Kim Boo Kyung, Yun Jong Hyuk, Jung Wook Ki, Lim Chek Hai, Zhang Yu, Kim Do Kyung
Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea.
Agency for Defense Development, Daejeon, Republic of Korea.
Int J Appl Ceram Technol. 2023 Mar-Apr;20(2):856-868. doi: 10.1111/ijac.14216. Epub 2022 Sep 11.
Overall, 8-mol% yttria-stabilized zirconia (8YSZ), unlike 3YSZ, is optically transparent and stable against low-temperature degradation but has insufficient mechanical properties due to its large grain size. The influence of the grain size of 8YSZ on mechanical properties was investigated to develop an 8YSZ suitable for dental restoration. Modulation of the grain size and relative density was achieved via a two-step sintering (TSS) process, and the corresponding kinetic window was established. The conditions of TSS employed herein yielded a relative density of more than 99% while maintaining a small grain size of 0.75 μm. On the other hand, the highest biaxial strength and the highest total transmittance attained were 833 MPa and 34.6% (1-mm-thick, 39.1% for a 0.5-mm thick sample) in the TSS 8YSZ with a grain size of 1.25 μm. These results suggest that strength has improved only when grain size reduction and increased relative density are achieved at the same time. The results demonstrate that the ceramic processing method has a significant effect on the mechanical and optical properties of 8YSZ needed for dental restoration and provide a new insight that contrasts previous studies focused on the starting material.
总体而言，与3摩尔％钇稳定氧化锆（3YSZ）不同，8摩尔％钇稳定氧化锆（8YSZ）具有光学透明性，并且对低温降解具有稳定性，但由于其晶粒尺寸较大，其机械性能不足。研究了8YSZ晶粒尺寸对机械性能的影响，以开发适用于牙齿修复的8YSZ。通过两步烧结（TSS）工艺实现了晶粒尺寸和相对密度的调制，并建立了相应的动力学窗口。本文采用的TSS条件在保持0.75μm的小晶粒尺寸的同时，产生了超过99％的相对密度。另一方面，在晶粒尺寸为1.25μm的TSS 8YSZ中，获得的最高双轴强度和最高总透过率分别为833MPa和34.6％（1mm厚，0.5mm厚样品为39.1％）。这些结果表明，只有在同时实现晶粒尺寸减小和相对密度增加时，强度才会提高。结果表明，陶瓷加工方法对牙齿修复所需的8YSZ的机械和光学性能有显著影响，并提供了与以往侧重于起始材料的研究形成对比的新见解。
