Mechanical Characterization of Solid Oxide Fuel Cells and Sealants

4
-
4
. The raw materials are SiO
2
(Saint-Gobain), MgO (Panreac), BaCO
3
(Alfa Aesar),
SrCO
3
(Alfa Aesar) and B
2
O
3
(Alfa Aesar), which all have more than 90 % purity. The B
2
O
3 
powders (Alfa Aesar) were melted previously in a gas furnace at 900°C to obtain a glass, thus 
avoiding the hygroscopy of the B
2
O
3 
powder. The raw materials used for preparation of the 
glasses were mixed in a tubular mixer during one hour before calcination at 1250°C in an 
electrical furnace using a covered Pt/Rh crucible and subsequently melted at 1550°C for 2 h. The 
batch was melted twice in order to obtain a better glass homogeneity. The molten glass was 
poured into water and the glass frits were dried at 100°C.
 
Table 4-4: Chemical composition of sealant material 7.5 B (Ba) and 10B (Sr). 
In mol.% 
SiO
2
BaO 
SrO
MgO 
B
2
O
3
7.5 B (Ba) 
47.5 
27 
- 
18 
7.5 
10 B (Sr) 
45 
- 
27 
10 
(1) Fracture stress – sintered bar 
The determination of the fracture stress for sintered bars concentrated on the ICV-CSIC (in 
Madrid, Spain) material since previous investigations [65] indicated that for the Jülich material 
the data obtained for sintered bars are not representative for the behavior of the material in thin-
layer geometry. Bar-shaped 7.5B(Ba) and 10B(Sr) specimens were supplied by ICV-CSIC, 
Madrid. The stack representative thermal treatment was carried out on 7.5 B(Ba) at 800°C for 24 

---

Experimental 
58 
h and 800 h, on 10 B(Sr) at 750°C for 24 h and 800 h, respectively. The geometry of the 
specimen was ~45 mm × 5 mm × 4 mm. All specimen surfaces were fine-grinded with 4000-grit 
abrasive papers before the mechanical tests.
(2) Fracture stress - layers 
The so-called head-to-head joined specimens were prepared using an in-house developed sealing 
jig (
Figure