Residual stress effects and t ? m transformation in ion-implanted yttria-stabilized zirconia

Abstract

Ion-beam treatment affects the near surface region of ceramic materials and is a potential technology in altering the surface microstructure and properties, in this study, a preliminary surface modification in yttria-stabilized zirconia was investigated through the employment of ion implantation. Fracture toughness and hardness were measured and evaluated by the indentation method for specimens implanted by direct As + bombardment. With the aid of residual stress measurement by X-ray diffraction, the properties of the implanted specimens can be related to the residual compressive stress induced by irradiation effects. Thermal stability of zirconia is improved due to the suppression of the tetragonal to monoclinic transformation in the presence of the residual compressive stress.

Effect of ionizing radiation on mechanical properties and translucency of monolithic zirconia

“…These results indicate that a tetragonal to cubic ( t–c ) transformation took place after the specimens were exposed to 70 Gy irradiation and some theories may explain the mechanisms behind this transformation. A significant effect of ionizing irradiation on zirconia microhardness was reported as a result of residual compressive stresses generated by t – c surface phase transformation, confirming the findings of the present study (Duh & Wu, ). Besides the t–c transformation, the stress field associated with those changes can escalate to irradiation “defects” due to localized vacancies developed, as previously reported in a study investigating 10 mol% yttria‐stablized zirconia (Bekale et al, ).…”

“…(Fabris, Paxton, & Finnis, ; Guo, ; Karapetrova et al, ) For example, it was observed that by controlling the concentration of oxygen vacancies tetragonal phase can be stabilized at room temperature. (Duh & Wu, ) Therefore, monoclinic‐to‐tetragonal, and tetragonal‐to‐cubic phase transformations can be triggered by increasing the oxygen vacancy concentration. (Badwal, Bannister, & Hannink, ) This correlation between oxygen vacancy and the phase stability of zirconia has also been shown in other studies (Eichler, ; Guo, ).…”

Designing functionally graded materials with superior load-bearing properties

“…This is because the glass penetrates the grain boundaries and gradually separates the ceramic grains, leading to an increase in volume accompanied by localized compressive stresses at the surfaces of graded materials. We are currently conducting residual stress measurements of graded structures by micro-x-ray analysis using the “sin 2 ψ ” technique [48, 49]. Preliminary results have revealed no significant residual stresses at the graded glass-zirconia surface or in the center of the zirconia core, suggesting that the strengthen effect is indeed induced from the surface grading.…”