An impedance study of two types of stainless steel in Ringer physiological solution containing complexing agentsMojca Slemnik
, Ingrid Milošev
, 2006, original scientific article
Abstract: The effect of complexing agents EDTA and citric acid on the electrochemical behaviour of AISI 304 and orthopaedic stainless steels in Ringer physiological solution was investigated by potentiodynamic polarization method and electrochemical impedance spectroscopy (EIS). The content of Mo has a pronounced effect on the corrosion resistance, as evident by the broader passive range of the orthopaedic stainless steel containing Mo. The addition of complexing agents induces significant changes in polarization and impedance characteristics, i.e., the shift of corrosion and breakdown potentials in a more negative direction, an increase in current density, and a significant decrease in charge transfer resistance. The results were interpreted by the formation of soluble complexes of metal ions with chelating agents, especially EDTA, which suppressed the formation of the outer Fe(III) layer of the passive film. The impact of complexing agent on the electrochemical parameters was found to be related to its concentration in electrolyte and the stability constant of the complex formed with the related metal ion.
Keywords: resistance, corrosion resistance, stainless steel, orthopedy, potentiodynamic polarization emthod, electrochemical impedance spectroscopy
Published: 31.05.2012; Views: 979; Downloads: 55
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Nucleation and growth of a passive film on AISI 420 martensitic stainless steel under potentiostatic conditionsRegina Fuchs-Godec
, Aljana Petek
, Valter Doleček
, 2002, original scientific article
Abstract: The kinetics of the early stage s of passive film formation on AISI stainless stell in mixtures of 0.1M ▫$H_2SO_4$▫ and 0.1M ▫$Na_2SO_4$▫, with pH-values of 2.42, 2.85 and 3.33, were studied at different anodic potentials. The potentiostatic step method was used as an electrochemical technique in which the anodic current density was measured as a function of time. For analysis of the measured data, the theory of "topochemical reaction" was applied for the charcterization of the exponent n in that part where the steepest current decay was observed. Through this theory, which includes the Erofeev equation, the number of conversion steps could be obtained, as well as the number of directions in which the nuclei grow. It was found that this theory can be successfully applied to the passivation process of AISI 420 stainles steel.
Keywords: corrosion, corrision resistance, martensitic stainless steels, passive films, potentiostatic step method, topochemical reactions
Published: 10.07.2015; Views: 749; Downloads: 44
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Novel chitosan/diclofenac coatings on medical grade stainless steel for hip replacement applicationsMatjaž Finšgar
, Amra Perva-Uzunalić
, Janja Stergar
, Lidija Gradišnik
, Uroš Maver
, 2016, original scientific article
Abstract: Corrosion resistance, biocompatibility, improved osteointegration, as well the prevention of inflammation and pain are the most desired characteristics of hip replacement implants. In this study we introduce a novel multi-layered coating on AISI 316LVM stainless steel that shows promise with regard to all mentioned characteristics. The coating is prepared from alternating layers of the biocompatible polysaccharide chitosan and the non-steroid anti-inflammatory drug (NSAID), diclofenac. Electrochemical methods were employed to characterize the corrosion behavior of coated and uncoated samples in physiological solution. It is shown that these coatings improve corrosion resistance. It was also found that these coatings release the incorporated drug in controlled, multi-mechanism manner. Adding additional layers on top of the as-prepared samples, has potential for further tailoring of the release profile and increasing the drug dose. Biocompatibility was proven on human-derived osteoblasts in several experiments. Only viable cells were found on the sample surface after incubation of the samples with the same cell line. This novel coating could prove important for prolongation of the application potential of steel-based hip replacements, which are these days often replaced by more expensive ceramic or other metal alloys.
Keywords: corrosion, corrosion resistance, chitosan, biocompatibility, biomaterials, biomedical materials, coatings, stainless steel
Published: 23.06.2017; Views: 637; Downloads: 206
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