bluuebunny/crossref_metadata_2025 huggingface dataset:
Discоvering the Shоrtest Pаth in a Wаrehоuse with аn Innоvаtive Greedy Аlgоrithm's Prоgrаm Based
Authors: Chirici Lapo , Wang Ke Sheng
Published: October 2014

In the erа оf grоwing chаngings, hаving the pоssibility tо gаin а cоmpetitive аdvаntаge in terms оf cutting-edge lоgistics represents оne оf the mаjоr chаllenge nоwаdаys fоr the enterprises. The аim оf the prоject is tо present аn innоvаtive multi-greedy аlgоrithm аpprоаch tо run in аn аutоmаted wаrehоuse prоvided with RFID. The reflection hаs been bаsed оn reаl dаtа gаthered frоm Trаde Ltc, аn Itаliаn bаsed cоmpаny leаder in trаnspоrtаtiоn аnd wаrehоuse mаnаgement. The first needs tо аccоmplish were tо minimize the оrder picking time thrоugh а better stоrаge аssignаtiоn аnd keeping the perfоrmаnce оf the system аt high level, reducing wаsting times between the оperаtоrs. With the presented аpprоаch, by using а greedy аlgоrithms аnd implementing it in wаrehоuse mаnаgement systems, sаtisfаctоry results cаn be аchieved with аn аcceptаble effоrt.
Structural Optimization for Stator Radial Ventilation Cooling System of Turbo Generator
Authors: Wang Jun , Li Gui Qin , Xu Guo Jun , Li Hong Bo , Yuan Xiao
Published: October 2014

For 300 MW inner cooling turbo generator, a discrete model for cooling material flow distribution of radial ventilation cooling system has been developed. The structure optimization is studied with this model. The effect of the radial distance and the tangential distance on stator’s radial flow distribution was analyzed and optimized. The results of the simulation show that with the same inlet-outlet flow pressure the flow deviation increased as the radial distance increased but the tangential distance decreased oppositely.
Development and Deployment of Advanced and Intelligent Manufacturing and Logistics Solutions through the Use of RFID, EDI and Bar Codes
Authors: Evanger Jan Erik , Lie Jørund
Published: October 2014

In this paper we describe the practical application of RFID in production and logistics at the Norwegian board and packaging manufacturer Glomma Papp. Delivery of the system took place during late 2013 and 2014. The company’s goal was to automate its production flow and logistics. There were two options: bar codes or RFID.
Exploring Responsiveness and Flexibility in Multisite Production Environments: The Case of Norwegian Dairy Production
Authors: Nehzati Taravatsadat , Dreyer Heidi C. , Strandhagen Jan Ola , Haartveit Dag E. Gotteberg , Romsdal Anita
Published: October 2014

Industrialized production most often takes place in large-scale systems consisting of multisite units, which are managed with central strategic planning, and decision units and local management teams in order to exploit capacity and scale benefits. Manufacturers are searching for new strategies that will increase their capability to be responsive to market needs while remaining competitive according to cost, time and service level criteria. Responsiveness has mainly been studied in one-dimensional production and supply chain environments, single production sites or the supply chain of a single production site. We argue in this paper that in the fast-moving consumer sector (FMCS) within a multisite production environment, where there is a need for coordination, responsiveness has to be further analyzed. We have explored responsiveness and flexibility in such an environment in order to identify the factors that require and enable responsiveness in a production networks system, and identified a number of factors, which are analyzed in the form of a case study.
Analysis for Different Positions of Nozzle on Air-Assisted Boom Sprayer
Authors: Zuo Wen Long , Liu Xue Mei , Yuan Jin
Published: October 2014

Natural wind, relative position between the nozzle and the outlet of the ram in the air-assistant spray have a great influence on performance. Air-assisted boom sprayer model is developed based on CFD. According to the data of the related parameters of the spray machine, variables of 3-D model were defined. With velocity of natural wind and inlet of the ram , the spraying flow keeping constant, the relative position between the nozzle and the outlet being a research variable, this article calculates the drift rate of the droplets respectively, then analyzes the results scientifically and gets the corresponding conclusion. At the same time, in order to confirm the reliability of the simulation results, this paper makes an experiment, which is done in Shandong agricultural university spray performance laboratory. Studies have shown that drift rate is significantly lower when the nozzles located under outlet position than on the downwind or the upwind .
The Design and Numerical Simulation of Continuous Diffusion Furnace’s Gas-Inlet Tube
Authors: Li Gui Qin , Yu Zhi Ping , Zhang Sheng Cai , Yuan Xiao , Li Hong Bo
Published: October 2014

A variable spacing gas-inlet tube is designed based on the characteristics of continuous diffusion furnace. The mathematics model is constructed to calculate the optimal spacing between two air holes. The gas velocity in the furnace tube is simulated by CFD, and its feasibility is verified.
Sol-Gel Derived Mullite-Gahnite Composite
Authors: Kurajica Stanislav , Tkalčec Emilija , Mandić Vilko , Lozić Iva , Schmauch Jörg
Published: October 2014

Mullite-gahnite composites with different phase-proportions were prepared using sol-gel process. Crystallization path was determined using differential thermal analysis (DTA). X-ray powder diffraction (XRD) was used to study the crystal phases development. The course of the thermal reactions is dominated by the intermediate formation of two spinel phases. The former phase was attributed to gahnite, while the latter to Al-Si spinel. Zn loading decreases amounts of mullite and α-alumina, while increases gahnite and amorphous phase. The observed microstructure of sintered bodies is characterized by fine gahnite particles distributed among larger mullite grains, which is highly favourable for ceramics with high mechanical requirements.
3D Phase-Field Simulation and Characterization of Microstructure Evolution during Liquid Phase Sintering
Authors: Ravash Hamed , Specht Eckard , Vleugels Jef , Moelans Nele
Published: October 2014

Liquid phase sintering (LPS) is widely used as a materials processing technique for hightemperature applications. In LPS, particle-particle contact size and distribution, 3-D coordination number, connectivity, and contiguity are important microstructure parameters which, to a large extent, determine the mechanical properties of the sintered materials. These features all depend on the grain size, solid volume fraction and dihedral angle during sintering. The dihedral angle is an important parameter in LPS. It is the angle formed between the 2 solid-liquid interfaces at the intersection of a grain boundary with the liquid. A higher solid volume fraction, on the other hand, favors a larger 3-D coordination number, connectivity, and contiguity. In practice, studying the correlation between these parameters and direct measurement of them is not a trivial task. Among them, 3-D measurement of dihedral angle is believed to be the most challenging one. In the current study, phase-field modeling is employed to simulate LPS in two phase systems (solid and liquid). Simulations are performed for the different ratios of grain boundary to solid-liquid energies and the different solid volume fractions. To create initial structures with high solid volume fraction, an advanced particle packing algorithm is employed. An extended sparse bounding-box algorithm is used to speed-up the computations and makes it computationally efficient for 3-D simulations. Contiguity, connectivity, and three dimensional coordination number were measured in the self similar regime. The results were compared with empirical rules and experimental data and are used to estimate the mean 3-D dihedral angle.
Influence of Alumina Addition on Low Temperature Degradation of Y2O3-Coated Powder Based Y-TZP Ceramics
Authors: Zhang Fei , Vanmeensel Kim , Inokoshi Masanao , van Meerbeek Bart , Naert Ignace , Vleugels Jef
Published: October 2014

The influence of the addition of 0.25, 2 and 5 wt.% alumina on the mechanical properties and low temperature degradation (LTD) behaviour of 3 mol% yttria-coated ZrO2 powder based Y-TZP ceramics was investigated, and compared to commercial powder based co-precipitated 3Y-TZPs with 0-0.25 wt.% Al2O3 addition. The ceramics were subjected to accelerated hydrothermal degradation in an autoclave in H2O at 134°C up to 40 hrs. X-ray diffraction and Raman spectroscopy were used to assess the LTD behaviour. Incorporating the Y2O3 stabilizer by means of a coating method resulted in a higher LTD resistance without compromising the higher fracture toughness, compared to the co-precipitation method. Alumina addition did not significantly influence the mechanical properties of all Y-TZPs but significantly increased the LTD resistance of the Y-TZP ceramics. The LTD resistance of 0.25 wt% Al2O3 doped TZPs was substantially higher than that of ceramics containing 2 or 5 wt.% Al2O3, which had a comparable susceptibility. The highest LTD resistance for the 0.25 wt.% alumina doped ceramics could be correlated to the solubility limit of alumina in zirconia.
Effect of Particle Size of ZrO2(Y2O3) Powders on the Shrinkage of the Sintered Substrate with Coloring Gradient
Authors: da Silva Paula Cipriano , Magnago Roberto de Oliveira , da Silva Camila Aparecida Araujo , de Almeida Fortes Bianca , dos Santos Claudinei
Published: October 2014

ZrO2(Y2O3)-based ceramics with coloring gradient can facilitate the development of dental prosthesis by the improvement of esthetic properties. In this work, ZrO2 powders with different particle sizes were investigated. White and yellow zirconia powders (TOSOH Corporation-Japan) were characterized by particles size distribution using nanoSight-LM20 analyzer. Furthermore, samples were characterized by X-Ray diffraction, Scanning Electron Microscopy and relative density. Compacts with two layers, one white and one yellow were uniaxially pressed at 80MPa and sintered at 1530°C-120min. The yellow-powder presented average particles size of 180±66nm, while the white-powder presented particles size of 198±73nm. After sintering, full dense ceramics with tetragonal phase were obtained. The linear shrinkage of the yellow and white-layer was 22.75% and 22.05% respectively. This difference in shrinkage is important in the machining of prostheses in ceramic CAD/CAM systems, because they lead to difficulties in adapting this customized prosthesis in patients.
Preparation of Highly-Dispersed Powders of Cobalt, Nickel, Molybdenum and Tungsten Oxides by Modified Sol-Gel Technique
Authors: Trusova Elena A. , Kotsareva Klara V.
Published: October 2014

The modified sol-gel technique for the preparation of Со, Ni, Mo and W oxides nanoand submicron powders as well as binary composites based on them was developed. The optimal parameters of synthesis of metal oxide nanopowders with a particle size less than 100 nm were determined. The developed approach allows to obtain the nanoscale metal oxide particles with the given sizes, varying their within range 10-1000 nm. Mesoporous composites containing Mo-, Co-, Ni-oxides, Al2O3 and Ti-silicate were synthesized, characterized and tested in the catalytic alcohol synthesis from CO and H2. It was found that selectivity to C1-C4-alcohols formed over model catalytic systems reaches 50-85% in temperature range 280-360°С.
Effect of Calcining Temperature of Si3N4 Poly-Hollow Microspheres on the Properties of the Porous Si3N4 Ceramics Prepared by Aqueous Gelcasting
Authors: Wu Jia Min , Zhang Xiao Yan , Li Jia Lu , Yang Jin Long
Published: October 2014

Highly porous Si3N4 ceramics were prepared by aqueous gelcasting using Si3N4 poly-hollow microspheres as pore-forming agent and the effect of calcining temperature of Si3N4 poly-hollow microspheres on their properties was investigated. With the increase of the calcining temperature, the surfaces of the Si3N4 poly-hollow microspheres become coarser and coarser due to more rod-like β-Si3N4 grains appearing on their surfaces. Only the β-Si3N4 phase is observed in the porous Si3N4 ceramics regardless of the calcining temperature. The Si3N4 poly-hollow microspheres distribute uniformly in the Si3N4 green samples and porous Si3N4 ceramics, and they contact with each other, which could restrict the shrinkage, warpage and cracking of the final material. With the increase of the calcining temperature, the porosity of the porous Si3N4 ceramics increases, while shrinkage, flexural strength and fracture toughness decrease.
Synthesis and Luminescence Properties of a Red Nitride Phosphor (CaAlSiN3:Eu2+) for White Light LED Applications
Authors: Chung Shyan Lung , Huang Shu Chi
Published: October 2014

A combustion synthesis method has been developed for synthesis of Eu2+-doped CaAlSiN3 phosphor and its photoluminescence properties were investigated. Ca, Al, Si, and Eu2O3 powders were used as the Ca, Al, Si and Eu sources. NaN3 was added as both solid-state nitrogen source and reducing agent and NH4Cl was added as catalytic agent. These powders were mixed and pressed into a compact which was then wrapped up with an igniting agent (Mg+Fe3O4). The wrapped reactant compact was ignited by electrical heating under a N2 pressure of 0.2-1.0 MPa. Effects of experimental parameters on product yield and photoluminescence properties were investigated. The synthesized CaAlSiN3:Eu2+ phosphor absorbs light in the region of 200-600 nm and shows a broad band emission in the region of 500-800 nm due to the 4f65d1→4f7 transition of Eu2+. The peak emission intensity is ~106 % of a commercially available phosphor, YAG:Ce3+(P46-Y3), and the peak emission wavelength ranges from 610 to 680 nm depending on the Eu2+ concentration upon excitation at 460nm. The synthesized phosphor also shows excellent thermal and chemical stability and thus has a potential application as a red phosphor for white LED lighting.
A Critical Review on Modeling of Fracture Behavior of Ceramic Joints
Authors: Serizawa Hisashi , Murakawa Hidekazu
Published: October 2014

As examples of the most typical methods to determine the shear strength of SiC/SiC composite joints, the asymmetrical four point bending test of a butt-joined composite, the tensile test of a lap-joined composite, and the compression test of a double-notched composite joint were analyzed by using a finite element method with the interface element. From the results, it was found that the shear strength in the asymmetrical bending test was controlled by both the surface energy and the shear strength at the interface regardless of their combination while the strength in the tensile test or the compression test was governed by the surface energy when both the surface energy and the shear strength were large. In addition, the interface element was employed in order to examine the influence of the specimen geometry on the microstructural fracture morphology in nanoSiC/SiC composite during a miniaturized Double Notch Shear (DNS) test. From the serial computations, it is revealed that a relationship between the inter-laminar shear strength and the yield stress seems to be very important for selecting appropriate specimen geometry of the miniaturized DNS test.
On the Role of TiC in the Carbon Steel-Titanium Joining
Authors: Miriyev Aslan , Kalabukhov Sergey , Tuval Eran , Stern Adin , Frage Nachum
Published: October 2014

TiC interfacial layer is formed during titanium alloy to carbon steel diffusion bonding and prevents the formation of FeTi and Fe2Ti intermetallic compounds, which have detrimental effect on the properties of joints. The TiC layer is extremely thermodynamically stable in contact with austenite and is formed at the steel/titanium interface even in the case when carbon content is about 0.1wt.%. The evolution of an initially formed interfacial titanium carbide layer includes its growth and simultaneously changing the composition of austenite (towards lower carbon content) and titanium (towards higher carbon content). The kinetics parameters of the interfacial layer growth (carbon diffusion coefficient and the activation energy) reflect the grain boundary mechanism of carbon diffusion through the interfacial layer with submicron grains microstructure.
Transmission Electron Microscopy of Interfaces in Diffusion-Bonded Silicon Carbide Ceramics
Authors: Tsuda Hiroshi , Mori Shigeo , Halbig Michael C. , Singh Mrityunjay , Asthana Rajiv
Published: October 2014

Diffusion bonding was used to join silicon carbide (SiC) to SiC substrates using three kinds of interlayers: physical-vapor-deposited (PVD) Ti coatings (10 and 20 μm) on the substrate, Ti foils (10 and 20 μm), and a Mo–B foil (25 μm). Two types of substrates were used: chemical-vapor-deposited SiC and SiC fiber bonded ceramic (SA-TyrannohexTM), the latter having a microstructure consisting of SiC fibers and a carbon layer. The microstructures of the phases formed during diffusion bonding were investigated using transmission electron microscopy (TEM) and selected-area diffraction analysis. TEM samples were prepared using a focused ion beam, which allowed samples to be taken from the reacted area. The effect of the interlayer material and the direction of the SiC fibers in the substrate with respect to the interlayer was evaluated. Scanning electron microscopy and TEM revealed good diffusion bonds in all samples; however, some samples exhibited small amounts of microcracking. The diffusion bonded CVD SiC sample using the 10-μm-thick PVD-Ti interlayer formed more of the stable phase and less of the intermediate phases than the sample using the Ti foil. This behavior was caused by the presence of columnar Ti grains in the interlayer, which may have enhanced the migration of Si and C atoms in the interlayer. In the SA-Tyrannohex samples using the Ti-foil interlayer, the chemical reaction proceeded more rapidly when the fibers were parallel to the interlayer than when they were perpendicular. This behavior was likely caused by the hexagonal carbon layer always facing the Ti interlayer in the sample with perpendicular fibers; this peculiar microstructure reduced the mobility of Si and C migrating into the interlayer. The SA-Tyrannohex sample using the Mo–B foil as the interlayer had excellent diffusion bonds with no microcracks or voids. In this system, Mo5Si3C, Mo2C, and Mo5Si3 formed. While phases have anisotropic coefficient of thermal expansion (CTE), the CTE mismatch between those phases and the substrate was apparently smaller than the mismatch in the samples using Ti interlayers.
Compact, Ceramic Heat Exchangers and Microchannel Devices: Joining and Integration
Authors: Lewinsohn Charles , Fellows Joseph , Wilson Merrill
Published: October 2014

Many energy conversion systems use thermal processes to convert chemical energy to mechanical or electrical energy. In these situations, microchannel components can be used to make heat exchangers and microreactors to make processes more energy efficient. Ceramic heat exchangers permit operation at higher temperatures than with other materials. Additionally, compact heat exchangers are highly efficient and cost-effective. This talk will describe principles of design, methods of fabrication, and joining methods for ceramic, compact heat exchangers for integration of such heat exchangers into practical applications. Particular emphasis will be placed on methods for joining silicon carbide to itself and the results of a novel bonding method that can be performed art relatively low temperatures in air. The mechanical behavior, at room temperature and elevated temperature, of this bonding method will be compared to that of diffusion bonded joints.
Brazing of Metals, Alloys and Ceramics Using Rapidly Quenched Ribbon-Type Filler Metal STEMET
Authors: Suchkov A.N. , Fedotov V.T. , Sevryukov O.N. , Kalin В.A. , Ivannikov A.A. , Fedotov I.V. , Morokhov P.V. , Grigoryev A.E.
Published: October 2014

The work shows the main results on the development at NRNU MEPhI of rapidly quenched amorphous and nanocrystalline ribbon-type and powder brazing filler metals based on Al, Cu, Ni, Ti and Zr and their application for brazing of a wide range of materials in nuclear, thermonuclear, aerospace, automotive, aircraft and other industries: from steels, alloys and refractory metals to various ceramics without metallization of their surfaces.
Influencing Factors on the Reactive Wetting of Cu-Sn-Ti- and Ag-Cu-Ti-Alloys on Silicon Carbide – Microstructural Observations, Effects and Multivariate Modelling
Authors: Tillmann Wolfgang , Pfeiffer Jan , Wojarski L.
Published: October 2014

Despite the fact that active brazing is a suitable and well-established method to join ceramics to each other and to metals, issues concerning possible influences on the wetting properties of the used filler alloys are not yet entirely clarified. It is well known that process parameters such as the temperature, the surface roughness of the ceramic, and the atmosphere during wetting influence the wetting angle and the spreading kinetics of the molten filler metal. However, a quantitative description of these influences is still missing.This study closely investigates the isolated effects of the temperature, the surface roughness of the ceramic, as well as the atmosphere on the wetting of Ag-Cu-Ti and Cu-Sn-Ti on silicon carbide. In order to evaluate the effects of the considered factors as well as their interdependencies, a multivariate statistical approach is employed and a linear regression model for both, the contact angle and the spreading area, will be derived. Besides quantitative measurements of the contact angle on solidified sessile drops, microstructural and chemical aspects will be discussed and connected to the results of the wetting experiments as well. By these means, valuable information can be obtained, which lead to a profound understanding concerning changes of the wetting behavior. Furthermore, the study allows a comparison of measurements carried out using varying experimental conditions.
Microwave Energy Application for Materials' Processing and Environmental Technology
Authors: Yoshikawa Noboru
Published: October 2014

Microwave heating was discovered more than 60 years ago. And nowadays, it became popular for the use as domestic ovens. Microwave has also been utilized for the industrial processes, such as drying and roasting. On the other hand, there have been many applications of microwave, being investigated for materials' processing and environmental technologies. They are attempted to take advantage of some specific characteristics in microwave heating, which differs from that of the conventional one. Rapid heating, internal heating, selective heating are the features to be taken into consideration. Moreover, so-called "non-thermal effect" is the additional feature in which researchers are particularly interested. In this article, it is intended to describe fundamental aspects in microwave heating and introduce some selected topics of research projects performed in our research group. They include researches on fabrication of some functional materials and on handling industrial wastes etc. In this article, it is also intended to interpret the phenomena observed in these applications from the fundamental view points of electromagnetic wave interaction with materials.
Graphene Covered Alumina Nanofibers as Toughening Agent in Alumina Ceramics
Authors: Hussainova Irina , Drozdova Maria , Aghayan Marina , Ivanov Roman , Pérez-Coll Domingo
Published: October 2014

Graphene is a promising component for next-generation high-performance structural and multifunctional composite materials. Graphene deposited onto nanofibers of high aspect ratio can serve as reinforcement agent for improving ceramic fracture toughness and electroconductivity. It was found that quality and quantity of graphene sheets on the fiber surface essentially depends on the pyrolysis of carbon source conditions such as gas flow, duration, temperature and the composition of the gas mixture. The alumina/graphene composites of 10 and 15 wt% of nanofibers covered by graphene were produced by spark plasma sintering (SPS) at 1380 °C. Both composites show improvement in mechanical and electrical properties as compared to the monolithic alumina. The main advantage of the graphene growth on the fibers surface is a lack of complicated step of constituents mixing. Graphene platelets are believed to act as toughening agents prevailing crack propagation under loading.
Lithography-Based Ceramic Manufacturing: A Novel Technique for Additive Manufacturing of High-Performance Ceramics
Authors: Schwentenwein Martin , Schneider Peter , Homa Johannes
Published: October 2014

Albeit widely established in plastic and metal industry, additive manufacturing technologies are still a rare sight in the field of ceramic manufacturing. This is mainly due to the requirements for high performance ceramic parts, which no additive manufacturing process was able to meet to date.The Lithography-based Ceramic Manufacturing (LCM)-technology which enables the production of dense and precise ceramic parts by using a photocurable ceramic suspension that is hardened via a photolithographic process. This new technology not only provides very high accuracy, it also reaches high densities for the sintered parts. In the case of alumina a relative density of over 99.4 % and a 4-point-bending strength of almost 430 MPa were realized. Thus, the achievable properties are similar to conventional manufacturing methods, making the LCM-technology an interesting complement for the ceramic industry.
3D Printing of Calcia-Based Ceramic Core Composites
Authors: Zhao Huo Ping , Ye Chun Sheng , Fan Zi Tian
Published: October 2014

Three-dimensional printing has been used as a rapid freeform fabrication process to fabricate a wider range of green ceramic components with complex structures difficult to obtain using traditional ceramic fabrication process. In this study, calcia-based ceramic core composites were fabricated by three dimensional printing and sintering operation. The green bodies were printed using a CaO/TiO2 powder mixture as a precursor material and ethylene glycol as a binder. They were sintered at 1400-1500 °C for 2 h. The phases and microstructures of these samples were characterized by X-ray diffraction and scanning electron microscopy. The effect of TiO2 content and the sintering temperature on the density, hydration resistance and bending strength of the sintered bodies was investigated. It was found that increment of TiO2 content and sintering temperature would result in an increase of density of the sintered bodies and then increase of hydration resistance and bending strength.
Combustion of Gasless System under One-Sided Loading
Authors: Prokofyev Vadim , Smolyakov Victor
Published: October 2014

Controlling the formation of condensed products during combustion of heterogeneous systems is one of the key problems in structural macrokinetics [1]. Modeling of this process at the macroscopic level should describe the change of macrostructural variables: porosity, size and shape of specimens. This paper provides the results of research in macrostructural transformations obtained using the model of a viscous compressible fluid [2].
Two-Step Synthesis of Ultrafine and Nanosized Powders of Tungsten Oxide and Carbide
Authors: Nikolaenko Irina V. , Kedin Nikolay , Shveikin Gennadii
Published: October 2014

In this work a new method of nanoand ultrafine powder of tungsten oxide and carbide synthesis by means of combinating carbon carrier supported classic liquid-phase precipitation and low-temperature microwave treatment was offered. The full range of intermediate substances obtained during thermolysis, reduction and carbidization precursors to final products were presented. The thermolysis of tungstic acid with the formation of tungsten oxide and carbide ultrafine particles of different modifications were studied. It was shown, that cooling ammonium tungstate solution to 4 °C, and use of carbon carrier on the precipitation stage can increase specific surface area from 20 to 100 m2g-1. With the use of SEM precursors particles size were examined (∼200 nm) and the morphology of initial, intermediate and final products was shown.
Carbonaceous Refractory Materials on SHS-Technology
Authors: Mansurov Zulkhair A. , Fomenko Sergey M.
Published: October 2014

This study contains results of carbonaceous SHS-refractory materials application for binding of the graphite products and melting of metals in the induction furnaces. The opportunity of producing strong graphite-graphite bond up to 5 MPa by means of the carbonaceous refractory material that demonstrated high chemical stability in the aggressive liquid metals and alloys environment has been shown. The results of the industrial tests of melting crucibles made of carbonaceous SHS-refractory materials have been presented in the case of aluminium melting. It has been shown that such crucibles stability is 5-6 times higher than that of standard graphite crucibles in aluminium melting conditions. The obtained research results testify that developed carbonaceous material is applied for lining of the induction furnace of melting unit is allow to increase the number of nonferrous metals (bronze) melting cycles from 5 to 6 times in comparison with the traditional graphite crucible melting. High chemical stability of the material to oxidizing environment as well as to metal melts is provided by formation of high-melting compounds in the carbonaceous exothermic systems during SHS-process.
Influence of B4C, SiC and Si3N4 Additions on Microstructures and Selected Properties of Titanium Nitride Matrix Materials Obtained by HPHT Method
Authors: Cyboroń Jolanta , Klimczyk Piotr , Figiel Pawel , Karolus Małgorzata
Published: October 2014

The paper presents the results of the High Pressure and High Temperature (HP-HT) sintering and investigation of Ultra High Temperature Ceramics (UHTC) composites of titanium nitride matrix. The aim of this studies were to determine the influence of additives on the ceramic phase composition, microstructure and selected properties. Three different kind of mixtures were prepared. 8 to 22 wt% B4C, SiC and Si3N4 were added. Composites were sintered under high-pressure high-temperature conditions (HP-HT) using a Bridgman-type apparatus under pressure about 6 GPa. Materials were sintered at the range of 1450 to 1690 ° C, duration of sintering was 60s. The phase composition, microstructure, and the apparent density, Young's modulus, hardness and fracture toughness KIC (HV), using the Vickers indentation method were examined. Sintered titanium nitride with the 22 wt% silicon carbide participation was characterized the best physical and mechanical properties. For this material the relative density is 99%, the Young's modulus 435 GPa, Vickers hardness 18.3 GPa HV1 and fracture toughness 5.5 MPa∙m1/2.
Study of the Thermal Stability and Mechanical Characteristics of MAX Phases of Ti-Al-C(N) System and their Solid Solutions
Authors: Prikhna Tatiana , Cabioc’h Thierry , Gawalek Wolfgang , Ostash Orest , Litzkendorf Doris , Dub Sergey , Loshak Matvey , Sverdun Vladimir , Chartier Patrick , Basyuk Tetyana , Moshchil Victor , Kozyrev Artem , Karpets Myroslav , Kovylaev Valeriy , Starostina Alexandra , Turkrvich Dmitriy
Published: October 2014

The DTA and TG study in air of Ti2Al (C1-xNx) and Ti3AlC2 synthesized under Ar 0.1 MPa pressure and densified in thermobaric conditions at 2 GPa, 1400 °C, for 1 h showed that the increase of the amount of TiC layers in Ti-Al-C MAX phases structures leads to the increase of their stability against oxidation: 321 MAX phase Ti3AlC2 are more stable than Ti2AlC and Ti2Al (C1-xNx) solid solutions both before and after thermobaric treatment. The oxide film formed on the surface of the highly dense (ρ=4.27 g/cm3, porosity 1 %) material based on nanolaminated MAX phase Ti3AlC2 (89 % Ti3AlC2, 6 % TiC, 5 % Al2O3) manufactured by hot pressing (at 30 MPa) made the material highly resistant in air at high temperatures: after 1000 hours of exposition at 600 °C it demonstrated a higher resistance to oxidation than chromium ferrite steels (Crofer GPU and JDA types). Due to the surface oxidation self-healing of defects took place. Besides, the Ti3AlC2 material demonstrated resistance against high-temperature creep and after being kept in H2 at 600 °C for 3h its bending strength reduced by 5 % only. At room temperature the Ti3AlC2 bulk exhibited microhardness Hμ = 4.6 GPa (at 5 N), hardness HV50 = 630 (at 50 N ) and HRA = 70 (at 600 N), Young modulus was 140 ± 29 GPa, bending strength =500 MPa, compression strength 700 MPa, and fracture toughness K1C=10.2 MPa·m0.5.
Poly-Siloxane Impregnation and Pyrolysis of Basalt Fibers for the Cost-Effective Production of CFCCs
Authors: Mingazzini Claudio , Scafè Matteo , Caretti Daniele , Nanni Daniele , Burresi Emiliano , Brentari Alida
Published: October 2014

In this work, the optimisation of basalt fiber CFCCs (Continuous Fiber Ceramic Composites) production is presented, focusing on the development of a silicon-oxycarbide matrix by PIP (Polymer Impregnation Pyrolysis). The use of low cost poly-siloxanes and basalt fibers is particularly promising for transports and constructions, where thermostructural CFCCs would be interesting for vehicle weight reduction and fire-resistant panels, but only on the condition that production costs are kept really low. The basalt/SiCO composites are suitable for mechanical applications up to 600°C and stand up temperatures up to 1200°C, also in oxidative environments. The key parameters to keep the production costs low are the furnace and moulds type, being steel probably the best material for both, since it withstands the pyrolysis temperature and can be easily cleaned, by oxidation, from any residue. Regarding the pyrolysis environment, two conditions were compared, nitrogen flow and vacuum, being perhaps the vacuum procedure less expensive and so potentially more appealing for a large scale production. The microstructure and the thermomechanical characteristics of the obtained composites were compared, Another key parameter in determining the production costs is the number of PIP steps, which has to be minimised. The present results support the conclusion that one PIP step in nitrogen or two PIP steps in vacuum can provide CFCC with satisfactory mechanical characteristics for thermomechanical applications in oxidative environments.
Nonoxide High-Melting Point Compounds as Materials for Extreme Conditions
Authors: Ordanyan S.S. , Vikhman S.V. , Nesmelov D.D. , Danilovich D.P. , Panteleev I.B.
Published: October 2014

Authors have studied the interaction between high-melting compounds from various classes, such as transition-metal carbides, borides, nitrides, and silicides, and covalent-bonded B4C, SiC, Si3N4, AlN etc. (over 160 phase diagrams), ternary B4C-SiC-MedB2, SiC-TiC-TiB2 and other eutectics, which is important for optimizing the sintering temperature, material design and prediction of properties of many materials for high temperature applications including wear, aggressive, impact and radiation conditions. A vast identified group of eutectics with number of components n ≥ 2 has reduced eutectic temperature Тeut. (in some sistems reducing reaches 1200 °C). Noted, that increasing of n suppresses grain growth, which is particularly important for developing nanostructured ceramics via pressureless sintering and for controlling the ceramic's performance. Multiphase ceramics (SiC-TiC-TiB2, B4C-SiC-MedB2, B4C-W2B5-MedB2, B4C-LnB6-MedB2, etc.) feature improved mechanical parameters and high wear and impact resistance.
Reaction Bonded Si3N4 (RBSN)/BN Composites for Industrial Applications
Authors: Cavalli Lorenzo
Published: October 2014

Hexagonal Boron Nitride (h-BN) shows remarkable physical properties, including high thermal stability, low density, low metals wettability, high corrosion resistance and microwave transparency. These features make it extremely interesting for several industrial applications such as furnaces manufacturing and metallurgy industry. Usually, h-BN parts are sintered by expensive high-temperature/high-pressure processes, strongly limiting their size. Here we present a new, cost-effective technique to obtain materials with high h-BN content and large dimensions, suitable for wide-scale industrial applications. Using h-BN and silicon powders as raw materials, reaction-bonded Si3N4/BN composites were obtained by complete nitriding of silicon. Two shaping techniques were exploited: slip casting and uniaxial compression molding using a thermosetting resin (in this case also Silicon Carbide was obtained), leading to materials with different properties. Both large (plates with diameter up to 400mm) and/or complexly-shaped objects (i.e. crucibles) were produced. Such materials were prepared using a Gas Pressure Sintering oven with different process parameters. The as-prepared samples were characterized and tested in a real application, as parts of liquid-silicon infiltration crucibles.
Development of Cordierite Ceramics from Natural Raw Materials
Authors: Rundans Maris , Sedmale Gaida , Sperberga Ingunda , Pundiene Ina
Published: October 2014

Cordierite ceramics are known for their low CTE and high compressive strength values which affords them place in fields where demanding thermal and mechanical properties are required. Development of such ceramics is greatly dependent on materials used. If raw materials are used formation of additional phases and pore/glass formation is expected. The purpose of this research is to examine the process of cordierite development from mixed compositions formed from precursors of the natural raw materials as illite clay, dolomite and quartz sand and synthetic additives – MgO, γ-Al2O3 and their influence on thermal and mechanical properties. It is verified that the addition of 10 wt.% of illite clay and about 20-21 wt.% dolomite in staring compositions at the sintering temperature of 1200 °C results in the development of dense ceramic material with perfect-shaped crystalline cordierite phase and secondary anorthite phase. Sintered cordierite ceramics have been tested, among other properties, for their compressive strength, coefficient of thermal expansion and modulus of elasticity after 20 cycles of thermal shock treatment.
Structural and High Frequency Dielectric Properties of Ba(ZrxTi1-x)O3 Films Prepared by Reactive Magnetron Sputtering Using Metal Targets
Authors: Kim Jin Woong , Shima Hiromi , Yamamoto Takashi , Funakubo Hiroshi , Nishida Ken
Published: October 2014

Ba (ZrxTi1-x)O3 (BZT) films with different Zr contents were deposited on (100)MgO substrates by RF-magnetron reactive sputtering using metal targets. The BZT films epitaxially grew on MgO substrates with only (001)/(100) orientation and had a single perovskite phase. In all cases, the ratio of Ba/Ti was stoichiometry and BZT films possess a dense microstructure. The effect of Zr content on the crystal structure was studied. The grain size was decreased with increasing Zr content. The dielectric properties of the BZT films were also measured at high frequencies region. The reliability of the high-frequency dielectric properties extracted from the measured S11 reflection coefficients. The capacitance for BZT film showed little dispersion and low dielectric loss at 1-18 GHz. These results indicated that we succeeded in depositing high-quality and potential tunable ferroelectrics for high frequency applications.
High Crystalline Cu2O Thin Films Prepared by Electric Current Heating Using Copper Wire
Authors: Okamoto Tomoichiro , Yamazaki Ko , Kuroki Yuichiro , Takata Masasuke
Published: October 2014

Cu wires were heated by electric currents to fabricate Cu2O thin films. The films were successfully deposited on glass substrates placed above the wires at air pressures in the range of 100 - 40 Pa. Then the films were annealed in a controlled atmosphere and investigated the crystallinity, morphology and the time response to illumination of the films. After annealing at 800 °C at atmospheric pressure with oxygen partial pressure of 12 Pa, the crystallinity was increased and the time response of photoconduction was successfully improved.
The Effects of the Annealing Conditions on the Dielectric Properties of the Sol-Gel Derived MgNb2O6 Thin Films
Authors: Ho Yi Da , Chen Kung Rong , Huang Cheng Liang
Published: October 2014

MgNb2O6, a well-known ceramic material with columbite crystal structure, has attracted much attention in microwave integrated circuits and optical applications due to its superior properties, such as its high dielectric constant and an optical band gap. In this work, transparent amorphous-MgNb2O6 thin films were fabricated on ITO/glass substrates using the sol-gel method. The average optical transmission percentage in the visible range (λ=400–800 nm) is over 80% for all MgNb2O6/ITO/glass samples, while the optical band gap is estimated at ~4 eV. On the other hand, the dielectric properties of the MgNb2O6 thin films were very sensitive to the annealing conditions. In this study, the dielectric constant of the films was calculated to be higher than 30 under a 100 kHz AC electric field. The effects of the annealing temperature and atmosphere on the dielectric properties of the MgNb2O6 thin films were investigated.
Correlation between Powder Characteristic and Microstructure Development of Y-Doped BaCeO3
Authors: Araujo H.E. , Souza D.P.F.
Published: October 2014

Ceramics based on Y-doped BaCeO3 were prepared by citrate process. The X-ray fluorescence shows that barium stoichiometry deviation is established during calcination step. Through the SEM analysis of fracture surface of sintered samples it was possible to infer that powder highly deficient of barium shows higher diffusion coefficient during sintering than stoichiometric powder promoting grain growth and, consequently, trapping pores into the grains.
Screen-Printed Ceramic Based MEMS Piezoelectric Cantilever for Harvesting Energy
Authors: Kok Swee Leong , Othman Abdul Rani , Shaaban Azizah
Published: October 2014

Screen-printing technology provides a convenient method in fabricating thick-film conductive circuits and devices in the past few decades. Conventionally, piezoelectric thick-film is printed on alumina substrate with high mechanical Q-factor and resonates at higher frequency outside the range of ambient vibration. As the piezoelectric charge generation is proportional to the mechanical stress on the material, therefore the substrate can be removed in order to lower the natural frequency of the structure. In this paper, a series of piezoelectric ceramic cantilevers were fabricated in the form of free-standing cantilever. An additional layer of ceramic was also introduced to the upper and lower electrode to prevent delamination. The issue of zero resultant stress for the sandwiched piezoelectric cantilever was solved by repeating the electrode-PZT-electrode layer to form a multilayer structure. It was found from the experiment that an electrical output power of 32 μW was generated when it operates at its resonant frequency at 403 Hz.
Influence of Application Technology in the Structural Characteristics of Ceramic Coatings with Advanced Anticorrosive and Tribological Properties
Authors: Vélez David , Muñoz Josemari , Diez José  Antonio
Published: October 2014

Electrophoretic deposition (EPD) of ceramic frits is shown to be a useful coating method for different metal surfaces and geometries since it allows obtaining very smooth surface finishes with precise control of their thickness. By the other hand, these kind of coatings show differences with the coatings obtained by conventional wet application methods as dipping, flow-coating, slushing and spraying.
At this point, CIDETEC has used an own advanced ceramic coating based on no commercial enamels to determinate the best application method to obtain an excellent anticorrosive coating on carbon steel.
In view of possible scaling up to particular industrial applications, a detailed characterization of the microstructure, morphology, physical, chemical and mechanical properties of the coatings was performed. The preliminary studies show that EPD system improves the characteristics of this coating.
Temperature Dependent 4-, 5- and 6-Fold Coordination of Aluminum in MOCVD-Grown Amorphous Alumina Films: From Local Coordination to Material Properties
Authors: Gleizes Alain N. , Samélor D. , Vahlas Constantin , Sarou-Kanian Vincent , Florian Pierre , Massiot Dominique
Published: October 2014

Aluminum 5-fold coordination coexisting with 4-and 6-fold coordination structurally characterizes amorphous aluminum oxide. For nearly 30 years now, 27Al MAS NMR has enabled to detect and later on to quantify this feature thanks to advances in high-resolution instrumentation. The Introduction shortly reviews the results of investigations of 5-coordinate aluminum in amorphous alumina through NMR analysis. Aluminum oxide is not a glass-forming oxide. A convenient way to obtain the amorphous state is by thin film deposition. We present here 27Al NMR analysis of a series of thin films of aluminum oxide prepared by metalorganic chemical vapor deposition (MOCVD) in the temperature range 360 ≤ Td ≤ 720 °C. In this range, low Td yield OH-containing films, while high Td yield nanocrystallites-containing films. The variation of the [4]Al, [5]Al and [6]Al content with Td is presented and discussed. It is correlated with the Td dependence of mechanical and corrosion protection properties. These properties are optimal when the structural disorder is to the utmost. Al coordination dependence on film thickness and the formation of metallic aluminum during the deposition process are also presented.
Sol-Gel Derived Two-Dimensional Nanostructures of Calcium Phosphates
Authors: Prichodko A. , Jonauske V. , Cepenko M. , Beganskiene A. , Kareiva A.
Published: October 2014

Calcium hydroxyapatite (Ca10(PO4)6(OH)2, CHAp), tricalcium phosphate (Ca3(PO4)2, TCP) and calcium oxide (CaO) are the main components of inorganic part of human bones. Such synthetic nanocomposites could be very important implantable materials and using as substitute material for human hard tissues (bones and teeth). In this study, an aqueous sol-gel chemistry route has been developed to prepare nanostructured CHAp thin films on stainless steel substrate. For the preparation of thin films dip-coating and spin-coating techniques were used. The final samples were obtained by calcination of coatings for different time at 1000 °C. For the characterization of surface properties, the X-ray powder diffraction (XRD) analysis, scanning electron microscopy (SEM), atomic force microscopy (AFM) and the contact angle measurements were recorded.
Self-Cleaning and Anti-Fogging Surfaces Based on Nanostructured Metal Oxides
Authors: Lavrenčič Štangar Urška , Tasbihi Minoo , Fresno Fernando , Kete Marko , Gasparotto Alberto , Maccato Chiara , Barreca Davide
Published: October 2014

Self-cleaning and anti-fogging technology is already used in a variety of the products today, among which glazing products prevail. Their function is based on the two principles, either hydrophobic (Lotus effect) or photocatalytic hydrophilic principle. In the latter case, self-cleaning action is based on the combination of photocatalysis and photoinduced superhydrophilicity, where dirt removal by uniform spreading of water over the whole surface is improved with photocatalytic decomposition of organic contaminants. There is a big room to play and a huge potential to improve the properties of existing self-cleaning and anti-fogging surfaces by designing and tailoring new nanoarchitectures of the light-activated thin films. In this lecture we report about the latest achievements and relevance of nanostructured metal oxide surfaces for specific application in photocatalytic self-cleaning. The emphasis is given to the preparation and structure-property relationship of nanocomposite materials based on TiO2 (TiO2-SiO2) and ZnO (ZnO/Co3O4). The emphasis is given also to determination of photocatalytic self-cleaning activity by quantitative and sensitive methods such as fluorescence detection of the first degradation product of terephthalic acid.