Showing papers in "Materials Science in 2012"
TL;DR: In this article, the structure and surface morphology of the as-deposited Al films were studied using scanning electron microscopy (SEM) and atomic force microscopy, showing that the mean grain size of thin Al films on all of the substrates increased from 20nm-30nm to 50nm-70nm with increase of the deposition rate.
Abstract: Aluminum (Al) films with thickness of 100 nm were grown on unheated glass, silicon and mica substrates by electron beam evaporation. The deposition rates were adjusted in the range between 0.1 nm/s and 2 nm/s, the pressure in the vacuum chamber during deposition was lower than 1·10 –3 Pa. The structure and surface morphology of the as-deposited Al films were studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM). SEM imaging of the films showed that the mean grain size of thin Al films on all of the substrates increased from 20 nm – 30 nm to 50 nm – 70 nm with increase of the deposition rate. Quantitative AFM characterization showed that for all substrates the root mean square surface roughness increases monotonically with increasing the deposition rate from 0.1 nm/s to 2 nm/s. The observed effects of the deposition rate on the grain size and surface roughness are explained by the fundamental characteristics of the island growth mode, the influence of the background gases and the surface morphology of the bare substrates. DOI: http://dx.doi.org/10.5755/j01.ms.18.4.3088
73 citations
TL;DR: In this paper, the role of hydrogen in the production of commercially pure titanium by the method of pressing and sintering of titanium and titanium-hydride powders was investigated, and it was shown that the changes in the mechanical properties under the conditions of hydrogenation of the material determine the formation of a specific fine-porous microstructure in the case of pressing of a hydrated powder.
Abstract: We perform the experimental investigation the role of hydrogen in the production of samples of commercially pure titanium by the method of pressing and sintering of titanium and titanium-hydride powders. The comparative analysis of their behavior shows that the changes in the mechanical properties under the conditions of hydrogenation of the material determine the formation of a specific fine-porous microstructure in the case of pressing of a hydrated powder. As an important specific feature of hydrated titanium as compared with the titanium powder, we can mention its dehydrogenation in the process of heating, which leads to the activation of sintering, decreases the oxygen content of the final material, and, hence, improves the mechanical characteristics of sintered commercially pure titanium.
48 citations
TL;DR: In this paper, a light-weight sandwich panel for trailers was designed using vacuum infusion technology and a 2D finite element analysis (FEA) of 4-point bending was made with ANSYS APDL (Classic) software.
Abstract: The purpose of this study was to design a light-weight sandwich panel for trailers. Strength calculations and selection of different materials were carried out in order to find a new solution for this specific application. The sandwich materials were fabricated using vacuum infusion technology. The different types of sandwich composite panels were tested in 4-point bending conditions according to ASTM C393/C393M. Virtual testing was performed by use of ANSYS software to simplify the core material selection process and to design the layers. 2D Finite element analysis (FEA) of 4-point bending was made with ANSYS APDL (Classic) software. Data for the FEA was obtained from the tensile tests of glass fiber plastic (GFRP) laminates. Virtual 2D results were compared with real 4-point bending tests. 3D FEA was applied to virtually test the selected sandwich structure in real working conditions. Based on FEA results the Pareto optimality concept has been applied and optimal solutions determined.
46 citations
TL;DR: In this paper, the thermal expansion and thermal conductivity of hybrid composites with various graphite contents (5.0, 7.5, 10 wt.%) and different silicon carbide particle sizes (45 µm and 53 µm) were investigated.
Abstract: Aluminum-silicon based hybrid composites reinforced with silicon carbide and graphite particles were prepared by liquid phase particle mixing (melt stirring) and squeeze casting. The thermal expansion and thermal conductivity behaviors of hybrid composites with various graphite contents (5.0; 7.5; 10 wt.%) and different silicon carbide particle sizes (45 µm and 53 µm) were investigated. Results indicated that increasing the graphite content improved the dimensional stability, and there was no obvious variation between the thermal expansion behaviors of the 45 µm and the 53 µm silicon carbide reinforced composites. The thermal conductivity of hybrid composites was reduced due to the enrichment of the graphite component.
45 citations
TL;DR: In this article, the effect of treatment variables such as amount of mordant, time and temperature on the color strength of dyed fibers was examined and the fastness properties of dyed wool against washing, light and wet rubbing were evaluated.
Abstract: In this study, Berberine colorant extracted from berberis vulgaris root was applied on wool fiber using alum (aluminum potassium sulfate), copper sulfate and potassium dichromate as mordant. The effect of treatment variables such as amount of mordant, time and temperature on the color strength of dyed fibers was examined. The fastness properties of dyed wool against washing, light and wet rubbing were evaluated. the use of metal mordants increased the color strength of the dyed goods. Increase in dyeing time and temperature caused deeper shades. All mordants, increased the rub fastness and wash fastness of dyed samples, but the light fastness was increased except in case of alum. Berberine is a cationic dye and because of it's quaternary ammonium structure can act as an antibacterial agent. So, dyed samples were tested for antibacterial activity using AATCC test method 100-2004. The dyed wool represented a high level of antibacterial activity. The extract of the berberis vulgaris can be considered as a natural dye of acceptable fastness properties together with excellent antibacterial activity for woolen textiles. DOI: http://dx.doi.org/10.5755/j01.ms.18.3.2437
33 citations
TL;DR: In this article, the authors discuss the importance of sport, sportification, and women's empowerment in the field of fiziologinis, and conclude that sportification is important for women's health.
Abstract: Sportui ir aktyviam laisvalaikiui skirti drabužiai turi tenkinti ne tik estetinius, bet ir komforto reikalavimus. Dėvint tokio tipo drabužius gali būti skiriamas jutiminis, fiziologinis ir terminis komfortas. Jutiminis komfortas lemia drabužį dėvincio žmogaus savijautą aktyviai judant. Fiziologinis komfortas lemia žmogaus organizmo būkle aktyvios fizinės veiklos metu. Jei drabužis ilgą laiką lieka drėgnas, nustojus aktyviai judėti juntamas saltis, kyla grėsmė persalti. Terminis komfortas lemia silumos ir salcio, drėgnumo ir sausumo pojūtį. Tirti dvisluoksniai skersiniai mezginiai, numegzti is natūralios kilmės verpalų (medvilninių ir bambukinių) ir sintetinių siūlų (PES, Coolmax, PA, PP) derinio lygiuoju sluoksniuotuoju bei kombinuotaisiais pynimais. Sio tyrimo tikslas – nustatyti sių mezginių siluminių savybių, tai yra siluminio laidumo bei siluminės varžos, priklausomybe nuo mezginio pynimo ir pluostinės sudėties. Tyrimo metu nustatyta, kad mezginių, numegztų is bambukinių verpalų ir sintetinių siūlų derinio, siluminis laidumas yra mažesnis nei mezginių, numegztų tokiu paciu pynimu is medvilninių verpalų ir atitinkamų sintetinių siūlų derinio. Didėjant kilpos ilgiui, siluminis laidumas taip pat didėja, t. y. mažesnio kilpų tankumo mezginiai suteikia vartotojui vėsumo pojūtį. Siluminė varža, priesingai, labiau priklauso nuo sintetinių siūlų tipo nei nuo natūralios kilmės verpalo. Kombinuotaisiais pynimais megztų mezginių siluminė varža dėl didesnio mezginio storio yra didesnė nei sluoksniuotaisiais pynimais megztų mezginių. DOI: http://dx.doi.org/10.5755/j01.ms.18.2.1921
32 citations
TL;DR: In this article, the tribological behavior of combined metaloxide-ceramic layers synthesized on electric-arc coatings sprayed from solid electrode wires in couples with steel and bronze riders placed in a commercial diesel mineral oil with and without adding insignificant amounts of glycerol.
Abstract: We study the tribological behavior of combined metal-oxide–ceramic layers synthesized on electric-arc coatings sprayed from solid electrode wires in couples with steel and bronze riders placed in a commercial diesel mineral oil with and without adding insignificant amounts of glycerol. It is shown that the efficiency of the lubricating mixture is independent of the concentration of glycerol, which participates solely in the chemical transformations realized under the conditions of friction interaction.
31 citations
TL;DR: In this article, the surface roughness impact on adhesion properties was evaluated on dried ash ( Fraxinus excelsior L. ) and birch ( Betula L.4. ) wood.
Abstract: For the evaluation of surface roughness impact on adhesion properties, the samples of dried ash ( Fraxinus excelsior L. ) and birch ( Betula L. ) wood were used. Before wood finishing, the surfaces of the samples were sanded. In order to get different surface roughness the abrasive material of P80, P120, P150, P180, P220 and P240 grit was used. The parameters of surface roughness R a , R z and R max were measured in three directions: along the wood grain, across the grain and in the angle of 45o. Comparison of the results showed the non-linear dependency of roughness parameters. Afterwards the wood surface was coated with three different acrylic-polyurethane coating systems (1 layer of varnish without primer, 1 layer of primer and 1 layer of varnish, and 1 layer of primer and 2 layers of varnish). The adhesion strength was assessed using the pull-off method. Also the nature of the fracture was evaluated. It was determined that the peculiarities of surface roughness, coating system type and wood species signally results the values of the adhesion strength. DOI: http://dx.doi.org/10.5755/j01.ms.18.4.3094
30 citations
TL;DR: In this article, the fatigue properties of specimens with different notches made of FeP04 steel are presented, characterized by double symmetric lateral notches with radius of the notch root ranging from ρ 0.2 to 10mm.
Abstract: Fatigue properties of specimens with different notches made of FeP04 steel are presented. The specimens are characterized by double symmetric lateral notches with radius of the notch root ranging from ρ = 0.2 to 10 mm. An MTS 809 servohydraulic device was used for the tests. All fatigue tests were performed under force control by imposing a constant value of the nominal load ratio (R = 0) and a load amplitude P
a
= 6 kN for the notch root ρ = 0.2 mm and 7 kN for the notch roots ρ = 1.25, 2.5 and 10 mm. The test frequency varied from 13 to 15 Hz. During the tests performed under constant loading, we observe the fatigue weakening of the material and an increase in strain.
29 citations
TL;DR: In this paper, the residual lifetime of the section of the Urengoi-Pomary-Uzhgorod main gas pipeline with regard for hydrogenation of the pipeline wall was evaluated.
Abstract: The soil environment of an emergency section of a main gas pipeline is characterized as “near-neutral” (pH < 8) with middle or, in some cases, even high (more than 0.3 mm/year) corrosion activity and can be modeled by the NS4 solution. Long-term operation (23 years) decreases mainly the static crack resistance of X60 and X70 steels, whereas hydrogenation under the potential of cathodic protection sharply increases their susceptibility to stress corrosion fracture under both static and cyclic loading. The X70 steel is more sensitive to the negative influence of operation and hydrogenation as compared with X60 steel. We have evaluated the residual lifetime of the section of the “Urengoi–Pomary–Uzhgorod” main gas pipeline with regard for hydrogenation of the pipeline wall.
29 citations
TL;DR: In this article, the effect of different post-cure parameters to a polymer matrix particulate reinforced composite material was examined, and it was shown that the material should be cured at 60 °C - 80 °C.
Abstract: This study examines the effect of different post cure parameters to a polymer matrix particulate reinforced composite material. The goal is to evaluate the importance of different factors and to suggest a well-balanced post cure mode that supports the application of the material. Polymer matrix composites are post cured at elevated temperature to increase the amount of cross linking to achieve better chemical and heat resistance and mechanical properties. Every material has an individual post cure process that depends from the raw materials. Post curing variables include temperature, duration of cure, the time between initial curing and post curing and temperature profile gradient. There are several ways to determine the cure state of a polymer. It can be evaluated based on the mechanical and physical properties, residual styrene content, glass transition temperature, residual exotherm or solvent swelling test. For the determination of the suitable post cure parameters test slabs were casted and post cured with varying time and temperature. Glass transition temperature, residual exotherm, softening in ethanol, surface hardness, flexural strength and flexural modulus were determined. It is shown that the material should be cured at 60 °C – 80 °C. With higher temperature and extended time of cure the glass transition temperature raises but the material becomes too brittle. DOI: http://dx.doi.org/10.5755/j01.ms.18.3.2435
TL;DR: In this paper, repeated induction heating and quenching of AISI E52100 is proposed, and the refinement of the martensite structure and consequent improvement of the fatigue properties measured by rotating bending fatigue tests of steel parts is reported.
Abstract: Martensitic high-carbon high-strength AISI E52100 steel (JIS SUJ2) is one of the main alloys used in rolling contact applications when high wear and fatigue resistance are required. In this work, repeated induction heating and quenching of AISI E52100 is proposed, and the refinement of the martensite structure and consequent improvement of the fatigue properties measured by rotating bending fatigue tests of steel parts is reported.
TL;DR: In this article, the authors propose a misinių technologinė's savybės: sutankinamumas, pralaidumas orui, gniuždomasis stipris, buvo nustatomos formavimo misiniǫs aparatu LRuE-2e.
Abstract: Straipsnyje pateikti liejininkystėje formavimo smėliui suristi naudojamų kalcio bentonitų, aktyvintų natrio karbonatu ir veikiamų aukstų temperatūrų, tyrimų rezultatai. Tyrimai buvo atliekami taikant infraraudonosios spektroskopijos (FTIR) ir rentgeno (XRD) analizės metodus. Monmorilonito kiekis bentonito bandiniuose buvo nustatomas siuolaikiniu kompleksiniu Cu(II)-TET metodu. Formavimo misinių technologinės savybės: sutankinamumas, pralaidumas orui, gniuždomasis stipris, buvo nustatomos formavimo misinių analizės aparatu LRuE-2e. DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1342
TL;DR: In this article, the effect of FSW process on the tensile properties of the AA2124/SiC/25p metal matrix composite (MMC) plates was defined and the application of decision tree technique was performed to predict tensile property of MMC plates.
Abstract: Friction stir welding (FSW) is a relatively contemporary solid state welding process and has been employed in aerospace, railway, automotive and marine industries for joining of aluminum, magnesium, zinc, titanium, copper alloys, dissimilar metals and thermoplastics. The FSW process parameters such as tool rotation speed, tool traverse speed and tilt angle play an important role in deciding the joining quality. The present study defines the effect of FSW process on the tensile properties of the AA2124/SiC/25p metal matrix composite (MMC) plates. Obtained results showed that the joint efficiency decreases by increasing the tool traverse speed while tool rotation speed was kept constant. Second contribution of this study is the application of decision tree technique to predict the tensile properties of friction stir welded MMC plates. It is seen that methodology can be applied with great accuracy. DOI: http://dx.doi.org/10.5755/j01.ms.18.4.3092
TL;DR: In this paper, a combination of different analytical techniques (light microscopy upon black-white and colour etching, scanning electron microscopy (SEM) upon deep etching and energy dispersive X-ray analysis (EDX)) were used for the identification of the various phases.
Abstract: The contribution describes influence of the age-hardening consist of solution treatment at 515 °C with holding time 4 hours, water quenching at 40 °C and artificial aging at different temperature 150 °C, 170 °C and 190 °C with different holding time 2, 4, 8, 16 and 32 hours on mechanical properties (tensile strength and Brinell hardness) and changes in morphology of eutectic Si, Fe-rich and Cu-rich intermetallic phases in secondary (recycled) AlSi9Cu3 cast alloy. A combination of different analytical techniques (light microscopy upon black-white and colour etching, scanning electron microscopy (SEM) upon deep etching and energy dispersive X-ray analysis (EDX)) were therefore been used for the identification of the various phases. Quantitative study of changes in morphology of eutectic Si, Cu-rich and Fe-rich phases was carried out using Image Analyzer software NIS-Elements. Mechanical properties were measured in line with EN ISO. Age-hardening led to changes in microstructure include the spheroidization and coarsening of eutectic silicon, gradual disintegration, shortening and thinning of Fe- rich intermetallic phases, the dissolution of precipitates and the precipitation of finer hardening phase (Al 2 Cu) further increase in the hardness and tensile strength in the alloy. DOI: http://dx.doi.org/10.5755/j01.ms.18.3.2430
TL;DR: In this paper, the authors developed a method for the numerical evaluation of the total influence of correction and wear of the teeth on the service life of cylindrical gears and contact stresses.
Abstract: We developed a method for the numerical evaluation of the total influence of correction and wear of the teeth on the service life of cylindrical gears and contact stresses. The results of numerical calculations make it possible to establish the qualitative and quantitative regularities of the influence of both structural (angular correction of the engagement) and operating (linear wear of the teeth) factors. It is shown that the angular correction enables us to get the optimal shifting coefficients for which the service life is maximum as compared with the uncorrected engagement. It is also demonstrated that the actual period of operation and load-carrying capacity of the gear is higher if we take into account the changes in the initial profiles of the teeth as a result of their wear.
TL;DR: In this paper, the authors applied coarse recycled hardmetal particles in combination with Ni-based matrix to produce wear resistant metal matrix composite (MMC) thick coatings using plasma transferred arc hardfacing (PTA) technology.
Abstract: The aim of this work was to apply coarse recycled hardmetal particles in combination with Ni-based matrix to produce wear resistant metal matrix composite (MMC) thick coatings using plasma transferred arc hardfacing (PTA) technology. Assignment of hardmetal waste as initial material can significantly decrease the production costs and improve the mechanical properties of coatings and, consequently, increase their wear resistance. The microstructure of MMC fabricated from a recycled powder was examined by optical and SEM/EDS microscopes, whereas quantitative analyses were performed by image analysis method. Micro-mechanical properties, including hardness and elastic modulus of features, were measured by nanoindentation. Furthermore, behaviour of materials subjected to abrasive and impact conditions was studied. Results show the recycled powder provides hardfacings of high quality which can be successfully used in the fabrication of wear resistant MMC coatings by PTA-technology. DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1334
TL;DR: In this paper, the state of the metal near the roll surfaces of solid-rolled railway wheels after operation is investigated and it is shown that the greatest changes in structure (phase components, grain, subgrain, and dislocation structures, phase precipitates, etc.) over the width of the working surface of wheels take place in the zone of passage to the flange and propagate to a depth of up to 200 to 300μm (from the roll surface).
Abstract: We describe the results of investigations of the state of the metal near the roll surfaces of solid-rolled railway wheels after operation. It is shown that the greatest changes in structure (phase components, grain, subgrain, and dislocation structures, phase precipitates, etc.) over the width of the working surface of wheels take place in the zone of passage to the flange and propagate to a depth of up to 200 to 300 μm (from the roll surface). The analytical estimate of changes in the strength and crack-resistance properties of the metal in different zones of railway wheels, based on the results of structural examinations, enabled us to establish that separate zones are characterized by a substantial strengthening of the near-surface layers, a dramatic increase in the local internal stresses up to the value of theoretical strength, and, correspondingly, a decrease in crack resistance.
TL;DR: In this article, the mechanical properties of 15Kh1M1F heat-resistant steel after long-term operation in steam pipelines of steam power plants were investigated and the anisotropy of its strength and plasticity characteristics as a result of degradation has been determined.
Abstract: We have investigated the mechanical properties of 15Kh1M1F heat-resistant steel after long-term operation in steam pipelines of steam power plants. The anisotropy of its strength and plasticity characteristics as a result of degradation has been determined. We have established that the number of shutdowns of the process in operation of the steel, orientation of specimens (axial, tangential, and radial), and their location in sections of pipe walls (near their external surface, internal surface, and at the center of the section) influence these parameters. The obtained results enable us to justify the choice of the orientation of specimens and their location in sections of pipes to provide the highest sensitivity of characteristics to a change in the technical state of the steel in operation.
TL;DR: In this paper, it was shown that after washing and drying cycle, the water vapour permeability of fabrics knitted from bamboo and synthetic yarns blend decreased predominantly and became similar to fabrics Knitted from cotton and respective synthetic yarn blend.
Abstract: Water vapour permeability and transport depends on the properties of the fibre and knitted fabric structure. It was designed double-layered fabrics knitted in plain plating pattern whose inner side was made from synthetic fibres the PES, PA, PP, and Coolmax ® (tetra-channel fibres by DuPont) which do not absorb moisture and on the surface of the wear – natural cotton and bamboo fibres which have good absorption properties. In the present research it was established that the air permeability of all fabrics after washing and drying cycle decreased. It occurred because of the influence of shrinkage during washing and drying under the impact of moisture, heat, and mechanical action. After washing and drying cycle, the water vapour permeability of fabrics knitted from bamboo and synthetic yarns blend decreased predominantly and became similar to fabrics knitted from cotton and respective synthetic yarns blend. The water vapour permeability of fabrics knitted from cotton and synthetic yarns blend decreased significant less. Depending on the knitting structure, the most decrease of water vapour permeability was estimated to the plain plated fabrics. DOI: http://dx.doi.org/10.5755/j01.ms.18.3.2438
TL;DR: In this paper, the influence of the long-term operation of API X52 pipeline steel on the degradation of its mechanical properties was analyzed, and it was found that after 30 years of operation, the strength and plasticity of the pipeline steel decreased substantially and the fatigue toughness decreased particularly abruptly.
Abstract: We analyze the influence of the long-term operation of API X52 pipeline steel on the degradation of its mechanical properties. It is established that, after operation for 30 years, its strength and plasticity characteristics decrease substantially, and the fatigue toughness decreases particularly abruptly, which is connected with the development of the damageability. We use indentation methods for comparing the states of the operated and nonoperated material. It is shown that the indices of spread of the results of measurements (the coefficient of variance) of the mechanical properties (hardness, wear, etc.) are more sensitive to the damage of the material in the initial state and the damage after operation than their averaged values. Some correlations between the Vickers hardness, cyclic hardness, strength, and plasticity of the steel are established.
TL;DR: In this paper, the authors deduce the relationship between the stress concentration and stress intensity factors for sharp and rounded notches and show that both the radius of rounding of the notch tip and the shape of its neighborhood strongly affect the distribution of stresses on the boundary contour.
Abstract: The solution of the antiplane problem of the theory of elasticity for a plane with semiinfinite rounded V-shaped notch is obtained by the method of singular integral equations. On this basis, we deduce the relationships between the stress concentration and stress intensity factors for sharp and rounded notches. The obtained solution is compared with the well-known solution of a similar problem for a hyperbolic notch. It is shown that both the radius of rounding of the notch tip and the shape of its neighborhood strongly affect the distribution of stresses on the boundary contour.
TL;DR: Kariskai avalynei skirtai odai isdirbti pasaulyje taikomos naujausios technologijos, nes si oda turi būti ypac hidrofobiska, bet kartu islaikyti gerą laidumą garams ir gebėjimą reguliuoti drėgmės mainus, t. y.
Abstract: Kariskai avalynei skirtai odai isdirbti pasaulyje taikomos naujausios technologijos, nes si oda turi būti ypac hidrofobiska, bet kartu islaikyti gerą laidumą garams ir gebėjimą reguliuoti drėgmės mainus, t. y. islaikyti higienines savybes. Todėl odos isdirbėjai turi naudoti tokias papildomo siksninimo chemines medžiagas, kurios suteiktų odai reikiamą atsparumą vandeniui ir laidumą vandens garams. Siame darbe tiriama chrominto pusgaminio papildomo siksninimo ir įriebinimo technologijų įtaka isdirbtos kariskos odos atsparumui vandeniui ir laidumui vandens garams. Atlikta Lietuvos ir Kazachstano isdirbtų odų lyginamoji analizė, siekiant nustatyti technologinių parametrų ir cheminių medžiagų įtaką vandens sugerciai, laidumui vandens garams bei vandens garų absorbcijai. DOI: http://dx.doi.org/10.5755/j01.ms.18.2.1918
TL;DR: In this article, Kokybiskai et al. discuss the effect of parametrization on parametrized parametrai: klijavimo temperatūra, slėgis ir trukmė, Istirtos keturios suklijamo siūlės.
Abstract: Aprangos gamyboje naudojami ne tik siūliniai, bet ir lydytiniai bei klijuotiniai sujungimai. Tam naudojama termoplastinė plėvelė. Pastarieji būdai pagrįsti pagrindinių ar klijuoti naudojamų medžiagų termoplastinių savybių panaudojimu. Kokybiskai sanklijai gauti parenkami tam tikri klijavimo parametrai: klijavimo temperatūra, slėgis ir trukmė. Suklijavimo stiprumas nustatomas atsluoksniuojant suklijuotus bandinius. Sio darbo tikslas – parinkti siūlės tipą, kuris tiktų įvairaus elastingumo medžiagų sanklijų stiprumui tirti. Tyrimo objektais pasirinktos penkios aprangos medžiagos: trys megztinės (poliesteris ir dvi medvilninės), audinys (poliesteris) ir laminatas (poliesteris). Medžiagoms tarpusavyje sujungti parinkta 0,09 μm storio termoplastinė poliuretaninė plėvelė. Istirtos keturios suklijamo siūlės. Tyrimo rezultatai parodė, kad suklijavimo stiprumui tirti tinkamiausia yra trecioji siūlė, kuri daugiausiai sumažina medžiagos elastingumą. DOI: http://dx.doi.org/10.5755/j01.ms.18.2.1922
TL;DR: In this article, the authors evaluated the influence of floating floor construction specimen size on weighted reduction in impact sound pressure level Δ L W, and found that the small size specimens had a strong influence.
Abstract: The aim of the research was to evaluate an influence of floating floor construction specimen size on weighted reduction in impact sound pressure level Δ L W . The large size (area ≥ 10 m 2 ) specimens should be used according to LST EN ISO 10140 series standards. The problem is that produce large specimens is expensive and time-consuming process. So more rapid and cheaper way is to use smaller size (area < 10 m 2 ) specimens and perform measurements in real buildings with similar test conditions as in laboratory. For evaluation of the specimen size influence on reduction in impact sound pressure level Δ L W value sand/cement screed area discreetly was reduced from 13.4 m 2 down to 0.5 m 2 . The test results showed strong dependence of reduction in weighted impact sound pressure level from specimen size. Relying on the test data it was derived relationship which could be applied for the correction of the determined Δ L W values when smaller size specimens (area < 10 m 2 ) of floating floor constructions are used. DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1350
TL;DR: In this paper, the authors estimate the characteristics of strength, ductility, and static crack resistance of 12Kh1MF steel taken from the stretched, compressed, and neutral zones of a vertical bend and a straight part of the main steam pipeline of a thermal power plant after ~ 1.3 ⋅105 h of operation.
Abstract: We estimate the characteristics of strength, ductility, and static crack resistance of 12Kh1MF steel taken from the stretched, compressed, and neutral zones of a vertical bend and a straight part of the main steam pipeline of a thermal power plant after ~ 1.3 ⋅105 h of operation. The anisotropy of the mechanical char acteristics in the diametric and axial sections of the pipe and their gradients across the thickness of the pipe wall in fracture are discovered.
TL;DR: In this paper, a physicochemical model and mathematical relations for the description of the stress-corrosion fracture of pipe materials of underground oil and gas pipelines with regard for the intensification of this process by diffusion-moving hydrogen were established.
Abstract: On the basis of the well-known theoretical concepts and some experimentally substantiated hypotheses, we propose a physicochemical model and establish mathematical relations for the description of the stress-corrosion fracture of pipe materials of underground oil-and-gas pipelines with regard for the intensification of this process by diffusion-moving hydrogen. We also quantitatively estimate the effect of hydrogenation on the rate of soil corrosion and residual service life of the pipes of oil-and-gas pipelines.
TL;DR: In this paper, a comparative analysis of the wear resistances of normalized steel 45 with surface nanostructure and ShKh15 steel after hardening and low-temperature tempering in an oil-abrasive medium is performed.
Abstract: A comparative investigation of the wear resistances of normalized steel 45 with surface nanostructure and ShKh15 steel after hardening and low-temperature tempering in an oil–abrasive medium is performed. It is shown that steel 45 has a higher wear resistance than ShKh15 steel. This enables one to replace an alloyed steel by a carbon steel with surface nanocrystalline structure in a friction unit and simultaneously improve the wear resistance of the carbon steel.
TL;DR: In this article, the authors present a survey of the state-of-the-art research work in the field of bioinformatics in the context of biomedical data analysis.
Abstract: Specialios paskirties lauko drabužiai turi atitikti aukstus patvarumo, siluminės istaigos ir drėgmės pernasos reikalavimus. Siems tikslams dažnai naudojamos membraninės termiskai aktyvios tekstilės medžiagos. Siekiant pagerinti sių tekstilės medžiagų isvaizda, gali būti naudojami įvairūs poveikiai, užtikrinantys superhidrofobinį savaime besivalantį pavirsių (žinomą kaip lotoso efektas). Įgyvendinant sią idėją, buvo atlikti žėrinciojo islydžio radijo dažnio inertinių dujų bei angliavandenilių dujų plazmos poveikio pramoninėms medžiagoms tyrimai. Gauti geri rezultatai tiriant savaiminio valymosi savybes empiriskai, tam naudojant dulkes ir kietąsias daleles. Skirtingos poveikio sąlygos buvo lyginamos matuojant kontaktinį vandens drėkinimo kampą. Daugeliu atvejų paveiktų medžiagų kontaktinis kampas buvo gerokai didesnis nei pradinių medžiagų. Didžiausia kampo vertė siekė 155°. Pavirsiaus istirtas naudojant skenuojamąjį elektroninį mikroskopą (SEM) bei SEM-EDX spektroskopiją. Silikoorganinių dujų plazma apdoroto pluosto pavirsiuje aptiktas plonas būdingos sferinės struktūros sluoksnis. DOI: http://dx.doi.org/10.5755/j01.ms.18.2.1920
TL;DR: In this article, the NiFe 2 O 4 and CoFe 2O 4 ferrites were synthesized by two methods, chemical sol-gel self-combustion method and the high frequency plasma chemical synthesis and magnetic properties, crystallite size, specific surface area of synthesized products are characterized.
Abstract: The NiFe 2 O 4 and CoFe 2 O 4 ferrites were synthesized by two methods – chemical sol-gel self-combustion method and the high frequency plasma chemical synthesis and magnetic properties, crystallite size, specific surface area of synthesized products are characterized. Nanopowders synthesized in the high frequency plasma are with specific surface area in the range of (28 – 30) m 2 /g (the average particle size (38 – 40) nm, crystallite size ~40 nm). The ferrite nanopowders obtained by sol-gel self-combustion method have the specific surface area of (37 – 43) m 2 /g (average particle size (26 – 31) nm, crystallite size (10 – 20) nm). All synthesized nanopowders were sintered via pressure-less sintering method and magnetic properties of compacted materials were studied, as well. DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1332