Influence of a Magnetic Field on the Electrodeposition of Nickel-Iron Alloys

Influence of a Magnetic Field on the Electrodeposition of

Nickel-Iron Alloys

Adriana Ispas, Andreas Bund

SFB 609

2

Outline

Introduction Experimental details Results and discussions

Iron content vs. current density Iron content vs. magnetic field Hydrogen evolution Morphology aspects

3

Alloy Deposition: is the simultaneous deposition of more than one metal

Advantages: Most of the alloys can be deposited without much difficulties Most of the alloys have useful properties: finer grains, harder, stronger, more

corrosion resistant than the parent metals, high magnetic permeability

→ Because of that, in some applications the alloys replace the single metal

Disadvantage: Alloys deposition request close control of the electrolytic bath

Ni-Fe alloys present a high internal strength, hardness and special magnetic properties

Brenner: „Anomalous codeposition“ is characterized by the anomaly that the less noble metal deposits preferentially

Abner Brenner, Electrodeposition of Alloys. Principle and Practice, Vol.1 (1963), Academic Press New York and London, p.77

“Modern Electroplating”, fourth edition, edited by M. Schlesinger and M. Paunovic, John Wiley & Sons, INC., 2000, p. 468

4

Magnetic field influences

the properties of the deposited layers the transport of electroactive species

(MHD effect)

C2μ

BχF

0

2m

p

BvEqF

Force acting on the moving ions in the solution (Lorentz force):q= electric chargeE=electric fieldv= velocityB= magnetic field

0

m

μ

BBχCF

Paramagnetic force: Force due to B Gradient

m -the molar susceptibility

C –concentration -the vacuum permeability

5

Magnetic field effects

From: J. M. D. Coey, G. Hinds, Journal of Alloys and Compounds, 326(2001), 238-245.

• induces an additional convection in the electrolyte that decreases the thickness of the diffusion layer → increasing of the limiting current • increases the mass transport

Disk electrode

ΔV

B

I

F

6

Experimental details

QN C S

RE CE

WENA

L

Experimental set-up

N, S → poles of the electromagnetC → electrochemical cellQ → quartzWE → working electrode (Au)CE → counter electrode (Pt)RE → reference electrode (Ag/AgCl/KCl) NA → Network Analyzer

B

E

Orientation 1

B

E

Orientation 2

Composition of the bath: 0.5 M NiSO4*6H2O; 0.01 M FeSO4*7H2O; 0.4 M H3BO3 ; pH=2-3

0.5 M NiSO4*6H2O; 0.07 M FeSO4*7H20; 0.4 M H3BO3; pH=2

7

Quartz Crystal Microbalance

1/2 qq

20

ρμA

Δm2fΔf

quartz

gold electrodes

film

shear motion

Sauerbrey equation:

9,997 9,998 9,999 10,000

0

20

40

60

80

100

Quartz withRigid Layer

UnloadedQuartz

Quartz withDamping Layer

w0

wLayer 1

wLayer 2

fR,Layer 2

fR,Layer 1 fR,0

Rea

l Par

tof

Adm

ittan

ce /

mS

f / MHZ

2* w

iΔff

Mass Damping

Complex frequency shift

(μq = shear modulus [g/cm s2]; ρq = density of the quartz [g/cm3]; A =piezoelectrically active area)

8

Phase Diagram

From: Scientific Group Thermodata Europe Binary Phase Diagram Collection

9

Saturation flux density values

From: E.I. Cooper et al. , IBM J. Res. & Dev., vol. 49 (2005), no. 1, 103-126.

10

Iron content in Weight percent

-60 -50 -40 -30 -20

2

3

4

5

Fe

in

dep

osi

ted

allo

y/ W

t%

itotal

/ mA cm-2

B = 0 mT

Fe in the bath- 0.05 Wt%

1-st Electrolyte

Composition of the bath: 0.5 M NiSO4*6H2O; 0.01 M FeSO4*7H2O; 0.4 M H3BO3 ; pH=2-3

11

Influence of the B field on iron content

0 150 300 450 6000

1

2

3

4

Fe

co

nte

nt

/ W

t%

B / mT

itotal

= -35 mA cm-2

itotal

= -45 mA cm-2

itotal

= -50 mA cm-2

B E

B || E B E

0 100 200 300 400 500

2

3

4

5

Fe

cont

ent

/ W

t%

B / mT

itotal

= -35 mA cm-2

itotal

= -45 mA cm-2

itotal

= -50 mA cm-2

B E

12

The damping change of the quartz

0 50 100 150 200 250 300

-800

-400

0

400

800

1200D

ampi

ng c

hang

e,

w /

Hz

time / s

B= 0 mT B = 740 mT, perpendicular

itotal

= -25 mA cm-2

13

Morphology aspects

i= -25mA cm-2; B=0mT; pH=3 i= -25mA cm-2; B=740mT, ; pH=3

14

i= -50mA cm-2; B=0 mT; pH=2 i= -50mA cm-2; B=445mT, ||; pH=2

i= -50mA cm-2; B=740mT, ; pH=2

15

B = 0 mT

B = 445 mT, B||E B = 530 mT, BE

Itotal= -35 mA cm-2

0 100 200 300 400 500 600

1,00

1,25

1,50

1,75

itotal

= -35 mA cm-2

Rq(

B)/

Rq(

B=

0mT

)

B / mT

B perpendicular E B parallel E

N

ZZR

2avei

q

• Rq is the standard deviation of the Z values within the given area,

calculated from the topography image (the height),

• Zi is the current Z value,

• Zave- the average of Z values within the given area

• N- number of points from the given area.

16

Iron content in Weight percent2-nd Electrolyte

-120 -100 -80 -60 -40 -20 0

14

21

28

35

42

49F

e co

nten

t /

Wt %

i / mA cm-2

B=0 mT

Fe in bath- 0.4 Wt %

Composition of the bath:0.5 M NiSO4*6H2O; 0.07 M FeSO4*7H20; 0.4 M H3BO3; pH=2

17

Influence of the B field on iron content

0 150 300 450 600 7500

6

12

18

24

30

36

Fe

co

nte

nt

/ W

t%

B / mT

(B, E) perpendicular (B,E) paralleli

total= -50 mA cm-2

0 150 300 450 600 7500

6

12

18

24

Fe

co

nte

nt

/ W

t%

B / mT

(B,E) perpendicular (B,E) paralleli

total= -70 mA cm-2

18

Partial current of Hydrogen evolution

0 150 300 450 600 750

14

16

18

20

22itotal

= -70 mA cm-2

i H2

/ m

A c

m-2

B / mT

B E B E

0 150 300 450 600 7506

8

10

12

14

16

18

i H2 /

mA

cm

-2

B / mT

B E B E

itotal

= -50 mA cm-2

19

Roughness of the deposit

0 150 300 450 600 750

0,70

0,75

0,80

0,85

0,90

0,95

1,00

Rq(

B)/

Rq(

B=

0mT

)

B / mT

B E B E

i= -70 mA cm-2

0 150 300 450 600 7500,8

0,9

1,0

1,1

1,2

1,3

1,4

1,5

1,6

i= -50 mA cm-2

Rq

(B

)/R

q(B

=0

)B / mT

B E B E

20

Morphology aspects

1.3µm 1.3µm 1.3µm

Itotal= -50 mA cm-2

B=0 mT B=406 mT, B||EB=528 mT, BE

21

Conclusions

Fe content is changing with the B field in an opposite way for the two electrolytes investigated

Fe content of the permalloy increases for (B E) and is almost constant for (B || E)

Roughness and hydrogen evolution are not influenced in the case that B is parallel to E

Specific morphology is generated in the presence of a B field

Thank you!