Electrodeposition of biaxially textured nickel substrates for coated conductor by magnetic texturing

Article abstract of DOI:10.1016/j.physc.2004.02.231

An innovative method to fabricate biaxially textured nickel substrates applicable to coated conductor is developed. This method used the industrially scalable electrodeposition method combined with external magnetic field. The biaxially textured Ni layer was formed by electrodeposition process under external magnetic field. The electrodeposited Ni substrate has been characterized by means of X-ray diffraction and shows well-developed biaxial texture (Δθ～7.29°, Δφ～8.14°). A CeO ₂ buffer layer was epitaxially grown on the electrodeposited Ni substrates subsequently by thermal evaporation. In addition, a continuous processing of long tape was tried to test the compatibility of electrodeposition with further scale-up. The grown 20 cm-long Ni tape shows good crystallinity but non-uniform texture. Pinhole-free and smooth surface was obtained by additives and electropolishing. The magnetic texturing in the electrodeposition process offers a simple and economical way to quasi-single-crystalline metal substrates suitable for coated conductor.

Full text of DOI:10.1016/j.physc.2004.02.231

Physica C 412–414 (2004) 848–852
www.elsevier.com/locate/physc
Electrodeposition of biaxially textured nickel substrates
for coated conductor by magnetic texturing
a,
a
Jaimoo Yoo , Young-Kuk Kim , Jaewoong Ko , Kyu-Hwan Lee ,
a
a
*
b
Hee-Gyoun Lee , Dojun Youm , Hyung-Sik Chung
c
d
a
Korea Institute of Machinery and Materials (KIMM), 66 Sangnam-dong, Changwon, Kyungnam 641-010, South Korea
b
Korea Polytechnic University, Kyungki 429-450, South Korea
c
Department of Physics, Korea Advanced Institute of Science and Technology, 305-701 Taejon, South Korea
d
Ajou University, Suwon, Kyungki 442-749, South Korea
Received 29 October 2003; accepted 24 February 2004
Available online 25 June 2004
Abstract
An innovative method to fabricate biaxially textured nickel substrates applicable to coated conductor is developed.
This method used the industrially scalable electrodeposition method combined with external magnetic field. The
biaxially textured Ni layer was formed by electrodeposition process under external magnetic field. The electrodeposited
Ni substrate has been characterized by means of X-ray diffraction and shows well-developed biaxial texture
(
Dh ꢀ 7:29ꢀ, D/ ꢀ 8:14ꢀ). A CeO
2
buffer layer was epitaxially grown on the electrodeposited Ni substrates subsequently
by thermal evaporation. In addition, a continuous processing of long tape was tried to test the compatibility of elec-
trodeposition with further scale-up. The grown 20 cm-long Ni tape shows good crystallinity but non-uniform texture.
Pinhole-free and smooth surface was obtained by additives and electropolishing. The magnetic texturing in the elec-
trodeposition process offers a simple and economical way to quasi-single-crystalline metal substrates suitable for coated
conductor.
ꢁ
2004 Elsevier B.V. All rights reserved.
PACS: 74.72.Bk; 74.78.Bz
Keywords: Biaxial texture; Magnetic texturing; Electrodeposition; Ni substrates
1
. Introduction
The YBa Cu O
ductor is one of the most promising high temper-
ature superconducting tapes for electrical devices
1]. Superconducting grains in the coated conduc-
[
(YBCO)-based coated con-
tor with high J are required to be aligned to
2
3
7ꢁx
c
within a few degrees [2]. The strong biaxial texture
of superconductor can be achieved by transfer of
biaxial texture from biaxially textured metallic
substrates. One of promising approach to produce
biaxially textured substrates is rolling-assisted
biaxially textured substrates (RaBiTSe) method
*
Corresponding author. Tel.: +82-55-280-3542; fax: +82-55-
280-3399.
E-mail address: yjm1682@kmail.kimm.re.kr (J. Yoo).
0
921-4534/$ - see front matter ꢁ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.physc.2004.02.231

J. Yoo et al. / Physica C 412–414 (2004) 848–852
849
[
3]. The RaBiTSe process uses industrially scal-
2. Experimental
able rolling and annealing technology. However,
one of the important shortcomings of YBCO
Electrodeposition has been performed in the
aqueous electrolyte solution at 70 ꢀC under
external magnetic field. The electrolyte solution
was a Watts-type bath containing nickel sulfate
hexahydrate, boric acid, and nickel chloride
hexahydrate. The magnetic field (B) was generated
by electromagnet and the angle between current
and magnetic field was 45ꢀ (Fig. 1). Nickel was
electrodeposited on a electropolished surface of
copper plate (1 cm · 1 cm) for 50 min at about 5 A/
coated conductor on RaBiTSe is lower J
e
value
compared with high J value. That is, since
c
metallic substrate is 50 times as much thick as
YBCO layer, J value is 1/50 of J . Moreover, Ni
e
c
tape thinner than 50 lm by conventional thermo-
mechanical process is difficult to handle and roll
uniformly.
Thin films obtained by electrodeposition can be
easy to control the thickness like a copper foil less
than 10 lm for PCB (printed circuit board) and
apply the continuous process to succeeding coat-
2
dm . The thickness of grown Ni foil is ꢀ30 lm and
2
measured tensile strength is 80 kgf/mm . After
ing steps. Therefore, J of the conductor could be
electrodeposition, copper substrate has been re-
moved by etching with acidic solution to fabricate
a freestanding nickel layer suitable for further
buffer layer growth.
e
improved by electrodeposition. Compared with
thermomechanical process, the manufacturing cost
of electrodeposition process is very small, espe-
cially in the production of thin metallic foils. In
addition, metallic foil fabricated by electrodepos-
ition process shows high tensile strength which
may be oriented from the small grain size of
metallic foil (a few micrometers). Thus electrode-
position process has advantages such as easy
thickness-control, cost-effectiveness, and high
strength of metallic layers. Generally, metallic
layers obtained by conventional electrodeposition
process have a tendency to have certain fiber tex-
ture even in the optimized process. If a certain
external force were applied during electrodeposit-
ion process, the texture of metallic layer would be
changed to be non-fiber texture. We paid attention
to the magnetic force as the external force.
Magnetic fields applied during electrolysis pro-
duce very significant effect on various aqueous
electrolytic processes. For example, Virlan et al.
reported that iron electrodeposited under magnetic
field has significantly increased hardness and re-
duced property [4]. Dash et al. reported that
magnetic fields increase the current efficiency of
chromium deposition [5]. In particular, it was re-
ported that applying external magnetic field in
electrodeposition process change the texture coef-
ficient of metal deposit and induce non-fiber tex-
ture [6,7]. In this letter, we report an innovative
electrodeposition processing of Ni layer with
excellent biaxial texture comparable to RaBiTSe
tape.
2
A CeO buffer layer was grown on the electro-
deposited nickel to test the compatibility of sub-
strate with further buffer layer growth. The buffer
layer has been deposited with thermal evaporation
technique at the substrate temperature of 700 ꢀC.
The detailed conditions for oxide film growth can
be found elsewhere [8].
3. Results and discussion
The crystallographic texture of the electrode-
posited nickel foil has been characterized with
X-ray diffraction method (XRD). Fig. 2(a) shows a
h-rocking curve for the electrodeposited nickel
layer. The FWHM (full width at half maximum)
Fig. 1. A schematic of electrodeposition facility set-up. ‘‘C’’
and ‘‘A’’ indicates cathode and anode, respectively. The angle
between current and magnetic field was set to be 45ꢀ.

850
J. Yoo et al. / Physica C 412–414 (2004) 848–852
of h-rocking curve ðDhÞ evaluated to be about
.29ꢀ implying a good out-of-plane texture of
7
electrodeposit. As shown in Fig. 2(b), the (1 1 1)
pole figure constitutes well-established fourfold
symmetric discrete peak contours, which also tes-
tifies excellent in-plane alignment of the Ni foil
deposited under magnetic field. The /-scan profile
presented in Fig. 2(c) was fitted with Gaussian
function and the D/ of plated nickel was estimated
to be about 8.14ꢀ. Hence it is shown that the
microstructure of Ni layer electrodeposited under
magnetic field is characterized to be biaxial tex-
ture. Development of biaxial texture in electrode-
position under magnetic field can be attributed to
preferential growth of grains in easily magnetized
direction of FCC metals [6].
26 28 30 32 34
25 30 35 40 45 50 55
(
a)
2θ
5
10
15
20
25
30
0
(c)
90
180
270
360
(b)
θ
φ
Fig. 3(a) presents an XRD2 h–h scan profile for
Fig. 3. X-ray diffraction profiles for the CeO
2h–h scan, (b) h-rocking curve at the Bragg condition of (2 0 0)
reflection of CeO
, (c) a /-scan profile at the tilt angle of 54.7ꢀ.
2
buffer layer; (a)
a CeO
peaks for both nickel and CeO
2
buffer layered nickel foil. Although XRD
layer shows small
2
2
amount of (1 1 1) reflections, their intensities are
not significant. The integrated intensity ratios,
½
I
ð2 0 0Þ=Ið2 0 0Þ þ Ið1 1 1Þꢂ were estimated to be 0.99 and
CeO buffer layer indicates highly c-axis oriented
2
0
.95 for nickel layer and CeO layer, respectively.
2
microstructures for both nickel and CeO buffer.
The Dh of CeO which quantifies the degree of
2
The dominance of (h 0 0) reflections in the XRD
profile for both electrodeposited nickel layer and
2
out-of-plane orientation was evaluated to be about
7.50ꢀ as shown in Fig. 3(b). The /-scan profile
presented in Fig. 3(c) contains well-established
four main peaks spaced by 90ꢀ of / angle, al-
though /-scan profile also contains a few peaks
indicating partial misalignment of grains. The de-
gree of in-plane texture of CeO
be about D/ ꢀ 8:27ꢀ. Therefore it is concluded
that the CeO layer has been epitaxially grown on
2
was estimated to
2
5
10 15 20 25 30 35 40 45
biaxially textured Ni surface obtained by electro-
deposition under magnetic field and the electro-
deposited Ni layer is highly compatible with
further buffer layer growing process.
(
a)
θ
9
0
1
00
1
20
60
8
0
6
0
1
80
2
50
30
4
0
As a trial to improve surface quality, very small
quantity of organic additives (sodium lauryl sul-
fate) was employed in the electrolyte solution or
the surface of Ni layer was electropolished in the
acidic solution. As shown in Fig. 4(a) and (b),
surface of Ni layer electropolished in the acidic
solution appeared to be glossy compared with that
of as-deposited Ni layer. Moreover, the addition
of organic chemical into the electrolyte solution
removed the pinhole and improved the surface
quality (Fig. 4(c) and (d)).
2
0
1
0
10
330
0
90
180
270
360
2
40
300
φ
(b)
270
(c)
Fig. 2. X-ray diffraction profiles for Ni layer fabricated by
electrodeposition under magnetic field; (a) h-rocking curve at
the Bragg condition of (2 0 0) reflection of nickel, (b) an X-ray
pole figure at the Bragg condition of nickel (1 1 1) reflection,
and (c) a /-scan profile at the tilt angle of 54.7ꢀ.

J. Yoo et al. / Physica C 412–414 (2004) 848–852
851
of nickel tape is not uniform through the length
Fig. 5(b)). This can be attributed to non-uniform
(
distribution of magnetic field by small bore-size of
electromagnet (10 cm in diameter). Further
experimental study with uniform magnetic field is
in progress.
4. Summary
In summary, a nickel foil with excellent biaxial
texture has been successfully fabricated with elec-
trodeposition process under magnetic field. It was
shown that the external magnetic field induced in-
plane texture of nickel layer due to magnetocrys-
talline anisotropy. The electrodeposited nickel foil
shows well-developed biaxial texture (Dh ꢀ 7:29ꢀ,
Fig. 4. Surfaces of electrodeposited layer prepared with various
conditions: (a) as-deposited Ni layer, (b) after electropolishing
of surface, (c) no additives in the electrolyte solution, and (d)
with additives in the electrolyte solution.
D/ ꢀ 8:14ꢀ). A CeO
2
buffer layer was epitaxially
grown on the electrodeposited nickel substrates by
thermal evaporation, which endorses the compat-
ibility of substrate with further buffer layer pro-
cessing.
The surface of electrodeposited Ni layer was
shown to be improved by electropolishing and
employing an organic additives in the electrolyte
solution. In addition, a continuous processing of
long tape was tried to test the compatibility of
electrodeposition with further scale-up. The grown
In addition, a 20 cm-long Ni tape was electro-
deposited on metallic drum and separated to pro-
duce long Ni foils. Fig. 5(a) shows an
electrodeposited 20 cm-long Ni tape to test the
compatibility of electrodeposition with scale-up
process. The grown tape shows glossy surface and
uniform appearance. However, the biaxial texture
20 cm-long Ni tape shows good crystallinity but
non-uniform texture.
Cube-textured Ni substrates made using this
technique offer a potential route for fabricating
e
substrates suitable for high-J wire capable of
carrying high currents in high magnetic fields and
at elevated temperatures.
Acknowledgements
This work was financially supported by the
Ministry of Science and Technology of Korea
through the NRL program.
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