CHEM02200704003 Nilamadhab Pandhy - Homi Bhabha National ...

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Chapter 7 1. Surface morphology examination of the nitrogen ion implanted 304L SS by AFM revealed smoothening of the surface with increase in dose rate. The smoothening of the surface is due to preferential sputtering from the grain boundaries during the process of implantation. 2. SIMS analysis of the nitrogen ion implanted 304L SS specimens showed enrichment of nitrogen in the surface. With enrichment of nitrogen in the surface, the intensity profiles of the major alloying elements such as iron, chromium and nickel initially decreased, and subsequently attained steady state with increase in depth of sputtering. 3. GIXRD and XPS analysis of the nitrogen ion implanted 304L SS specimens showed preferential formation of chromium nitride at higher doses. The formation of chromium nitride (Cr 2 N) at higher doses is due to their low enthalpy of formation. 4. Electrochemical corrosion investigations of unimplanted and nitrogen implanted 304L SS in 1 M nitric acid revealed decrease in passive current density and corrosion current density, and improvement in transpassive potential. The corrosion current density decreased by two order of magnitude, passive current density by one order of magnitude, and marginal improvement in transpassive potential by 10 mV vs. Ag/AgCl, respectively. 5. Surface morphology analysis of the unimplanted and nitrogen ion implanted 304L SS in 1 M nitric acid using AFM after polarization study showed aggressive grain boundary dissolution in unimplanted specimens, and resistance to grain boundary attack with increase in dose rate of nitrogen ion implantation. The results of morphological study after polarization show that nitrogen ions are effective in resisting the intergranular corrosion of 304L SS in nitric acid medium. The causative factor for the resistance to surface dissolution at higher doses is because formation of chromium nitride which increases the ability for oxide layer formation, and enrichment of nitrogen which buffers the local pH and decreases dissolution at grain boundaries.
Chapter 7 7.3 Conclusions from the study on corrosion performance of Ti, TiO 2 and duplex Ti-TiO 2 coated AISI 304L stainless steel in nitric acid medium Following are the major conclusions from the study on “corrosion performance of Ti, TiO 2 , and duplex Ti-TiO 2 coated 304L stainless steel in nitric acid medium” to understand the effect of top surface modification on the corrosion behaviour of 304L SS in nitric acid medium. 1 Single Ti layer coating on 304L SS showed low capacitive and high resistive property at 1 M nitric acid showing good passive film stability. However, at 8 M nitric acid the coating capacitance increased and polarization resistance decreased indicating formation of less stable passive film. The low stability of oxide film at higher concentration is due to high dissolution rate of the oxide film developed on the surface. 2 Single Ti layer coated 304L SS specimens showed moderate to marginal improvement in corrosion resistance in 1 M and 8 M nitric acid medium, respectively. The percentage of protection efficiency was 52 % in 1 M nitric acid, and 27 % in 8 M nitric acid. 3 Titanium dioxide (TiO 2 ) coated 304L SS showed low capacitive and high resistive property as compared to Ti coated 304L SS in both 1 M and 8 M nitric acid. 4 The improvement in corrosion resistance of TiO 2 coated 304L SS in both 1 M and 8 M nitric acid was better than Ti coated 304L SS despite presence of pores and other structural heterogeneities. However, at 8 M nitric acid uniform dissolution of the coated surface was observed. The protection efficiency was 95 % in 1 M and 43 % in 8 M nitric acid, respectively. 5 Duplex Ti-TiO 2 coated 304L SS showed reduction in the frequency of pore formation and their size as compared to single layer Ti and TiO 2 coatings. This shows the effectiveness of interlayer coating in minimization of heterogeneities, and controlling the microstructure.
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2.3 Effect of alloying elements on
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6.2.3.2 Open circuit potential vs.
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The ex-situ study of passive film w
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Fig.3.10: Schematic of electrical e
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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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C H A P T E R5
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Chapter 5 elements, and often impar
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Chapter 5 5.2 Results and discussi
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Chapter 5 Presence of oxygen is due
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Chapter 5 was an increase in marten
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Chapter 5 formation of Cr 2 N was a
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Chapter 5 electrochemical environme
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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
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Page 138 and 139: Chapter 6 particles range from 8×1
Page 140 and 141: Chapter 6 Results revealed that in
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
Page 162 and 163: Chapter 6 As compared to uncoated s
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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 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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