HAL Id: cea-02506808
https://hal-cea.archives-ouvertes.fr/cea-02506808 Submitted on 12 Mar 2020
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Investigation of a single pit generated with a flow microcell
S. Heurtault, R. Robin, F. Rouillard, V. Vivier
To cite this version:
S. Heurtault, R. Robin, F. Rouillard, V. Vivier. Investigation of a single pit generated with a flow microcell. EMCR-2015 - 11th International Symposium on Electrochemical Methods in Corrosion Research, May 2015, Troia, Portugal. �cea-02506808�
INVESTIGATION OF A SINGLE PIT
GENERATED WITH A FLOW MICROCELL
Stéphane Heurtault, Raphaël Robin, Fabien Rouillard, Vincent Vivier
LISE-‐CNRS-‐UMR 8235, Université Pierre et Marie Curie, Paris, France
LECNA – CEA, DEN, DPC, SCCME, Gif-‐sur-‐YveMe, France
-0.0002 0 0.0002 0.0004 0.0006 0.0008 0.001 -0.8 -0.6 -0.4 -0.2 0 0.2 E vs MSE / V I / A 1 mV /s
In
tr
od
u
c)
on
316L stainless steel 0.5 M H2SO4 + 0.6 M NaCl
-‐ Lead-‐in-‐pencil technique
E.D. Parsons and al., J. Phys. Chem. 45 (1941) 1339
-‐ Single pit with SECM-‐like techniques
Wipf et al. (SECM – trichloroacetate reduc_on) Fushimi and Seo (Ion gun – Ag/AgCl)
Portail et al. (Ion gun – Ag/AgCl + EQCM)
-‐ Pit propaga_on for long _me
Lead-‐in pencil techniqueFlow microcell
How can we generate a single pit ?
Stainless steel in a chloride environment
!
Ex
p
er
ime
n
ta
l s
et
u
p
ΦExt : 500 mm Φint : 35 µm Fow-‐rate: 0.5 to 1000 μL/h
Flow microcell descrip_on
Ex
p
er
ime
n
ta
l s
et
u
p
Capillary posi_oning
N. Aouina, F. Balbauld-‐Célérier, F. Huet, S. Joiret, H. Perrot, F. Rouillard, V. Vivier, Corr. Sci., 62 (2012) 1-‐4.
Measure of the electrolyte resistance varia_on due to the presence of the
capillary in the close vicinity of the stainless steel electrode
Pit ini_a_on and propaga_on
Release of chloride ion with a capillary (controlled flow rate) – measure of current (or poten_al) as a func_on of
_me
propaga_on
phase 1 propaga_on phase 2 induc_on
Re
p
ro
d
u
ci
b
ili
ty
7 iden_cal experiments performed in 0.5 mol/L H2SO4 at 20°C Flow rate : 5.4 μL/h [Cl-‐] = 3 mol/L E316L = 0 V/MSE 0 10 20 30 40 50 60 0,0 0,5 1,0 1,5 2,0 2,5
I
316L/ m
A
Time / min
!In
flu
en
ce of t
h
e elect
rod
e p
ot
en
)
al
-0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 -100 -50 0 50 100 150 200 I 316L ( µ A ) E 316L (V/MSE) 0 1 2 3 4 5 0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 I 31 6 L / m A Time / h SE M ob se rv a_ on s ao er 1 h ou rE/I curve in 0.5 mol/L H2SO4 solu_on
In
flu
en
ce of t
h
e elect
rod
e p
ot
en
)
al
0 10 20 30 40 50 60 0 1 2 3 4 5 6 0.3 V/MSE 0.5 V/MSE 0.4 V/MSE 0.2 V/MSE 0.1 V/MSE 0 V/MSE -0.2 V/MSE I 316L / m A Time / min -0.4 V/MSE 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0 1 2 3 4 0 V/MSE I 316L / m A Time / h 0.4 V/MSE 0.0 0.5 1.0 1.5 2.0 0 1 2 3 4 0.4 V/MSE I 316L / m A Time / h 0 V/MSE Experiments performed in 0.5 M H2SO4 at 20°CFlow rate : 5.4 μL/h [Cl-‐] = 3 M
The current increases with poten_al
In
flu
en
ce of t
h
e flo
w r
at
e
Experiments performed in 0.5 M H2SO4 at 20°C [Cl-‐] = 3 M
The “steady-‐state” current increases with the flow rate The induc_on _me decreases with the flow rate
Same evolu_on when varying the Cl-‐ concentra_on
0 10 20 30 40 50 60 70 0 1 2 3 4 5 I 316L / m A Temps / min 0 10 20 30 40 50 60 0 1 2 3 4 5 6 0.3 V/MSE 0.5 V/MSE 0.4 V/MSE 0.2 V/MSE 0.1 V/MSE 0 V/MSE -0.2 V/MSE I 316L / m A Time / min -0.4 V/MSE
SEM observa_ons of a single pit generated on 316L steel aoer 1 hour of propaga_on
In
flu
en
ce of t
h
e flo
w r
at
e
Experiments performed in 0.5 M H2SO4 at 20°C [Cl-‐] = 3 M 0 1 2 3 4 5 6 7 8 0.0 0.5 1.0 1.5 2.0 I 316L / mA Temps / h 6 4.2 3 1,8 1,2 0,6 0 Débit Cl- / µL.h-1
It’s possible to control the rate of the pitng by changing the flow rate
à
it’s a way to see the influence of the amount of chloride concentra_on
varia_on on the pitng evolu_on
à
pit can restart aoer passiva_on
In
flu
en
ce of t
h
e ch
lorid
e c
on
cen
tr
a)
on
Experiments performed in 0.5 M H2SO4 at 20°C [Cl-‐] = 1.2 M
20 iden_cal experiments performed as a func_on of _me
0 2 4 6 8 10 12 14 0.0 0.5 1.0 1.5 2.0 2.5 I 316L / m A Time / h
3h
11h30
For lower chloride concentra_on (<1.5 mol/L ) forma_on of a pit with a cover whereas for higher concentra_on, an open pit was always obtained
Ev
o
lu
)
o
n
o
f
th
e
p
it
d
ime
n
si
o
n
Experiments performed in 0.5 M H2SO4 at 20°C with [Cl-‐] = 3 M
Depth and diameter were obtained from op_cal observa_ons: aoer 1 h, the mean radius increases with poten_al whereas the depth remains constant (about 180 μm)
-0.4 -0.2 0.0 0.2 0.4 300 450 600 750 900 1050 1200 R ad ius (µ m ) E 316L (V/MSE) 50 100 150 200 250 300 D ep th (µ m ) Aoer 1 h
0,25 0,50 0,75 1,00 1,25 1,50 1,75 2,00 500 600 700 800 900 1000 Ra di u s / µm
Flow Rate * [Cl-] / mmol.min-1
150 200 250 300 350 De pt h / µm
Ev
o
lu
)
o
n
o
f
th
e
p
it
d
ime
n
si
o
n
Flow rate and concentra_on play the same role on pit propaga_on
Depth and diameter were obtained from op_cal observa_ons: aoer 2 h, the mean radius increases with poten_al whereas the depth remains constant (about 270 μm)
Ev
o
lu
)
o
n
o
f
th
e
p
it
d
ime
n
si
o
n
0 1 2 3 4 5 0 100 200 300 400
With pit cover
0 V/MSE 0 V/MSE 0.2 V/MSE 0.4 V/MSE t < 1h : 0 V/MSE t > 1h : 0.4 V/MSE Mean depth D ep th / µ m Time / h Applied potential
Without pit cover
Influence of both the dura_on and poten_al: each point
corresponds to one experiment
Ev
o
lu
)
o
n
o
f
th
e
p
it
d
ime
n
si
o
n
Influence of both the dura_on and poten_al: each point
corresponds to one experiment
Change in poten_al modify the pit radius
0 1 2 3 4 5 0 200 400 600 800 1000 1200 1400 Applied potential 0 V/MSE 0.4 V/MSE t < 1h : 0 V/MSE t > 1h : 0.4 V/MSE Ra di us / µm Time / h
Ev
o
lu
)
o
n
o
f
th
e
p
it
d
ime
n
si
o
n
0 1 2 3 4 5 6 7 8 9 10 100 200 300 400 500 600 1.2 M NaCl 3 M NaCl D ep th / µ m Time / h Cl- microcapillary concentration 0 1 2 3 4 5 6 7 8 9 10 0 200 400 600 800 1000 1200 3 M NaCl 1.2 M NaCl Cl- microcapillary concentration R ad ius / µ m Time / h
For 3 M NaCl solu_on
p
= 126 +1.57 i t − 2700
0.54
for t > 45 min
r
= 250 + 26.36 i t −180
0.34for t > 3 min
p
= 111+1.93i t − 2700
0.53for t > 45 min
r
= 130 + 4.20 i t −180
0.53for t > 3 min
For 1.2 M NaCl solu_on
Fitng of the experimental results
Ev
o
lu
)
o
n
o
f
th
e
p
it
d
ime
n
si
o
n
Analysis of the radius and depth evolu_ons
OpDcal measurement of pit
parameters
fit
Time deriva_ve
Law p=f(t)
Law dp/dt=g(t)
current
J = ρnF/M dp/dt
bulk
316L SS
j
wallj
boMomWe can dis_nguish two contribu_on
for the current density
Ev
o
lu
)
o
n
o
f
th
e
p
it
d
ime
n
si
o
n
0 1 2 3 4 5 0 100 200 300 0 V/MSE 0.4 V/MSE t < 1h : 0 V/MSE t > 1h : 0.4 V/MSE Applied potential J pi t w al ls / m A .cm -2 Time / h 0 1 2 3 4 5 0 50 100 150 200 J pi t bot tom / m A .cm -2 Time / h 0 V/MSE 0.4 V/MSE t < 1 h : 0V/MSE t > 1 h : 0.4 V/MSE Applied potential
Change in poten_al (1h) does not modifies the current density on the pit boMom
Evolu_on of the pit depth as √t
à Diffusion control of pit propaga_on along the z-‐direc_on
Change in poten_al (1h) modifies the current density on the pit wall
à Ohmic control of the pit
propaga_on along the radial direc_on
pit wall
Pr
o
pag
a)o
n /
re
p
as
si
va
)
o
n
Chronoamperometry experiments: the microcapillary was removed aoer 2 hours or 3 hours and the solu_on bulk was
changed.
Con
cl
u
si
on
s
-‐ P
OSSIBILITYTO
GENERATE
A
SINGLE
PIT
AT
A
GIVEN
LOCATION
AND
TO
SUSTAIN
ITS
PROPAGATION
FOR
LONG
TIME
-‐ E
VOLUTIONOF
THE
PIT
DIMENSIONS
AS
A
FUNCTION
OF
DIFFERENT
PARAMETERS
(
CHLORIDECONCENTRATION
,
ELECTRODEPOTENTIAL
,
TIME…)
-‐ 2
DIFFERENTRATES
OF
PIT
PROPAGATION
WERE
EVIDENCED
: 1
FORPIT
BOTTOM
AND
1
FORPIT
WALL
