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Rollers with jackets of quartz ceramic are used for movement of steel sheet in dynamo steel-annealing furnaces. The furnace consists of positions in which i00 rollers are installed. The metal sheet is annealed in a medium of hydrogen at 850-I050~ and the maximum temperature is created in three positions; 73, 74, and 75.According to the data of Creusot-Laire Enterprises, Paris, jackets of Masrock quartz material with 99.8 wt. % of Si02, an open porosity of 12-15%, an apparent density of 1.8-2.0 g/cm 3, a compressive strength of 50-80 MPa, and a coefficient of linear thermal expansion in the 0-i000 ~ range of 0.54"I0-6~ -i has found wide use in world practice for such furnaces.The quartz jackets are made with a weight of about 70 kg (Fig. i). The Jackets must have a smooth outer surface and only small deviations of the dimensions of the fastening holes in the ends. The guaranteed life of imported jackets is not less than 6 months. The actual life of jackets installed for the first time is close to this figure.For the purpose of testing domestic refractories produced according to the method for quartz nozzles [i] in a dynamo steel-annealing furnace, a lot of jackets was prepared.* A portion of the jackets was cast in a gypsum mold placed vertically. In this case, long assembly of the pieces (18-20 h) was necessary and there was a significant (up to 10%) difference in density of the jackets over the height after firing.To eliminate these disadvantages, a method of casting the jackets in a horizontal mold was tested, and the best results were obtained in oscillation of the mold during pouring from 0 to 90 ~ in an axial plane. In pouring in a horizontal mold the time of assembly of the pieces was reduced to 5-6 h and the difference in density of the parts after firing was reduced to 1-2%. The fired pieces were machined by trimming the ends on a cut-off machine, grinding the outer surface on cylindrical grinder, and drilling the end holes on a radial drilling machine.The characteristics of the jackets were 98.3-98.5 wt. % SiO 2, apparent density 1.78-1.80 g/cm 3, open porosity 20-22%, and compressive strength 20-30 MPa.In parallel with the production of this lot, the State Institute for Quartz Glass produced cast jackets of quartz glass. A blank of tubular form was melted from quartz sand concentrate in a rotary furnace. Melting of the sand occurred with simultaneous rotation of the molten glass mass around a graphite electrode, which made it possible to obtain a tubular blank. The ends were cut on the cooled blank and the surface was ground to the necessary dimensions. The SiO 2 content in the jackets depended upon the purity of the original quartz material, the open porosity did not exceed 1%, and the apparent density was 2.0-2.1 g/cm 3. Jackets produced by slip casting in a gypsum mold and produced from molten material were tested in a dynamo steel-annealing furnace in different positions. After 3 months, the jackets were removed from the furnace as the result of build-up on their surface.In the foreign literature th...

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Heat-insulating refractory tiles are widely used for lining the intermediate ladles of continuous-casting plants [1]. Using tiles, together with fillings on the metal surface, not only increases the lining resistance but also reduces the heat losses in the casting process. Figure 1 shows the method of lining the donkey ladles and the use of the heat-insulating tiles.The tiles should satisfy the following demands: ensure the prescribed casting time; reduce to a minimum the heat loss by the metal during casting; protect the reinforcement layer of the lining against destruction during the removal of metal residues from the ladle.DurIng the development of the technology for heat-insulating tiles, we used Soviet experience with the preparation of insulating inserts for ingot molds, and also experience with the production of siliceous concretes [2, 3]. The main component in the batch for making inserts is quartz sand. It possesses the necessary combination of properties, ensuring not only a high resistance to molten metal and slag, but also a low thermal conductivity in the products. Experience with the use of monolithic linings in steel-casting and donkey ladles [4] indicates the high resistance of siliceous materials to metals and slags.A reduction in the thermal conductivity of the inserts is also attained by incorporating in the batch cellulose, asbestos, and other fibers.