Ceramic fillers in a glass contribute to strength and fracture toughness.
A family of glass/ceramic composite materials has been investigated for use as sealants in planar solid oxide fuel cells. These materials are modified versions of a barium calcium aluminosilicate glass developed previously for the same purpose. The composition of the glass in mole percentages is 35BaO + 15CaO + 5Al2O3 + 10B2O3 + 35SiO2. The glass seal was found to be susceptible to cracking during thermal cycling of the fuel cells.
In preparation for experiments, panels of the glass/ceramic composites were hotpressed and machined into test bars. Properties of the test bars, including fourpoint flexure strength, fracture toughness, modulus of elasticity, and density were determined. Four-point flexure strength and fracture toughness were found to increase with alumina or 3YSZ content (see figure). For the same mole percentage of ceramic, the increases in strength and fracture toughness were greater in the composites containing alumina than in the composites containing 3YSZ.
This work was done by Narottam P. Bansal of Glenn Research Center and Sung R. Choi of the University of Toledo. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs. com/tsp under the Materials category.
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Refer to LEW-17905-1.