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MÖSSBAUER STUDIES OF ELECTROFORMED MATERIALS
H. Leidheiser, Jr, A. Vértes, I. Czakó-Nagy, M. Varsányi
To cite this version:
H. Leidheiser, Jr, A. Vértes, I. Czakó-Nagy, M. Varsányi. MÖSSBAUER STUDIES OF ELEC- TROFORMED MATERIALS. Journal de Physique Colloques, 1980, 41 (C1), pp.C1-351-C1-352.
�10.1051/jphyscol:19801131�. �jpa-00219615�
JOURNAL DE PHYSIQUE
Colloque
Cl, suppl6ment au n "
1,Tome
41,janvier
1980,page
C1-351M~SSBAUER STUDIES OF ELECTR0FOPS"IED W E R I A L S
H. Leidheiser, Jr., A. VBrtes, I. czakS-~agy and K. varshnyi
Center for Surface and Coatings Research, Lehigh University, Bethlehem, PA, U.S.A. and I n s t i t u t e o f Physical Chemistry and Radiology, Lorand Eb'tvBs University, Budapest, Hungary.
ABSTRACT
During t h e p a s t few years a cooperative program o f research on t h e a p p l i c a t i o n o f M'dssbauer Spectro- scopy (MS) has been c a r r i e d o u t among i n v e s t i g a t o r s a t Lorand EatvSs Univ. and a t Lehigh ~ n i v . ' - ~ This r e p o r t represents a sumnary o f research concerned w i t h 4 d i f f e r e n t types o f electroformed m a t e r i a l s .
Chenical S t a t e o f Cobalt i n Cobalt-Hardened Gold Electrodeposi t s . Gold e l ectrodeposi t s , co- deposited w i t h c o b a l t , have wide a p p l i c a b i l i t y i n t h e e l e c t r o n i c s i n d u s t r y i n p r o t e c t i n g c u b s t r a t e s from c o r r o s i o n because t h e y have s a t i s f a c t o r y con- t a c t r e s i s t a n c e s and e x h i b i t s e r v i c e a b l e wear r e -
~ i s t a n c e . ~ A1 though these deposits a r e e x t e n s i v e l y used, t h e chemical n a t u r e o f the c o b a l t i n t h e g o l d
The main component i s m e t a l l i c c o b a l t (6 = -0.6 t o -0.7 w / s ) i n s u b s t i t u t i o n a l s i t e s i n t h e g o l d l a t - t i c e . Minor components are i n t e r p r e t e d t o be B-CoOOH, presumably brought t o t h e cathode i n c o l - l o i d a l form a f t e r formation a t t h e anode, and an i o n i c c o b a l t species complexed i n d i f f e r e n t ways depending upon t h e c a n p o s i t i o n of t h e p l a t i n g bath.
I
Id e p o s i t was n o t known. We have addressed t h i s C problem u s i n g 5 7 ~ o emission MS. A previous stuhy Z
8
i n which t h e emission spectra o f a l a r g e number o f 2 $ I C
c o b a l t oxides and c o b a l t oxyhydroxides had been de- Z 4
6 LL
termined provided an e x c e l l e n t background f o r C
a;
t h i s work. The f a c t t h a t cobalt-hardened g o l d y c
2 e l e c t r o d e p o s i t s c o n t a i n s i g n i f i c a n t amounts of C, LL
7 P 2
0, N, and
H
and t h a t n u n - m e t a l l i c i n c l u s i o n s have Cbeen observed i n transmission e l e c t r o n microscopy 8 provided a d d i t i o n a l s t i m u l u s t o perform such s t u d i e s .
Deposits were formed from 3 d i f f e r e n t commer- c i a l baths i n which t h e c o b a l t was i n t h e form o f a c h e l a t e o r a s u l f a t e . Small amounts o f 5 7 ~ o were added t o each b a t h and commercial p l a t i n g condi- t i o n s were u t i l i z e d . A b r o a d peak i n t h e emission spectrum was observed s h o r t l y a f t e r d e p o s i t i o n and values o f
I'
i n t h e range o f 1.3-1.6 mn/s which de- creased t o 0.9-1.1 mm/s a f t e r aging f o r 10-35 days.These l a r g e changes i n d i c a t e t h a t many o f t h e co- b a l t atoms a r e i.n metastable s i t e s and rearrange- ments i n c r y s t a l l o g r e p h i c s i t e o r chemical m v b i n a - t i o n t a k e p l a c e w i t h time.
A t y p i c a l spectrum o f cobalt-hardened g o l d e l e c t r o d e p o s i t agec! f o r 10 days i s shown i n Fig. 1.
Fig. 1. Spectrum o f Co-hardened Au d e p o s i t a f t e r aging f o r 10 days a f t e r d e p o s i t l c n .
E l e c t r o d e p o s i t e d T i n - N i c k e l A l l o y s . The t i n - n i c k e l system i s o f i n t e r e s t because t h e s t o i c h i o - m e t r i c a l l o y NiSn i s used i n t h e e l e c t r o d e p o s i t e d form t o p r o t e c t e l e c t r o n i c canponents from c o r r o - sion. Sn-Ni a1 lo y s of a range of c a n p o s i t i o n s were p l a t e d on copper s u b s t r a t e s from t h e f l u o r i d e b a t h o f Cuthbertson e t a1 a t a temperature o f 65°C and 9 a c.d. o f 5 mA/m 2
.
A t y p i c a l spectrum o f a Sn-Ni a l l o y e-lectro- d e p o s i t c o n t a i n i n g more than 50 d t % Sn i s shown i n F i g u r e 2. The s p e c t r a were i n t e r p r e t e d i n terms of 3 components on t h e b a s i s o f a l l d a t a c o l l e c t e d
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19801131
C1-352 JOURNAL DE PHYSIQUE
s.nd i n f o r m a t i o n i n t h e l i t e r a t u r e : a d o u b l e t w i t h 6 = 1.8 m / s was a t t r i b u t e d t o NiSn; a s i n g l e t w i t h 6 = 2.5 m / s was a t t r i b u t e d t o elemental Sn; a sing- l e t w i t h 6 = 1.5-1.8 mn/s was a t t r i b u t e d t o a Cu-Sn a l l o y . T h i s l a t t e r l i n e was present when pure t i n was e l e c t r o d e p o s i t e d on copper and was absent i n samples i n which t h e d e p o s i t was s t o i c h i o m e t r i c NiSn. A s i g n i f i c a n t increase i n t h e Cu-Sn a l l o y was observed when Sn-rich deposits were heated a t 300°C.
The absence o f evidence f o r any Cu-Sn compound when s t o i c h i o m e t r i c Yi-Sn i s e l e c t r o d e p o s i t e d on copper i s i n accord w i t h t h e f i n d i n g s o f Smart and Robins. 10
Fig. 2. Spectrum o f t i n - r i c h Sn-Ni e l e c t r o d e p o s i t . The s i m i l a r i t y o f s p e c t r a i n b o t h t h e absorp- t i o n and emission modes suggests homogeneity of t h e deposit.
Passive F i l m Formed on T i n i n Borate B u f f e r . MS i s a s u i t a b l e technique f o r s t u d y i n g t h e passive f i l m formed on t i n d u r i n g anodic treatment i n b o r a t e b u f f e r . S a t i s f a c t o r y s p e c t r a (Fig. 3) were obtained a t 78°K i n a b s o r p t i o n geometry u s i n g l a y e r s o f alu- minum f o i l on which t i n enriched i n '19sn had been e l e c t r o d e p o s i t e d . I n s i t u emission s p e c t r a were ob- t a i n e d u s i n g 119m~n b u t t h e q u a l i t y o f t h e s p e c t r a was l i m i t e d by t h e low r a d i o a c t i v i t y o f t h e t h i n t i n e l e c t r o d e p o s i t used as t h e source. The anodic o x i d e formed on t i n i n b o r a t e b u f f e r a t pH 8.5 i s r e s i s - t a n t t o a t t a c k by t h e e l e c t r o l y t e over a p o t e n t i a l range of -500 t o -1100 mV vs SCE. Some evidence was obtained t h a t suggested a low r a t e o f d i s s o l u t i o n d u r i n g p o l a r i z a t i o n a t -860 mV. The predominant species p r e s e n t i n t h e anodic o x i d e was t e t r a v a l e n t t i n over t h e e n t i r e p o t e n t i a l range, a1 though no conclusive statement can be made t h a t d i v a l e n t t i n does n o t e x i s t a t t h e l o w e r p o t e n t i a l s . I t was im- p o s s i b l e t o determine whether o r n o t t h e passive f i l m contained water o r hydroxyl ions.
I I I I I I I I
- 2 - 1 0 1 2 3 4
VELOCITY (mm/rl
Fig. 3. Spectrum o f a t i n sample p o l a r i z e d i n b o r a t e b u f f e r f o r 60 min a t +250 mV vs SCE.
anodic treatment o f CO(OH)~, deposited on a P t e l e c - trode, i n b o r a t e b u f f e r a t +6DO t o +900 mV vs SCE, was i d e n t i f i e d by i n s i t u MS measurements. A t Rt,
t h e spectrum c o n s i s t e d o f a s i n g l e l i n e w i t h 6 = +0.08 mm/sec (vs m e t a l l i c i r o n ) . Anodic
--
p o l a r i z a - t i o n o f a c o b a l t e l e c t r o d e ( c o n t a i n i n g "CO i n t h e surface) y i e l d e d a m i x t u r e o f 6-CoOOH and Coo2 as determined by emission spectroscopy. The c o b a l t s u b s t r a t e a p p a r e n t l y prevents t h e e x c l u s i v e forma- t i o n o f Coop. Exposure o f Coo2 t o a i r f o r 3 months r e s u l t e d i n decomposition t o Co304 as determined by emission spectroscopy.1 . Vgrtes, A., Leidheiser, H., Varsgnyi, M.L.,
Simmons, G.W., and Kiss, L., J. Electrochem.
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(1978) 1946.2. Simmons, G.W., V6rtes, A., VarsBnyi, M.L., and Leidheiser, H., J. Electrochem.
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(1979) 187.3. L e i d h e i s e r , H., Czak6-Nagy, I., Varsdnyi, M.L., and Vertes, A., J. Electrochem. Soc.
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(1979)204.
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(1979) 391.5. A n t l e r , M., i n "Gold P l a t i n g Technology", Reid, F.H., and Goldie, W., E d i t o r s , pp. 259-294, E l e c t r o c h e m i s t r y P u b l i c a t i o n s , Ltd., Ayr, Scot- l a n d (1974).
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" P a s s i v i t y and I t s Breakdown on I r o n and I r o n Base A l l o y s " , Staehle, R.W. and Okada, H., E d i t o r s , pp. 65-68, N a t l
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Assocn. Corrosion Engineers (1 976).7. Raub, C.J., KnZldler, A., and Lendvay, J., P l a t . S u r f . F i n i s h .
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(1976) 35.8. Okinaka, Y., and Nakahara, S., J . Electrochem.
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108 (1960).Anodically-Formed Coo2. Coo2, formed by
