Among the physical constants concerning with refractories and refractory raw materials, the specific gravity is one of the most important physical constants. Especially in the case of manufacturing silica brick, specific gravity of silica product has important meaning on judgement of its quality, because during the burning of silica brick, raw quartz undergoes several steps of inversions and changes its specific gravity in accordance with each phase.
Therefore, the rapid measuring method of specific gravity of silica substances is useful not only for the judgement of their quality, but also on the technical management of silica brick burning.
From the above mentioned reasons, we have made a study on the rapid and correct measuring method of specific gravity.
The methods we adopted are those of replacement of powder sample by water as follows:
1) Method by JIS 2205 (de-airing by boiling-out)
2) Method by adding NaCl in water bath for the sake of higher temperature and faster boiling out.
3) Method by shaking-out at room temperature.
4) Method by adding surface active agent to the replacing water.
As the results of comparison among 4 methods as above, we conffirmed that the 4th method is most rapid and correct.
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