| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem in the conventional case that amorphous silica gel is converted to cristofalite by heat-treatment and is not crystallized to quarts. SOLUTION: A Zn compound is added to silica gel of 0.1-20 μm average particle diameter by 0.5-20 wt.% (expressed in terms of ZnO) and this mixture is heat-treated at 900-1,100 deg.C to obtain the objective porous powder of <=20 μm average particle diameter based on SiO2, containing >=0.5 wt.% (expressed in terms of oxide) Zn and having a principal crystal phase comprising quartz as well as internal pores of <=15 μm average pore size. |
