Thermal conductivity of magnesite refractories in the range 500–1800°C

Conclusions An experimental setup was developed for studying the thermal conductivity of refractories up to 2300°C on the hot face of the specimen.In the average temperature range of 500–1800°C a study was made of the thermal conductivity of magnesite refractories of different porosity. The experimental data obtained satisfactorily agree with well-known literature and calculated values for the thermal conductivity coefficients.Translated from Ogneupory, No. 1, pp. 17–21, January, 1972.     

Effect of capillary condensation on water sorption by composite calcium chloride in a porous matrix sorbents

To develop a model of water sorption from air by composite salt in a porous matrix sorbents, the effect of capillary condensation was studied [1]. It was shown that, at high humidity of incoming air, it is necessary to take into account the capillary condensation of water in small pores of the matrix because the capillary condensation significantly affects the concentration and temperature profiles in the sorbent bed and leads to intense moisture accumulation at the bed inlet. The model was used to study the kinetics of water vapor sorption in a flow adsorber with a fixed bed of calcium chloride in porous aluminum oxide and calcium chloride in a porous carbon-carbon composite Sibunit sorbents.     

Mass spectrometric investigation of the thermodynamic properties of glass melts in the Cs2O-B2O3-SiO2 system at high temperatures

The composition of the vapor and the activities of cesium metaborate CsBO₂ in glass melts of the Cs₂O-B₂O₃-SiO₂ system at a temperature of 1020 K are determined using high-temperature mass spectrometry. The activities of the individual oxides Cs₂O, B₂O₃, and SiO₂ in glass melts of the Cs₂O-B₂O₃-SiO₂ system at a temperature of 1020 K are calculated by the Wagner method from the obtained values of the activities of CsBO₂. The integral and excess Gibbs energies are determined.     

The effect of heat on the molecular weight of poly(ethyl 2-cyanoacrylate) adhesive

Steel–steel ethyl 2-cyanoacrylate adhesive bonds have been thermally aged and the polymeric material isolated from the glue line. Molecular weight measurement by gel permeation chromatography suggest that a significant degree of post-curing occurs followed by a slight decrease in molecular weight. This decrease in molar mass is not considered large enough to explain the observed decrease in bond strength. It is postulated that poly(ethyl 2-cyanoacrylate) undergoes thermal degradation in a manner similar to that reported for poly(methyl methacrylate). The loss in bond strength is thought to be due to the disruption of the polymer–metal interface by monomer molecules produced during the thermal depolymerization.     

Mathematical methods of experiment design for determining the optimum production parameters for magnesite — Spinel roof brick

Conclusions It was shown that it is possible and advantageous to apply mathematical methods of experiment design when developing and analyzing the technological processes in the production of refractories.The interpolation models were constructed with very little effort, are important for practical purposes and cannot be obtained by conventional experimental methods in which the factors are varied one at a time.The calculations showed that for a product having a cold-crushing strength of 685 kg/cm² and an open porosity of 12% the spinel must contain 60% alumina and no chromite, the molding composition must contain 10% of this spinel, and the molded product must be fired at 1700°C.Translated from Ogneupory, No. 2, pp. 19–23, February, 1975.     

Bestimmung von Schwermetallen in Ölen,Fetten und Futtermitteln

Determination of Heavy Metal Traces in Oils, Fats and Feeding-Stuffs Atomic absorption spectroscopy has proved to be the best method for the determination of lead, cadmium and mercury in fats, oils and feeding-stuffs, whereas colorimetry is best for the determination of arsenic. For each substrate the most suitable digestion method is described. Recoveries and detection limits of the determination methods are shown.     

The thermomechanical and deformation properties of fibrous heat-insulation refractories

Conclusions An analysis was carried out of the deformation characteristics in uniaxial compression and of the creep and compression strength at temperatures of 400–1100°C of heat-insulation slabs produced from kaolin wool and an organic adhesive.The impregnation with an organic adhesive reduces the deformation of the slabs at temperatures of 20–600°C to a significant extent.The kaolin wool heat-insulation slabs can be used as compensation and construction material for the regenerations of blast furnaces including large-capacity furnaces because the slabs are capable of supporting long-term loads up to 1 kg/cm² at temperatures of 20–1100°C.Translated from Ogneupory, No. 7, pp. 51–54, July, 1976.     

Periclase —spinel products from magnesite powder with high alumina content

Conclusions Periclase-spinel articles with low contents of chromite made from magnesite powder containing magnesia-alumina spinel have a high range of physicochemical properties (except spalling resistance) and completely satisfy the requirements in service for the roofs of open-hearth and walls of electric steel-melting furnaces.With an increase in the content of magnesite in the fine constituent, it is possible to obtain products of the same quality from magnesite powder with a high porosity (up to 20–23%).The change in ratio of chrome spinel and magnesia-aluminous spinel in the periclase-spinel articles toward a certain increase in the latter is worthy of attention and requires further investigation.Translated from Ogneupory, No. 2, pp. 11–15, February, 1966.     

Study of mass transfer in a sheet glass furnace with boiling in the melting zone

The results of a luminescent indicator study of the conditions of neutralization of a glass melt in sheet glass furnaces equipped with boiling systems are reported. It was shown that the process of dilution of the indicator improved significantly in the furnace with boiling, and this began immediately after the indicator entered the furnace. After the boiling system was mastered, the mass transfer parameters of the furnace in production of sheet glass increased by 15–20%.Translated from Steklo i Keramika, Nos. 5–6, pp. 11–13, May–June, 1994.     

Predicted and observed initial short circuit current for lead-acid batteries

Initial short circuit currents have been observed using our electronic short circuit switch and also predicted from terminal voltage and ohmic resistance according to Ohm's law for several kinds of lead-acid batteries in various states-of-charge. Ohmic resistance was measured by the d.c. step and the a.c. impedance methods. The predicted and the observed values have been compared in order to establish a prediction method for initial short circuit current. A good agreement was obtained, the root mean square percentage deviation of the predicted value from that observed being only 219%, which confirms the validity of the prediction method for the initial short circuit current.