Symposium : M
Nanosurface layers on metals and ceramics
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| 14:00 | Termodynamics and growth kinetics and structure of silicide layers on tungsten and molibdenum surface during the contact with silicon binary melts Authors : Skorokhod V.V., Titov V.P.,Filipov N.I. Frantsevich Institute for Problems of Materials sciences of National Academy of Sciences of Ukraine Resume : The suitability of tungsten and molybdenum as a heat-resistant materials to be used at high temperatures is limited because of there low oxidation resistance. Therefore, in order to protect these metals from oxidation, silicide protective coatings are deposited. The silicide coatings could be made by layer deposition from Si-containing melts.
The present work contains the results of experimental investigations of molybdenum solubility in copper-silicon melts in the concentration region 20-40 %(аt.)Si. The kinetics of the growth of the Mo5Si3 and MoSi2 silicide layers from the copper-silicon-molybdenum melt was investigated. The experiments were carried out in a vacuum of (2.-.4)x10-3 Pа at 1200 0С.
It has been established that the interaction of Mo with Cu-Si-Mo melts at a Si content of (18.3–28.5) %(аt.) produced the Mo5Si3 phase only. The time dependence of Mo5Si3 layer growth fairly obeys the Tamman law: l2=2kt, where l, t and k are the thickness the layer, time and rate constant of its growth, respectively.
Таble 1. Growth rate constants of the Mo5Si3 layer (k) from Cu-Si-Mo melts
Content Si Silicon k Mo-Si x 10 -13
% mass atomic fraction activity, аSi м 2 с -1
9 0.183 0,0100 0,27
12 0.236 0,0218 1,13
15 0.285 0,0414 2,3
20 0.361 0,0952 7,7
Hence, the dependence of the rate constant of the Mo5Si3 phase growth on the silicon activity in the melt is determined by the expression kMo-SI = (-0.3806)+ (65.191)аSi (Table 1). It makes possible to establish the composition of the three-phase equilibrium Mo/Mo5Si3/ (Cu-Si ) melt: XSi=0.147; XMo=7.86.10-3,
At a silicon content in the melt of 20%(mass), the (29.8±2.9) μm thick Mo5Si3 phase layer is formed on the molybdenum boundary and the (25.7 ±2.8) μm thick MoSi2 phase layer is formed on the melt boundary. When the Si content reaches 30%(mass), a marked growth of MoSi2 phase layer to 57 μm and a decreasing the thickness of Mo5Si3 layer to 5 μm are observed. At 35%(mass)Si, only the MoSi2 phase is formed at the interface.
Then studying the phase composition and the kinetics of growth of silicide layers during the interaction of W with Cu-Si-W melts were carried out. It has been established that the interaction of W with Cu-Si-W melts at the investigated contents produced the WSi2 phase only. The values of growth rate constants of the WSi2 layers on W specimens (k) are given in Table 2.
Таble 2. Growth rate constants of the WSi2 layer (k) from Cu-Si-W melts
Content Si Silicon k W-Si x10 13 ,
% mass atomic fraction activity, аSi м 2 с -1
12 0.236 0.019 0.14
15 0.285 0.044 1.7
20 0.361 0.109 20
25 0.430 0.196 45
40 0.601 0.497 190
The techniques of silicide layers preparation on Mo and W surfaces by precipitation from (Cu-Si) melts had been developed. | 0 |
| 14:30 | Growth Mechanism model for Single Layer and Few Layer Graphene using CVD on Copper Substrates Authors : Abhishek Rishabh Indian Institute of Technology Kanpur India Naomi Nandkumar National University of Singapore Resume : Graphene is one of the most intriguing material in contemporary times. Exfoliated graphene has limitation of small sizes whereas large area graphene has very important effects in FETs. Recently large area graphene growth technique is developed using CVD on Copper substrates. Isotopic Labeling is used in this approach to explain the surface adsorption growth mechanism. This model presents the growth mechanism of single layer graphene and few layer graphene which finally would be related to Langmuir and BET isotherms, which would lead to a mathematical understanding of the growth mechanism. | 0 |
| 14:50 | Statistical investigation of the antiferromagnetic domains structure in hematite films. Authors : Antoine Barbier (1), Odile Bezencenet (1,3), Daniel Bonamy (1), Rachid Belkhou (2), Philippe Ohresser (2). (1) CEA-Saclay, IRAMIS/SPCSI, France (2) Synchrotron SOLEIL, France (3) THALES, France Resume : The investigation and observation of antiferromagnetic domains is challenging because antiferromagnets do not carry any net external magnetic dipole moment. Their observation has only been made possible recently by photoelectrons microscopies. Thus, the detailed description and manipulation of the microstructure of antiferromagnetic domains, domain shape and size distribution still remain poorly described and understood. We have investigated the antiferromagnetic domain structure of epitaxial Fe2O3/Pt(111) layers in the an extended thickness range 2 – 30 nm using X-PEEM imaging. The experiments were performed at the Swiss Light Source (SLS) taking advantage of the large L-edge dichroic effects related to the magnetic domain structure in ferromagnetic and antiferromagnetic transition metal based layers. From the statistical image analysis we demonstrate that the domain structure remains statistically invariant with thickness. Moreover the antiferromagnetic domain structure of the thin films appears as inherited from the magnetic domain structure of the ferri-magnetic precursor layer that exists at small layer thicknesses, before the antiferromagnetic spin ordering sets in. Modifying the magnetic domain structure of the ferrimagnetic precursor layer appears as a possible way to modify the magnetic domain structure of antiferromagnetic layers. | 0 |
| 15:30 | Coffee break | |
| 17:30 | Electronic transport in unintentionally doped In-rich GaxIn1-xN Authors : ? D?z1, E.M. Kendirlik2, M. Yılmaz3, A. Erol1, M.? Arıkan1, B. Uluğ2, A. Uluğ2, , N. Balkan Resume : We present Hall mobility results of In-rich GaxIn1-xN samples with 22% and 48% Ga concentrations. Hall Effect measurements are carried out at temperatures between 77K and room temperature. Hall mobility shows very weak temperature dependence with slightly increase towards higher temperatures for both samples and higher Ga concentration cause a decrease at electron mobility. The mobility values at low temperature are found as 90cm2/Vs and 160cm2/Vs for the samples Ga0.48In0.52N and Ga0.22In0.78N respectively. Carrier concentration tends to slightly increase with increasing temperature for the sample with 48% Ga, on contrary decreases with temperature for the sample with 22% Ga. The temperature dependent mobility behaviour is discussed using an analytical model that accounts for the most important scattering mechanisms. | 1M 0 |
| 17:30 | Tíĺ influence of alloying elements concentration on the value of internal stresses in carbon coatings Authors : A.V. Rahachou, D.G. Piliptsov, N.N. Fedosenko R.V. Bekarevich, A.S. Rudenkov Resume : The results of the research into mechanical properties of carbon coatings deposited with the pulsed cathodic arc plasma have been presented in this article. There has been shown that the highest level of internal stresses is characteristic for the coatings generated by the pulsed cathodic-arc sputtering method. The alloying DLC by metals allows to diminish the value of internal stresses compared to the alloying by nitrogen. The coatings are characterized by the internal tensile stresses in the range from 40 to 140 ĚPŕ, which is the negative factor leading to the destruction of the adhesive interaction of the coating-substrate system. Internal stresses diminish with the implantation of copper. It should be kept in mind that the diminishing of internal stresses often relates to the diminishing of hardness and the module of elasticity of the material being coated. | 2M 0 |
| 17:30 | Formation of Nano-Relief of the Gold Films Surface by Thermal Evaporation on the Surface of Single Crystal Si (111) Authors : V. Karbivskyy, A. Shpak, V.Vishnjak, N. Kurgan G.V. Kurdyumov Institute for Metal Physics NAS of Ukraine, 36 Vernadsky blvd., Kiev, 03142 Ukraine Resume : Experimental study of the nanostructure characteristics of gold particles, it agglomeration, of conglomerates formation opens up new possibilities in understanding the influence of the size effect on the physico-chemical properties of matter. The process of the formation of surface-nanorelief of gold film thermally evaporated on Si (111) surface (silicon monocrystal surface) was investigated using scanning probe microscopy. Using surface topography images obtained every 1 minute the main stages of morphological transformation were registered.
At the initial stage Au nanocrystal formation has a fractal nature. The growth mechanism consist in nanoparticle conglomerate formation followed by their transformation to ellipsoidal particles and nanocrystal formation. The next transformation stage is characterized with crystal plane formation. The revealed features of nanorelief transformation are associated with size effect and different state of aggregation of gold nanoclusters namely solid and liquid states.
Au nanoparticle agglomeration during thermal evaporation and after “wet” chemical synthesis shows the identical nanorelief pattern with the formation of clusters consisting of several nanoparticles. | 3M 0 |
| 17:30 | Structure and properties of chromium-nitrogen layers produced on nickel superalloy Inconel 718 by PACVD method Authors : Edyta Kosieniak1, Ryszard Sitek1, Joanna Zdunek1, Krzysztof Sikorski1, Krzysztof J. Kurzydłowski1 1) Wydział Inżynierii Materiałowej, Politechnika Warszawska, ul. Wołoska 141, 02-507 Warszawa Resume : Microstructure and properties of chromium-nitrogen surface layers produced on Inconel 718 Ni-base superalloy by Plasma Activated Chemical Vapour Deposition (PACVD) method were analyzed using light (LM) and scanning electron (SEM) microscopy. The surface topography of the samples was characterized using VEECO scanning profiler and the phase composition by X-ray diffraction (XRD). XRD was also used to determine the level of residual stresses in the initial state and after PACVD treatment. The chemical composition of each phase was analyzed by X-ray microanalyses using SEM equipped with EDS spectrometer. The size, shape and volume fraction of g’-phase precipitates has been examined quantitatively using stereological methods. The hardness and microhardness of the layers were measured by the Vickers method and their adhesion to the substrate was determined. The correlations between the microstructure of the layers and their properties are discussed. | 4M 0 |
| 17:30 | INVESTIGATION OF MORPHOLOGY CHANGES OF METALLIC NANOFILMS DEPOSITED ONTO OXIDE MATERIALS DURING ANNEALING Authors : I.I.Gab, Yu.V.Naidich, B.D.Kostyuk, T.V.Stetsyuk, D.I.Kurkova, S.V.Dukarov, A.P.Kryshtal, O.S.Lytvyn Resume : This work is devoted for investigation of morphology and structure of the following three types of metal nanofilms 100 nm thick deposited onto alumina ceramics and leykosapphire during annealing:
metal films with good ability to wet oxides (Ti, Zr, Hf, Nb);
metal films with satisfactory ability to wet oxides (Ag, Ni);
metal films with no ability to wet oxides (Cr, W, Ta, Pd, Pt).
All films have been deposited onto well polished surfaces of oxide materials by electron beam spraying. Annealing of films was carried out both in vacuum and on air up to high temperatures (1400 – 1600 C).
Obtained films were studied means of atomic-force microscope AFM_N.SCA and scanning microscope JSM-840. All initial metal nanofilms were continuous even at enough high enlargements (x10000). During annealing up to 1500 C, Ti, Zr, Hf and Nb films were continuous, and only during further heating, their dispergation and coagulation was observed. Ag and Ni films start to disintegrate already at 500 – 600 C and, at 800 – 850 C, they have been already completely disintegrated in to separate fragments. Ag films were finally coagulated in to separate round drops. Cr, W, Ta, Pd and Pt films start to fragmentate already at 1100 – 1200 C, and as a result of annealing at 1500 – 1600 C, these fragments became more and more numerous and small. Pd and Pt films turn in to separate rather large drops which have no ability to wet oxide surface.
As, for joining of ceramic materials by brazing or pressure welding, it is desirable for metallized surfaces to be continuous, Ti, Zr, Hf and Nb nanofilms are the most suitable to this purpose, especially if fabrication of high-temperature joints is needed. | 5M 0 |
| 17:30 | CdS films prepared by different techniques: the film properties and its influence on the device parameters of a CdTe/CdS solar cell Authors : G. P?z-Hern?ez1, J. Pantoja Enr?ez3, N.R. Mathews2, David R. Coronado2, X. Mathew2 1 Universidad Polit?ica del Golfo de M?co, C.P. 86600, Para?, Tabasco, M?co. 2 Centro de Investigaci?n Energ? Universidad Nacional Aut?a de M?co, Temixco, Morelos, 62580, M?co. 3 Cuerpo Acad?co Energ?y Sustentabilidad, Universidad Polit?ica de Chiapas, Col. Magisterial, Tuxtla Guti?ez, C.P 29010, Chiapas, M?co. Resume : Cadmium sulfide thin-films of identical thicknesses were prepared by chemical bath deposition (CBD), sputtering and close-spaced sublimation (CSS) techniques. The influence of post-deposition annealing of the CdS films on the opto-electronic properties of the CdTe/CdS devices was studied in detail. The films were characterized for the structural, morphological, optical, and opto-electronic properties. The structural parameters such as lattice constants and crystallite size have been evaluated. The optical properties have been studied in the range of wavelength 250–2500 nm. The band gap values of CdS thin films deposited by different techniques have been estimated and reported. CBD prepared films exhibited high transmittance in the blue region compared with the films prepared by other techniques. The blue transmittance remained unchanged after post deposition treatments at 450 C, which is the temperature range of CdTe/CdS device fabrication. The high blue transmittance of the CBD films is correlated with the increased blue response in the QE of CdTe/CdS devices. | 6M 0 |
| 17:30 | Steel surface and presurface layers characteristics after treatment in transparent condensed medium by Q-switched laser Authors : Victor Janushkevich, Yuriy Nikiforov, Bogdan Kovalyuk, Volodymyr Hlado, Vitalii Mocharskyi Resume : The study deals with the analysis of the wave-like cell structures formation on the ferrite-martensitic steel surface and increasing of hardness and corrosion resistance of near-surface layers in irradiated zones of samples. Irradiation was carried out by Q-switched Nd-laser (GOS-1001) in transparent condensed medium. As a result of a high temperature plasma is formed on the sample surface and laser-induced stress waves propagate deep into the material.
The structure of the irradiated surface and its chemical composition was examined taking advantage of scanning electronic microscopy SEM-106. Corrosion resistance testing was made in 10% nitric acid solution at room temperature.
Two types of laser-irradiated sample surfaces were compared: direct laser ray – proof by cuprum screen and un-proof. The structure of surface and hardness of samples after irradiation were identified.
Investigations testified that the periodic structure formation process is not only due to recoil pressure of steam and plasma but also due to the influence of laser shock wave reflected from the back side of the sample. Expected reasons of appearance of three sufficiently different in the etching rates and micro-hardness areas, located in the depth of 1.5 µm, 8 µm up to 60 µm correspondingly from the surface, are analyzed.
Taking into account micro-hardness depth dependence after irradiation and its distribution on the surface of irradiated and unirradiated samples, the distribution of chemical impurities, the mechanism of corrosion resistance increasing is proposed. It is caused by the cleaning of the grain border in material (steel) due to the specific interaction of weak laser shock with atoms of impurities in the investigated steel. | 7M 0 |
| 17:30 | Modeling of implantation of carbon nanotubes into solid substrate Authors : Yuriy Nikiforov, Mihajlo Nischenko, Bogdan Kovalyuk, Oksana Manyovska Resume : According to the effect of enhanced thermoelectronic emission from aluminum surface implanted with carbon nanotubes it is of interest to model the process of implantation of carbon nanotubes into solid substrate under the influence of Q-switched laser irradiation. An important aspect of the material irradiation by laser in transparent condensed medium (TCM) is the formation of shock waves. Implantation of carbon nanotubes into the aluminum matrix under such experimental conditions was studied by calculating of the temperature field evolution in the specimen subjected to laser treatment, using graphical, analytical and numerical approaches. Main parameters of the model include shape of the energy source, energy redistribution between TCM and the sample under irradiation, and duration of the laser pulse. Both triangular and rectangular pulses were considered. Plasma formed during laser irradiation was used as the energy source on the last stage of modelling (after completing laser pulse action). Influence of the laser spikes number on plasma was considered. To make computer modelling more affective a method of imaginary source with turn-on time obtained by graphical approach was introduced. To describe accurately the process of implantation of the nanotubes into aluminum matrix depending on the absorption coefficient, thermal and physical properties of the substrate and effect of the plasma pressure accompanying laser irradiation in TCM have to be taken into account. It was found that the implantation of nanotubes into substrate depends not only on their thickness, but also on the randomness of their distribution on the substrate surface and on the thickness of the employed TCM used.
The results are testified experimentally. | 8M 0 |
| 17:30 | Polyoxometalates complex architectures in thin films by exploiting physical and chemical processes at surfaces Authors : Chiara Musumecia, Alessandro Luziob, Mali H. Rosnesc, Chullikkattil P. Pradeepc, Haralampos N. Mirasc, Leroy Croninc, Bruno Pignatarod aSuperlab-Consorzio Catania Ricerche, S.le Primosole 50, 95121, Catania. bDipartimento Ingegneria Chimica dei Processi e dei Materiali, Universitŕ di Palermo, V.le delle Scienze - 90128 Palermo. cDepartment of Chemistry, WestCHEM, University of Glasgow, G12 8QQ Glasgow, L.Cronin@chem.gla.ac.uk dDipartimento di Chimica Fisica “F. Accascina”, Universitŕ di Palermo, V.le delle Scienze - 90128 Palermo, bruno.pignataro@unipa.it Resume : Polyoxometalates (POMs) are active redox systems able to incorporate heteroanions, electrophiles and ligands, and to encapsulate guest molecules within a metal-oxide based cage. They cover an unmatched range of physical and chemical properties that could be exploited for the fabrication of a new class of materials.1
This work was aimed to tune POMs architectures on surfaces by exploiting both spontaneous self-organization, driven by intermolecular and surface forces (through the variation of cluster archetype and/or functionalization), and different physical (wetting/dewetting, pressure-aided) conditions.
Drop cast and Langmuir-Blodgett deposited structures of a range of different POMs have been investigated over silicon based surfaces by means of Scanning Probe Microscopies. A wide landscape of assembling architectures have been obtained such as 0D dots, 1D fibres, 2D lamellas or 3D porous networks, screws and plane-by-plane buildings, demonstrating the high level of versatility of these compounds acting as building blocks for functional materials fabrication.
1. D.-L. Long, R. Tsunashima, L. Cronin, Angew. Chem. Int. Ed., 2010, 49, 1736. | 11M 0 |
| 17:30 | Soft magnetic materials for operation in alternating-current fields Authors : Vlasova Oksana Resume : In the present work, results of an investigation of cladding processes of iron powder with organic components in the form of resins of different grades and an organosilicon polymer are presented. Optimal manufacturing regimes of iron powders with an insulating film, which provides an increase in the electrical resistivity and a substantial decrease (3–4 times) in the eddy-current loss, were determined. A study of the structural state enabled us to establish that, in the cladding of iron powder with an organosilicon polymer, silicon is distributed between powder particles after sintering. Depending on sintering regimes, the value of the magnetic induction varies in the range 0.9—1.3 T at a magnetic field strength of 2500 A/m.
The performed investigation show that in the presence of thin insulating nonmagnetic interlayers in single-pressed powder specimens, eddy-current losses Pe-c decrease abruptly, whereas hysteresis losses Ph increase. In this connection, the reduction of the total magnetic losses at the expense of the decrease in Ph by controlling the composition of the initial material is promising. | 9M 0 |
| 17:30 | Influence of irradiation with Ti ions on C60 fullerites Authors : O.L. Pavlenko, O.P. Dmytrenko, M.P. Kulish, V. Brusentsov, *B.M. Romaniuk, *V.V. Strelchuk Kyiv National Taras Shevchenko University, Faculty of Physics, Volodymyrska 64, Kyiv, Ukraine, 03022. *V.E. Lashkariov Institute of Semiconductor Physics, 41 Nauky ave., Kyiv, Ukraine, 03028. Resume : Significant interest to fullerenes is caused by their properties that can be changed under influence of external conditions. In our work we study radiation stability of the C60 fullerites due to importance of fullerene coverings in the space equipment.
We have irradiated thin film of C60 fullerite (d=1 mkm) with carbide-forming Ti ions (fluencies have been changed from 1.2*1012 up to 0.6*1014 ions/cm2, energy of ions was 140 keV) and studied influence of the irradiation on crystal structure and vibration spectrums of C60. Changes in the crystal structure were observed by X-rays diffraction method ( ) and vibration spectrums were measured with Raman spectroscopy (Ar laser, ).
In the initial state C60 fullerite has fcc phase and is a molecular crystal with 3 diffraction peaks. At fluence of 1.2*1012 ions/cm2 on XRD pattern appearance of new peaks is observed that rise in intensity with increase of the fluence. One more interesting fact is that lattice parameters of the fcc initial phase decrease. Such behavior can be explained by appearance of new additional to Van-der-Waals interaction between the neighboring molecules that causes their approach. Such approaching induces formation of bonds between the molecules, similar to [2+2] cycloaddition. And appearance of new peaks proves about of new phases and can be assign to tetragonal, orthorhombic phase.
This idea is confirmed by Raman spectroscopy. In initial state spectrum was characterized by 10 fully- symmetrical vibration bands: Ag(1-2) and Hg(1-8). At increase of the fluence we observe complicated transformation of the bands. It is well-known that the most sensible to polymerization band is pentagonal pinch mode Ag(2). We observed typical for the polymerization characteristics of Ag(2) mode: lowering of the symmetry, shift in the side of lower frequencies and splitting. Numerical decomposition of the region near Ag(2) mode allows to assign new peaks to formation of dimers, linear chains and tetragonal planes for both samples. But with increase of the fluence up to 0.6*1014 ions/cm2 all the Raman bands disappear and forms one broad band with center near 1575 cm-1 (typical for amorphous graphite) that proves about formation of radiation defects. | 12M 0 |
| 17:30 | Application of glycerol monoacrylate and other new low- toxic monomers in ceramics processing Authors : Agnieszka Szudarska, Mikolaj Szafran Warsaw University of Technology, Faculty of Chemistry 3 Noakowskiego St., 00-664 Warsaw, Poland Resume : Gelcasting is one of the techniques which allow to obtain complex ceramic parts of high quality. It is possible due to controlled reaction of an in situ polymerization in the ceramic slurry, which is composed from ceramic powder, organic monomer, dispersant, activator and initiator. The slurry is poured into a mould of the desired shape, where the entire system polymerizes, and after specified time a rigid, gelled element can be removed. Then it is dried, the organic compounds are burnt out and finally the product is sintered.
The key role in the whole process is played by suitable selection of an organic monomer, which should be able to provide high mechanical strength of the gelled part. Monomers commercially available, e.g. acrylamide, present a lot of disadvantages, such as high toxicity and harmful effect on the environment or they must be used together with an additional cross-linking agent, otherwise green bodies are not tough enough.
For these reason glycerol monoacrylate and other new low-toxic, water soluble, environmentally friendly acrylic monomers based on saccharides have been synthesized recently and their application in gelcasting process of alumina powder has been studied. They do not need the external cross-linking agent owing to the presence of more than two hydroxyl groups in the molecule, which form hydrogen bonds in the polymer network and so good mechanical strength and high density of the products are provided. | 13M 0 |
| 17:30 | Alumina matrix ceramic-metal composites wet processing Authors : Magdalena Gizowska, Mikołaj Szafran, Politechnika Warszawska, Wydział Chemiczny, ul. Noakowskiego 3, 00-664 Warszawa Katarzyna Konopka Politechnika Warszawska, Wydział Inżynierii Materiałowej, ul. Wołoska 141, 02-507 Warszawa Resume : Ceramic-matrix composites due to their unique properties find application in diverse fields. Presence of ductile metal hinder propagation of cracks in ceramic matrix originating from strain exhibiting in the material. This results in, among others, an increase in fracture toughness and thermal shock resistance in comparison with ceramic material.
Slip casting moulding method (counted among wet processing methods) widely used in ceramic industry was applied for ceramic matrix ceramic-metal composite fabrication. This method gives possibility of product shape control without green machining step. Good quality and homogeneity of powder consolidation is crucial in ceramic and ceramic matrix composites fabrication rout as it influences the properties of the material. In case of such complex systems as powders mixture dispersions in liquid medium (slurry) it is indispensable to investigate the phenomena taking place at solid-liquid interface which impose the dispersion stability and govern the interaction characteristics between particles of different kind (ceramic and metallic). Depending on interaction between particles of different kind composite with homogenous and graded concentration of metallic particles can be obtained. In order to obtain graded concentration of metallic particles double layer surrounding particles in the slurry must be of the same charge.
Otherwise, heteroflocculation (e.i. electrostatic attraction of ceramic and metallic particles which are surrounded by ions of different charge) will take place. This results in homogenic distribution of metallic phase. | 14M 0 |
| 17:30 | MOULDING OF BIOGENIC SILICA BY TAPE CASTING METHOD Authors : Katarzyna Konopka , Przemysław Kubiak, Ewa Bobryk, Mikołaj Szafran Politechnika Warszawska, Wydział Chemiczny Resume : Diatomic earth is the sedimentary rock formed by sedimentation of diatoms frustules through thousands of years. Diatoms are unicellular eukaryotic algae, which can be found in almost all aqueous and humid environments. They have unique morphology of skeletons with the pattern such as pores, ridges, areoles and other forms, and their cell walls are made of silica (hydrated silicon dioxide). Because of this specific morphology, diatoms are considered in nanotechnology. On the other hand, the wide application of the diatomaceous earth as building and abrasive materials, fillers and materials used for filtration or insulation results from the fact that this sedimentary rock is available in nature in large quantities and at a low cost. This rock is also easy to posses source of biogenic silica. Because of that diatoms have to be processed and sintered.
The paper presents the results of diatoms consolidation experiments, which analyze the influence of commercially available ceramic binders on the process of molding by tape casting” method with the preservation of the nanopores that naturally exist in diatoms.
The aim of the research was to test the impact of added components, so that the obtained ceramic films could have desirable properties of the materials such as appropriate density of suitable mechanical strength and plasticity, while biogenic silica preserved nanoporous.
The results showed that ceramic binders can help to obtain green ceramic films whit optimal parameters in the non-aqueous system. From prepared ceramic slurries it is possible to obtain ceramic films of appropriate thickness without cracks and other surface defects on large surface. | 10M 0 |
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