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Wyniki wyszukiwania dla: al2o3
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Measurement of temperature-dependent viscosity and thermal conductivity of alumina and titania thermal oil nanofluids
PublikacjaThe results of simultaneous measurements of dynamic viscosity, thermal conductivity, electrical conductivity and pH of two nanofluids, i.e. thermal oil/Al2O3 and thermal oil/TiO2 are presented. Thermal oil was selected as a base liquid because of possible application in ORC systems as an intermediate heating agent. Nanoparticles were tested at the concentration of 0.1%, 1% and 5% by weight within temperature range from 20°C to...
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Nonlinear impedance in oxide glasses containing single and mixed alkali ions
PublikacjaThe aim of the present was to find more clues on the nonlinearities in impedance of oxide glasses. The first family of researched glasses has a composition of FeO-P2O5-Na2O. Oxide glasses containing iron and alkali are well known for a very low alkali ion mobility and may be considered purely polaron conducting. These glasses show no detectable nonlinearities in the impedance spectra. The second was a family of ionic conducting...
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Vertical vibration reduction and audible sound analysis in surface grinding with electroplated tools
PublikacjaOne of the first approaches to the development of a grinding process monitoring system based on audible sound sensors is presented in the paper. Electroplated diamond tools (abrasive D64 and D107) were used in a modified single-disc lapping machine configuration for flat grinding of ceramics (Al2O3). The main aim of the machine modification was to reduce the vertical vibration in order to decrease the tool wear and to increase...
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MEASUREMENT OF TEMPERATURE-DEPENDENT VISCOSITY AND THERMAL CONDUCTIVITY OF ALUMINA AND TITANIA THERMAL OIL NANOFLUIDS
PublikacjaIn this study results of simultaneous measurements of dynamic viscosity, thermal conductivity, electrical conductivity and pH of two nanofluids, i.e. thermal oil/Al2O3 and thermal oil/TiO2 are presented. Thermal oil is selected as a base liquid because of possible application in ORC systems as an intermediate heating agent. Nanoparticles were tested at the concentration of 0.1%, 1% and 5% by weight within temperature range from...
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Stability Investigation of the PCM Nanocomposites
PublikacjaEnsuring the stability is a key issue to be solved for the technical application of nanocomposites. In this work, fatty acid P1801 served as base phase change material (PCM)P1801, and its main ingredients are palmitic acid (58%) and stearic acid (38%). Titania (TiO2) and alumina (Al2O3) with mass concentrations of 1% and 5% were selected as nanoparticles, while polyvinylpyrrolidone (PVP) or oleic acid (OA) with mass concentrations...
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Effect of Nb and Al on in vitro dissolution behavior and structure of Na2O-MgO CaO-P2O5 glasses
PublikacjaIn vitro dissolution, structure, and thermal properties of the glass series Na2O-MgOsingle bondCaOsingle bondNb2O5 -Al2O3-P2O5 were studied. The dissolution behavior in phosphate-buffered saline (PBS) confirmed the potential bioactive properties of tested glasses. The dissolution process was found to depend on the Al, Nb, and Mg contents. Al, respectively, suppresses the Nb and accelerates the Mg release process from the glasses....
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High temperature corrosion of evaporator tubes with thermal sprayed coatings
PublikacjaDegradation examinations of outer surface of low-emission steam boiler evaporator tubes are presented in the paper. Metallographic evaluation of scale morphology, its micro sites chemical composition analysis and distribution of elements on cross sections have been performed. Water-wall tubes were exposed in steam boiler for up to two years period. Common tubes made of 16Mo3 steel suffered sulphide and molten salts corrosions....
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Experimental Investigation of Free Convection Heat Transfer from Horizontal Cylinder to Nanofluids
PublikacjaThe results of free convection heat transfer investigation from a horizontal, uniformly heated tube immersed in a nanofluid are presented. Experiments were performed with five base fluids, i.e., ethylene glycol (EG), distilled water (W) and the mixtures of EG and water with the ratios of 60/40, 50/50, 40/60 by volume, so the Rayleigh (Ra) number range was 3 104 Ra 1.3 106 and the Prandtl (Pr) number varied from 4.4 to 176....
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Burnout Investigation of Small Diameter Tubes Immersed in Nanofluids
PublikacjaThis paper deals with research into pool boiling critical heat flux (CHF) of water–Al2O3, water–TiO2 and water–Cu nanofluids on horizontal stainless steel tubes. The experiments were conducted under atmospheric pressure. Nanoparticles were tested at concentrations of 0.001%, 0.01%, 0.1% and 1% by weight. Ultrasonic vibration was used in order to stabilize the dispersion of the nanoparticles. Although dispersants were not used to...
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Odporność wybranych powłok ochronnych na korozję płomieniową w kotłach pyłowych niskoemisyjnych
PublikacjaW artykule omówiono zagadnienie odporności powłok na rurach ekranowych kotłów niskoemisyjnych na korozję płomieniową. Przedstawiono wyniki badań diagnostycznych powłok ochronnych na rurach ekranowych kotłów pyłowych, niskoemisyjnych, pracujących przy współspalaniu biomasy. Badano powłoki natryskiwane cieplnie Al2O3/Ni- 30Cr oraz hybrydowe nanoszone techniką malarską. Stan powłok oceniono po jednym i dwóch latach eksploatacji w...
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Method of Monitoring of the Grinding Process with Lapping Kinematics Using Audible Sound Analysis
PublikacjaUtilising microphones as audible sound sensors for monitoring a single-side grinding process with lapping kinematics is presented in the paper. The audible sound generated during grinding depended on the cutting properties of electroplated tools with D107 diamond grains and different thicknesses of the nickel bond. The tool wear affected the obtained technological effects such as material removal rate and the surface roughness...
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Effect of Temperature and Nanoparticle Concentration on Free Convective Heat Transfer of Nanofluids
PublikacjaA theoretical analysis of the influence of temperature and nanoparticle concentration on free convection heat transfer from a horizontal tube immersed in an unbounded nanofluid was presented. The Nusselt (Nu) number and heat transfer coefficient were parameters of the intensity of the convective heat transfer. For free convection, the Nu number was a function of the Rayleigh (Ra) number and Prandtl (Pr) number. The Rayleigh (Ra)...
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Superconductivity in PrBa 2Cu 3O 7− δ single crystals after high-temperature thermal treatment
PublikacjaThe influence of post-growth treatment, consisting of high-temperature reduction, quench and oxidation, on the structural, electrical and magnetic properties of PrBa2Cu3O7−δ single crystals, obtained in Al2O3 and ZrO2 crucibles by the self-flux method, was examined. We report on the observation of inhomogeneous superconductivity in several Al-doped crystals from the ac magnetic susceptibility and resistivity measurements. Superconducting...
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Carburization Behavior of High-Grade Pellets After Direct Reduction in Pure Hydrogen
PublikacjaCarburization is a critical aspect in the iron and steel industry as it significantly affects the mechanical and chemical properties of the final product. This study provides a comprehensive analysis of the carburization potential of high-grade quality iron ore pellets after direct reduction in pure hydrogen. The results show that the porosity of the pellets has a significant impact on the efficiency and success of the direct reduction...
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Thermal analysis of Magnetohydrodynamics (MHD) Casson fluid with suspended Iron (II, III) oxide-aluminum oxide-titanium dioxide ternary-hybrid nanostructures
PublikacjaThis study is carried out to enhance and analyze the thermal performance of non-Newtonian Casson fluid by immersing Ternary hybrid nanoparticles Fe3O4-Al2O3-TiO2 uniformly. To model the behaviour of such complex phenomena mathematically, a system of complex transport differential equations is developed by utilizing a non-Fourier heat transfer model for energy transport. The non-dimensional system of transport equations involving...
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Nanolayers in Fiber-Optic Biosensing
PublikacjaIn this chapter, fiber-optic sensors based on nanolayers or thin films and their ability to perform biophotonic measurements is presented. In the last decade, fiber-optic sensors have gained popularity as biosensing devices. This has been made possible because of the design and the integration of new materials in fiber-optic technology. Nanolayers and thin films made from various materials such as nanodiamond (NCD), boron-doped...
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EFFECT OF NANOFLUID CONCENTRATION ON TWO-PHASE THERMOSYPHON HEAT EXCHANGER PERFORMANCE
PublikacjaAn approach – relaying on application of nanofluid as a working fluid, to improve performance of the two-phase thermosyphon heat exchanger (TPTHEx) has been proposed. The prototype heat exchanger consists of two horizontal cylindrical vessels connected by two risers and a downcomer. Tube bundles placed in the lower and upper cylinders work as an evaporator and a condenser, respectively. Distilled water and nanofluid water-Al2O3...
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Uwodornienie oleju sojowego i rzepakowego na katalizatorach miedziowych promotorowanych niklem i tlenkiem glinu. Hydrogenation of soybean and rapeseed oil with copper catalysts activated with nickel and aluminium oxide
PublikacjaBadano nowy typ katalizatorów miedziowych promotorowanych niklem, o stosunku Cu do Ni w granicach od 1:0,0036 do 1:0,018 w?w, osadzonych na Al2O3, przeznaczonych do selektywnego uwodornienia kwasu linolenowego w olejach roślinnych. Uwodornienie prowadzono w laboratoryjnym reaktorze typu "dead end" na oleju sojowym i rzepakowym, a kontakty mieszane - w stęż. 0,5% i 1% Cu. Na podstawie badań stwierdzono, że promotorowanie znacząco...
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Combined Long-Period Fiber Grating and Microcavity In-Line Mach–Zehnder Interferometer for Refractive Index Measurements with Limited Cross-Sensitivity
PublikacjaThis work discusses sensing properties of a long-period grating (LPG) and microcavity in-line Mach–Zehnder interferometer (µIMZI) when both are induced in the same single-mode optical fiber. LPGs were either etched or nanocoated with aluminum oxide (Al2O3) to increase its refractive index (RI) sensitivity up to ≈2000 and 9000 nm/RIU, respectively. The µIMZI was machined using a femtosecond laser as a cylindrical cavity (d = 60...
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Ion conduction in beryllium-alumino-silicate glasses doped with sodium or sodium and lithium ions
PublikacjaElectrical properties of beryllium-alumino-silicate glasses containing sodium ions or sodium and lithium ions were studied with impedance spectroscopy technique over a frequency range from 10 mHz to 1 MHz and at temperature range from 213 to 473 K. The frequency- and temperature-dependent conductivity spectra of individual single alkali glasses were superimposed by means of the Summerfield scaling. Mixed-alkali glasses do not overlap...
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Evolution of magnetic and transport properties in (Cr1−xMnx)2AlC MAX-phase synthesized by arc melting technique
PublikacjaHerein we initiate a comeback to the arc melting technique to produce MAX-phase solid solutions. Bulk samples of (Cr1−xMnx)2AlC MAX-phase with X = 0, 0.025, 0.05 and 0.1 were synthesized and studied by means of X-ray diffractometry, scanning electron microscopy in combination with energy-dispersive X-ray spectroscopy. Samples were established to be homogeneous with an incorporation of Cr7C3, AlCr2 and Al2O3 secondary phases which...
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Impact of Temperature and Nanoparticle Concentration on Turbulent Forced Convective Heat Transfer of Nanofluids
PublikacjaTheoretical analysis of the influence of nanoparticles and temperature on the average Nusselt (Nu) number and the average heat transfer coefficient (HTC) during the turbulent flow of nanofluid in a horizontal, round tube was carried out. The Nu number is a function of the Reynolds (Re) number and the Prandtl (Pr) number, which in turn are functions of the thermophysical properties of the liquid and the flow conditions. On the other...
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Effect of composition on the thermal properties and structure of M-Al-Si-O-N glasses, M = Na, Mg, Ca
PublikacjaThe primary objective of this study is to explore the relationship between the composition, structure, and thermal characteristics of M-Al-Si-O-N glasses, with M representing sodium (Na), magnesium (Mg), or calcium (Ca). The glasses were prepared by melting in a quartz crucible at 1650 °C and AlN precursor (powder) was utilized as a nitrogen source. The measured thermal properties studied were glass transition temperature (Tg),...
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Badania nad docieraniem płaskich elementów ceramicznych z wymuszonym dawkowaniem zawiesiny ściernej
PublikacjaW pracy przedstawiono zagadnienia dotyczące obróbki wykończeniowej płaskich uszczelnień ceramicznych. Wymagania obróbkowe stawiane tego typu elementom sprawiają, że konieczne jest zastosowanie docierania w procesie technologicznym. Tego typu bardzo dokładna obróbka ścierna powierzchni płaskich wymaga użycia odpowiedniej zawiesiny lub pasty ściernej. Na wynik obróbki ma wpływ wiele czynników związanych z metalową tarczą docierającą,...
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Pool boiling of nanofluids on rough and porous coated tubes: experimental and correlation
PublikacjaThe paper deals with pool boiling of water-Al2O3 and water- Cu nanofluids on rough and porous coated horizontal tubes. Commercially available stainless steel tubes having 10 mm outside diameter and 0.6 mm wall thickness were used to fabricate the test heater. The tube surface was roughed with emery paper 360 or polished with abrasive compound. Aluminium porous coatings of 0.15 mm thick with porosity of about 40% were produced by...
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A new hyperbolic-polynomial higher-order elasticity theory for mechanics of thick FGM beams with imperfection in the material composition
PublikacjaA drawback to the material composition of thick functionally graded materials (FGM) beams is checked out in this research in conjunction with a novel hyperbolic‐polynomial higher‐order elasticity beam theory (HPET). The proposed beam model consists of a novel shape function for the distribution of shear stress deformation in the transverse coordinate. The beam theory also incorporates the stretching effect to present an indirect...
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Low-Coherence Interferometric Fiber-Optic Sensors with Potential Applications as Biosensors
PublikacjaFiber-optic Fabry-Pérot interferometers (FPI) can be applied as optical sensors, and excellent measurement sensitivity can be obtained by fine-tuning the interferometer design. In this work, we evaluate the ability of selected dielectric thin films to optimize the reflectivity of the Fabry-Pérot cavity. The spectral reflectance and transmittance of dielectric films made of titanium dioxide (TiO2) and aluminum oxide (Al2O3) with...
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Low-Coherence Interferometric Fiber-Optic Sensors with Potential Applications as Biosensors
PublikacjaFiber-optic Fabry-Pérot interferometers (FPI) can be applied as optical sensors, and excellent measurement sensitivity can be obtained by fine-tuning the interferometer design. In this work, we evaluate the ability of selected dielectric thin films to optimize the reflectivity of the Fabry-Pérot cavity. The spectral reflectance and transmittance of dielectric films made of titanium dioxide (TiO2) and aluminum oxide (Al2O3) with...
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Treatment Wetland effluent quality improvement by usage sorbents of various origin
PublikacjaTWs are finding as low-cost and also effective system to treat domestic wastewater. The aim of this study is to find suitable adsorbing material for application in an additional treatment unit where treatment wetlands do not provide sufficient PO4 3- reduction level. Material M1 is a fine-grained by-product of thermal treatment of carbonate-siliceous rock (opoka) with high content of calcium carbonate CaCO3 in temperature 700°C....
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Możliwość wykorzystania popiołów z osadów ściekowych w betonie
PublikacjaIlość popiołów lotnych ze spalania osadów ściekowych rośnie na całym świecie. Ich unieszkodliwianie jest poważnym problemem ekologicznym. W pracy przedstawiono ocenę możliwości wykorzystania popiołów lotnych z osadów ściekowych w betonie. Wykonano dwie serie badawcze dla dwóch współczynników (w/s) równych 0,49 oraz 0,55 z udziałem 10% i 20% popiołu lotnego (SSA), jako zamiennika cementu. Skład chemiczny wykazał, że popiół (SSA)...
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Influence of Cement Replacement with Sewage Sludge Ash (SSA) on the Heat of Hydration of Cement Mortar
PublikacjaThe amount of fly ash from the incineration of sewage sludge is increasing all over the world, and its utilization is becoming a serious environmental problem. In the study, a type of sewage sludge ash (SSA) collected directly from the municipal sewage treatment plant was used. Five levels of cement replacement (2.5%, 5%, 7.5%, 10% and 20%) and unchanged water-to-binder (w/b) ratio (0.55) were used. The purpose of the study was...
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Wpływ parametrów dawkowania wymuszonego zawiesiny ściernej na efekty docierania jednotarczowego powierzchni płaskich elementów ceramicznych
PublikacjaPrzedmiotem rozprawy doktorskiej jest analiza wpływu parametrów dawkowania wymuszonego zawiesiny ściernej na efekty docierania jednotarczowego powierzchni płaskich elementów ceramicznych. W pierwszej części pracy opisano proces docierania elementów na docierarkach jednotarczowych. Opisano rolę ziaren ściernych i mechanizm procesu docierania elementów ceramicznych AL2O3 na docierarkach jednotarczowych. Dokonano również przeglądu...
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Optimization of Hydrogen Utilization and Process Efficiency in the Direct Reduction of Iron Oxide Pellets: A Comprehensive Analysis of Processing Parameters and Pellet Composition
PublikacjaThe article deals with the H2 consumption for different processing conditions and the composition of the processed pellets during the direct reduction process. The experiments are carried out at 600–1300 °C, with gas pressures of 1–5 bar, gas flow rates of 1–5 L min−1, and basicity indices of 0 to 2.15. Pellets with different compositions of TiO2, Al2O3, CaO, and SiO2 are analyzed. The gas flow rate is crucial, with 0–10 L min−1...
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Microgrinding with single-disk lapping kinematics.
PublikacjaGrinding operations are carried out with a variety of tool-workpiece configurations. The selection of a grinding process for a particular application depends on part shape, part size, ease of fixture, requirements concerning the acceptable shape errors. It is evident that lapping is very effective in eliminating the waviness while surface grinding is not. Dual disk machines for the double face grinding with planetary kinematics...
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Three-dimensional numerical investigation of hybrid nanofluids in chain microchannel under electrohydrodynamic actuator
PublikacjaEnergy efficiency enhancement methods have received considerable attentionwithin the industry and scientific community, owing to the rising concern ofglobal energy sustainability. The present article attempts to scrutinize the effectsof electrohydrodynamics and nanofluids on the rate of heat transfer and fluidflow in the 3-D chain microchannels. Improved heat exchangers (e.g., chainmicrochannel) would have a key role in increasing...
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Research on Tool Temperature Dependence on Lapping Grains Size
PublikacjaCommonly used as a finishing operation, lapping has been used for achieving ultra-high finishes and close tolerances between mating pieces. Its carried out by applying loose abrasive grains between work and lap surfaces, and causing a relative motion between them resulting in a finish of multi-directional lay. The grains activity (sliding and rolling) in the working gap causes not only the material removal but also the temperature...
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Effects of La0.8Sr0.2MnO3 and Ag electrodes on bismuth-oxide-based low-temperature solid electrolyte oxygen generators
PublikacjaIn this study, La0.8Sr0.2MnO3 (LSM) was used as the ceramic electrode in a (Bi1.50Y0.50)0.98Zr0.04O3+δ (BYO)-based solid electrolyte oxygen generator (SEOG) and its performance was compared with that of a previously studied high-fire Ag electrode. Among La0.6Sr0.4Co0.2Fe0.8O3, LaNi0.6Fe0.4O3, Cu1.4Mn1.6O4, and LSM materials, only LSM materials did not trigger any chemical reaction or interdiffusion with BYO at temperatures up to...
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Influence of the particle size of carbonate-siliceous rock on the efficiency of phosphorous removal from domestic wastewater
PublikacjatThe aim of the study was to determine the influence of the particle size of carbonate–silica rock (opoka)used in rock filters on the efficiency of phosphorus removal from domestic wastewater. The investigationswere carried out in a laboratory using a model consisting of three vertical flow filters with carbonate–silicarock of different particle sizes (G1= 1–2 mm; G2= 2–5 mm; G3= 5–10 mm). The tested rock was subjectedto decarbonising...