Phase stability after aging and its influence on pin‐on‐disk wear properties of Ce‐TZP/Al₂O₃ nanocomposite and conventional Y‐TZP

Abstract

Recently zirconia/alumina composites have been examined by many researchers as the new generation of bearing materials in total joint replacements. In this study, the phase stability of a Ce-TZP/Al(2)O(3) nanocomposite and conventional Y-TZP after aging, and its influence on wear resistance, were investigated. Very slight phase transformation was observed in both types of ceramics 18 months after the implantation of Ce-TZP/Al(2)O(3) or Y-TZP samples into rabbit tibiae. However, Y-TZP showed marked phase transformation (approximately 80%) after aging in an autoclave (121 degrees C) for 190 h or in physiological saline at 62 degrees C for 18 months, whereas the new composite remained almost resistant to degradation. According to the results of self-pairing pin-on-disk wear tests using ceramic specimens with or without autoclave aging, the wear factor was almost the same between Ce-TZP/Al(2)O(3) samples with and without aging (6.74 +/- 0.36 x 10(-8) and 6.04 +/- 0.95 x 10(-8) mm(3)/Nm, respectively). In contrast, although non-aged Y-TZP had the lowest wear factor (4.88 +/- 0.51 x 10(-8) mm(3)/Nm) of all specimens tested, aged Y-TZP showed 10-fold greater wear than nonaged Y-TZP. The present study suggests that Ce-TZP/Al(2)O(3) nanocomposite has much greater phase stability than Y-TZP, and that its wear properties are not influenced by aging.

Degradation of dental ZrO<Sub>2</Sub>-based materials after hydrothermal fatigue. Part I: XRD, XRF, and FESEM analyses

“…An experimental material with similar composition has resulted in excellent aging resistance compared to biomedical grade yttria-stabilized zirconia 14) . In fact, the monoclinic phase remained relatively constant in NanoZr specimens (Fig.…”

“…Additionally, NanoZr contains a higher percentage of Al2O3 (alumina) that replaces part of the zirconia, as compared to the composition of 3Y-TZP materials. Initial tests with Ce-TZP/Al2O3 nanocomposite were very promising, however, other tests did not corroborate the initial data [14][15][16] . The aim of this project was to study the effect of s-LTD (simulated LTD) and thermal fatigue in artificial saliva on the chemical and structural stability of three zirconia-based dental materials.…”

The effect of adding silica to zirconia to counteract zirconia’s tendency to degrade at low temperatures

“…An accelerated aging test of zirconia is usually conducted within the range of 120°C to 140°C using an autoclave on the assumption that the material will be used for artificial joints 19,20) . Considering that the fluctuation in temperature within the oral cavity is greater than inside the extremities, our accelerated aging test was conducted under more severe conditions, using a water bath at 200°C.…”

“…The monoclinic content, an index for the degree of degradation, was 78 to 82% for the type Z specimens, except for those that broke into pieces. It has been reported that the monoclinic content of Y-TZP was found to be 81% after an accelerated aging test conducted for 190 hours at 121°C 19) and 80% for 12 hours at 134°C 20) . Those values were almost the same as those obtained for our type Z specimens after an accelerated aging test conducted for 50 hours at 200°C.…”

Effects of a convenient silica-coating treatment on shear bond strengths of porcelain veneers on zirconia-based ceramics

“…The latest zirconia-based ceramics materials, stabilized by ceria, were developed to achieve better mechanical properties than those of Y-TZP [25][26][27][28] . Ceriastabilized tetragonal zirconia/alumina nanocomposites (zirconia nanocomposites) are significantly reinforced by dispersing different nanosized particles into each crystal grain.…”