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Ppt of kinetics of corrosion of chemical
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18
nF
Ita m
2
nF
ia
AnF
Ia
AtnF
Ita
At
m Laju. Korosi
i
dm s
mg r 2
( mills (0.001 inc) per year )
nD
ia r 0 , 129
nFD
ia r
Laju reaksi ( i 0 ) pada reaksi pelepasan hidrogen
2H+^ + 2e-^ H 2
Sangat bergantung pada banyak faktor termasuk laju perpindahan
elektron dari logam ke ion hidrogen. Jenis logam berpengaruh
pada laju transfer elektron
Metal log i 0 (A/cm^2 )
Pb, Hg –
Zn –
Sn, Al, Be –
Ni, Ag, Cu, Cd –
Fe, Au, Mo –
W, Co, Ta –
Pd, Rh –
Pt –
r r r RT
nF
nF
0
ir is anodic or cathodic current
β is the charge transfer barrier coefficient , ±0.
n is the number of participating electrons
R is the gas constant, 8.314 J mol−1^ K−
T is absolute temperature (K)
F is 96,485 C/(mol of electrons)
r r r RT
nF
nF
0
KATODIK ANODIC
Jika η katodik, maka bagian ANODIC ≈ 0
Jadi,
r r RT
nF
0
0
log 10 i
i b
c c c
0
b log i b log i c c r c
0
log
i
nF c
log 0
log
i nF
i nF
c r
0
log 10
i
i b
c c c
Log i (A/m^2 )
Overpotensial
η
(V)
Log i 0
E^0
KATODIK
ANODIK
x
jO D
0 0
bulk c L
i i nFD 0
L
conc i
i
nF
log 1
kehilangan 25 mg selama 12 jam.
a. berapa arus yang mengalir karena korosi?
b. Jika luas spesimen 200 cm^2 berapa laju korosi dalam
satuan mg/dm^2 .hari?
c. Berapa laju korosi dalam mpy? dan μm/yr]m/yr?
Jawab:
a. Massa atom Zn=65.
b. Laju korosi
c. Laju Korosi (mpy)
densitas Zn = 7.13 g/dm^3
nF
Ita m ta
mnF I
A t
m
Luas Waktu
massa r
..
nD
ia r 0 , 129