SOFC Sealing with Thermiculite 866 and Thermiculite 866 LS

Abstract

This paper outlines the structure and properties of a unique compression sealing material that is entirely free of any organic component which has been giving excellent sealing in SOFC service for a number of years. The paper also discusses a new material that combines the advantages of a compression seal with that of a glass seal to provide a compression sealing material needing as little as 0.1 MPa surface stress in order to achieve excellent levels of tightness.

Room temperature and high temperature sealing properties and compression properties of compressive gaskets made of micrometric vermiculite particles

“…This leak rate value at 800°C which might be considered as a permeability leak because of the absence of surface leakage is ten times the one found (1.5 · 10 −4 atm·cm 3 ·s −1 ) at room temperature for our vermiculite seal pressed at 200°C but the disagreement might be attributed to the different working temperatures. The leakage rate values and the dimensions for the circular gaskets mentioned by Hoyes and Rautanen (2013) and Rautanen et al (2014) indicate that the radial permeability of a vermiculite (i.e., "Thermiculite® 866") based gasket should be lower than 10 − 16 m 2 under 10 MPa at 1 bar pressure of He, in agreement with our lower radial permeability values (2 · 10 −19 m 2 ). Moreover, this radial permeability value agrees with the values reported for natural clays at nitrogen or air pressure of about 5 bar (Yang, 2008) or intrinsic permeability values of CallovoOxfordian clay (Enssle et al, 2011;Shao et al, 2011).…”

“…As an example, the infiltration of phlogopite mica by Bi(NO 3 ) 3 or H 3 BO 3 glass has successfully decreased the leak rate to almost 5 · 10 − 4 sccm·cm − 1 (i.e., 8.3 · 10 −6 atm·cm 3 ·s − 1 ·cm − 1 ) after 15 cycles in the range of 100-800°C (Chou and Stevenson, 2004). The last generation of vermiculite based gaskets developed by Flexitallic Company ("Thermiculite® 866") was pretended to be prepared without any organic binder (Hoyes, 2007;Hoyes and Rautanen, 2013). They contain few talc particles and can resist up to 800°C (Hoyes, 2007).…”

Performance of Non‐Destructive Compressive Seals for Reversible Solid Oxide Cells

“…Though seemingly non‐catastrophic, this difference seems to indicate a slightly different chemical interaction between H 2 and Thermiculite compared to the interaction with air and steam, likely due to the reduction of Fe 2 O 3 . However, it should be noted that Thermiculite‐866 was developed to seal SOFCs and that its performance as a sealing material in H 2 has been demonstrated , .…”

Effects of the first heat up procedure on mechanical properties of solid oxide fuel cell sealing materials

“…A C C E P T E D ACCEPTED MANUSCRIPT 9 These results indicate that with Thermiculite CL87 the preferred method of stack assembly should be to apply a major part of the compression already at room temperature as compression at operating temperature requires roughly ten times more stress to induce similar deformation in the sealing material. Applying compression at room temperature gives the sealing material the best chance to compensate for manufacturing and assembly tolerances leading to a gas tight stack with low electrical contact resistance.…”

“…In the case of compressible sealing materials, literature data on the mechanical properties is rather focused on the mineralogical properties of mica-materials [6,8] and data related to designing SOFC stacks is scarce [9,10].…”