IDEA #2CB1XK Superconducting Nanostructural Magnesium-Diborade-Based Material For Cryogenic Electrical Machines

THE SCIENCE AND TECHNOLOGY CENTER IN UKRAINE SUPERCONDUCTING NANOSTRUCTURAL MAGNESIUM%DIBORADE%BASED MATERIAL FOR CRYOGENIC ELECTRICAL MACHINES Description At the Institute for Superhard Materials (ISM) of the National Academy of Sciences of Ukraine (Kiev, Ukraine) in cooperation with the Institut fur Physikalische Hochtechnologie e.V. (IPHT, Jena, Germany), the super(cid:28) conducting MgB2(cid:28)based nanostructural (15–37 nm aver(cid:28) age grain size) materials with highest for nowadays super(cid:28) conductive (Fig. 1) and mechanical characteristics have been developed by high pressure (2 GPa)(cid:28)high tempera(cid:28) ture (HP(cid:28)HT) synthesis. 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(cid:28)theoretical density. The MgB2 produced without additions has a critical current density in zero magnetic field of 780 kA/cm2 at 20 K and of 62 kA/cm2 at 35 K; MgB2 with Zr added at 20 K in zero field has jc=1800 kA/cm2. The MgB2 ingots can be HP(cid:28)HT synthesized in the shape of cylinders up to 30 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(cid:28)HT syn(cid:28) thesized MgB2(cid:28)based materials are about tree times cheap(cid:28) er than MT(cid:28)YBCO ceramics. Rather big rings or tubes can be produced using precompaction by broaching with a sub(cid:28) sequent sintering (Fig. 2b), jc = 8 kA/cm2 at 20 K. The world(cid:28)first MgB2(cid:28)based electromotor has been construct(cid:28) ed from high pressure(cid:28)high temperature synthesized MgB2 in cooperation with MAI and IPHT (Figs. 3, 4). Fig. 1. Generalized de% pendences of jc on magnet% ic field, μμ0H, for HP%HT% synthe%sized MgB2 without and with additions of Ta, Ti, Zr (2 and 10 wt %) Fig. 2. View of MgB2 %based blocks HP%HT synthesized meas% uring 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) 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 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 40 Innovative Aspect and Main Advantages Interest for the electric machines that are working at the liquid hydrogen temperature is caused by the modern technological progress aimed at the substitution of fuel for aircrafts, combustion engines of autotransport and water(cid:28) transport (submarines) for hydrogen as well as due to the development of the electrical power networks by which the electrical power should be transmitted at a great dis(cid:28) tances through the superconductive cables at the liquid hydrogen temperature and using liquid hydrogen as cool(cid:28) ing agent. Because of this the superconductive electromo(cid:28) tors and pumps for liquid hydrogen, which are more effi(cid:28) cient 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 sur(cid:28) face, will be of a high demand when changing to technolo(cid:28) gies utilizing liquid hydrogen. MgB2(cid:28)based materials are rather cheap and easily produced. With increased dimen(cid:28) sions of the high(cid:28)pressure chamber, it would be possible to produce blocks of higher dimentions. Areas of Application Nanostructural MgB2(cid:28)based materials nowadays are most promising for cryogenic machines and devices (magnetic bearings, MAGLEV transport, electromotors, pumps for liq(cid:28) uid gases, fly(cid:28)wheels energy storage systems, fault current limiters, etc.) working at hydrogen temperatures (20 K). Stage of Development The developed nanostructural MgB2(cid:28)based material (UA patent 68888 А) has at present the highest level of super(cid:28) conductive characteristics known for MgB2(cid:28)based materi(cid:28) als from literature. The comparative tests of MgB2(cid:28)based and MT(cid:28)YBCO(cid:28)based motors at the same temperature conditions have shown that MgB2(cid:28)based motor competi(cid:28) tive 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(cid:28)44) 430(cid:28)11(cid:28)26 Mob.: 8(097) 467(cid:28)18(cid:28)27 E(cid:28)mail: prikhna@mail.ru, prikhna@iptelecom.net.ua SCIENCE AND INNOVATION. Special Issue, 2007