Residual stresses generated during joining of dissimilar alumina-zirconia composites by plastic deformation and its implications on mechanical properties

摘要

Ceramic bars of zirconia toughened-alumina composites were fabricated by pressureless sintering in air at 1450℃ for 4h. 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±45MPa 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℃ at a strain rate of 5×10~(-6)s~(-1) and a com-pressive 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.