The sorption of nitrogen in porous compacts of silica and zirconia powders
The sorption of nitrogen in porous compacts of silica and zirconia powders
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DOI：
10.1016/0021-9797(73)90046-5
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发表时间：
1973-03
影响因子：
9.9
通讯作者：
R. Avery;J. Ramsay
中科院分区：
文献类型：
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作者：
R. Avery;J. Ramsay
采用气相冷凝法制备了粒径极小（~ 40 Å）、粒径分布窄的二氧化硅和氧化锆（氧化钇稳定）粉末，该方法没有产生强烈的颗粒团聚。通过测量氮气在- 196°C时的吸附等温线，研究了在- 2中高达100吨压力范围内压实对这些粉末的比表面积和孔结构的影响；表面积、孔径和总孔容均明显减小。结果与压实体的结构模型非常吻合，压实体由规则排列的球形颗粒组成，配位数由压缩程度控制。在最高压紧压力下，获得了I型等温线，这表明当孔隙低于某个临界半径时（由开尔文方程估计为r′- 17 Å），毛细凝聚机制不再起作用。
Silica and zirconia (yttria stabilized) powders with an extremely small particle size (∼40 Å) and a narrow size distribution have been prepared by a vapor-phase condensation process which gave no strong particle agglomeration. The effect of compaction, over a pressure range up to 100 tons in−2, on the specific surface area and pore structure of these powders has been studied by measuring adsorption isotherms of nitrogen at −196°C; marked decreases in surface area, pore size and total pore volume occurred. The results are in close accord with a structural model for the compacts, consisting of regularly packed spherical particles with a coordination number controlled by the extent of compression. At the highest pressures of compaction Type I isotherms were obtained, an indication that with pores below some critical radius-estimated from the Kelvin equation as r̄ - 17 Å, the capillary condensation mechanism is no longer operative.