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This paper describes the use of a combination of two specific layers to protect the surface of low–carbon steel against electrochemical corrosion phenomena, which has not been published in the scientific literature so far. The layers include a black oxide film and siloxane coating, which are formed in the steel blackening and sol–gel processes, respectively. The so–obtained samples were subjected to surface morphology and physicochemical analysis (atomic force microscopy and Fourier-transform infrared spectroscopy) as well as electrochemical measurements, including AC and DC techniques. The physicochemical and surface morphology analysis allowed to prove the presence and adhesion of the siloxane coating to the surface of the black oxide layer, while the results of the electrochemical tests show that low–carbon steel modified this way is characterized by remarkable anti–corrosive properties, comparable to those of stainless steel. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Objectives: In recent years there has been an increase in the use of dental casting alloys in prosthodontic treatment. Many patients have metals or alloys, as well as amalgam fillings, in their mouth, and will have them for many years. The aim of this study was to evaluate and compare, in vitro, the galvanic corrosion behavior of chromium–cobalt alloy (Remanium GM 380) and chromium–nickel alloy (Remanium CS) when bound together or coupled with silver-based amalgam (Amalcap plus). Methods: An electrochemical characterization of the alloys was performed by potentiostatic and potentiodynamic methods, i.e. the open circuit potential (OCP), the corrosion potential (E CORR), corrosion current density (i CORR) and corrosion resistance (R P). The electromotive force (EMF) of the bimetallic cells was also tested. Electroanalytical techniques were used to estimate the release of any respective element from the dental alloys under study into the artificial saliva solution. Results: It was found that a bimetallic cell consisting of Remanium CS and Remanium GM 380 alloys has a very low EMF (a few mV) and is not a potential source of galvanic currents in the oral cavity. However, galvanic cells prepared from Amalcap plus and Remanium CS or Remanium GM 380 showed a much greater EMF: 104 and 109mV, respectively. This clearly indicates that in these latter cases it is possible to expect some metal ions in the saliva solution as a result of the work of galvanic currents. It was found, by adsorptive stripping voltammetry analysis, that nickel or cobalt, depending on the alloy used, appeared in the saliva solution and increased in concentration over time. Significance: The results indicate that the correct design and use of dental alloys are important when determining the appropriate treatment for a specific patient. [Copyright &y& Elsevier]