Fabrication of Chemically Doped, High Upper Critical Field Magnesium Diboride Superconducting Wires
Controlled chemical doping of magnesium diboride (MgB2) has been shown to substantially improve its superconducting properties to the levels required for high field magnets, but the doping is difficult to accomplish through the usual route of solid state reaction and diffusion. Further, superconducting cables of MgB2 are difficult to fabricate because of the friable nature of the material. In this Phase I STTR project, doped and undoped boron fibers were made by chemical vapor deposition (CVD). Several >100m long batches of doped and undoped fiber were made by CVD codeposition of boron plus dopants. Bundles of these fibers infiltrated with liquid magnesium and subsequently converted to MgB2 to form Mg-MgB2 metal matrix composites. In a parallel path, doped boron nano-sized powder was produced by a plasma synthesis technique, reacted with magnesium to produce doped MgB2 superconducting ceramic bodies. The doped powder was also fabricated into superconducting wires several meters long. The doped boron fibers and powders made in this program were fabricated into fiber-metal composites and powder-metal composites by a liquid metal infiltration technique. The kinetics of the reaction between boron fiber and magnesium metal was investigated in fiber-metal composites. It was found that the presence of dopants had significantly slowed the reaction between magnesium and boron. The superconducting properties were measured for MgB2 fibers and MgB2 powders made by liquid metal infiltration. Properties of MgB2 products (Jc, Hc2) from Phase I are among the highest reported to date for MgB2 bulk superconductors. Chemically doped MgB2 superconducting magnets can perform at least as well as NbTi and NbSn3 in high magnetic fields and still offer an improvement over the latter two in terms of operating temperature. These characteristics make doped MgB2 an effective material for high magnetic field applications, such as magnetic confined fusion, and medical MRI devices. Developing fusion as an energy source will dramatically reduce energy costs, global warming, and radioactive waste. Cheaper and more efficient medical MRI devices could lower examination costs, find potential health problems earlier, and thus also benefit society as a whole. Other potential commercial applications for this material are devices for the generation and storage of electrical power, thus lowering the cost of delivered electricity.
- Research Organization:
- Specialty Materials, Inc., Lowell, MA
- Sponsoring Organization:
- USDOE - Office of Energy Research (ER); USDOE - Office of Solar Thermal, Biomass Power, and Hydrogen Technologies (EE-13); US - Atomic Energy Commission
- DOE Contract Number:
- FG02-04ER86228
- OSTI ID:
- 850578
- Report Number(s):
- DOE/ER/86228; TRN: US0701892
- Country of Publication:
- United States
- Language:
- English
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12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
36 MATERIALS SCIENCE
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CHEMICAL VAPOR DEPOSITION
CRITICAL FIELD
ENERGY ACCOUNTING
ENERGY SOURCES
FABRICATION
GREENHOUSE EFFECT
LIQUID METALS
MAGNESIUM
MAGNETIC FIELDS
RADIOACTIVE WASTES
SUPERCONDUCTING CABLES
SUPERCONDUCTING MAGNETS
SUPERCONDUCTING WIRES
magnesium diboride
high temperature superconductor
plasma synthesis
nano-sized particle
flux pinning
upper critical magnetic field
liquid metal infiltration
powder-in-tube