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Wyniki wyszukiwania dla: POLYETHYLENE, INORGANIC FILLER, COMPOSITE, MECHANICAL PROPERTIES, DYNAMIC MECHANICAL ANALYSIS
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On the necessity of experimental verification of numerical results in biomedical applications
PublikacjaPorous structures made of metal or biopolymers with a structure similar in shape and mechanical properties to human bone can be easily produced by stereolitography techniques, e.g. selective laser melting (SLM). Numerical techniques, like finite element method (FEM) have great potential in testing new, even the most sophisticated designs, according to their mechanical properties, i.e. strength or stiffness. However, due to different...
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Structural and Material Determinants Influencing the Behavior of Porous Ti and Its Alloys Made by Additive Manufacturing Techniques for Biomedical Applications
PublikacjaOne of the biggest challenges in tissue engineering is the manufacturing of porous structures that are customized in size and shape and that mimic natural bone structure. Additive manufacturing is known as a sufficient method to produce 3D porous structures used as bone substitutes in large segmental bone defects. The literature indicates that the mechanical and biological properties of scaffolds highly depend on geometrical features...
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Dynamic modeling of non-cylindrical curved viscoelastic single-walled carbon nanotubes based on the second gradient theory
PublikacjaThis paper is devoted to the theoretical study of the dynamic response of non-cylindrical curved viscoelastic single-walled carbon nanotubes (SWCNTs). The curved nanotubes are largely used in many engineering applications, but it is challenging in understanding mechanically the dynamic response of these curved SWCNTs when considering the influences of the material viscosity. The viscoelastic damping effect on the dynamic response...
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Novel method of estimation of inertial and dissipative parameters of a railway pantograph model
PublikacjaAn increase in electric railway vehicles service velocity requires that correct interaction between the pantograph and the catenary is ensured. This implies the need for developing mathematical models of pantographs and catenaries and determining their parameters. The article presents a method to determine parameters of mechanical joints of a railway pantograph based on analysis of pantograph subassemblies in swinging motion. The...
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Analiza przepływu oleju przez rowek smarowy wzdłużnego łożyska ślizgowego z wykorzystaniem komputerowej dynamiki płynów (CFD) = Analysis of the lubricant flow through the hydrodynamic thrust bearings groove with the use of computational fluid dynamic
PublikacjaSmarowanie zanurzeniowe jest tradycyjnym sposobem smarowania wzdłużnych łożysk ślizgowych. Jednak rozwiązanie to wykazuje umiarkowaną skuteczność w zapewnieniu optymalnie niskich temperatur w filmie smarowym a ponadto jest przyczyną strat mocy związanych z mieszaniem oleju w obudowie łożyska, co jest szczególnie widoczne w łożyskach szybkoobrotowych. Obecnie wymagania stawiane nowym konstrukcjom łożysk ślizgowych to zwiększanie...
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Novel bio-based thermoplastic poly(ether-urethane)s. Correlations between the structure, processing and properties
PublikacjaThe main purpose of this work was to analyze the effect of the number of unreacted isocyanate groups and the [NCO]/[OH] molar ratio during the chain extension of a prepolymer during the polymerization process on the structure, processing and selected properties of thermoplastic poly(ether-urethane)s. Three series of novel thermoplastic polyurethanes were obtained via a prepolymer route. Three prepolymers were synthesized from diisocyanate...
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Investigating the combined impact of plasticizer and shear force on the efficiency of low temperature reclaiming of ground tire rubber (GTR)
PublikacjaIn the present work, ground tire rubber (GTR) was mechano-chemically reclaimed at ambient temperature using two-roll mills. Road bitumen and styrene-butadiene-styrene (SBS)-modified bitumen at variable content (in range: 2.5–20 phr) were applied as reactive plasticizers to enhance reclaiming of GTR. For better understanding the plasticizing effect of bitumen on the quality of obtained reclaimed rubber, mechano-chemically reclaimed...
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Tensile modulus of human orbital wall bones cut in sagittal and coronal planes
PublikacjaIn the current research, 68 specimens of orbital superior and/or medial walls taken from 33 human cadavers (12 females, 21 males) were subjected to uniaxial tension untill fracture. The samples were cut in the coronal (38 specimens) and sagittal (30 specimens) planes of the orbital wall. Apparent density (ρapp), tensile Young’s modulus (E-modulus) and ultimate tensile strength (UTS) were identified. Innovative test protocols were...
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Three-Dimensional Printing of Bone Models
PublikacjaThe trabecular bone occurs, for example, in the femoral heads. Understanding the phenomenon of bone tissue degeneration can be the basis for the possibility of looking for alternative methods of surgical treatment of bone loss. The paper presents the results of the trabecular bone model, which was produced in additive manufacturing method with fused filament fabrication technology. The verification of the mechanical behavior of...
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Surface modifications of ti and its alloys
PublikacjaThis article reviews the various surface modification techniques pertaining to titanium and titanium alloys including physical treatment, mechanical treatment, and chemical and electrochemical treatment. The proper surface modification expands the use of titanium and its alloys in the biomedical field for long-term implants retaining the excellent properties of substrate material and improving the specific surface properties required...
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Thermodynamics of solid phases containing rare earth oxides
PublikacjaRare earth elements (RE) are incorporated into a large variety of complex oxide phases to provide tailored mechanical, electrical, optical, and magnetic properties. Thermodynamics control phase stability, materials compatibility in use, corrosion, and transformation. This review presents, in one compilation, the thermodynamic properties of a large number of such materials and discusses systematic trends in energetics and the factors...
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Liquefaction of alder wood as the source of renewable and sustainable polyols for preparation of polyurethane resins
PublikacjaLiquefaction of wood-based biomass gives different polyol properties depending on the reagents used. In this article, alder wood sawdust was liquefied with glycerol and poly(ethylene glycol) solvents. Liquefaction reactions were carried out at temperatures of 120, 150 and 170 °C. The obtained bio-polyols were analyzed in order to establish the process efficiency, hydroxyl number, acid value, viscosity and structural characteristics...
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Application of Pierson-Moskowitz wave spectrum to solution differential equations of multihull vessel
PublikacjaMotion of a dynamic system can be generated by different external or internal factors. At mathematical modelling external excitation factors of the most significant effect on the system, are selected. Such external factors are usually called excitations. Response of the system to given excitations is mathematically characterized by a definite transformation called operator of a system. For a broad class of dynamic systems the...
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The influence of crude glycerol and castor oil-based polyol on the structure and performance of rigid polyurethane-polyisocyanurate foams
PublikacjaIn this work, biopolyol obtained from two types of industrial crops’ processing products: crude glycerol and castor oil was used for preparation or rigid polyurethane-polyisocyanurate foams. Bio-based polyol was obtained via crude glycerol polymerization and further condensation of resulting polyglycerol with castor oil. Rigid polyurethane-polyisocyanurate foams were prepared at partial substitution (0–70 wt.%) of petrochemical...
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Obtaining and Characterization of the PLA/Chitosan Foams with Antimicrobial Properties Achieved by the Emulsification Combined with the Dissolution of Chitosan by CO2 Saturation
PublikacjaA new method of obtaining functional foam material has been proposed. The materials were created by mixing the poly lactic acid (PLA) solution in chloroform, chitosan (CS) dissolved in water saturated with CO2 and polyethylene glycol (PEG), and freeze-dried for removal of the solvents. The composite foams were characterized for their structural (SEM, FT-IR, density, porosity), thermal (DSC), functional (hardness, elasticity, swelling...
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Obtaining and Characterization of the PLA/Chitosan Foams with Antimicrobial Properties Achieved by the Emulsification Combined with the Dissolution of Chitosan by CO2 Saturation
PublikacjaA new method of obtaining functional foam material has been proposed. The materials were created by mixing the poly lactic acid (PLA) solution in chloroform, chitosan (CS) dissolved in water saturated with CO2 and polyethylene glycol (PEG), and freeze-dried for removal of the solvents. The composite foams were characterized for their structural (SEM, FT-IR, density, porosity), thermal (DSC), functional (hardness, elasticity, swelling...
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Non-Isocyanate-Based Waterborne Polyurethanes
PublikacjaNon-isocyanate polyurethanes (NIPUs) are a greener alternative for the conventional polyurethanes synthesized using toxic and moisture-sensitive di- or polyisocyanates. The most often described method of NIPU synthesis involves the reaction of five-membered cyclic carbonates with amines, and resulting polymers containing primary and secondary hydroxyl groups (so they are also known as polyhydroxyurethanes), which can be further...
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CFGFRPT Piles with a Circular Cross-Section and their Application in Offshore Structures
PublikacjaThe possibilities of using concrete piles in a polymer composite reinforced with glass fibres in offshore facilities were shown. Laboratory tests of CFGFRPT type piles compressed axially and in eccentric compression for the analysis of CFGFRPT piles were used. Methods of analysis of dynamic systems for mathematical modelling of the displacement of the hammer in the pile driving process were applied. The possibilities of combining...
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Polyurethane Nanocomposites Containing Reduced Graphene Oxide, FTIR, Raman, and XRD Studies
PublikacjaRecently, graphene and other graphene-based materials have become an essential part of composite science and technology. Their unique properties are not only restricted to graphene but also shared with derivative compounds like graphene oxide, reduced graphene oxide, functionalized graphene, and so forth. One of the most structurally important materials, graphene oxide (GO), is prepared by the oxidation of graphite. Though removal...
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Developing Materials for Biodegradable Otolaryngological Stents
PublikacjaMaterials for otolaryngological stents have to be characterized by good tensile strength, wear resistance, biocompatibility, and specific degradation time. This work aimed to synthesize polyurethanes based on various biodegradable polyol blends. Their biodegradability and mechanical properties were tested and compared to commercial BIOFLEX material.
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Polyurethane Glycerolysate as a Modifier of the Properties of Natural Rubber Mixtures and Vulcanizates
PublikacjaChemical recycling of polyurethanes can be realized in several different ways, but the most important methods are glycolysis and glycerolysis. Both methods permit recovery of polyols (when the process is realized with the mass excess of depolymerizing agent) or substitutes of polyols, which contain urethane moieties in the main chains and terminate mainly in hydroxyl groups (when the process is realized with the mass excess of...
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Novel Research on Biomedical Polyurethanes
PublikacjaThe variety of mechanical properties characterizes properly designed PURs. They may be biocompatible and reveal compatibility with blood, making them attractive materials for the fabrication of tissue scaffolds; however, like all synthetic materials, PURs don’t reveal sufficient biocompatibility. PURs may undergo certain chemical modifications (e.g., 1,4:3,6-dianhydro-D-sorbitol, ascorbic acid (AA), growth factors, covering with...
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Injectable bone cement based on magnesium potassium phosphate and cross-linked alginate hydrogel designed for minimally invasive orthopedic procedures
PublikacjaBone cement based on magnesium phosphate has extremely favorable properties for its application as a bioactive bone substitute. However, further improvement is still expected due to difficult injectability and high brittleness. This paper reported the preparation of novel biocomposite cement, classified as dual-setting, obtained through ceramic hydration reaction and polymer cross-linking. Cement was composed of magnesium potassium...
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Synthesis and characterization of biopolyols through biomass liquefaction of wood shavings and their application in the preparation of polyurethane wood composites
PublikacjaThe sustainability of production systems in wood processing, wood industry, and wooden waste disposal is an important issue for European industry and society. Proper development of products based on renewable wood resources gives an opportunity to provide materials with long-term environmental, social, and economic sustainability. This study aims to establish a new way of forestry and agricultural waste materials utilization by...
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Development of fragility curves in adjacent steel moment-resisting frames considering pounding effects through improved wavelet-based refined damage-sensitive feature
PublikacjaFragility curves present useful information related to earthquake-induced probability assessment of steel moment-resisting frames (MRFs) and determine the probability of the damage exceedance at different floor levels of MRFs. The review of the literature shows that most of the previous studies dealing with the fragility curves were based on conventional measures, such as spectral acceleration at the first mode period, peak...
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Electrochemical characterization of a composite comprising PEDOT/PSS and N doped TiO2 performed in aqueous and non-aqueous electrolytes
PublikacjaNitrogen doped titania (N-TiO2) was used as an inorganic component of composite electrodes containing poly(3,4-ethylenedioxythiophene) with poly(4-styrenesulphonate) PEDOT/PSS/N-TiO2. The composite materials were obtained by direct electrodeposition from an N-TiO2 suspension containing polyelectrolyte (NaPSS) and monomer EDOT. The electrodes were electrochemically tested in aqueous and non-aqueous electrolytes using cyclic voltammetry...
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Control of nonlinear and linearized model of self-balancing electric motorcycle
PublikacjaSelf-Balancing Electric Motorcycle (SBEM) is a dynamic and nonlinear electro-mechanical system. In this paper, the process of mathematical modelling and line-arization of SBEM is presented. The model of the control system in Matlab envi-ronment is implemented. The control system using the PID controller is designed. The operation of particular structures of the PID controller on the simulation model is compared. Due to simulation...
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PLA–Potato Thermoplastic Starch Filament as a Sustainable Alternative to the Conventional PLA Filament: Processing, Characterization, and FFF 3D Printing
PublikacjaThe growing popularity of the fused filament fabrication (FFF) 3D printing technology in science, industry, and in-home use is associated with an increased demand for high-quality polymer filaments. This study presents an in-depth characterization and analysis of a self-made bio-based polylactide (PLA)/thermoplastic potato starch (TPS) filament dedicated for the FFF 3D printing technology. The obtained results were compared with...
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Nanotubular oxide layers and hydroxyapatite coatings on ‘Ti–13Zr–13Nb’ alloy
PublikacjaThe presented research was aimed to determine the mechanical properties of the nanotubular oxide layer covered with hydroxyapatite coating. The Ti–13Zr–13Nb alloy was oxidised in 1M phosphoric acid with an addition of 0?5% HF for HF solution at 20 V voltage. The electrochemically assisted deposition of hydroxyapatite was performed at cyclic polarisation in NH4H2PO4 and CaCl2 solution at 80uC. The mechanical properties were determined...
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The Application of Fibres from Recycled Postconsumer Tyres for Concrete Reinforcement
PublikacjaPoland as a Member State is obliged to implement the EU specific environmental legislation focused on the reduction, transport and treatment of waste. The Landfill Directive prohibited the landfilling of whole tyres and their by-products. Although the EU Directive of Waste limits the use of tyres as secondary fuel, Poland is still the EU leader in burning tyres in cement kilns. Post-consumer tyres are utilised in a number of...
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Synthesis of isotactic polypropylene- block -polystyrene block copolymers as compatibilizers for isotactic polypropylene/polyphenylene oxide blends
PublikacjaPoly(2,6-dimethyl-1,4-phenylene oxide) (PPO) and isotactic polypropylene (iPP) are highly incompatible and consequently their uncompatibilized blends are quite brittle regardless of the molecular weights and ductility of the individual components. Isotactic polypropylene-polystyrene block copolymers, to be applied as compatibilizers for a broad range of PPO/iPP blend compositions, were prepared by mechanism transformation from...
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Experimental Study on the Effectiveness of Polyurethane Flexible Adhesive in Reduction of Structural Vibrations
PublikacjaThe aim of the present study is to consider the idea of using polyurethane flexible adhesive in to reduce the vibrations in structures exposed to dynamic loads and evaluate their damping properties in relation to large deformations. Firstly, two aluminium cantilever beams, simulating structural elements (without and with polyurethane layer in the form of tape), were analysed, in order to check the damping of the unconstrained polymer...
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Recycled Polyurethane as a Second Phase in Thermoset Blends and Its Effect on Thermal Degradation Kinetics Studies
PublikacjaA new approach is introduced in the modification of thermosetting polymer by using different amount of polyurethane of waste origin. The post consumer polyurethane foam coatings are degraded using glycolysis process and the recycled product is further converted into new polyurethane. The blending of recycled polyurethane with epoxy exhibits transparency and produces nanostructures. The effective interaction between two polymers...
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The investigation of polyester composites filled by modified bentonite
PublikacjaPraca dotyczy zagospodarowania odpadów poliestrowo-szklanych przez wytworzenie kompozytów z ich użyciem oraz żywicy poliestrowej, mączki dolomitowej i nanonapełniacza. Wykazano, ze dodatek 2% nanonapełniacza do do kompozytów poliestrowych zawierających 15% masowych odpadów pozwala na uzyskanie materiału wykazującego korzystne właściwości wytrzymałościowe. Proponowany sposób modyfikacji kompozytów poliestrowych jest nowym rozwiązaniem...
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The Green Approach to the Synthesis of Bio-Based Thermoplastic Polyurethane Elastomers with Partially Bio-Based Hard Blocks
PublikacjaBio-based polymeric materials and green routes for their preparation are current issues of many research works. In this work, we used the diisocyanate mixture based on partially bio-based diisocyanate origin and typical petrochemical diisocyanate for the preparation of novel bio-based thermoplastic polyurethane elastomers (bio-TPUs). We studied the influence of the diisocyanate mixture composition on the chemical structure, thermal,...
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Influence of the Square Wave Voltage on Dynamical Properties of a Flat Voltammetric Electrode in the Time Domain by the Electrochemical Reversible Reaction
PublikacjaIn this article there is a presentation of the analysis of the polarizing voltage shape influencing dynamic properties of voltammetric electrodes when on their surface reversible reaction takes place in the time domain. The electrode polarization with linearly increasing voltage and with a square component, was analyzed. The analysis that were conducted showed that the voltammetric electrode behaves like a first order transducer....
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Investigation into the Effect of Spinel Pigments on the Photostability and Combustion Properties of Ethylene-Norbornene Copolymer
PublikacjaMulticolor ethylene-norbornene (EN) composites filled with three different spinel pigments (Cobalt Green-PG50, Zinc Iron Yellow-PY 119, Praseodym Yellow-PY159) were prepared by melt mixing and characterized in terms of their stability under destructive environmental conditions. The EN films were subjected to accelerated aging by ultraviolet (UV) photooxidation for 300 h, 600 h, or 900 h. The mechanical performance of the EN composites...
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Materials Design for the Titanium Scaffold Based Implant
PublikacjaThe main objective of here presented research is a design the scaffold/porous titanium(Ti) alloy based composite material demonstrating better biocompatibility, longer lifetime andbioactivity behaviour for load-bearing implants. The development of such material is proposed bymaking a number of consecutive tasks. Modelling the mechanical, biomechanical and biologicalbehavior of porous titanium structure and an elaboration of results...
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Materials Design for the Titanium Scaffold Based Implant
PublikacjaThe main objective of here presented research is a design the scaffold/porous titanium(Ti) alloy based composite material demonstrating better biocompatibility, longer lifetime andbioactivity behaviour for load-bearing implants. The development of such material is proposed bymaking a number of consecutive tasks. Modelling the mechanical, biomechanical and biologicalbehavior of porous titanium structure and an elaboration of results...
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Starch-clay nanocomposite films
PublikacjaStarch is a natural polymer which, due to its renewability, biodegrability, availability and a relatively low cost, has a high potential for applications in biodegradable materials. However, because of its hydrophilic nature, the number of commercially available starch-based products is still limited. Recently, starch-based nanocomposites with the addition of clay minerals as nanofillers have given rise to large-scale improvements...
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A method to assess transverse vibration energy of ship propeller shaft for diagnostic purposes
PublikacjaThe article discusses a key problem of ship propulsion system vibration diagnostics, which concerns assessing this part of mechanical energy transmitted from the main engine to the ship propeller which is dissipated due to propeller shaft vibration. A simplified calculation model is proposed which allows the total energy of the generated torsional vibration to be assessed from the shaft deflection amplitude measured at the mind-span...
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Assessment of Subsoil Subsidence Under the Railway Surface with the Use of Fuzzy Sets
PublikacjaThe cause of the subsidence of the railway track is the subsidence of the track bed itself and it is often related to the subsidence of the subsoil. Such settlement leads to: uneven longitudinal railways and track twist. These phenomena have a negative impact on the comfort and safety of driving, and in extreme cases lead to a train derailment. It has been shown that the magnitude of these settlements is determined by many parameters...
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Preliminary Investigation on Auto-Thermal Extrusion of Ground Tire Rubber
PublikacjaGround tire rubber (GTR) was processed using an auto-thermal extrusion as a prerequisite to green reclaiming of waste rubbers. The reclaimed GTR underwent a series of tests: thermogravimetric analysis combined with Fourier-transform infrared spectroscopy (TGA-FTIR), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and static headspace and gas chromatography-mass spectrometry (SHS-GC-MS) in order...
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Evaluation of reformer tubes degradation after long term operation
PublikacjaPurpose of this paper is to show the effect of long-term service at elevated temperatures on microstructural changes of cast steel reformer tubes made of the alloy IN-519 (24%Cr, 24%Ni, Nb). The relationship between mechanical properties and microstructure degradation is discussed. Investigations were performed on five tubes taken from ammonia reformer furnace. Tubes worked at temperature of 880C and 3,2 MPa pressure. The operation...
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Influence of Two-Stage Anodization on Properties of the Oxide Coatings on the Ti–13Nb–13Zr Alloy
PublikacjaThe increasing demand for titanium and its alloys used for implants results in need of such innovative surface treatment that may jointly increase corrosion resistance and biocompatibility, and demonstrate antibacterial protection at no cytotoxicity. The purpose of this research was to characterize the effect of two-stage anodization, performed for 30 min in phosphoric acid, at the presence of hydrofluoric acid in the second stage....
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Evaluation of the Cathodic Electrodeposition Effectiveness of the Hydroxyapatite Layer Used in Surface Modification of Ti6Al4V-Based Biomaterials
PublikacjaThe important issue associated with the design and the fabrication of the titanium and titanium alloy implants is the increase of their biointegration with bone tissue. In the presented paper, the research results concerning the conditions used in the cathodic deposition of hydroxyapatite on the surface Ti6Al4V substrates primarily modified by the production of TiO2 nanoporous coatings, TiO2 nanofibers, and titanate coatings, are...
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Modulation of dielectric properties in low-loss polypropylene-based composites at GHz frequencies: theory and experiment
PublikacjaPolymer composites with high dielectric constant and low loss tangent are highly regarded as substrates for modern high-speed electronics. In this work, we analyze the high-frequency dielectric properties of two types of composites based on polypropylene infused with high-dielectric-constant microparticles. Two types of fillers are used: commercial ceramics or titanium oxide ( TiO2) with different concentrations. The key observation...
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Analysis of the cyclic load-unload-reload tests of VALMEX aged fabric
PublikacjaThe paper presents mechanical response of the VALMEX fabric during the cyclic loading-unloading and re-loading experiments. Two types of the aged material used for nearly 20 years as the roofing of the Forest Opera in Sopot (Poland) have been tested. The results have been separately obtained for the warp and fill di-rections. The comparative analysis has revealed that the material aged in service is more durable in the fill di-rection,...
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Impact of thermal loading into the structural performance of ships: A review
PublikacjaThe presented study reviews the recent advances done regarding the impact of thermal loading on the structural performance of ships. Firstly, the studies related to the mechanical and thermal properties of typical materials used in shipbuilding are outlined. Secondly, a brief introduction to the heat transfer analysis, Finite Element modelling and thermal stresses is provided. Finally, the review of papers dealing with the structural...
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Wet H2S corrosion and degradation of pipeline in amine regeneration system
PublikacjaThe paper presents the results of NDT examinations, metallographic tests and risk assessment of degradation related to corrosion of amine regeneration unit in a desulphurisation system. Intensive corrosion resulting from acid gases environment upon water condensation causes perforation of the pipeline. Detailed analysis reveals cracking related to the mechanism of wet H2S. Hydrogen penetration, resulting from the wet H2S process,...