DEVELO

PMEN

T OF N

ASA'S AD

VAN

CED

ENVIR

ON

MEN

TAL BAR

RIER

C

OATIN

GS FO

R SIC

/SIC C

OM

POSITES: PR

IME-R

ELIANT D

ESIGN

AND

D

UR

AB

ILITY PERSPEC

TIVES

Dongm

ing Zhu

Materials and S

tructures Division

NA

SA

John H. G

lenn Research C

enter C

leveland, Ohio 44135

The work w

as supported by NASA

Fundamental Aeronautics Program

(FAP) Transformational Tools

and Technologies (TTT) Project

Advanced Ceram

ic Matrix C

omposites:

Science and Technology of Materials, D

esign, Applications, Performance and Integration

An EC

I Conference, Santa Fe, N

M

Novem

ber 5-9, 2017

1

NASA

’s Advanced Environmental B

arrier Coating System

s for C

eramic M

atrix Com

posites (CM

Cs):

Enabling Technology for N

ext Generation Low

Em

ission, High E

fficiency and Light-W

eight Propulsion, and E

xtreme E

nvironment M

aterial System

s —

NASA

Environmental B

arrier Coatings (EB

Cs) developm

ent objectives •

Help achieve future engine tem

perature and performance goals

• E

nsure system durability – tow

ards prime reliant coatings and m

aterial systems

• E

stablish database, design tools and coating lifing methodologies

Hybrid E

lectric Propulsion A

ircraft and C

oatings (UH

TC

C)

• Im

prove technology readiness

Entry, D

escending and Landing: U

ltra High C

eramics

Fixed Wing S

ubsonic and Supersonics A

ircraft

2

Temperature

Capability

NA

SA Environm

ental Barrier C

oating Developm

ent Goals

• E

mphasize tem

perature capability, performance and durability

• Develop 2700°F environm

ental barrier coating technologies -For 2400°F (1316°C

) and 2700°F (1482°C) C

eramic M

atrix Com

posites (CM

Cs) in

support of next generation turbine engines -Focus on advanced C

MC

combustors and highly loaded turbine airfoils

-Particularly also em

phasize highly loaded turbine blades

Step increase in the m

aterial’s temperature capability

Temperature

3000°F SiC/SiC

CM

CCapability

(T/E(T/EBBC)C) ssuurfarfaccee

airfoil and combustor

3000°F+ (1650°C+)

technologies 2700°F SiC

/SiC thin

2700°F (1482qC)

turbine EBC

systems for

* Recession: <5 m

g/cm2 per 1000 hr (40-50 atm

., Mach 1~2)

** Com

ponent strength and toughness requirements

Gen II –

Currentcomm

ercialG

en IIIG

en. IV

Increase in 'T

G

across T/EBC

Single Crystal Superalloy

Ceramic M

atrix Composite

Gen II – Current com

mercial

en III G

en. IV

Increase in 'T across T/EB

C

Single Crystal Superalloy

Ceramic M

atrix Composite

2800ºFcom

bustor TB

C

2500ºFTurbine TB

C

CM

C airfoils

2700°F (1482°C) G

en III SiC

/SiC

CM

Cs

2400°F (1316°C) G

en I and Gen II SiC

/SiC

CM

Cs

2000°F (1093°C)

GGenen II

YYearear

3

Outline

─ Environm

ental barrier coating systems: tow

ards Prime-R

eliant system

s •

Thermom

echanical, environment and therm

ochemical stability of E

BC

s •

Prim

e-reliant EB

Cs, initial design approach and requirem

ent

─ A

dvanced environmental barrier coating system

s (EBC

s) for C

MC

airfoils and combustors

• N

AS

A advanced turbine EB

C coating system

status •

Developm

ent and testing, durability perspectives

─ D

esign tool and life prediction perspectives of coated CM

C

components

• A

dvanced Testing •

Em

phasizing thermom

echanical, environment and therm

ochemical

interactions

─ Sum

mary and future directions

4

SiC

/SiC

CM

C

Prime-R

elaiant EBC

Systems for Si-B

ased Ceram

ic Matrix

Com

posites−

NASA’s advanced environm

ental barrier and bond coat development: P

rime-reliant

designs •

High toughness and low

conductivity EB

C top coat

• A

lternating Com

position Layered Coatings (A

CLC

s) and composite coatings,

including improving im

pact resistance •

Advanced doped m

ulticomponent E

BC

s •

Prim

e-reliant designed bond coats •

Ultim

ately environmental resistant C

MC

s with high therm

al conductivities H

fO2 -Y

2 O3 -Yb

2 O3 -G

d2 O

3 -(SiO

2 )e.g.,

HfO

2 -Y2 O

3 -Yb2 O

3 -Gd

2 O3 -Ta

2 O2 -TiO

2 -(SiO

2 ) Low

expansion alloyed-HfO

2 , and HfO

2 aluminates

Interlayer R

E doped Hf, H

f RE silicate and/or m

ulti-rare earth silicate EBC

s 2700F bond coats

5

Fundamental R

ecession Issues of CM

Cs and EB

Cs

-R

ecession of Si-based Ceram

ics (a) C

onvective; (b) Convective w

ith film-cooling

-Low S

iO2 activity E

BC

systems

-Advanced rig testing and modeling

Com

plex recession behavior of CM

C and E

BC

s studied in NA

SA H

igh P

ressure Burner R

ig, included film-cooled recession

SiO2 + 2H

2 O(g) = Si(O

H)4 (g)

Recession rate = const. V

1/2 P(H

2O) 2/(P

total ) 1/2

Com

bustion gas

SiO2 + 2H

2 O(g) = Si(O

H)4 (g)

Com

bustion gas

Cooling gas

(a) (b)

6

Continued

ions of environm

ental barrier coatings -EB

C system

s, improved stability in

tability evaluated on S

iC/S

iCC

MC

s in high velocity, high pressure burner

Fundamental R

ecession Issues of CM

Cs and EB

Cs -

―

EB

C s

rig environment

SiC Wt. Loss (mg/cm2)

-15

-10 -5 0

1385 C

1446 C

1252 C

1343 C

Robinson and Sm

ialek, J. Am

. Ceram

Soc. 1999

°

°

°

°

0 20

40 60

80 100

Exposure Tim

e (hrs)

-Early generat

turbine environments

Com

bustor coating Turbine coating

HfO

2 based low k -A

PS H

fO2 based low

k – EB-PV

D

7

Fundamental R

ecession Issues of CM

Cs and EB

Cs -

Continued

―

E

BC

stability evaluated on SiC

/SiC

CM

Cs in high velocity, high pressure burner rig environm

ent

0.001

0.01

0.1 1 100.0005 0.00055 0.0006 0.00065 0.0007 0.00075 0.0008

Specific weight change, mg/cm2-h

1/T, K-1

1300Tem

perature, °C

1400 1500

12001600

SiC/SiC

under high velocity BSA

S Baseline

1100 1000

Tyranohex SA (6 atm

, 200m/s)

Tyranohex SA (16 atm

, 30m/s)

NA

SA EB

C stability devlopm

ent goal: 5 mg/cm

2 -h

Com

bustor coating Turbine coating

HfO

2 based low k -A

PS H

fO2 based low

k – EB-PV

D

High pressure burner rig, 16 atm

, 31 hr -E

arly generations of environmental barrier coatings -E

BC

systems

8

failure

Environmental B

arrier Coating in Sim

ulated Load-Fatigue Testing

Environments (Laser H

igh Heat Flux R

ig) -

EB

C Yb

2 SiO

5 /Yb2 S

i2 O7 /S

i on Melt Infiltrated (M

I) Prepreg S

iC/S

iC C

MC

substrates -

Tested in air, furnace isothermal at 1316°C

; and in heat flux steam, at T

EBC 1316°C

, TC

MC

at ~1200°C

-

Lower C

MC

failure strain observed in the steam-heat flux test environm

ent

failure

failure

failure

Fatigue strains (amplitudes) – Tim

e Plot Therm

al conductivity – Time Plot

In steam-jet, EB

C cracking and

recession

-Ytterbium

mono-silicate recession observed in the test

-Therm

al conductivity for monitoring coating delam

ination

9

Environm

ental Barrier C

oating in Simulated Load-Fatigue

Testing Environments (Laser H

igh Heat Flux R

ig) -Continued

-C

rack and recession failure in air and steam tests

In Air; EB

C cracking

In steam; EB

C cracking and volatility

Com

p onent

Type C

onc., A

t%

Conc.,

Wt%

, O

C

alc 49.07

9.59 Si

Calc

9.79 3.36

Yb C

alc 41.14

87.04 Total

100.00 100.00

EDS 25D

25D

10

Advanced NASA

EBC

Developm

ents

NA

SA

advanced EB

C system

s emphasizing high stability H

fO2 -and ZrO

2 -RE

2 O3 -S

iO2 E

BC

system

s and HfO

2 -Si and R

are Earth – S

ilicon bond coat systems

― N

AS

A m

ulticomponent R

are Earth R

E2 S

i2-x O7-2x , such as (Yb,G

d,Y) 2 Si2-x O

7-2x environmental

barrier systems

― R

are earth-doped HfO

2 -ZrO2 , and H

fO2 -doped R

are Earth (R

E) silicates are am

ong the advanced E

BC

systems

• Im

proved high temperature stability and creep strength;

• Facilitating nano-cluster form

ation with high concentration rare earth com

pound phases; •

Improving C

MA

S resistance

TEM-EELS

Com

position map

11

NA

SA EB

C B

ond Coat System

s N

AS

A E

BC

System

s •

HfO

2 -RE

2 O3 -S

iO2 /R

E2 S

i2-x O7-2x environm

ental barrier systems

• C

ontrolled silica content and rare earth dopants to improve E

BC

stability, toughness, erosion and C

MA

S resistance

• H

fO2 -S

i based bond coat, controlled oxygen partial pressure •

Advanced rare earth-S

i composition system

s for 2700°F+ long-term applications

• E

arly RE

2 O3 -S

iO2 -A

l2 O3 or YA

G S

ystems

• D

evelop prime-reliant com

posite EB

C-C

MC

s, HfS

iRE

(CN

) systems

Bond coat systems for prime reliant EBCs; capable of self-healing %

1212

Developm

ent of Advanced H

fO2 -Si B

ond Coats

– C

oating architecture and HfO

2 contents can be effectively controlled and optim

ized –

Si:H

f atomic ratio preferably 2:1 – 1:1

– R

eported Spinodal decom

position of hafnium-silicate system

s

100 100

Silicon concentration, at%

80 80

60 60

40 40

20 20

Si

O

Oxygen concentration, at% 0

0 0

1020

3040

50 H

afnium concentration, at%

13

Microstructures of Furnace C

yclic Tested GdYbSi(O

) EBC

System

s —

C

yclic tested cross-sections of PV

D processed YbG

dSi(O

) bond coat —

S

elf-grown rare earth silicate E

BC

s and with som

e RE

-containing SiO

2 rich phase separations —

R

elatively good coating adhesion and cyclic durability

1500°C, in air, 500, 1 h cycles /

B

A

-C

omplex coating architectures

after the testing -

Designed w

ith EB

C like

compositions – Self-grow

n E

BC

s

Com

position (mol%

) spectrum A

rea #1 SiO

2 67.98

Gd2O

3 11.95

Yb2O

3 20.07

Com

position (mol%

) spectrum A

rea #2 SiO

2 66.03

A

B Gd2O

3 10.07

Yb2O

3 23.9

14

Microstructures of C

yclic Tested GdYbSi(O

) EBC

System

s-Continued

—

Cyclic tested cross-sections of P

VD

processed YbGdS

i(O) bond coat

—

Self-grow

n rare earth silicate EB

Cs and w

ith some R

E-containing S

iO2 rich phase separations

—

Interface growth instability

1500°C, in air, 500, 1 hr cycles

Outlined area

SpotC

omposition (m

ol%)

SiO2

66.72 G

d2O3

8.62 Y

b2O3

24.66

Com

position (mol%

) SiO

2 96.15

Gd2O

3 1.2

Yb2O

3 2.64

15

Advanced EBC

developments – Som

e Hybrid Air-Plasm

a Spray/EB

-PVD Turbine C

ombustor EB

C System

s and Qualification

ND

2 N

D6

ND

7

Surface spallation

Tests •

Achieved low

thermal conductivity ranging from

1.0 -1.7 W

/m-K

•

Dem

onstrated high pressure environmental

stability at 2600-2650°F, 12-20 atm. in the high

pressure burner rig •

Surface recession or m

icro-spallation for less tougher coating system

s

2” diameter N

D3

EB

C/S

iC/S

iC

specimen after

testing in the high pressure burner rig A

t 2600°F+, 200 m

/s

High pressure burner rig tested new

ND

series Hybrid

EBC

systems coated on 2” diam

eter Gen II P

repreg S

iC/S

iC C

MC

s 16

Erosion and Impact A

spects: Early Mach 0.3 B

allistic Im

pact Tests of HfO

2 -Si Bond C

oat EBC

Systems

─

Advanced high toughness E

BC

s tested with com

parable performance of best TB

Cs

ND

2 ─

M

ore advanced EB

C com

positions currently also in developments

Spalled area, cm2

Projectile velocity, m/s

150 200 250 300 350

400 450

1.6 7Y

SZ and low k TB

Cs ZrR

ETT A

TES series N

D2

ND

3N

D6

ND

7SU

P-ERA

7.4 EBC

t'-ZrO

2/NA

SA EB

C

Cubic low

k ZrO2 k-N

ASA

EBC

500

NA

SA SU

P-ERA

7.4 EBC

ND

6 NA

SA EB

C

t'/ NA

SA EB

CN

D7 N

ASA

EBC Spalled

ND

3

ND

6 EBC

ND

7 EBC

1.4

1.2

1.0

0.8

0.6

ND

3

ND

6

SUP7.1A

EBC

0.4

0.2 SU

P-ERA

7.4 0.00.0

0.5 1.0

1.5 2.0

2.5 Energy, J

SUP-ER

A 7.4 EB

C N

D7

17

Advanced EB

C C

oating Material Strength Evaluations

– H

igh strength EB

Cs and bond coats are critical for prim

e-reliant designs •

Multicom

ponent EB

Cs and first-generation H

fO2 -S

i bond coat achieved 150-200 MP

a strength at high tem

perature (1400°C+)

• M

ulticomponent silicates show

ed improved high tem

perature strengths compared to

baseline yttrium and ytterbium

silicates •

High strength and high toughness are critical for erosion and fatigue cracking

669-Yb

2 Si 2 O 7

660-Y 2 Si2 O

7

659-Yb

2 SiO5

Strength, MPa

resistance 350

300

250

200

646-Specially toughened t' like HfO

2 648-EB

C B

ond Coat C

onstituent 658-A

E9932 660-Y

2Si2O7

657-Zr-RE silicate (M

ulti-component)

669-Yb2Si2O

7 670-R

are Earth Disilicate (M

ulti-component)

681-HfO

2-Si 696-EB

C B

ond Coat C

onstituent 150

100

500 0 200

400 600

800 1000

1200 1400

1600 Tem

perature, °CFlexure strengths of selected E

BC

materials

18

High H

eat Flux and CM

AS Resistance are Ensured by Advanced

High M

elting Point Coating, and M

ulti-Com

ponent Com

positions –

Non stoichiom

etric characteristics of the CM

AS

– rare earth silicate reacted apatite phases – up to 200 h testing

– D

ifference in partitioning of ytterbium vs. yttrium

in apatite •

Average AE

O/R

E2 O

3 ratio ~ 0.68 for ytterbium silicate – C

MA

S system

•

Average AE

O/R

E2 O

3 ratio ~ 0.22 for yttrium silicate – C

MA

S system

Ahlborg and Zhu, Surface &

Coatings Technology 237 (2013) 79–87.

RE

2 O3

SiO2

AEO

Com

position in apatite (100 hr):

Yttrium

Silicate EBC

Com

position in apatite (100 hr):

Ytterbium

Silicate EBC

19

High H

eat Flux and CM

AS Resistance Tests of Advanced EB

C

Systems

– M

ulticomponent rare earth silicate E

BC

showed im

proved performance

– S

ilicate based coatings still sensitive to CM

AS

concentrations (estimated

variation between average C

MA

S at 25 m

g/cm2 to m

ore concentrated region C

MA

S at 75 m

g/cm2)

– S

ome coating dam

age occurred for EB

Cs in JE

TS tests at higher C

MA

S loading

regions

Initially infiltrated /

Temperature, C

25h / 50h

100h 4450 Cycles

2000 C

MA

S tempertaure

Tsurface, C

Tback, C

1500

1000

500

Turbine vane EB

C, C

MA

S JE

TS

0 0 50

100 150

tests (100 h) Tim

e, hours

Laser rig test of advanced coating systems

20

Thermal G

radient Tensile Creep R

upture Testing of Advanced Turbine Environm

ental Barrier C

oating SiC/SiC

CM

Cs

─

Advanced high stability m

ulti-component hafnia-rare earth silicate based turbine

environmental barrier coatings being successfully tested for 1000 hr creep rupture

─

EB

C-C

MC

creep, fatigue and environmental interaction is being em

phasized

EB

C coated tensile specim

en

Laser beam

delivery optic system

C

ooling show

er head

Total strain, %

1.5 G

en II CMC w

ith advanced EBC Tested at 15 ksi &

heat flux Tsurface = 2700°F

Gen II CM

C-uncoated Tinterface= 2500°F

1.0 2400 F

TCMC back=2320°F

Tested at 20 ksi, 1316°C Typical prem

ature failure

Gen II CM

C with advanced EBC

tested 20 ksi, 1316°C 2400 F

0.5 G

en II CMC w

ith advanced EBC Tested at 20 ksi &

heat fluxjets

Tsurface = 2750ºF G

en II CMC uncoated

Tinterface = 2450ºF H

igh tem

perature 2400 F

Tested at 15 ksi, 1316°CTCM

C back = 2250ºC2250 F

0.0 1

extensometer

0 200

400 600

800 1000

1200Test specim

en Tim

e, hours

21

Thermal G

radient Fatigue-Creep Testing of A

dvanced Turbine Environm

ental Barrier C

oating SiC/SiC

CM

Cs -

Continued

Advanced environm

ental barrier coatings – Prepreg C

MC

systems dem

onstrated long-term

EB

C-C

MC

system creep rupture capability at stress level up to 20 ksi at T

EBC 2700°F, T

CM

C

interface ~2500°F

The HfO

2 -Si based bond coat show

ed excellent durability in the long term creep tests

EBC

s on Gen II C

MC

after 1000 h fatigue H

ybrid EBC

s on Gen II C

MC

after 1000 h testing

low cycle creep fatigue testing

22

High H

eat Flux Thermom

echanical fatigue Tests of A

dvanced NA

SA EB

C-B

ond Coats System

s on CM

Cs

• Laser H

igh Heat Flux them

omechanical fatigue testing of a H

fO2 -S

i and NA

SA

advanced E

BC

baseline with steam

at 3 Hz, 2600-2700°F, and 69 M

Pa m

aximum

stress with stress

ratio 0.05, completed 500 h testing

• Tsurface = 1500-1600°C

•

T= 1320-1350°C

• H

eat Flux = 170 W/cm

2 3 hz fatigue testing at 10 ksi loading C

ompleted 500 hr testing

Testing proving vital failure m

echanisms in a sim

ulated test environm

ents

• S

pecimen had som

e degradations

EBC

s

EBC

s H

igher Si content HfO

2 -Si

2323

EBC

-CM

C Therm

al Gradient C

reep Rupture and

Delam

ination Modeling

A

n equivalent stress model is established for E

BC

multicrack stress intensity m

odeling: em

phasize creep, thermal gradient and stress rupture interactions

D. Zhu and L. G

hosn, “Creep, Fatigue and Fracture B

ehavior of Environmental B

arrier Coating and SiC

-SiC C

eramic M

atrix Com

posite Systems: The R

ole of Environment Effects”, in

The 11th International C

onference on Ceram

ic Materials and C

omponents for E

nergy and Environm

ental Applications, V

ancouver, British C

olumbia, C

anada, June 15-19, 2015.

B

enchmark failure m

odes established in EB

C system

s, strong bond coat beneficial

Finite Elem

ent Analysis (FE

A) M

odeling

24

EBC

-CM

C Therm

al Gradient C

reep Rupture and

Delam

ination Modeling – B

ond Coat Stiffness Effect

─ A

dvanced EB

Cs designed w

ith higher strength and stiffness to improve

creep, fatigue, and cyclic durability

D. Zhu and L. G

hosn, “The Developm

ent of Environmental B

arrier Coating System

s for SiC-SiC

Ceram

ic Matrix C

omposites: Environm

ent Effects on the Creep and Fatigue R

esistance”, in A

erospace Coatings C

onference & E

xposition 2014: Developm

ent and Manufacturing T

rend for the 21st Century, H

artford, CT, U

SA, O

ctober 8, 2014

25

Fatigue Tests of Advanced RESi B

ond Coats and EB

C System

s -

AP

S and P

VD

processed 2700°F bond coats on CM

C: focus on fatigue testing at

temperatures 2400-2700°F

-E

BC

bond coats critical to prime-reliant coating system

designs Fatigue Tested

002_#17A

ir Plasm

a Sprayed A

PS

YSi+H

f-RE

Silicate 1316°C

, 10ksi, 1000 h fatigue (3 Hz, R

=0.05)

1169 h fatigue (3 Hz, R

=0.05) on GE

E

B-P

VD

HfR

E2 S

i2-x O7-x E

BC

/GdYbS

i(O) bond

Prepreg S

iC/S

iCcoat on C

VI-M

I SiC

/SiC

(with C

MA

S)

1537°C, 10ksi, 300 h fatigue (3 H

z, R=0.05)

EB

-PV

D R

E2 S

i2-x O7-x E

BC

/HfO

2 -Si bond coat on 3D

C

VI+PIP

SiC

/SiC

1482°C, 10ksi, S

PLC

F fatigue at 3 H

z, R=0.5 (300 h furnace tested, 500 h in laser

thermal gradient

Creep and Fatigue Test w

ith CM

AS

PV

D G

dYSi(O

) coated on Hyper Them

12C-461-

PV

D G

dYbSi(O

) bond coat,1316°C, 15ksi,

EB

C B

ond Coat series on R

oyce Royce H

TC

CV

I-MI S

iC/S

iC (w

ith CM

AS

) 1400°C

,at 10 ksi, 400 h

26

EBC

-CM

C Turbine Elem

ent Fatigue Testing

• Testing approaches developed for E

BC

-CM

C trailing edge therm

omechanical testing

• H

igh heat flux capability to simulate required high therm

al gradients and more com

plextem

perature distributions in a turbine engine•

Mechanical loading to sim

ulate the high pressure turbine airfoil pressure (ballooning) effects•

EB

C-C

MC

durability being evaluated, planned incorporation of stream jet environm

ents

Maxim

um P

rincipal Strain vs. A

irfoil Internal Pressure

EB

C coated Trailing E

dge (TE)

“wedge” testing in high heat flux and

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

0.22

0.24

0.26

0.28

0.30

0 20

40 60

80 100

120 140

160 180

Maxium Principal Strain (%)

Internal Pressure (psi)

mechanical fatigue loading

Modeled testing /

27

Strains Measurem

ents for Coated A

irfoil Trailing Edge Subelem

ents at High Loads

-The results show

ed complex coating cycling behavior, and out of phase strain cycles

also on the EB

C coated sides

-P

ossibly changed neutral axes of the deflections of the CM

C thin and thick w

alls -

Challenges for m

odeling along with therm

al in-phase and out-phase loading

28

Load, N

SiC/SiC

Turbine Airfoil Trailing Edge Tests

-S

ubelement w

edge testing and high temperature tests, aim

ing at understanding the C

MC

and EB

C degradation

MI S

iC/S

iC C

MC

2000

TEST_HT

DAM

AGE m

odel TEST_H

T

00.00 0.05

0.10 0.15

0.20 0.25

0.30 0.35

Displacements, m

m

4000

5000

6000

7000

8000

9000

TEST DAM

AGE m

odel

Von Mises

Stress Plot

4000 CV

I SiC

/SiC

CM

C

30003000

Load, N

No reduction 2000

1000 Subelem

ent Load-Displacem

ent curve – P

repreg MI C

MC

trailing edge

0-0.1 -0.1 0.0 0.1 0.1 0.2 0.2 0.3 0.3 0.4 0.4 0.4 0.5 0.5 0.6

Displacem

ents, mm

A

dvanced EB

C coated vanes tests

Subelem

ent Load-Displacem

ent curve – CV

I CM

C trailing edge

29

1000

Summ

ary •

Prime-R

eliant and durable EBC

s are critical to emerging SiC

/SiC C

MC

Hot-Section

component technologies

─

The EB

C developm

ent built on a solid foundation from past experience, evolved w

ith the current state of the art com

positions with higher tem

perature capabilities and stabilities •

Multicom

ponent EB

C oxide-doped silicates show

ed promise w

ith improved

stabilities, strength and toughness, and durability in various tests •

HfO

2 -Si and R

E-S

i bond coats, along with R

ES

iHfC

N potentially for realizing prim

e-reliant E

BC

-designs •

Advanced testing help scale-up for com

ponents and EV

C-C

MC

modeling

Current em

phases and future paths: ─

B

etter understanding of the coating failure mechanism

s, and helping develop coating property databases and validate life m

odels, aiming at m

ore robust EB

C-C

MC

designs ─

C

ontinue to focus on coating composition and processing im

provements, sim

ulated engine environm

ent testing and performance m

odeling ─

D

esign high strength, strain tolerant, CM

AS

resistant top coat; and dense, low diffusion

and high toughness EB

C and bond coats

─

Self-repairing and/or self-grow

ing of slow grow

th adherent EB

C coatings, m

inimizing

silica separation

30

A

cknowledgem

ents •

The work w

as supported by NASA

Fundamental Aeronautics Program

(FAP) Transform

ational Tools and Technologies (TTT) Project

In particular, the contributions from the follow

ing:

NA

SA

EBC-C

MC

Team, In particular, Jim

DiC

arlo, Jim Sm

ialek, Dennis Fox, Bryan H

arder, Robert A

. Miller,

Janet Hurst, M

artha Jaskowiak, R

am B

hatt, Mike H

albig, Valerie Wiesner, N

ate Jacobson, Narottam

B

ansal, Francisco Sola-Lopez, and S

erene Farmer, (N

AS

A G

RC

)

Collaborators include:

Sulzer M

etco (US

) -Mitch D

orfman; C

his Dam

bra D

irected Vapor Technologies, International – Derek H

ass and Balvinder G

ogia P

raxair Surface Technologies – John A

nderson and Li Li S

outhwest R

esearch Institute – Ronghua W

ei (PV

D coating processing)

in supporting the coating processing

31