Mechanical Characterization of Solid Oxide Fuel Cells and Sealants

 
 
H-P 
Glass H + 20 
wt % YSZ 
particles 
Bulk bars 
As-sintered 
4-point 
bending 
RT 
28 ± 3
[83] 
800 
~ 1 
Joined bars 
As-sintered 
RT 
22 ± 2
400 
30 ± 5 
800 
~1 
800°C for 
500 h 
RT 
47 ± 3
[49] 
[65] 
800 
~41 
 
GC-9 
BaO-B
2
O
3
-SiO
2
- 
Al
2
O
3
Bulk bars 
As-sintered 
4-point 
bending 
RT 
63 
[184] 
750 
4.5 
Annealed 
RT 
73 
Plate 
As-sintered 
Ring-on-ring 
RT 
57 ± 10 
[183] 
800 
27 ± 6 
Annealed 
RT 
56 ± 6 
800°C 
48 ± 7 
GC-18 
BaO-CaO-SiO
2
- 
Al
2
O
3
 
 
Bulk bars 
As-sintered 
4-point 
bending 
RT 
80 ± 10 
[185] 
800 
39 ± 4 
Annealed 
RT 
43 ± 3 
800°C 
30 ± 2 

---

Literature review 
52 
3.4.6.3.
Shear stress 
The shear stresses of sealant materials similar to that considered in the present work are 
summarized in 
Table
 3-9
. Schwickert [124] reported the shear stress of Glass 58, which is based 
on BaO-CaO-Al2O
3
-SiO
2
and joined with steel 1.4742. The shear stresses are in a range of 8.6-
10.5 MPa. Nielsen [186] characterized the glass NAS based on Na
2
O-Al
2
O
3
-SiO
2
with 30% 
MgO fillers using similar joined specimens. The shear stress is around 1.87 ± 0.24 MPa. The 
mechanism of these testing methods is very similar to the lap-tests, where the applied load is 
paralleled to the joined cross-section.
According to the results of KMBY sealant, the cross-bonded configuration (ISO13124, se 
Figure
 
3-14
 
(c)
) is subjected to combined shear, tensile and bending stresses, as typically occurs with 
lap-tests [187, 188]. The apparent shear strength is much lower than 71 MPa obtained by the 
torsion test [189], where a pure shear strength can be obtained. The torsion test has suggested to 
be the most reliable method to measure the pure shear strength of glass-ceramic joined 
specimens for SOFCs application. Previous works mostly focused on the (apparent) shear stress 
at room temperature. A shear test technique at high temperature was developed by Lin et al. 
[190]. Glass GC-9 was tested at room temperature and 800°C to measure shear joint stress by a 
sealant-metal jointed shear test specimen (similar as 
Figure 
3-15
 
(a)
). For sealant GC-9 with 250 
h or 500 h it appeared that shear joint strength decreases at 800°C by 17 % due to continuous 
growth of BaCrO
4
chromate.
In the current work, an improved torsion set-up has been developed for room and elevated 
temperatures. The pure shear stress of different sealants for SOFC application was investigated 
and will be discussed in the latter sections.

---

Literature review 
53 
Table 3-9: The sealants tested by different shear tests.
Glass sealant 
Specimen 
Conditions 
Test method 
Temp. 
(°C) 
Fracture 
strength (MPa) 
Ref. 
Glass 58 
BaO-CaO-SiO
2
-
Al
2
O
3
Joined 
As-sintered 
Joined shear
RT 
8.6-10.5 
[124] 
NAS 
Na
2
O-Al
2
O
3
-SiO
2
with 30% MgO 
fillers
Joined 
As-sintered 
Joined shear 
RT 
1.87 ± 0.24 
[186] 
GC-9 
BaO-B
2
O
3-
Al
2
O
3
- 
SiO
2
, CaO, La
2
O
3
ZrO
2