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1

Stability investigation of the pcm nanocomposites

Cieśliński Janusz T., Boroń Paulina, Fabrykiewicz Maciej

Acta Mechanica et Automatica

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2023

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Vol. 17, no. 3

381--389

EN

Ensuring the stability is a key issue to be solved for the technical application of nanocomposites. In this work, fatty acid P1801 served as base phase change material (PCM)P1801, and its main ingredients are palmitic acid (58%) and stearic acid (38%). Titania (TiO2) and alumina (Al2O3) with mass concentrations of 1% and 5% were selected as nanoparticles, while polyvinylpyrrolidone (PVP) or oleic acid (OA) with mass concentrations of 5% were tested as surfactants. On the basis of the measured temperature distributions in the sample, which is subject to melting and solidification processes, it was determined which of the tested nanocomposites are stable and which are not. In addition, a thermal test was proposed to assess the stability of the produced nanoPCM, which consists in measuring the temperature distribution versus time according to a precisely given procedure.

2

An experimental investigation of wire breakage and performance optimisation of WEDM process on machining of recycled aluminium alloy metal matrix composite

Kannan P. R., Periasamy K., Pravin P., Vinod Kumaar J. R.

Materials Science Poland

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2022

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Vol. 40, No. 3

12--26

EN

In this research, a novel aluminium metal matrix composite (AMMC) was developed using recycled aluminium alloy as a matrix with 5% alumina as reinforcement. The machining experiments were conducted by varying the input parameters such as voltage (Vs), wire feed rate (Fw), current (Ip), pulse on time (ONT) and pulse off time (OFFT), on wire breakage. The effect of voltage level and wire breakage frequency was analysed. The parameter combinations for machining the slot of size 5 mm width and 10 mm height with high machining rate (MR) and less surface roughness (Ra) were analysed using the Criteria Importance Through Intercriteria Correlation (CRITIC) and simple additive weighting (SAW) methods. The wire breakage frequency is lesser at minimum peak current. The optimal parameter combination for higher MR and lower Ra is found to be at 30 V, 7 mm/min, 30 A, 120 μs (ONT) and 70 μs (OFFT). Analysis of variance (ANOVA) is performed to understand the significant factors affecting the WEDM process. ANOVA results predict that wire feed rate and voltage contribute 47.82% and 21.23%, respectively, to MR; and pulse on time shows a 23.06% influence on surface roughness. Scanning electron microscopy (SEM) was used to ascertain the pattern of wire breakage in WEDM, and based on the results obtained from employing this technique, it is inferred that the erosion and breakage of the wire are not instantaneous and that a cone shape is formed on the either portion of the wire.

3

Research Results of a Complex Reagent for Wastewater Purification from Hydrogen Sulfide

Ospanov Kairat, Kuldeyev Erzhan, Kenzhaliyev Bagdaulet, Kuldeyeva Elmira

Journal of Ecological Engineering

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2022

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Vol. 23, nr 5

278--285

EN

This article presents the results of research intended to obtain a complex alumina-iron reagent based on natural diatomite and industrial products of alumina production for wastewater purification from hydrogen sulfide. The material composition of the obtained samples using X-ray diffraction analysis was determined. The results of interaction research in the NaFeO2 – H2S – H2O system at 25°С are given. The results of research on wastewater purification from hydrogen sulfide in Almaty city with the use of ferric sulfate, ferric chloride, sodium ferrite and a complex reagent containing iron at the content of 5.1 mg/l H2S in the initial sample of wastewater were presented.

4

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.

5

Effect of Silica Fume and Alumina Addition on the Mechanical and Microstructure of Fly Ash Geopolymer Concrete

Min Fong Sue, Yong Heah Cheng, Ming Liew Yun, Al Bakri Abdullah Mohd Mustafa, Razi Hasniyati Md, Low Foo Wah, Ng Hui-Teng, Ng Yong-Sing

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 1

197--202

EN

This paper discussed the effect of the addition of silica fume (2 wt.% and 4 wt.%) and alumina (2 wt.% and 4 wt.%) on the properties of fly ash geopolymer concrete. The fly ash geopolymer concrete achieved the highest 28-day compressive strength with 2 wt.% of silica fume (39 MPa) and 4 wt.% of alumina (41 MPa). The addition of 2 wt.% of silica fume increased the compressive strength by 105% with respect to the reference geopolymer (without additive). On the other hand, the compressive strength surged by 115% with 4 wt.% of alumina compared to the reference geopolymer. The addition of additives improved the compactness of the geopolymer matrix according to the morphology analysis.

6

The Use of Phosphate Binder for Ablation Casting of AlSi7Mg Modified TiB Alloy

Puzio Sabina, Kamińska J., Major-Gabryś K., Angrecki M.

Archives of Foundry Engineering

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2022

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Vol. 22, iss. 1

62--68

EN

The possibilities of using an inorganic phosphate binder for the ablation casting technology are discussed in this paper. This kind of binder was selected for the process due to its inorganic character and water-solubility. Test castings were made in the sand mixture containing this binder. Each time during the pouring liquid alloy into the molds and solidification process of castings, the temperature in the mold was examined. Then the properties of the obtained castings were compared to the properties of the castings solidifying at ambient temperature in similar sand and metal molds. Post-process materials were also examined - quartz matrix and water. It has been demonstrated that ablation casting technology promotes refining of the microstructure, and thus upgrades the mechanical properties of castings (Rm was raised about approx. 20%). Properties of these castings are comparable to the castings poured in metal moulds. However, the post-process water does not meet the requirements of ecology, which significantly reduces the possibility of its cheap disposal.

7

Investigating the effects of alumina nanoparticles on the impact resistance of polycarbonate nano-composites

Alavi Nia Ali, Amirchakhmaghi Saeed

Archive of Mechanical Engineering

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2022

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LXIX, nr 3

431--454

EN

In this project, two types of treated and untreated alumina nanoparticles with different weight percentages (wt%) of 0.5, 1 and 3% were mixed with polycarbonate matrix; then, the impact ballistic properties of the nano-composite targets made from them were investigated. Three types of projectile noses -cylindrical, hemispherical, and conical, each with the same mass of 5.88 gr – were used in the ballistic tests. The results highlighted that ballistic limit velocities were improved by increasing the percentage of alumina nanoparticles and the treatment process; changing the projectile’s nose geometry from conical to blunt nose increases the ballistic limit velocity, and ultimately, by increasing the initial velocity of conical and hemispherical nosed projectiles, the failure mechanism of the targets changed from dishing to petalling; whereas for the cylindrical projectile, the failure mode was always plugging.

8

New materials based on hyaluronic acid and egg albumin mixture

Gadomska Magdalena, Musiał Katarzyna, Sionkowska Alina

Engineering of Biomaterials

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2021

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Vol. 24, no. 160

15--21

EN

In this work, new materials based on the mixture of hyaluronic acid and albumin from chicken eggs have been studied. Tests were carried out to determine the molecular weight of the tested hyaluronic acids. The properties of hyaluronic acid were investigated and significant differences were found in the mechanical properties of the tested compound, depending on its molecular weight. It was found that egg albumin can be combined with hyaluronic acid and thin films can be obtained. Spectrometric tests were performed both for pure compounds and for mixtures of hyaluronic acid with chicken egg albumin. IR spectroscopy showed that interactions between hyaluronic acid and egg albumin are mainly by hydrogen bonds, as the shifts in the main bands in IR spectra were observed. The addition of egg albumin to hyaluronic acid leads to the decrease of its mechanical properties. The deterioration of the mechanical properties of polymer films from HA-albumin mixtures may be due to interactions between compounds which were shown in the IR spectra. The thin films based on hyaluronic acid and egg albumin blend can be used as adhesive materials in biomedicine and cosmetics. Both biopolymers are biocompatible and biodegradable so we can expect a biocompatible and biodegradable material for potential application as adhesives.

9

Investigation on Mechanical Properties and Microstructures of Aluminum Hybrid Composites Reinforced with Al2O3/GNPs Binary Particles

Şenel M. Can, Gürbüz M.

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 1

97--106

EN

Nowadays, aluminum-based composites have been produced by pure alumina (Al2O3) or pure graphene nanoplatelets (GNPs) in aluminum matrix because of the high compressive strength of alumina and the solid lubricant properties of graphene. However, there are no studies on the influence of both alumina and graphene reinforced aluminum composites. In this study, Al-Al2O3 and Al-Al2O3-GNPs composites were reinforced with pure alumina (between 0 and 30 wt.%), pure graphene (0, 0.1, 0.3, 0.5 wt.%), and their hybrid forms (Al2O3-GNPs) by the powder metallurgy method. This method involved ultrasonic dispensing, mixing, filtering, drying, pressing, and sintering processes. From the test results, the micro Vickers hardness of pure aluminum (28.2±1 HV) improved to 51.5±0.8 HV (Al-30Al2O3) and 63.1±1 HV (Al-30Al2O3-0.1GNPs). Similarly, the ultimate compressive strength (UCS) enhanced from 92.4±4 MPa (pure aluminum) to 165±4.5 MPa (Al-30Al2O3) and 188±5 MPa (Al-30Al2O3-0.1GNPs), respectively. In conclusion, the Vickers hardness and ultimate compressive strength of aluminum hybrid composites improved up to 0.1 wt.% graphene content. After 0.1 wt.% graphene content, these mechanical properties decreased because of the clumping of graphene nanoparticles.

10

The abrasive wear susceptibility of innovative ATZ type composites produced by sintering mix of zirconia powders with different chemical composition

Grabowy Marek, Wojteczko Kamil, Wojteczko Agnieszka, Dębiński Piotr, Almansour Sana Ahmad, Minh Le Huy, Bućko Mirosław M., Pędzich Zbigniew

Composites Theory and Practice

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2020

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R. 20, nr 1

11--16

EN

Composites based on tetragonal zirconia polycrystals modified with corundum inclusions ATZ (alumina toughened zirconia), are one of the basic and more commonly used ceramic structural materials. They are used especially willingly as parts of devices and machinery working in both dry and wet wear conditions in the presence of hard abrasive particles intensifying wear processes. The mechanical properties of such composites, strength and fracture toughness mainly, strongly depend on their chemical and phase compositions as well as microstructure. The aim of the present work was to investigate an innovative type of ATZ material composed of a mixture of two ZrO2 powders with different chemical composition and a small addition (2.3 vol.%) of nanometric corundum powder. The proper composite materials additionally contained 10 or 20 vol.% commercially available corundum particles. Tests were carried out on the mentioned materials for abrasive wear susceptibility according to the ASTM Dry Sand Test and ASTM Miller Test, using silicon carbide particles as the abrasive medium. As a reference materials, typical TZP (tetragonal zirconia polycrystals) material prepared using commercial powder and ZTA (zirconia toughened alumina) material containing 5 vol.% zirconia dispersed in an alumina matrix were used. The obtained results allowed the usability of the individual composite materials to be verified under various operating conditions.

PL

Kompozyty na osnowie tetragonalnego dwutlenku cyrkonu, modyfikowane wtrąceniami korundowymi (alumina toughened zirconia, ATZ), są jednym z podstawowych i częściej stosowanych ceramicznych tworzyw konstrukcyjnych. Szczególnie chętnie są stosowane jako elementy maszyn i urządzeń pracujące w warunkach tarcia suchego lub w obecności wody, często w obecności twardych cząstek intensyfikujących procesy zużycia. Właściwości mechaniczne tego typu kompozytów, głównie wytrzymałość i odporność na kruche pękanie, silnie zależą od ich składu chemicznego, fazowego i mikrostruktury. Celem niniejszej pracy było zbadanie innowacyjnego typu kompozytów ATZ, w którym jako osnowę zastosowano mieszaninę dwóch proszków ZrO2 o różnym składzie chemicznym z niewielkim (2,3% obj.) dodatkiem nanometrycznego proszku korundu. Właściwe materiały kompozytowe zawierały ponadto komercyjnie dostępne ziarna korundu w ilości 10 lub 20% obj. Wykonano dla tych materiałów testy podatności na zużycie ścierne luźnym ścierniwem węglika krzemu według norm ASTM - Dry Sand Test i Miller Test. Jako materiałów odniesienia użyto typowego materiału TZP (tetragonal zirconia polycrystals) uzyskanego z komercyjnego proszku oraz materiału typu ZTA (zirconia toughened alumina). Otrzymane wyniki pozwoliły zweryfikować użyteczność poszczególnych typów kompozytu w różnych warunkach pracy.

11

Modified bentonite-derived materials as catalystsfor selective catalytic reduction of nitrogen oxides

Szymaszek Agnieszka, Kubeł Maciej, Samojeden Bogdan, Motak Monika

Chemical and Process Engineering

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2020

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Vol. 41, nr 1

13–-24

EN

In the last few years, cationic layered clays, including bentonites have been investigated as potentialcatalysts for SCR DeNOxsystems. In this work, bentonite as the representative of layered clays wasmodified in order to obtain an alternative, low-cost NH3–SCR catalyst. Samples of raw clay wereactivated with HCl or HNO3, treated with C2H2O4and subsequently pillared with alumina by the ion-exchange. Afterwards, the modified materials were impregnated with iron and copper. The obtainedcatalysts were characterized by XRD and FT-IR. SCR catalytic tests carried out over analyzed samplesindicated the conversion of NO of approximately 90% for the most active sample. The type of acidused for modification and the type of active phase strongly influenced the catalytic properties of theanalyzed materials.

12

The role of hydrogen gas buble in hydrophobic properties in mixed micro layer (Al2O3+Mg)

Subagyo R., Wardana I. N. G., Widodo A., Siswanto E.

Archives of Materials Science and Engineering

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2020

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Vol. 105, nr 1

5--16

EN

Purpose: To find out more about the role of hydrogen gas bubbles in improving the hydrophobic nature of a layer, especially in the layers of microparticles Alumina (Al2O3) with Magnesium (Mg). Design/methodology/approach: The method used is an experimental method by first conducting the SEM-Edx test, testing the content of the elements in the waxy layer and observing the topographic shape on the surface of the taro leaves. Then prepare a mixture of Alumina micro particles with Magnesium to investigate the hydrophobicity of the taro leaves. The mixed presentations between Alumina and Magnesium are: (0, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100%). Findings: The results of this study found three conditions of the Alumina and Magnesium mix layer when in contact with a droplet, namely: Hydrophobic conditions occur when the surface structure of the rough mixed micro layer forms micro crevices, then bubbles of hydrogen gas fill it to form trapped gases. When droplets come in contact with the surface of the mixed layer the effect of the gas being trapped is very effective at creating hydrophobic properties. While the transition conditions occur when more and more hydrogen gas bubbles along with the increasing percentage of Mg and the opposite occurs in micro particle fissures. Bubbles fill the micro-gap space fully so that the tops of the micro particles are covered by bubbles. This causes the droplet surface tension to weaken, so the droplet contact angle decreases. Furthermore, hydrophilic conditions occur when the micro gap is getting narrower as the percentage of Mg increases and the formation of hydrogen gas bubbles increases. The high level of bubble density in the micro gap closes the peaks of the micro particles, which results in the surface tension of the droplet getting weaker. In this weak surface tension condition, the hydrogen bubble can break through the droplet surface tension and change its hydrophobic nature to hydrophilic. Research limitations/implications: This research is limited to the hydrophobicity of Alumina and Magnesium materials, mainly to investigate the role of hydrogen gas in supporting the hydrophobic nature of taro leaves (Colocasia esculenta). Practical implications: The practical implication in this study is the use of hydrophobic membranes which are widely applied to filtration. Originality/value: Discovered the composition of a membrane mixture of Alumina (Al2O3) and Magnesium (Mg) to create hydrophilic and hydrophobic conditions.

13

Tribological Properties of Al2O3/ZrO2 Sintered Ceramics

Wiązania Grzegorz, Kot Marcin, Wojteczko Agnieszka, Pędzich Zbigniew

Tribologia

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2019

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nr 1

67--72

EN

The paper presents mechanical and tribological properties of Al2O3/ZrO2 composite sinters with different proportions of Al2O3 and ZrO2 phases. These materials are commonly used in dry friction contact due to relatively low manufacturing costs of even complex shapes of products and the possibility of working at elevated temperatures. The tests were carried out by the ball-on-disc method at temperatures of 20, 150, 300, and 500°C. A ball made of Al2O3 was used as a counterpart. The results were compared with the following sintered mono-phase materials: Al2O3 (alumina) and tetragonal yttria-stabilized ZrO2 polycrystallines (Y-TZP). The tests showed the significantly better properties of composite materials.

PL

W pracy przedstawiono właściwości mechaniczne i tribologiczne spieków kompozytowych Al2O3/ZrO2 o różnej proporcji faz Al2O3 i ZrO2. Są to materiały chętnie stosowane w węzłach tarcia suchego ze względu na relatywnie niskie koszty wytwarzania nawet skomplikowanych kształtów wyrobów i możliwość pracy w podwyższonych temperaturach. Testy przeprowadzono na stanowisku z węzłem tarcia ball-on-disc w temperaturach 20, 150, 300 i 500°C, jako przeciwpróbkę zastosowano kulkę wykonaną z Al2O3. Wyniki badań porównywano z wynikami badań spieków wytwarzanych z materiałów jednofazowych: α- Al2O3 (korund) i tetragonalnych polikryształów ZrO2 stabilizowanych tlenkiem itru (tzw. Y-TZP). Badania wykazały znacząco lepsze własności materiałów kompozytowych.

14

Production of cement composites using alumina-lignin hybrid materials admixture

Klapiszewska Izabela, Ślosarczyk Agnieszka, Klapiszewski Łukasz, Jesionowski Teofil

Physicochemical Problems of Mineral Processing

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2019

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Vol. 55, iss. 6

1401--1412

EN

In the framework of this study, Al2O3-lignin hybrid materials differing in terms of the weight ratio of the inorganic and organic components were designed and obtained. The method of mechanical grinding of ingredients with simultaneous mixing using a mortar grinder and a high-performance ball mill was used in order to obtain the above-mentioned systems. The effectiveness of obtaining alumina- lignin materials was confirmed using Fourier transform infrared spectroscopy (FTIR) and, indirectly, by the colorimetric analysis. FTIR analysis allowed to confirm that hydrogen bonds formed between the components and classify the resulting systems as Ist class hybrid materials. In the course of the conducted research, the relatively high thermal stability of the hybrid materials was also confirmed and the dispersion and morphological character (SEM) of the obtained systems was determined. Favourable physicochemical and microstructural evaluation allowed to qualify the alumina-lignin hybrid systems as functional admixtures for cement mortars. As part of the tests, it was confirmed that the presence of lignin in the cement composites contributes to the increase of the plasticity of the mixture. In turn, the inorganic component allowed to preserve (and, in case of selected systems, improve) the mechanical properties of the final composites. The most favourable results of application tests were obtained for alumina-lignin hybrid systems with a weight ratios equal to 5:1 and 2:1. The analysis of these systems indicated that there is a clear improvement of mechanical properties, whit a simultaneous enhancement of the plasticity of the mixture in comparison to the reference sample.

15

Experimental evaluation of Al-Zn-Al2O3 composite on piston analysis by CAE tools

Krishnan B. Radha, Ramesh M.

Mechanics and Mechanical Engineering

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2019

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Vol. 23, nr 1

212--217

EN

Today’s automotive designers and material specialists regard lighter vehicles for less fuel consumption (economy and ecology) and higher safety to passengers. Metal matrix composites have been a large area of interest. Aluminium composite is potentially applied in automotive and aerospace industries, because it has a superior strength to weight ratio and is a light weight metal with high temperature resistance. Composites containing hard oxides and ceramics (such as alumina) are preferred for high wear resistance along with increased hardness. In thiswork, alumina and zinc are reinforced in Al-LM25 alloy through stir casting process, where alumina is varied 6% and 12% in Al-5%Zn. Various mechanical analyses were conducted and the effect of wear with different percentage of alumina reinforcement was studied. The resulting properties are imported in a piston, modelled using solidworks, and analysed in ANSYS work bench. Imparting this new material for pistons could introduce deep design and improvements in engine operation of a vehicle.

16

Właściwości mechaniczne kompozytów typu ATZ otrzymanych w procesie spiekania mieszaniny proszków dwutlenku cyrkonu o różnym składzie chemicznym

Grabowy Marek, Maciewicz Karolina, Łuszcz Maciej, Pędzich Zbigniew, Bućko Mirosław M.

Materiały Ceramiczne

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2019

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T. 71, nr 3

286--294

PL

Kompozyty na osnowie tetragonalnego dwutlenku cyrkonu, zawierające wtrącenia korundowe (alumina toughened zirconia, ATZ), są jednym z podstawowych i częściej stosowanych ceramicznych tworzyw konstrukcyjnych. Właściwości mechaniczne tego typu kompozytów, głównie wytrzymałość i odporność na kruche pękanie, silnie zależą od ich składu chemicznego, fazowego i mikrostruktury. Celem niniejszej pracy było otrzymanie kompozytów ATZ w procesie spiekania mieszaniny dwóch proszków ZrO2 o różnym składzie chemicznym z niewielkim (1.5 % mas.) dodatkiem nanometrycznego proszku korundu, a także określenie ich mikrostruktury i podstawowych właściwości mechanicznych. Użyto nanometrycznego proszku czystego dwutlenku cyrkonu i proszku zawierającego 4% mol. tlenku itru, a ich ilości w mieszaninie z nanokorundem dobrano tak, aby końcowy produkt miał nominalnie 3% mol. Y2O3. 1,5% mas. nanometrycznego tlenku glinu Do takiej mieszaniny proszków dodano 10% lub 20% obj. proszku submikronowego korundu po czym wypraski spiekano w 1450 °C przez 2 h. Tak otrzymany materiał cechował się wyższą wartością współczynnika krytycznej intensywności naprężeń, lecz niższą wytrzymałością na zginanie w stosunku do spieku otrzymanego w tych samych warunkach z jednofazowego proszku. Obecność ziaren tlenku glinu w każdym przypadku podnosiła zarówno odporność na kruche pękanie, jak i wytrzymałość.

EN

Composites based on tetragonal zirconia, containing corundum inclusions (alumina toughened zirconia, ATZ), are one of the basic and more commonly used ceramic structural materials. The mechanical properties of this type of composites, mainly strength and fracture toughness, strongly depend on their chemical and phase composition as well as their microstructure. The purpose of this work was to obtain ATZ composites in the sintering process of two ZrO2 powders with different chemical composition with a small (1.5 wt%) addition of nanometric corundum powder, as well as to determine their microstructure and basic mechanical properties. Nanometric powders of pure zirconia and zirconia containing 4 mol% yttrium oxide were used, and their amounts in the mixture with nanocorundum were selected so that the final product had a nominal 3 mol% Y2O3. To this powder mixture, 10% or 20% by volume of submicron corundum powder was added, after which the compacts were sintered at 1450 °C for 2 h. The material obtained in this way was characterized by a higher value of the critical stress intensity factor, but a lower bending strength in relation to the sintered body obtained under the same conditions from a single-phase powder. The presence of alumina grains in each case increased both fracture toughness and strength.

17

Al2O3-Cu-Mo hybrid composites : fabrication, microstructure, properties

Zygmuntowicz Justyna, Łukasiak Agata, Piotrkiewicz Paulina, Kaszuwara Waldemar

Composites Theory and Practice

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2019

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R. 19, nr 2

43--49

EN

The work investigated the influence of the share of metallic components on the microstructure and selected properties of Al2O3-Cu-Mo composites. Commercial powders were used to produce the composite samples. The composites were obtained by the slip casting method. Three series of composites with a different volumetric composition of metals in the total content of the metallic phase were obtained: Series I - contained 7.5 vol.% Cu - 7.5 vol.% Mo, Series II - contained 10 vol.% Mo - 5 vol.% Cu and Series III - contained 12 vol.% Mo - 3 vol.% Cu. All the series contained 15 vol.% metal particles with respect to the total solid phases. Rheological analysis showed that the slurries used to make the composites were shear thinning fluids. The X-ray analysis showed that regardless of the volume content of copper in the suspensions used to form the composite, all the composites after sintering were characterized by the presence of three phases: Al2O3, Cu and Mo. It was found that the microstructure in all the series is characterized by homogeneous distribution of the metal particles. All the samples were characterized by high porosity, which resulted in their low relative density. The volume fractions of molybdenum and copper in the composite slightly do affect the hardness and fracture toughness of the composite. The obtained hardness results indicate that increasing the molybdenum content in the composites causes an insignificant increase in the hardness of the samples.

PL

W pracy zbadano wpływ udziału komponentów metalicznych na mikrostrukturę i wybrane właściwości kompozytów Al2O3-Cu-Mo. Do wykonania próbek użyto komercyjnie dostępnych proszków: Al2O3, Cu i Mo. Kompozyty otrzymano metodą odlewania z gęstwy. Wytworzono trzy serie kompozytów o różnym składzie objętościowym metali w całkowitej zawartości fazy metalicznej: Seria I zawierała 7,5% obj. Cu - 7,5% obj. Mo, Seria II zawierała 10% obj. Mo - 5% obj. Cu i Seria III - zawierała 12% obj. Mo - 3% obj. Cu. Wszystkie serie zawierały 15% obj. cząstek metalu w odniesieniu do całkowitej fazy stałej. Badania reologiczne wykazały, że masy lejne użyte do wytwarzania kompozytów były cieczami newtonowskimi rozrzedzanymi ścinaniem. Badanie składu fazowego wykazało, iż niezależnie od zawartości objętościowej miedzi w masie lejnej użytej do wytworzenia kompozytu wszystkie kompozyty po spiekaniu cechowała obecność trzech faz: Al2O3, Cu i Mo. Stwierdzono, że mikrostruktura we wszystkich seriach charakteryzuje się jednorodnym rozkładem cząstek metalu. Wszystkie próbki charakteryzowała wysoka porowatość, co skutkowało ich niskim zagęszczeniem. Udział objętościowy molibdenu i miedzi w kompozycie wpłynął na jego twardość i odporność na kruche pękanie. Uzyskane wyniki twardości wskazują, że zwiększenie zawartości molibdenu powoduje niewielki wzrost twardości próbek.

18

Tailored Al2O3-Al2TiO5-TiO2 Composite Ceramics from different Titanium Precursors

Dittert B., Wiessner M., Angerer P., Lackner J. M., Leichtfried H.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 4

1277--1286

EN

Al2 O3 -Al2 TiO5 -TiO2 composites can be obtained by the infiltration of molecular titanium precursors into presintered α-Al2 O3 (corundum) cylinders. Two titanium tetra alkoxides, and two dialkoxy titanium bis (acetylacetonates) serve as precursors for TiO2 (rutile) and Al2 TiO5 (tialite). The precursors were infiltrated as ethanolic solutions. After sintering at 1550, 1600, and 1650°C, the prepared ceramics’ properties were investigated by SEM, in-situ HT-XRD, and conventional XRD. Titanium tetraisopropoxide leads to the highest content of Al2 TiO5 in the composite. The more reactive the precursor, considering the Al2 O3 /precursor interface, the lower and more anisotropic the grain growth, the more homogeneous is the TiO2 contribution and the higher is the content of Al2 TiO5 . Raising the sintering temperature causes an increase of the crystalline Al2 TiO5 content as well as of the grain growth. Moreover, the reactivity of the precursor molecule influences the Ti/(Al+Ti) ratio in the obtained tialite phase.

19

Technologia U-FAST w wytwarzaniu przeświecalnej ceramiki Al2O3

Jach K., Rosiński M.

Szkło i Ceramika

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2018

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R. 69, nr 6

21--24

PL

Przeświecalna ceramika Al2O3 jest pożądanym materiałem z uwagi na swoje właściwości porównywalne z szafirem. Charakteryzuje się wysoką odpornością na zużycie, wysoką stabilnością chemiczną i doskonałą odpornością na korozję. Głównymi obszarami jej zastosowań są: wysokotemperaturowe wizjery, drobne elementy opancerzenia, detektory podczerwieni oraz koperty emiterów podczerwieni. Do wytwarzania transparentnej ceramiki stosowane są techniki HP, SPS i HIP. W niniejszej pracy materiały otrzymano z zastosowaniem technologii U-FAST (ang. Upgraded-Field Assisted Sintering Technology), jednego z najnowocześniejszych rozwiązań na rynku urządzeń do spiekania. Jest to efektywna i energooszczędna technologia przeznaczona do konsolidacji materiałów proszkowych, w tym nanokrystalicznych. Procesy spiekania przeprowadzono z wykorzystaniem handlowego proszku tlenku glinu, bez użycia dodatków. Zbadano wpływ parametrów procesu na mikrostrukturę i stopień zagęszczenia uzyskanych spieków, jak również na transmisję w zakresie światła widzialnego.

EN

Transparent Al2O3 ceramics arouses of great interest due to its properties comparable to sapphire. Alumina is characterized by high wear-resistance, high chemical stability, excellent corrosion resistance. The main areas of its applications are high-temperature light transmitting materials, small armor protection, infrared detectors, IR emitters envelopes. For the production of transparent ceramics, HP and SPS and HIP techniques are used. In this paper, the materials were made using the U-FAST technology (Upgraded-Field Assisted Sintering Technology), one of the most modern solutions on the market of sintering devices. It is an effective and energy-saving technology dedicated to consolidation of powder materials, including nanocrystalline materials. The sintering processes were carried out using commercial alumina powder without the use of additives. The influence of sintering parameters on the microstructure and density of the obtained sinters, as well as on transmittance in visible range were studied.

20

Przeświecalna ceramika z tlenku glinu wytworzona w technologii U-FAST

Jach K., Rosiński M.

Materiały Ceramiczne

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2018

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T. 70, nr 4

293--300

PL

Celem opisanych badań było wytworzenie przeświecalnej w zakresie bliskiej podczerwieni ceramiki tlenku glinu z zastosowaniem technologii U-FAST, a także zbadanie wpływu parametrów procesu na mikrostrukturę i stopień zagęszczenia uzyskanych spieków. W temperaturze 1200 °C uzyskano spiek o stopniu zagęszczenia blisko 100% gęstości teoretycznej, który charakteryzował się transmitancją wynoszącą 83%. Nie zastosowano dodatków ułatwiających spiekanie.

EN

The aim of the work was to fabricate a transparent alumina ceramics in the near infrared range by U-FAST technology, and to determine the influence of sintering parameters on the microstructure and density of the obtained sinters. Samples with a density close to 100% of theoretical density and a transmittance of 83% were obtained at 1200 °C. No additives to facilitate sintering process were used.