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The distributions of fibre strength, pullout length, and fibre/matrix interface shear strength within a single fibre bundle were investigated for a 3-D woven SiC/SiC composite tensile tested at 1100 °C in air. Fibre pullout lengths were largest at the fibre bundle centre with an embrittled region of approximate width 15 μm at the perimeter. Whereas the fibre strength varied by less than a factor of 2 across the fibre bundle, the fibre/matrix interface shear strength varied by a factor of ∼23 with a minimum (100±16 MPa) at the centre and a maximum (2.25±0.21 GPa) close to the embrittled region. The minimum fibre/matrix interface shear strength required for the transition between pseudo-ductile and brittle behaviour was thus estimated to be 2.25±0.21 GPa for this composite system. [Copyright &y& Elsevier]

Abstract: Thermal diffusivity, a, and thermal conductivity, κ, between room temperature and 600K were investigated for SiC composites containing 0–50mass% of Tyranno® Siph name="sbnd" />C (SA) fibre (mean length: 394μm) hot-pressed at 1800°C for 30min under a pressure of 31MPa. The monolithic SiC specimen possessed κ of 32.1Wm−1 K−1 at room temperature; no significant changes were found for the SiC composite containing ≤20mass% of SA fibre addition. However, further increases in the amount of SA fibre to 50mass% improved κ to a maximum of 56.3Wm−1 K−1. The value of a for the SiC composite containing 40mass% of SA fibre was 0.185cm2 s−1 at room temperature and decreased to 0.120cm2 s−1 at 600K. In addition, SiC composites using 40mass% of SA fibre with a carbon interface of approximately 100nm were fabricated. The effect of this interface on a and κ was marginal. [Copyright &y& Elsevier]

Abstract: High-density and fine-grained transparent hydroxyapatite (Ca10(PO4)6(OH)2: HAp) ceramics with B2O3 and Na2O addition were fabricated using pressureless sintering and pulse-current pressure sintering between 1000 and 1100°C; the superplastic deformation of these HAp specimens was evaluated. The relative density of pure HAp compacts pulse-current pressure sintered at 1000°C for 10min under a pressure of 50MPa attained 99.9% and exhibited translucency. The tensile elongation of the pure HAp specimen, which was measured at 1000°C under a strain rate of 1.48×10−4 s−1, was as high as 364%. The relative density of HAp compacts with 3.0mol.% B2O3 addition pulse-current pressure sintered under the same conditions as those of pure HAp compacts was 98.9%, whereas the grain size was as low as 0.24μm. The elongation of HAp specimens, measured at a test temperature of 1000°C under a strain rate of 1.48×10−4 s−1, was as high as 578%. [Copyright &y& Elsevier]