Design of alumina-zirconia composites with spatially tailored strength and toughness

Design of alumina-zirconia composites with spatially tailored strength and toughness

journal article in Web of Science

en

Composites of Al2O3–5 vol.% t-ZrO2(ATZ) and Al2O3–30 vol.% m-ZrO2(AMZ) layers were designed with 3–1 connectivity to explore the effect of spatially-dependent residual stress and layer distribution on mechanical behavior. ATZ composites with "shallow" and "deep" regions of AMZ, defined relative to the distance from the surface, were fabricated. Four-point bending tests on indented 3–1 composites showed crack arrest in the first compressive AMZ layer and a fracture strength nearly independent of indent size (i.e. minimum strength); the failure occurring in the regionwith thicker outer ATZ layers ("deep" region). Region dependent crack growth resistance was measured on SEVNB specimens and compared to theoretical predictions using a fracture mechanics model. Spatially tailored constant strengths were obtained, ranging between 148 MPa and 470 MPa; the maximum value corresponding to a "shallow" region with a relatively thicker AMZ compressive layer embedded close to the tensile ATZ surface. The 3–1 design concept allows the fabrication of "deep" and "shallow" embedded regions within a unique composite architecture,thus providing a preferential path for crack propagation, opening new possibilities for design of composite structures with spatially-tailored crack growth resistance.

Composites of Al2O3–5 vol.% t-ZrO2(ATZ) and Al2O3–30 vol.% m-ZrO2(AMZ) layers were designed with 3–1 connectivity to explore the effect of spatially-dependent residual stress and layer distribution on mechanical behavior. ATZ composites with "shallow" and "deep" regions of AMZ, defined relative to the distance from the surface, were fabricated. Four-point bending tests on indented 3–1 composites showed crack arrest in the first compressive AMZ layer and a fracture strength nearly independent of indent size (i.e. minimum strength); the failure occurring in the regionwith thicker outer ATZ layers ("deep" region). Region dependent crack growth resistance was measured on SEVNB specimens and compared to theoretical predictions using a fracture mechanics model. Spatially tailored constant strengths were obtained, ranging between 148 MPa and 470 MPa; the maximum value corresponding to a "shallow" region with a relatively thicker AMZ compressive layer embedded close to the tensile ATZ surface. The 3–1 design concept allows the fabrication of "deep" and "shallow" embedded regions within a unique composite architecture,thus providing a preferential path for crack propagation, opening new possibilities for design of composite structures with spatially-tailored crack growth resistance.

Composites of Al2O3–5 vol.% t-ZrO2(ATZ) and Al2O3–30 vol.% m-ZrO2(AMZ) layers were designed with 3–1 connectivity to explore the effect of spatially-dependent residual stress and layer distribution on mechanical behavior. ATZ composites with "shallow" and "deep" regions of AMZ, defined relative to the distance from the surface, were fabricated. Four-point bending tests on indented 3–1 composites showed crack arrest in the first compressive AMZ layer and a fracture strength nearly independent of indent size (i.e. minimum strength); the failure occurring in the regionwith thicker outer ATZ layers ("deep" region). Region dependent crack growth resistance was measured on SEVNB specimens and compared to theoretical predictions using a fracture mechanics model. Spatially tailored constant strengths were obtained, ranging between 148 MPa and 470 MPa; the maximum value corresponding to a "shallow" region with a relatively thicker AMZ compressive layer embedded close to the tensile ATZ surface. The 3–1 design concept allows the fabrication of "deep" and "shallow" embedded regions within a unique composite architecture,thus providing a preferential path for crack propagation, opening new possibilities for design of composite structures with spatially-tailored crack growth resistance.

Connectivity; Composites; Residual stresses; Fracture strength; Toughness

Connectivity; Composites; Residual stresses; Fracture strength; Toughness

2015

05.01.2015

Elsevier

Holandsko

0955-2219

2015

35

631–640

10