness of the dental restorations is significant to the denture plaque adhesion. Methods: In this work, we present the complex analysis of the electropolished CoCrW alloy remanium® star (Dentaurum, Germany) samples with laserengraved fiducial marks performed using complementary set of micro- and nanoscopic techniques: optical profilometry (OP), atomic force microscopy (AFM), scanning electron microscopy (SEM) and focused ion beam (FIB) milling. Results: Both mean and RMS roughness of the samples were reduced by electopolishing process, however, the results obtained using OP and AFM exhibited some discrepancies. This was caused by the relatively high local protruding defects developed on the processed surface. The cross-sections of the protrusions were made to analyze the cause of their formation as the EDS elemental content maps revealed that their composition was uniform. We also analyzed the local roughness in the smaller areas free from the defects. Conclusions: In that case, both OP and AFM techniques delivered the same results. Analysis of results showed that various methods used for the surface roughness evaluation have to be used simultaneously to obtain complete and true analysis of the technological CoCrW samples.