Прегледај по Аутор "Riđošić, Marija"

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    Ceria Particles as Efficient Dopant in the Electrodeposition of Zn-Co-CeO2 Composite Coatings with Enhanced Corrosion Resistance: The Effect of Current Density and Particle Concentration
    (MDPI, 2021) Riđošić, Marija; Bučko, Mihael; Salicio-Paz, Asier; García-Lecina, Eva; Živkovic, Ljiljana S.; Bajat, Jelena B.
    Novel Zn-Co-CeO2 protective composite coatings were deposited successfully from chloride plating solutions. Two different types of ceria sources were used and compared: commercial ceria powder and home-made ceria sol. Electrodeposition was performed by a direct current in the range of 1–8 A dm􀀀2. Two different agitation modes were used and compared, magnetic stirring and ultrasound-assisted stirring (US). The influence of magnetic stirring on the stability of the related plating baths was evaluated via a dynamic scattering method. The results pointed to better stability of the prepared ceria sol. The morphology of the composite coatings was examined by scanning electron microscopy (SEM), and particle content was determined by energy-dispersive X-ray spectroscopy (EDS). The results showed that the increase in the deposition current density was not beneficial to the coating morphology and particle content. The corrosion behavior of the Zn-Co-CeO2 composite coatings was analyzed and compared by electrochemical impedance spectroscopy and polarization resistance. The ultrasound-assisted electrodeposition at small current densities was favorable for obtaining composite coatings with enhanced corrosion stability. The protection was more effective when US was applied and, additionally, upon utilization of ceria sol as a particle source, which was revealed by higher polarization resistance and greater low-frequency impedance modulus values for sol-derived composite coatings deposited under ultrasound.
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    Hardness and corrosion resistance of Zn−Mn/Al2O3 composite coatings produced by electrochemical deposition
    (National Institute of Science Communication and Policy Research (CSIR-NIScPR), 2022) Bučko, Mihael; Riđošić, Marija; Kovačina, Jovanka; Tomić, Milorad V.; Bajat, Jelena B.
    The aim of this study is development and characterization of the novel Zn-Mn/Al2O3 composite coatings. The coatings were electrodeposited with constant current density on steel, from chloride solution, without any commercial additives. The Zn−Mn alloy coatings that show high corrosion resistance, may be used in future as an alternative to cadmium coatings. However, the pure Zn and Zn alloy coatings are characterized with poor mechanical properties. Therefore, in this work the alumina particles were incorporated into the Zn-Mn matrix, and the hardness and corrosion resistance of the obtained composite coatings were tested. The mechanical and ultrasound agitation were used to achieve good dispersion of plating solution and homogeneous co-deposition of second phase. The goal was to examine the effect of the agitation type in bath, on the attributes of the deposited composite coatings. The incorporation of Al2O3 particles was enhanced when the mechanical agitation of the solution was applied. However, in case that this agitation method was used, the agglomeration of the alumina particles occurred. In contrast, when an ultrasonic agitation of the plating solution was applied, the uniform distribution of the alumina particles could be achieved. The presence of particles in the matrix, along with applied ultrasound, resulted in grain refinement and homogeneous microstructure. The Al2O3 nanoparticles incorporated in Zn-Mn alloy matrix, resulted in a significant increment in the indentation hardness and a modest increase in the coating corrosion resistance. However, the coating hardness increased with alumina addition, only in case when an ultrasonic agitation of the electrodeposition solution was used.
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    Zn-Co-CeO2 vs. Zn-Co Coatings: Effect of CeO2 Sol in the Enhancement of the Corrosion Performance of Electrodeposited Composite Coatings
    (MDPI, 2021) Riđošić, Marija; Nikolić, Nebojša D.; Salicio-Paz, Asier; García-Lecina, Eva; Živković, Ljiljana S.; Bajat, Jelena B.
    Electrodeposition and characterization of novel ceria-doped Zn-Co composite coatings was the main goal of this research. Electrodeposited composite coatings were compared to pure Zn-Co coatings obtained under the same conditions. The effect of two ceria sources, powder and home-made sol, on the morphology and corrosion resistance of the composite coatings was determined. During the electrodeposition process the plating solution was successfully agitated in an ultrasound bath. The source of the particles was found to influence the stability and dispersity of plating solutions. The application of ceria sol resulted in an increase of the ceria content in the resulting coating and favored the refinement from cauliflower-like morphology (Zn-Co) to uniform and compact corallike structure (Zn-Co-CeO2 sol). The corrosion resistance of the composite coatings was enhanced compared to bare Zn-Co as evidenced by electrochemical impedance spectroscopy and scanning Kelvin probe results. Zn-Co doped with ceria particles originating from ceria sol exhibited superior corrosion resistance compared to Zn-Co-CeO2 (powder) coatings. The self-healing rate of artificial defect was calculated based on measured Volta potential difference for which Zn-Co-CeO2 (sol) coatings exhibited a self-healing rate of 73.28% in a chloride-rich environment.