IDEA #5V1UYX Superconducting Nanostructural Magnesium-Diborade Based Material For Cryogenic Electrical Machines

SUPERCONDUCTING NANOSTRUCTURAL MAGNESIUM-DIBORADE-BASED MATERIAL FOR CRYOGENIC NANOMATERIALS ELECTRICAL MACHINES Description At the Institute for Superhard Materials (ISM) of the Na- tional Academy of Sciences of Ukraine (Kiev, Ukraine) in cooperation with the Institut für Physikalische Hochtech- nologie e.V. (IPHT, Jena, Germany), the superconducting MgB2-based nanostructural (15-37 nm average grain size) materials with highest for nowadays superconductive (Fig.1) and mechanical characteristics have been developed by high pressure (2 GPa)-high temperature (HP-HT) synthe- sis. The materials have the following characteristics: at 20 K critical current jc≥1000-100 кА/сm2 up to 3 Т field and the field of the irreversibility Hirr=8 Т, trapped magnetic field В=2 Т, hardness НV=12.1 ± 0.08 GPa at P=4.9 N, fracture toughness k1C=7.6± 2.0 МPа×m1/2, Young modulus Е=220 GPа and near-theoretical density. The MgB2 produced without additions has a critical current density in zero mag- netic field of 918 kA/cm2 at 20 K and of 149 kA/cm2 at 35 K; MgB2 with Zr added at 20 K in zero field has jc=1800 kA/cm2. Fig.1 Generalized de- pendences of jc on mag- netic field, μ0H, for HP- HT-synthe-sized MgB2 without and with addi- tions of Ta, Ti, Zr (2 and 10 wt %) The MgB2 ingots can be HP-HT synthesized in the shape of cylinders up to 63 mm in diameter and 20 mm in height, square plates of sizes up to 25×25×10 mm3 and rectangular plates of sizes up to 25×21×10 mm3 (Fig.2a). HP-HT syn- thesized MgB2-based materials are about tree times cheaper than MT-YBCO ceramics. Rather big rings or tubes can be produced using precom- paction by broaching with a subsequent sintering (Fig. 2b), jc = 8 kA/cm2 at 20 K. The world-first MgB2-based electromotor has been con- structed from high pressure-high temperature synthesized MgB2 in cooperation with MAI and IPHT (Figs. 3, 4). Innovative Aspect and Main Advantages Interest for the electric machines that are working at the liquid hydrogen temperature is caused by the modern tech- nological progress aimed at the substitution of fuel for air- crafts, combustion engines of autotransport and watertrans- port (submarines) for hydrogen as well as due to the devel- opment of the electrical power networks by which the elec- trical power should be transmitted at a great distances through the superconductive cables at the liquid hydrogen temperature and using liquid hydrogen as cooling agent. Because of this the superconductive electromotors and pumps for liquid hydrogen, which are more efficient than the traditional ones due to the essentially lower weight, much higher speed of operation in the reversion regime and higher specific output power on the rotor surface, will be of a high demand when changing to technologies utilizing liq- uid hydrogen. MgB2-based materials are rather cheap and easily produced. With increased dimensions of the high- pressure chamber, it would be possible to produce blocks of higher dimentions. Areas of Application Nanostructural MgB2 - based materials nowadays are most promising for cryogenic machines and devices (magnetic bearings, MAGLEV transport, electromotors, pumps for liquid gases, fly-wheels energy storage systems, fault cur- rent limiters, etc.) working at hydrogen temperatures (20 K). Stage of Development The developed nanostructural MgB2 –based material (UA patent 68888 А) has at present the highest level of super- conductive characteristics known for MgB2-based materials from literature. The comparative tests of MgB2-based and MT-YBCO- based motors at the same temperature condi- tions have shown that MgB2-based motor competitive in such applications. Contact Details Contact person: Prikhna Tatiana Institute for Superhard Materials of the NAS of Ukraine Address: 2, Avtozavodskaya Str. , 04074 Kiev, Ukraine Tel/Fax: (380-44) 430-11-26 Mob.: 8(097) 467-18-27 E-mail: prikhna@mail.ru prikhna@iptelecom.net.ua (a) (b) Fig.2 View of MgB2 –based blocks HP-HT synthesized measuring 17×17×5 mm3, 25.5×17×5 mm3 (a) and of a ring of size D58×d53×h 22 mm synthesized at 1 Ar atm (b). 1 cosϕ η 1600 N, W MgB2 0.75 1200 0.5 800 0.25 400 0 0 I, A 5 5.5 6 6.5 7 7.5 Fig.3 MgB2-based rotor (40 mm in diameter and 75 mm long) of SC motor manufactured in cooperation with the Moscow State Aviation Institute, Russia (MAI) and IPHT (Jena, Germany) and its characteristics at 20 K. (a) (b) Fig. 4 General view (a) and principal scheme (b) of the world-first MgB2-based motor developed and constructed in the MAI, from high pressure-high temperature synthesized MgB2 at the ISM.