bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect Of Heat-Treatment On Microstructure And Magnetic Properties Of Nanocrystallized Mn-Zn Ferrite Powders
Authors: Lee W.H. , Hong C.S. , Chang S.Y.
Published: August 2015

The initial ferrite powders were subjected to high energy ball milling at 300rpm for 3h, and subsequently heat-treated at 573-1273K for 1h. Based on the observation of microstructure and measurement of magnetic properties, the heat-treatment effect was investigated. The size of initial powders was approximately 70μm. After milling, the powders with approximately 230nm in size were obtained, which were composed of the nano-sized particles of approximately 15nm in size. The milled powders became larger to approximately 550nm after heat-treatment at 973K. In addition, the size of particles increased to approximately 120nm with increasing temperature up to 973K. The coercivity of initial powders was almost unchanged after milling, whereas the saturation magnetization increased. As the heat-treatment temperature increased, the saturation magnetization gradually increased and the maximum coercivity was obtained at 773K.
Thermal Analysis On The Kinetics Of Magnesium-Aluminum Layered Double Hydroxides In Different Heating Rates
Authors: Hongbo Y. , Meiling C. , Xu W. , Hong G.
Published: August 2015

The thermal decomposition of magnesium-aluminum layered double hydroxides (LDHs) was investigated by thermogravimetry analysis and differential scanning calorimetry (DSC) methods in argon environment. The influence of heating rates (including 2.5, 5, 10, 15 and 20K/min) on the thermal behavior of LDHs was revealed. By the methods of Kissinger and Flynn-Wall-Ozawa, the thermal kinetic parameters of activation energy and pre-exponential factor for the exothermic processes under non-isothermal conditions were calculated using the analysis of corresponding DSC curves.
A Study On Dispersion Stability Of Nickel Nanoparticles Synthesized By Wire Explosion In Liquid Media
Authors: Kim C.K. , Lee G.-J. , Lee M.K. , Rhee C.K.
Published: August 2015

In this study, nickel nanoparticles were synthesized in ethanol using portable pulsed wire evaporation, which is a one-step physical method. From transmission electron microscopy images, it was found that the Ni nanoparticles exhibited a spherical shape with an average diameter of 7.3 nm. To prevent aggregation of the nickel nanoparticles, a polymer surfactant was added into the ethanol before the synthesis of nickel nanoparticles, and adsorbed on the freshly synthesized nickel nanoparticles during the wire explosion. The dispersion stability of the prepared nickel nanofluids was investigated by zeta-potential analyzer and Turbiscan optical analyzer. As a result, the optimum concentration of polymer surfactant to be added was suggested for the maximized dispersion stability of the nickel nanofluids.
Surface Treatment And Modification Of Graphene Using Organosilane And Its Thermal Stability
Authors: Kim D.-S. , Dhand V. , Rhee K.-Y. , Park S.-J.
Published: August 2015

In this study, graphene was functionalized via acid oxidation in the presence of a mixture of concentrated sulfuric acid and nitric acid. The oxidized graphene was silanized using the coupling agent, 3-aminopropyltriethoxsilane, resulting in functionalized graphene. The oxidized graphene and functionalized graphene were characterized by X-Ray diffraction, Fourier transform infrared spectroscopy, High-resolution micro Raman spectroscopy, thermogravimetric analysis, and atomic force microscopy to confirm the presence of functional moieties on the graphene surface. Thermal studies also demonstrate that the functionalized material is thermally stable up to higher temperatures.
Phase Transformation And Mechanical Properties Of Ti-12.1Mo-1Fe Alloy With Nano-Sized Precipitation
Authors: Lee D.-G. , Seo J. , Li Ch. , Lee Y.
Published: August 2015

Microstructural characterization and aging hardening behaviors of a new designed Ti-12.1Mo-1Fe alloy during solution treatment and aging were investigated in the present study. It is well known that when β-Ti alloys are generally under solution treatment or aging, α phases and ω phases appear or disappear dependent on heat treatment temperature and holding time. It is very necessary to understand the phase transformation phenomenon and to control the microstructure because these phases can control the drastic changes of the mechanical and physical properties of these alloys. According to the calculated [Mo]eq value and the microstructural observation, the β-transus temperature was about 780°. After the solution treatment, this alloy was composed of the β-phase and the microstructure mainly consisted of the equiaxed β grains with the average size of 25 μm. ω phases which were precipitated during aging process, played a more important role to the hardening effect than α phases. The highest hardness value of Ti-12.1Mo-1Fe alloy showed in the condition of the aging temperature of 450°. The hardening due to ω-phase precipitation can lead to a high hardness about 480 Hv but the coarse α-phase result in hardness below 300 Hv.
Extraction Factor Of Pure Ammonium Paratungstate From Tungsten Scraps
Authors: Pee J.-H. , Kim G.H. , Lee H.Y. , Kim Y.J.
Published: August 2015

Typical oxidation process of tungsten scraps was modified by the rotary kiln with oxygen burner to increase the oxidation rate of tungsten scraps. Also to accelerate the solubility of solid oxidized products, the hydrothermal reflux method was adapted. By heating tungsten scraps in rotary kiln with oxygen burner at around 900° for 2hrs, the scraps was oxidized completely. Then oxidized products (WO3 and CoWO4) was fully dissolved in the solution of NaOH by hydrothermal reflux method at 150° for 2hrs. The dissolution rate of oxidized products was increased with increasing the reaction temperature and concentration of NaOH. And then CaWO4 and H2WO4 could be generated from the aqueous sodium tungstate solution. Ammonium paratungstate (APT) also could be produced from tungstic acid using by aqueous ammonium solution. The morphologies (cubic and plate types) of APT was controlled by the stirring process of purified solution of ammonium paratungstate.
Fabrication Of Zn4Sb3 Alloys By A Combination Of Gas-Atomization And Spark Plasma Sintering Processes
Authors: Dharmaiah P. , Kim H.-S. , Lee K.-H. , Hong S.-J.
Published: August 2015

In this study, single phase polycrystalline Zn4Sb3 as well as 11 at.% Zn-rich Zn4Sb3 alloy having ε-Zn4Sb3 (majority phase) and Zn (minority phase) phases bulk samples produced by gas-atomization and subsequently consolidated by spark plasma sintering (SPS) process. The crystal structures were analyzed by X-ray diffraction (XRD) and cross-sectional microstructure were observed by the scanning electron microscopy (SEM). The internal grain microstructure of 11at.% Zn-rich Zn4Sb3 powders shows lamellar structure. Relative density, Vickers hardness and crack lengths were measured to investigate the effect of sintering temperature of Zn4Sb3 samples which are sintered at 653, 673 and 693 K. Relative density of the single phase bulk Zn4Sb3 sample reached to 99.2% of its theoretical density. The micro Vickers hardness of three different sintering temperatures were found around 2.17 – 2.236 GPa.
Porous Magnesium Based Bionanocomposites For Medical Application
Authors: Kowalski K. , Jurczyk M.
Published: August 2015

In this study, Mg-10 wt.% hydroxyapatite nanocomposites and their scaffolds were synthesized using a combination of mechanical alloying and a powder metallurgy methods. The phase and microstructure analysis was carried out using X-ray diffraction, scanning electron microscopy, and the properties were measured using hardness and corrosion testing apparatus. According to the Scherrer method for XRD profiles, the average size of mechanically alloyed Mg+10 wt. % HA for 20 h powders was of order of 21 nm for Mg. The Vickers hardness of the Mg-10 wt.% HA reached 87 HV0.3. The corrosion resistance of the bulk Mg-10 wt.% HA nanocomposite and its scaffolds was investigated in the Ringer’s solution. The potentiodynamic corrosion resistance tests revealed that the porosity of the Mg-10 wt.% HA nanocomposite scaffolds had no negative effects compared to microcrystalline Mg.
The Effect Of Void Formation On The Reliability Of ED-XRF Measurements In Lead-Free Reflow Soldering
Authors: Koncz-Horváth D. , Gergely G. , Gácsi Z.
Published: August 2015

In lead-free reflow soldering, the presence of voids should be taken into account. For this reason, the effect of the applied heating profiles was examined via the characterization of voids in galvanic and immersion Sn coatings. According to EU Directive 2002/95/EC, the screening of Pb element of reflow soldering (i.e. of electrical and electronic equipment) is necessary; and the practical implementation of this measurement is largely affected by the characteristics of the solder (i.e. the presence of voids and the inhomogeneity of the solder). Comparing the results of the above two coating methods, it was found that by chemical coating more voids were formed and the detected lead content was higher than for galvanic Sn. The standard deviation of Ag and Cu concentrations was mainly influenced by the appearance of large compounds in the second case, while with chemical coating, no large compounds were formed due to the elevated number of voids.
Effects Of Nickel On The Microstructure And The Mechanical Properties Of Sn-0.7Cu Lead-Free Solders
Authors: Gyenes A. , Simon A. , Lanszki P. , Gácsi Z.
Published: August 2015

This paper investigates the effects of small amount nickel addition (0, 200, 400, 800, 1800 ppm) on the microstructure and the mechanical properties of Sn-0.7Cu lead-free solder alloys. It is known that even ppm level Ni additions have significant effects on the microstructure of Sn-Cu solder alloys. Ni suppresses the growth ofβ-Sn dendrites in favour of eutectic formation. As the nickel content increases, the microstructure undergoes a morphological evolution from hypoeutectic through fully eutectic to hypereutectic. Along with these transformations, the mechanical properties of the alloy also significantly change. Based on the experimental results presented in this paper, the Sn-0.7Cu solder achieves maximum strength at the addition level of 800 ppm Ni, when the microstructure becomes fully eutectic.
Morphology Change Of Si Deposit In Molten Salt Electrorefining
Authors: Ryu H.Y. , Kwon S.C. , Han M.H. , An Y.S. , Lee J.S. , Lee J.H.
Published: August 2015

The effects of processing parameters on the morphology change in a Si deposit recovered by means of molten salt electrorefining are evaluated using electrochemical techniques such as cyclic voltammetry and chronopotentiometry at 800°C. It was found that concentration of K2SiF6 and current density were important parameters in determining deposit size. Higher concentrations of K2SiF6 were effective in coarsening the silicon deposit and decreasing the cell potential. Silicon nanofiber was recovered at 5 wt% of K2SiF6 whereas dense particles were prepared at 30 and 50 wt% of K2SiF6. The morphology of the Si deposit was determined by the concentration of Si in the electrolyte which is related to the formation of crystal and growth of Si. The formation mechanism of the Si deposit was interpreted by using high resolution TEM as well as electrochemical properties.
Investigation Of Intermetallic Compounds In Sn-Cu-Ni Lead-Free Solders
Authors: Nagy E. , Kristaly F. , Gyenes A. , Gacsi Z.
Published: August 2015

Interfacial intermetallic compounds (IMC) play an important role in Sn-Cu lead-free soldering. The size and morphology of the intermetallic compounds formed between the lead-free solder and the Cu substrate have a significant effect on the mechanical strength of the solder joint.

In the soldering process of Sn-Cu alloys, Cu6Sn5 intermetallic compounds are formed. The complex structural behaviour of Cu6Sn5 IMC is temperature- and composition-dependent and it is long since subject to scientific research. The Cu6Sn5 phase basically exists in two crystal structures: hexagonal η-Cu6Sn5 (at temperatures above 186°C) and monoclinic η’-Cu6Sn5 (at lower temperatures). In the presence of Ni in the solder, the η-η’ transformation does not occur, therefore, the η-Cu6Sn5 phase remains stable.

In this study the role of Ni in the (Cu,Ni)6Sn5 intermetallic compound in Sn-Cu lead-free solders was examined. Sn-Cu alloys with different Cu content (0.5 to 1 mass%) were modified through Ni addition. The morphology of the intermetallic compounds of the modified Sn-Cu alloys was investigated by optical microscopy (OM) and scanning electron microscopy (SEM), the IMC phases were examined with X-ray diffraction method (XRD).
Extraction Of Cobalt From Spent CMB Catalyst Using Supercritical CO2
Authors: Joo S.-H. , Shin S.M.
Published: August 2015

The metal extraction from spent CMB catalyst using supercritical CO2(scCO2) was investigated with single organic system, binary organic system and ternary organic system to extract metal ions. Leaching solution of spent CMB catalyst containing 389 mg L−1 Co2+, 187 mg L−1 Mn2+, 133 mg L−1 Na+, 14.97 mg L−1 Ca2+ and 13.2 mg L−1 Mg2+. The method consists of scCO2/ligands complexation process and metal extraction process at 60°C and 200bar. The result showed the Co and Mn was selectively extracted from Mg, Ca and Na in the ternary system of mixture of Cyanex272, DEA and Alamine304-I.
Correlation Between Superheated Liquid Fragility And Onset Temperature Of Crystallization For Al-Based Amorphous Alloys
Authors: Guo J. , Hu X. , Liu J. , Feng T. , Yoon E.Y. , Kim H.S.
Published: August 2015

Amorphous alloys or metallic glasses have attracted significant interest in the materials science and engineering communities due to their unique physical, mechanical, and chemical properties. The viscous flow of amorphous alloys exhibiting high strain rate sensitivity and homogeneous deformation is considered to be an important characteristic in thermoplastic forming processes performed within the supercooled liquid region because it allows superplastic-like deformation behavior. Here, the correlation between the superheated liquid fragility, and the onset temperature of crystallization for Al-based alloys, is investigated. The activation energy for viscous flow of the liquid is also investigated. There is a negative correlation between the parameter of superheated liquid fragility and the onset temperature of crystallization in the same Al-based alloy system. The activation energy decreases as the onset temperature of crystallization increases. This indicates that the stability of a superheated liquid can affect the thermal stability of the amorphous alloy. It also means that a liquid with a large superheated liquid fragility, when rapidly solidified, forms an amorphous alloy with a low thermal stability.
Chemical Homogenization Of Liquid Steel Flowed Through Continuous Casting Slab Tundish During Alloying Process
Authors: Cwudziński A.
Published: August 2015

This paper presents the results of research on the behaviour of an alloy addition in steel flowing through the tundish used for casting slabs. The device under examination is a wedge-shaped single-nozzle tundish of a capacity of 30 Mg. Due to the complexity of alloy addition dissolution and dispersion in metallurgical processes, a decision was made to use the Species Model available within the Ansys-Fluent®program. For describing the turbulence, the Realizable k-ɛmodel was chosen. By defining the heat losses on respective planes making up the virtual model, the non-isothermal conditions existing during the flow of liquid steel through the tundish were considered. From the performed numerical simulations, the fields of steel flow and steel temperature and alloy addition concentration in the tundish working space were obtained. In order to accurately illustrate the process of chemical homogenization in the tundish working space, mixing curves were recorded. Based on the obtained results (mixing curves), the mixing time needed for achieving the 95% level of chemical homogenization was calculated.
New Wear Resistant Iron-Base Matrix Materials For The Fabrication Of Sintered Diamond Tools
Authors: Konstanty J. , Romański A. , Baczek E. , Tyrala D.
Published: August 2015

The possibility of the use of inexpensive iron-base powders in the production of sintered diamond tools is again explored. Ball-milled Fe-Ni-Cu-Sn-C and Fe-Mn-Cu-Sn-C powders were consolidated to a virtually pore-free condition by hot pressing at 900°C. The resultant materials are characterised by a combination of high Knoop hardness, 260-440 and yield strength, 780-1350 MPa, and resistance to abrasion. These properties can be significantly modified by changing the milling time.
Dimensional Changes, Microstructure, Microhardness Distributions And Corrosion Properties Of Iron And Iron-Manganese Sintered Materials
Authors: Kupková M. , Hrubovčáková M. , Zeleňák A. , Sułowski M. , Ciaś A. , Oriňáková R. , Turoňová A. Morovská , Žáková K. , Kupka M.
Published: August 2015

Iron samples and Fe-Mn alloys with Mn content of 25 wt.% and 30 wt.% were prepared by blending, compressing and sintering with the aim to study their dimensional changes, microstructure, microhardness distribution and primarily the electrochemical corrosion behaviour in a simulated body environment.

The light microscopy (LM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and micro-hardness measurements revealed a microheterogeneous multiphase structure of sintered Fe-Mn samples. The potentiodynamic tests have demonstrated that the corrosion rates of such Fe-Mn alloys immersed in Hank’s solution were higher than those for a pure iron, and also higher than the rates reported for homogeneous Fe-Mn alloys.
Analysis Of Die Design For The Stamping Of A Bathtub
Authors: Hojny M. , Woźniak D. , Głowacki M. , Żaba K. , Nowosielski M. , Kwiatkowski M.
Published: August 2015

The paper presents example results of numerical and photogrammetric analysis leading to identify the causes of cracking and wrinkling during bathtub W1200 production. The verification of tools for the stamping of bathtub W1200 was performed using finite element method and photogrammetric system ATOS Triple Scan. A series of industrial tests was conducted to identify the model parameters. The major and minor strain distributions obtained from the finite element simulations were used in conjunction with the forming limit diagram to predict the onset of fracture. In addition, the effects of blank holder pressure and friction on the occurrence of fracture and wrinkling were investigated.
Quality Requirements Put On The Inconel 625 Austenite Layer Used On The Sheet Pile Walls Of The Boiler’s Evaporator To Utilize Waste Thermally
Authors: Słania J. , Krawczyk R. , Wójcik S.
Published: August 2015

Quality requirements and tests taken on the surfacing layer Inconel 625 are presented in the article. The reasons of using surfacing layer Inconel 625 and technologies of its making with a particular emphasis on the CMT method are described. Quality requirements for the surfacing weld Inconel 625 are provided. Basic requirements included in the Merkblatt 1166, as well as additional requirements, which are reflected in the technical specifications of the boilers’ producers are specified.
The Kinetics Of Ti-1Al-1Mn Alloy Thermal Oxidation And Charcteristic Of Oxide Layer
Authors: Klimecka-Tatar D. , Borkowski S. , Sygut P.
Published: August 2015

The main goal of the study was to carry out the treatment of cyclic oxidation of Ti alloy (Ti-1Al-1Mn) in air atmosphere. Based on measurements of mass gain of titanium alloy samples (Ti-1Al-1Mn) the kinetic oxidation curves during cyclic annealing were determined. The oxidized surface of the titanium alloy was carefully observed with optical microscopy equipment and the geometrical development, shape and surface morphology were defined. The phase composition of the obtained oxide layers on the Ti-alloy with qualitative analysis of the X-ray were defined. Since titanium alloys are among the most widely used metallic materials in dental prosthetics the corrosion measurements in a solution simulating the environment of the oral cavity were carried out. The results confirmed that the used titanium alloy easily covered with oxides layers, which to some extent inhibit the processes of electrochemical corrosion in artificial saliva solution.
The Influence Of The Rare Earth Metals Modification On The Fracture Toughness Of G17CrMo5-5 Cast Steel At Low Temperatures
Authors: Dzioba I. , Kasińska J. , Pała R.
Published: August 2015

This paper presents the influence of the rare earth metals (REM) modification on mechanical properties and fracture toughness of G17CrMo5-5 cast steel at low temperatures. The REM was in the form of mishmetal. The research has been performed on serial (several) industrial melts. The fracture toughness values of unmodified and modified cast steel at the temperature range from −80°C to 20°C were tested. The reference temperatures of the brittle-to-ductile transition, TQ, for both unmodified and modified cast steel were determined. The positive influence of the modification by REM on the fracture toughness and the reference temperature TQ are shown.
Effect Of Milling Time On Microstructure Of AA6061 Composites Fabricated Via Mechanical Alloying
Authors: Tomiczek B. , Pawlyta M. , Adamiak M. , Dobrzański L.A.
Published: August 2015

The aim of this work is to determine the effect of manufacturing conditions, especially milling time, on the microstructure and crystallite size of a newly developed nanostructural composite material with the aluminium alloy matrix reinforced with halloysite nanotubes. Halloysite, being a clayey mineral of volcanic origin, is characterized by high porosity and large specific surface area. Thus it can be used as an alternative reinforcement in metal matrix composite materials. In order to obtain this goal, composite powders with fine microstructures were fabricated using high-energy mechanical alloying, cold compacting and hot extrusion techniques. The obtained composite powders of aluminium alloy reinforced with 5, 10 and 15 wt% of halloysite nanotubes were characterized with SEM, TEM and XRD analysis. It has been proven that the use of mechanical alloying leads to a high degree of deformation, which, coupled with a decreased grain size below 100 nm and the dispersion of the refined reinforcing particles–reinforces the material very well.
Theoretical And Experimental Analysis Of Aluminium Bars Rolling Process In Three-High Skew Rolling Mill
Authors: Stefanik A. , Morel A. , Mróz S. , Szota P.
Published: August 2015

Technology of round bars rolling on a three-high skew rolling mills allows rolling of standard materials such as steel and aluminum, as well as new materials, especially hard deformable materials. The paper presents the results of theoretical and experimental rolling process of aluminum bars with a diameter of 20 mm. As the stock round bars with a diameter of 25 mm made of aluminum grade 1050A and aluminum alloy grade 2017A were used. The rolling process of aluminum bars has been carried out in a single pass. The numerical analysis was carried out by using computer program Forge2011®. On the basis of theoretical research it has been determined the state of deformation, stress and temperature distribution during rolling of aluminum bars. In addition, the results of theoretical research allowed to determine the schema of the metal plastic flow in the roll gap. Verification of the theoretical research was carried out during the rolling of aluminum bars on the RSP 40/14 laboratory three-high skew rolling mill. From the finished bars were taken the samples to set the shape and compared with the results of theoretical research. Finished aluminum round bars were characterized by low ovality and good surface quality.
Numerical Modelling Of Thermal And Structural Phenomena In Yb:YAG Laser Butt-Welded Steel Elements
Authors: Kubiak M. , Piekarska W. , Stano S. , Saternus Z.
Published: August 2015

The numerical model of thermal and structural phenomena is developed for the analysis of Yb:YAG laser welding process with the motion of the liquid material in the welding pool taken into account. Temperature field and melted material velocity field in the fusion zone are obtained from the numerical solution of continuum mechanics equations using Chorin projection method and finite volume method. Phase transformations in solid state are analyzed during heating and cooling using classical models of the kinetics of phase transformations as well as CTA and CCT diagrams for welded steel. The interpolated heat source model is developed in order to reliably reflect the real distribution of Yb:YAG laser power obtained by experimental research on the laser beam profile.

On the basis of developed numerical models the geometry of the weld and heat affected zone are predicted as well as the structural composition of the joint.
The Assessment Of The Structure And Properties Of High-Carbon Steel Wires After The Process Of Patenting With Induction Heating
Authors: Wiewiórowska S. , Muskalski Z.
Published: August 2015

One of the most important types of heat treatment that high-carbon steel wires are subjected to is the patenting treatment. This process is conducted with the aim of obtaining a fine-grained uniform pearlitic structure which will be susceptible to plastic deformation in drawing processes. Patenting involves two-stage heat treatment that includes heating the wire up to the temperature above Ac3 in a continuous heating furnace (in the temperature range of 850÷1050°C) followed by a rapid cooling in a tank with a lead bath down to the temperature range of 450÷550°C. The patenting process is most significantly influenced by the chemistry of the steel being treated, as well as by the temperature and the rate of heating and cooling of the wire rod or wire being patented.

So far, heating up to the austenitizing temperature has been conducted in several-zone continuous gas-fired or electric furnaces. Recently, attempts have been made in a drawing mill to replace this type of furnace with fast induction heating, which should bring about an energy saving, as well as a reduced quantity of scale on the patented wire.

This paper presents the analysis of the structure and mechanical properties of wires of high-carbon steel with a carbon content of 0.76%C after the patenting process using induction heating for different levels of the coil induction power.
Characterization Of An Equal Channel Angular Pressed Al-Zn-In Alloy
Authors: Banjongprasert C. , Jak-Ra A. , Domrong C. , Patakham U. , Pongsaksawad W. , Chairuangsri T.
Published: August 2015

Equal channel angular pressing (ECAP) is a technique that creates a high accumulated strain in metals and results in ultrafine-grained structure. In this study, Al-5Zn-0.02In was processed by ECAP at a room temperature using route Bc through an ECAP die (press angle of Φ = 100° and Ψ = 20°). The samples were subjected to ECAP with 1, 2, 3 and 4 passes. The processed specimens were characterized using electron backscatter diffraction (EBSD). The results confirmed the grain refinement of the alloy after ECAP to an average grain size less than 5 μm after 4-pass ECAP. The microhardness test shows that the hardness increased with the number of passes. The hardness of the cross-sectional area of the sample was similar to that tested along the pressing direction.
Electrolytes For Intermediate Temperature Solid Oxide Fuel Cells
Authors: Rękas M.
Published: August 2015

Solid electrolytes for construction of the intermediate-temperature solid oxide fuel cells, IT-SOFC, have been reviewed. Yttrium stabilized tetragonal zirconia polycrystals, YTZP, as a potential electrolyte of IT-SOFC have been highlighted. The experimental results involving structural, microstructural, electrical properties based on our own studies were presented. In order to study aluminum diffusion in YTZP, aluminum oxide was deposited on the surface of 3 mol.% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP). The samples were annealed at temperatures from 1523 to 1773 K. Diffusion profiles of Al in the form of mean concentration vs. depth in B-type kinetic region were investigated by secondary ion mass spectroscopy (SIMS). Both the lattice (DB) and grain boundary (DGB) diffusion were determined.
Solute-Vacancy Clustering In Al-Mg-Si Alloys Studied By Muon Spin Relaxation Technique
Authors: Nishimura K. , Matsuda K. , Komaki R. , Nunomra N. , Wenner S. , Holmestad R. , Matsuzaki T. , Watanabe I. , Pratt F.L.
Published: August 2015

Zero-field muon spin relaxation experiments were carried out with Al-1.6%Mg2Si, Al-0.5%Mg, and Al-0.5%Si alloys. Observed relaxation spectra were compared with the calculated relaxation functions based on the Monte Carlo simulation to extract the dipolar width (Δ), trapping (νt), and detrapping rates (νd), with the initially trapped muon fraction (P0). The fitting analysis has elucidated that the muon trapping rates depended on the heat treatment and solute concentrations. The dissolved Mg in Al dominated the νt at lower temperatures below 120 K, therefore the similar temperature variations of νt were observed with the samples mixed with Mg. The νt around 200 K remarkably reflected the heat treatment effect on the samples, and the largest νt value was found with the sample annealed at 100°C among Al-1.6%Mg2Si alloys. The as-quenched Al-0.5%Si sample showed significant νt values between 80 and 280 K relating with Si-vacancy clusters, but such clusters disappeared with the natural aged Al-0.5%Si sample.
Hydrogen Sensor Of TiO2-Based Nanomaterials
Authors: Łysoń-Sypień B. , Zakrzewska K. , Gajewska M. , Radecka M.
Published: August 2015

The aim of this research was to examine gas sensing properties of TiO2 based nanomaterials. Nanopowders of Cr doped TiO2 with constant Specific Surface Area, SSA, were obtained using Flame Spray Synthesis technique, FSS. Nanomaterials were characterized by Brunauer – Emmett – Teller adsorption isotherms, BET, X – ray diffraction, XRD, Transmission Electron Microscopy, TEM, optical spectrometry UV – vis with the use of an integrating sphere as well as impedance spectroscopy. Detection of hydrogen was carried out over the concentration range of 50 - 3000 ppm at the temperatures extending from 200 to 400°C and synthetic air working as a reference atmosphere. As a result of experiments it appeared that incorporation of 5 at.% of Cr into TiO2 improved hydrogen sensing features due to small crystallite size and predominance of rutile polymorphic phase.
Reduction Kinetics Of NiS Sulphide
Authors: Smoła G. , Poczekajło A. , Grzesik Z.
Published: August 2015

Reduction mechanism and kinetics of NiS nickel sulphide obtained during the process of nickel sulphidation, have been studied as a function of temperature (723-873 K). It has been found that the reduction process follows linear kinetics with activation energy of 103 kJ/mol. It is important to note that during nickel sulphidation and after the reduction of nickel sulphide, the product sample shows highly developed surface, creating thus the potential possibilities to be applied in heterogeneous catalysis.
Effect Of The Gadolinium Oxide Addition On The Electrical Properties Of Tetragonal Zirconium Dioxide
Authors: Cyran J. , Wyrwa J. , Drożdż E. , Dziubaniuk M. , Rękas M.
Published: August 2015

The aim of this work was examination of gadolinium-doped 3YSZ electrical and structural properties. Such materials may be used as electrolytes in intermediate temperature solid oxide fuel cells (IT-SOFC). First step of the research was synthesis of 3YSZ with different contents of gadolinium (0.25; 0.5; 1.0 at %). Prepared materials were characterized by high porosity. No effect of gadolinium addition on grain size was observed. The experimentally determined values of grain interiors electrical conductivities for gadolinium doped samples are comparable to grain interior conductivities of gadolinium free tetragonal zirconia. On the other hand, a clear effect of gadolinium addition on electrical conductivity of grain boundaries was observed. It was found that 3YSZ containing 0.25 at. % Gd was the most promising from the investigated materials as a solid electrolyte for IT SOFC.
Some Aspects Of Infiltration Of High Speed Steel Based Composites With Iron Addition
Authors: Madej M.
Published: August 2015

Attempts have been made to describe the influence of the production process parameters and additions of iron powders on properties of copper infiltrated HSS based composites. The powder compositions used to produce skeletons for further infiltration were: M3/2, M3/2+20% Fe and M3/2+50% Fe. The powders were cold pressed at 800 MPa. The infiltration process was carried out in vacuum. Both green compacts and preforms sintered for 60 minutes at 1150°C in vacuum were contact infiltrated with copper to yield final densities exceeding 97% of the theoretical value.

The as-infiltrated composites were tested for Brinell hardness and bending strength, and subjected to wear tests performed by block-on-ring wear tester. From the analysis of the obtained results it has been found that the mechanical properties are mainly affected by the manufacturing route and composition of porous skeletons used for infiltration. Considerable differences in hardness between materials obtained from the two infiltration routes have been observed, with lower wear rates achieved after direct infiltration of green compacts.
The Influence Of Repair Welded Joint On The Life Of Steam Pipeline Made Of Cr-Mo Steel Serviced Beyond The Calculated Working Time
Authors: Zieliński A. , Golański G.
Published: August 2015

The aim of the paper was to examine the influence of repair welded joints on the service life of steam pipelines for over 220 000 hours of service in creep conditions. The research included the study of the microstructure using scanning microscopy, the tests on mechanical properties at room and elevated temperature, determining the nil ductility transition temperature, and short-time creep tests to determine the residual life of the material. The tests allowed determining the time of further safe operation of elements of the steam pipeline with a repair welded joint, with reference to the base material, and the welded joint after service. The assessment of residual life and disposable residual life, and at the same time determining the possible time of further safe operation, has an essential meaning in the case of elements serviced considerably beyond the calculated working time.
Critical Assessment Of The Issues In The Application Of Hilbert Transform To Compute The Logarithmic Decrement
Authors: Majewski M. , Magalas L.B.
Published: August 2015

The parametric OMI (Optimization in Multiple Intervals), the Yoshida-Magalas (YM) and a novel Hilbert-twin (H-twin) methods are advocated for computing the logarithmic decrement in the field of internal friction and mechanical spectroscopy of solids. It is shown that dispersion in experimental points results mainly from the selection of the computing methods, the number of oscillations, and noise. It is demonstrated that conventional Hilbert transform method suffers from high dispersion in internal friction values. It is unequivocally demonstrated that the Hilbert-twin method, which yields a ‘true envelope’ for exponentially damped harmonic oscillations is superior to conventional Hilbert transform method. The ‘true envelope’ of free decaying strain signals calculated from the Hilbert-twin method yields excellent estimation of the logarithmic decrement in metals, alloys, and solids.
Immunoexpression of Ki67 and p53 in the Dental Follicles of Impacted Teeth
Authors: Emoke Fulop , Adina Coşarcă , Mariana Păcurar , Alina Ormenişan , Adriana Monea , Grigoraş R , Simona Mocan
Published: August 2015

Aim. The purpose of this study was to evaluate the morphological aspects of dental follicles associated with impacted teeth and the immunoexpression of Ki 67 and p53, in the remaining epithelium from impacted third molars and canines. Another aspect was to identify the transformation of the remaining epithelium within the odontogenic lesions.

Material and method. We included in the study a number of 100 dental follicles, of which only 62 met the inclusion criteria. The immunohistochemical reactions were carried out in the Immunohistochemistry Lab at the Department of Histology of the University of Medicine and Pharmacy of Târgu Mureş. We counted 100 cells from the remaining epithelial islands from which we determined the percentage of labeled cells for both markers. After this all data were subjected to a statistical analysis.

Results. Out of the 62 specimens 44 were from females and 28 from males. Positive results were obtained for the two markers but not for all cases. We have also found a positive correlation regarding the immunolabeling of the two markers (p=0.002 in canines, p=0.0001 in molars). Median values for ki67 were statistically significantly higher than the values for p53 for both types of dental follicles.

Conclusions. Both markers were expressed in the remaining epithelial islands. The stronger expression of Ki67 in the follicles of impacted molars can demonstrate the higher frequency of odontogenic cysts in this area.
Bisphosphonate-Related Osteonecrosis of the Jaws: a real Challenge for Dentists
Authors: Ioana-Auriţa Albu , Cecilia Petrovan , Mariana Păcurar , Albu DE , Csinszka K.-Ivacson A , Golu VM , Copotoiu C
Published: August 2015

Background: Osteonecrosis of the jaw is a serious complication associated with oral and intravenous bisphosphonate therapy. Its pathogenesis is not well understood and its management is difficult. The aim of ourstudy was to evaluate the awareness of dentists in Târgu Mureş on the possibilities of treating patients who are treated with bisphosphonate in dental offices.

Material and method: We carried out a questionnaire-based study among dentists in Târgu Mureş reaching important issues such as: if the patient is asked if medical history follows / followed treatment with bisphosphonates, if they made surgical treatment in these patients, if they know under what conditions can they perform this treatment, if they deem it is necessary to contact the prescriber before surgical treatment.

Results: Seventy questionnaires were returned. During the medical history most clinicians (60%) asked the patients whether they follow/followed treatment with bisphosphonates and most of them (42.85%) did not perform treatments in these patients. While 85.71% of respondents declared that they do contact the prescriber before performing surgical treatment, 48,57% were not aware under what conditions they could undergone the treatment.

Conclusions: The dentists did not seem to be well informed about this pathological entity, known only since 2003. In the absence of appropriate protocols they could not provide a high quality treatment and in these circumstances they might do more harm than good.
The frequency of dental caries in adult patients with gastroesophageal reflux disease
Authors: Sîmpălean DS , Dana Ghiga , Petrişor M , Măruşteri M , Bacârea V , Simona Băţagă
Published: August 2015

Introduction. The aim of the study was to evaluate the frequency of dental caries in adults patients with gastroesophageal reflux disease.

Material and method. A cross-sectional study was performed between November 2013 and October 2014. All subjects who agreed to participate to the study were asked to complete a questionnaire regarding personal information, oral hygiene and dental evaluation. The individuals with complete false teeth (superior and inferior removable prosthetic devices) were excluded from the study. The study included 134 people divided in two groups, based on upper gastrointestinal endoscopy: a group with gastroesophageal reflux disease (71), and a control group (63). Dental evaluation was performed by a dentist blind to the diagnosis of the subjects. Dental caries were evaluated by applying the decayed, missing, and filled teeth index (DMFT index). The statistical significance was defined as p<0.05.

Results. From 71 subjects included in GERD group, 33 (46.48%) were males and 38 females (53.52%) with a mean age of 44.99±11.19 (42, 59.15% from urban area and 29, 40.85%, from rural area). In the control group we included 28 (44.44%) males and 35 (55.56%) females (mean age 43.84±9.48) and 29 (46.03%) subjects were from urban area and 34 (53.97%) from rural area. DMFT index in GERD group was 19.49±4.28 and in control group 18.16±4.54 (p<0.05).

Conclusions. The present study showed that there is no difference between GERD and control group, regarding the frequency of dental caries.
Piggy-back Hepatic Transplant Technique and Veno-venous Bypass Without Cardiac Arrest: A Multidisciplinary Approach in Borderline T3b/T3c Renal Tumors
Authors: Nechifor-Boila IA , Suciu H , Andrada Loghin , Angela Borda , Maier A , Orsolya Martha , Chibelean C
Published: August 2015

Surgery for renal cell carcinomas with tumor thrombus extending in the Inferior Vena Cava (IVC) can be particularly challenging, especially in the retrohepatic and intraatrial situations (T3b and T3c). Classically, these tumors require the intraoperative use of cardio-pulmonary by-pass (CPB) and deep hypothermic circulatory arrest (DHCA), that can result in specific complications (stroke, platelet dysfunction), with increased postoperative morbidity rates.

In urological practice, a particular IVC preparation method is currently in use, allowing full control both upon the IVC and its tributaries. It is derived from the “piggy-back” liver transplantation technique and implies the resection of all hepatic ligaments, leaving the hepatic vascular connections intact. This procedure is joined by a form of veno-venous bypass (between the right atrium and the infrarenal IVC) that allows a constant central venous pressure (by assuring blood return), with less bleeding and without the need for CPB and DHCA (avoiding, in this way, their inherent complications). All in all, these recently-introduced procedures can offer better thrombus control, improved oncologic outcomes and smaller complication rates. We aim to present a case of borderline T3b/T3c renal tumor that was successfully treated in our university center using these techniques.
Left Ventricular Non-compaction Cardiomyopathy - A Case Report
Authors: Timea Szakacs Xantus , Andreea Varga , Elena Bocicor Andreea , Tatar R , Tilea I
Published: August 2015

Background: Left non-compaction cardiomyopathy (LVNC) or “spongy myocardium” is a relatively rare primary genetic cardiomyopathy, characterized by prominent wall trabeculations and intertrabecular recesses which communicate with the ventricular cavity. It appears in isolated form or coexists with other congenital heart diseases and/or systemic abnormalities. Material and method: A 28-year-old woman was admitted with exertional dyspnoea, palpitations, non-specific chest pain and progressive fatigue on exertion. In her family history sudden cardiac-related deaths at young age are present. Cardiovascular system examination revealed tachycardia, intermittent extrabeats. The rest EKG showed sinusal tachycardia (105 bpm), negative T-waves in DII, DIII, aVF, V4-V6. Consecutive 24 hours Holter EKG monitoring revealed nonsustained ventricular tachycardia, paroxysmal atrial fibrillation, isolated ventricular extrasystoles. Echocardiography showed left ventricular systolic dysfunction (LVEF:30-35%), slight LV enlargement, normal right ventricle and small left ventricle (LV) trabeculae in the apical area. Cardiac MRI demonstrated dilated LV and the presence of the trabeculations of LV walls suggestive for non-compaction cardiomyopathy. A combined treatment for heart failure and cardiac arrhythmias was initiated with good clinical results. Patient was scheduled for an implantable cardioverter defibrillator “life-saving”. Conclusions: The symptoms of heart failure and cardiac arrhythmias should be considered important in apparently healthy young patients. Besides intensive medical treatment is indicated the implantation of an ICD “life-saving” and in advanced cases heart transplantation. Even if the electrocardiographic findings are non specific for noncompaction, a complete diagnostic evaluation is important, including sophisticated imaging techniques, a screening of first-degree relatives, and an extensive clinical, and genetic appreciation by a multidisciplinary team.
Laparoscopic Greater Curvature Plication for Morbid Obesity: Indications, Results, Perspectives
Authors: Bara T , Borz C , Suciu A , Denes M , Torok A , Borz B , Marian D
Published: August 2015

Morbid obesity is an important health problem of our century. It is managed by diet, lifestyle changes and medication and surgery. Weight-loss surgery is the most effective treatment for morbid obesity, producing durable weight loss, improvement or remission of comorbid conditions and longer life. Bariatric surgery provides the best results in up to 75% of cases of severe obesity and obesity comorbidities. In the United States, over 200 000 patients benefit every year from bariatric procedures. That means there is a continuous evolving of the bariatric surgery. Bariatric surgery is metabolic surgery because it resolves or alleviates Type2 Diabetes, hyperlipidemia and hypertension. The most employed bariatric operations are Roux -en- Y gastric by-pass, adjustable gastric banding, biliopancreatic diversion and sleeve gastrectomy, each of them having shortage of long term results and safety. In the last eight years was introduced a new bariatric procedure, the gastric plication, in an effort to obtain similar weight loss with lesser complications and costs. We present our initial experience with 30 morbid obese patients who undergone laparoscopic gastric plication in our institution. The mean % Excess Weight Loss was 50% at 6 month and 65% at 12 month with important alleviation of comorbidities. The complications rate was 6.6% for major complications (but only in the first 6 cases) and 10% for minor complications.
Sense of smell and volatile aroma compounds and their role in the evaluation of the quality of products of animal origin – a review
Authors: Gąsior Robert , Wojtycza Krzysztof
Published: August 2015

The aim of this article is to examine how the sense of smell and aroma compounds influence the quality of food of animal origin, and to review gas chromatography-olfactometry methods of volatile substances analysis that can help to promote regional animal products. Smell and smell-inducing compounds play an important role in human life. People have made use of aromatic herbs and spices for ages. The classification of smells was developed by, among others, Aristotle, Linnaeus, Zwaardemaker, as well as Amoore, the creator of the stereochemical theory of olfaction. Smell is also of exceptional importance in a consumer’s evaluation of food quality. Achievements in the area of chromatography, mass spectrometry and olfactometry have contributed to the development of tests for the content of volatile compounds in food materials, e.g. milk, cheese or meat. Analysis of these compounds is more and more often applied to regional products that are commonly characterised by different olfactory properties. The study’s results of raw meat of different animal species show that nutria meat and mutton differ the most from others. Apart from genetic factors, meat composition depends on feeding method, quality and type of fodder, method of cutting, meat seasoning, pH and temperature of processing. Chromatographic and olfactometric tests on animal products, in conjunction with chemometrics, can contribute to the development of reliable characteristics and help to identify the products’ origin. These tests are becoming an inseparable part of the policy of promotion of regional products with specific taste and olfactory properties.