Improving the quality of electrical-engineering periclase by antihydration treatment

Conclusions The treatment of powders of electrical engineering periclase in the silicoorganic liquid GKZh-94 makes it possible to eliminate hydration during storage and to increase the electrical resistivity.The solvent for the GKZh-94 has been selected, and the optimal concentration of its solution to ensure the most effective protection of the periclase powders from hydration has been established.Translated from Ogneupory, No. 6, pp. 25–27, June, 1986.     

Effect of calcium oxide on the hydration activity of the powders of electrical-engineering periclase

Conclusions The hydration activity of the periclase powders depends to a significant extent on the hydration of free calcium oxide. The hydration resistance of the powders can be increased by fixing calcium oxide in the hydration-resistant compounds with silicon and magnesium oxides.It is also necessary to decrease the specific surface of the periclase powders for decreasing their ability to absorb moisture.Translated from Ogneupory, No. 8, pp. 9–12, August, 1988.     

The thermal conductivity of periclase and periclase — Spinel refractories

Conclusions It was established that it is possible to vary the thermal conductivity of periclase and periclase- spinel refractories within fairly wide limits by varying their phase composition and structure.Translated from Ogneupory, No. 3, pp. 48–50, March, 1975.     

Two-piece nozzle-batchers for continuous casting of electrical-engineering steel

Conclusions A design and production technology were developed for making fireclay two-piece elongated steelcasting nozzle batchers with an apparent porosity of 14–17%. The resistance of the nozzles is satisfactory and they form a satisfactory jet, despite the retarding action of the stopper plug.The nozzles are being introduced at the Novolipetsk Metallurgical Factory and their production organized at the Semiluki Refractories Factory. The use of elongated nozzles and improved insulation of the working zone in the crystallizer during the continuous casting of electrical-engineering and carbon steel permitted a substantial improvement to be made in the purity of the surface of the cast slabs and the quality of the metal, and also yielded 46,000 rubles annual savings.Translated from Ogneupory, No. 4, pp. 4–6, April, 1967.     

Compactibility of periclase mixtures

Special equipment is used to investigate the pressing regimes of periclase mixtures with different grain compositions. The pressing pressures are presented as a function of the time of action of the load. The dynamics of the variation of the mean density is presented as a function of the pressing time and the pressing pressure. The compactibility of the mixtures is evaluated from the corresponding criterion. Translated from Ogneupory, No. 3, pp. 19 – 21, March, 1996.     

Microhardness of fused periclase

Conclusions The microhardness of fused periclase has been studied. It is shown that the microhardness of periclase is significantly affected by defects in the structure, in particular, by the dislocation density and the presence of impurity oxides.When fused periclase is heat-treated at 1000–1400°C which reduces the dislocation density by approximately two orders of magnitude, the microhardness of periclase is decreased. The reduction in the microhardness helps to increase the electrical resistance of the periclase as a result of both a decrease in the dislocation density and also, obviously, of the change in the packing density of the particles if the electrical resistance is measured in tubular electric heaters.The reduction in the microhardness helps to improve the ease of pressing of the refractory articles manufactured using fused periclase.Translated from Ogneupory, No. 4, pp. 10–13, April, 1984.     

Refractories from fused periclase

Conclusions High-grade refractories can be produced from periclase containing at least 97% MgO by preparing a suitable grain size distribution with a vibro-ground component in the powder, molding in stages at high specific pressures (1500–2000 kg/cm²), and firing for 8 h or more at a high temperature (1750°C or higher).Translated from Ogneupory, No. 6, pp. 5–8, June, 1974.     

Making periclase cement waterproof

Conclusions Waterproofing of pure periclase cement with 1.5% petroleum resin is due to its lower capillary and sorption water absorption; the treatment also prevents caking. The activity of periclase cement that has been waterproofed with petroleum resin remains practically unaltered during storage.Translated from Ogneupory, No. 8, pp.41–44, August, 1967.     

Electroseparation of sintered periclase powders

A laboratory separator and an industrial prototype developed by the Magnezit Integrated Works in cooperation with the Kola Branch of the Mekhanobr Institute for electroseparation of magnesite ores with an elevated content of dolomite and dolomitized magnesite are described.Translated from Ogneupory i Tekhnicheskaya Keramika, No. 12, pp. 27 – 28, December, 1996.     

Mechanical activation of periclase cements

Conclusions Mechanoactivation of periclase cements by using chemically single-type dispersants considerably accelerates the milling of the original powders. This effect is due to solid phase reaction between the cement particles and the amorphized surface of the grains of chemically single-type dispersants.The use of these dispersants increases the strength, density, and especially the thermal-shock resistance of the activated periclase cements.Translated from Ogneupory, No. 4, pp. 11–14, April, 1993.