Alternative energy comes closer with advances in hydrogen fuel cell sealing technology

Solid Oxide Fuel Cells (SOFC) have attracted major interest from research and development communities as an alternative source of power, with commercial trials already under way. In these fuel cells electricity is generated via electro-chemical reactions using hydrogen based gas and oxygen as a fuel and oxidant, respectively.

Sealing these units is a critical technical issue that needs further work before they can be put into widespread commercial use. In particular the system chosen must exhibit good gas tightness, adhesion with adjoining components (electrolyte and connector), chemical compatibility, matching coefficient of thermal expansion and electrical insulation.

Recent work from researchers, Apichart Jinnapat, Sirithan Jiamsirilert and Sumittra Charojrochkul from Chulalongkorn University and Thailand's National Metals and Materials Technology Center, and published under AZojomo* (OARS)**, looked at ceramic adhesives and ceramic-glass composites. These materials were examined in terms of their chemical and thermal compatibilities with respect to potential use in SOFCs.

The researchers found that all materials tested displayed good compatibility with the yttria-stabilised zirconia (YSZ) electrolyte and 430 stainless steel interconnector system. In general glass-ceramic composite materials sealed better than ceramic adhesives. Their sealing properties were also found to be superior after being subjected to thermal cycling. The most promising sealing material was a 80/20 Pyrex glass/YSZ composite material which recorded a leakage rate as low as 2.41 x 10 -4 cm 3/min cm.