T °C - JuSER - Forschungszentrum Jülich

110 Summary
The previous constitutional phases of the glass ceramic composite from the glass
compositions by means of knowledge-based tools have been identified by the XRD
analysis.
In order to achieve a homogeneous distribution of multi-component phases according
to the application conditions, a new approach to tailor the flow properties of the
sealant material was proposed.
First, multi-component oxide systems were used of low possessing liquidus
temperature. This strategy is, however, limited to very narrow compositional ranges.
In the second approach, a significant improvement of the flow ability of the developed
sealant material was achieved. Hereby, phases with low liquidus temperature were
added into the previously developed glass ceramic composite. This above described
low melting oxide phase reacted as a "lubricant". Thus, a massive decrease of the
joining temperature for the previously developed GCC was achieved. Here, the
reduction of the joining temperatures of up to 300 K has been obtained by using a
low-melting phase based on the oxide system Bi2O3-B2O3.
In addition, experimental measurements which were closely associated to the
concept of dynamic viscosity such as rotation and beambendingviscosimetry were
achieved.
In the long-term tests at operating temperature, the crystallization behavior of the
developed sealant materials becomes importance. To estimate the relative
crystallization behavior of glass, two approaches (by Weinberg and by Hrubÿ), which
describing the glass stability against crystallization and the glass formationability,
respectively were used.
The developed glass ceramic composites (GCC) used as sealant material in the
SOFC 800 as well as SOFC 600 reached a good tightness values
(10 -4 - 10 -9 mbar·l·s -1 ).