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Search Results: 1 - 10 of 30997 matches for " Z. Paszenda "
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Use of coronary stents – material and biophysical conditions
Z. Paszenda
Journal of Achievements in Materials and Manufacturing Engineering , 2010,
Abstract: Purpose: The paper discusses application issues of using the metallic implants for treatment of the cardiovascular diseases. The analysis of the biophysical conditions of the heart – coronary vessels system has been used to distinguish the tissue environment properties which should be compatible with properties of the metal biomaterial and stent’s surface. On this basis the author presented results of experiments concerning the usefulness of the passive-carbon layer for surface treatment of vascular stents made of stainless steel.Design/methodology/approach: In order to determine the usefulness of the layer for implants in cardiology the following tests were carried out on the layer: structure, thickness, corrosion resistance, electrical properties and biocompatibility in experimental animals. The structure and thickness of the layer were tested in high resolution transmission electron microscope. Corrosion resistance was carried out by recording anodic polarization curves. Methodology of measurements took into consideration both implantation conditions and application of vascular stents. In tests concerning electrical properties of the layer, current-potential as well as capacity-potential characteristics were determined.Findings: The passive-carbon layer of nanocrystlline structure and high smoothness created on coronary stents’ surface fully ensures pitting corrosion resistance in both implantation and application conditions.Research limitations/implications: Deposition of the dielectric carbon layer on coronary stents’ made of stainless steel is effective method of reducing reactivity of their surface in blood environment and blood clotting in consequence.Originality/value: The need to determine the correct quality and properties of coronary stents was indicated. The properties refer to stents’ design, physio-chemical properties of the metallic biomaterial and its surface.
FEM analysis of drills used in bone surgery
Z. Paszenda,M. Basiaga
Archives of Materials Science and Engineering , 2009,
Abstract: Purpose: The aim of the work was determination of biomechanical analysis of a surgical drill – bone system in simulated conditions of drilling in a bone.Design/methodology/approach: Geometrical model of the selected surgical drill and simulated femur (cortical bone) was worked out in the Inventor Professional 2008. The value geometry of the edge was point angle (2κ1 = 90o and 2κ2 = 120o). Numerical model was prepared in ANSYS Workbench v. 11. Meshing was realized with the use of SOLID 187 elements. Evaluate boundary conditions to numerical analysis imitate phenomena in real system with appropriate accuracy. Drill was loaded with forces in the range F= 100-200 N and torqueT = 0.04 Nm. Calculations were carried out for two kinds of metallic material of the drill.Findings: The effect of numerical analysis was determination of strains and stresses in working part of the drill. Results of analysis indicate diverse values of strains and stresses distribution in working part of the drill depending on its geometry. The maximum values of strains and stresses were obtained for the drill of point angle 2κ1=120o.Research limitations/implications: In order to simulate phenomena in real system, a simplified model of surgical drill – femur system was worked out. The simplifications concerned mostly geometry of a femur. The femur was represented by disc of height h = 10 mm, corresponding with thickness of cortical bone.Originality/value: The numerical analysis of the surgical drill – femur system in simulated conditions of drilling in a bone can be a basis for optimization of cutting edge geometry of surgical tools as well as for selection of their mechanical properties.
Corrosion behaviour of Co-Cr-W-Ni alloy in diverse body fluids
W. Walke,Z. Paszenda,A. Ziebowicz
Archives of Materials Science and Engineering , 2007,
Abstract: Purpose: The aim of the work was evaluation of corrosion resistance of implantable Co-Cr-W-Ni alloy in simulated body fluids: human blood (artificial plasma), urine (artificial urine) and bone tissue (Tyrode solution).Design/methodology/approach: Corrosion resistance tests were carried out in the selected physiological body fluids at the temperature 37±1°C with the use of the Vo ltaLab PGP 201 system for electrochemical tests. The saturated calomel electrode (SCE) was applied as the reference electrode and the auxiliary electrode was a platinum foil. The evaluation of pitting corrosion was realized by recording of anodic polarization curves with the use of the potentiodynamic method. In order to evaluate crevice corrosion resistance the samples were polarized in the potential equal to 0,8 V by 900 seconds. Roughness of all the samples was evaluated with the use of the SURTRONIC 3+ (Taylor/Hobson) surface analyzer.Findings: Results of corrosion resistance tests of the Co-Cr-W-Ni alloy showed the diverse values of parameters obtained in the individual solutions. The suggested surface treatments ensure good crevice corrosion resistance of the Co-Cr-W-Ni alloy in all the tested physiological fluids.Research limitations/implications: The obtained results show the necessity of selection of the appropriate physiological solution, reflecting the specificity of body environment. In order to fully characterize the material in the human body environment, additional research on stress and fatigue corrosion should be carried out.Originality/value: The analysis of the obtained results show favorable influence of the suggested surface treatment of the Co-Cr-W-Ni alloy. Regardless of the selected physiological solution, the most favorable characteristics was observed for the electropolished and passivated samples.
Biomechanical behaviour of coronary stent design with OCC technology
W. Walke,Z. Paszenda,W. Jurkiewicz
Journal of Achievements in Materials and Manufacturing Engineering , 2007,
Abstract: Purpose: The work presents results of stresses and strains of three-layer vascular stent (Cr-Ni-Mo – Ta – Cr-Ni-Mo)and one-layer uniform one (Cr-Ni-Mo) used in operative cardiology.Design/methodology/approach: On the basis of the geometrical model a finite element mesh was generated.The discretization process was realized with the use of the SOLID95 element. The set boundary conditionsrepresented the phenomena which occur during balloon expanding.Findings: The numerical analysis of the three-layer stent showed diverse distribution of stresses and strains in theindividual layers. Minimum stresses in the analyzed range of expansion diameters (d = 2.25÷3.50 mm) were observedin the middle layer made of tantalum. Maximum stresses were observed in the layer made of the stainless steel.Research limitations/implications: Values of stresses and strains in different stents’ regions caused by applieddisplacements are valuable information for appropriate design of the geometry, hardening of the metallicbiomaterial and forming of physio-chemical properties of surface layer.Originality/value: The obtained results are valuable for selection of surface layer which is mainly responsiblefor ensuring proper hemocompatibility of the stent. The deformable surface layer is an effective way to reducethe surface reactivity of the stent in blood environment and in consequence coagulation.
Electrochemical investigations of Ti6Al4V and Ti6Al7Nb alloys used on implants in bone surgery
Z. Paszenda,W. Walke,S. Jadacka
Journal of Achievements in Materials and Manufacturing Engineering , 2010,
Abstract: Purpose: The subject of the research work is an analysis of surface roughness impact and the influence of the steam sterilisation process on physicochemical properties of samples made of Ti-6Al-4V and Ti-6Al-7Nb alloys after their exposure in a solution simulating the osseous environment.Design/methodology/approach: A surface roughness diversification of the samples made of Ti alloys was obtained with the aid of mechanical working – grinding and with the use of mechanical polishing. A corrosion resistance test was performed based on an anodic polarization curves recording. An Electrochemical Impedance Spectroscopy (EIS) method was used as well for assessment of the effects which occur on the surface of the examined alloys.Findings: The potentiodynamic studies showed favourable influence of steam sterilisation process (in an autoclave) on corrosion resistance of Ti alloys, regardless of the applied mechanical treatment. Exposition of the samples in Ringer’ solution caused further increase of corrosion resistance only for Ti-6Al-7Nb alloy. Analysis of impedance spectra showed presence of the capacitive passive layer for all tested variants.Research limitations/implications: Obtained results of potentiodynamic studies showed how a physicochemical condition of the samples surface, exposed to the solution simulating osseous system environment, was changing. In order to determine properties fully and surface structures of the Ti-6Al-4V and Ti-6Al-7Nb alloys after the sterilisation and the 60-day exposure to Ringer’ solution, impedance characteristics, obtained by means of EIS were determined. Differences of parameters describing electrical properties of the layers formed after the exposure to Ringer’ solution, are probably caused by a change of their chemical composition.Originality/value: The potentiodynamic and EIS studies of corrosion resistance in Ringer’ physiological solution allow to predict behaviour of Ti-6Al-4V and Ti-6Al-7Nb implants in osseous system environment.
Corrosion resistance of Cr-Ni-Mo steel after sterilization process
J. Marciniak,J. Tyrlik-Held,W. Walke,Z. Paszenda
Archives of Materials Science and Engineering , 2007,
Abstract: Purpose: The aim of the work was to evaluate how the process of high pressure steam sterilization influences the pitting corrosion resistance of Cr-Ni-Mo steel used for implants production.Design/methodology/approach: Surfaces of samples were prepared by electrolytic polishing and chemical passivation. Samples were sterilized in steam with the use of different parameters of temperature, pressure and time. Corrosion resistance investigations were carried out with the use of potentiodynamic method. The test were realized in solution simulating human blood environment (artificial plasma) at the temperature of 37±1oC and pH = 7.2. Parameters describing the corrosion resistance have been determined on the basis of analysis of anodic polarization curves.Findings: High pressure steam sterilization process improves all parameters relating to pitting corrosion resistance of Cr-Ni-Mo implantation steel that is: corrosion potential Ecorr, breakdown potential Eb, polarization resistance Rp, corrosion current density icorr and corrosion rate. The increase of sterilization time for constant parameters of temperature and pressure of steam was the important factor which improved significantly the corrosion resistance of tested samples.Research limitations/implications: Further investigations of chemical composition of the layers formed during sterilization process are planed.Originality/value: The obtained results show the advantageous influence of passivation and high pressure steam sterilization on the pitting corrosion resistance of Cr-Ni-Mo steel in solution simulating human blood environment (artificial plasma).
DLC coatings on martensitic steel used for surgical instruments
J. Marciniak,Z. Paszenda,W. Walke,M. Basiaga
Archives of Materials Science and Engineering , 2007,
Abstract: Purpose: The main aim of the work was evaluation of corrosion resistance, mechanical properties and topography of DLC coating formed by means of RF PACVD and magnetron method on the X39Cr13 martensitic steel used for surgical instruments.Design/methodology/approach: The corrosion resistance tests of samples were carried out by means of potentiodynamic method registering anodic polarization curves in physiological Tyrode’s solution at temperature 37±1oC. Registering of anodic polarization curves was conducted at the pace of potential change equal to 1 mV/s. As the reference electrode saturated calomel electrode (SCE) was, the auxiliary electrode was platinium electrode. Mechanical properties were evaluated on the basis of the Vickers hardness test. The test was realized with the use of the CSEM NHT hardness tester. The topography observations of the surface with the DLC coating by means of the confocal laser scanning microscope LEXT OLS3000 Olympus were carried out. The following surface treatments were applied: barrel finishing, chemical passivation and deposition of DLC coating by means of the RF PACVD and magnetron method.Findings: The investigations revealed diverse corrosion resistance and mechanical properties of the individual samples. The highest corrosion resistance was observed for the barrel finished, passivated and DLC coated samples obtained by means of magnetron method.Research limitations/implications: Usefulness of DLC coatings will be evaluated in further research in in vitro conditions. Furthermore wear a measurements of surgical drills coated with DLC layer (RF PACVD and magnetron method) will be carried out.Originality/value: The improvement of physico-chemical properties of surgical instruments made of martensitic steel will undoubtedly increase the safety of surgical procedures and reduce costs.
Biomechanical analysis of tibia – double threaded screw fixation
W. Walke,J. Marciniak,Z. Paszenda,M. Kaczmarek
Archives of Materials Science and Engineering , 2008,
Abstract: Purpose: The aim of the work was determination of biomechanical characteristics of a tibia – double threaded screw system with the use of finite element method.Design/methodology/approach: Geometrical model of the tibia was worked out on the basis of data from computer tomography of real bone. Geometrical model of the double threaded screw was prepared in ANSYS v. 11. Meshing was realized with the use of SOLID95 elements, applied in analyses of volumes. The model was loaded with forces in the range F = 100-2000 N.Findings: Initial biomechanical analysis, carried out with the use of finite element method, showed usefulness of the analyzed form of the double threaded screw made of Ti6Al4V alloy in fractured tibia treatment.Research limitations/implications: Due to applied simplifications of the tibia – double threaded screw fixation model, the analysis results should be experimentally verified in laboratory conditions.Originality/value: The obtained biomechanical characteristics of the tibia – double threaded screw system (u = f(F), σmax = f(F)) are the basis for selection of degree of strain hardening of the applied metallic biomaterial and optimization of geometrical features of the analyzed form of implant. Appropriate selection of mechanical properties and geometrical features of the implant is the main factor determining a stability of the fixation.
TiO2 and SiO2 layer deposited by sol-gel method on the Ti6Al7Nb alloy for contact with blood
W. Walke,Z. Paszenda,P. Karasiński,J. Marciniak
Archives of Materials Science and Engineering , 2012,
Abstract: Purpose: The study contains the analysis of TiO2 and SiO2 surface modification impact on physical and chemical characteristics of Ti-6Al-7Nb alloy samples in the solution simulating cardiovascular system.Design/methodology/approach: Sol-gel coatings were selected on the ground of data taken from literature. The base of stock solution consisted of silicon dioxide precursor SiO2 (TEOS) and titanium oxide precursor TiO2. Application of SiO2 and TiO2 coating on the surface of Ti alloy was preceded by mechanical working – grinding (Ra = 0.40 μm) and mechanical polishing (Ra = 0.12 μm). Corrosion resistance tests were performed on the ground of registered anodic polarisation curves and Stern method. Electrochemical Impedance Spectroscopy (EIS) was also used in order to evaluate phenomena taking place on the surface of the tested alloys. The tests were made in artificial blood plasma at the temperature of T = 37.0±1°C and pH = 7.0±0.2.Findings: Test results obtained on the ground of voltamperometric and impedance tests showed that electrochemical characteristics of Ti-6Al-7Nb alloy differs relative to the type of surface treatment. Practical implications: Potentiodynamic and EIS studies of corrosion resistance in artificial plasma enable to predict the behavior of modified Ti-6Al-7Nb implants in cardiovascular system. The topic proposed in the article is favourable for the development of entrepreneurship sector due to high demand on such technologies and relatively easy implementation of obtained laboratory test results in the industrial and clinical practice.Originality/value: Suggestion of proper surface treatment variants that incorporate sol-gel method is of perspective significance and will help to develop technological conditions with specified parameters of oxide coating creation on the surface of metallic implants.
Corrosion resistance and chemical composition investigations of passive layer on the implants surface of Co-Cr-W-Ni alloy
W. Walke,Z. Paszenda,J. Tyrlik-Held
Journal of Achievements in Materials and Manufacturing Engineering , 2006,
Abstract: Purpose: The paper presents results of corrosion resistance and surface properties of Co-Cr-W-Ni alloy used in interventional cardiology.Design/methodology/approach: The tests were carried out on grinded, electropolished and passivated samples. The pitting corrosion tests were realized by recording of anodic polarization curves with the use of the potentiodynamic method. The saturated calomel electrode (SCE) of KP-113 type was applied as the reference electrode. The tests were carried out in electrolyte simulating human blood environment (artificial plasma). Crevice corrosion resistance was carried out in accordance to the ASTM F-746-81:1999 standard. Chemical composition investigations of the passive layer were realized with the use of multifunctional electron spectrometer Physical Electronics PHI 5700/660. The X-ray photoelectron spectroscopy with monochromatic radiation AlKα of 1486,6 eV was applied.Findings: Results of electrochemical tests have revealed the influence of surface preparation of the Co-Cr-W-Ni alloy on the corrosion resistance. The tests carried out in the artificial plasma for the grinded, the electropolished and the chemically passivated samples have showed that Co-Cr-W-Ni alloy is resistant to both crevice and pitting corrosion. The chemical composition analysis of the passive layer on Co-Cr-W-Ni alloy has revealed the presence of the following elements: C, O, N, Cr, Fe, Co, Ni and W.Research limitations/implications: The research was carried out on samples, not on final elements. The tests were carried out in in vitro conditions. Practical implications: The suggested surface treatment can be used for implants made of the Co-Cr-W-Ni alloy.Originality/value: The proposed surface treatment ensures the increase of the corrosion resistance in the blood environment that increases biocompatibility.
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