| 摘要 |
PROBLEM TO BE SOLVED: To efficiently select a powder material having high reactivity by selecting a powder material having specified or larger ignition loss in a specified temp. range. SOLUTION: A powder having the following properties is selected. This powder shows >=0.3 wt.% ignition loss at a temp. of 400 to 1000 deg.C, preferably >=0.5 wt.%, and more preferably it has >=90 wt.% SiO2 content, especially >=95 wt.%, and further <=40μm average particle size, especially <=20μm. The ignition loss of quartz stone at a temp. of 400 to 1000 deg.C is measured and its reactivity is predicted by the measured value to evaluate the quartz stone source. Namely, quartz stone has a cluster structure of condensed silicate ion [(SiO2 )n ] and the end of the cluster forms SiOH with bonded H ion, so that a quartz stone having large clusters has less SiOH present, while a chert having small clusters has more SiOH present. Since Si-OH is dehydrated by heating, a chert with a small dehydration rate (ignition loss) is evaluated as poor in the reactivity, while a quartz stone with a large dehydration rate is evaluated as rich in the reactivity.
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