Fizikalno-kemijska svojstva pasivnog sloja na žicama vodilicama u endourologiji

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.Glavni kriterij za primjenu austenitnog Cr-Ni-Mo čelika za žice vodilice u endourologiji je biotolerancija. Ovaj zahtjev ovisi o fizikalnim i kemijskim svojstvima površine žice, koja moraju biti prilagođena uvjetima koji vladaju u ljudskom urinarnom sustavu. Pogodnost predloženog pasivnog sloja za žicu vodilicu, prvenstveno ovisi o njegovom kemijskom sastavu. Stoga, istraživanje u ovom radu obuhvaća određivanje kemijskog sastava pasivnog sloja žice metodom fotoelektronske rendgentske spektroskopije (XPS). Otpornost na jamičastu koroziju određena je korištenjem potenciodinamičke polarizacije, snimanjem anodnih polarizacijskih krivulja

Komparativno istraživanje korozije žice korištene pri urološkoj obradi uz sterilizaciju

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.Svrha je ispitivanja bila da se ustanovi postoji li, i kakav je utjecaj sterilizacije na korozijsku otpornost žičanih uzoraka od nehrđajućeg čelika AISI 316L, oblikovanih plastičnom deformacijom različitog intenziteta. Ispitivanja su obavljena na uzorcima koji su elektrokemijski polirani kako bi se osigurala tražena niska hrapavost površine. U cilju procjene utjecaja sterilizacije na fizikalna i kemijska svojstva čelične površine, ispitivana je korozijska otpornost potenciodinamičkom metodom. Pritom je za simulaciju ljudske mokraće primijenjena zamjenska otopina. Snimljene krivulje anode polarizacije poslužile su za određivanje tipičnih parametara koji definiraju otpornost čelika prema jamičastoj koroziji, što je omogućilo procjenu korozijskog ponašanja čeličnih žica nakon sterilizacije

Corrosion resistance tests of magnesium alloy WE43 after extrusion

The purpose of the study was to evaluate resistance to electrochemical corrosion of magnesium alloy WE43 after plastic working. Potentiodynamic and immersion corrosion tests were performed in solutions with concentration of 0,01 – 2 M NaCl. The tests of microstructure of magnesium alloy after its exposure in NaCl solutions were performed with application of scanning microscope. The results of measurements of alloy surface topography were given, which were obtained by means of optical profile measurement gauge. The results of carried out tests prove explicitly that corrosion properties of extruded magnesium alloy WE43 deteriorate with the increase of molar concentration of NaCl solution. It was proved that irrespective of the concentration of the solution, WE43 alloy features pitting corrosion. It indicates the necessity to apply protective layers on the parts made of the tested alloy

Electrochemical behavior of guidewires made of X10CrNi 18-8 STEEL

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

Electrochemical characterisation of X10CrNi 18-8 steel in artificial plasma

Quality of applied guide wires conditions the course of treatment and its success to a great extent. In order to simulate conditions that can be found in blood vascular system samples were exposed to artificial blood plasma (T = 37 } 1 oC) for the time of 8 h. In order to obtain information regarding physical and chemical properties of modified surface of wire made of X10CrNi 18-8 steel, electrochemical impedance spectroscopy (EIS) test and tests of chemical composition of the surface layer X-ray photoelectron spectroscopy (XPS) were made. On the ground of performed EIS and XPS tests, favourable impact of steam sterilisation process on corrosion resistance of X10CrNi 18-8 steel was observed only for the case when chemical passivation was applied prior to sterilisation

Ocena własności fizykochemicznych i elektrochemicznych stali AISI 316L stosowanej na implanty w urologii

The main purpose of this study was to evaluate physicochemical and electrochemical properties of AISI 316L stainless steel with modified surface, used for implants in human urinary system. In order to simulate conditions, which occur in the tissue environment of the urinary system, the test pieces were exposed in a urinary solution at temperature of T=37 ±1ºC, for a period of 30 days. Evaluation of physicochemical properties of biomaterial was made on the basis of surface chemical analysis (XPS). To evaluate the effects which occur on the surface of the examined steel, Electrochemical Impedance Spectroscopy (EIS) method was also employed. Analysis of test results shows favourable influence of the suggested surface treatment of AISI 316L stainless steel. Samples having electrolytically polished and chemically passivated surface featured the best physicochemical and electrochemical characteristics.Podstawowym kryterium przydatności biomateriału metalowego na implanty urologiczne (stenty urologiczne) jest biokompatybilność. Jest ona w głównej mierze związana z własnościami fizykochemicznymi powierzchni implantu, które powinny być dostosowane do cech środowiska tkanek układu moczowego człowieka. W celu poprawy biokompatybilności stali Cr-Ni-Mo ustalono warunki wytwarzania warstw pasywnych na jej powierzchni. Wytworzenie warstwy pasywnej obejmowało etap polerowania elektrolitycznego i pasywowania. Taki sposób obróbki powierzchniowej zapewnił chropowatość Ra < 0,16 μm wymaganą dla tego rodzaju implantów. W pracy tej szczególną uwagę skoncentrowano na analizie długotrwałego oddziaływania środowiska sztucznego moczu na własności fizykochemiczne wytypowanej stali. Zasadniczym celem pracy była ocena własnosci fizykochemicznych i elektrochemicznych stali AISI 316L o modyfikowanej powierzchni stosowanej na implanty w układzie moczowym człowieka. W celu zasymulowania warunków występujących w środowisku tkankowym układu moczowego próbki poddawano ekspozycji w roztworze sztucznego moczu o temperaturze T=37±1ºC przez okres 30 dni. O przydatności zaproponowanej warstwy pasywnej do uszlachetniania powierzchni stali w znacznym stopniu decyduje jej skład chemiczny. Dlatego w pracy wykonano badania składu chemicznego metodą spektroskopii fotoelektronów (XPS), z użyciem wielofunkcyjnego spektrometru elektronów PHI 5700/660 firmy Physical Electronics, podczas których zidentyfikowano i wyznaczono stężenia atomowe pierwiastków w badanych warstwach pasywnych. Dla próbek przeprowadzono pomiar widma fotoelektronów w szerokim zakresie energii wiązania od 0÷1400 eV oraz dokładne pomiary linii widmowych poszczególnych pierwiastków składowych z warstwy powierzchniowej. Dla oceny zjawisk zachodzacych na powierzchni badanej stali zastosowano również metodę elektrochemicznej spektroskopii impedancyjnej (EIS). Pomiary przeprowadzono z wykorzystaniem systemu pomiarowego AutoLab PGSTAT 302N wyposażonego w moduł FRA2 (Frequency Response Analyser). Badania przeprowadzono w alternatywnym roztworze symulującym środowisko moczu człowieka. Zastosowana w pracy mikroskopia skaningowa pozwoliła na ocene stanu powierzchni stali AISI 316L przed i po ekspozycji w sztucznym moczu. Analiza wyników badań wskazuje na korzystny wpływ zaproponowanej obróbki powierzchniowej stali AISI 316L. Najkorzystniejszą charakterystykę fizykochemiczną i elektrochemiczną miały próbki o powierzchni polerowanej elektrolitycznie i pasywowanej chemicznie. Przeprowadzone w pracy badania stanowią podstawę do dalszych analiz związanych z zagadnieniem biokompatybilności stali Cr-Ni-Mo stosowanej na implanty w urologii

Electrochemical behavior of guidewires made of X10CrNi 18-8 STEEL

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

Electrochemical Corrosion of Magnesium Alloy AZ31 with Additive Lithium

The purpose of performed tests was evaluation of resistance to electrochemical corrosion of extruded magnesium alloy AZ31 with additive of 4.5% Li. Corrosion tests were performed in 0.01-2.0 M NaCl solutions. Potentiodynamic tests enabled to register polarisation curves. With application of stereoscopic microscope Nikon SMZ745T and electron scanning microscope Hitachi S-4200, the surface of the alloy was observed after immersion tests performed in 1-6 days. Results of performed tests prove explicitly deterioration of corrosion properties of the alloy with the increase of molar concentration of NaCl solution. It can be seen that corrosion process is intensive and that intensity increases with the increase of solution concentration and extension of exposure time