Department of Biomedical Materials and Engineering, Hokkaido University, Sapporo, Japan.
Dent Mater J. 2011;30(3):286-92. doi: 10.4012/dmj.2010-175. Epub 2011 May 20.
Zirconia has found wide application in dentistry because of its high mechanical strength and superior esthetic properties. However, zirconia degradation caused by phase transformation occurring in a hydrothermal environment is of concern. In the present study, phase transformation and microstructure of tetragonal zirconia polycrystal partially stabilized with yttrium oxide (Y-TZP) and alumina-toughened zirconia (ATZ) sintered at different temperatures were estimated. On grazing angle X-ray diffraction analysis, ATZ showed less phase transformation to the monoclinic phase during hydrothermal treatment and this transformation appeared to occur within a few micrometers below the surface. At a higher sintering temperature the monoclinic phase content of ATZ was found to be lesser than that of Y-TZP, indicating that the alumina in ATZ was effective in suppressing hydrothermal degradation. Examination by transmission electron microscopy and studying of electron backscatter diffraction patterns indicated that grain growth in ATZ was slightly suppressed compared with that in Y-TZP at higher sintering temperatures. The present study demonstrated the effect of adding alumina to zirconia for suppressing hydrothermal degradation and studied the effect of this addition on grain growth in zirconia.
氧化锆因其高强度和卓越的美学性能而在牙科领域得到广泛应用。然而，在湿热环境中发生的相变导致的氧化锆降解问题引起了人们的关注。本研究评估了不同温度下烧结的部分稳定氧化钇（Y-TZP）和氧化铝增韧氧化锆（ATZ）四方氧化锆多晶的相变和微观结构。在掠角 X 射线衍射分析中，ATZ 在湿热处理过程中向单斜相的相变较少，这种相变似乎发生在表面以下几微米处。在较高的烧结温度下，ATZ 的单斜相含量小于 Y-TZP，表明 ATZ 中的氧化铝在抑制湿热降解方面是有效的。透射电子显微镜检查和电子背散射衍射模式的研究表明，与 Y-TZP 相比，在较高的烧结温度下，ATZ 的晶粒生长略有抑制。本研究证明了在氧化锆中添加氧化铝以抑制湿热降解的效果，并研究了这种添加对氧化锆晶粒生长的影响。
