Manufacturing and deformation behavior of alumina and zirconia helical springs at room temperature

Abstract

Ceramic helical springs with identical dimensions were produced by hard machining from alumina, alumina toughened zirconia (ATZ), and tetragonal zirconia polycrystals (TZP) stabilized with different oxides. According to the results of the spring constant determination under deformation rates of 3 mm/min, the deformation behavior of all ceramic springs obeys to Hook's law. However, variation of the deformation rate, tests under constant load, and spring recovery behavior revealed differences in the deformation behavior of alumina, TZP, and ATZ springs. Alumina springs exhibited time-independent deformation in all tests. In contrast, anelastic deformation at room temperature was demonstrated in all springs containing TZP. This deformation is completely reversible over a period of several days. Anelastic behavior is particularly pronounced in Y-TZP springs, whereas Ce-TZP springs exhibit comparatively very low but still reliably detectable anelasticity. Oxygen vacancies in the TZP ceramic are considered the most likely explanation for the anelastic behavior of TZP springs at room temperature.

Microplastic response of 2PP‐printed ceramics

“…At room temperature, as in the presented work, ceramic components may show observable creep due to diffusion of oxygen vacancies 23 . However, due to low diffusion rates, such behavior typically occurs on time scales of hours, that is, significantly longer than those used in this study 24 . Thus, diffusive transport is unlikely to be the origin for the here‐observed mechanical dissipation behavior.…”

“…23 However, due to low diffusion rates, such behavior typically occurs on time scales of hours, that is, significantly longer than those used in this study. 24 Thus, diffusive transport is unlikely to be the origin for the here-observed mechanical dissipation behavior. Furthermore, we exclude a stress-induced phase transition toward the low-temperature monoclinic YSZ phase suggested by molecular dynamics simulations as the connected volume change is expected to be positive, 25 whereas the observed creep-like behavior shows compressive displacement accumulation of the microblocks.…”