*2.3. Characterization of Coated Specimens and Protective Properties*

Four types of specimens were tested in both salt spray and electrochemical experiments: (a) blank (not coated); (b) coated with pristine glassy epoxy polymer; (c) and (d) coated with the two types of epoxy-clay nanocomposites, i.e., with I.28E and I.30E organoclays. The times of exposure were 1, 2, or 4 days. The salt spray tests were carried out in a corrosive environment of 100% saturated moisture + 5 wt % NaCl solution, according to Standard Methods (ASTM B117) [23,24]. For each tested specimen the weight loss/gain during the exposure in the corrosive environment was measured and the corrosion behaviour was examined by optical and microscopic (scanning electron microscopy) investigation. Three specimens were prepared for each salt spray test. Each tested specimen was washed in clean running water to remove salt deposits from their surface, dried, and weighted, according to ASTM standard B117 [23]. Different specimens were used for the calculation of the corrosion weight loss at 1 or 4 days. After exposure for 1, 2, or 4 days in a corrosive environment of 3.5% NaCl solution, electrochemical impedance spectroscopy measurements were carried out according to Standard Methods (ASTM G106, ASTM B457) [25,26]. Impedance measurements in the controlled potential mode were performed with a system consisting of an impedance spectrum analyzer (Zahner Elektrik IM6, potensiostat DC ±10 V, ±3 A, frequency generator and analyzer, Zahner Elektrik GmbH & Co. KG, Kronach, Germany) connected in serial to a PC terminal computer. We used the THALES evaluation software (Zahner Elektrik GmbH & Co. KG) that runs under the TASC system (Zahner Elektrik GmbH & Co. KG) and combines the MS-DOS system (Microsoft) of the PC terminal with the AMOS/ANDI data acquisition system (Zahner Elektrik GmbH & Co. KG) in a IM6 unit. The frequency scan was carried out over a range from 10,000 Hz (10 kHz) to 0.1 Hz (100 MHz). In all the measurements, ten frequency points per decade were taken and the potential amplitude was 10 mV. A conventional 3 compartment glass cell was used. A platinum foil with a surface area of 2 cm2 was used as the counter electrode. A fritted glass separated the anodic compartment. A saturated calomel reference electrode was placed close to the cathode through a Luggin capillary. The supporting electrolyte was 0.1 M LiClO4. All impedance measurements were carried out at 25 ◦C, in de-aerated conditions and at the potential value of the corrosion potential (*Ecorr*). The open circuit potential (OCP) for all types of specimens and times of exposure also was determined.

## **3. Results and Discussion**
