Browsing by Author "Kiradzhiyska D."

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    Evaluation of the electrochemical performance of Ag containing aao layers after extended exposure to a model corrosive medium
    (2020-01-01) Kozhukharov S.; Girginov C.; Kiradzhiyska D.; Tsanev A.; Avdeev G.
    The coating procedure appears to be an indispensable finishing stage in the production of Al based industrial products, engineering facilities and equipment. For this reason, there is an ever-increasing interest towards the elaboration of reliable corrosion protective layers with apparent coverage, adhesion, and barrier properties. In this sense, both the formation of anodized aluminum oxide (AAO) layer and its further modification with silver enable the elaboration of advanced (Al-O-Ag) films with extended beneficial characteristics. The present research activities are aimed at the determination of the corrosion protective properties of electrochemically synthesized Al-O-Ag layers on the technically pure AA1050 alloy. The structures and compositions of the obtained Al-O-Ag layers were characterized by X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). The research activities were accomplished by means of two independent electrochemical characterization methods: electrochemical impedance spectroscopy (EIS) and potentiodynamic scan-ning (PDS). The electrochemical measurements were performed after 24, 168 and 672 hours of exposure to 3.5 % NaCl solution used as a model corrosive medium (MCM), in order to determine the barrier properties and durability of the elaborated Al-O-Ag layers. The analysis of the obtained results has undoubtedly shown that the proposed electrochemical Al-O-Ag layer formation can successfully be used for the creation of self-standing layers with apparent corrosion protective properties. Besides, Al-O-Ag system can be used as a basis for development of efficient protective layers suitable for application in biologically contami-nated media.
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    Optical and color characteristics of porous alumina with electrochemically incorporated silver
    (2018-01-01) Kiradzhiyska D.; Mantcheva R.; Girginov C.; Kozhukharov S.
    Following the ever increasing interest towards the combination between aluminum anodization and incorporation of relatively affordable metals, a brief study was performed on the impact of the duration of AC-electrochemical incorporation of silver on the resulting optical properties and color characteristics. The experiments performed on technically pure aluminum included: anodization in galvanostatic regime; AC-electrochemical silver incorporation, characterization of the optical properties by light reflectance and refractive colorimetric measurements. This systematic study enabled to determine some correlation between the coloring process duration and the resulting optical and color features.