Peculiarities of high-pressure and hot-pressing manufacture of MgB<sub>2</sub>-based blocks with high critical currents for electrical machines

Prikhna, T. A.; Gawalek, W.; Savchuk, Ya. M.; Sergienko, Nina; Moshchil, Viktor; Wendt, Michael; Habisreuther, T.; Дуб, С. Н.; Melnikov, V. S.; Kozyrev, Artem; Schmidt, Ch.; Dellith, Jan; Litzkendorf, D.; Nagorny, Peter; Dittrich, Ulrich; Sverdun, V. B.; Kovalev, L.K.; Penkin, V.T.; Goldacker, W.; Rozenberg, O. A.; Noudem, Jacques

doi:10.1088/1742-6596/97/1/012022

Cited by 11 publications

(11 citation statements)

References 5 publications

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“…Prikhna et al [17] reported at 10 K a value of B(10 4 ) = 7.8 T for bulk MgB 2 with 10% Ti additive after reaction at 800 • C under a pressure of 2 GPa. Serquis et al [18] reacted in situ wires under HIP conditions (0.2 GPa) and reported at 4.2 K an enhancement of B(10 4 ) up to 1 T. Cold high pressure densification (CHPD) [19] is presented here as an alternative to the just mentioned high temperature treatments.…”

Section: Introductionmentioning

confidence: 99%

Strong enhancement ofJ_candB_irrin binaryin situMgB₂wires after cold high pressure densification

Flükiger

Hossain

Senatore

2009

Supercond. Sci. Technol.

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Cold high pressure densification was found to substantially enhance the critical current density of binary in situ Fe/MgB2 wires. A wire densified at 1.85 GPa exhibited at 20 K and 5 T an increase of Jc by 300% with respect to same wire without the application of pressure. At 4.2 K and 10 T, Jc was found to be increased by 53%. The decrease of the electrical resistance for densified wires reflects an improved connectivity. The values of Birr at 4.2 and 20 K were enhanced up to 0.7 T for densified wires. After applying pressures up to 6.5 GPa at 300 K, the relative mass density dm of the unreacted (B+Mg) mixture inside the filament increased up to 96% of the theoretical density. This corresponds to a relative mass density df in the reacted MgB2 filaments of 73%. A quantitative correlation between filament mass density and critical current density was established.

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Section: Introductionmentioning

confidence: 99%

Strong enhancement ofJ_candB_irrin binaryin situMgB₂wires after cold high pressure densification

Flükiger

Hossain

Senatore

2009

Supercond. Sci. Technol.

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“…There are no precise data about the mass density of the reacted MgB 2 layer in IMD processed wires, but very high Vickers microhardness values were reported, of the order of 1300 kg/mm 2 [19]. For comparison, the Vickers microhardness values for bulk samples obtained by high temperature/high pressure treatments are somewhat higher (up to 1500 kg/mm 2 ) [21], thus suggesting a very high mass density (relative mass density > 90%) in IMD filaments, thus confirming the values of Giunchi et al [22]. The value of J c in the reacted MgB 2 layer of IMD wires is higher than for ex situ and in situ wires: J c (4.2K) at 12 T was reported at 4.5 x 10 4 A/cm 2 [19].…”

Section: Mass Densities Fill Factors and J C In Various Mgb 2 Wire Tmentioning

confidence: 99%

“…In view of the enhancement of the mass density of MgB 2 bulk samples and in situ filamentary tapes, numerous high temperature/high pressure attempts have been undertaken [21,23]. Recently, a new kind of treatment was introduced at GAP in Geneva, the Cold High Pressure Densification or CHPD technique [1].…”

Section: Cold High Pressure Densification (Chpd) Of Short Mgb 2 Wiresmentioning

confidence: 99%

Technical aspects of cold high pressure densification (CHPD) on long lengths of In Situ MgB2 wires with enhanced Jc values

Flükiger

Hossain

Kulich

et al. 2012

AIP Conference Proceedings

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The technical aspects correlated with the observed enhancement of mass density and critical current density in the filaments of in situ MgB 2 wires by means of the recently developed Cold High Pressure Densification (CHPD) are reviewed. The present analysis first summarizes the results obtained by means of a short sample prototype device with anvil lengths of 39 mm. Pressures well above 1 GPa were applied to short wires, causing J c enhancements between a factor 1.5 and 2.3 at 4.2 K and 8 T. At 20 K, the enhancement is much stronger and reaches a factor 3 for binary and 5 for alloyed MgB 2 wires. Based on these results, an automatic machine has been developed allowing a sequential press/release/advance operation. With this machine, which has been very recently installed at GAP in Geneva, in situ MgB 2 wires of lengths up to 10 meters have so far been successfully densified, confirming the J c enhancements obtained with the short sample device. Using an improved anvil geometry, the wall friction was reduced with respect to the short sample prototype device, thus yielding the same J c enhancements, but at considerably lower applied pressures: now, J c max was obtained at 0.85 GPa, in contrast to values between 1.3 and 1.5 GPa for the short sample device. After densifying at this pressure, the value of J c = 1 x 10 4 A/cm 2 at 4.2 K was obtained at 13.2 T over 1 m length, thus corresponding to an enhancement by a factor 2.2 with respect to the non pressed wire. The present results are promising in view of the application of CHPD to industrial wire lengths.

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“…The higher is the amount of these inclusions, the finer they are, and more homogeneously distributed, the higher is the [10]. Up to now our attempts to improve of HP-HT-synthesized by adding SiC with grains of sizes 20-30 and 200-400 nm were unsuccessful: at 10-35 K decreased or remained unchanged [11].…”

Section: Introductionmentioning

confidence: 99%

“…In the experiments on sintering of Type I-H.S. Starck, 0.8% O, 10 and Type II-Alfa Aesar, 98% purity were used. A powder of Ti (30 , purity 95%), Ta (0.…”

Section: Introductionmentioning

confidence: 99%

Formation of Higher Borides During High-Pressure Synthesis and Sintering of Magnesium Diboride and Their Positive Effect on Pinning and Critical Current Density

Prikhna

Gawalek

Savchuk

et al. 2009

IEEE Trans. Appl. Supercond.

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Critical current density ( c ) of high-pressure (2 GPa) manufactured MgB 2 -based superconductors depends on the amount and distribution of higher borides (MgB 12 ) in MgB 2 matrix, which in turn are determined by the nature of the initial components first of all B or MgB 2 and the temperature of sintering or synthesis. Ti and Ta additions can improve c by promoting the higher boride formation via impurity hydrogen absorption, thus preventing MgH 2 detrimental for c being formed, which possibly increases the MgB 12 nucleation barrier. SiC (0.2-0.8 m) addition increases c of MgB 2 , allowing us to get c = 10 6 A cm 2 at 20 K in the 1 T field: pinning is increased by SiC and higher boride grains and there is no notable interaction between SiC and MgB 2 . As the synthesis temperature increases from 800 to 1050 C, Ti and SiC additions may affect the oxygen segregation and formation of Mg-B-O inclusions enriched with oxygen as compared to the amount of oxygen in the MgB 2 matrix, which can also promote an increase in pinning. Materials high-pressure synthesized from Mg and B taken in 1:4, 1:6, 1:7, 1:8, 1:10, 1:12, 1:20 ratios were superconductive with T c of about 37 K. High c (7 10 4 2 10 4 A cm 2 in zero field at 10-30 K, respectively) showed materials with the matrix composition near MgB 12 stoichiometry, they have doubled microhardness of MgB 2 .

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Peculiarities of high-pressure and hot-pressing manufacture of MgB₂-based blocks with high critical currents for electrical machines

Cited by 11 publications

References 5 publications

Strong enhancement ofJ_candB_irrin binaryin situMgB₂wires after cold high pressure densification

Strong enhancement ofJ_candB_irrin binaryin situMgB₂wires after cold high pressure densification

Technical aspects of cold high pressure densification (CHPD) on long lengths of In Situ MgB2 wires with enhanced Jc values

Formation of Higher Borides During High-Pressure Synthesis and Sintering of Magnesium Diboride and Their Positive Effect on Pinning and Critical Current Density

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Peculiarities of high-pressure and hot-pressing manufacture of MgB2-based blocks with high critical currents for electrical machines

Cited by 11 publications

References 5 publications

Strong enhancement ofJcandBirrin binaryin situMgB2wires after cold high pressure densification

Strong enhancement ofJcandBirrin binaryin situMgB2wires after cold high pressure densification

Technical aspects of cold high pressure densification (CHPD) on long lengths of In Situ MgB2 wires with enhanced Jc values

Formation of Higher Borides During High-Pressure Synthesis and Sintering of Magnesium Diboride and Their Positive Effect on Pinning and Critical Current Density

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Product

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Peculiarities of high-pressure and hot-pressing manufacture of MgB₂-based blocks with high critical currents for electrical machines

Strong enhancement ofJ_candB_irrin binaryin situMgB₂wires after cold high pressure densification

Strong enhancement ofJ_candB_irrin binaryin situMgB₂wires after cold high pressure densification