**3. Conclusions**

26 Corrosion Resistance

Where Z is the total impedance, Rb is the barrier layer resistance of anodization, Rp is the porous layer resistance of porous layer of anodized aluminum, CPE is the constant phase element of the porous layer, Rc is the coating resistance, and Rs is the solution resistance.

Soaking three spraycoated Y2O3 on anodized aluminum in 3.5wt% NaCl solution for 7 days, the EIS data are shown in Fig.29. The EIS data indicate that samples coated at different time have the similar overall impedance and the quality control of coating process is consistent. The complete analysis of the EIS data using a three-time constant interface model is shown

10-3 10-2 10-1 10<sup>0</sup> 10<sup>1</sup> 10<sup>2</sup> 10<sup>3</sup> 10<sup>4</sup> 10<sup>5</sup>

Frequency (Hz)

10-3 10-2 10-1 10<sup>0</sup> 10<sup>1</sup> 10<sup>2</sup> 10<sup>3</sup> 10<sup>4</sup> 10<sup>5</sup>

Frequency (Hz)

Fig. 29. EIS data of three spraycoated Y2O3 on anodized aluminum in 3.5wt% NaCl solution for 7 days. Excellent coating quality control is observed through the EIS study [28, 78].

Parameters Sample 1 Sample 2 Sample 3 Rs (ohm) 2.0 2.0 2.0 Rc (ohm) 40 40 40 Rp (ohm) 1.2x105 1.1x105 1.2x105 Rb (ohm) 5.0x107 5.0x107 5.1x107 K (ohm) 8.0x104 6.6x104 7.5x104 A (area in cm2) 20.0 20.0 20.0 Zc (ohm-cm2) 800 800 800 Zpo (ohm-cm2) 4.0x106 3.5x106 3.9x106 Zb (ohm-cm2) 1.0x109 1.0x109 1.0x109 Table 7. Interface parameters of three spraycoated Y2O3 on anodized aluminum

below (Table 7).




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