Thermal conductivity of single crystals of M1−x M x ′F2 (M = Ca, Sr; M′ = Mn, Co) isovalent solid solutions

The thermal conductivity of single crystals of the Ca_0.99Co_0.01F₂, Ca_0.97Co_0.03F₂, Sr_0.99Mn_0.01F₂, Sr_0.989Mn_0.01Co_0.001F₂, and Sr_0.995Co_0.005F₂ solid solutions has been measured in the temperature range 50–300 K. The results demonstrate that doping of CaF₂ and SrF₂ crystals with small amounts of isovalent transition metal impurities is accompanied by a significant reduction in thermal conductivity.     

Industrial experience with petroleum coke in ferrosilicon production

The industrial use of low-ash petroleum coke instead of coke nuts in ferrosilicon production is considered. The quality and behavior of the petroleum coke in high-temperature smelting are studied. The use of petroleum coke in smelting ferrosilicon proves efficient.     

Electrical properties and mechanism of electrical conductivity of ruthenium dioxide-base thick films

Translated from Poroshkovaya Metallurgiya, No. 5(329), pp. 68–71, May, 1990.     

DIRECT CONTACT DRYING OF A MOVING POROUS STRIP

Combined heat transfer and evaporation dynamics are analyzed during drying of a continuously moving, porous strip which is in direct contact with a heated plate. A transient, quasi-two-dimensional model of conjugate heat transfer between a hot massive externally /internally heated plate and wet porous strip moving along the plate is developed by accounting for evaporation dynamics. The model consists of four conjugate energy conservation equations with proper boundary/interface conditions which describe the heat transfer in four distinct zones (1-electrically or indirectly heated massive metal plate, 2-thin superheated vapor film resulting from vaporization of water in the porous strip that separates hot plate and porous strip, 3-dry region of the porous strip, and 4-wet region of the porous strip). The relevant dimensiouless parameters governing the problem are identified, and results of parametric calculations are reported to gain fundamental understanding of the process.     

Pyrochemical method of salvaging weapons plutonium in oxide for fabricating mixed fuel for fast reactors

Experimental results of investigations of pyrochemical conversion of weapons plutonium into plutonium oxide for fabricating fast-reactor fuel are presented. Weapons plutonium was hydrogenized by hydrogen at 220°C, after which the plutonium hydride obtained was acidified at 550–560°C with the formation of PuO₂. To increase fire and explosion safety of the process, a mixture of oxygen with nitrogen, helium, or argon was used or nitriding with nitrogen and oxidation of plutonium mononitride were introduced. The particle size of the plutonium oxide powders obtained was less than 15 μm. The powders showed poor flowability, but after granulation they were suitable for fabricating kernels with mixed fuel. The gallium was removed by reduction of Ga₂O₃ by hydrogen to Ga₂O, which was sublimated. The mixed-fuel kernels sintered at 1600–1700°C in a hydrogen atmosphere contained <0.001 wt.% gallium, and their density was 94–97% of the theoretical value.     

Paired tooth cutting of cylindrical gears

Russian Engineering Research -