Selection of oxide crucibles for vaporization of metals

Conclusions Thermodynamic computations were performed on the interaction of oxide crucibles with metal vaporized from them. The results obtained enable a sound, prior selection of oxide crucibles for vaporization of a specific metal.Translated from Ogneupory, No. 8, pp. 54–56, August, 1968.     

Interaction of oxide phases of graphite-containing crucibles with secondary silumins

A thermodynamic investigation of the interaction between the oxide phases Al₂Si₂O₇ and SiO₂ of graphite-containing crucibles and metallic melts of the Al — Si system is presented. Al₂O₃ and metallic silicon are shown to be the equilibrium products of the reactions.Translated from Ogneupory i Tekhnicheskaya Keramika, No. 8, pp. 15 – 16, August, 1996.     

Graphite-containing crucibles

Conclusions Conclusions made by semidry pressing have excellent properties and a longer life than plastic-formed crucibles.During service in high-frequency furnaces the life of crucibles is somewhat longer than in ovens.During service the crucibles do not undergo substantial changes in phase composition and properties.     

Properties of graphite-containing crucibles

Conclusions A study of the thermal conductivity and the electrical resistivity of the specimens of the graphite-containing TGN, TGG, and TKG type crucibles shows that the characteristics of these properties significantly differ depending on the type of the crucibles and the zones in different parts of a given crucible.It is expected that the properties of a given type of crucibles can vary from product to product because of the differences in the compositions and the size fractions of the original raw materials, the postfiring differences in the material, and the structural nonuniformities resulting from compaction.We established the differences in the properties of the graphite-containing crucibles (that depend on the nature of the atmosphere) as a function of temperature.Heating the crucibles in an oxidizing atmosphere leads to partial burning-off (depletion) of their main component (graphite) and to a reduction of the thermal and electrical conductivity of the material of the crucibles.It must be considered that the thermal conductivity of the crucibles working in carbon dioxide atmosphte is 5–10% less than that of the crucibles working in argon atmosphere.Translated from Ogneupory, No. 5, pp. 10–14, May, 1987.     

Inorganic binders for graphite-containing crucibles

Some technological features of obtaining acid silica sol from slags of ferroalloy production are considered. A new binder (Vanal analog) was synthesized on the basis of the V₂O₃−Al₂O₃−TiO₂−SiO₂−Na₂O system. Advantages of using slag binders in the fabrication of graphite-containing crucibles are demonstrated. Articles using these binders exhibit lower open porosity, gas permeability, specific volume, and permeable-pore size. The thermal stability of crucibles for casting black silumin, fabricated using the silica sol binder, was 3.8 times that of crucibles with the usual binder. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 3, pp. 27–30, March, 1997.     

Carborundum-graphite crucibles for melting copper-base alloys

Conclusions Carborundum-graphite crucibles holding 500 kg of liquid metal worked reliably in a high-frequency furnace for 35 – 40 melts in the case of the copper-chromium hardener, and up to 75 melts in the case of the BKh-08 alloy.On account of the low specific resist nce of the carborundum-graphite crucibles, the furnace can be easily adjusted, and the melting of the metal speeded up; there is good sintering of the electro-corundum rammed mixture, which can act as the melting receptable if the crucible is damaged.Carborundum-graphite crucibles are quite suitable for melting copper-base alloys with a silicon content up to 0.2 – 0.3%.     

Corundum crucibles for vaporizing aluminum in vacuo

Conclusions Corundum-based materials are suitable for the large crucibles used in industrial equipment for aluminum-plating rolled strips in vacuo. The durability in the plating process of crucibles fabricated from corundum with high-alumina cement as binder is good (several hours) and they can be recommended for industrialscale testing.Translated from Metallurgical Machinery. Translated from Ogneupory, No. 7, pp. 46–50, July, 1976.     

Production of high-quality graphite crucibles for metallurgy

Processes for the manufacture of crucible graphite with high performance characteristics are considered. Among these processes are the use of highly graphitized needle coke as a filling agent, the vibromolding of a starting coke-pitch mixture, the use of medium-temperature coal-tar pitch impregnation-burning cycles, the burning of molding compounds in metal containers, and the graphitization of burnt materials in graphite cylinders. The latter two techniques decrease a temperature drop across the bulk raw material in the course of thermal treatments and, consequently, minimize the appearance of cracks due to a decrease in thermal stresses. All of the recommended techniques can be implemented at current electrode plants, and they can considerably improve the quality of the manufactured crucible graphite. In this case, the quality of the resulting materials can correspond to world standards.