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1

LTCC glass-ceramics based on diopside/cordierite/Al2O3 for ultra-high frequency applications

Synkiewicz-Musialska Beata

Scientiae Radices

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2023

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Vol. 2, Iss. 2

190--201

EN

In this work, three glass-ceramic composites based on a commercial SiO2-B2O3-Al2O3-CaO-MgO glass and cordierite, diopside or Al2O3 were used for preparation of green tapes and low temperature cofired ceramics (LTCC) substrates. The thermal behavior, phase composition, microstructure and dielectric properties of the fabricated glass-ceramics were characterized using a heating microscope, thermal analysis, X-ray diffraction, scanning electron microscopy and time domain spectroscopy. The applicability of the developed materials for LTCC technology was demonstrated by the preparation of test multilayer substrates. The glass-ceramic substrates exhibit advantageous properties for ultra-high frequency LTCC applications, including low sintering temperatures of 900-980°C, good compatibility with commercial Ag and AgPd conductive pastes and a low dielectric permittivity of 3.5-7 at 1 THz.

2

Projektowanie efektywnego katalizatora reakcji uwodornienia acetylenu do etylenu poprzez dobór prekursora i nośnika

Plis Anna, Kleszcz Mateusz, Samardakiewicz Bartłomiej, Rutkowski Rafał, Połczyński Piotr, Lewera Adam, Jurczakowski Rafał

Przemysł Chemiczny

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2023

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T. 102, nr 11

1169--1176

PL

Przedstawiono wyniki badań selektywnego uwodornienia acetylenu w obecności katalizatorów zawierających pallad jako fazę aktywną. Jako nośniki zastosowano porowate matryce Al₂O₃ oraz mieszaniny Al₂O₃ i zeolitu Beta. W pracy zbadano także wpływ prekursora palladu, czyli kompleksów chlorkowych i azotanowych(III) palladu(II) na właściwości katalityczne otrzymanych materiałów. Badania katalityczne przeprowadzono w skali laboratoryjnej w reaktorze odzwierciedlającym proces przemysłowy. Najwyższą aktywność i selektywność katalizatora uzyskano w obecności katalizatora otrzymanego w wyniku adsorpcji kompleksów azotanowych(III) palladu(II) na nośniku Al₂O₃.

EN

Pd catalysts were obtained by impregnating chloride or nitrate(III) complexes of Pd(II) on Al₂O₃ or zeolite Beta or Al₂O₃ and zeolite Beta mixt. as supports. In a laboratory installation simulating an industrial process, catalytic tests were carried out in the reaction of selective hydrogenation of acetylene at a concn. of 4% vol. in ethylene. The highest activity and selectivity were achieved in the presence of a catalyst obtained by adsorption of Pd nitrate(III) complexes on an Al₂O₃ support.

3

Manufacture of Toughened Al2O3-Based Composites by the Combination of RBAO and SPS Processes

Rocha-Rangel Enrique, Calles-Arriaga Carlos A., López-Hernández Juan, Rodríguez-García José A.

Archives of Metallurgy and Materials

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2023

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Vol. 68, iss. 1

249--255

EN

The effect of additions of silver or titanium (0.5 or 3 vol.%) microparticles on the microstructure, as well as some physical properties of Al2O3-based composites, were studied. The processing method for the manufacturing of alumina-based composites was a combination of RBAO and SPS processes. After the SPS process, bodies with almost full density were obtained. Observations by optical microscopy show a very fine and homogenous microstructure in all samples. Concerning mechanical properties, the addition of metals on alumina increases its fracture toughness significantly (112% for the sample with additions of silver, while the composite with additions of titanium fracture toughness increases by 72%). In terms of optical properties, both silver and titanium improve the absorbance in the visible range.

4

Plasma welding of aluminum in an oxygen-free argon atmosphere

Klett Jan, Bongartz Benedict, Wolf Thomas, Hao Chentong, Maier Hans Jürgen, Hassel Thomas

Advances in Materials Science

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2023

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Vol. 23, nr 1(75)

5--18

EN

Plasma welding is characterized by a high concentration of energy, which allows for high welding speed and leads to less distortion and residual stresses compared to conventional welding processes. Due to the local and controlled heat input, the process is suitable for sheet metal from ≈ 0.1 mm (micro plasma) up to ≈ 10 mm. In the case of aluminum and its alloys, the natural aluminum oxide layer on the metal surface limits the productivity of the plasma welding process. The electrically isolating and thermally insulating Al2O3 layer has a significantly higher melting point compared to the aluminum (Tm(Al2O3) = 2072 °C vs. Tm(Al) = 660 °C). The oxide layer hinders the formation of a stable arc and can even impede the joining formation. In order to remove the oxide layer and to produce quality welds with a DC process, it is necessary to weld with reverse polarity to use the principle of cathodic surface cleaning. However, this leads to increased electrode wear and increased penetration depth, which is not always desirable. In the study presented, the use of silane to reduce the oxygen content in the welding atmosphere as well as to remove the natural aluminum oxide layer on the metal surface was investigated. As previous studies have shown that the use of silane-doped plasma-gases is suitable for removing the superficial oxide layer on aluminum components, high-quality welded joints were expected. Quality welds with sufficient dilution were achieved using a transferred arc silane-doped helium plasma. In contrast, welding with an argon-silane mixture led to excessive pores formation. Additionally challenges to stabilize the arc process were identified and ramifications with respect to process optimization are discussed.

5

Properties of Al2O3 Ceramic Coatings Applied by ALD Method on 100Cr6 Steel

Radoń-Kobus Krystyna, Madej Monika

Tribologia

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2022

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nr 2

45--53

EN

The purpose of the paper was to assess the morphology, chemical composition, geometric surface structure and contact angle, as well as to analyse the tribological properties of Al2O3 coatings deposited on 100Cr6 steel using the technique of atomic layers ALD. Al2O3 coatings were selected due to their tribological properties, adhesion to the substrate and hardness. Tribological tests were performed in a reciprocating motion in a ballon-disc combination, with a counter-specimen of 100Cr6 steel, under the conditions of technically dry friction. Surface morphology was observed under a scanning microscope, and an EDS analyser enabled the performance of an analysis of the chemical composition of the samples. Wetting of the surface of the Al2O3 coating was determined by means of an optical strain gauge. The geometric surface structure before and after the tribological tests was analysed by means of a confocal microscope with an interferometric mode. The tests proved that during technically dry friction, the average coefficient of friction for the Al2O3 coating is lower by approximately 30% than for 100Cr6 steel. The tested coatings are characterised by hydrophobicity.

PL

Celem pracy była ocena morfologii, składu chemicznego, struktury geometrycznej powierzchni, kąta zwilżania oraz analiza właściwości tribologicznych powłok Al2O3 osadzanych na stali 100Cr6 techniką warstw atomowych ALD. Powłoki Al2O3 wytypowano ze względu na ich właściwości tribologiczne, adhezję do podłoża oraz twardość. Testy tribologiczne przeprowadzono w ruchu posuwisto-zwrotnym w skojarzeniu kula–tarcza z przeciwpróbką ze stali 100Cr6 w warunkach tarcia technicznie suchego. Na mikroskopie skaningowym obserwowano morfologię powierzchni, a analizator EDS umożliwił przeprowadzenie analizy składu chemicznego próbek. Przy pomocy tensjometru optycznego określono zwilżalność powierzchni powłoki Al2O3. Strukturę geometryczną powierzchni przed i po testach tribologicznych analizowano za pomocą mikroskopu konfokalnego z trybem interferometrycznym. Testy wykazały, że podczas tarcia technicznie suchego średni współczynnik tarcia dla powłoki Al2O3 jest około 30% mniejszy niż dla stali 100Cr<6. Badane powłoki charakteryzują się hydrofobowością.

6

Bonding methods of ceramic materials with deposited carbon layers

Matusiak Tomasz, Kaszczyszyn Jakub, Dąbrowski Arkadiusz

Przegląd Elektrotechniczny

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2022

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R. 98, nr 1

55--58

EN

In this paper, we present a proposed bonding technology of ceramic materials. It could be applied for manufacturing the excitation source for detection of elements by means of Optical Emission Spectroscopy (OES) method. The biggest challenge was choice of proper bonding technology for materials with screen printed carbon layers as an excitation electrodes. It was caused by a need to avoid a deterioration of electrical properties of the carbon layer during the bonding process. The bonding at low temperature with various glaze layers was verified with addition of noble elements and plasma modification. The results were promising, without any significant destruction of carbon layers.

PL

W tym artykule przedstawiamy proponowaną technologię łączenia materiałów ceramicznych która może być zastosowana przy wytwarzaniu źródła wzbudzenia do detekcji pierwiastków w metodzie optycznej spektroskopii emisyjnej. Wybór odpowiedniej technologii łączenia materiału z warstwami węglowymi wytwarzanymi metodą sitodruku był wyzwaniem z powodu konieczności uniknięcia degradacji właściwości elektrycznych węgla podczas procesu łączenia. Zweryfikowano łączenie w niskiej temperaturze z różnymi warstwami szkliwa z dodatkiem pierwiastków szlachetnych i modyfikacją plazmową. Wyniki były obiecujące, bez znacznego zniszczenia warstw węglowych.

7

Effect of Charging and Discharging Process of PCM with Paraffin and Al2O3 Additive Subjected to Three Point Temperature Locations

Kumar Sunil K., Muniamuthu Sumathy, Mohan A., Amirthalingam P., Anbu Muthuraja M.

Journal of Ecological Engineering

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2022

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Vol. 23, nr 2

34--42

EN

This analysis focused on investigating thermal storage behaviour on phase change material along with Al2O3 as an additive. The experimental investigation was performed by three set temperature points, i.e. 40 °C, 50 °C and 60 °C with the mass circulation rate through the tank of 5 kg/min, 3 kg/min and 2 kg/min. The forced circulation method was used to circulate the liquid, water was used as a working medium and Al2O3 as nano particle. Paraffin acts a phase change material to conduct the experimental procedure. The combination of paraffin with Al2O3 improves the latent heat storage of the material. The performance, with respect to charging and discharging of the material, was investigated and it was observed that the temperature location point of 50 °C shows the best results in terms of charging and discharging phenomena, compared to other two temperature location points. During the process of charging, the maximum rate of heat transfer can be achieved by Al2O3 nanofluids. Paraffin along with Al2O3 are characterized by the best thermal storage behaviour during the latent heat storage at charging process and dissipation of heat during discharge process. The rapid cooling comparison for three set location points has been studied and best solidification was achieved at the point of 60 °C; this is due to the rapid cooling at higher elevation temperatures. The energy that was stored in thermal form is to be transferred with the aid of heat exchanger, a special type heat exchanger employed in this analysis to transfer the heat. From this analysis it is concluded that paraffin with Al2O3 are characterized by the best performance in terms of the charging and discharging phenomenon.

8

Fabrication of a high wear resistance AA7075/AL2O3 composites via liquid metallurgy process

Sivaraman R., Jalil Abduladheem Turki, Aravindhan Surendar, Nan Zhao, Vini M. Heydari, Daneshmand S.

International Journal of Applied Mechanics and Engineering

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2022

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Vol. 27, no. 4

205--210

EN

In the present study, AA7075/Al2O3 composites have been fabricated via liquid metallurgy process. AA7075 alloy and Al2O3 particles were taken as the base matrix and reinforcements, respectively. Then, contents of 3 and 6 wt. % of Al2O3 subdivisions were added into the AA7075 matrix. To improve wettability and distribution, reinforcement particles were pre-heated to a temperature of 550°C for each composite sample. A hardened EN32 steel disc as the counter face was used to evaluate the wear rate pin-on-disc. The results showed that the wear rate of the AA/Al2O3 composites was smaller than that of the monolithic AA7075 samples. Finally, the worn surfaces of samples were investigated by SEM.

9

Synthesis of magnesium aluminate spinel doped TiO2 from magnesite waste

Canikoğlu Nuray

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 1

311--316

EN

Magnesium aluminate spinel (MgAl2O4) is an important refractory material of magnesia origin. It is formed by the reaction of magnesium and aluminum oxides. In this study, TiO2 was added to magnesite waste and alumina (Al2O3) powders in different proportions and the mixtures were sintered at different temperatures after shaping. The aim of this study was to produce spinel economically by recycling waste materials. Therefore, titanium dioxide (TiO2) added magnesium aluminate spinel was produced and the products obtained were characterized by XRD and SEM-EDS analyses. In addition, bulk density, apparent porosity and microhardness values were measured and the effects of TiO2 additive on magnesium aluminate properties were examined. The better values were determined in samples doped 4 wt.% TiO2 at the sintering temperature of 1400°C.

10

Selected Construction Properties of Hybrid Epoxy Composites Reinforced with Carbon Fiber and Alumina

Krzyżak Aneta, Relich Szymon, Kosicka Ewelina, Szczepaniak Robert, Mucha Mateusz

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 2

240--248

EN

The purpose of this study is to investigate the impact of the introduction of powder modifier into composite reinforced with carbon fabric on selected mechanical properties. The tests were performed on 16 groups of hybrid epoxy composites, including one reference group and 15 groups containing alumina with the grain size of F220, F240, F280, F320 and F360, added in the weight percent of 5%, 10% and 15%. This composite was made of certified components designed for application in the aviation industry. Test results indicated that an increase of alumina content by weight caused a decrease of strength of polymer composites in most tests. In addition, the value of the force transferred by the composite in the tensile test increased disproportionately to the cross section, which resulted in decreased strength, while the addition of alumina impeded the super-saturation of the carbon fabric, which caused discontinuities in the matrix material.

11

Thermal gravimetric analysis of glass fiber reinforced composite for understanding the impact of copper oxide in relation to titanium oxide filler particles

Alam Shahinoor, Chowdhury Mohammad Asaduzzaman

Composites Theory and Practice

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2021

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R. 21, nr 1-2

12--21

EN

In this work, the composite samples required to investigate their thermal properties were fabricated employing the conventional hand lay-up technique, followed by a light compression molding process. A fixed weight of plain woven glass fiber and epoxy with four different types of fillers as calcium carbonate (CaCO3), aluminum oxide (Al2O3), magnesium oxide (MgO) and titanium oxide (TiO2) or copper oxide (CuO) of different weights (5, 10 and 15 g) were studied. According to thermal gravimetric analysis (TGA), it was observed that the melting point (Tm) and glass-transition temperature (Tg) are affected by the presence of CuO and TiO2, which indicate the degree of composite crystallinity established by the stronger interfacial interaction by the CuO than that of the TiO2 particles and the amorphous region of the chain. These studies were supported by examination of the surface morphology of the composites by means of scanning electron microscopy (SEM).

12

Effect of TiO₂ on the microstructure and phase composition of Al₂O₃ and Al₂O₃–TiO₂ APS sprayed coatings

Michalak Monika, Łatka Leszek, Sokołowski Paweł, Candidato Rolando T., Ambroziak Andrzej

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 2

art. no. e136735

EN

Plasma sprayed ceramic coatings serve as protective layers and are frequently exposed to aggressive wear, corrosion, or high-temperature environment. Currently, alumina and alumina-titania are some of the most popular protective ceramic composite coatings used in the industry. The present work deals with the investigation of the influence of TiO₂ content in the feedstock powder on the resulting microstructure and properties of Al₂O₃, Al₂O₃ + 3 wt% TiO₂, Al₂O₃ + 13 wt% TiO₂ and Al₂O₃ + 40 wt% TiO₂ coatings developed via atmospheric plasma spraying (APS). Specifically, the phase composition, morphology, and microstructure, as well as the mechanical and tribological performance of the coatings were examined. Results revealed that higher content of TiO₂ induced the transformation of phases, leading to the formation of intermediary Al₂TiO₅ and Al₂- xTi₁- xO₅ phases. Also, the dominant α–Al₂O₃ to γ–Al₂O₃ transformation confirmed the formulation of well-melted lamellas within the coating structure. It was also shown that the increase in TiO₂ content decreased the micro-hardness of the coatings due to the formation of the intermediary phases as mentioned above and thus, affected their tribological performance. The lowest volumetric wear, equal to 7.2×10⁻⁵ mm³/(N ∙ m), was reported for Al₂O₃ + 13 wt% TiO₂ coating.

13

Effects of ZrO2 and Al2O3 Addition on the Physical Properties of Cu-Mo-Cr Alloy by Liquid Phase Sintering

Cho Yeong-Woo, Sim Jae-Jin, Heo Sung-Gue, Kim Hyun-Chul, Lee Yong-Kwan, Byeon Jong-Soo, Lee Yong-Tak, Lee Kee-Ahn, Seo Seok-Jun, Park Kyoung-Tae

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 3

683--687

EN

In this study, the effect of the addition of ZrO2 and Al2O3 ceramic powders to Cu-Mo-Cr alloy was studied by examining the physical properties of the composite material. The ceramic additives were selected based on the thermodynamic stability calculation of the Cu-Mo-Cr alloys. Elemental powders, in the ratio Cu:Mo:Cr = 60:30:10 (wt.%), and approximately 0-1.2 wt.% of ZrO2 and Al2O3 were mixed, and a green compact was formed by pressing the mixture under 186 MPa pressure and sintering at 1250°C for 5 h. The raw powders were evenly dispersed in the mixed powder, as observed by scanning electron microscopy. After sintering, the microstructures, densities, electrical conductivities, and hardness of the composites were evaluated. We found that the addition of ZrO2 and Al2O3 increased the hardness and decreased the electrical conductivity and density of the composites.

14

Evaluation of TiN Coating Properties Deposited on HS6-5-2C Steel

Kowalczyk Joanna

Tribologia

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2020

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nr 3

23--31

EN

The article presents selected properties of TiN coating on HS6-5-2C steel by Physical Vapour Deposition (PVD). The coating thickness was measured with a Calotest, and its hardness was measured with a nanohardness tester. Tribological parameters were determined, namely, the coefficient of friction and linear wear on the TRB3 tester operating in a ball-on-disk sliding friction pair. The disc was made of HS6-5-2C steel with a TiN coating and the ball of 100Cr6 steel without coating and with a-C:H coating, with Al2O3. The tests were performed under technically dry friction conditions. The coating structure observations were made using a scanning microscope, and the analysis of the geometric structure of samples, before and after tribological tests, were performed with an optical profile measurement gauge. The test results showed that the lowest linear wear was obtained for friction pairs with an Al2O3 ball and a steel ball with a-C:H coating applied.

PL

W artykule przedstawiono wybrane właściwości powłoki TiN osadzonej na stali HS6-5-2C techniką fizycznego osadzania z fazy gazowej PVD. Zmierzono grubość powłoki przy użyciu Calotestera oraz jej twardość za pomocą nanotwardościomierza. Określono parametry tribologiczne, a mianowicie współczynnik tarcia i zużycie liniowe na testerze TRB3 pracującym w skojarzeniu trącym kula–tarcza w ruchu ślizgowym. Tarcza wykonana była ze stali HS6-5-2C z powłoką TiN, a kula ze stali 100Cr6 bez i z naniesioną powłoką a-C:H, z Al2O3. Badania wykonano w warunkach tarcia technicznie suchego. Obserwacje struktury powłoki zrealizowano przy użyciu mikroskopu skaningowego, a analizę struktury geometrycznej powierzchni próbek przed i po testach tribologicznych wykonano profilometrem optycznym. Wyniki badań wskazały, że najmniejsze zużycie liniowe uzyskano dla par trących z kulą wykonaną z Al2O3 oraz stalową z naniesioną powłoką a-C:H.

15

Determination of the thickness of BN layers on the Al2O3 substrate by FT-IR spectroscopy

Możdżonek Małgorzata, Caban Piotr .A., Gaca Jarosław, Wójcik Marek, Piątkowska Anna

Materiały Elektroniczne

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2020

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T. 48, nr 1-4

15--20

EN

Hexagonal boron nitride (h-BN) is an attractive material for applications in electronics. The technology of devices based on BN requires non-destructive and fast methods of controlling the parameters of the produced layers. Boron nitride layers of different thickness were grown on sapphire substrates (Al2O3) using the MOCVD method. The obtained films were characterized by FT-IR spectroscopy using IRR and ATR techniques and by the XRR and SEM methods. We showed that by analyzing the ATR or reflectance spectrum in the range of 600-2500 cm-1 we can measure the thickness of a BN layer on the Al2O3 substrate. Our measuring method allows measuring the layers with a thickness from ~2 nm to approx. 20 nm.

PL

Heksagonalny azotek boru (h-BN) jest atrakcyjnym materiałem do zastosowań w elektronice. Technologia wytwarzania urządzeń z zastosowaniem warstw h-BN wymaga nieniszczących i szybkich metod kontroli parametrów produkowanych warstw. Warstwy azotku boru o różnej grubości wyhodowano na podłożach szafirowych metodą MOCVD. Otrzymane warstwy scharakteryzowano za pomocą spektroskopii FT-IR z użyciem technik IRR i ATR oraz metodami XRR i SEM. Pokazaliśmy, że analizując widmo ATR lub odbicia w zakresie 600-2500 cm-1 można zmierzyć grubość warstwy BN na podłożu Al2O3. Nasza metoda pomiarowa pozwala na pomiar warstw o grubości od ~2 nm do ok. 20 nm.

16

Effectiveness of the low-level MgO addition in the two-stage sintering of ultrafine alumina

Moskała Norbert, Pyda Waldemar

Materiały Ceramiczne

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2020

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T. 72, nr 3

171--180

EN

Submictrometric (~0.1 µm) alumina powders, pure and doped with 0.05% or 0.5% by weight of magnesia, were cold isostatically pressed and two-stage sintered. The preliminary experiment involved selecting the T1 temperature of the two-stage sintering (TSS). This was done by analysing the grain size as a function of relative density during sintering at a constant heating rate. Thereafter, the lower TSS temperature (T2) was set to 25-50 °C below T1, and the dwell time at T2 was assumed to be in the range of 3-12 hours. A final comparison of the density and grain size between the doped and undoped two-stage sintered samples proved that the sintering effect is better for the magnesium oxide doped materials, but also showed that the effect is non-linear, and less magnesia is more beneficial. Finally, an almost fully densified MgO-doped alumina ceramics with an average grain size close to 0.5 microns was obtained. The reference, conventional sintering process (T1/3 h) also resulted in very well densified materials, but with a coarser microstructure.

PL

Submiktrometryczne (~0,1 µm) proszki tlenku glinu, czysty i domieszkowane 0,05% lub 0,5% mas. tlenku magnezu, prasowano izostatycznie na zimno i spiekano dwuetapowo. Eksperyment wstępny obejmował dobór temperatury T1 dwuetapowego spiekania (TSS). Dokonano tego przez analizę wielkości ziarna w funkcji gęstości względnej podczas spiekania ze stałą szybkością ogrzewania. Następnie ustawiono niższą temperaturę TSS (T2) na 25-50° C poniżej T1, a czas przetrzymania w T2 przyjęto w zakresie 3-12 godzin. Końcowe porównanie gęstości i wielkości ziarna pomiędzy domieszkowanymi i niedomieszkowanymi dwuetapowymi próbkami spiekanymi dwuetapowo wykazało, że efekt spiekania jest lepszy dla materiałów domieszkowanych tlenkiem magnezu, ale także pokazało, że efekt jest nieliniowy, a mniejsza ilość tlenku magnezu jest korzystniejsza. Ostatecznie otrzymano prawie całkowicie zagęszczoną ceramikę z tlenku glinu domieszkowanego MgO o średnim uziarnieniu bliskim 0,5 mikrona. Referencyjny, klasyczny proces spiekania (T1/3 godz.) również skutkował bardzo dobrze zagęszczonymi materiałami, ale o bardziej gruboziarnistej mikrostrukturze.

17

Mikrostruktura wielowarstwowej powłoki Al2O3 wytworzonej metodą plazmowego utleniania elektrolitycznego na stopie aluminium serii 2000

Michta Grzegorz, Czech Jacek

Hutnik, Wiadomości Hutnicze

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2020

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Vol. 87, nr 4

99--106

PL

W pracy przedstawiono wyniki badań powłoki Al2O3 powstałej w procesie PEO (Plasma Electrolytic Oxidation) na podłożu stopu aluminium serii 2000. Badania mikrostrukturalne wykonano przy użyciu mikroskopii świetlnej i elektronowej (SEM i TEM). Powstała powłoka tlenku aluminium charakteryzowała się budową wielowarstwową o zróżnicowanej mikrostrukturze. Wyróżniono trzy główne warstwy. Zewnętrzna warstwa składa się z kruchych krystalitów, a wewnętrzna − z dobrze przylegającej do podłoża funkcjonalnej warstwy tlenkowej. Pomiędzy podłożem duralowym a warstwą wewnętrzną zaobserwowano warstwę przejściową o budowie amorficznej. Ponadto wykonano badania adhezji powłoki do podłoża poprzez test zarysowania; badania te miały głównie charakter technologiczny związany z oceną stopnia przylegania powłoki do podłoża duralowego.

EN

This work presents results of the investigation of Al2O3 coating produced on the AA2000 series aluminium alloy using the Plasma Electrolytic Oxidation (PEO) process. Microstructural studies of the coating were performed using Light Microscopy (LM) as well as Scanning and Transmission Electron Microscopy (SEM, TEM) methods. Investigated alumina scale has a multilayer composition: three sublayers with the different structure were identified. The outer-layer composes mainly of brittle Al2O3 crystals, whereas the inner-layer exhibits excellent adhesion to the Al alloy substrate and high mechanical properties. Between the base alloy and the inner-sublayer, a transition zone with amorphous structure was found. To investigate the coating adhesion to the substrate, the scratch tests were performed, that confirmed high mechanical properties of the Al alloy-coating system.

18

The Influence of Alloying Additions on High Temperature Interaction Between Molten Compacted Graphite Iron and Alumina

Sobczak N., Bacior M., Turalska P., Bruzda G., Homa M., Sobczak J. J.

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 3

1227--1238

EN

High temperature behavior of three compacted graphite iron (CGi) alloys on polycrystalline aluminasubstrates (99.7%, porosity <3%) were examined by the sessile drop method combined with classical contact heating procedure in flowing Ar. High-speed high-resolution CCd camera was used for continuous recording of the CGi/Al2 O3 couples during melting alloy, heating to and holding the couples at the test temperature of 1450°C for 15 min and their subsequent cooling. The comparative studies were made with conventional CGi (in wt.%: 3.70 C, 2.30 Si, 0.44 Mn, 0.054 P, 0.017 Mg, 0.015 S) and two alloys additionally containing the same amounts of 0.25 Mo, 0.1 V, 0.045 Sn and 0.032 Sb with different concentrations of Mg + Cu additions, i.e. 0.01Mg + 0.33Cu and 0.02Mg + 0.83Cu. All three CGi alloys demonstrated non-wetting behavior on the Al2 O3 substrates while the contact angle values slightly decreased with increase of the Mg + Cu content in the alloy, i.e. 131° (unalloyed CGi), 130° (0.01Mg + 0.33Cu) and 125° (0.02Mg + 0.83Cu). Structural characterization of solidified couples by light microscopy and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy revealed: 1) heterogeneous nucleation of discontinuous graphite layer at the drop-side interfaces and on the surface of the drops; 2) reactively formed Mg-rich oxide layer at the substrate-side interface; 3) the formation of satellite droplets on the surface of the drops during their solidification; 4) degeneration of initially compacted graphite to lamellar graphite after remelting and subsequent solidification of the drops, particularly in their surface layer.

19

A new ceramic composite based on spherical aluminium oxide for auxiliary panels in high-temperature firing processes

Spyrka M., Atraszkiewicz R., Klimek L.

Archives of Materials Science and Engineering

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2020

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Vol. 101, nr 1

5--14

EN

Purpose: The subject of the research and investigation is a new ceramic foundry composite based on a spherical form of aluminium oxide. It is intended to limit the occurrence of technological problems related to the appropriate selection of auxiliary refractory materials, such as cracking, high heat capacity and variable coefficient of thermal expansion. Design/methodology/approach: A composite ceramic material with the spherical form of aluminium oxide included allows to reduce mass and stabilize characteristics of dimensional changes as a function of temperature in auxiliary panels in high-temperature firing processes with typical manufacturing process of the ceramics, which is gravity casting, drying and high-temperature firing. Findings: The study showed that the quantitative share of the spherical form of Al2O3 in the volume of ceramic material has a major impact on its properties. An increased share of spheres translates into greater material porosity and lower matrix density but also, by reducing the cross-section, into decreased strength properties. In the case of the developed ceramic material, there is no visible trend of a decrease in the coefficient of thermal expansion with increasing temperature, which is the case with traditional ceramic materials. Research limitations/implications: The strength of presented composite isn’t good and constitutes a further direction of research and development of the material. Practical implications: Although decreased strength properties, the composite with no visible trend of a decrease in the coefficient of thermal expansion with increasing temperature could be used as panels in high-temperature firing processes. Originality/value: New ceramic foundry composite based on a spherical form of aluminium oxide for auxiliary panels in high temperature processes.

20

Microstructure and mechanical properties of CuZn-Al2O3 nanocomposites produced by friction stir processing

Heidarzadeh Akbar, Taghizadeh Babak, Mohammadzadeh Ahad

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 3

494--505

EN

For the first time, ceramic nano particles were incorporated into the brass alloy to produce surface nano composites by friction stir processing. For this aim, Al2O3 particles with an average diameter of 30 nm were inserted into a Cu-37Zn alloy at different tool rotational speeds of 450, 710, and 1120 rpm, multi passes, and a constant traverse speed of 100 mm/min. The microstructures of the processed materials were analyzed using optical and scanning electron microscopes equipped with an energy dispersive spectroscopy. In addition, tensile test was employed to evaluate the mechanical properties. The results showed that the optimum rotational speed was 710 rpm. At lower rotational speeds, Al2O3 particles were agglomerated. On the other hand, at higher rotational speeds, tool was damaged by severe wear. The effect of multi passes showed that one and two passes could not distribute the Al2O3 particles, uniformly. However, three passes resulted in a uniform distribution of the Al2O3 particles inside a bimodal grain structure composed of both 3–5 μm grains and ultra-fine grains (< 1 μm). By using multi-pass friction stir processing, a synergic increase in ultimate tensile strength and elongation was obtained. Moreover, three passes caused superior mechanical properties i.e. ultimate tensile strength of 430 MPa and elongation of 39%. The fracture behavior and strengthening mechanisms are also discussed in details.