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Tribological Properties of Graphene Oxide-Metal-Carbon Composites

Muzyka R., Duda P., Robak Z., Kaptacz S., Drewniak S.

Tribologia

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2018

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nr 5

53--64

EN

Cu-C composites are materials used for the production of brushes, contacts, and pressing shoes for electric machines due to their mechanical and wear properties. These characteristics include good thermal and electrical conductivity, a low coefficient of friction, and lubricity under varying operating conditions. Currently, graphite and copper nanopowder based materials are used as a metal-carbon material in different ratios of these components. Graphite content in this kind of material has a positive effect on the smaller consumption of, e.g., rings and commutators. In contrast, a material without graphite content is used at high current densities. The examples of such machines are a DC motor starter or generators for electrolysis characterized by large current and low voltage. The present study tested the effect of graphene oxide (rGO) content on tribological properties in contact with steel in Cu-C composites. Tests were conducted on a ball-on-disk apparatus in conditions of dry friction. Disk wear and surface geometrical structure parameters (SGP) of the samples after tribological tests were determined on the basis of measurements made on the Talysurf.3D contact profilometer from Taylor Hobson. Damage mechanisms were identified and their relationships with structural characteristics were deducted. The hardness of Cu-C materials was higher than in copper. Cu-C based materials produce a better improvement of wear resistance, while the wear resistance of the graphene oxide based composites also decreased.

PL

Kompozyty Cu-C są materiałami używanymi do produkcji szczotek, styków i ślizgów do maszyn elektrycznych ze względu na ich dobre właściwości mechaniczne i odporność na zużycie. Cechy te obejmują dobre przewodnictwo cieplne i elektryczne, niski współczynnik tarcia i samosmarność w różnych warunkach roboczych. Obecnie grafit i nanoproszek na bazie miedzi są stosowane jako materiały kompozytowe metal–węgiel w różnych proporcjach. Obecność grafitu w tym rodzaju materiału ma pozytywny wpływ na mniejsze zużycie np. pierścienia i komutatora. Materiały bez dodatku grafitu na ogół są stosowane podczas używania dużych gęstości prądu. Przykładami takich maszyn są rozrusznik silnika prądu stałego lub generatory do elektrolizy charakteryzujące się dużym prądem i niskim napięciem. W niniejszym artykule zbadano wpływ zawartości tlenku grafenu (rGO) w kompozytach Cu-C na właściwości tribologiczne w kontakcie ze stalą. Testy przeprowadzono na urządzeniu z kula–tarcza w warunkach tarcia technicznie suchego. Zużycie tarcz i parametry struktury geometrycznej powierzchni (SGP) próbek po testach tribologicznych wyznaczono na podstawie pomiarów wykonanych na profilografometrze stykowym Talysurf 3D firmy Taylor Hobson. Zidentyfikowano mechanizmy uszkodzeń i powiązano z cechami strukturalnymi. Twardość materiałów Cu-C była wyższa niż w miedzi. Materiały na bazie Cu-C odznaczały się poprawą odporności na zużycie, podobnie jak kompozyty modyfikowane tlenkiem grafenu w porównaniu z materiałem osnowy.

2

Experimental investigation of particle size distribution and morphology of alumina-yttria-ceria-zirconia powders obtained via sol–gel route

Nakonieczny D. S., Antonowicz M., Paszenda Z. K., Radko T., Drewniak S., Bogacz W., Krawczyk C.

Biocybernetics and Biomedical Engineering

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2018

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Vol. 38, no. 3

535--543

EN

Background: Oxide-doped zirconia is currently commonly used ceramics in dental prosthetics. However, its use raises a lot of controversy. This is related to the stability of the zirconia metastable phases in the human mouth environment and it sensitivity for the so-called low-temperature degradation. A key way to avoid this type of negative phenomena is doping ZrO2 with selected metal oxide sand choosing appropriate methods for the synthesis of ceramic powders. Objective: The aim of this paper is to present investigations of modification and to analyse the influence of chemical composition and volume of parent-solvent for the morphology and thermal properties of ceramic powders prepared in a ZrO2-CeO2-Y2O3-Al2O3 system. Methods: The powders were obtained by using the sol–gel method in an inert gas atmosphere and ambient temperature using zirconium n-propoxide for this purpose. Morphology was examined by using scanning electron microscopy (SEM) and particle size distribution (PSD); thermal properties was evaluated using thermogravimetric analysis (TGA/DTA/DTG), and chemical composition was confirmed by using electron probe microanalysis (EPMA). Results: Depending from the volume of the CeO2 precursor solution of and regardless of the volume of the second oxide precursor, was observed difference in morphology of the obtained powders. Overall trend is related to reduce the size of agglomerates with an increase in the volume of the precursor of CeO2. Conclusions: The influence of various chemical compositions for morphology and thermal properties is negligible. In contrast, a clear correlation is observed between the volume of parent alcohol for both morphology and thermal properties. Use of sol–gel method to further research in view of these results appears to be appropriate.

3

Phase composition and morphology characteristics of ceria-stabilized zirconia powders obtained via sol-gel method with various pH conditions

Nakonieczny D. S., Paszenda Z. K., Basiaga M., Radko T., Drewniak S., Podwórny J., Bogacz W.

Acta of Bioengineering and Biomechanics

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2017

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Vol. 19, no. 2

21--30

EN

High purity, fine crystalline, degradation-free at low temperature powders have attracted special interest in CAD/CAM prosthetic dentistry full ceramic restorations. This study reports the preparation and characterisation of zirconia-ceria (0.9ZrO20.1CeO2) powders. Materials were obtained from zirconium-n-alkoxide and cerium nitrate hexahydrate in the pH 2–4 and 8–10. Methods: Zirconia-ceria powders were obtained with the sol-gel method in a humid-free environment. Thermal analysis (TGA/DTA) of the as-prepared materials was made for an assessment of its behaviour at elevated temperatures. Specimens were dried at 80°C and calcinated in two stages: at 300°C with soaking time 2.5 h and 850°C with holding time 2.5 h, in order to evaluate the phase transformations. Thermal analyses of the as-dried powders were made for an assessment of its thermal behaviour during heat treatment up to 1000 °C. By X-ray diffraction (XRD), polymorphs of ZrO2 were identified. Additionally, scanning electron microscopy (SEM) and laser particle size distribution (PSD) were involved for characterisation of morphology of the powders. Results: We found a correlation between the pH of the colloidal system and the morphology of the as-obtained powders. Based on analysis (SEM,PSD), structures were identified known as soft and hard agglomerates. Conclusions: In summary, it can be stated differences were found between powder morphology depending on the used pH, which can be crucial for powder densification during sintering and compacting green bodies which, as a consequence, may be crucial for the lifetime of zirconia prostheses. Correlations between phase composition and pH are difficult to grasp, and require further more sophisticated studies.

4

ZrO2-CeO2 ceramic powders obtained from a sol-gel process using acetylacetone as a chelating agent for potential application in prosthetic dentistry

Nakonieczny D., Paszenda Z., Drewniak S., Radko T., Lis M.

Acta of Bioengineering and Biomechanics

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2016

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Vol. 18, no. 3

53--60

EN

Purpose: The main objective of this study was to obtain single-phase β-ZrO2 powders with so-called soft agglomerates reproducibile morphology with acetyl-acetone as a chelating-agent. To the best of our knowledge there is no avaiable data which determine the effect of acetyl acetone on the phase composition and morphology of ceria-doped ZrO2 powders for biomedical applications. Methods: Twenty variants of powders with different water to zirconia precursor and acetylacetone to zirconia precursor molar ratios were prepared. 0.9ZrO20.1CeO2 powders were obtained by a hydrolysis and condensation and further calcination of zirconium n-propoxide in a simple one-step sol-gel process. Influence of acetyloacetone to zirconia precursor on the phase composition ratio and water to zirconia precursor was investigated. Samples have been characterized by X-ray diffraction (XRD), Raman spectroscopy (RS), thermal analysis (TGA/DTA) and scanning electron microscopy (SEM) measurements. Results: Ceramic powders prepared by sol-gel process, according to the various concentration of chelating agent and water show different morphology and phase composition. Conclusions: Higher molar ratios of AcAc in range with smaller amounts of water cause hard agglomerates, obtained powders are characterized by highly thermally stable behaviour and various phase composition. With higher molar ratios of water to zirconium-n-propoxide so-called soft agglomerates and one phase powders are obtained.

5

Metody charakteryzacji grafenu wykorzystywanego w sensorowych układach rezystancyjnych

Drewniak S., Pustelny T., Strupiński W., Pasternak I., Opilski Z.

Prace Naukowe Politechniki Śląskiej. Elektryka

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2014

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z. 2-3

63--72

PL

Zanieczyszczenie środowiska pociąga za sobą konieczność monitoringu wybranych atmosfer gazowych. W niniejszym artykule zostaną przedstawione wyniki charakteryzacji warstwy gazoczułej (grafenu) w rezystancyjnym czujniku cienkowarstwowym, pozwalającym wykrywać niskie zawartości wodoru oraz dwutlenku azotu w atmosferze powietrza syntetycznego. Zostaną przedstawione m.in. obrazy topografii powierzchni oraz widma ramanowskie struktury. Analizowane będą zmiany, jakie zachodzą w strukturze (obserwowane na widmach ramanowskich) pod wpływem jej kontaktu z atmosferą zawierającą 3% wodoru.

EN

The environmental pollution entails the monitoring of selected gas atmospheres. In this paper, the results of characterization the thin film resistance sensor (characterization of grapheme - sensitive layer) will be presented. Such sensor can detect the hydrogen and nitrogen dioxide in the atmosphere of synthetic air at a very low level. There will be presented, among others, the images of topography and raman’s spectras of the structures. There will be analyzed changes which occure in the structure (observed at the Raman’s spectra) due to its contact with the atmosphere containing 3% hydrogen.

6

The sensitivity of sensor structures with oxide graphene exposed to selected gaseous atmospheres

Pustelny T., Drewniak S., Setkiewicz M., Maciak E., Urbańczyk M., Procek M., Gut K., Opilski Z., Jagiello J., Lipinska L.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2013

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Vol. 61, nr 3

705--710

EN

The paper presents the results of investigations on the resistive structure with a graphene oxide (GO) sensing layer. The effects of dangerous gases (hydrogen and nitrogen dioxide) on the structure were studied; the resistance changes were examined during the flow of the selected gas in the atmosphere of synthetic air. Measurements were performed with a special emphasis on the detection of low concentrations of the analyzed gases. The reactions of the sensing structure to the effect of nitrogen and synthetic air at different humidity were also tested. Much attention was also paid to the fast response of the sensor to the changes in the gas atmosphere. The thin palladium layer (~2 nm) has been applied in order to improve the sensing properties of the structure. The investigations were performed in the temperature range from RT to 120°C and the analyzed gases in synthetic air were batched alternately with pure synthetic air.

7

The sensibility of resistance sensor structures with graphene to the action of selected gaseous media

Pustelny T., Setkiewicz M., Drewniak S., Maciak E., Stolarczyk A., Urbańczyk M., Procek M., Gut K., Opilski Z., Pasternak I., Strupinski W.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2013

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Vol. 61, nr 2

293--300

EN

The paper presents resistance sensor structures with a graphene sensing layer. The structures were tested concerning their sensitivity to the affects of hydrogen, nitrogen dioxide and steam in an atmosphere of a synthetic air. Investigations have proved that resistance structures with a graphene layer are sensitive to the presence of the tested gases. The resistance of the structures amounted to about 10Ω, whereas changes in the resistances affected by the external gaseous medium were contained within the range of a several mΩ. The investigations confirmed that the resistance structures with graphene exposed to the affect of hydrogen in atmosphere of synthetic air change their resistances practically at once (within the order of only a few seconds). This indicates that such structures might be practically applied in sensors of hydrogen ensuring a short time of response.

8

Gas sensors based on nanostructures of semiconductors ZnO and TiO2

Pustelny T., Procek M., Maciak E., Stolarczyk A., Drewniak S., Urbańczyk M., Setkiewicz M., Gut K., Opilski Z.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2012

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Vol. 60, nr 4

853-859

EN

The paper presents a resistance structures with sensor layers based on nanostructures elaborated on the base of TiO2 and ZnO. The structures were tested concerning their sensitivities to the effects of nitrogen dioxide in the atmosphere of synthetic air. The TiO2 and ZnO nanostructures played the role of sensor layers. Investigations have proved that the elaborated resistance structures with TiO2 and ZnO layers are sensitive to the presence of NO2 in the atmosphere of synthetic air. The resistance of the structure amounted to about 20 in the case of ZnO structures and to about 200 in the case of TiO2 structures. The investigations confirmed that resistance structures with ZnO and TiO2, exposed to the effect of nitrogen dioxide in the atmosphere of synthetic air changes their resistances relatively fast. This indicates that such structures might be practically applied in sensors of nitrogen dioxide ensuring a short time of response.

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Analiza czułości planarnych, polimerowych światłowodów rewersyjnych

Gut K., Pustelny T., Drewniak S.

Elektronika : konstrukcje, technologie, zastosowania

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2010

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Vol. 51, nr 6

27-30

PL

W niniejszej pracy zaprezentowano analizę teoretyczną światłowodów o odwróconej symetrii ze zwróceniem uwagi na możliwe zastosowanie ich jako elementy składowe czujników. Zasada odwróconej symetrii jest oparta na wytworzeniu współczynnika załamania podłoża falowodowego mniejszego niż współczynnik załamania ośrodka pokrywającego warstwę falowodową (nwody = 1,33) [5]. Taka kolejność warstw jest przeciwstawna konwencjonalnej geometrii światłowodu, gdzie podłożem jest zazwyczaj szkło ze współczynnikiem załamania ok. 1,5. Zaletą przedstawionej konfiguracji rewersyjnej jest głębsza penetracja pola zanikającego do medium pokrycia, co teoretycznie zwiększa czułość na zmiany współczynnika załamania analitu w porównaniu do tradycyjnie zaprojektowanego światłowodu [5]. W pracy prezentowane będą obliczenia czułości i badania głębokości wnikania pola zanikającego konwencjonalnego światłowodu oraz światłowodu z symetrią rewersyjną, gdzie jako współczynnik załamania warstwy światłowodowej przyjęto wartość 1,59 (polimer SU8). Polimerowe światłowody są dobrymi kandydatami do tanich i produkowanych na masową skalę modułów czujników o odwróconej symetrii.

EN

In this paper an extensive theoretical analysis of reverse symmetry waveguide was presented. Possible application this waveguides as a component of sensors was considered. Principle is based on [5] formation of the refractive index of the substaring layer which is smaller than refractive index of the (n water= 1.33). Such order of layers is opposite to conventional geometry of waveguide, where the glass with the refractive indes about 1.5 is the substrate. Deeper penetration of evanescent field to the cover medium is advantage of presented reversed configuration [5], because it increases sensitivity to the change of refractive index of the analyte comparing with traditional design waveguide. In this paper calculation of the sensitivity and the studies of depth of evanescent field conventional and reverse symmetry wayeguide will be shown. As an refractive index value 1.59 was taken (polymer SU8). Polymer waveguides are good candidates for cheap and produced on a wide scale, modules of the sensor with reverse symmetry.