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...