Fibrous heat-insulating materials

Influence of magnesium silicate and mullite-siliceous fibers on the efficiency of heat-insulation inserts

“…The values of Ico n influence IDo r when the pore size is more than i0 mm and the temperature drop of the pore walls is 3~3~K [4]. Since such conditions are seldom attained, ~por Ico n can be disregarded [2][3][4] and then Ipor~rad.…”

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For a long time to come, casting of killed steel into ingots will continue to be the principal stage in the processing of liquid steel into rolled products.It has been established [i] that about 60% of all the heat of the upper part of the ingots is lost via the top of the metal, and 40% via the side walls.This determines the compositions of the materials and the manner of their use for eliminating heat losses by the head of the ingot, the reduction of the head edge, and the increase in the yield of suitable metal from liquid steel.The materials established in the lateral part of the top of the ingot must have minimal thermal conductivity.It is known [2] that among the available industrial media, minimal thermal conductivity is exhibited by air.For lateral heating of the head part of ingots it is most expedient to use heat insulators --disperse systems --with a highly porous structure, formed by fibrous refractory materials.The thermal conductivity of the gas phase (air) of the heat insulator under comparable temperature conditions is 30-100 times less than that of its solid phase [3]. The overall effective thermal conductivity in such insulators is made up of the thermal conductivity of the solid body, Iso , and the thermal conductivity of the pores, I

, filled with = + I s~ por air [4].

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