CHEM02200704003 Nilamadhab Pandhy - Homi Bhabha National ...
CHEM02200704003 Nilamadhab Pandhy - Homi Bhabha National ...
CHEM02200704003 Nilamadhab Pandhy - Homi Bhabha National ...
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
Chapter 7<br />
observed with increase in immersion time, instead surface became stained with degraded<br />
passive film and corrosion products with increase in root mean square roughness from 15 nm<br />
in as polished condition to 52 nm after immersion for 27 h.<br />
2. Potentiodynamic polarization study in 0.1 M, 0.5 M, 0.6 M, and 1 M nitric acid showed<br />
increase in passive current density and corrosion current density, and decrease in transpasive<br />
potential with increase in concentration of nitric acid. Passive current density increased by one<br />
order, corrosion current density increased by two order, and transpassive potential decreased<br />
by 150 mV vs. Ag/AgCl from 0.1 M to 1 M nitric acid.<br />
3. In-situ passive film surface morphology study in 0.1 M, 0.5 M, 0.6 M, and 1 M nitric acid<br />
using EC-AFM showed the growth of passive film in the form of platelet like structure at<br />
lower concentration of 0.1 M and 0.5 M nitric acid. At concentration of 0.6 M and 1 M nitric<br />
acid the platelet like structures got agglomerated, homogenized and started depleting from the<br />
surface leading to selective dissolution and opening up of oxide boundaries.<br />
4. X-ray photoelectron spectroscopy analysis of passive film as observed in in-situ study in 0.1<br />
M, 0.5 M, 0.6 M, and 1 M nitric acid revealed the presence of hydroxide and oxide layer on<br />
304L SS at lower concentration of 0.1 M and 0. 5 M nitric acid. Towards higher<br />
concentrations of 0.6 M and 1 M nitric acid, presence of oxide layer was observed. Overall, the<br />
passive film at lower concentration consists of hydroxide and oxide layer, and at higher<br />
concentration it consists of oxide layer only.<br />
7.2 Conclusions from the study on corrosion behaviour of nitrogen ion implanted AISI<br />
304L stainless steel in nitric acid medium<br />
Followings are the major conclusions from the study on “corrosion behaviour of nitrogen<br />
ion implanted AISI 304L stainless steel in nitric acid medium” to understand the effect of subsurface<br />
modification on the corrosion behaviour of 304L SS in nitric acid medium.