CHEM02200704003 Nilamadhab Pandhy - Homi Bhabha National ...

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Chapter 6 As compared to uncoated specimens, morphology of TiO 2 coated specimens after polarization did not reveal any grain boundary opening up, thereby showing greater resistance to surface dissolution as well as intergranular corrosion (Fig. 6.12b and d) [22]. The improved resistance to intergranular corrosion is due to high passive film stability as well as low anodic dissolution rate of titanium dioxide in nitric acid medium. The morphology of TiO 2 coated specimens after polarization in 1 M nitric acid did not show much change in surface morphology (Fig. 6.12b). However, in 8 M nitric acid uniform dissolution of the coated surface was observed (Fig. 6.12d), leading to change in shape, and decrease in particle size of the oxide layer [22]. Moreover, the pinholes were widely open, and apparent separation between the particles were well observed. This is due to shrinkage in size of the particles as a result of dissolution along the periphery at the inter-columnar boundaries in the coated surface [22]. Nevertheless, in both concentrations, the extent of dissolution was less as compared to uncoated specimens, and no intergranular corrosion was observed [22]. 6.2.3 Corrosion behaviour of duplex Ti-TiO 2 coated 304L SS in nitric acid medium 6.2.3.1 Phase and morphology characterization The phase analysis of the duplex Ti-TiO 2 coated 304L SS revealed anatase phase as shown for TiO 2 coated 304L SS (Fig. 6.7). The morphological analysis of the duplex Ti-TiO 2 coated specimen is shown in Fig. 6.13a-d. The morphology of the coated surface showed spherical particles uniformly covering the surface (Fig. 6.13a). The histogram showing the distribution of the particles as a function of frequency of formation is shown in Fig. 6.13b. The sizes of the particles generally range from 12×10 -3 µm 2 to 1.25 µm 2 . However, certain agglomerated particles were having sizes up to 4.5 µm 2 . The exact location, and morphology of the pores present on the surface is shown in Fig. 6.13c. The histogram showing the distribution of the size of the pores as a function of frequency of formation is shown in Fig. 6.13d. The size of the pores in the duplex Ti-
Chapter 6 TiO 2 coated specimens ranges from 4×10 -3 µm 2 to 90×10 -3 µm 2 . It is clear from Fig. 6.2d. 6.8d, and 6.13d that the size of the pores as well as the extent of formation was decreased from single layer Ti and TiO 2 coating to duplex Ti-TiO 2 coating. The prior deposition of Ti coating facilitates the nucleation and growth of TiO 2 particles at defective sites, and lead to uniform coverage of the surface which is desirable from corrosion point of view [206]. Nevertheless, pores can also be noticed in the duplex coated surface which could be due to the parallel overlap of pores in Ti, and thereafter in TiO 2 coating. The root mean square roughness (R q ) on the surface was 16 nm. Fig. 6.13a-d: (a) Morphology of duplex Ti-TiO 2 coated 304L SS, (b) histogram for the particle size distribution, (c) morphology of the pores, and (d) histogram for the size distribution of the pores.
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Fig.6.11: Polarization study of unc
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AISI: American Institute of Steel I
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Chapter 1 C H A P T E R 1 Spent Nuc
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Chapter 1 1.3 Challenges in spent n
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Chapter 1 corrosion resistance. The
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Chapter 1 choice of zirconium is du
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C H A P T E R2
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Chapter 2 temperature, (c) higher i
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Chapter 2 Chromium in excess of 12
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Chapter 2 2. 3 Effect of alloying e
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Chapter 2 The twins are identified
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Chapter 2 and at temperature around
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Chapter 2 of adsorption of oxygen o
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Chapter 2 transpassive dissolution
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Chapter 2 healing chromium oxide fi
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Chapter 2 their segregation to the
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Chapter 2 is intimately related to
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Chapter 2 in nature because the dis
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C H A P T E R3
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Chapter 3 3.1.1.2 Specimen preparat
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Chapter 3 ionized. However, differe
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Chapter 3 various industrial applic
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Chapter 3 In the present investigat
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Chapter 3 3.1.3.2 Atomic force micr
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Chapter 3 present on the surface fo
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Chapter 3 necessary condition is th
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Chapter 3 Y m is the sputter yield.
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Chapter 3 Fig. 3.7: Schematic of X-
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Chapter 3 rate of 10Å/min using 5
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Chapter 3 different doses of nitrog
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Chapter 3 The modulus of electroche
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Chapter 3 equivalent circuit as sho
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Chapter 3 reference electrode with
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Chapter 3 for understanding the pas
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C H A P T E R4
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Chapter 4 encountered by all materi
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Chapter 4 pitting, and intergranula
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Chapter 4 The ridged structure, and
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Chapter 4 nitric acid is that the b
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Chapter 4 Potential (V) Vs Ag/AgCl
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Chapter 4 4.2.3 In-situ electrochem
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Chapter 4 The surface morphologies
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Chapter 4 a b c d Opening up of gra
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Chapter 4 Intensity (Arbitrary unit
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Chapter 4 The chromium, and oxygen
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Chapter 4 Intensity (Arbitrary unit
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Page 114 and 115: Chapter 5 elements, and often impar
Page 116 and 117: Chapter 5 5.2 Results and discussi
Page 118 and 119: Chapter 5 Presence of oxygen is due
Page 120 and 121: Chapter 5 was an increase in marten
Page 122 and 123: Chapter 5 formation of Cr 2 N was a
Page 124 and 125: Chapter 5 electrochemical environme
Page 126 and 127: Chapter 5 N + Dose E corr (mV vs. A
Page 128 and 129: Chapter 5 layer capacitance (C dl )
Page 130 and 131: Chapter 5 correlation between surfa
Page 132 and 133: Chapter 5 boundary dissolution was
Page 134 and 135: Chapter 6 C H A P T E R 6
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Page 138 and 139: Chapter 6 particles range from 8×1
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Page 142 and 143: Chapter 6 The change over from capa
Page 144 and 145: Chapter 6 The impedance parameters
Page 146 and 147: Chapter 6 Conc. Substrate condition
Page 148 and 149: Chapter 6 6.6a-d. The uncoated spec
Page 150 and 151: Chapter 6 (55.18°) respectively, w
Page 152 and 153: Chapter 6 OCP shifted in noble dire
Page 154 and 155: Chapter 6 The high phase angle over
Page 156 and 157: Chapter 6 Fig. 6.10d: Log f vs. Log
Page 158 and 159: Chapter 6 Fig. 6.11b: Polarization
Page 160 and 161: Chapter 6 Covalent aspect of lattic
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Page 166 and 167: Chapter 6 Similarly, the plots for
Page 168 and 169: Chapter 6 for the duplex coating, a
Page 170 and 171: Chapter 6 Fig.6.16b: Polarization s
Page 172 and 173: Chapter 6 6.2.3.5 Morphological exa
Page 174 and 175: Chapter 7 C H A P T E R 7 The cha
Page 176 and 177: Chapter 7 1. Surface morphology exa
Page 178 and 179: Chapter 7 6 Duplex Ti-TiO 2 coated
Page 180 and 181: Chapter 7 EC-SPM study on effect
Page 183 and 184: [1] Baldev Raj, U. Kamachi Mudali,
Page 185 and 186: [37] G. Okamoto, T. Shibata, Corros
Page 187 and 188: [79] M. Moens, M. Van Craen, F.C. A
Page 189 and 190: [117] R.E.Williford, C.F.Windisch J
Page 191 and 192: [157] N. Mottu, M. Vayer, R. Erre,
Page 193: [197] M. Metikos Hukovic, M. Ceraj
Page 196 and 197: [19] H. H. Uhlig, Corros Sci, 19 (1
Page 198 and 199: [57] J. F. Ziegler, J. P. Biersack,
Page 200 and 201: [97] I. Betova, M. Bojinov, V. Kara
Page 202 and 203: [139] V. Ashworth, R. P. M. Procter
Page 204 and 205: [176] G. Frankel, G. Grundmeier, H.
Page 207 and 208: List of publications 1. Referred
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CHEM02200704003 Nilamadhab Pandhy - Homi Bhabha National ...

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