| 摘要 |
<p>Pure ZrO2 is produced from Zr silicate, e.g. zircon sand, by thermal cleavage without additive, then lixiviation of finely granular material by stirring 2-10, pref. 6-8 hr. with aqs. soln. containing 10-50 wt.% NaOH or 14-70% KOH or corresponding hydroxide mixture at 60-110 degrees C, alkali hydroxide: SiO2 molar ratio being 0.5-4:1, pref. 1-2:1. Crystal size of ZrO2 solidifying from melt may be regulated by cooling melt slowly, pouring into flat moulds or quenching. Process avoids contamination of ZrO2 with decomposing agent. Product has low enough SiO2 and alkali oxide content for use in ceramics.</p> |
