Ceramic–glass composite high temperature seals for dense ionic-conducting ceramic membranes

A basic principle for selecting inorganic sealing materials for dense ionic-conducting ceramic membranes is described for high temperature permeation/reaction experiments. Based on this principle ceramic–glass composite seals consisting of the Pyrex glass and the ceramic powder of the membrane were developed and successfully used to seal a number of different dense ceramic membranes at high temperatures. The ceramic–glass composite seal is typically composed of 40–50 wt.% membrane material powder, 20–50 wt.% Pyrex glass and 5–20 wt.% additive such as sodium aluminate and boron oxide. The properties of ceramic–glass composite seal can be tailored to obtain suitable wettability, viscosity, chemical inertness, thermal expansibility, and bonding strength for good sealing results. A success rate for sealing these ceramic membranes of nearly 100% is possible using the ceramic–glass composite recipe if the correct sealing procedure, including seal paste preparation, is carefully followed.