NASA Technical Reports Server (NTRS) 20150002078: Alumina-Forming MAX Phases in Turbine Material Systems

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by  NASA Technical Reports Server (NTRS)

Alumina-Forming MAX Phases in
Turbine Material Systems
James L. Smialek, Bryan J. Harder,
Anita Garg, James A. Nesbitt,
NASA Glenn Research Center, Cleveland, OH
39th ICACC Daytona Beach, January 25-30, 2015
MAX Phases, M AX
n n-1
(Barsoum, 2001,
about 60 phases; >300 papers)
Oxidation Resistant:
M = Ti, Cr Ti AlC
3 2
A = Al, (Si) Ti AlC
2
X = C, (N) Cr AlC
2
Strain Tolerant Kinking
Cr Al(Si)C W. Yu, S. Li, W.G. Sloof, 2007
2
Ti AlC “MAXthal 211” (Kanthal)
2
M. Sundberg, et al., 2004
15 (cid:80)m Al O
8000 cycles to 1350oC! 2 3
Purpose: Relate Al-MAX phases to
coatings applications/turbine environment
1) High temperature (cid:68)-Al O kinetics
2 3
2) High pressure burner rig
3) YSZ Thermal Barrier Coatings
4) Superalloy/MAX Phase Hybrid
5) Hot corrosion
Coating Motivation and Rationale
Ti AlC , Ti AlC, Cr AlC
3 2 2 2
• (cid:68)-Al O formers
2 3
• CTE close to YSZ, (cid:68)-Al O
2 3
• Strain tolerance, nano-laminate shear
• Thermal shock resistance: ~1400(cid:113)C quench
• K (cid:124) 7 MPa/m1/2
IC
Hybrid Concepts (EBC/TBC) Enabled by MAX Phases
Intermediate CTE, Strain Tolerance, YSZ Compatibility
1300(cid:113)C Bond Coats (?)
YSZ 10 Top Coat
Al O 9 Scale
2 3
Ti AlC 8 Critical interface
2
Bond Coat
Ti AlC 9
3 2
Rene N5 15
Substrates
SiC 4
CTE, 10-6/(cid:113)C
Purpose: Relate Al-MAX phases to
coatings applications/turbine environment
1) High temperature (cid:68)(cid:68)-Al O kinetics
2 3
‒ grain boundary diffusivity
‒ transient TiO growth
2
‒ cubic kinetics
Schematic of Alumina Scale Transport
Gas, high pO
2
0.2 atm (2x104 Pa)
Al
grain
Al O
2 3
boundary
scale
G
i
O (cid:71), width
Equilibrium, low pO
2, interface
~ 10-28 atm (10-23 Pa)
M-Cr-Al alloys
2δ
D (cid:124) fD (cid:32) D (short circuit diffusion) (cid:33)(cid:33) D
eff gb gb lattice
G
i
Modified Wagner: Derived k vs (cid:71)D Relation:
p gb,O
(oxidation product (cid:51) (cid:124) constant)
P ,gas
O
2
dx
(cid:179)
k (cid:32) 2x (cid:124) D d ln P (Wagner eqn.)
p,instant eff ,O O
dt 2
P ,interface
O
2
(cid:51) = k (cid:152) G (cid:124) 12(cid:71)D
i p,instant instant gb,O,interface
(cid:63) If scale grain size available,
a nearly invariant diffusivity can be estimated.
Scale Grain Boundary Diffusivity
MAX Compounds and FeCrAl(Zr) Alloy
10-20
,
t
c
u
d 10-22
o
r c
p e
s
n
/
o3
m Smialek FeCrAl(Zr)
i
s 10-24
u , Tallman Ti2AlC
O
f
f b, Song Ti2AlC
i
g
d
D #
Wang Ti AlC
n (cid:71) 3 2
e 10-26 Wang Ti AlC
3 2 375 kJ/mole
g
y
x Lee Cr2AlC
o
Hajas Cr AlC
2
10-28
6.0 7.0 8.0
4 -1
1/T, 10 K
Scale Grain Boundary Diffusivity
MAX Compounds and FeCrAl(X) Alloys
10-20
,
t
c Q =375 +/- 25 kJ/mole
u gb,O
d 10-22
o
r c
p e
s
n
/
o3
m
i
s 10-24

u ,
O
f
f b,
i
g
d
D
Literature

n (cid:71)
e 10-26 3 MAX phases
g
8 FeCrAl(X) alloys ~1 diffusivity
y
x
13 Studies
o
10-28
6.0 7.0 8.0
4 -1
1/T, 10 K