Effect of fabrication route on density and connectivity of MgB<sub>2</sub>filaments

Viljamaa, J.; Kòváč, Pavol; Hušek, I; Melíšek, T; Štrbı́k, V.; Dobročka, Edmund

doi:10.1088/1742-6596/234/2/022041

Cited by 6 publications

(7 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The is the change in the values at room temperature and just above the , i.e., at 40 K in the case of . The controversy of the ideal value has been discussed in [40] and the value of 7.3 [41] is used here. The measured resistivity at 40 K and calculated values of and are displayed in Table I.…”

Section: Experimental the Monofilamentarymentioning

confidence: 99%

Comparison on Effects of ${\rm B}_{4}{\rm C}$, ${\rm Al}_{2}{\rm O}_{3}$, and SiC Doping on Performance of ${\rm MgB}_{2}$ Conductors

Viljamaa

Kulich

Kòváč

et al. 2011

IEEE Trans. Appl. Supercond.

View full text Add to dashboard Cite

Several MgB 2 monofilamentary samples are prepared to evaluate the effects that the doping compounds B 4 C, Al 2 O 3 , and SiC have on critical current density ( c ) and the c dependency of magnetic flux density ( ) of the sample. All of the samples in this study have Nb sheaths and are manufactured using in situ precursor powders and the Powder-in-Tube fabrication method. The amounts of added impurities are 10 wt.% for B 4 C and Al 2 O 3 , and 3, 10, and 20 wt.% for SiC. A reference sample without any doping is also prepared. All of the samples are heat treated between 650 and 800 C for 30 minutes. The transport c ( ) characteristics are measured at 4.2 K and the magnetic c ( ) behavior is obtained in varied temperatures up to 30 K.The changes in connectivity, or effective cross-section, are also evaluated by performing resistivity measurements on the samples after removal of the sheath. Furthermore, the pinning forces of the samples are evaluated from the magnetic measurements.Index Terms-Connectivity, current density, heat treatment, impurity addition, magnetic field effects, MgB 2 .

show abstract

Section: Experimental the Monofilamentarymentioning

confidence: 99%

Comparison on Effects of ${\rm B}_{4}{\rm C}$, ${\rm Al}_{2}{\rm O}_{3}$, and SiC Doping on Performance of ${\rm MgB}_{2}$ Conductors

Viljamaa

Kulich

Kòváč

et al. 2011

IEEE Trans. Appl. Supercond.

View full text Add to dashboard Cite

show abstract

“…These hydrostatically extruded wires with Fe and Nb/Cu sheaths had not yet sufficient filament uniformity after drawing and/or rolling [11]. It was shown that filament density prior to the final heat treatment can increase the final current densities in MgB 2 [12,13]. While the cold high pressure densification (CHPD) by 1.85 GPa was able to increase the critical current density, J c , of MgB 2 /Fe wire by more than factor of 2 at 4.2 K [12], only around 10% J c improvement has been obtained for MgB 2 /Ti tape subjected to cold isostatic pressing (CIP) by 1.5 GPa [13].…”

Section: Introductionmentioning

confidence: 99%

“…It was shown that filament density prior to the final heat treatment can increase the final current densities in MgB 2 [12,13]. While the cold high pressure densification (CHPD) by 1.85 GPa was able to increase the critical current density, J c , of MgB 2 /Fe wire by more than factor of 2 at 4.2 K [12], only around 10% J c improvement has been obtained for MgB 2 /Ti tape subjected to cold isostatic pressing (CIP) by 1.5 GPa [13]. Improved transport properties have been shown also for high filament density stainless steel (SS) sheathed and cold drawn MgB 2 wires subjected to several deformations without tension stress [14].…”

Section: Introductionmentioning

confidence: 99%

As-deformed filament's density and transport currents of MgB2/Ti/Glidcop wire

Kòváč

Hušek

Pachla

et al. 2011

Journal of Alloys and Compounds

View full text Add to dashboard Cite

“…Grain connectivity can be roughly estimated by the resistivity change between room temperature and 40 K (Δρ (ρ 300 K -ρ much larger than the ideal Δρ value. to Viljamaa et al [33], the Δρ values may be attributed to the existence of non-superconductive areas. The presence of macropores and MgO in these samples can create the nonsuperconductive areas, which affects the connectivity between grains.…”

Section: Resistance-temperature (R-t) Measurementmentioning

confidence: 67%

Microstructure and superconducting properties of MgB₂ bulks prepared from Mg + B + Mg(BH₄)₂ composites

Luo

Zi-Geng

Cai

et al. 2019

Supercond. Sci. Technol.

View full text Add to dashboard Cite

Practical applications of the MgB 2 prepared by the in situ method are usually limited because of the pores formed by the volatility of Mg. In order to improve the performance of MgB 2 bulks, MgB 2 bulks were fabricated through an in situ synthesis method with composites of B powder, Mg powder, and 10-100 wt% Mg(BH 4 ) 2 powder. The superconducting properties and grains structure of these MgB 2 bulks were investigated, such as onset superconducting transition temperature (T c ), critical current density (J c ), porosity, resistivity (ρ), and grain connectivity. For the MgB 2 bulk prepared from 80 wt% Mg(BH 4 ) 2 powder added composites, the J c (1 T) value at 5 K was 4.1×10 5 A cm −2 and the onset T c value was 37.5 K. Moreover, the microstructure of these MgB 2 bulks was also analyzed using scanning electron microscope (SEM). The MgB 2 bulk with less pores can be prepared with moderate Mg(BH 4 ) 2 powder added composite as precursor. The composites also provide raw materials for preparing high-quality in situ MgB 2 superconducting wires. Keywords: Mg(BH 4 ) 2 , MgB 2 , composite precursor, porosity, high J c

show abstract

Effect of fabrication route on density and connectivity of MgB₂filaments

Cited by 6 publications

References 31 publications

Comparison on Effects of ${\rm B}_{4}{\rm C}$, ${\rm Al}_{2}{\rm O}_{3}$, and SiC Doping on Performance of ${\rm MgB}_{2}$ Conductors

Comparison on Effects of ${\rm B}_{4}{\rm C}$, ${\rm Al}_{2}{\rm O}_{3}$, and SiC Doping on Performance of ${\rm MgB}_{2}$ Conductors

As-deformed filament's density and transport currents of MgB2/Ti/Glidcop wire

Microstructure and superconducting properties of MgB₂ bulks prepared from Mg + B + Mg(BH₄)₂ composites

Contact Info

Product

Resources

About

Effect of fabrication route on density and connectivity of MgB2filaments

Cited by 6 publications

References 31 publications

Comparison on Effects of ${\rm B}_{4}{\rm C}$, ${\rm Al}_{2}{\rm O}_{3}$, and SiC Doping on Performance of ${\rm MgB}_{2}$ Conductors

Comparison on Effects of ${\rm B}_{4}{\rm C}$, ${\rm Al}_{2}{\rm O}_{3}$, and SiC Doping on Performance of ${\rm MgB}_{2}$ Conductors

As-deformed filament's density and transport currents of MgB2/Ti/Glidcop wire

Microstructure and superconducting properties of MgB2 bulks prepared from Mg + B + Mg(BH4)2 composites

Contact Info

Product

Resources

About

Effect of fabrication route on density and connectivity of MgB₂filaments

Microstructure and superconducting properties of MgB₂ bulks prepared from Mg + B + Mg(BH₄)₂ composites