Department of Prosthodontics, Propaedeutics and Dental Materials, School of Dentistry, Christian-Albrechts University, Arnold-Heller-Straße 16, Kiel, D-24105, Germany.
J Mech Behav Biomed Mater. 2021 Aug;120:104586. doi: 10.1016/j.jmbbm.2021.104586. Epub 2021 May 19.
The aim of this study was to evaluate the effect of different sintering temperatures on biaxial flexural strength (BFS), dynamic loading, surface hardness, color reproduction, translucency, surface roughness and microstructure of zirconia with 4 mol% yttria (4YSZ) compared to zirconia with 5 mol% yttria (5YSZ).
Zirconia discs with 12 mm diameter and 1.2 mm thickness were prepared and divided into three groups (n = 53) according to different sintering temperatures (1400 °C, 1500 °C and 1600 °C). Each group was divided into five subgroups (n = 10) according to the dynamic loading procedure (none, 50%, 65%, 75% and 80%) conducted before the quasi-static BFS test and another subgroup (n = 3) used for X-ray-diffraction (XRD) microstructure analysis. BFS test and dynamic loading were performed with a piston-on-three-ball test. The surface hardness was evaluated according to Vickers. Color reproduction and translucency were measured with a spectrophotometer. A 3D laser scanning microscope was used to determine the surface roughness. Grain size measurements were performed using SEM.
A significant increase in biaxial flexural strength was observed while the sintering temperature decreased. 4YSZ had significantly higher results in biaxial flexural strength than 5YSZ. A decrease in sintering temperature resulted in a significant increase in Vickers hardness. Furthermore, 4YSZ showed significantly better color reproduction with increasing sintering temperature. At higher temperatures (1500 °C and 1600 °C), 4YSZ showed better color reproduction than 5YSZ. Compared to 4YSZ, specimens of 5YSZ exhibited significant higher translucency. Using XRD, a distorted tetragonal phase was detected in addition to regular tetragonal and cubic phases in specimens without any stress and at a low sintering temperature. The grain sizes of both materials increased with an increase in sintering temperature.
The sintering temperature has significant effects on the microstructure and thus on the mechanical and optical properties of the evaluated zirconia.
本研究旨在评估不同烧结温度对具有 4 摩尔%氧化钇（4YSZ）和 5 摩尔%氧化钇（5YSZ）的氧化锆的双轴向弯曲强度（BFS）、动态载荷、表面硬度、颜色再现性、半透明度、表面粗糙度和微观结构的影响。
制备直径为 12mm、厚度为 1.2mm 的氧化锆圆盘，并根据不同的烧结温度（1400°C、1500°C 和 1600°C）将其分为三组（n=53）。每组根据准静态 BFS 测试前进行的动态加载程序（无、50%、65%、75%和 80%）分为五个亚组（n=10），另一个亚组（n=3）用于 X 射线衍射（XRD）微观结构分析。BFS 测试和动态加载采用活塞-三球试验进行。表面硬度根据维氏硬度进行评估。颜色再现性和半透明度用分光光度计测量。使用三维激光扫描显微镜确定表面粗糙度。使用扫描电子显微镜进行晶粒尺寸测量。
随着烧结温度的降低，双轴向弯曲强度显著增加。4YSZ 的双轴向弯曲强度明显高于 5YSZ。烧结温度的降低导致维氏硬度显著增加。此外，随着烧结温度的升高，4YSZ 的颜色再现性显著提高。在较高温度（1500°C 和 1600°C）下，4YSZ 的颜色再现性优于 5YSZ。与 4YSZ 相比，5YSZ 试件的半透明度显著较高。使用 XRD，在没有任何应力且烧结温度较低的情况下，除了规则的四方相和立方相之外，还检测到扭曲的四方相。两种材料的晶粒尺寸都随着烧结温度的升高而增加。
烧结温度对评估氧化锆的微观结构以及机械和光学性能有显著影响。
