Effects of Different Braze Materials and Composite Substrates on Composite/Ti Joints G.N. Morscher, M. Singh, R. Asthana, and T. Shpargel An ever increasing number of applications require robust joining technologies of dissimilar materials. In this study, three types of ceramic composites (C-C, C-SiC, and SiC-SiC) were vacuum brazed to commercially pure Ti using the Cusil-ABA (63 Ag – 35.5 Cu – 1.75 Ti) active metal braze alloy. The study also compared composite specimens as-fabricated and after surface grinding/polishing. A butt-strap tensile shear strength test was used to evaluate the joined structures at room temperature, 270 and 500 oC. The elevated temperatures represent possible use temperatures for some heat rejection type applications. Joint strength will be discussed in light of braze wetting and spreading properties, composite properties, and test temperature. 31st International Cocoa Beach Conference and Exposition Advanced Ceramics and Composites; January 21-26, 2007; American Ceramic Society; Daytona Beach FL

https://ntrs.nasa.gov/search.jsp?R=20070010537 2018-08-21T00:29:59+00:00Z

1

Nat

iona

l Aer

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tics

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e Ad

min

istra

tion

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asa.

gov

Effe

cts

of D

iffer

ent B

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Mat

eria

ls a

nd

Com

posi

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rate

s on

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posi

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nts

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gory

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ce In

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te; N

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h C

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at S

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tion

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gov

Bac

kgro

und

•A

pplic

atio

n: H

eat r

ejec

tion

syst

ems

requ

iring

C/C

fa

cesh

eets

join

ed to

Ti t

ubes

(Pro

met

heus

Pro

gram

)–

Tem

pera

ture

s ra

nge

from

-100

to 3

00o C

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sues

: –

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mal

exp

ansi

on m

ism

atch

bet

wee

n C

/C (-

1x10

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) and

Ti

(8.6

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nd h

igh

braz

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re (u

p to

100

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prea

ding

and

bon

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to c

ompo

site

su

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te–

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rent

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wea

knes

s of

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posi

te s

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rate

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test

s to

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e jo

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3

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istra

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gov

Our

App

roac

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site

and

det

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ine

effe

ct

of d

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ent b

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s an

d a

sold

er o

n jo

inin

g C

/C to

Ti

–Tu

be te

sts

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stra

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nsile

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ar te

sts

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stre

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ile a

nd

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4

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Spac

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min

istra

tion

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asa.

gov

Effe

ct o

f Bra

ze o

n C

/C to

Ti J

oint

s

5

Nat

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l Aer

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tics

and

Spac

e Ad

min

istra

tion

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w.n

asa.

gov

Exp

erim

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l: M

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p., S

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#

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Earli

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udy

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uate

d hi

gher

te

mpe

ratu

re

braz

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; Ti

CuN

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CuS

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and

low

er

cond

uctiv

ity C

/C;

Mat

er. S

ci. E

ng. A

., 41

8, 1

9-24

(200

6)

6

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and

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istra

tion

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gov

Exp

erim

enta

l: Te

st T

echn

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s an

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peci

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bra

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UR

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bra

ze s

prea

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ON

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A–

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ther

mal

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CK

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k

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ater

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Load

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mm

C/C

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ube

Rig

id

Bloc

k

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e M

ater

ial

Appl

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Load

12.6

mm

Tube

-Pla

te T

ensi

le T

est

But

t-Stra

p Te

nsile

(BST

) Sh

ear T

est

7

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34.2

41.1

18.7

49.7

13.5

8.2

010203040506070

TiCuSil Foil

TiCuSilPaste

Cusil-ABAFoil

Cusil-ABAPaste

Cusin-1ABAFoil

Incusil ABAFoil

Failure Load, N

Tube

-Pla

te T

ensi

le T

est

•C

usil-

AB

A, f

ollo

wed

by

TiC

uSil,

ha

d hi

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t loa

d-ca

rryi

ng a

bilit

y an

d la

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ded

area

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usin

-1A

BA

and

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silA

BA

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lo

wes

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ng a

bilit

y an

d po

or b

raze

spr

eadi

ng•

Tens

ile “

Stre

ngth

”ap

prox

. 0.5

MPa

•P1

20 C

/C (C

VI) b

raze

d to

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s st

rong

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an T

300

C/C

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in-

deriv

ed) b

raze

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Ti (

TiC

uSil

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load

~ 9

N) o

f ear

lier s

tudy

10 m

m

Incu

sil

CuS

il-A

BA

C/C

com

posi

te

Ti T

ube

Rig

id

Bloc

k

Braz

e M

ater

ial

Appl

ied

Load

12.6

mm

C/C

com

posi

te

Ti T

ube

Rig

id

Bloc

k

Braz

e M

ater

ial

Appl

ied

Load

12.6

mm

8

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iona

l Aer

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tics

and

Spac

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min

istra

tion

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gov

Tube

-Pla

te T

ensi

le T

est

ΔαΔ

TC

rack

s

•A

ll br

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m5

mm

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ck

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ube

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ater

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12.6

mm

C/C

com

posi

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Ti T

ube

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id

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e M

ater

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12.6

mm

TiC

uSil

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-fab

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9

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But

t-Stra

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ar T

est

•S

olde

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ulte

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sig

nific

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hig

her s

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an

braz

es fo

r Ti t

o C

/C•

C/C

bra

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to C

/C e

xhib

ited

high

she

ar s

treng

th a

s w

ell

0.90

0.80

0.49

1.51

7.61

8.21

012345678910

TiCuSil ABAFoil

TiCuSil ABAPaste

CuSil ABAFoil

CuSil ABAPaste

S BondSolder

C/C to C/Cw/CuSilABA

Paste

Shear Strength, MPa

10

Nat

iona

l Aer

onau

tics

and

Spac

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min

istra

tion

ww

w.n

asa.

gov

0.90

0.80

0.49

1.51

7.61

8.21

012345678910

TiCuSil ABAFoil

TiCuSil ABAPaste

CuSil ABAFoil

CuSil ABAPaste

S BondSolder

C/C to C/Cw/CuSilABA

Paste

Shear Strength, MPaB

utt-S

trap

Tens

ile S

hear

Tes

t

•P

re-e

xist

ing

crac

ks in

C

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r bra

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spec

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s du

e to

ΔαΔ

T

No

pre-

exis

ting

crac

ks

obse

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in S

Bon

d or

br

azed

C/C

to C

/C

11

Nat

iona

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and

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tion

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Effe

ct o

f ΔαΔ

T(E

stim

ated

) on

She

ar S

treng

th•

Ass

umes

ela

stic

beh

avio

r, C

TE(T

i) =

8.6x

10-6

/C; C

TE (C

/C) =

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0-6 /C

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nly

braz

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nd s

olde

r whi

ch s

how

ed fu

ll sp

read

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e co

mpa

red

0123456789

00.

20.

40.

60.

81

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T, %

BST Shear Strength, MPa

C/C

to C

/C (C

uSil

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ond

Sol

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CuS

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shea

r stre

ngth

ap

prox

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ely

15 M

Pa

CuS

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BA

sele

cted

as

“bes

t bra

ze”

beca

use

sold

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eltin

g te

mpe

ratu

re (~

410

C)

too

low

com

pare

d to

ap

plic

atio

n te

mpe

ratu

re

(~ 3

00C

)

12

Nat

iona

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tics

and

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min

istra

tion

ww

w.n

asa.

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Effe

ct o

f Com

posi

te S

ubst

rate

Whe

n U

sing

C

uSil-

AB

A P

aste

as

Bra

ze(fo

r oth

er a

pplic

atio

ns)

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t-Stra

p Te

nsile

She

ar T

ests

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iC =

T30

0 re

info

rced

CV

I SiC

SiC

/SiC

= S

ylra

mic

rein

forc

ed M

elt-I

nfilt

rate

d S

iC

13

Nat

iona

l Aer

onau

tics

and

Spac

e Ad

min

istra

tion

ww

w.n

asa.

gov

BS

T S

hear

Stre

ss a

t Roo

m a

nd 2

70o C

1.51

1.40

1.54

1.88

8.77

10.4

9

0.00

2.00

4.00

6.00

8.00

10.0

0

12.0

0

14.0

0

16.0

0

18.0

0

C/C (RT)

C/C (270C)

C/SiC (RT)

C/SiC (270C)

SiC/SiC (RT)

SiC/SiC(270C)

Stress, MPa

Circ

les

= as

-pro

duce

d su

rface

Squa

res

= gr

ound

sur

face

No

diffe

renc

e in

av

erag

e va

lues

fo

r as-

prod

uced

an

d gr

ound

su

rfac

es

14

Nat

iona

l Aer

onau

tics

and

Spac

e Ad

min

istra

tion

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w.n

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gov

Ther

mal

ly-In

duce

d C

rack

ing

in C

ompo

site

Con

trol

s

Sh

ear S

tren

gth

of B

raze

d Jo

ints

Cra

ck in

out

er

ply

of S

iC/S

iCC

rack

in o

uter

pl

y of

C/S

iC

TiTi-- C

/C C

ompo

site

C/C

Com

posi

te

TiTi-- C

/SiC

Com

posi

teC

/SiC

Com

posi

teTiTi

-- SiC

/SiC

Com

posi

teSi

C/S

iC C

ompo

site

Inte

rlam

inar

shea

r str

engt

h C

/C ≅

10-1

5 M

PaC

/SiC

≅15

-25

MPa

SiC

/SiC

≅35

-45

MPa

τ xy≅

1.5

MPa

τ xy≅

1.7

MPa

τ xy≅

10 M

Pa

15

Nat

iona

l Aer

onau

tics

and

Spac

e Ad

min

istra

tion

ww

w.n

asa.

gov

Use

of H

TPO

CO

Foa

m a

s S

addl

e M

ater

ial:

C/C

–H

TPC

O –

Ti tu

be M

ultil

ayer

Stru

ctur

es

Cu-

Sil

AB

A p

aste

use

d to

bra

ze e

ach

join

t

16

Nat

iona

l Aer

onau

tics

and

Spac

e Ad

min

istra

tion

ww

w.n

asa.

gov

Poc

oFo

am S

truct

ures

with

C/C

Fac

eshe

et

Diff

eren

t tub

e-Po

coco

ntac

t are

as fa

bric

ated

in o

rder

to

var

y co

ntac

t are

a an

d st

ress

app

lied

to b

raze

join

t.

Tube

on

flat

Tube

in s

hallo

w

trou

ghTu

be in

dee

p tr

ough

Test

ed in

tens

ion

and

shea

r:

Hig

hest

con

tact

ar

ea, l

owes

t st

ress

on

join

t

Low

est c

onta

ct

area

, hig

hest

st

ress

on

join

t

17

Nat

iona

l Aer

onau

tics

and

Spac

e Ad

min

istra

tion

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•EX

CEL

LEN

T A

DH

ESIO

N O

F B

RA

ZE T

O F

OA

M A

ND

Ti

TUB

E. F

AIL

UR

E A

LWA

YS O

CC

UR

RED

IN P

OC

O.

Star

t of

Poco

failu

re in

be

ndin

g

Deb

ond

Deb

ond

in o

uter

ply

in

out

er p

ly

of C

/Cof

C/C

Afte

r she

arA

fter T

ensi

on

Poc

oFo

am S

andw

ich

Stru

ctur

es w

ith W

oven

K11

00

and/

or W

oven

P12

0 C

/C F

aces

heet

Max

imum

shea

r str

esse

ssub

ject

ed to

br

aze

exce

eded

12

MPa

base

d on

load

ap

plie

d an

d ap

prox

imat

e br

aze

area

.

Max

imum

tens

ile st

ress

essu

bjec

ted

to

braz

e ex

ceed

ed 7

MPa

base

d on

load

ap

plie

d an

d ap

prox

imat

e br

aze

area

.

18

Nat

iona

l Aer

onau

tics

and

Spac

e Ad

min

istra

tion

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gov

Con

clus

ions

•C

/C c

ompo

site

s co

uld

be b

raze

d to

Ti p

late

s or

tube

s, th

e pa

ste

form

of

Cus

il-A

BA

pro

vidi

ng th

e be

st p

erfo

rman

ce o

f the

bra

ze m

ater

ials

stu

died

he

re•

Bra

ze/S

olde

r bon

ding

& s

prea

ding

to C

/C a

nd p

roce

ssin

g te

mpe

ratu

re

(ther

mal

ly-in

duce

d st

rain

) are

stro

nges

t fac

tors

con

trolli

ng jo

int s

treng

th–

S B

ond

sold

er o

utpe

rform

ed a

ll br

azes

due

to lo

wer

pro

cess

ing

tem

pera

ture

–cr

acks

wer

e fo

rmed

in b

raze

and

C/C

for a

ll of

the

braz

ed jo

int s

peci

men

s,

but w

ere

not f

orm

ed in

the

S B

ond

sold

er s

peci

men

–C

usil-

AB

A (p

aste

form

) out

perfo

rmed

all

braz

es b

ecau

se it

was

the

low

est

proc

essi

ng te

mpe

ratu

re b

raze

of a

ll th

e br

azes

whi

ch fu

lly s

prea

d an

d bo

nded

to

C/C

•Th

e hi

gher

con

duct

ivity

P12

0 C

VI C

/C a

ppea

rs to

ena

ble

stro

nger

join

ts

com

pare

d to

the

T300

Res

in-D

eriv

ed C

/C te

sted

in th

e ea

rlier

stu

dy•

SiC

/SiC

com

posi

tes

had

high

er jo

int s

treng

ths

than

C/C

or C

/SiC

,pr

esum

ably

bec

ause

the

inte

rlam

inar

she

ar s

treng

th o

f SiC

/SiC

isgr

eate

r tha

n th

e ot

her c

ompo

site

s•

The

Poc

oFo

am is

the

wea

k lin

k in

the

tube

-foam

stru

ctur

es a

nd n

ot th

e br

azed

join

t. Fa

ilure

in te

nsio

n an

d sh

ear a

lway

s oc

curs

in th

e fo

am

whe

ther

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osu

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e bo

nd a

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or a

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ss in

the

join

t.