Metallization of Polymers - American Chemical Society

Chapter 21

Aluminum—Polyester Corrosion An X-ray Photoelectron Spectroscopic Study 1

1

1

2

2

M. Chtaïb , Y. Novis , R. Caudano , P. Lutgen , and G. Feyder

Downloaded by MONASH UNIV on December 5, 2016 | http://pubs.acs.org Publication Date: November 9, 1990 | doi: 10.1021/bk-1990-0440.ch021

1

Facultés Universitaires Notre-Dame de la Paix, Laboratoire Interdisciplinaire de Spectroscopie Electronique, Rue de Bruxelles 61, B-5000 Namur, Belgium E. I. du Pont de Nemours and Company, Luxembourg 2

M e t a l l i z e d polymers are used nowadays i n numerous i n d u s t r i a l applications etc...). systems

(food

packaging,

The adhesion and the d u r a b i l i t y

magnetic

tapes

of metal/polymer

represent the most important concepts that concern

many research groups which

capacitors,

(1-3). Obviously, any aggressive medium

corrodes the metal f i l m

will

be d i r e c t l y

related to

some l o s s of adhesion and d u r a b i l i t y . The aim of t h i s work i s t o i n v e s t i g a t e the influence of corrosive environments on aluminum layers evaporated onto PET f i l m and e s p e c i a l l y on both the A l surface and i n t e r f a c e . M e t a l l i z e d Mylar® weeks

before

was soaked i n

the XPS

profiling.

bidistilled

water f o r three

A dry sample

was a l s o

analyzed f o r comparison purposes. The p r o f i l e of the t r e a t e d f i l m showed the growth of stoichiometric Al2O3 on the surface of the A l f i l m . Furthermore, a Mylar® NaCl

and d r i e d

f i l m was contaminated on purpose with

i n air before m e t a l l i z a t i o n .

XPS r e s u l t s

revealed a c l e a r chemical r e a c t i o n at the i n t e r f a c e between A l and NaCl. The growth of A l on NaCl c r y s t a l s was seen to be responsible f o r the appearance of a large number of p i n holes and cracks i n the samples.

0097-6156/90A)44a-0288$06.00/0 © 1990 American Chemical Society Sacher et al.; Metallization of Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990.

21.

289

Aluminum-Polyester Corrosion

CHTAIB ET AL.

Results

Water From

corrosion Fig. l

one

r

oxygen

and

soaked

i n water

is

a thin

Al

clearly

are

sees t h a t t h e XPS

drastically

(21 d a y s ) .

layer

of carbon

changed

At

the


-

first

The

oxide

second

contamination

(120

layer

one

(80 Â)

Â) has

has

50%

the

uppermost

surface,

both was

there

aluminum

composition.

4 0 % A l and Al

of

sample

above l a r g e

oxide c o n s i s t i n g of 3 l a y e r s of d i f f e r e n t - The

profiles

when

and

60% Ο

50%

AI2O3

:

: A10 (A10H

Ο

hydroxyde) -

The

third

diffusion

part

layer

(175

Â)

of

the

with d e f i c i e n t

Al

oxide

represents

oxygen c o m p o s i t i o n

: Al O x

a (y

y

s m a l l e r than x ) . By

o p p o s i t i o n t o the

a

much t h i n n e r o x i d e

Al -

treated layer

film, (native

oxide

of

«

3-dimensional spectra of F i g . 2 d i s p l a y The

metallic Since

peak

state

this

at

i s too

of

species

A10H.

like

low

b i n d i n g energy

while the

peak

convolution

Al^ +

broad wide,

peak

peak we

60 Â)

has

and

an

increase soaked

of

the

intrusion

into

hydroxyde

composition

NaCl

with

a

peak

at

I t appears

with

an

the

due

to

interface these

causes

accompanying

the

in

the

(AI2O3) .

feature a

other

oxide

confirm a

slight

f o r the

results

change

Al

to A l ^ +

for this

interface

from

A l n a t i v e oxide

and

peak

to

sample

that

water

A l to converts of

the

metal

to

film

morphology.

corrosion

Mylar®

before

oxide

i n water.

i s due

A 1 2 p core

the

i s due

invoke

- Spectra of A 1 2 p recorded at the

A

r e f e r e n c e sample

c o n c e n t r a t i o n i n the b u l k c l o s e t o 95% . The

level.

an

the

film

was

contaminated

metallization.

different microscope

areas were

of

XPS

these

also

with

profiles samples.

made

in

NaCl were

and

dried

carried

Observations

reflexion

and

by

in air out

in

optical

transmission

modes.

Sacher et al.; Metallization of Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990.


METALLIZATION OF POLYMERS


CHTAIB ET AL

Aluminum-Polyester Corrosion

Fig.

A12p c o r e l e v e l s v e r s u s e t c h i n g d e p t h Réf.sample, (b) wet sample

291


21.

2


(a)

292


The

XPS p r o f i l e s

the

NaCl

were

performed

contaminated

profiles

presented

contaminated compared

As

one

spots

visible in

can see from

i n F i g . 3. t h e A l s u r f a c e

sample

does

to the surface

drastic

on w h i t e

sample.

not present

o f t h e NaCl

major

differences

o f t h e r e f e r e n c e sample.

changes between t h e two samples

the

However,

are observed

at the

i n t e r f a c e and i n t h e b u l k o f A l : Firstly

: The A l c o n c e n t r a t i o n f a l l s


reference

sample

Also

a

large

this

latter

Secondly,

t o around

amount

from

98 a t o m i c

% i n the

80% i n t h e c o n t a m i n a t e d

o f oxygen

and carbon

sample.

are detected i n

sample. t h e CI s i g n a l

fingerprints

the presence

i n t h e second

profile

o f NaCl

. This

latter

picture

obtained

of F i g . 3 seems t o be

located at the interface.

The

optical

microscope

contaminated some a r e a s

sample e x h i b i t s o f t h e sample

profile

i n these

presence

o f t h e NaCl

two

pictures

(transmitted the f i l m . due

are

of

light)

were

from

matches

in reflection o f aluminum

reveals

and

t h e same

(transmitted

while the bright

t h e XPS the

i n F i g . 5 . The

light)

of the aluminized

o f NaCl

observed

crystals

F i g . 6b

region of light) i s

polyester

which

is

spots o f t h i s

picture

the locations

of the

mode takes

(Fig.6a) . This place

means

where

t h e NaCl

and sodium

chloride

are present.

PiSCUSSiQn

have

(NaCl)

obtained

NaCl

growth o f A l i n

shown

(reflected

side of the Fig.6b

the corrosion

between

the crater

to the A l cracks

crystals

oriented

the

When p e r f o r m i n g

the ion etching

inside

F i g . 6a

The d a r k

free

due

that

We

regions,

t o the region

almost

a well

(Fig.4).

from

âHd

studied

conclusion

the effect

on a l u m i n i z e d M y l a r . water

important

and b o t h

step

leading

o f water We

aluminum

suggest

that

and i t s n a t i v e

to the corrosion

the reaction oxide

i s an

of the metallic



21.

CHTAÏBETAL.

0

Aluminum—Polyester Corrosion

293

Sputter Time (seconds)

590

πβδ

Fig.

1

3

XPS p r o f i l e s o f A l , O, C and CI (a) R e f . sample, (b) c o n t a m i n a t e d sample


(NaCl)


294


Fig.

4

Fig.

5

Picture

Picture

of A l / M y l a r contaminated with NaCl

of NaCl c r i s t a l s

i n s i d e the

crater.


CHTAÏB ET AL.

Aluminum—Polyester Corrosion


21.

Fig.

6

P i c t u r e o f same c o n t a m i n a t e d a r e a , (a) r e f l e c t e d l i g h t , (b) t r a n s m i t t e d l i g h t .


295


296 film.

Even

barrier. oxide

though,

It

appeared

porosity

causes

the

Al

native oxide

that

the

moisture

comes i n c o n t a c t w i t h

i t s h y d r a t a t i o n by

provides

a reaction

protective

intrusion

the

via

the

aluminum m e t a l

and

of t h i s

type

(4)

2 A l + 4 H 2 O -> 2 A100H + 3 H 2 Î

On

the

other

aluminized


to

the

hand,

the

presence

polyester interface

appearance

of

pin-holes

can and

of

NaCl

react

contaminant

with

cracks

Al

and

i n the

in

leads

metallic

layer.

Acknowledgments

The

authors

Microscope

wish

to

analyses.

thank This

Programm RI,1B-0178 o f t h e

Literature

p r o f e s s o r P. work

is

Overlau

supported

by

for the

Optical BRITE

EEC.

cited

1. Industrial Adhesion Problems, ed. by D.M. Brews and D. Briggs, Chapter 4, Orbital Press, Oxford, 1985. 2. De Koven, B.M.; Hagano, P.L., Appl. Surf. S c i . 1986, 27, 199. 3. M i t t a l , K.L., J. Vac. S c i . Technol. 1976, 13, 19. 4. Venables, J.D.; J. Mat. S c i . 1984, 19, 2431-2453. RECEIVED May 16,

1990


Metallization of Polymers - American Chemical Society

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