Ellingham Diagram application.pdf
of 7
-
Upload
jon-castillo -
Category
Documents
-
view
63 -
download
0
Transcript of Ellingham Diagram application.pdf
-
oxide formula,normalized to 1 mol O2
example R ox O2
2 R2O = R4O2 Na2O 4 2 1
2 RO = R2O2 CaO 2 2 1
2/3 R2O3 = R4/3O2 Al2O3 4/3 2/3 1
1 RO2 = R1O2 SiO2 1 1 1
2/5 R2O5 = R4/5O2 P2O5 4/5 2/5 1
1/2 R3O4 = R3/2O2 Fe3O4 3/2 1/2 1
2/3 RO3 = R2/3O2 WO3 2/3 2/3 1
OxideORG
OxideR +
2
-
Principle of Richardson-
Ellingham diagram:
abscissa starts with
absolute 0 K
ordinate represents
Gibbs energie of oxidation
reactions for a turnover
of 1 mol O2
the O2 partial pressure is fixed
by O2 concentration directly,
or by pivot equilibria:
H2/H2O,
CO/CO2,
H2/H2S, etc.
-
0 300 600 900 1200-1200
-1100
-1000
-900
-800
-700
-600
-500
-400
-300
-200
-100
0
4/3 Al + O
2 = 2/3 A
l2O3
Si + O2 =
SiO2
2 H2 + O2 = 2 H2O
2 CO + O2 = 2 CO2
6 FeO + O
2 = 2 F
e3O4
4 Fe3O
4 + O2
= 6 Fe
2O3
G in kJ per mol O2
C
-28
-24
-20
-16
-12
-8
-4
0
12
10
8
6
4
2
0
-2
12
10
8
6
4
2
0
-2
-4
log [CO]/CO2]
log [H2]/[H
2O] log [O
2]
-
0 300 600 900 1200-800
-700
-600
-500
-400
-300
-200
-100
0
G in kJ per mol O2
C
Ag2O
0
VOV2O3
Cr2O3
VO2
ZnO
V2O5
FeO
Fe3O4
Fe2O3
CoONiO
PbOCrO
3
Cu2O
Pb3O4
CuO
log [CO]/CO2]
-3
-2
7
6
5
4
3
2
1
0
-1
log [H2]/[H
2O]
-4
-3
-2
-1
7
6
5
4
3
2
1
0
log [O2]
-20
-18
-16
-14
-12
-8
-6
-4
-2
-10
-
0 300 600 900 1200-800
-700
-600
-500
-400
-300
-200
-100
0
G in kJ per mol O2
C
Ag2O
0
VOV2O3
Cr2O3
VO2
ZnO
V2O5
FeO
Fe3O4
Fe2O3
CoONiO
PbOCrO
3
Cu2O
Pb3O4
CuO
log [CO]/CO2]
-3
-2
7
6
5
4
3
2
1
0
-1
log [H2]/[H
2O]
-4
-3
-2
-1
7
6
5
4
3
2
1
0
log [O2]
-20
-18
-16
-14
-12
-8
-6
-4
-2
-10
G in kJ per mol O2
C
log [CO] / CO2]
log [H2] / [H2O] log [ O2]
0
-400
4 eV
-10
-8
-6
-4
-2
0
-10
-5
0
l
o
g
a
(
o
x
i
d
e
)
600 C 1200 C
shift for GMIX = RT ln a(oxide)
-
0 300 600 900 1200-1200
-1100
-1000
-900
-800
-700
-600
-500
-400
-300
-200
-100
0
4/3 Al + O
2 = 2/3 A
l2O3
Si + O2 =
SiO2
2 H2 + O2 = 2 H2O
2 CO + O2 = 2 CO2
6 FeO + O
2 = 2 F
e3O4
4 Fe3O
4 + O2
= 6 Fe
2O3
G in kJ per mol O2
C
-28
-24
-20
-16
-12
-8
-4
0
12
10
8
6
4
2
0
-2
12
10
8
6
4
2
0
-2
-4
log [CO]/CO2]
log [H2]/[H
2O] log [O
2]
40 m
Sperical Si-Fe particle in a
glass generated at 1400 C
by to the reactions:
2FeOAl2FeOAl
SiOAl SiOAl
3232
34
3232
234
++
++
600
900
1200
1500
C
Fe Siwt. %
liquid
1214
953
Silow-
FeSi2FeSi
Fe2Si
bcc
fcc high-
FeSi2
Fe4Si3
-
0 300 600 900 1200-1200
-1100
-1000
-900
-800
-700
-600
-500
-400
-300
-200
-100
0
4/3 Cr + O
2 = 2/3 C
r2O3
4/3 Al + O
2 = 2/3 A
l2O3
Si + O2
= SiO2
2 H2 + O2 = 2 H2O
2 CO + O2 = 2 CO2
6 FeO + O
2 = 2 F
e3O4
4 Fe3O
4 + O2
= 6 Fe
2O3
G in kJ per mol O2
C
-28
-24
-20
-16
-12
-8
-4
0
12
10
8
6
4
2
0
-2
12
10
8
6
4
2
0
-2
-4
log [CO]/CO2]
log [H2]/[H
2O] log [O
2]
oxide scales on steel:
Al2O3
Cr2O3
SiO2
steel
