Preparation of Porous Glass Monoliths with an Aligned Pore System via Stretch Forming.

Porous glasses with an aligned pore system were prepared by using a stretch-forming device. For the experiments a sodium borosilicate glass with the composition 62.5 wt% SiO₂, 30.5 wt% B₂O₃ and 7 wt% Na₂O was prepared. The characterization of this glass includes X-ray fluorescence analysis and dilatometry. The applied stretch-forming apparatus allowed the simultaneous phase separation and elongation of the glass samples. The obtained glass templates were chemically treated with hydrochloric acid and sodium hydroxide solution to extract the soluble sodium rich borate phase. The resulting porous glass samples were characterized by environmental scanning electron microscopy and mercury intrusion. Different degrees of pore alignment were realized by varying the parameters of the stretch-forming process. [ABSTRACT FROM AUTHOR]