Materials Science Forum
Vols. 556-557
Vols. 556-557
Materials Science Forum
Vol. 555
Vol. 555
Materials Science Forum
Vol. 554
Vol. 554
Materials Science Forum
Vol. 553
Vol. 553
Materials Science Forum
Vols. 551-552
Vols. 551-552
Materials Science Forum
Vol. 550
Vol. 550
Materials Science Forum
Vols. 546-549
Vols. 546-549
Materials Science Forum
Vols. 544-545
Vols. 544-545
Materials Science Forum
Vols. 539-543
Vols. 539-543
Materials Science Forum
Vols. 537-538
Vols. 537-538
Materials Science Forum
Vols. 534-536
Vols. 534-536
Materials Science Forum
Vols. 532-533
Vols. 532-533
Materials Science Forum
Vols. 530-531
Vols. 530-531
Materials Science Forum Vols. 546-549
Paper Title Page
Abstract: Galvanic properties were evaluated on bare and anodized Ti-1023 titanium alloy which
coupled to Ni-electroplated, Zn-electroplated, Cd-electroplated 30CrMnSiA and anodized LY12,
respectively. Corrosion properties including open circuit potential (Eoc) of each material, galvanic
corrosion potential (Eg), and corrosion current (Ig) of the couples were monitored in conjunction
with a Model 263A potentiostat system. Corrosion current density (Īg) and average value of
corrosion potential (Ēg) were calculated from Ig-time and Eg-time curves, respectively. Corrosion
morphology was observed on a optical microscope (OM) and corrosion mechanisms were analyzed
and discussed. The corrosion resistance of Ti-1023/LY12 couple was significantly improved by
Ti-1023 anodized coating. However, the coating accelerated the dissolve of the three electroplated
coatings in the other galvanic couples, resulting in a heavy corrosion attack on 30CrMnSiA steel.
1821
Abstract: Magnetic field texturing of superconducting oxides has shown the possible existence of
intrinsic solid nuclei surviving above the melting temperature Tm and governing the solidification.
Tiny crystals could survive above Tm and act as growth nuclei with undercooling ratios θ= (T-Tm)/Tm
larger than the theoretical value −2/3 if a negative supplementary volume energy −ε v is added in the
Gibbs free energy change associated to the formation of a critical cluster. A double layer of opposite
charges could create the solid-liquid interface electrostatic -εv. The observed maximum values θ1 and
the dimensionless surface energies α1ls calculated for 38 elements assuming that their melts
homogeneous, used to determine εv(θ). The εv values at T=Tm were equal to 21.7% of the fusion
heat per volume unit. The quantity α2ls
3× Sm was nearly the same for all elements, α2ls being the
dimensionless surface energy and Sm the fusion entropy. After melting these tiny crystals around
Tm2=1.20Tm, all the undercooling ratios could tend to -2/3. The bidimensional texture of Bi2212,
Bi2223 tapes can be induced by these nuclei during crystal growth when the prereacted compounds in
the sheath are melted and annealed at a weak overheating temperature smaller than a critical value.
1827
Abstract: A superconducting magnet with a magnetic energy of E = B2/2μo [J/m3] has to overcome
a magnetic force of P = B2/2μo [Pa] in the same expression. This means that a high-field 20 T
superconducting magnet produces an electromagnetic force of 160 MPa. In order to stand such a large
force, Nb3Sn superconducting wires are usually reinforced by the hard-copper housing as an external
reinforcement method or the stainless steel winding as a mechanical backup of an outermost Nb3Sn
coil. If we focus on a compact superconducting magnet like a cryocooled superconducting magnet, a
high-strength superconducting wire with a small diameter size of 1- 2 mm is required. The High-Field
Laboratory for Superconducting Materials, IMR, Tohoku University has developed Nb3Sn wires
internally reinforced with CuNb or CuNbTi composite. These high-strength Nb3Sn wires were
successfully employed to construct the unique compact cryocooled 28 T hybrid magnet and the
cryocooled 18 T high-temperature superconducting magnet. In addition, we found that the prebending
effect for high-strength Nb3Sn wires outstandingly improves the Tc, Bc2 and Ic properties. As a next
step, we intend to develop new Nb3Sn strand cables with the strong mechanical property of 500 MPa,
applying the prebending effect for a future 22 T-φ400 mm room temperature bore superconducting
magnet of a 50 T-class hybrid magnet.
1841
Abstract: Ag-sheathed Bi2223 composite tapes with interfilamentary resistive barriers were
successfully fabricated by using a powder-in-tube (PIT) method and their AC loss properties at 77 K
are evaluated. The mixture of Ca2CuO3 and 30 wt% Bi2212 was used as the barrier material for tape
fabrication to make an electromagnetic decoupling between the filaments. The barrier layers formed
on all surfaces of hexagonal monocore wires by a dip-coating method, and several pieces of the coated
wires were stacked and inserted into an Ag tube. Subsequently, the composites deformed into tape
shape and subjected to a standard process consisting of a flat rolling and sintering. Degradations in
the Jc values at 77 K and self-field by introducing the barriers were estimated to be at most 15%. The
transverse resistivity and AC loss properties under AC external magnetic fields for the barrier tapes
were examined and compared with those for the tape without barriers. The results showed that an
introduction of Ca2CuO3 barriers was effective to suppress the electromagnetic coupling among the
filaments and also to reduce the magnetization losses under parallel transverse field. The fabrication
of the barrier tapes on the order of several meters, together with the uniformity of superconducting
properties along a length direction has been also presented.
1849
Abstract: This work reports some new studies related to critical aspects in the development of
coated conductors (CC). New bi-axially textured tapes based on commercial copper alloys were
fabricated and tested as substrates for LZO buffer layer deposited by chemical solution deposition
(CSD). Such a layer form cube texture on NiW5 and Cu55Ni45 with an identical or even better
texture than that of the substrate. It was shown that a S c(2x2) sub-layer formed at the metallic
surface as a positive effect on the nucleation. The crystallisation of LZO on Cu55Ni45 still has to be
improved, being inhibited by trapped C in the film. Recent progresses using our continuous
MOCVD system are shown. A CC fabricated by an all MOCVD process has been obtained on
SS/YSZIBAD substrate with high transport critical current (170 A/cm-width, at 77 K). It is also
shown that LZOMOD can efficiently protect Ni5W RABITS from oxidation during deposition of
CeO2 layer by MOCVD under 30-40% O2 partial pressure. This opens the possibility to fabricate a
CC on RABITS by MOCVD. This shows that a mixed MOD/MOCVD approach could be
efficient. Finally a 2m long CC SS/YSZIBAD has been tested for fault current limiter applications.
Best limitation was observed at 86 K where an equivalent energy of 340 J has been dissipated in
the CC during 12 ms without apparent damage of the CC. In a subsequent operation, the CC was
however destroyed. The causes are discussed in the perspective to design better architectures for
this application.
1855
Abstract: By controlling pulse number of laser ablation, we prepared a series of quasi-multilayers of
YBa2Cu3O7-δ/M (M=incomplete oxide layer) namely 70×(40/n) (n = 2, 5, 10 and 20, pulse number of
M) which were characterised with nano-scale precipitates. While the texture properties of Y123
inside qusi-multilayer hardly change, its Tc appeared much different depending on the doping level of
M. X-ray θ-2θ scanning and pole figures indicated that the different growth-controlled precipitates
occured inside Y123 films. In the case of M=YSZ (Yttria Stabilized Zirconia), nanosized perovskite
precipitates of BaZrO3 formed as a result of solid state reaction of YSZ with Y123, leading to Tc
obviously decreasing with increasing of n. In the case of M=Y2O3, however, Tc did not decrease so
much at the studied range of n due to no solid state reaction mentioned above. Magneto-transport and
field angular dependence showed that the critical current density in films with lower doping content
(such as n = 2) was improved in large ranges of field and temperature, suggesting tailorable
enhancement and anisotropy of flux pinning force.
1865
Continuous Deposition of Buffer Layers for YBCO Coated Conductor Using Reactive Magnetron Sputtering
Abstract: A reel-to-reel deposition system was set up for studying YBCO coated conductor.
Continuous deposition of multi-layer CeO2/YSZ/Y2O3 buffer layers was carried out on 10mm-width
biaxially textured tape of NiW using the reactive dc magnetron sputtering technique. A continuous
and uniform buffer layer with good texture was presented over length. For 10–meter-long tapes, the
φ-scan FWHM values of Y2O3 (222), YSZ (111), and CeO2 (111) were 7.77°, 7.68° and 7.93°,
respectively. The rocking curves showed that the average FWHM values of Y2O3 (004), YSZ (002),
and CeO2 (002) were 5.02°, 4.67° and 4.44°, respectively. The microstructure and interfaces of buffer
layers were observed by scanning electron microscopy (SEM) and Auger electron spectrum (AES).
YBCO layer was prepared by magnetron sputtering technique as well on the short samples.
1871
Abstract: A new approach of Cu-Ni substrate is reported, where the cubic textured Cu tape was
fabricated by thermal-mechanical process, then a Ni layer was electro-deposited on the cubic textured
Cu substrate. This approach is also suitable for fabricating long cubic textured metallic substrate for
coated conductors. The formation of substrate texture and its thermal stability were investigated by
XRD. After electro-depositing Ni layer, the sample has sharper cubic texture with ω = 5.2o and φ =
7.1o, and samples’ texture becames even better (ω = 5 o and φ = 5.2o) after annealing at 950°C for
30min.
1877
Abstract: A new series of ReBiO3 (RBO, Re=Y, Sm or other lanthanide) layers have been prepared
on single crystal LaAlO3 or SrTiO3 respectively by a low-cost chemical solution deposition (CSD)
method, and their structures have been investigated. With deferent Re element, the ReBiO3 phase has
a similar cubic lattice with the pseudo-cubic lattice parameter a’ of about 3.81~3.94Å, which is
closely matched to that of the ReBa2Cu3Ox (RBCO). In addition, these ReBiO3 phase are stable when
they are sintered on 750~1050°C. After annealed below 850°C in air, highly c-axis oriented
ReBiO3 layers can be formed on the (100) plane of single crystal LaAlO3 or SrTiO3. Observed under
SEM, these layers appear very dense, smooth, pinhole-free and crack-free morphology. With the
matched lattice parameter, lower annealing temperature, good grain-orientation and smooth surface,
ReBiO3 layers should be candidates for the buffer layers of RBCO coated conductor. As a proof, a
superconducting layer of YBCO has been deposited also by a CSD approach on one of these layers
and show good texture and expected superconductivity.
1881
Abstract: YBCO bulks with submicron Y2BaCuO5 particles have been prepared under oxygen partial
pressures of 0.21atm and 1atm, respectively, by the powder melting process (PMP). The
microstructures, oxygen contents and critical current densities of the samples have been investigated.
The results showed that the sample grown under P(O2) = 1 atm contained Y2BaCuO5 particles with a
little bigger average size and had a slightly higher density of stacking faults than the one prepared
under P(O2) = 0.21 atm. Oxygen content measurements indicated that the as-grown sample under
P(O2) = 1 atm had a higher oxygen content. After post-annealing in flowing oxygen, the oxygen
content of the P(O2) = 1 atm sample was still higher than that of the P(O2) = 0.21 atm sample. They
were examined to be 6.94 and 6.88 with X-ray diffraction for the two oxygenated samples,
respectively. Magnetization measurements have been performed on the two types of oxygenated
samples and critical current densities (Jc) have been calculated based on the extended Bean critical
state model. The P(O2) = 0.21 atm sample exhibits Jc values of 5.47×105 A/cm2 and 2.22×104 A/cm2
in 1 T magnetic field at 20K and 77K, respectively. The P(O2) = 1 atm sample, meanwhile, has Jc
values of 9.46×105 A/cm2 and 1.47×104 A/cm2 in 1 T magnetic field at 20K and 77K, respectively.
Moreover, at 20K, the Jc of the P(O2) = 1 atm sample is higher than that of the P(O2) = 0.21 atm
sample in an applied magnetic field up to 5 T. At 77K, however, the Jc of the P(O2) = 1 atm sample
drops more quickly than that of the P(O2) = 0.21 atm sample. The mechanisms of the different
microstructures, oxygen contents and magnetic field dependence behaviors of Jc for the two kinds of
samples have been discussed.
1887