High-temperature tensile ductility in TZP and TiO2-doped TZP

Criterion for High Temperature Failure and Grain Boundary Chemistry in Superplastic TZP

“…The temperature and strain rate dependences on the (b) at an initial strain rate of 1:3 Â 10 À4 s À1 at temperatures between 1473 and 1823 K. 13) high temperature tensile ductility in TiO 2 -added TZP were phenomenologically explained from the viewpoint of the grain size at the time of failure as a parameter of limitation of an accommodation process for superplastic flow. 13) On the other hand, a first principle molecular orbital calculation revealed that the tensile elongation to failure in ceramics correlates well with bond overlap population between anions and cations, which corresponds to covalent bond strength between atoms. 14,15) The change in the chemical bonding strength at grain boundaries must dominantly influence grain boundary diffusion and bond strength at the grain boundaries, and thus seems to be an important factor to determine the plastic flow in superplastic ceramics.…”

“…Figure 1 shows a comparison of stress-strain curves in (a) 2.5 mol% Y 2 O 3 -stabilized TZP and (b) TZP-5 mass%(7.8 mol%) TiO 2 under an initial strain rate of 1:3 Â 10 À4 s À1 at temperatures between 1473 and 1823 K. 13) In TZP, the flow stress is reduced as the temperature increases, and the elongation to failure becomes larger at higher temperatures up to 1823 K. The flow stress in TZPTiO 2 also decreases with increase in temperature, but the elongation to failure in TZP-TiO 2 decreases with increase in temperature above 1673 K. This fact indicates that the elongation to failure is not a simple function of the flow stress. The temperature and strain rate dependences on the (b) at an initial strain rate of 1:3 Â 10 À4 s À1 at temperatures between 1473 and 1823 K. 13) high temperature tensile ductility in TiO 2 -added TZP were phenomenologically explained from the viewpoint of the grain size at the time of failure as a parameter of limitation of an accommodation process for superplastic flow. 13) On the other hand, a first principle molecular orbital calculation revealed that the tensile elongation to failure in ceramics correlates well with bond overlap population between anions and cations, which corresponds to covalent bond strength between atoms.…”

“…For comparison, the stress-strain curve in Y-TZP at 1673 K is also plotted for comparison. 13) TiO 2 and GeO 2 co-doped TZP exhibits huge tensile elongation to failure at high temperatures in comparison with TZP, but the elongation to failure takes a maximum value at the intermediate temperature. On the other hand, the flow stress at early stage of deformation with the strain of less than 10%, in which the grain growth effect can be neglected, is reduced with the increase in the temperature.…”

Effect of Small Amount of Insoluble Dopant on Tetragonal to Monoclinic Phase Transformation in Tetragonal Zirconia Polycrystal

“…5) We have also developed an insert material for joining of zirconia dental bridge with a composition of 7.7 mol%TiO 2 -doped TZP, 6,7) by applying enhanced superplasticity in TiO 2 -doped TZP explained from the balance between the grain size and the increased accommodation length for the stress concentration by diffusion. [8][9][10] Thus, it is important to investigate the effect of second phase or dopant on some properties in zirconia bioceramics.…”

Effect of Titania Doping on Phase Stability of Zirconia Bioceramics in Hot Water

“…5,6) This method is an application of enhanced superplasticity in TiO 2 -doped TZP, 7) which is explained from the balance between the grain size and the increased accommodation length for the stress concentration by diffusion. 8,9) It is well known that zirconia ceramics shows the martensitic phase transformation preferentially at the surface of tetragonal zirconia. It has been shown that tetragonal to monoclinic (t-m) transformation at the surface of zirconia ceramics is accelerated by the presence of water molecules in the environment.…”