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Search Results: 1 - 10 of 297455 matches for " J. Szewczenko "
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Influence of bone union electrostimulation on corrosion of bone stabilizer in rabbits
J. Szewczenko
Archives of Materials Science and Engineering , 2007,
Abstract: Purpose: The aim of the work was determination of influence of the selected methods and parameters of bone union electrostimulation on corrosion of stainless steel implants coated with passive and passive-carbon layer.Design/methodology/approach: The semi-invasive and capacitively coupled electrical field methods of electrostimulation (without constant component) in rabbits were applied. The influence of electrostimulation on corrosion of implants was evaluated on the basis of the mass measurements and surface observations.Findings: On the basis of the research no corrosion on the implants stabilizing the bone fracture was observed.Research limitations/implications: Lack of visible and measurable corrosion requires the change of the methodology. Further research should be focused on the amount of metallic ions dissolved from the implants. Furthermore, it should be emphasized that the absence of corrosion of the electrostimulated implants is only one of many criteria describing the usefulness of electrostimulation parameters. The basic criterion is the biological effect obtained as the result of the electrostimulation.Practical implications: The obtained results are the basis for selection of methods and current parameters of the bone union electrostimulation in further clinical research. In case of positive results, the bone union electrostimulation with the use of implants coated with the passive and passive-carbon layers would be valuable method in treatment of pathological bone fractures.Originality/value: The paper is a continuation of the research on determining safe parameters of bone union electrostimulation of implants coated with the passive and passive-carbon layers.
Microstructure and corrosion resistance of CrAlSiN, CrAlSiN+DLC, and CrN coatings
K. Lukaszkowicz,W. Kwa?ny,J. Szewczenko
Journal of Achievements in Materials and Manufacturing Engineering , 2011,
Abstract: Purpose: The main aim of the research was the investigation of microstructure and corrosion resistance of the nanostructured CrAlSiN, CrAlSiN+DLC, CrN coatings deposited by cathodic arc evaporation method onto hot work tool steel substrate.Design/methodology/approach: Observations of surface and microstructure of the deposited coatings were carried out on cross sections in the SUPRA 35 scanning electron microscope. Diffraction and thin film microstructure were tested with the use of the JEOL JEM 3010UHR transmission electron microscope. X-ray study for the analyzed coatings was carried out using X′Pert PRO system. A phase identi cation of the investigated coatings was carried out in Bragg-Brentano geometry (XRD), and in grazing incidence geometry (GIXRD). Investigation of the electrochemical corrosion behaviour of the samples done in a PGP 201 Potentiostat/Galvanostat, using a conventional three-electrode cell. To simulate the aggressive media, 1-M HCl solution was used under aerated conditions and room temperature.Findings: It was found that the microstructure of the PVD coatings consisted of fine nanocrystallites, of an average size of 8 nm -13 nm, depending on the coating type. The morphology of the coatings fracture is characteristic of a dense microstructure. Basing on the GIXRD pattern of the investigated coatings, only fcc phases was encountered. The tests carried out with the use of a GDOS technique indicate the occurrence of a transition zone between the substrate material and the coating. Deposition of the PVD coatings increases the hardness of the tool steel surface up to 22-40 GPa. The CrN coated sample showed the best corrosion resistance.Practical implications: In order to evaluate with more detail the possibility of applying these nanocomposite coatings for protection of tool steels, further investigations should be undertaken in order to determine the thermal fatigue resistance of the coatings. The very good mechanical properties of the nanocomposite coatings make them potentially suitable for industrial applications.Originality/value: The results of the investigation provide useful information on microstructure and protective properties of the nanocomposite coatings on hot work tool steels.
Structure and corrosion resistance of aluminium AlMg2.5; AlMg5Mn and AlZn5Mg1 alloys
M. Kciuk,A. Kurc,J. Szewczenko
Journal of Achievements in Materials and Manufacturing Engineering , 2010,
Abstract: Purpose: The aim of the work was the evaluation of corrosion resistance and structure of aluminium AlMg2.5; AlMg5Mn and AlZn5Mg1 alloys.Design/methodology/approach: The corrosion resistance tests of investigated alloys were carried out by means of potentiodynamic method registering anodic polarization curves in 3.5% NaCl solution at room temperature. Registering anodic polarization curves was conducted at the potential rate equal to 1mV/s. As the reference electrode was used saturated calomel electrode (SCE) and the auxiliary electrode was platinum electrode. Mechanical properties were evaluated on the basis of Vickers hardness test. The test was realized with the use of Hauser hardness tester. The observations of the surface morphology after corrosive tests were carried out using Digital Scanning Electron Microscope DSM 940 OPTON.Findings: The investigations of corrosion resistance of examined aluminium alloys shows that the highest corrosion resistance in 3.5% NaCl solution was observed for AlZn5Mg1 aluminium alloy.Practical implications: The obtained results can be used for searching the appropriate way of improving the corrosion resistance of analysed alloys because better corrosion resistance, lightweight of aluminium and its alloys makes them as most attractive for the steel replacement in shipbuilding.Originality/value: The corrosion behaviour in chloride solution of AlMg2.5; AlMg5Mn and AlZn5Mg1 alloys was investigated.
Influence of bone union electrostimulation on corrosion of Ti6Al4V ELI alloy implants
J. Szewczenko,K. Nowińska,M. Basiaga
Journal of Achievements in Materials and Manufacturing Engineering , 2008,
Abstract: Purpose: The aim of the work was determination of influence of the selected methods of bone union electrostimulation on corrosion of Ti6Al4V ELI alloy implants.Design/methodology/approach: In vitro tests were carried out with the use of different methods of electrostimulation – invasive, semi-invasive and non-invasive. The alternating current without constant component was applied. The influence of electrostimulation on corrosion of implants was evaluated on the basis of the mass measurements and surface observations.Findings: On the basis of the research no significant corrosion on the samples was observed. Only local surface etching was observed, however it didn’t cause measurable change of mass. The presence of metallic ions in the solution was revealed.Research limitations/implications: Lack of visible and measurable corrosion requires the change of the methodology. Further research should be focused on the amount of metallic ions dissolved from the implants. Furthermore, it should be emphasized that the absence of corrosion of the electrostimulated implants is only one of many criteria describing the usefulness of electrostimulation parameters. The basic criterion is the biological effect obtained as the result of the electrostimulation.Practical implications: The obtained results are the basis for selection of methods and current parameters of the bone union electrostimulation in further clinical research (for stabilizing elements made of titanium alloys). Positive results of the in vitro research confirmed in tests in animals can enable further clinical tests. Positive results of the clinical tests could enable the bone union electrostimulation applied in pathological fractures in patients allergic to Cr. Allergy to Cr and Ni limits a wide use of implants made of Cr-Ni-Mo steel.Originality/value: The paper is a continuation of the research on determining safe parameters of bone union electrostimulation of implants made of stainless steel coated with the passive and passive-carbon layers.
Biomechanical analysis of plate stabilization on cervical part of spine
M. Kiel,J. Marciniak,J. Szewczenko,M. Basiaga
Archives of Materials Science and Engineering , 2009,
Abstract: Purpose: The main aim of the work was determination of biomechanical analysis of cervical spine – stabilizer system made of stainless steel (Cr-Ni-Mo) and Ti-6Al-4V alloy.Design/methodology/approach: To define biomechanical characteristic of the system the finite elements method (FEM) was applied. Geometric model of part of spine C5-C7 and stabilizer were discretized by SOLID95 element. Appropriate boundary conditions imitating phenomena in real system with appropriate accuracy were established.Findings: The result of biomechanical analysis was calculation of displacements and stresses in the vertebras and the stabilizer in a function of the applied loading: 50-300 N for the stabilizer made of stainless steel (Cr-Ni-Mo) and Ti-6Al-4V alloy.Research limitations/implications: The result of biomechanical analysis for plate stabilizer obtained by FEM can be use to determine a construction features of the stabilizer, and to select mechanical properties of metallic biomaterial and estimation of stabilization quality. The calculation of displacements for part C5-C7 show that the proposed type of stabilizer enables correct stabilization used to clinical apply.Practical implications: The results of biomechanical analysis showed correct mechanical properties used to made the plate stabilizer.Originality/value: The obtained numerical results should be verified in “in vitro” tests.
Wear investigations of tools used in bone surgery
J. Marciniak,Z. Paszenda,M. Kaczmarek,J. Szewczenko
Journal of Achievements in Materials and Manufacturing Engineering , 2007,
Abstract: Purpose: The main aim of the work was evaluation of wear rate of surgical drills used in orthopaedic procedureswith the use of plate bone stabilizers.Design/methodology/approach: The authors proposed a wear evaluation methodology of surgical drill edges.The drill wear was evaluated on the basis of measurement of point angle (2 κ) and wear land (VBB i VBBmax).The measurements were recorded for preselected number of holes n drilled in a bovine femur. Furthermore,structure investigations and hardness tests of surgical drills were performed.Findings: The investigations revealed diverse wear of the surgical drills. The main mechanism was the wear ofthe chamfered corner and chisel edge of the drills.Research limitations/implications: The improvement of service life of surgical drills can be achieved by thecorrect selection of heat treatment parameters, ensuring the desired geometry of edge and deposition of layerwhich ensure the significant increase of cutting edge hardness.Originality/value: The proposed methodology applied for surgical drills is an effective way of service lifeestimation. The quality of surgical tools influences the safety and the effectiveness of surgical procedures withthe use of plate stabilizers.
Numerical and experimental analysis of spine’s transpedicular stabilizer
M. Kiel,J. Marciniak,M. Basiaga,J. Szewczenko
Journal of Achievements in Materials and Manufacturing Engineering , 2010,
Abstract: Purpose: The aim of the work was a numerical and experimental analysis of spine’s transpedicular stabilizer on lumbar part of spine. The result of the analysis was determination of displacements of the stabilizers’ elements.Design/methodology/approach: To define numerical characteristic of the lumbar spine – transpedicular spine stabilizer system, the finite element method was applied. Geometrical models of lumbar part of spine and transpedicular stabilizer were discretized by SOLID95 element. The boundary conditions imitating phenomena in real system with appropriate accuracy were established. The experimental analysis was carried out for spine’s transpedicular stabilizers which were implanted on lumbar part of pig spine. The analysis was realized by means of testing machine MTS Insight with the use of videoextensometer. Numerical and experimental analysis were carried out for stabilizer made of stainless steel Cr-Ni-Mo. System was loaded by uniaxial compression with forces from 50 N to 1600 N.Findings: The result of analysis was calculation of relative displacements of the transpedicular stabilizer in a function of the applied loading; F = 700 - 1600 N for numerical model and F = 50 - 1600 N for experimental model.Research limitations/implications: The results of numerical analysis for transpedicular stabilizer obtained by finite element method were used to determine a construction features of the stabilizer, and to select mechanical properties of metallic biomaterial. The calculation of displacements for stabilizer show that the proposed type of stabilizer enables correct stabilization of spine.Practical implications: Both results of numerical and experimental analysis showed correct selection of mechanical properties of metallic biomaterial which were used to made the proposed type of transpedicular stabilizer.Originality/value: Advantageous results of analysis showed that the type of stabilizer may be used in clinical practice.
Electrochemical behavior of Ni-Ti alloy after surface modification
M. Kaczmarek,W. Simka,A. Baron,J. Szewczenko
Journal of Achievements in Materials and Manufacturing Engineering , 2006,
Abstract: Purpose: The shape memory effect and superelasticity make the nickel-titanium alloy an interesting material formedical applications. But the biocompatibility has been questioned due to conflicting results in the literature.The latest research has shown that this situation may be caused by a variation in NiTi surface treatment.The appropriate surface treatment increases the corrosion resistance. The paper presents the electrochemicalbehavior of NiTi alloy after surface modification with the use of various techniques.Design/methodology/approach: The evaluation of the electrochemical behavior of NiTi alloy was realizedboth by recording of anodic polarization curves with the use of the potentiodynamic method and by anelectrochemical impedance spectroscopy technique (EIS).Findings: Surface condition of metallic biomaterial determines its corrosion resistance. In the course of thework it was observed that the lowest values of corrosion current were recorded for the sterilized and thethermally passivated samples. The highest values of corrosion current were recorded for the ground samples.These samples obviously had also the highest corrosion rate.Research limitations/implications: The obtained results are the basis for the optimization of physicochemicalproperties of the metallic biomaterial. The future research should be focused on selected specific implantsspecially with respect to their application features.Practical implications: On the basis of the obtained results it can be stated that the suggested surface treatmentcan be applicable for medical implants due to the increase of the corrosion resistance and in consequence theincrease of biocompatibility.Originality/value: The paper presents the influence of various methods of the surface treatment on corrosionresistance of the NiTi alloy. The suggested methods can be applied in treatment of the material intended formedical applications especially in cases where the surface roughness plays important role.
New components of the mercury’s perihelion precession  [PDF]
J. J. Smulsky
Natural Science (NS) , 2011, DOI: 10.4236/ns.2011.34034
Abstract: The velocity of perihelion rotation of Mercury's orbit relatively motionless space is computed. It is prove that it coincides with that calculated by the Newtonian interaction of the planets and of the compound model of the Sun’s rotation.
Simple General Purpose Ion Beam Deceleration System Using a Single Electrode Lens  [PDF]
J. Lopes, J. Rocha
World Journal of Engineering and Technology (WJET) , 2015, DOI: 10.4236/wjet.2015.33014
Abstract: Ion beam deceleration properties of a newly developed low-energy ion beam implantation system were studied. The objective of this system was to produce general purpose low-energy (5 to 15 keV) implantations with high current beam of hundreds of μA level, providing the most wide implantation area possible and allowing continuously magnetic scanning of the beam over the sample(s). This paper describes the developed system installed in the high-current ion implanter at the Laboratory of Accelerators and Radiation Technologies of the Nuclear and Technological Cam-pus, Sacavém, Portugal (CTN).
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