Magnetic and structural properties of rapidly quenched Nd-Fe-Co-Ge-B alloys

We have studied the magneto-resistive effect in bulk Y_3/4Lu_1/4Ba₂Cu₃O₇ + CuO composites prepared by the fast-sintering technique. It has been found that the composites exhibit large magnetoresistance in low magnetic fields (<100 Oe) in a broad temperature range (tens of kelvins below the critical temperature T _c). The HTSC-based composites exhibit a much higher sensitivity to weak magnetic fields at liquid-nitrogen temperature as compared to pure HTSC ceramics. By choosing a proper bias current j, it is possible to control the shape of the resistivity-magnetic field ρ(H) characteristic of the composites and to vary the parameter R ₀ = {R(H = 0) ? R(H)}/R(H = 0). Under the condition j > j _c (where j _c is the critical-current density), large values of the magnetoresistance R ₀, up to thousands percent, are obtained in the range of weak magnetic fields (tens of oersteds) at 77 K. This effect is attractive for practical applications of these composite materials as active elements of magnetic-field sensors. The sign of the magneto-resistive effect is positive in contrast to that of manganese oxides. This may be important for some devices.     

Improving thermal insulation for graphitization furnaces

Alternative materials are proposed for the lateral thermal insulation in graphitization furnaces. It is possible to reduce the loss of heat and the consumption of electricity by using carbon dust for insulation, and it is also possible to use plates of thermally and electrically insulating carbon material to hold it in the furnace. Translated from Novye Ogneupory, No. 12, pp. 3–5, December, 2008.     

Evaluation of plastically unstable flow in steel

Institute of Ferrous Metallurgy, Ministry of Ferrous Metallurgy of the USSR. Translated from Problemy Prochnosti, No. 7, pp. 24–26, July, 1989.     

Unfired brick from magnesite-chromite concrete for open-hearth furnace building

Conclusions Unfired brick made of magnesite-chromite concrete with periclase cement, tested in several parts of open-hearth furnaces, showed the same resistance as fired magnesite or chrome-magnesite refractories.Unfired magnesite-chromite brick made of concrete can be used for building structures with air-setting, water-containing cement instead of iron plates.It is necessary to organize the industrial production of unfired goods made of magnesite-chromite concrete using the method developed by UNIIO for extensive testing and subsequent use in open-hearth furnaces.     

Porous alumina aggregates and heat-insulating refractory concretes for use in reducing atmospheres

Conclusions Investigations were carried out on the use of commercial alumina for producing porous alumina aggregates for making heat-insulating high-alumina refractory concretes. It was found that to obtain these concretes with high heat-insulating properties it was necessary to use alumina porous aggregate with a finely porous structure.The introduction into the briquetted plastic bodies, in preparing lightweight aggretate, of unground commercial alumina mixed with finely milled material, and an addition of aluminum fluoride, yields alumina aggregate of a finely porous structure.On the basis of porous alumina aggregates and high-alumina cement we obtained heat-insulating refractory concretes containing 86–89% A1₂O₃ and low concentrations of impurities, which allows us to recommend them for service in reducing atmospheres approximately at temperatures of up to 1300–1400°C.Translated from Ogneupory, No. 1, pp. 42–47, January, 1971.     

Magnesite bodies with a carbon — Phosphate bond

Conclusions We developed magnesite bodies with a combined carbon — phosphate bond in which the coarse grained constituent was impregnated with fused carbon bond, and to the finely milled part we added an alkali metal phosphate. The bodies were characterized by great strength not only in a reducing atmosphere but also in oxidizing atmospheres after the combustion of the carbon bond. It is desirable to use sodium metapolyphosphate (NaPO₃)_n to form the phosphate bond.Translated from Ogneupory, No. 1, pp. 45–51, January, 1971.