sulfur and moisture effects on alumina scale and tbc ... · sulfur and moisture effects on alumina...
TRANSCRIPT
Sulfur and Moisture Effects on Alumina Scale and TBC Spallation
James L Smialek NASA Glenn Research Center, Cleveland, OH 44135 Presented at GE Aviation, Evendale, OH May 9, 2007
It has been well established that a few ppmw sulfur impurity may segregate to the interface of thermally grown alumina scales and the underlying substrate, resulting in bond degradation and premature spallation. This has been shown for NiAl and NiCrAl-based alloys, bare single crystal superalloys, or coated superalloys. The role of reactive elements (especially Y) has been to getter the sulfur in the bulk and preclude interfacial segregation. Pt additions are also very beneficial, however a similar thermodynamic explanation does not apply. The purpose of the present discussion is to highlight some observations of these effects on Rene′142, Rene′N5, PWA1480, and PWA1484. For PWA1480, we have mapped cyclic oxidation and spallation in terms of potential sulfur interfacial layers and found that a cumulative amount of about one monolayer is sufficient to degrade long term adhesion. Depending on substrate thickness, optimum performance occurs if sulfur is reduced below about 0.2-0.5 ppmw. This is accomplished in the laboratory by hydrogen annealing or commercially by melt-fluxing. Excellent 1150°C cyclic oxidation is thus demonstrated for desulfurized Rene′142, Rene′N5, and PWA1484. Alternatively, a series of N5 alloys provided by GE-AE have shown that as little as 15 ppmw of Y dopant was effective in providing remarkable scale adhesion. In support of a Y-S gettering mechanism, hydrogen annealing was unable to desulfurize these alloys from their initial level of 5 ppmw S. This impurity and critical doping level corresponds closely to YS or Y2S3 stoichiometry. In many cases, Y-doped alloys or alloys with marginal sulfur levels exhibit an oxidative sensitivity to the ambient humidity called Moisture-Induced Delayed Spallation (MIDS). After substantial scale growth, coupled with damage from repeated cycling, cold samples may spall after a period of time, breathing on them, or immersing them in water. While stress corrosion arguments may apply, we propose that the underlying cause is related to a hydrogen embrittlement reaction: Alalloy + 3 H2O = Al(OH)3 + 3H+ + 3e-. This mechanism is derived from an analogous moisture-induced hydrogen embrittlement mechanism originally shown for Ni3Al and FeAl intermetallics. Consequently, a cathodic hydrogen charging technique was used to demonstrate that electrolytic de-scaling occurs for these otherwise adherent alumina scales formed on Y-doped Rene′N5, in support of hydrogen effects. Finally, some TBC observations are discussed in light of all of the above. Plasma sprayed 8YSZ coatings, produced on PWA1484 without a bond coat, were found to survive more than 1000 1-hr cycles at 1100°C when desulfurized to below 0.1 ppmw. At higher sulfur (1.2 ppmw) levels, moisture sensitivity and delayed TBC failure, referred to as ‘Desk Top Spallation,’ occurred at just 200 hr. Despite a large degree of scatter, a factor of 5 in life improvement is indicated for desulfurized samples in cyclic furnace tests, confirming the beneficial effect of low sulfur alloys on model TBC systems. (DTS and moisture effects are also observed on commercially applied PVD 7YSZ coatings on Rene′N5+Y with Pt-aluminide bond coats). These types of catastrophic failure were subverted on the model system by segmenting the substrate into a network of 0.010” high ribs, spaced ¼ in. apart, prior to plasma spraying. No failures occurred after 1000 cycles at 1150°C or after 2000 cycles at 1100°C, even after water immersion. The benefit is described in terms of elasticity models and a critical buckling stress.
https://ntrs.nasa.gov/search.jsp?R=20070022367 2019-03-14T11:10:47+00:00Z
1
Nat
iona
l Aer
onau
tics
and
Spac
e Ad
min
istra
tion
ww
w.n
asa.
gov
Sulfu
r and
Moi
stur
e Ef
fect
s on
Alu
min
a Sc
ale
and
TBC
Spa
llatio
n
Jam
es L
. Sm
iale
k
NA
SA
Gle
nn R
esea
rch
Cen
ter
Cle
vela
nd, O
H
GE
Avi
atio
nM
ay 9
, 200
7, E
vend
ale,
OH
2
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Ou
tlin
e of
Rev
iew
•O
verv
iew
of
com
positio
nal effects
•C
ritical sulfur
conte
nt
and Y
/S r
atio
•M
ois
ture
-induced d
ela
yed s
palla
tion;
•D
esk T
op S
palla
tion
•C
yclic
models
(C
OS
P f
or
Win
dow
s)
3
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Co
mp
osit
ion
s a
nd
Pre
vale
nt
Scale
Co
mp
on
en
ts(w
eig
ht
%)
allo
yC
oA
lC
rT
aW
Mo
Re
Ti
Hf
SY
pp
mw
pp
mw
PW
A 1
48
05
5.0
10
12
40
01
.50
.06
.70
.0
PW
A 1
48
41
05
.65
96
23
0.0
0.1
1.2
0.0
(Re
né
14
2)
13
6.2
66
61
33
.50
.02
.06
.10
.0
Re
né
N5
86
.27
75
23
0.0
0.2
3-6
0-1
00
Al 2
O3,
Ni(A
l,C
r)2O
4, C
rTaO
4,
NiT
a2O
6, H
fO2,
Cr 2
O3, N
iO, T
iO2
(pro
tective,
neutr
al,
detr
imenta
l)
4
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Oxid
ati
on
Issu
es f
or
Ni-
base S
up
era
llo
ys
•A
l 2O
3 p
rote
ctive s
cale
s; exte
rnal vs inte
rnal oxid
ation
•N
iAl 2
O4, N
iTa
2O
6,
CrT
aO
4 r
ela
tively
innocuous
•Layere
d:
a)
NiA
l 2O
4, N
iTa
2O
6 o
ute
r tr
ansie
nts
b)
Al 2
O3 inner
layer
•C
r 2O
3 (?),
NiC
r 2O
4,
NiO
, T
iO2, H
fO2 n
on-p
rote
ctive s
cale
•N
iMoO
4,
NiW
O4, C
rNbO
4,
V2O
5,
etc
. als
o d
etr
imenta
l
•C
o g
enera
lly a
cts
in c
oncert
with N
i
•S
(adhesio
n)
contr
ol:
a)
Y (
Hf, Z
r?)
and g
ettering
b)
or
desulfurization
5
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
SE
BS
E
Tra
nsi
ent
Sca
le a
nd
Alu
min
aH
igh
S 1
48
4,
12
00
oC
, 2
5 h
Air
/75
h A
r
6
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
All
oy
W/A
A
lC
rT
iT
aN
bM
oW
rati
o1/5
Cr+
Al
1T
AZ-8
A0.5
66.0
6.0
08
2.5
44
2.3
17.2
0
2TR
W-R
-0.9
65.3
8.0
0.8
60.3
34
1.3
56.9
0
3B
-1900
-1.4
06.0
8.0
14.3
0.1
60.1
1.4
17.6
0
4N
AS
A-T
RW
-VIA
-1.4
85.4
6.1
19
0.5
25.8
1.8
16.6
2
5B
-1900 +
Hf
-1.6
86.0
8.0
14.3
0.1
60.1
1.4
17.6
0
6M
AR
-M-2
47
-4.2
25.5
8.2
13
00.6
10
1.2
37.1
4
7IN
-713 L
C-6
.20
5.9
12.0
0.6
02
4.5
00.9
08.3
0
8P
W-1
480 S
C-7
.44
5.0
10.0
1.5
12
00
41.1
27.0
0
9TR
W-1
800
-8.6
56.0
13.0
0.6
01.5
09
0.8
58.6
0
10
Rene 1
25
-21.2
25.0
9.0
2.5
3.8
02
70.9
26.8
0
11
MA
R-M
-246
-24.4
45.0
11.0
1.5
20
00
0.8
17.2
0
12
Re
ne
120
-38.5
74.3
9.0
43.8
02
70.7
06.1
0
13
NX-1
88
-48.7
68.0
0.0
00
018
08.0
0
14
MA
R-M
-200
-53.5
95.0
9.0
20
10
12.5
0.8
66.8
0
15
U-7
00 C
ast
-55.2
14.3
15.0
3.5
00
4.5
00.4
47.3
0
16
MA
R-M
-421
-74.1
14.3
15.8
1.8
02
23.8
0.4
77.4
6
17
MA
R-M
-200+
Hf
-89.8
05.0
9.0
20
10
11.5
0.8
66.8
0
18
IN-7
92
-166.2
63.2
12.7
4.2
3.9
02
3.9
0.4
25.7
4
19
IN-1
00
-180.3
35.5
10.0
5.5
00
30
0.6
67.5
0
20
WA
Z-2
0-1
98.0
56.5
0.0
00
00
18.5
6.5
0
21
TA
Z-8
-213.9
76.0
6.0
08
04
42.3
17.2
0
22
IN-9
39
-227.6
02.0
22.0
3.6
1.5
10
20.1
76.4
0
23
IN-7
38
-232.4
53.4
16.0
3.4
1.7
50.9
1.7
52.6
0.3
66.6
0
24
MA
R-M
-211
-269.7
65.0
9.0
20
2.7
2.5
50.8
66.8
0
25
Re
ne
80
-330.3
53.0
14.0
50
04
00.3
05.8
0
1100
oC
, 200 h
rm
g/c
m2
avg
=7.0
4
std
ev=
0.6
9
Rankin
g D
iagra
m o
f 25 N
i S
upera
lloys
7
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Cr,
wt. %
05
10
15
20
Al, wt. %
02468
10
conventional S
A
fitted lin
e
Al
+ 0
.22
Cr
= 7
.25
r2 =
0.7
0
Invers
e C
orr
ela
tion o
f A
lum
inum
and C
hro
miu
m
in 2
5 S
upera
lloys
8
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
weig
ht %
allo
yin
g e
lem
ent
02
46
81
0
i hW/A /
-20
-100
Al
Ti
47.9
Nb
92.9
W
183.8
Pre
dic
ted
Cy
cli
c O
xid
ati
on
We
igh
t C
ha
ng
e
Ni-(6
Co
-6A
l-6
Cr-
6T
a)-
(1T
i-1
Nb
-1M
o-1
W)-
(0.2
Hf-
0.1
C)
Ta
Co
Mo
Ba
se
go
od
ba
d
9
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Dif
fusi
on
Co
ntr
oll
ed D
esu
lfu
riza
tio
n
•S a
tom
sS
dif
fus
ion
H2
H2S
?
oxid
e-f
ree s
urf
aceS
su
pera
llo
y c
ou
po
n
CS ~
DSt
/ L
2
10
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Eff
ect
of
Su
lfu
r C
on
ten
t o
n t
he
11
00
oC
Cyclic O
xid
ati
on
of
PW
A 1
480
ox
ida
tio
n t
ime
, 1
-hr
cy
cle
s
0100
200
300
400
500
weight c2
-15
-10-50
6.7
3.9
1.5
0.8
0.1
2
pp
mw
S
11
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
12
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
•P
WA
1480
–D
istinct
cri
tic
al
su
lfu
r c
on
ten
tand t
hic
kness e
ffect
– 0
.2 p
pm
w S
@ 1
mm
(40 m
ils)
– 1
mo
no
layer
tota
l segre
gation
(cf. 0
.5 a
t satu
ration)
13
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Impro
ved 1
100
oC
Cyclic
Oxid
ation
PW
A 1
480 t
o 1
484
1-h
r cycle
s
05
00
10
00
15
00
20
00
S ifi
-10-8-6-4-202
1480,
(ca.
1988)
6.7
ppm
w S
1480,
H2,
1200
oC
/ 1
00 h
r,
0.2
ppm
w S
1484,
(ca.
1998),
1.2
ppm
w S
1484,
H2,
1250
oC
/ 5
0 h
r, 0
.01 p
pm
w S
14
80
, 6
.7 S
(1.5
Ti)
14
80
, 0
.2 S
14
84
, 1
.2 S
14
84
, 0
.01
S
14
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Impro
ved 1
100
oC
Cyclic
Oxid
ation
Ren
eN
4 t
o N
5±Y
, N
6
1-h
r cycle
s
02
00
40
06
00
80
01
00
0
S ifi
-10-8-6-4-202
Rene' N
4
Rene' N
5-
Rene"
N5+
Rene' N
6N
4(4
Al
4T
i)
N5,6
(6A
l)
15
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
1-h
r cycle
s
0200
400
600
800
1000
S ifi
-10-8-6-4-202
Rene'N
5 -
(ca. 1992)
Rene'N
5 -
, H
2-a
nneale
d, 1200
oC
/ 1
00 h
r
PW
A1484,
PC
C m
elt d
esulfurized,
(ca.
1998)
0.3
ppm
w S
N5
-
~3
S
N5
-, H
2
~0
.3 S
14
84
me
lt d
eS
0.3
S
Exceptional 1150
oC
Cyclic
Oxid
ation:
PW
A 1
48
4 a
nd
Re
ne
N5
16
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
1-h
r cycle
s
050
100
150
200
W i ht
-200
-150
-100
-500
50
100 h
r
24 h
r
4 h
r
as-r
eceiv
ed
13
00
oC
, H
2 a
nn
ea
l:
1100
oC
Cyclic
Oxid
ation f
or
EP
M A
lloy 3
9:
5.5
Al
8.3
Ta 2
0C
o 2
Mo
2.3
Cr
4.5
Ru
5.7
Re
5.6
W 0
.4T
i
17
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
1100
oC
Cyclic
Oxid
ation f
or
EP
M A
lloy 3
9:
5.5
Al
8.3
Ta 2
0C
o 2
Mo
2.3
Cr
4.5
Ru
5.7
Re
5.6
W 0
.4T
i
1-h
r cycle
s
050
100
150
200
W i ht
-20
-15
-10-505
100 h
r
24 h
r
4 h
r
as-r
eceiv
ed
All
oy 3
9,
1100
oC
1300
oC
, H
2 a
nn
eal:
18
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Ch
rom
ium
, w
t. %
24
68
10
Aluminum w
2468
conventional S
A
SA
regre
ssio
n
SX
SA
Reduced C
hro
miu
m f
or
Sin
gle
Cry
sta
l S
upera
lloys
N6
N
5
N4
14
80
14
84
CM
SX
10
CM
SX
4C
MS
X 2
EP
M1
02
genera
tion
19
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Ro
om
Tem
pera
ture
,
Mo
istu
re-I
nd
uced
Dela
yed
Sp
allati
on
(M
IDS
)
(NA
SA
GR
C A
necdote
s)
• 1
97
8 N
iAl:
sp
alli
ng
ove
r b
ea
ke
r o
f H
2O
• 1
986 N
iCrA
l:
sulfur
purg
ing (
scale
‘w
ashed’ off)
• 1
989 P
WA
1480:
H2-a
nn
ea
ling
(b
rea
th t
est)
• 1
994 R
ene’1
42,
N5:
H2-a
nnealin
g (
imm
ers
ion t
est)
• 1
998 P
WA
1484:
melt,
H2-a
nnealin
g (
imm
ers
ion)
• 2
002 R
ené N
5:
(im
mers
ion a
coustic e
mis
sio
n)
20
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Mo
istu
re-I
nd
uced S
pallati
on
of
Al 2
O3 S
cale
s
Additio
nal K
ey O
bserv
ations
• 1993,
FeC
rAl-C
e (
Sig
ler,
GM
): m
ore
sp
alla
tio
n in
hu
mid
air,
N2,
Ar
• 1
99
5,
Re
né
N6 (
Sm
ith
, F
razie
r, P
reg
ge
r, N
AW
C):
scale
on h
igh S
spalle
d o
nly
in m
ois
t O
2/ N
2
• 1999,
PW
A1480,
1484,
CM
SX
4
(J
an
akira
ma
n,
Me
ier,
Pe
ttit, P
itt)
:
sp
alla
tio
n f
or
wa
ter
dro
p,
mo
ist
vs d
ry a
ir
• 2
00
0,
Fe
CrA
lY (
To
lpyg
o,
Cla
rke
, U
CS
B):
dela
yed s
cale
bucklin
g in a
ir
• 2
00
3,
Re
né
N5 (
Ma
ris-S
ida
, M
eie
r, P
ett
it, P
itt)
: s
pa
llatio
n in
hig
h P
H2O
air f
or
hig
h s
ulfur
allo
y
21
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Dela
yed T
BC
Failu
re(W
eeken
d E
ffect,
Desk T
op
Sp
allati
on
)
• R
ené N
5: T
BC
bucklin
g g
row
th, m
ois
ture
-assis
ted
su
bcritica
l A
l 2O
3–
bo
nd
co
at
cra
cks
(1
99
7,
Cla
rke
, C
hristia
nse
n,
To
lpyg
o)
(1
99
8,
Se
rgo
, C
lark
e)
• C
MS
X4:
pro
gre
ssiv
e s
cale
debond,
TB
C f
ailu
re
(2
00
0,
Pe
ng
, C
lark
e)
• P
WA
1484: ‘n
o b
ond c
oat’ T
BC
dela
min
ation,
H
2O
im
me
rsio
n
(19
98
, ‘0
2,
‘04
, S
mia
lek)
22
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Aft
er
wa
ter
imm
ers
ion
Undoped N
i15C
r13A
l, Im
mers
ion E
ffects
15 p
urg
ing c
ycle
s, 1120
oC
, 1-h
r
19
86
As
-co
ole
d
23
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
No E
ffec
t of
Wate
r Im
mer
sion
on
H2-A
nn
eale
d S
am
ple
0.0
1 p
pm
w S
PW
A 1
48
4,
12
50
°C/5
0 h
r A
nn
eal,
11
00
°C C
ycl
ic O
xid
atio
n (
10
x)
200 h
r800 h
r2000 h
r
400 h
r +
H2O
800 h
r +
H2O
2000 h
r +
H2O
5 m
m
24
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Wa
ter
Imm
ersi
on
Pro
du
ces
Sca
le S
pa
lla
tio
n t
o B
are
Met
al
Hig
her
S (
1.2
pp
mw
S)
PW
A 1
48
4,
11
00
°C C
ycl
ic O
xid
atio
n
200 h
r800 h
r2000 h
r
5 m
m
400 h
r +
H2O
800 h
r +
H2O
2000 h
r +
H2O
25
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Eff
ect
of
Su
lfu
r C
on
ten
t o
n C
yclic O
xid
ati
on
PW
A 1
484 a
t 1100
o C
Oxid
ati
on
tim
e,
1-h
r cycle
s
0400
800
1200
2000
Specific2
-35
-30
-25-5-4-3-2-101
1.2
pp
m S
as
-re
c’d
0.2
5 p
pm
S
me
lt d
e-S
0.0
1 p
pm
S
H2-a
nn
ea
led
H2O
H2O
26
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Eff
ect
of
Su
lfu
r C
on
ten
t o
n P
S N
BC
TB
C L
ife
PW
A 1
484 C
yclic O
xid
ati
on
at
1100
oC
Oxid
ati
on
tim
e,
1-h
r cycle
s
0400
800
1200
1600
2000
Specific2
-3-2-101
DT
SD
TS
DT
S
0.0
1 p
pm
S
H2-a
nn
eale
d
1.2
pp
m S
as-r
ec’d
0.2
5 p
pm
S
melt
de-S
DT
S =
de
sk
to
p s
pa
lla
tio
n
H2O
(Oth
er
sid
e s
palled
)
27
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
GD
MS
su
lfu
r co
nte
nt,
pp
mw
0.0
10.1
1
TBC del
0
500
1000
1500
2000
Eff
ect
of
Su
lfu
r C
on
ten
t o
n T
BC
Lif
eP
WA
1484,
no
bo
nd
co
at,
cyclic o
xid
ati
on
at
1100
oC
1.4
0.3
5
S(p
pm
)1
1400
life
(h)
+
ed
ge
fa
ilu
res
(ave
rag
e)
critical S
28
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Substr
ate
and T
BC
Inte
rface A
fter
Dela
min
ation (
DT
S)
Hig
h S
14
84
, n
o b
on
d c
oa
t, 2
00
hr,
11
00
°C
Cy
cli
c O
xid
ati
on
(1
0x
)
Fir
st
sid
e s
pra
yed
Seco
nd
sid
e s
pra
yed
5 m
m
29
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Ni
Co
Cr
Ta
Al
Al
Ov
ern
igh
t In
terf
acia
l T
BC
Fai
lure
Hi
S 1
484;
NB
C, 1100
oC
, 2
00
ho
urs
5 μ
m
me
tal
ox
ide
30
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Ide
ali
ze
d S
ch
em
ati
c C
ros
s-S
ec
tio
ns
(not
to s
cale
)
gro
ove
rib
gro
ove
rib
TB
C
PW
A 1
484
10 m
ils T
BC
10 m
ils g
roove
10 m
ils r
ib
10 m
ils w
ide
X,
grid s
pacin
g
TB
C
31
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
1”d
ia.
10
mil
de
ep
gro
ov
e p
att
ern
0.0
50
-0.2
00
" s
pa
cin
g
(vs 2
00
hr
fla
t sid
e)
10
mil
hig
h r
ib p
att
ern
,
0.0
50
-0.2
00
" s
pa
cin
g
(vs 1
50
hr
fla
tsid
e)
AB
Eff
ec
t o
f S
eg
me
nti
ng
by
Gro
ov
es
an
d R
ibs
on
TB
C D
ura
bil
ity
(1
10
0oC
fo
r 2
00
0 h
)
32
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Pla
sm
a S
pra
yed
8Y
SZ
TB
C,
No
Bo
nd
Co
at,
Lo
w S
ulf
ur
PW
A 1
484
10
mil
Rib
s,
1 i
n.
dia
.; I
nte
rru
pte
d O
xid
ati
on
Te
sti
ng
at
11
00
o C
Seg
men
ted
TB
C P
reven
ts F
ailu
re
U.S
. P
ate
nt
6,3
16
,07
8;
No
v.
13
, 2
00
1
Fla
t sid
es (
no
rib
s)
de
lam
ina
te c
om
ple
tely
at
40
0-1
00
0 h
buckle
d
(0.7
1 in. rib s
pacin
g)
buckle
d
(0.3
5 in. rib s
pacin
g)
no b
ucklin
g
(0.1
8 in r
ib s
pacin
g)
no b
ucklin
g
(0.0
9 in r
ib s
pacin
g)
R1
1
00
0 h
R4
1
40
0 h
R1
6
20
00
hR
64
2
00
0 h
33
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Pla
sm
a S
pra
yed
8Y
SZ
, N
o B
on
d C
oat,
Lo
w S
ulf
ur
PW
A 1
484
1100
oC
Cyclic O
xid
ati
on
, 2000 1
-hr
Cy
cle
s
Bu
ckle
d, 2000 h
0.5
in
. ri
b s
pacin
g
No
Bu
ckle
, 2000 h
0.1
25 in
. ri
b s
pacin
g
No
Bu
ckle
, 2000 h
0.2
5 in
. ri
b s
pacin
g
S1
S6
S2
4
Seg
men
ted
TB
C P
reven
ts F
ailu
re
U.S
. P
ate
nt
6,3
16
,07
8;
No
v.
13
, 2
00
1
Fla
t sid
es (
no
rib
s)
de
lam
ina
te c
om
ple
tely
at
40
0-1
00
0 h
34
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Sch
em
ati
c o
f T
BC
(S
cale
) B
ucklin
g F
ailu
re
(after
H.
Evans o
r A
. E
vans,
et
al.)
hT
BC
r b
co
ate
d o
r
cla
mp
ed
ed
ge
s
su
bs
tra
te
TB
C
2
2122
.1
=b
TB
CT
BC
br
hE
()
()(
)T
BC
TB
Ccte
cte
R
ET
+=
11
35
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Eff
ect
of
Rib
bed
TB
C S
eg
men
t S
ize o
n L
ife
10 m
il 8
YS
Z,
No B
ond C
oat, L
ow
S P
WA
1484
Bu
cklin
g l
ife,
t f, h
r
0500
1000
1500
2000
Segment size, D,
0.0
0.5
1.0
EE
EE
11
50
oC
11
00
oC
E =
Ed
ge d
ela
min
ati
on
(no
rib
s)
no
failu
re
2R
* B, 1150
2R
* B, 1100
100 h
r cycle
s
1 h
r cycle
s
36
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
1-h
r cyc
les
11
01
00
10
00
s p e c i f i c w e i g h t c h a n g e , m g / c m2
-4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
mo
istu
re-in
du
ce
d lo
ss
(bre
ath
effects
)
ne
t sa
mp
le w
eig
ht
imm
ers
ion
Effect o
f Mo
istu
re E
xpo
sure
afte
r
Cyc
lic O
xidation
of R
ene
'14
2 a
t 1
15
0o C
R1
42
-8,
1 m
m
12
80
oC
, 1
00
hr,
1 a
tm H
2
19
94
as
-co
ole
dim
me
rse
d
37
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
38
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
39
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
40
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Eff
ect
Y C
on
ten
t an
d H
2 A
nn
ealin
g o
n F
inal
Weig
ht
Ch
an
ge
(Ren
e'N
5 a
fter
1000 1
-hr
Cycle
s a
t 1150
oC
)
Y levels
, p
pm
w
016
24
31
48
53
67
88
103
105
weight2
-40
-30-101
as-r
ece
ive
d
H2-a
nn
ea
led
41
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Th
e E
ffect
of
Y/S
Rati
o o
n O
xid
ati
on
Beh
avio
r(R
en
e'N
5 o
xid
ized
at
1150
o f
or
1000 1
-hr
cycle
s)
Ytt
riu
m / S
ulf
ur
rati
o, p
pm
a/p
pm
a
01
23
45
67
8
1000 hr. w2
-50
-40
-30
-20
-100
10
H2-a
nn
eale
d
as
-re
ce
ive
d
YS
Y2O
2S
PW
A 1
48
4
(Aim
on
e, 1
99
2)
Y2S
3
42
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Eff
ect
of
Wa
ter
Imm
ers
ion
on
Sp
alli
ng
(Rene'N
5 a
fter
500 1
-hr
Cycle
s a
t 1150
oC
)
Y L
eve
ls, p
pm
w
01
62
43
14
85
36
78
81
03
10
5
spall due to 2
0.0
0.5
1.0
1.5
as-r
ece
ive
d
H2-a
nn
ea
led
43
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
as-r
eceiv
ed
H2-a
nn
eale
d
bare
meta
l spalli
nga
s-c
oole
d
afte
r im
me
rsio
n
no
sp
alli
ng
Eff
ect
of
Wate
r Im
mers
ion
on
Sp
allati
on
Rene’N
5+
103Y
, 1150
oC
, 5
00
hr
44
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
1150
oC
Cyclic O
xid
ati
on
of
Ren
e'N
5
(12
50
o C
, 100 h
r H
2)
1-h
r cycle
s
02
00
40
06
00
80
01
00
0
specif2
-2.0
-1.0
0.0
1.0
2.0
-40.6
mg
/cm
2 @
10
00
hr
0 Y
, 2.6
S
0 Y
, <
0.0
1 S
(pp
mw
)H
2O
H2O
H2
anneale
d
as-r
eceiv
ed
45
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
(12
50
o C
, 100 h
r H
2)
1-h
r cycle
s
02
00
40
06
00
80
01
00
0
spec2
-2.0
-1.0
0.0
1.0
2.0
50
Y, 6
.2 S
50 Y
, 5.4
S
(pp
mw
)
H2
anneale
d
H2O
H2O
Imm
ers
ion
Eff
ect
for
Ren
eN
5 (
+Y
)1
15
0oC
, 1
-hr
cycle
s,
±Y
, H
-an
ne
alin
g
20
00
46
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Mo
istu
re-I
nd
uced
Dela
yed
Sp
all
ati
on
(M
IDS
)
Acoustic E
mis
sio
n d
uring I
mm
ers
ion
(pre
-oxid
ize
d R
en
e’N
5+
Y,
10
00
1-h
r cycle
s @
11
50
oC
)
050
10
0
15
0
20
0 05
10
15
20
25
Imm
ers
ion
tim
e,
hr
Number of events
050
0
10
00
15
00
20
00
Cumulative Energy
as-r
ece
ive
d
6%
sp
alle
d
H2-a
nn
ea
led
0.3
% s
pa
lled
(42):
8.5
s
(6):
0.6
s
(82):
33.5
s
(10):
2.4
s
(2):
0.0
4 s
G.N
. M
ors
cher
, 2000
47
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
EB
-PV
D 7
Y2O
3-Z
rO2 T
BC
Ni(
Pt)
Al
bo
nd
co
at,
Re
ne
N5,
Laser
HH
FT
, 1280/1
050
oC
, 2
00
x2
hr
30 μ
m
Al 2
O3
scale
Zh
u,
20
01
7Y
SZ
Bo
nd
co
at
1280
oC
1050
oC
48
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Del
ayed
Des
k T
op F
ailu
res
of
EB
PV
D T
BC
Ni(
Pt)
Al
bo
nd
co
at
on
Re
ne
’N5
; 1
13
5oC
360-7
20 c
ycle
s t
o f
ailu
re;
45 m
in/
ho
t cycle
360
560
560
620
660
720
1 in
ch
Zh
u,
20
05
49
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
PV
D T
BC
Fail
ure
Locu
s (
Exp
ose
d s
ub
str
ate
)
5
60
cycle
s @
11
35
oC
,
2
00
, 1
00
0,
50
00
x,
BS
E
C
A
B
CCB
are
Ni(
Pt)
Al
Bo
nd
co
at
Al 2O 3
ZrO2
A larg
e p
ort
ion o
f th
e T
BC
failu
re
is a
t th
e s
cale
-meta
l in
terf
ace
50
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Mois
ture
-In
duced D
ela
yed F
ailu
re
EB
-PV
D R
E-Y
SZ,
Ni(
Pt)
Al, R
en
e N
5,
1150
oC
, 300 c
ycle
s
Oct. 1
0, 2006
51
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Slo
w (
Subcritical) C
rack G
row
th (
?)
In b
ulk
Al 2
O3 :
(We
ide
rho
rn,
Ritte
r, N
ag
ab
ho
osh
an
am
, K
otc
hic
k,
Eb
rah
am
i, 1
96
8-2
00
0)
•v
c
10
-6 t
o 1
0-3
m/s
•A
l 2O
3 +
3 H
2O
= 2
Al(O
H) 3
Fo
r A
l 2O
3 s
ca
le –
NiC
rAl
inte
rfa
ce
:( A
co
ustic e
mis
sio
n,
Sm
iale
k-M
ors
ch
er,
20
02
)
•vc
10
-3 t
o 1
02 m
/s
•Al +
3 H
2O
= A
l(O
H) 3
+ 3
/2 H
2
52
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Am
bie
nt
Mo
istu
re-I
nd
uced
Hyd
rog
en
Em
bri
ttle
men
t o
f In
term
eta
llic
s(c
om
pelli
ng a
nalo
gy t
o d
ela
yed s
cale
spalla
tion)
• E
xtr
insic
ally
brittle
M3X
com
pounds:
(Ni,F
e,C
o) 3
(Al,S
i,T
i)
• E
mbrittle
d b
y m
ois
t air,
not
dry
O2,
or
vacuum
:2
Al +
3H
2O
=
• M
ax e
ffect
near
room
tem
pera
ture
• O
nly
at
slo
w v
s h
igh s
train
rate
s
(Sto
loff
et
al.,
Liu
et
al.)
1994 M
RS
Keynote
Lectu
re
53
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Inte
rmit
ten
t N
atu
re o
f C
rack G
row
th in
Hyd
rog
en
Em
bri
ttle
d H
igh
Str
en
gth
Ste
el
“…
cra
ck p
rop
ag
ati
on
is a
dis
co
nti
nu
ou
s p
rocess…
…
furt
her
gro
wth
mu
st
aw
ait
dif
fusio
n o
f h
yd
rog
en
…
…
the p
late
au
s…
are
th
e ‘
seco
nd
ary
’ in
cu
bati
on
peri
od
s…
”
A.R
. T
roia
no
, C
hair
man
, D
ep
t. o
f M
eta
llu
rgy
Case In
sti
tute
of
Tech
no
log
y
1959 E
dw
ard
de M
ille
Cam
pb
ell L
ectu
re, A
SM
54
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Fig
. 11. R
esis
tan
ce In
cre
ase a
s a
Fu
ncti
on
of
Tim
e F
or
Un
ifo
rmly
Hyd
rog
en
ate
d S
pecim
en
s T
este
d in
th
e S
tress R
an
ge o
f D
ela
yed
Failu
re
(Tro
ian
o,
1959)
55
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Hy
dro
ge
n E
mb
ritt
lem
en
t a
nd
Mo
istu
re-I
nd
uced
Dela
yed
Failu
res
(ste
els
, N
i-a
lloys,
alu
min
ide
s) Inte
rfacia
l w
eakenin
gIn
terg
ran
ula
r and c
leavage
Mois
ture
effects
,
Dela
yed
Rm
Tem
p. fa
ilure
Dela
yed
failu
re a
t R
m T
em
p.
Hydro
gen d
iffu
sio
n,
Inte
rmit
ten
t spalla
tion
Inte
rmit
ten
t cra
ck g
row
thT
ensile
str
ess s
tate
H, S
decre
ase M
-Al 2
O3 b
on
dH
, S
decre
ase M
-M b
on
dT
heore
tical str
ength
Neg
ati
ve s
yn
erg
yN
eg
ati
ve s
yn
erg
yH
+ S
segre
gation
Inte
rfacia
l d
e-s
calin
gH
-em
bri
ttle
men
tC
ath
odic
charg
ing
Inte
rfacia
l w
eakenin
gIn
terg
ran
ula
r e
mbrittle
ment
Sulfur
segre
gation
Scale
Sp
alla
tio
n
(1985-2
005)
Allo
y F
ractu
re
(1951-1
989)
Co
mm
on
Featu
res
Oc
ca
m’s
Ra
zo
r:
ke
ep
it
sim
ple
an
d d
raw
fro
m k
no
wn
ex
pe
rie
nc
e
56
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
_
N5
Pt
1 N
H2S
O4
AV
H2
O2
+
0-1
00 m
A
- 2V
to +
2V
Sta
nd
ard
Ele
ctro
chem
ica
lC
ath
od
ic H
yd
rog
en C
ha
rgin
g
An
od
ic:
+1
.3V
, H
2
Ca
tho
dic
: -2
.0V
, A
.R.
Cri
tic
al
ex
pe
rim
en
t:T
est
wheth
er
hydro
gen c
harg
ing c
auses s
cale
dela
min
ation
(e.g
., H
-em
brittle
ment
of
Ni 3
Al+
B,
Kuru
vill
a,
Sto
loff
, 1
98
5)
N5
57
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
1 m
m
De-s
calin
gD
iss
olu
tio
nH
2 b
liste
rs
1 m
m
-2.0
V0
.0 V
to +
2.0
V
to -
3.0
V
1 m
m1 m
m
No
eff
ect
58
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Exp
osed
Ni(
CrA
lWC
o)
su
bstr
ate
Al 2
O3
Pt
HfO
2
Al 2
O3
Ca
tho
dic
De
-Sc
ali
ng
of
Re
ne
’N5
1 h
r @
-2
.0 V
in
1N
H2S
O4
TaC
Al 2
O3
Oxid
e im
pri
nts
(S
E)
in e
xp
osed
meta
l
Ex
po
se
d m
eta
l
-2.0
V
59
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
20
0 μ
m
2 μ
m
Ca
tho
dic
Hy
dro
ge
n C
rac
kin
g a
nd
Bli
ste
rin
g’ e
tch
ing
ba
re R
en
e’N
5,
-3.0
V,
1 N
H2S
O4
60
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Su
bst
rate
Incu
bati
on
Inta
ct
H, S
, (C
?)
syn
ergis
tic
wea
ken
ing
spal
l3 <
<
incu
bat
e2<
<<
inta
ct1
e-3H
+A
l++
+(O
H) 33
H2O
ca
tho
de
anode
CT
EC
TE
12
Al 2
O3
Sp
all
ed3
YS
Z T
BC
Mois
ture
-Induced H
ydro
gen E
mbrittle
ment:
Dela
yed
Al 2
O3 (
an
d D
es
k T
op
TB
C)
Sp
all
ati
on
un
zip
pin
g i
nte
rfa
ce
61
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Sum
mary
of M
IDS
Phenom
enolo
gy
(caveats
)
•In
term
edia
te s
ulfur
conte
nt
•M
atu
re,
cycle
d (
dam
aged)
scale
s
(with e
xposed inte
rface t
o h
um
id e
nvironm
ent)
•W
ate
r im
mers
ion a
s a
ccele
rate
d t
est
•In
cre
ases s
palla
tion,
but m
ay n
ot b
e n
ece
ssa
ry
•H
-charg
ing f
aile
d a
dhere
nt, b
ut
matu
re s
cale
s
•(S
tabili
zation f
or
inte
rmedia
te P
H2O a
gin
g?)
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Co
nn
ecti
on
s a
nd
Pro
po
sed
Hyp
oth
esis
1.
Pri
mary
scale
(T
BC
) chem
ical effect due to sulfur.
2.
Seco
nd
ary
, dela
yed A
l 2O
3 s
cale
(and T
BC
) spalla
tion
= m
ois
ture
effects
(M
IDS
, D
TS
).
Cath
odic
H-c
harg
ing
causes m
assiv
e inte
rfacia
l A
l 2O
3 s
cale
spalla
tion a
t very
low
curr
ent (1
mA
at -2
V).
Inte
rfa
cia
l h
yd
rog
en
em
bri
ttle
me
nt
is r
es
po
ns
ible
fo
r
mo
istu
re-i
nd
uced
dela
yed
failu
re o
f A
l 2O
3 s
cale
s a
nd
thu
s c
on
trib
ute
s t
o D
esk T
op
Sp
allati
on
of
TB
C’s
.
63
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
•P
WA
1484,
Ren
e1
42
, R
en
e N
5
–C
riti
cal
Y/S
rati
o ~
1:1
ato
mic
(3:1
by w
eig
ht)
–H
2-a
nneal im
pro
ves a
dhesio
n
(cyclic
+ im
mers
ion)
–E
vid
ence t
hat
mo
istu
re-a
ssis
ted
sp
allati
on
,
is a
hy
dro
ge
n e
mb
ritt
lem
en
t phenom
enon
64
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
1-h
r cycle
s
0200
400
specific w2
-2.0
-1.0
0.0
1.0
2.0
tk
2
tk
1+
= g
row
th
= s
palla
tion
)tk,t
k(f
A/
W
:M
od
elin
g
Oxid
atio
nC
yclic
21
=
pa
ralin
ea
r m
od
el fitt
ing
W/A
65
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Cyclic O
xid
ati
on
Mo
delin
gB
asic
Featu
res
• P
ostu
late
an
oxid
e:
(Al 2
O3,
NiO
,…);
Sc =
mass o
xid
e/o
xygen
• D
efi
ne t
he k
ineti
c g
row
th b
eh
avio
r:
(para
bolic
kp,p
ow
er
law
k, m
…)
• D
efi
ne t
he s
pallin
g a
lgo
rith
m:
(% s
pall
= Q
o·
exis
ting s
cale
)
(oute
r la
yer
vs b
are
meta
l segm
ents
)
• P
erf
orm
ite
rati
ve c
alc
ula
tio
ns;
bo
okkeep
ing
oxygen g
ain
, oxid
e lost, m
eta
l consum
ed,…
66
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
GR
OW
TH
para
bo
lic
(oxy
gen m
ass g
ain
)p
ow
er
law
log
ari
thm
ic
SP
AL
L F
RA
CT
ION
SP
AL
LA
TIO
Nu
nifo
rm t
hic
kn
ess
(oxi
de m
ass lo
ss)
Mo
nte
Carl
o (b
imo
dal)
DIC
OS
M
p - k
p; (M
on
ceau
)
()
tk
AW
p=
2
()
tk
AW
p
m=
()
()
{}
mc
kt
lnA
W1
+=
1=
=;
WQ
Fr'
oS
1=
=;
WQ
Fr'
oS
thic
kness
scale
tota
l
depth
spall
Rspall=
segm
ent)
(thic
kest
fractio
n
are
a
spall
FA=
ypro
babili
t
(are
a)
spall
p=
Cycl
ic O
xid
ati
on
Mod
elin
gC
om
mon V
aria
tions
(CO
SP
)
67
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
cycl
e
j =
1
j =
2
j =
3
j =
4
inta
ct o
xid
e
spall
edoxid
e
i =
1 2
3
4
5
6
7
8
9 10 =
no,
FA
= 1
/10
Sch
ema
tic
of
Det
erm
inis
tic
Inte
rfa
cia
l S
pa
llin
gM
od
elA
) cy
cle
nu
mb
er,
(j),
les
s th
an n
um
ber
of
area
seg
men
ts,
(no)
j =
5
FA
= s
pall
are
a f
racti
on
, =
1/n
o tk
jh
h
68
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
1.
Un
ifo
rm
2.
Mo
nte
Carl
o
3.
DIC
OS
M
69
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
1-h
r cycle
s
0200
400
600
800
specific we2
-5.0
0.0
5.0
fraction oxid
-0.0
05
0.0
00
0.0
05
Fsp
all
Wr
W/A
Al
O2
Wsp
all
j oj m
ax
CO
SP
Mo
del O
utp
uts
Al 2
O3 s
ca
le,
kp
= 0
.01
mg
/cm
2,
t =
1 h
r,
Qo =
0.0
02
cm
2/m
g,
= 1
.0
70
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Pa
ram
etr
ic S
tud
y:
Eff
ec
t o
f k
p
(para
bolic
, A
l 2O
3,
Qo=
0.0
02,
t=1 h
r)
1-h
r cycle
s
02
00
40
06
00
80
01
00
0
specif2
-10
.0
-5.0
0.0
0.0
01
0.0
02
0.0
05
0.0
10
0.0
20
0.0
50
kp
(mg
2/c
m4h
r)
71
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Sem
i-u
niv
ers
al
Cyclic O
xid
ati
on
Cu
rve
(DIC
OS
M-G
SA
mo
del)
No
rmalized
cycle
nu
mb
er,
JU =
j/jm
ax
01
23
45
67
89
10
Normalized weig
WU
= (W/A)j
/ (W/A)max
-12
.0
-10
.0
-8.0
-6.0
-4.0
-2.0
0.0
2.0
Jm
ax
Jo
1.0
1.5
2.0
Sc
= 3
.0
4.0
5.0
Sc=
sto
ich
iom
etr
ic
c
on
sta
nt
[]
23
21
32
1u
uu
JJ
W=
72
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Eff
ect
of
Su
lfu
r C
on
ten
t o
n t
he
1100
oC
Cyclic O
xid
ati
on
of
PW
A 1
480
(DIC
OS
M fit: dashed lin
es)
ox
ida
tio
n t
ime
, 1
-hr
cy
cle
s
0100
200
300
400
500
i ht
-15
-10-50
6.7
3.9
1.5
0.8
0.1
2
pp
mw
S
73
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
Cri
teri
a:
Un
ive
rsa
l C
yc
lic
Ox
ida
tio
n L
ife
Ma
p
PW
A 1
480,
1100
oC
no
rma
lize
d k
p,
{j*k
pt(
Sc-1
)2/(
3/4
W* m
)2}
0.0
10
.11
10
Anormalized sp
0.11
10
10
0
10
00
0.1
2
0.8
1.5
6.7
excessiv
e
spalla
tion
min
imal g
row
th
and s
palla
tion
WA
l fa
ilu
re l
ocu
s
10 m
g/c
m2, 1000 h
3.9
Su
lfu
r, p
pm
w
excessiv
e
gro
wth
74
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
•C
yclic
Mod
els
–U
ser
– f
riendly
CO
SP
for
Win
dow
s
(mu
ltip
le m
od
els
, in
sta
nt
plo
ts,
up
loa
ds e
xp
t’l d
ata
)
–P
roduce t
ypic
al plo
ts;
fits
ideal allo
y b
ehavio
r
–D
ICO
SM
, p
-kp
allo
w a
naly
tical solu
tions,
trends,
univ
ers
al fa
ilure
maps.
75
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
1.
About
0.2
ppm
w S
(or
Y/S
ratio o
f 1:1
) is
critical.
2.
Inte
rfacia
l hydro
gen e
mbrittle
ment
causes m
ois
ture
-
induced d
ela
yed f
ailu
re (
MID
S)
of
Al 2
O3 s
cale
s.
3.
Ideal cyclic
behavio
r can b
e a
naly
zed b
y m
odels
.
Fin
al R
ecap
76
Nat
iona
l Aer
onau
tics
and
Spa
ce A
dmin
istr
atio
n
ww
w.n
asa.g
ov
•J.L
. S
mia
lek: “O
xid
ation R
esis
tance a
nd C
ritical S
ulfur
Conte
nt of S
ingle
Cry
sta
l S
upera
lloys,”
Tra
nsactions o
f th
e A
SM
E, V
ol.
120, 1998, p
p. 370-3
74.
•J.L
. S
mia
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