Showing papers in "Defect and Diffusion Forum in 2016"
TL;DR: In this paper, the authors focused on attraction to the worldwide attention of nanotechnology and how this method effects oil breakthrough and improves enhanced oil recovery (EOR) and showed that parameters such as rock types, crude oil types, nanoparticle types, concentrations, and sizes, have significant factors on recovery factor through improving key-parameters such as oil relative permeability, interfacial tension (IFT), wettability, transmissibility and particles retention.
Abstract: Nanotechnology has significant contributions on developing modern industries, such as electronics, biomedical, materials, manufacturing, and energy industry. The changes introduced by nanotechnology, have currently extended to several areas for oil and gas industry, namely exploration, drilling, production, refining and enhanced oil recovery (EOR). This study focuses on attraction to the worldwide attention of nanotechnology and how this method effects oil breakthrough and improves EOR. This Study also implies that parameters such as rock types, crude oil types, nanoparticle types, concentrations, and sizes, have significant factors on recovery factor (RF) through improving key-parameters such as oil relative permeability, interfacial tension (IFT), wettability, transmissibility and particles retention.
33 citations
TL;DR: In this article, a theoretical study of industrial hollow bricks drying in an across flow tunnel dryer is presented, based on the 1st and 2nd laws of Thermodynamic applied to the system.
Abstract: The purpose of this paper is to present a theoretical study of industrial hollow bricks drying in across flow tunnel dryer. The theoretical model is based on the 1st and 2nd laws of Thermodynamic applied to the system. To validate the methodology, numerical and experimental data of the moisture content of the brick during the drying in an industrial scale are compared and a good agreement was obtained. Results of moisture content and temperature of the product and air, and energy and exergy efficiencies are presented and analysed.
10 citations
TL;DR: In this article, the fracture properties of micro-level components of hydrated cement paste are investigated. And the fracture energy and fracture toughness are calculated for individual microstructural phases of cement paste with the aid of nanoindentation, statistical deconvolution and fracture mechanics.
Abstract: This paper deals with fracture properties of microlevel components of hydrated cementpaste. Determination of fracture energy and fracture toughness for quasi-brittle materials hasbecome a challenge for many years on both macro- and micro-scales. Limited number of quantitative data can be found in the literature for the micro-scale. This work uses energetic approach and decomposition of work of indentation into plastic and other parts. Based on simplified assumptions fracture energy and fracture toughness are calculated for individual microstructural phases of cement paste with the aid of nanoindentation, statistical deconvolution and fracture mechanics.
8 citations
TL;DR: In this paper, self-and chemical diffusion coefficients are reported for molten Al-Ag on the Al-rich side of the phase diagram for Ag concentrations of up to 45at% and for pure liquid Ag.
Abstract: Self-and chemical diffusion coefficients are reported for molten Al-Ag on the Al-rich side of the phase diagram for Ag concentrations of up to 45at% and for pure liquid Ag. Temperature dependent Ag self-diffusion coefficients were obtained using quasi-elastic neutron scattering. Chemical diffusion coefficients were measured in situ by means of X-ray radiography of a long-capillary furnace. A detailed error analysis for the long-capillary experiments is reported. It is shown that perturbing effects can be detected and that accurate chemical diffusion coefficients can be measured with high precision. It is demonstrated based on Al-Ag20at% that the Darken equation appears to be valid for this system with a thermodynamic factor lower than unity. Furthermore, in Al-Ag it appears that Ag self-diffusion for small Ag concentrations is faster than Al-self-diffusion in liquid Al. This contrasts with observations made for other Al-based melts like Al-Ni and Al-Cu.
8 citations
TL;DR: This work intends to present a short critical review of several works presented in literature to ensure their performance during the service life and guaranteeing the full performance predicted at the design stage.
Abstract: School buildings energy efficiency is crucial but also environmental, aesthetics, acoustics, accessibility and comfort requirements will be valued. Focus will be on creating value for all the users involved not only in terms of economics, but also in terms of comfort, health, environment, academic success, etc...Various attempts to optimize school buildings design have been made throughout Europe. However, the in-use performance of these buildings revealed very different than the expected. It is crucial to minimize the gap between computer simulation and measured performance. Moreover, the maintenance and operation costs of the recently rehabilitated buildings revealed unaffordable for the limited school budgets. Therefore, cost-effective, high-performing, and minimally invasive solutions should be developed and monitored to ensure their performance during the service life and guaranteeing the full performance predicted at the design stage. This will be achieved by combining innovative construction with real performance information and users’ feedback.This work intends to present a short critical review of several works presented in literature.
8 citations
TL;DR: In this paper, the authors used microwave with and without osmotic dehydration (OD) as a pretreatment for the drying of sweet potato slices and found that OD and higher microwave power carried out to shorter drying time.
Abstract: Drying of sweet potato (Ipomoea batatas (L.)) slices by microwave with and without osmotic dehydration (OD) as a pretreatment was studied. Three osmotic agents (sucrose, sorbitol and fructose) were employed. Drying continued until final moisture content of 20 kg water 100 kg-1 sample. Two different microwave output powers (180 and 350W) were used. The drying kinetics was modeled by mathematical models from the literature. The use of OD and higher microwave power carried out to shorter drying time. Among the tested mathematical models, the Weibull distribution model presented good fitness for drying kinetics obtained in both microwave power.
8 citations
TL;DR: In this paper, the surface properties of TiCN thin films with differing C content were characterized using scanning electron microscopy (SEM), scratch test, mechanical profilometer and ball-on-disc tribometer methods.
Abstract: Titanium carbonitride (TiCN) thin films with differing C content were deposited by cathodic arc evaporation of pure Ti in a gas composite environment of N2 and C2H2. Scanning electron microscopy (SEM), scratch test, mechanical profilometer and “ball-on-disc” tribometer methods were used to characterize the surface, the coefficient of friction (CoF) of the TiCN thin films and the evaluated wear. An increase of the C2H2 fraction in the gas environment leads to a continuous increase in the deposition rate of the TiCN thin films, as well as an increase in the adhesion of the films to the substrate and the values of the CoF. Tribological test results (when tested against Si3N4 balls) show an increase in the friction coefficient of the TiCN from 0.08 to 0.32, with increasing carbon concentration in the film. The CoF decreases rapidly to 0.06 at a C content of 20.6 at.%, N 38.4 at.% and Ti 41.0 at.%.
8 citations
TL;DR: In this paper, the effect of saturated solutions of sodium sulphate and potassium chloride in the capillary absorption curves obtained through partial immersion of red brick samples was investigated and a macroscopic evaluation of the sample's crystallized top surface was obtained after a partial drying period.
Abstract: Rising damp is one of construction’s major problems associated with use of porous materials in this industry. This mechanism has a massive influence on the degradation of historical buildings since they were built in a time when construction technologies made no effort to prevent this kind of pathologies. The rising damp by itself can reduce the aesthetical value of the building and, when combined with the existence of soluble salts in the building and in the ground water can even lead to material decomposition and compromise the structural performance of the building. This happens due to the migration of the salt ions dissolved in water into the porous network of the building’s walls where they remain and crystalize after water evaporates, dealing great pressures against the pore walls and eventually resulting in their fracture after many cycles of crystallization/dissolution.The experimental work intended to study the effect of two different saturated solutions of sodium sulphate and potassium chloride in the capillary absorption curves obtained through the partial immersion of red brick samples. In the end of this paper there will be a macroscopic evaluation of the sample’s crystallized top surface, obtained after a partial drying period. The results revealed significant differences in the capillary coefficients obtained when samples were tested with salt solutions.
8 citations
TL;DR: In this article, the reducibility, durability, and temperatures of a softening and melting of metallurgical iron ore raw materials are studied in vitro via X-ray the structural analysis are carried out.
Abstract: The questions of metallurgical processing of titanium-containing ores are considered. The ores and concentrates of the Kachkanarsky deposit of low-titanous and high-titanous are studied. The reducibility, durability, temperatures of a softening and melting of metallurgical iron ore raw materials are studied in vitro. Via X-ray the structural analysis are carried out. The calculations by means of mathematical models of pyrometallurgical processes are executed. Possibility of the processing of these ores according to schemes is shown: «blast furnace melting − converter melting» and «metallization – electric melting».
7 citations
TL;DR: In this article, the effect of vanadium on the austenite decomposition of a 0.7 %C steel used in railway wheels was analyzed with optical, SEM, TEM and XRD techniques.
Abstract: To understand the effect of vanadium on the austenite decomposition of a 0.7 %C steel used in railway wheels the Continuous Cooling Transformation (CCT) diagrams were obtained and the microstructures analyzed with optical, SEM, TEM and XRD techniques. Vanadium refined the austenitic grain (12 and 6 μm for 7C and 7V, respectively), what can be explain by the presence of fine (10 nm in diameter) V4C3 precipitates, which restricts the austenitic grain growth. In addition, vanadium, in solid solution, reduced the pearlite interlamelar spacing (0.13 and 0.11 μm for 7C and 7V, respectively) by depressing the initial temperature pearlite formation (644 and 639 °C for 7C and 7V, respectively). He increased the ferrite volume fraction from 1 to 3 % at cooling rate of 1 oC/s, due the fact that vanadium is a ferrite stabilizer. Vanadium addition did not affect the initial temperature for martensite formation, but increased the hardenability with martensite formation at slower cooling rates (10 and 5 oC/s for 7C and 7V, respectively). For higher cooling rates (20 to 100 oC/s), the austenite transformation to martensite at room temperature was incomplete and all steels presented martensite and retained austenite, which volumetric fraction was near the same for both steels varying from 20 to 40 %.
6 citations
TL;DR: In this article, a new method has been proposed for determining very fine machining uniformity over the elaborated surface and could be applied to different machined materials and machining procedures.
Abstract: In the paper a new method has been proposed for the determining of the very fine machining uniformity over the elaborated surface and could be applied to different machined materials and machining procedures. The proposed methodology is relatively simple and is essentially formulated in the few subsequent steps: taking surface roughness 3D profile accordingly proposed scheme; estimation of the roughness statistical parameters: Rp, Rv, Rt, Ra, Rq, Rskew, Rkurt, and if need be – surface rugosity Ru; calculation of the centroid of the obtained data due to the measurement fields, calculation of the barycentre of the obtained data with the weighting variable chosen for the appropriate evaluation of the surface machining uniformity. As the main Cartesian coordinates of the centroid calculation we propose (Rskew, Rkurt), although other data organization schemes have also been provided as the example solutions. The final evaluation of the surface machining uniformity is based upon the Euclidean distance between the centroid and barycentre of the surface roughness data. The proposed method has been applied to experimental results obtained with the AFM technique used on samples of the polished AZ31 magnesium alloy. The surface machining procedure comprised of four stages performed with using different abrasive media, finally lead to the highest grade of the surface roughness.
TL;DR: In this article, the authors present data on the water sorption of polymer composites having thermoset and thermoplastic matrices as a function of vegetable fiber identity, content and hybridization with glass fibers.
Abstract: Despite the ever-growing worldwide interest in the use of lignocellulosic fibers as reinforcement in either thermoset or thermoplastic matrices, the use of these fibers to replace synthetic ones, is limited. The reasons for these limitations are associated with the vegetable fiber’s heterogeneity, lower compatibility to most polymers, inferior durability, flammability, poorer mechanical properties and higher moisture absorption when compared with synthetic fibers. Nevertheless, despite these drawbacks, vegetable fiber reinforced polymer composites are lighter in weight, more sustainable and can be used for non-structural products. Strategies to minimize these drawbacks include fiber and or matrix modification, the use of compatibilizers, fiber drying and the concomitant use of vegetable and synthetic fibers, for the production of hybrid composites, the latter being an unquestionable way to increment overall mechanical and thermal properties of these hybrid systems. Here we present data on the water sorption of polymer composites having thermoset and thermoplastic matrices as a function of vegetable fiber identity, content and hybridization with glass fibers. Our data indicates that, regardless if the matrix is a thermoset of a thermoplastic, water absorption tends to be relatively independent of vegetable fiber identity and to be significantly dependent of its content. Fiber drying prior to composite manufacturing and hybridization with glass fibers leads to lower overall water absorption and higher mechanical properties.
TL;DR: In this article, the prediction of the interfacial heat transfer coefficient during the horizontal directional solidification of an Al-3wt.%Cu alloy on water cooled stainless steel chill under transient heat flow conditions is presented.
Abstract: This paper presents a theoretical-experimental study for the prediction of the interfacial heat transfer coefficient during the horizontal directional solidification of an Al-3wt.%Cu alloy on water cooled stainless steel chill under transient heat flow conditions. Eight thermocouples were connected with the casting and the time-temperature data were recorded automatically. The thermocouples were placed at 5, 10, 15, 20, 30, 50, 70 and 90 mm from the metal-mold interface. A numerical technique which compares theoretical and experimental thermal profiles was used to measure the heat transfer coefficient values. This has permitted the evaluation of the variation of this thermal parameter along the solidification which is represented by a power equation that shows the time dependence during the process given by hi = constant (t)-n, which represents the best fit between the experimental and calculated curves. The obtained results also include the variation of both primary and secondary dendritic arm spacings of alloy analyzed as a function of heat transfer coefficient. These dendrite arm spacings were found to decrease as the values of this coefficient are increased. Finally, an experimental law of the Hall-Petch type is proposed relating the resulting microhardness to the heat transfer coefficient investigated.
TL;DR: In this paper, the authors have measured HF gas transport coefficients for different FOUP polymers, based on Fick's law, for thin films of polycarbonate (PC), polyetherimide (PEI) and a low absorbing polymer named Entegris Barrier Material (EBM) that constitute FOUPs.
Abstract: In order to better understand the sorption and outgassing mechanism of gases in relation to wafers containers (FOUP), we have measured HF gas transport coefficients for different FOUP polymers. Gas sorption is governed by surface adsorption, followed by diffusion and solubility. Cross contamination between FOUP and wafer occurs when polymers outgas contaminants into the surrounding environment. Diffusion is the key parameter to understanding cross contamination within the FOUP environment. In this work, we present the transport coefficients obtained for gaseous HF at cleanroom conditions (Patm, 21 ± 2°C & 40% RH) using the sorption kinetic method, based on Fick’s law, for thin films (<80μm) of polycarbonate (PC), polyetherimide (PEI) and a low absorbing polymer named Entegris Barrier Material (EBM) that constitute FOUPs. The resulting kinetic curves show Fick’s behavior, where obtained HF diffusion coefficients are between 3.7 X10-10 and 42 x10-12 cm2/s and are significantly lower than diffusion coefficients obtained for H2O using a gas permeation method. Nevertheless, the similar order of magnitude between the HF and the H2O permeability coefficients obtained by the two methods validates the sorption kinetic method. Finally, the obtained coefficients were used in numerical simulation in order to forecast polymer behavior.
TL;DR: In this article, the influence of Spark Plasma Sintering and field assisted sintering technology on the interfacial reactions in Al - Fe - Al stacks was investigated at temperatures between 500°C and 600°C.
Abstract: The influence of Spark Plasma Sintering / Field Assisted Sintering Technology applying pulsed direct current up to the root-mean-square current densities of 129 A/cm2 on the interfacial reactions in Al - Fe - Al stacks was investigated at temperatures between 500°C and 600°C. Independently of the current density and current direction, thin Al13Fe4 and wide Al5Fe2 phases were detected in the diffusion couples. The Al5Fe2 phase consisted of columnar grains having a {001}-fiber texture. Al13Fe4 was found in the form of discontinuous spots at the Al/Al5Fe2 interface. The interface between Al5Fe2 and Fe was highly fringed. The layer growth kinetics of Al5Fe2 was parabolic. The growth rate was strongly enhanced in the SPS/FAST experiments as compared to the conventional diffusion experiments, independently, on the current direction. It is suggested that the enhanced growth rates are a result of temperature gradients existing in a typical Spark Plasma Sintering device. Possible effects of thermomigration and electromigration are discussed.
TL;DR: In this article, Dyed polyester samples by using different dyestuffs were examined with the polarized light with the help of optical light microscopy, and the relationship between dichroism and the concentration of dyestuff was examined.
Abstract: The identification and measuring of geometrical dimensions of very small objects including textile is the biggest achievement of the image processing techniques. Not only the analysis of the basic structure of yarn like hairiness, thickness and number of twist but also the external structural analysis like twist parameters and linear density co-efficient is possible with outstanding approach of image analysis new techniques. Dyed polyester samples by using different dyestuffs were examined with the polarized light with the help of optical light microscopy. It was observed that the dyestuffs possess strong dichroism and the relationship between dichroism and the concentration of dyestuff was examined. Dark field and Bright field illuminations together with imaging polarimetry are compared in terms of depth of field tolerance and image quality. Experiments show that passive imaging polarimetry illumination is superior in terms of depth of field tolerance and contrast allowing significant improvement of textile structure investigation.
TL;DR: In this article, the effect of radiation crosslinking on the tensile strength and elongation of polyamide was examined in dependence on the dosage of the ionizing electron beam radiation (non-irradiated samples and those irradiated by dosage 66 and 132 kGy were compared) and on the test temperature (23, 50, 80, and 110 oC).
Abstract: It was found in this study, that radiation crosslinking has a positive effect on the mechanical properties of selected type polyamide. In recent years, there have been increasing requirements for quality and cost effectiveness of manufactured products in all areas of industrial production. These requirements are best met with the polymeric materials, which have many advantages in comparison to traditional materials. The main advantages of polymer materials are especially in their ease of processability, availability, and price of the raw materials. Radiation crosslinking is one of the ways to give the conventional plastics mechanical, thermal, and chemical properties of expensive and highly resistant construction polymers. The main purpose of this paper has been to determine the effect of radiation crosslinking on the tensile strength and elongation of PA 66 (filled with 30 % glass fibers). These properties were examined in dependence on the dosage of the ionizing electron beam radiation (non-irradiated samples and those irradiated by dosage 66 and 132 kGy were compared) and on the test temperature (23, 50, 80, and 110 oC). Radiation cross-linking of PA 66 results in increased mechanical strength, and decreased of elongation. As an addition, the increased surface microhardness of polyamide was found.
TL;DR: In this article, an experimental drying procedure of rough rice grains (BRSMG CONAI variety) was reported and the results were compared with simulated data by means of the liquid diffusion model equilibrium boundary condition.
Abstract: Simulate the rice drying process at specific drying conditions is of great interest to optimize the process and ensure a better quality of the final product. In the present work, experimental drying procedures of rough rice grains (BRSMG CONAI variety) was reported and drying kinetic was obtained at temperature using 40°C. The results were compared with simulated data by means of the liquid diffusion model equilibrium boundary condition. The geometry used to represent the rice grain was prolate spheroid. For this purpose, the diffusion equation, written in cylindrical coordinates, and solved via Galerkin-based integral method considering the constant diffusion coefficient. A good agreement was observed between predicted and experimental data. It was also possible to observe that the highest moisture gradients occur at the tip of the grain, which is region more affected by thermal and hydric stresses. The studied model can be used to solve problems involving diffusion processes, such as: drying, wetting, heating and cooling, provided that the geometrical shape of the body is similar to prolate spheroid.
TL;DR: In this article, the influence of high temperature exposure on the mechanical and wear properties of selected HVOF sprayed CrC and No/Co-based alloy coatings were tested.
Abstract: The influence of high temperature exposure on the mechanical and wear properties of selected HVOF sprayed CrC and No/Co – based alloy coatings were tested. Comparison of as-sprayed and 600°C/116 h annealed coatings’ microhardness, cohesive strength, abrasive and adhesive wear resistance showed that the Co-based Stellite 6 coating’s wear properties were deteriorated by heat exlosure despite of the increase of its hardness and cohesive strength. The heat exposure was found to be beneficial for both mechanical and wear properties of NiCrBSi self-fluxing coating. On the contrary, mechanical properties of Cr3C2-NiCr coating slightly decreased, while its wear resistance slightly increased as a result of high temperature exposure.
TL;DR: In this article, the authors evaluated the mechanical characterization and water sorption of polymer matrix composites reinforced with sisal fibers at different bath temperatures and found that for higher water temperature less time the sample takes to reach saturation and mechanical properties is reduced.
Abstract: In this work we evaluated the mechanical characterization and sorption water of polymer matrix composites reinforced with sisal fibers at different bath temperatures. Experimental tests of tensile (ASTM D 3039), impact (ASTM D 256) and water sorption in samples with rectangular cross section (dimensions of specimens 20x20mm) were made. It was used the unsaturated polyester resin matrix (Resapol 10-316). With the aim of analyzing the tensile strength and the impact, samples were made with fiber content (by weight) of 44.6%. Water sorption tests were performed with the specimens immersed in water at 25°C, 50°C and 70°C. The results showed that for higher water temperature less time the sample takes to reach saturation and mechanical properties is reduced.
TL;DR: In this paper, an appropriate modification of a surface of the additional element with regard to a mutual interaction, surface microstructure and mechanical properties of the resulting composite part was also found.
Abstract: The global development of carbon composite materials has been devoting constantly in still more companies and research institutions. Pre-saturated fabrics known as prepregs have a significant position in this field. The common problem of many worldwide authors is how to determine their tensile strength. The problem with tensile load is mainly due to the extremely high strength of fibers filaments and structural fragility of the thin width of formed profiles. Therefore, indirect methods are usually used. They are based on a determination of the resonant frequencies or on a conversion of values obtained e.g. with bending test. In our case, some experiments have been based on the idea of added a non-composite material into the final structure. The aim of this work was also to find an appropriate modification of a surface of the additional element with regard to a mutual interaction, surface microstructure and mechanical properties of the resulting composite part.
TL;DR: In this paper, a consistency between the Darken method and the Onsager representation for cross diffusion in multicomponent system is shown by defining new sets of forces and fluxes linearly interrelated by a symmetric matrix of phenomenological coefficients.
Abstract: A consistency between the Darken method and the Onsager representation for cross diffusion in multicomponent system is shown. The justification is made by defining new sets of forces and fluxes linearly interrelated by a symmetric matrix of phenomenological coefficients. For the first time, the system of the components having various molar volumes is treated in this way. It is shown that the transformation leaves the entropy production unchanged. As an example, the entropy production for interdiffusion in the ternary Co-Fe-Ni diffusion couple is calculated and compared with mixing entropy.
TL;DR: In this paper, a continuous-flow DNA amplification device is presented, which employs a serpentine polydimethylsiloxane microchannel, a glass cover with micro heaters and sensors, and a cooling polymethylmethacrylate channel.
Abstract: Since polymerase chain reaction (PCR) was invented, it has become one of the most significant approaches for generic identification during the last few decades. PCR is a useful procedure to magnify the number of copies of a specific DNA template exponentially. Integrated microfluidic DNA amplification devices that employ a serpentine polydimethylsiloxane microchannel, a glass cover with micro heaters and sensors, and a cooling polymethylmethacrylate channel are demonstrated in the present study. With the aid of commercial computational fluid dynamics software, we design the continuous-flow DNA amplification device. The influences of various chip materials, water cooling conditions and geometric parameters on the temperatures of the chip are expressed. Using the MEMS process, two micro aluminum heaters and sensors are fabricated. This device represents the first demonstration of Al heaters and sensors integrated in continuous-flow PCR microfluidics. The LabVIEW control module is used to manage the temperatures of the micro-domain heating. One important feature of this system is the temperature of the annealing zone is controlled by the flow rate of the fluid inside a water channel under the glass chip. The cooling channel cannot only provide great thermal insulation between two temperature zones at the opposite sides of the chip, but also improve the temperature uniformity at the chip center temperature zone. By utilizing an IR thermometer, the images of the surface temperature distributions are captured to show the effects of the employed microheaters and the cooling channel on the thermal field of the PCR device. Finally, we find the temperature regions generated in the present device are suitable for completing the PCR process.
TL;DR: In this paper, the microstructure evolution during the continuous heating of a cold-rolled Al-Mg-Si alloy was analyzed using dilatometry, differential scanning calcorimetry, X-ray diffraction and microhardness measurement.
Abstract: In contrast to isothermal aging, few reports document the non-isothermal aging of deformed Al–Mg–Si alloys. The knowledge of non-isothermal aging of pre-deformed Al–Mg–Si alloys is of primary importance to understand the thermal stability as well as to control the microstructure of the final product during industrial processing. Therefore, the present work has been focused to understand the microstructure evolution during the continuous heating of a cold rolled Al–Mg–Si alloy. This has been followed using dilatometry, Differential Scanning Calorimetry, X-Ray Diffraction and microhardness measurement. Based on the results obtained, it is shown that dilatometry is a powerful tool to study phase transformations in deformed Al-Mg-Si alloys, moreover, the microstructural evolution, of the cold rolled sample, can be described as follows: at the earlier stages of the non-isothermal aging, formation and then the reversion of fully coherent GP zones take place. This is followed by the simultaneous occurrence of β” and β’ precipitation and recovery reaction. By continuing aging, the next reactions which will take place are β” and β’ dissolution and recrystallization. Finally, one can observe the formation and then the dissolution of the equilibrium phase β.
TL;DR: In this article, an operating activity and thermal performance measurement of pulsating heat pipe (PHP) was performed with PHP made from glass and two types of PHPs were made.
Abstract: Heat pipe is well known device which is used to heat transfer phase-change of working fluid. Pulsating heat pipe (PHP) is special type of heat pipe which heat transfer by pulsating movement of working fluid. Article deals about operating activity and thermal performance measurement of this special heat pipe. Operating activity visualization of PHP was performed with PHP made from glass. The two types of PHPs were made. The first PHP has internal diameter of tube 1 mm, second PHP has internal diameter of tube 1.5 mm and both PHPs have eleven meanders. The working fluids used in PHP were water and Fluorinert FC-72. These fluids were chose for their different thermo-physical properties and the visualization observe formation of liquid and vapour phase working fluid during filling process and working operation.Next, the article describes thermal performance measurement of PHP depending on working fluid amount and heat source temperature. Measurement was performed with PHP made from copper tube with inner diameter 1.5 mm curved to the twenty one meanders and filled with water. The results give us image about formation and distribution of working fluid in pulsating heat pipe and about influence of working fluid amount on the heat transfer ability of pulsating heat pipe.
TL;DR: In this article, the authors showed that grain boundary (GB) diffusion kinetic is the same in micro-and nanoGBs, whereas triple junction (TJ) diffusion is several orders of magnitude faster than GB diffusion.
Abstract: Ge and B diffusion was studied in nanocrystalline Si, and Pd and Si self-diffusion was studied in nanocrystalline Pd2Si during and after Pd/Si reactive diffusion. These experiments showed that grain boundary (GB) diffusion kinetic is the same in micro-and nanoGBs, whereas triple junction (TJ) diffusion is several orders of magnitude faster than GB diffusion. In addition, GB segregation and GB migration can significantly modify atomic diffusion profiles in nanocrystalline materials, and atomic transport kinetics can be largely increased in nanograins compared to micro-grains, as well as during reactive diffusion, probably due to an increase of point defect concentration. These observations show that atomic transport in nanometric layers during reactive diffusion is complex, since GBs and TJs are moving and the proportion of GBs and TJs is changing during the layer growth.
TL;DR: In this paper, a two-dimensional model based on mass conservation equations, linear momentum and the model k-e standard turbulence was adopted to study the leakage of behavior in a submerged pipeline carrying oil.
Abstract: Oil spill at sea by pipeline cracks can cause environmental damage. Knowledge of interfacial phenomena of immiscible liquids helps to study the dispersion of pollutants in oceans, favoring thus flow behavior of the forecast in the vicinity of the leak in submerged pipelines. This study aims to numerically study the leakage of behavior in a submerged pipeline carrying oil. It adopted a two-dimensional model based on mass conservation equations, linear momentum and the model k-e standard turbulence. We used the Ansys CFX for meshing with 40,510 hexahedral elements. The results of pressure fields and volumetric fraction of oil are analyzed and discussed.
TL;DR: In this paper, the authors compared the results of temperature dependences of thermal conductivity for three newly designed concretes, namely in the context of their compressive strength, in order to evaluate their thermal insulation properties.
Abstract: The aim of the publication is the comparative measurements of changes in temperature of the significant material coefficient - thermal conductivity for newly developed construction materials (lightweight concrete). The aim is met by using a newly proposed method and a newly developed device by the approximation modelling of the temperature dependence of the thermal conductivity coefficient of the new composites and also the interpretation of measurement results in the context of optimally desired characteristics of thermal insulation concrete. Construction materials for residential buildings should have good thermal insulation properties, i.e. relatively low coefficients of thermal conductivity. With regard to the relatively most important property of concrete – strength, however, the reduction in thermal conductivity of concrete is limited. Thermal conductivity of concrete can be reduced very effectively by increasing its porosity; on the other hand, by increasing the porosity, the strength of concrete is significantly reduced. The publication, therefore, compares the results of temperature dependences of thermal conductivity for three newly designed concretes, namely in the context of their compressive strength.
TL;DR: The Ti-6Al-4V alloy was oxidized isothermally and cyclically in air, and its oxidation behavior was compared with that of Ti metal as discussed by the authors.
Abstract: The Ti-6Al-4V alloy was oxidized isothermally and cyclically in air, and its oxidation behavior was compared with that of Ti metal. The isothermal oxidation at 800°C indicated that Ti-6Al-4V and Ti oxidized fast almost linearly, and the oxide scales that formed on Ti-6Al-4V and Ti were non-adherent. The cyclic oxidation indicated that Ti-6Al-4V oxidized faster than Ti at 600°C, and serious scale spallation occurred in Ti-6Al-4V compared to Ti at 800°C. The oxide scales that formed on Ti-6Al-4V and Ti after cyclic oxidation at 800°C delaminated into several pieces owing to excessive stress aroused by the repetitive thermal shock.
TL;DR: In this article, the tribological properties of magnetron sputtered amorphous silicon carbide (a-SiC) and silicon carbonitride coatings with thickness of 2.2 and 3.4 µm were investigated.
Abstract: The tribological properties of magnetron sputtered amorphous silicon carbide (a-SiC) and silicon carbonitride coatings (a-SiCN) with thickness of 2.2 and 3.4 µm were investigated. Samples were additionally annealed at temperature of 700°C or 900°C in air. Progressive load scratch tests were performed on the annealed samples as well as on the as deposited ones. An acoustic emission signal was detected during all tests using the sample holder with embedded sensor of our own design. Results indicate no change in wear resistance of SiCN sample after high temperature exposure up to 900°C, unlike in the tests of SiC coatings. Detection of acoustic emission generated during the scratch test proved to be a significant improvement for the coating evaluation.