CHEM02200704003 Nilamadhab Pandhy - Homi Bhabha National ...

Chapter 6
Fig. 6.10d: Log f vs. Log |Z| for uncoated and TiO 2 coated 304L SS in 8 M HNO 3 [22].
Conc.
Substrate
condition
R s
cm 2 CPE 2
R ct2
cm 2 CPE 1
R ct1
cm 2
C dl2
-1 cm -2 S n
n
(0-1)
C dl1
-1 cm -2 S n
n
(0-1)
1 M Uncoated 2 6.5×10 -5 0.76 9.35×10 2 - - -
1 M TiO 2 coated 8 2.5×10 -5 0.89 3.47×10 4 1.3×10 -7 0.96 6×10 2
8 M Uncoated 1 5.8×10 -4 0.65 1.8×10 2 - - -
8 M TiO 2 coated 10 3.6×10 -5 0.72 5×10 2 1.8×10 -5 0.78 3.2×10 1
Table. 6.3: EIS fitted values for uncoated and TiO 2 coated 304L SS in 1 M and 8 M HNO 3 [22].
From the circuit parameters in Table. 6.3, it is clear that both coating capacitance (C dl1 ),
and coating resistance (R ct1 ) of TiO 2 coated 304L SS specimens showed good coating capacitance
as well as higher pore resistance in both the test solutions compared to uncoated, and Ti coated
specimens. The double layer capacitance (C dl2 ) and polarization resistance (R ct2 ) of TiO 2 coated
304L SS specimens also showed lower retained charge capacity, and high polarization resistance