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Search Results: 1 - 10 of 84432 matches for " W. Walke "
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Physicochemical properties of passive layer on the surface of guide wire used in endourology
W. Walke,J. Przondziono
Metalurgija , 2011,
Abstract: The main criterion for austenitic steel X2CrNiMo 17-12-2 suitability for guide wire in endourology is its biotolerance. It is most of all connected with physical and chemical properties of wire surface, which should be adjusted to the characteristics of the environment of human urinary system tissues. Suitability of the proposed passive layer for purification of wire surface was determined to a great extent by its chemical composition. Therefore, this study included chemical composition tests by means of X-ray Photoelectron Spectroscopy (XPS), during which atomic concentration of elements in tested passive layers was identified and determined. Resistance to pitting corrosion was evaluated on the ground registered anodic polarisation curves by means of potentiodynamic method.
A comparative study of the corrosion of wire used in urological treatment under sterilization
W. Walke,J. Przondziono
Metalurgija , 2012,
Abstract: The purpose of the tests was to determine whether and how sterilization process of samples made of AISI 316L stainless steel with different strain impacts their corrosion resistance. Tests were made on steel samples that had been electrochemically polished in order to assure proper surface roughness. In order to evaluate the influence of sterilization on physical and chemical properties of steel surface, tests of corrosion resistance were made by means of potentiodynamical method. The tests were made in alternative solution simulating human urine. Recorded anodic polarization curves created the ground for determination of typical parameters describing pitting corrosion resistance, that enabled to evaluate steel wire corrosion behavior under sterilization conditions.
Electrochemical behavior of guidewires made of X10CrNi 18-8 STEEL
W. Walke,J. Przondziono
Metalurgija , 2013,
Abstract: The purpose of this study was to evaluate corrosion resistance of wires with differentiated of surface preparation and with differentiated work hardening, used in low-invasive cardiology in sterile environment. The study is devoted to voltamperometric and impedance tests, which were used to determine typical features describing corrosion resistance. Measurement system PGSTAT 302n together with a set of measurement electrodes were used for the tests. The tests were carried out in artificial blood plasma at the temperature of T = 37 °C. Obtained results were used as the ground for selecting the way of preparation of the surface of X10CrNi 18-8 steel in order to improve its biotolerance in blood environment.
Potentiodynamic studies of stainless steel wire for endourology
J. Przondziono,W. Walke
Archives of Materials Science and Engineering , 2009,
Abstract: Purpose: The purpose of the study is to evaluate resistance to electrochemical corrosion of wire made of Cr-Ni stainless steel, designed for use in endourological treatment. The influence of strain formed in the process of drawing and methods of wire surface preparation to corrosive resistance in artificial urine solution were analysed.Design/methodology/approach: Wire corrosion tests were carried out in the solution of artificial urine with the use of the system for electrochemical tests VoltaLab PGP201. Resistance to electrochemical corrosion was evaluated on the ground of recorded curves of anodic polarization by means of potentiodynamic method. Mechanical properties of wire were tested by means of static uniaxial tension test.Findings: Potentiodynamic tests carried out in artificial urine enabled to determine how the resistance to pitting corrosion of wire changes, depending on strain formed in the drawing process as well as on the method of wire surface preparation. Deterioration of corrosive properties of wire along with the increase in the formed strain hardening was observed.Research limitations/implications: The obtained test results proved the suitability of the applied research methodology for evaluation of electrochemical corrosion resistance of wire made of stainless steel designed for use in endourology.Practical implications: Test results are of significant utilitarian value because they can determine the relation between pitting corrosion resistance and the volume of strain formed in the wire drawing process, and consequently their mechanical properties.Originality/value: The analysis of the results of electrochemical corrosion resistance tests showed positive impact of wire surface treatment by means of electrolytic polishing and chemical passivation method on improvement of its corrosive properties. It must be emphasised that despite the increase in corrosion resistance, obtained thanks to surface treatment, it is necessary to use protective coating on wire used in urology.
Physicochemical properties of Cr-Ni-Mo steel and Co-Cr-W-Ni alloy applied in urology
W. Walke,J. Przondziono
Journal of Achievements in Materials and Manufacturing Engineering , 2010,
Abstract: Purpose: The main purpose of this study was to evaluate physical and chemical properties of Cr-Ni-Mo steel and Co-Cr-W-Ni alloy with modified surface, used for implants in human urinary system.Design/methodology/approach: Evaluation of physical and chemical properties of biomaterials was made on the ground of corrosion resistance tests and analysis of chemical composition of surface layer. Resistance to pitting corrosion was evaluated on the ground registered anodic polarisation curves by means of potentiodynamic method. Chemical composition investigations of the passive layer have been carried out with the use of X-ray Photoelectron Spectroscopy (XPS).Findings: Obtained test results show more favourable physical and chemical characteristics of Co-Cr-W-Ni alloy when compared to Cr-Ni-Mo steel. Suggested processes of surface treatment guarantee the improvement of corrosion resistance, and hence – biocompatibility of both metallic biomaterials in artificial urine.Research limitations/implications: Obtained test results indicate the necessity to select such physiological solution for corrosion tests, that would reflect specificity of the environment in which the implant will be functioning. Complementation of presented tests with measurements of stress and fatigue corrosion resistance will enable complex evaluation of behaviour of those biomaterials in urinary system environment.Practical implications: Analysis of test results shows favourable influence of suggested surface treatment of Co-Cr-W-Ni alloy. Samples with electrolytically polished and chemically passivated surface featured the best physical and chemical characteristics.Originality/value: After 30 days’ exposure in artificial urine solution passive layer created on the surface of Co-Cr-W-Ni alloy has better combination of physical and chemical properties than passive layer created on steel.
Chemical composition of passive layers formed on metallic biomaterials
M. Kaczmarek,W. Walke,W. Kajzer
Archives of Materials Science and Engineering , 2007,
Abstract: Purpose: In the paper the results of chemical composition investigations of passive layers formed on implants made of Cr-Ni-Mo steel, Co-Cr-W-Ni alloy and Ni-Ti alloy have been presented.Design/methodology/approach: Chemical composition investigations of the passive layer have been carried out with the use of X-ray Photoelectron Spectroscopy (XPS). The X-ray photoelectron spectroscopy with monochromatic radiation AlKα of 1486,6 eV was applied. The tests were carried out on the samples of polished as well as polished and passivated surfaces. The measurement of photoelectron spectrum in the wide range of binding energy from 0-1400 eV and precise measurements of the spectrum lines of elements from the surface layer were conducted.Findings: The chemical composition analysis of passive layers on the Cr-Ni-Mo steel, the Co-Cr-W-Ni alloy and the Ni-Ti alloy has revealed the presence of the following elements: (C, N, O, Na, Mg, Ca, Cr, Fe, Ni), (C, O, N, Cr, Fe, Co, Ni, W) and (C, N, O, Na, Si, S, Cl, K, Ca, Ti, Ni) respectively.Research limitations/implications: The research was carried out on samples, not on final parts. The tests were carried out in in vitro conditions. The obtained results are promising however further studies, in particular in blood environment, will determine a usefulness of the suggested technique of stents’ surface improvement.Originality/value: The obtained results show the usefulness of the applied surface treatment to refine surfaces of implants made of the Cr-Ni-Mo steel, the Co-Cr-W-Ni alloy and the Ni-Ti alloy.
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.
Stresses present in bone surrounding dental implants in FEM model experiments
J. ?mudzki,W. Walke,W. Chladek
Journal of Achievements in Materials and Manufacturing Engineering , 2008,
Abstract: Purpose: Appropriate selection of material and geometric characteristics of intraosseus pillar implant part creates a possibility to control the bone tissue loading.Design/methodology/approach: A basic tool that is commonly used the evaluation of bone loading state is the linear FEM analysis. It requires setting of appropriate experiment conditions. Hence, an analysis has been carried out in order to determine the influence of dividing method of finite elements (tetragonal type 187 in Ansys system v.11) on stresses in pillar and surrounding bone tissue.Findings: Seeking of loading values cortical bone tissue is highly affected by the increase of mesh density on the edge of implant insertion into the cortex bone. Loading stresses values have significantly increased along with increased mesh density, whereas the differences have even reach 47 MPa.Research limitations/implications: Research has been carried out only for the Ansys system in the linear range assuming standard shape and mechanical characteristics of implant and bone, as well as regarding the after the osseointegration phase because if the presumed complete adherence of the pillar to the bone.Practical implications: Excessive increase of mesh density leads to overestimation of loading stresses values and further to an unjustified increase of pillars’ diameter. At the other hand, too large elements might lead, through an underestimation of loading stress level, to overloading atrophy of bone tissue.Originality/value: This paper points out the necessity of more determined activities aimed on defining appropriate and uniform FEM experiment conditions that would enable achievement of more real results of model researches and their comparability.
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.
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.
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