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1

Wpływ piasku korundowego na właściwości betonu cementowego

Horszczaruk Elżbieta, Kiernożycki Włodzimierz

Materiały Budowlane

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2023

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nr 9

9--12

PL

W artykule przedstawiono wyniki badań wpływu odpadowego piasku korundowego używanego do piaskowania konstrukcji metalowych na właściwości betonu. Piasek korundowy zastosowano jako zamiennik 25, 50 i 75% objętości kruszywa drobnego. Przeprowadzone zostały badania konsystencji mieszanek betonowych i gęstości objętościowej betonów. Badano wytrzymałość na ściskanie i rozciąganie przy rozłupywaniu betonów po 7 i 28 dniach dojrzewania. Określono również nasiąkliwość betonów i głębokość penetracji wody pod ciśnieniem. Badania potwierdziły możliwość zastosowania piasku korundowego jako zamiennika kruszywa drobnego w betonach cementowych.

EN

The paper presents the results of research on the influence of waste corundum sand used for sandblasting metal structures on the properties concrete. Corundum sand was used as a substitute for sand in the amount of 25%, 50 and 75% of the fine aggregate volume. Tests were carried out on the consistency of concrete mixes and the bulk density of concretes. The compressive strength and tensile splitting strength were measured at the age of the concrete of 7 and 28 days. The water absorption of concretes and the depth of water penetration under pressure were also determined. The tests confirmed the possibility of using corundum sand as a substitute for fine aggregate in cement concrete.

2

Optimization of wire EDM process parameters on Al6061/Al₂O₃ composite and its surface integrity studies

Mythili T., Thanigaivelan R.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2020

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Vol. 68, nr 6

1403--1412

EN

Metal matrix composites (MMC) are finding application in many fields such as aerospace and automobile industries. This is due to their advantages such as light weight and low cost. Among all the available non-traditional machining processes, wire electric discharge machining (WEDM) is found to be a suitable method for producing complex or intricate shapes in composite materials. In this study, an aluminum metal matrix composite (AMMC) with 6% and 8% weight (wt) fraction of Al2O3 is prepared through the stir casting process. The fabricated AMMC specimen is machined using WEDM, considering various process parameters such as wt % of reinforcement, gap voltage (Vg), peak current (IP) wire tension (WT) and dielectric pressure (Pd). Output responses such as the machining rate (MR) and surface roughness (Ra) of the slots are analyzed by conducting L18 mixed orthogonal array (OA) experiments. The experiments are analyzed using techniques for order preference by similarity to ideal solution (TOPSIS) and analysis of variance (ANOVA). Based on the analyses, the optimum combination of process parameters for better MR and Ra is as follows: wt % = 6 gm, Vg = 53 V, Ip = 8 A, WT = 11 g, Pd = 13 bar. The optimum level of process parameters for MR and Ra are 1.5 mm/min and 3.648 µm, respectively. Based on ANOVA, the peak current is found to have a significant influence on MR and Ra. Moreover, based on a scanning electron microscope (SEM) image, the presence of micro-ridges, reinforcement, micro-craters, micro-cracks, recast layers and oxide formation are all analyzed on the surface being machined.

3

Thulium-doped optical fibers for fiber lasers operating at around 2 μm

Kasik I., Kamradek M., Aubrecht J., Peterka P., Podrazky O., Cajzl J., Mrazek J., Honzatko P.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2019

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Vol. 67, nr 5

981--986

EN

The paper deals with spectral and lasing characteristics of thulium-doped optical fibers fabricated by means of two doping techniques, i.e. via a conventional solution-doping method and via a nanoparticle-doping method. The difference in fabrication was the application of a suspension of aluminum oxide nanoparticles of defined size instead of a conventional chloride-containing solution. Samples of thulium-doped silica fibers having nearly identical chemical composition and wave guiding properties were fabricated. The sample fabricated by means of the nanoparticle-doping method exhibited longer lifetime, reflecting other observations and the trend already observed with the fibers doped with erbium and aluminum nanoparticles. The fiber fabricated by means of the nanoparticle-doping method exhibited a lower lasing threshold (by »20%) and higher slope efficiency (by »5% rel.). All these observed differences are not extensive and deserve more in-depth research; they may imply a positive influence of the nanoparticle approach on properties of rare-earth-doped fibers for fiber lasers.

4

Application of Nanoparticles in the Process of Phase Change Paraffin in a Chamber

Alizadeh As’ad

Advances in Science and Technology. Research Journal

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2019

|

Vol. 13, no 3

113--119

EN

In this study, melting of a phase changing material enriched with nanoparticles in a circular ring-rectangular enclosure was investigated and the results were analyzed. At the beginning of the melting process in the absence of a natural displacement, the mechanism of conduction heat transfer around the hot cylinder is the dominant mechanism. Over time, natural displacement gradually appears and deforms the melting boundary above the cylinder. Over time, when the thickness of the liquid phase grows, the thermal resistance increases, this can be verified by reviewing the Nusselt chart. So this phenomenon reduces the rate of melting and temperature changes. The results show that increasing the nanoparticle volume fraction due to increased conductivity and decreasing latent heat causes an increase in the melting rate and the amount of energy absorbed. From the study of various volume fractions, it can be concluded that the use of a higher volume fraction of 3% is more appropriate both in terms of energy and in terms of the melting rate. However, it should be taken into account that if the melting rate exceeds this value, it may cause agglomeration and deposition of nanoparticles and reducing system efficiency.

5

Abrasion Resistance of S235, S355, C45, AISI 304 and Hardox 500 Steels with Usage of Garnet, Corundum and Carborundum Abrasives

Szala Mirosław, Szafran Michał, Macek Wojciech, Marchenko Stanislav, Hejwowski Tadeusz

Advances in Science and Technology. Research Journal

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2019

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Vol. 13, no 4

151--161

EN

The steel presents a wide field of application. The abrasive wear resistance of steel relies mainly on the microstructure, hardness as well as on the abrasive material properties. Moreover, the selection of a abrasion-resistant grade of steel still seems to be a crucial and unsolved problem, especially due to the fact that the actual operating conditions can be affected by the presence of different abrasive materials. The aim of this work was to determine the effect of different abrasive grit materials i.e. garnet, corundum and carborundum on the abrasive wear result of a commonly used in industry practice steels i.e. S235, S355, C45, AISI 304 and Hardox 500. The microstructure of the steel was investigated using light optical microscopy. Moreover, hardness was measured with Vickers hardness tester. Additionally, the size and morphology of the abrasive materials were characterized. The abrasion tests were conducted with the usage of T-07 tribotester (dry sand rubber wheel). The results demonstrate that the hardness and structure of steels and hardness of abrasive grids influenced the wear results. The abrasive wear behavior of steels was dominated by microscratching and microcutting wear mechanisms. The highest mass loss was obtained for garnet, corundum, and carborundum, respectively. The usage of various abrasives results in different abrasion resistance for each tested steel grade. The AISI 304 austenitic stainless steel presents an outstanding abrasive wear resistance while usage of corundum and Hardox 500 while using a garnet as abrasive material. The C45 carbon steel was less resistant than AISI 304 for all three examined abrasives. The lowest resistance to wear in garnet and carborundum was obtained for the S235JR and S355J2 ferritic-perlitic carbon steels and in corundum for Hardox 500 which has tempered martensitic structure.

6

The Analysis of the Thermal and Dielectric Properties of High Voltage Insulating Materials with the Addition of Aluminium Oxide

Tomášková T., Trnka P., Gutten M., Korenčiak D.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 2

641--646

EN

This article describes the influence of thermal and dielectric properties of materials to properties of electrical insulating systems in high voltage electrical equipment. The aim of this experiment is to improve the thermal and dielectric properties of electrical insulating (composite) materials using micro fillers of aluminium oxide Al2O3 . Supplement of fillers of aluminium oxide with better thermal conductivity to the electrical insulating systems can be modified to increase their thermal conductivity. Improving the thermal conductivity of electric insulation by addition of micro- or nanofillers and in the same time not adversely affecting the dielectric properties is the objective of the study. Paper is presenting the results measured on prepared samples. Improved thermal conductivity is compared with other dielectric properties as: dissipation factor temperature dependences, resistivity and dielectric spectroscopy. To determine the dielectric insulating properties the following characteristics were measured: tanδ versus temperature from 110°C to 150°C, absorption and resorption currents, volume resistivity. Furthermore, this article describes analysis of moisture and conductivity the material by dielectric spectroscopy.

7

Właściwości powierzchniowe sorbentów mineralno-węglowych otrzymanych z zastosowaniem tlenku glinu jako matrycy mineralnej

Szychowski D.

Przemysł Chemiczny

|

2017

|

T. 96, nr 4

775--780

PL

Przedstawiono metodę otrzymywania sorbentów mineralno-węglowych z zastosowaniem jako surowców wyjściowych chlorku glinu i poli( alkoholu winylowego). Opracowano optymalne warunki homogenizacji matrycy mineralnej (wodorotlenku glinu) z substancją organiczną. Wykazano, że istnieje możliwość otrzymania sorbentów o właściwościach hydrofobowych i rozwiniętej strukturze porowatej, które mogą mieć zastosowanie w procesie oczyszczania ścieków przemysłowych zanieczyszczonych związkami organicznymi, co zostało wykazane we wcześniejszych pracach.

EN

Al(OH)₃ and poly(vinyl alc.) mixts. were pptd. with NH₃ from an aq. soln. of AlCl₃, carbonized at 450°C for 30 min under N₂ and studied for sp. surface by adsorption of PhH and N₂ and for structural and thermal properties, by X-ray anal. and thermal anal., resp. The composite sorbents showed sp. surface up to 253.4 m²/g and hydrophobic nature.

8

Adsorpcja jonów chromu(III) oraz jonów chromu(VI) na nanoporowatym tlenku glinu

Wojtal T.

Prace Instytutu Metalurgii Żelaza

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2017

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T. 69, nr 4

48--52

PL

Współczesne metody spektroskopowe i elektrochemiczne nie zawsze pozwalają na oznaczanie pierwiastków toksycznych takich jak chrom(VI) w bardzo niskim zakresie stężeń. Z tego powodu konieczne jest zastosowanie technik zatężania analitów. Jedną z najczęściej stosowanych technik wzbogacania jest ekstrakcja do fazy stałej. Istotne jest odpowiednie dobranie adsorbentu (fazy stałej). W pracy przebadano możliwość adsorpcji jonów chromu(III) oraz chromu(VI) na nanoporowatym tlenku glinu. Przeprowadzono odpowiednią modyfikację tlenku glinu z wykorzystaniem (3-mercaptopropyl)trimetoksysilanu (MPTMS) mającą na celu wprowadzenie grup tiolowych zdolnych do kompleksowania jonów metali. Przebadano wpływ środowiska reakcji na proces adsorpcji. Efekt modyfikacji adsorbentu weryfikowano z zastosowaniem techniki rentgenowskiej spektrometrii fluorescencyjnej z dyspersją energii (EDXRF). Pomiary stężenia jonów chromu(III) oraz jonów chromu (VI) prowadzono z wykorzystaniem emisyjnej spektrometrii atomowej ze wzbudzeniem w plazmie sprzężonej indukcyjnie (ICP OES).

EN

Modern spectroscopic and electrochemical methods do not always allow the determination of elements toxic to a very low concentration range, such as chromium (VI). Therefore, analytical concentration techniques are used, and one of the most commonly used is solid phase extraction. In this method, it is important to choose the appropriate adsorbent (solid phase). The study investigated the adsorption of chromium (III) and chromium (VI) ions on nanoporous alumina. An appropriate modification of aluminum oxide was carried out using (3-mercaptopropyl) trimethoxysilane (MPTMS) to introduce thiol groups capable of complexing metal ions. The influence of the reaction environment on the adsorption process was tested. The effect of adsorbent modification was verified using energy dispersive X-ray fluorescence (EDXRF). Measurements of chromium (III) ions and chromium (VI) ions were carried out using inductively coupled plasma optical emission spectrometry (ICP OES).

9

Characterization of Al2O3/4H-SiC and Al2O3/SiO2/4H-SiC MOS structures

Taube A., Guziewicz M., Kosiel K., Gołaszewska-Malec K., Król K., Kruszka R., Kamińska E., Piotrowska A.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2016

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Vol. 64, nr 3

537--551

EN

The paper presents the results of characterization of MOS structures with aluminum oxide layer deposited by ALD method on silicon carbide substrates. The effect of the application of thin SiO2 buffer layer on the electrical properties of the MOS structures with Al2O3 layer has been examined. Critical electric field values at the level of 7.5–8 MV/cm were obtained. The use of 5 nm thick SiO2 buffer layer caused a decrease in the leakage current of the gate by more than two decade of magnitude. Evaluated density of trap states near the conduction band of silicon carbide in Al2O3/4H-SiC MOS is about of 1×1013 eV−1cm−2. In contrast, the density of the trap states in the Al2O3/SiO2/4H-SiC structure is lower about of one decade of magnitude i.e. 1×1012 eV−1cm−2. A remarkable change in the MOS structure is also a decrease of density of electron traps located deeply in the 4H-SiC conduction band below detection limit due to using of the SiO2 buffer layer.

10

The impact of atomic layer deposition technological parameters on optical properties and morphology of Al2O3 thin films

Dobrzanski L. A., Szindler M., Szindler M., Hajduk B., Kotowicz S.

Optica Applicata

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2015

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Vol. 45, nr 4

573--583

EN

This paper presents some results of investigations on aluminum oxide Al2O3 thin films prepared by the atomic layer deposition method on polished monocrystalline silicon. It has been described how the technological parameters of the deposition process, like the number of cycles and substrate temperature, influenced the optical properties and morphology of prepared thin films. Their physical and optical properties like thickness, uniformity and refractive index have been investigated with spectroscopic ellipsometry, atomic force microscopy and UV/vis optical spectroscopy.

11

Porous material produced by ceramic injection molding

Matula G., Krzysteczko J.

Journal of Achievements in Materials and Manufacturing Engineering

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2015

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Vol. 71, nr 1

14--21

EN

Purpose: The aim of this research is presented the process of alumina injection molding with a multicomponent binder system based on polymer (polypropylene – PP/polyethylene- HDPE), paraffin wax (PW) and stearic acid (SA). Debinding and sintering process was also studied. Design/methodology/approach: The volume fractions of powder in the feedstocks were 50%vol and the volume of polypropylene and polyethylene were changed from 0-22%vol. The concentrations of SA were kept at 6%vol. The feedstock was heated to melt the binder and injected into a mold. Debinding process was carried out after injection step. The organic part was removed through combination of solvent and thermal debinding. Samples were sintered at 1200-1600°C in one cycle with debinding process. Findings: Thermogravimetric analysis (TGA) was performed to determine decomposition temperatures of polypropylene, polyethylene, paraffin wax and stearic acid. Morphology of alumina powder by scanning electron microscopy (SEM) was disclosed. The microstructure and properties was tested to see how the selected sintering parameter ,as a temperature, affects the structure. Originality/value: The paper presents ceramic injection molding process of alumina parts and sintering to produce porous material which is possible to use as a preform for infiltration by aluminium alloys.

12

Device simulation and multi-objective genetic algorithm-based optimization of germanium metal-oxide-semiconductor structure

Chen C.-Y., Li Y.

Computer Methods in Materials Science

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2015

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Vol. 15, No.1

258--263

EN

Germanium (Ge) and high-K dielectric materials draw many attentions due to their fascinating electrical characteristics comparing with silicon (Si) material. However, in physical and electrical simulation, the physical model may have deviation to reality case due to the process condition and manufacturing technology. To computationally study the device with Ge material, it is necessary to optimize the theoretical result with experimental data. This paper originally provides a new method to examine the static characteristic of Ge metal-oxide-semiconductor field effect transistors (MOSFETs) with aluminum oxide (Al203) by integrating device simulation, multi-objective evolutionary algorithm (MOEA), and unified optimization framework (UOF). To deal with the realistic problem, especially for the steep change of capacitance, we consider not only residual sum of squares (RSS) (i.e. the sum of squares of residuals) function but also physically crucial points in the optimization problem. Comparing to single-objective genetic algorithm (GA) with a weighted fitness, the preliminary result of this study shows the method has great improvement to optimize the suitable parameters which not only minimize the RSS of capacitance but also agree the key capacitance values from physical view.

PL

German (Ge) i materiały o wysokiej stałej dielektrycznej są interesujące ze względu na swoje niezwykle ciekawe charakterystyki elektryczne w porównaniu do krzemu (Si). Jednakże w symulacjach fizycznych i elektrycznych, model fizyczny może odbiegać od przypadku rzeczywistego ze względu na warunki procesu i technologię produkcji. Badania z wykorzystaniem metod obliczeniowych dla urządzeń wykonanych z germanu wymagają optymalizacji wyników teoretycznych z danymi doświadczalnymi. W pracy zaproponowano metodę badania statycznych charakterystyk tranzystorów polowych z tlenku germanu - półprzewodnika (MOSFETs) z tlenkiem aluminium (A1203), z wykorzystaniem zintegrowanego systemu składającego się z urządzenia do symulacji charakterystyk elektrycznych półprzewodników, wielokryterialnego algorytmu ewolucyjnego (MOEA) oraz zunifikowanej platformy do optymalizacji (UOF). Dla rozwiązania rzeczywistego problemu, zwłaszcza przy gwałtownej zmianie pojemności, w zadaniu optymalizacji rozważano nie tylko sumę kwadratów reszt (RSS), ale również kluczowe, z punktu widzenia fizyki, aspekty. W porównaniu z jednokryterialnym algorytmem genetycznym (GA) z ważoną funkcją dopasowania, wyniki przeprowadzonych badań pokazały, że opracowana meto¬da, która minimalizuje nie tylko błąd RSS dla pojemności, ale także bierze pod uwagę kluczowe wartości pojemności z fizycznych obserwacji, znacznie poprawiła zadanie optymalizacji wybranych parametrów zagadnienia.

13

Surface morphology and optical properties of Al₂O₃ thin films deposited by ALD method

Dobrzański L. A., Szindler M., Szindler M.M.

Archives of Materials Science and Engineering

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2015

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Vol. 73, nr 1

18--24

EN

Purpose: The paper presents the results of investigations on the changes in surface morphology, roughness, and thickness of the prepared aluminium oxide thin films as dependent on conditions of the thin films preparation. Design/methodology/approach: Thin films have been prepared with use of atomic layer deposition (ALD) method. The changes of surface morphology have been observed in topographic images performed with the atomic force microscope (AFM). Obtained roughness parameters have been calculated with XEI Park Systems software. The thickness distribution have been measured with spectroscopic ellipsometry. The optical transmission spectra have been measured with UV-Vis spectrophotometry. Findings: Results and their analysis show that the atomic layer deposition method allows the deposition of homogenous thin films of Al2O3 with the desired geometric characteristics and good optical properties. Practical implications: The technology of atomic layer deposition of aluminium oxide thin films causes that mentioned thin films are good potential material for optics, optoelectronics and photovoltaics. Originality/value: The paper presents results of investigations on aluminum oxide thin films prepared with atomic layer deposition method on glass substrate.

14

Infrared stimulated luminescence (IRSL) properties of natural aluminum corrosion

Şahiner. E., Meriç N.

Geochronometria

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2012

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Vol. 39, no. 3

227-232

EN

In this paper, the infrared stimulated luminescence (IRSL) property of naturally corroded aluminum and its possible applications in retrospective dosimetry have been briefly studied. Results are interesting, in particular with regard to the efforts of finding new and widely available materials for accident dosimetry. For aluminum corrosion, the dose response was found to be approximately linear between 2-80 Gy and to reach saturation before 300 Gy. The signal also showed good repro-ducibility without significant fading over storage durations of up to four mounts at room temperature. In addition to the luminescence, the corrosion samples were also analysed by X-ray Fluorescence (XRF) and X-ray Diffraction (XRD), but conclusive identification of the luminescent phase could not be made. It is concluded that the IRSL signals of this material can be favourable for dosimetry research.

15

Electric strength of air and sulphur hexafluoride in the system with electrodes covered with dielectric double layer

Zakrzewski S., Opydo W.

Computer Applications in Electrical Engineering

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2012

|

Vol. 10

394--401

EN

The paper presents the results of the study on the effect of dielectric double layer at electrode surface on electric strength of compressed air and compressed sulphur hexafluoride. The research has been carried out at alternate voltage of 50 Hz frequency. It was found that thin insulation coating laid on electrode surface, composed of aluminum oxide layer with a layer of electro-insulation polyester lacquer significantly improves electric strength of air and sulphur hexafluoride. It was found that maximum growth of electric strength of these gases was caused by the coating under their pressures exceeding the atmospheric one (3·105 and 5·105 Pa). The changes in configuration of electrode surface of the insulation systems caused by sparking over have been examined with scanning laser confocal microscope.

16

The effect of aluminum oxide layer located at the electrode surface on the electric strength of an insulation system provided with sulphur hexafluoride

Zakrzewski S., Opydo W.

Poznan University of Technology Academic Journals. Electrical Engineering

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2011

|

No. 67-68

123-129

EN

The paper presents investigation results of the effect of aluminum oxide layer located at the electrode surface on the electric strength of an insulation system with sulphur hexafluoride (SF6) subject to alternate voltage of 50 Hz frequency. The tests have been carried out under the SF6 pressure of 1*105, 3*105 and 5*105 Pa. It was found that in case of the insulation system with SF6 the electrode surface covered with the aluminum oxide layer improves the electric strength of the system, from 12 to 30 percent, according to the gas pressure. The electrode surface covered with double insulation layer composed of aluminum oxide and polyurethane or silicon paint gave still better improvement of the strength of the SF6 insulation system. In order to determine the parameters of the formula describing the mathematical dependence of the electric strength of the considered systems on the applied pressure the Statistica computer software has been used.

17

Wytwarzanie i charakteryzacja cienkich warstw tlenku hafnu dla zastosowań w technologii MOSFET w węgliku krzemu

Taube A., Korwin-Mikke K., Gutt T., Małachowski T., Pasternak I., Wzorek M., Łaszcz A., Płuska M., Rzodkiewicz W., Piotrowska A., Gierałtowska S., Sochacki M., Mroczyński R., Dynowska E., Szmidt J.

Elektronika : konstrukcje, technologie, zastosowania

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2011

|

Vol. 52, nr 9

117-120

PL

W pracy przedstawiono wyniki charakteryzacji cienkich warstw tlenku hafnu wytwarzanych metodą ALD. Zbadano wpływ wygrzewania na parametry elektrofizyczne warstw HfO₂ oraz HfO₂/SiO₂ oraz wpływ zastosowania warstwy podkładowej na właściwości elektryczne struktur MIS z warstwa tlenku hafnu osadzoną na węgliku krzemu. Zastosowanie warstwy podkładowej z SiO₂ znacznie poprawiło parametry kondensatorów MIS na węgliku krzemu, zmniejszając prąd upływu oraz gęstość ładunku efektywnego w dielektryku. Zaobserwowano zwiększenie się pola przebicia do wartości 7.2 MV/cm. Wygrzewanie warstw HfO₂/SiO₂ w temperaturze 400°C zwiększyło ich niezawodność oraz zredukowało gęstość stanów powierzchniowych do 4×10¹¹ eV⁻¹ cm⁻². Wygrzewanie warstw HfO₂ w 400°C obniżyło prąd upływu przy jednoczesnym zwiększeniu względnej przenikalności elektrycznej.

EN

This work presents the results of characterization of thin hafnium oxide films fabricated by ALD. Effect of annealing on physical properties on HfO₂ and HfO₂/SiO₂ layers, as well as effect of introduction of pedestal layers on properties of 4H-SiC MIS capacitor was investigated. Introduction of SiO₂, pedestal layer improved properties of 4H-SiC MIS capacilors, causing decreasing of leakage current and effective charge density in the insulator. Electric breakdown field was increased from 4 7 to 7.2 MV/cm. Annealmg of HfO₂/SiO₂ layers m 400°C improved reliability and reduced density of interface traps. Annealing of HfO₂ - layers m 400°C caused decreasing of leakage current and increased of relative permittivity.

18

Wytwarzanie kompozytu wielowarstwowego Al-Al2O3

Sobiecki J.R., Tomassi P.

Kompozyty

|

2006

|

R. 6, nr 3

20-25

PL

Przedstawiono wyniki badań dotyczące możliwości wytwarzania kompozytu warstwowego Al-Al2O3 otrzymanego na drodze utleniania elektrochemicznego oraz zastosowania metody zgrzewania dyfuzyjnego krążków z tak wytworzonymi warstwami tlenkowymi. Połączenie tych metod doprowadziło do powstania materiału warstwowego, w którym warstwy tlenku glinu są rozproszone w stopie aluminium. Stwierdzono, że zastosowanie tzw. procesu uszczelniania powłok tlenkowych nie wpływa na ich odporność korozyjną, a ponadto uniemożliwia powstawanie złącza w procesie zgrzewania dyfuzyjnego. Badania metalograficzne oraz składu chemicznego otrzymanego materiału wykazały, iż optymalną temperaturą wytwarzania kompozytu jest temperatura 580°C przy ciśnieniu 4 MPa w czasie 2 h. W tych warunkach wytworzony kompozyt warstwowy charakteryzował się brakiem porów w strefie złącza. Zmniejszenie grubości wytwarzanych powłok powoduje lepsze połączenie warstw poprzez obecność nieciągłości powłok tlenkowych w strefie połączenia.

EN

The paper presents the results of investigations which are concerned with possibility of obtaining the laminar composite Al-Al2O3 produced by electrochemical oxidation and diffusion welding of samples with produced oxide layers. The combining of these methods leads to create laminar composite in which the aluminum oxide layers are dispersed in the aluminum alloy. The oxide layers produced by electrochemical oxidation significantly improves the corrosion resistance of aluminum (Fig. 3). It has been established that the application of seal after the obtaining the oxide layers does not influence on corrosion resistance but makes impossible to join properly the produced layers. The metallographic (Fig. 4) and chemical composition examinations (Fig. 5) proved that the optimum temperature of welding is 580°C, the pressure is 4 MPa and the time 2 h. The apparatus is shown in Figure 1. These conditions caused the formation of laminar composite with no pores in the joined zone. The decrease of the thickness of oxide layers improves the joining of them by the presence of discontinuity in connecting zone (Fig. 5c). But it must be underlined that the joining the ceramic oxide layers 20 (im thick between themselves succeeded (Figs. 4b and 5b). The attempt of joining four samples with thinner aluminum oxide layers was also effective (Figs. 5b, c).

19

Wpływ dyspersyjnej fazy ceramicznej na właściwości niklowych warstw kompozytowych

Wyszyńska A., Trzaska M.

Kompozyty

|

2004

|

R. 4, nr 9

94-98

PL

Zbadano i oceniono wpływ dwóch różnych dyspersyjnych faz ceramicznych Si3N4 i Al2O3 na właściwości kompozytowych warstw niklowych wytworzonych metodą redukcji chemicznej. Przedstawiono wyniki analiz morfologicznej i rentgenowskiej proszków azotku krzemu i tlenku glinu stosowanych do wytwarzania warstw kompozytowych. Przedstawiono także topografię i morfologię powierzchni wytworzonych warstw Ni-P-Si3N4 i Ni-P-Al2O3 oraz ich strukturę w przekroju poprzecznym. Zaprezentowano wyniki badań twardości oraz odporności na zużycie przez tarcie materiału podłoża S235JR oraz warstw Ni-P, Ni-P-Si3N4, Ni-P-Al2O3. Analiza porównawcza wyników badań warstw Ni-P, Ni-P-Si3N4 oraz Ni-P-Al2O3 wykazała, że wbudowanie dyspersyjnej fazy ceramicznej w warstwę Ni-P powoduje istotne zwiększenie twardości oraz odporności na zużycie ścierne materiału warstwy kompozytowej. W przypadku badanych materiałów stwierdzono również taki sam wpływ zarówno tlenku glinu, jak i azotku krzemu na właściwości mechaniczne warstwy.

EN

The paper is aimed on investigations of the influence of two kinds of ceramic dispersive phases i.e. Si3N4 and Al2O3 on properties of composite nickel coatings manufactured by the method of chemical reduction. Investigations of the morphology and phase composition of Si3N4 and Al2O3 powders are performed (Figs 1 and 2). Results of morphological examinations of the coating surfaces Ni-P, Ni-P-Si3N4 and Ni-P-Al2O3 are shown in Figure 3. Structures in cross sections of the composite coatings are shown in Figure 4. Effects of examinations of the wear resistance and hardness of the S235JR substrate and Ni-P, Ni-P-Si3N4 as well as Ni-P-Al2O3 coatings are reported (Fig. 5 and Tab. 1). Results of performed investigations of Ni-P--Si3N4 coatings are compared with results of similar examinations of Ni-P-Al2O3 surface deposits. Results of investigations presented in this paper have showed that introducing ceramic phases into Ni-P coatings leads to important increase in wear resistance and hardness of the ceramic dispersive phase has influences on mechanical properties of the composite surface coatings.

20

Kompozyty ceramiczne formowane z wykorzystaniem wybranych reakcji enzymatycznych

Tomaszewska-Grzęda A., Szafran M.

Kompozyty

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2004

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R. 4, nr 11

297-301

PL

Proces kontrolowanej koagulacji mas lejnych pod wptywem reakcji enzymatycznych (Direct Coagulation Casting) jest od kilku lat tematem prac prowadzonych w Zespole Ceramiki Specjalnej Zakładu Technologii Nieorganicznej i Ceramiki Wydziału Chemicznego Politechniki Warszawskiej. Polega on na zateżaniu masy lejnej poprzez wewnętrzną powolną zmianę pH (będącą wynikiem rozkładu pewnych substancji pod wpływem enzymów) wokół każdej cząstki proszku ceramicznego, co jest przyczyną zmiany budowy podwójnej warstwy elektrycznej wokół tego proszku zawieszonego w rozpuszczalniku. W pracy przedstawiono wyniki badań nad otrzymywaniem kompozytów ceramicznych na drodze kontrolowanej koagulacji ceramicznych mas lejnych z Al2O3, nZrO2 lub mieszaniny wodorotlenków cyrkonu, hafnu i itru. Praca polegała na otrzymaniu i zbadaniu właściwości kompozytów zawierających 95% obj. tlenku glinu i 5% obj. domieszki nZrO2, wprowadzonej na dwa sposoby - jako proszek i jako "żel", a następnie na porównaniu otrzymanych wyników. W tabeli 1 przedstawiono wyniki badań kształtek surowych otrzymanych z ceramicznych mas lejnych z tlenku glinu, z tlenku glinu z 5% dodatkiem nanoproszku tlenku cyrkonu oraz z tlenku glinu z dodatkiem "żelu" o całkowitym stężeniu fazy stałej 54,3% obj., a w tabelach 2-5 - kształtek spiekanych. Rysunki 1-4 przedstawiają kolejne powiększenia kształtki spiekanej otrzymanej metodą DCC z tlenku glinu i "żelu". Uzyskane wyniki badań wskazują na trafność wyboru mieszaniny wodorotlenków cyrkonu, hafnu i itru jako składników kompozytu Al2O3-nZrO2 w miejsce wcześniej stosowanego nZrO2.

EN

The direct coagulation casting by means of enzymatic reactions is the subject of research carried out m the Department of Specialty Ceramics of the Warsaw University of Technology Faculty of Chemistry Division of Inorganic Technology and Ceramics. This method consists in the concentration of the casting slip by internal, slow change of pH (resulting from the decomposition of certain substances by means of enzymes) round each particle of the ceramic powder. This is the reason for the change in the structure of the double electric layer round this powder suspended in a solvent. In the work the results of studies on the obtaining of ceramic composites by direct coagulation casting of slips with Al2O3, nZrO2 or a mixture of zirconium, hafnium and yttrium hydroxides are presented. The work consisted in the obtaining and studying the properties of composites comprising 95 vol.% of aluminum oxide and 5 vol.% of the ZrO2 additive, introduced by two methods - as a powder and as a "gel", and the comparison of the results obtained. Table 1 shows the results of studies of green samples obtained from ceramic casting slips with aluminum oxide, aluminum oxide with a 5 % additive of zirconium oxide nanopowder, and with aluminum oxide with the addition of a gel of total solid phase concentration of 54.3 vol.%. Tables 2-5 show the results of studics of sintered samples. Figures 1-4 show consecutive magnifications of the sintered sample obtained by the DCC method from aluminum oxide and gel. The obtained results of studies show the relevancy of selecting the mixture of zirconium, hafnium and yttrium hydroxides as components of the Al2O3-nZrO2 composite, instead of the earlier used nZrO2.