Porous silica, silica-cobalt, silica-zirconia and zirconia membranes were synthesized by the sol-gel method. Multi-step coating (two, six, and ten steps) was used to reduce the defectiveness of the mesoporous layer. Scanning electron microscopy (SEM) images indicated that an increase in the number of coating steps improved the mesoporous layer quality. The results obtained from gas permeability tests with nitrogen and argon, however, indicated a reduction in the gas permeability with increasing coating steps. The reduction in gas permeability from two to six coating steps was more pronounced than from sixto ten- coating steps. It was found that six-step coating was economically justified in obtaining a uniform mesoporous layer. The results of pore radius calculations by Knudsen flow mechanism revealed that the pores in the silica, silica-cobalt, and zirconia membranes were in the mesoporous range. The sols with a mean particle size more than 100 nm are not recommended for synthesis of mesoporous layer free of defects. Furthermore, the type of acid used as a catalyst is also important in obtaining a layer without defectiveness.

中文翻译：

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涂布步骤对陶瓷膜中孔层均匀性和透气性的影响

通过溶胶-凝胶法合成了多孔二氧化硅，二氧化硅-钴，二氧化硅-氧化锆和氧化锆膜。使用多步涂覆（两步，六步和十步）来减少中孔层的缺陷。扫描电子显微镜（SEM）图像表明，涂覆步骤数目的增加改善了中孔层的质量。然而，从用氮气和氩气进行的透气性测试获得的结果表明，随着涂覆步骤的增加，透气性降低。气体渗透率从两个涂覆步骤减少到六个涂覆步骤比从六个涂覆步骤减少到十个涂覆步骤更为明显。发现六步涂覆在经济上是合理的，以获得均匀的中孔层。根据克努森流动机理计算的孔半径，结果表明，二氧化硅，二氧化硅-钴，和氧化锆膜在中孔范围内。不建议将平均粒径大于100 nm的溶胶用于合成无缺陷的中孔层。此外，用作催化剂的酸的类型对于获得没有缺陷的层也很重要。