Sharif Digital Repository

The structural integrity of the sealant is critical for the reliability of solid oxide cells (SOCs) stacks. In this study, elastic modulus (E), hardness (H) and fracture toughness (KIC) of a rapid crystallizing glass of BaO–CaO–SiO2 system termed “sealant G” are reported as determined using an indentation test method at room temperature. A wide range of indentation loads (1 mN–10 N) was used to investigate the load-dependency of these mechanical properties. Values of 95 ± 12 GPa, 5.8 ± 0.2 GPa and 1.15 ± 0.07 MPa m0.5 were derived for E, H and KIC using the most suitable indentation loads. An application relevant annealing treatment of 500 h at 800 °C does not lead to a significant change of... 

The structural integrity of the sealant is critical for the reliability of solid oxide cells (SOCs) stacks. In this study, elastic modulus (E), hardness (H) and fracture toughness (KIC) of a rapid crystallizing glass of BaO–CaO–SiO2 system termed “sealant G” are reported as determined using an indentation test method at room temperature. A wide range of indentation loads (1 mN–10 N) was used to investigate the load-dependency of these mechanical properties. Values of 95 ± 12 GPa, 5.8 ± 0.2 GPa and 1.15 ± 0.07 MPa m0.5 were derived for E, H and KIC using the most suitable indentation loads. An application relevant annealing treatment of 500 h at 800 °C does not lead to a significant change of... 

A torsion test recently implemented for solid oxide fuel cell sealant materials is analyzed as a method for measuring the shear strength of sealant for solid oxide fuel cells. The finite element method is used to simulate the stress distribution in the hourglass-shaped steel specimens with intermediate sealant layer with different specimen's dimensions and configurations. Also, it is analyzed how stress concentration changes if the sealant does not completely fill the gap or is squeezed out of gap. The reduction of seal thickness to outer radius ratio results in an increase in stress concentration at the outer edge of sealant. The developed specimens with a hollow halve steel plate as well... 

Assessment of mechanical properties of glass/metal joints is a challenging process, especially when the application relevant conditions of the joints have to be considered in the test design. In this study, a finite element method (FEM) is implemented to analyze a torsional shear strength test designed for glass-ceramic/steel joints aiming towards solid oxide fuel/electrolysis cells application. Deviations from axial symmetry of the square flanges (ends) of respective hourglass-shaped specimens and also supporting and loading sockets of the test set-up are included in the model to simulate conditions close to reality. Undesirable tensile stress and also shear stress concentration appear at... 

The structural integrity of the sealant material is critical for the reliability of solid oxide fuel/electrolysis stacks. In the current study, a torsion test is implemented to evaluate and compare its shear strength with a partially crystallized glass sealant at room- and operation relevant high-temperatures. Hourglass-shaped specimens with different configurations of hollow- and full-halves are utilized for testing. The fracture surfaces are visualized via optical microscopy and complementary scanning electron microscopy. In addition, cyclic loading is used to investigate potential subcritical crack growth effects in the sealants. Both, the specimens with a hollow-half as well as the ones... 

The conventional relations for calculating the fracture stresses consider only elastic deformation but ignore viscoelastic and viscoplastic behaviors. Measuring the joining strength of a composite glass sealant-metallic interconnect specimen at solid oxide cell application relevant at high temperatures is a case where such effects can become significant. In the current study, three-point and four-point bending test results were analyzed using the finite element method (FEM) to assess systematic and random errors. It is shown that plastic deformation of the steel interconnect material at high temperature, although having a large effect on the stress distribution in the... 

Fibrin sealant and platelet gels are human blood-derived, biodegradable, non toxic, surgical products obtained by mixing a fibrinogen concentrate or a platelet rich plasma with thrombin, respectively. Fibrin sealant is now a well known surgical tool increasingly used to stop or control bleeding, or to provide air and fluid tightness in many surgical situations. Platelet gels are newly developed preparations that are of specific interest because they contain numerous physiological growth factors and cytikines that are released upon the activation of blood platelets by thrombin. These growth factors, including PDGF, TGF-β1, BMP, and VEGF have been shown to stimulate cell growth and...