Manufacture, properties and application of open-pore sintered glasses and open-pore sintered glass-ceramics

Abstract

A new process was developed for the manufacture of open-pore sintered glass and glass-ceramics with defined porosity according to the filler principle. Fine-grained glass powder is homogeneously mixed with an inorganic salt of specified grain size and sintered. The salt is washed out, its grain size allowing the adjustment of the mean pore diameter between 5 and 350 μm accompanied by a sharp pore size distribution. The quantity of inorganic salt determines the open pore volume between 20 and 80 vol%. The manufacture of an open-pore sintered glass-ceramic requires a crystallizable glass powder. Depending on the choice of glass powder and inorganic salt compositions inert behavior can be maintained, or ion exchange takes place leading to new compositions and properties. Properties are a consequence of defined porosity and the microstructure of the skeleton material. Maximum working temperatures may reach about 750 °C in the case of sintered glasses and up to 1400 °C in the case of sintered glass-ceramics. The application of the open-pore materials results from their selectively adjustable porosity: filtration of gases and liquids; separating processes; storage, conduction and distribution of liquids; electric and thermal insulation; catalyst carriers; biotechnology.