US EPA

1566119 

Journal Article 

Corrosion Behavior of Type 304L Stainless Steels in Nitric Acid Containing Free and Complexed Fluoride 

Sathe, S; Kain, V; Chandra, K 

2012 

Yes 

Corrosion
ISSN: 0010-9312 

68 

2 

10.5006/1.3683230 

WOS:000299539600009 

The corrosion behavior of Type 304L (UNS S30403) nitric
acid grade (NAG) stainless steel in boiling 9 M and 1 M nitric acid (HNO3) and with the addition
of 0.03 M sodium fluoride (NaF) and with fluoride complexed with 0.06 M to 0.15 M aluminum
nitrate (Al[NO3](3)) and 0.015 to 0.0375 M zirconium nitrate (Zr[NO3](4)) has been established.
The corrosion behavior has also been studied using potentiodynamic polarization in the same
environments at room temperature and at near boiling temperature and correlated to the measured
corrosion rates. It was shown that the fluoride addition accelerates anodic dissolution. The
surface film formed on stainless steel was analyzed using x-ray photoelectron spectroscopy to
show that fluorides do not remain attached to the surface. The effect of different ratios of
complexing with Al(NO3)(3) and Zr(NO3)(4) has been studied, showing more effectiveness of
zirconium. The corrosion behavior of Types 304L, 304L (welded), 310L (UNS S31000) stainless
steels and Alloy 690 (UNS N06690) was established in boiling HNO3 and HNO3 with complexed
fluoride and in its vapor and condensate phases. The corrosion rates were shown to be higher in
the vapor phase than in the concentrate phase for all the materials tested. The differences in
the corrosion rates measured in 48 h or 120 h exposures have been explained. 

corrosion rate; corrosion resistance; fluorides; nitric acid; polarization; temperature; vapor phase