CHEMICAL TREATMENT FIGURE 1
organic nitrogen materials were intro- duced to make simulated water with dif- ferent concentrations of TN. (NH4 KNO2
)2 , H2 NCSNH2 , and KNO3 SO4 , were
added separately into the clean water to make solutions with concentrations of 0.2, 2.0, and 20 mg/L. CS used in the experiments consisted of the following elements: 0.16% C, 0.24% Si, 0.45% Mn, 0.035% S, ≤
8 IVL !! .M XMZ\]ZJI\QWV †
Trade name. FIGURE 2
signal at the corro- sion potential. To test the reliability and reproducibility of the measurements, duplicate experi- ments were per- formed in each case. The corrosion morphology of CS was investigated using I ÅMTL MUQ[[QWV [KIV- ning electron micro- scope (Quanta 200†
). Results
.QO]ZM [PW_[ \PM MNNMK\ WN <6 KWV- centrations on the corrosion of CS, which was investigated by electrochemical measurement. As the concentration of TN increased, the corrosion current (icorr
and the corrosion potential became more negative; (2) in KNO2
and KNO3 NCSNH2 solu-
tions, anodic reactions were restrained; and (3) in H2
)
of CS decreased. .QO]ZM I [PW_[ XW\MV\QWLaVIUQK
XWTIZQbI\QWV K]Z^M[ IVL .QO]ZM J [PW_[ the icorr
of CS in typical nitrogenous solu-
tions. As compared with the control, there were some changes in the corrosion potentials and the cathodic and anodic slopes of CS samples: (1) in (NH4
)2 SO4 J QVLQKI\M \PI\ \PM VQ\ZWOMVW][ )2 SO4 solutions, both
anodic and cathodic reactions were re- strained. Corrosion currents shown in .QO]ZM
solutions had inhibiting effects, except for (NH4
, which increased corro-
sion of CS. In the presence of a constant [WT]\QWV KWVKMV\ZI\QWV \PM MNÅKQMVKa WN corrosion inhibition decreased in this order: H2
NCSNH2 > KNO3 > KNO2 . Nyquist plots of electrodes immersed solutions, the anodic reaction accelerated for 30 min in solutions with various
Effect of TN concentrations on the corrosion of CS.
Effects of typical nitrogenous compounds on the corrosion of CS. NACE International, Vol. 51, No. 11
November 2012 MATERIALS PERFORMANCE 55