Abstract
Ceramic bars of zirconia toughened–alumina composites were fabricated by pressureless sintering in air at 1450 °C for 4 h. Composite samples were fabricated with two different compositions: zirconia with 60 vol.% alumina (ZT60A) and zirconia with 40 vol.% alumina (ZT40A). Average four-point-bend strengths for the ZT40A and ZT60A were 480 ± 45 MPa and 410 ± 120 MPa, respectively. Three-layered sandwich structures were fabricated by joining two bars of sintered ZT60A with a sintered ZT40A bar. High-temperature plastic joining was accomplished at 1350 °C at a strain rate of 5 × 10 −6 s −1 and a compressive stress ranging from 30–40 MPa. Bend tests conducted on the layered structure exhibited average strengths of 707 ± 81 MPa. Strength enhancements for the multilayered structure were higher than those predicted by stress analysis. Stress enhancements were compared with the residual stresses measured in the layered sample using X-ray micro-diffraction at the Advance Photon Source (APS). Scanning electron microscopy (SEM) was also conducted to identify the location of failure causing flaws.
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