Florica Simescu

Publications (2)1.49 Total impact

• Article: In situ monitoring of zinc phosphate coating formation on mild steel by acoustic emission technique

  Florica Simescu, Hassane Idrissi
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  ABSTRACT: In the present work, an acoustic emission (AE) technique, along with potential electrode measurements, is used to study the zinc phosphate coating formation obtained on mild steel by cathodic electrochemical treatment (−15 mA cm−2) at ambient temperature. The AE activity recorded during the phosphate coating formation shows evident links between this activity and the coating parameters such as the potential electrode and coating weight. The principal component analysis (PCA) of AE parameters reveals the presence of three well-separated populations denoted A, B and C. These populations (A, B and C) show peak frequencies <180 kHz, between 214 and 260 kHz, and 280 and 320 kHz, respectively. The energy of the B and C populations is lower than that of A population and the rise time of B population is much longer than that recorded for the populations A and C. These events were respectively attributed to the evolution and release of dihydrogen bubbles, the formation and growth of the phosphate layer, and the stress release generated by the dihydrogen bubbles trapped in the coating pores.
  Measurement Science and Technology 03/2009; 20(5):055702. · 1.49 Impact Factor
• Article: Corrosion behaviour in alkaline medium of zinc phosphate coated steel obtained by cathodic electrochemical treatment

  Florica Simescu, Hassane Idrissi
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  ABSTRACT: The present work evaluated the ability of zinc phosphate coating, obtained by cathodic electrochemical treatment, to protect mild steel rebar against the localized attack generated by chloride ions in alkaline medium. The corrosion behaviour of coated steel was assessed by open circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy. The chemical composition and the morphology of the coated surfaces were evaluated by X-ray diffraction and scanning electron microscopy. Cathodically phosphated mild steel rebar have been studied in alkaline solution with and without chloride simulating the concrete pore solution. For these conditions, the results showed that the slow dissolution of the coating generates the formation of calcium hydroxyzincate (Ca(Zn(OH)3)2·2H2O). After a long immersion time in alkaline solution with and without Cl−, the coating is dense and provides an effective corrosion resistance compared to mild steel rebar.
  Corrosion Science.