Dimensional Changes, Microstructure, Microhardness Distributions And Corrosion Properties Of Iron And Iron-Manganese Sintered Materials

Iron samples and Fe-Mn alloys with Mn content of 25 wt.% and 30 wt.% were prepared by blending, compressing and sintering with the aim to study their dimensional changes, microstructure, microhardness distribution and primarily the electrochemical corrosion behaviour in a simulated body environment

Zmiany wymiarowe, mikrostruktura, rozkład mikrotwardości i własności korozyjne spiekanych materiałów żelazo oraz żelazo-mangan

Iron samples and Fe-Mn alloys with Mn content of 25 wt.% and 30 wt.% were prepared by blending, compressing and sintering with the aim to study their dimensional changes, microstructure, microhardness distribution and primarily the electrochemical corrosion behaviour in a simulated body environment. The light microscopy (LM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and micro-hardness measurements revealed a microheterogeneous multiphase structure of sintered Fe-Mn samples. The potentiodynamic tests have demonstrated that the corrosion rates of such Fe-Mn alloys immersed in Hank’s solution were higher than those for a pure iron, and also higher than the rates reported for homogeneous Fe-Mn alloys.Próbki żelazne oraz stopy Fe-Mn, zawierające 25 i 30% mas. Mn, przeznaczone na biomateriały, zostały przygotowane na drodze mielenia, prasowania oraz spiekania w celu zbadania ich zmian wymiarowych, mikrostruktury, rozkładu mikrotwardości oraz odporności korozyjnej w skumulowanych w warunkach laboratoryjnych, panujących w ciele człowieka. Badania z wykorzystaniem mikroskopii optycznej i skaningowej, wraz z EDX oraz pomiary mikrotwardości ujawniły mikroniejednorodność wielofazowej struktury spiekanych stopów Fe-Mn. Testy potentiometryczne wykazały, że współczynniki korozji spieków Fe-Mn były wyższe niż spieków wykonanych z czystego żelaza oraz z jednorodnych stopów Fe-Mn

Monitoring of Silver Electrodeposition onto HOPG Electrodes in the Presence of Picolinic Acid by in Situ Surface-Enhanced Raman Spectra Measurements

In situ surface-enhanced Raman spectra (SERS) have been recorded during silver potentiodynamic electrodeposition onto HOPG electrodes from solutions containing silver perchlorate and picolinic acid (PA). Modification of the composition and pH of the electrolyte has allowed us to achieve an adequate control of the electroactive species distribution in solution. The adsorption behavior of different PA species on silver growing crystallites has been studied by using the potential dependence of SERS signals. Analysis of the vibrational bands from additive molecules has allowed us to establish that at pH > 3.0 the PA anion is the most stable species on the electrode surface, whereas the predominant species in solution is the zwitterion. At pH 0.3, adsorption of zwitterion and anion species onto the silver surface, even though the PA cation is predominant in the solution, has been evidenced. For all the SERS spectra it was possible to infer the adsorption geometry and the ClO4– ion coadsorption. Detection of intensified signals of the adsorbed additive is facilitated by the morphological characteristics of the particles (globular flower-like structures), which results to be a good active SERS substrate on the HOPG electrodes. Spectroelectrochemical experiments are correlated with the SEM micrographs of the silver crystallites.Fil: Vazquez, Cecilia Irene. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Andrade, Gustavo F. S.. Universidade Federal de Juiz de Fora; BrasilFil: Temperini, Marcia L. A.. Universidade de Sao Paulo; BrasilFil: Lacconi, Gabriela Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin