The heat capacities, thermal-expansion coefficients, thermal and electrical conductivities of Nb 2 AlC (actual Nb:Al:C mole fractions: 0.525 Ϯ 0.005, 0.240 Ϯ 0.002, and 0.235 Ϯ 0.005, respectively), Ti 2 AlC and (Ti, Nb) 2 AlC (actual Ti:Nb:Al:C mole fractions: 0.244 Ϯ 0.005, 0.273 Ϯ 0.005, 0.240 Ϯ 0.003, and 0.244 Ϯ 0.005, respectively) were measured as a function of temperature. These ternaries are good electrical conductors, with a resistivity that increases linearly with increasing temperatures. The resistivity of (Ti, Nb) 2 AlC is higher than the other members, indicating a solid-solution scattering effect. The thermal-expansion coefficients, in the 25 ЊC to 1000 ЊC temperature range, are comparable and fall in the narrow range of 8.7 to 8.9 ϫ 10 Ϫ6 K Ϫ1 , with that of the solid solution being the highest. They are all good conductors of heat, with thermal conductivities in the range between 15 to 45 W/m K at room temperature. The electronic component of the thermal conductivity is the dominant mechanism at all temperatures for Nb 2 AlC and (Ti, Nb) 2 AlC. The conductivity of Ti 2 AlC, on the other hand, is high because the phonon contribution to the conductivity is nonnegligible.M.W. BARSOUM, Professor, I. SALAMA, and T. EL-RAGHY are with
Biomorphic silicon carbide (bioSiC), a novel porous ceramic derived from natural wood precursors, has potential applicability at high temperatures, particularly when rapid temperature changes occur. The thermal conductivity of bioSiC from five different precursors was experimentally determined using flash diffusivity and specific heat measurements at temperatures ranging from room temperature to 1100°C. The results were compared with values obtained from object‐oriented finite‐element analysis (OOF). OOF was also used to model and understand the heat‐flow paths through the complex bioSiC microstructures.
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