| Description |
v, 62 leaves : illustrations ; 28 cm |
| Summary |
"The magnitude of the thermal expansion of silica brick and its inability to withstand rapid temperature changes gives rise to problems of considerable importance in the manufacture of silica brick. In firing the silica brick, mineralogical changes occur in the quartzite from which the brick is made, in which minerals of lower specific gravity are formed. This results in a permanent expansion of the brick. These mineralogical changes have been thoroughly studied and considerable information is known on the different forms of silica produced at the higher temperatures. If the conditions of firing are such that these changes have progressed but little during the initial firing of the brick it is quite certain that if the brick are used in services where they are subjected to a high temperature, further permanent expansion will occur. This expansion results, generally, in buckling and racking of the silica brick walls. The changes causing this expansion are due to the quartz changing over into tridymite and cristobalite and due to the unconverted quartz changing from alpha to beta quartz. From the thermal expansion data for the different forms of silica, it is seen that tridymite has the most desirable thermal expansions characteristics for silica refractories, and for this reason it is desired to convert as much of the silica possible to the tridymite form in the initial firing of the silica brick"--Introduction, leaves 1-3. |
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