Phenomena and mechanisms of crack propagation in glass-ceramics
Phenomena and mechanisms of crack propagation in glass-ceramics
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DOI：
10.1016/j.jmbbm.2007.11.005
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发表时间：
2008-10-01
影响因子：
3.9
通讯作者：
Hoeland, W.
中科院分区：
文献类型：
--
作者：
Apel, E.;Deubener, J.;Hoeland, W.
二硅酸锂、白晶石和磷灰石微晶玻璃已成为全陶瓷口腔修复材料中最先进的框架材料。本研究的目的是研究这三种已知的玻璃陶瓷材料在经受维氏压痕后的裂纹扩展行为，并表征它们的裂纹张开曲线（δ（平均值）vs. (a - r)）。为此，采用了各种光学检查方法。采用光学显微镜对裂纹现象进行宏观观察，采用扫描电子显微镜（SEM）和原子力显微镜（AFM）等高分辨率技术对裂纹现象进行微观观察。三种微晶玻璃的裂纹模式从相当简单到更复杂，取决于材料中残余玻璃基体的数量。高强度的二硅酸锂晶体具有高度的交联，从而防止裂纹扩展。在这种材料中，裂纹仅通过残余玻璃相扩展，残余玻璃相占体积的30%-40%。白晶石和磷灰石玻璃陶瓷的玻璃含量比体积高65%以上，裂纹模式复杂得多。白晶石玻璃陶瓷的裂纹通过玻璃相和晶相传播。磷灰石玻璃陶瓷的裂纹行为与含有纳米级填料的无机-有机复合材料相似，这些填料在裂纹尖端周围被拉出。将观察到的三种微晶玻璃裂纹行为和计算得到的k -尖端值与SEVNB法测定的K-IC值进行了比较。(C) 2007 Elsevier Ltd.版权所有。
Lithium disilicate, leucite and apatite glass-ceramics have become state-of-the-art framework materials in the fabrication of all-ceramic dental restorative materials. The goal of this study was to examine the crack propagation behaviour of these three known glass-ceramic materials after they have been subjected to Vickers indentation and to characterize their crack opening profiles (delta(meas) vs. (a - r)). For this purpose, various methods of optical examination were employed. Optical microscopy investigations were performed to examine the crack phenomena at a macroscopic level, while high-resolution techniques, such as scanning electron microscopy (SEM) and atomic force microscopy (AFM), were employed to investigate the crack phenomena at a microscopic level. The crack patterns of the three glass-ceramics vary from fairly straightforward to more complex, depending on the amount of residual glass matrix present in the material. The high-strength lithium disilicate crystals feature a high degree of crosslinking, thereby preventing crack propagation. In this material, the crack propagates only through the residual glass phase, which constitutes 30%-40% by volume. Having a high glass content of more than 65% by volume, the leucite and apatite glass-ceramics show far more complex crack patterns. Cracks in the leucite glass-ceramic propagate through both the glass and crystal phase. The apatite glass-ceramic shows a similar crack behaviour as an inorganic-organic composite material containing nanoscale fillers, which are pulled out in the surroundings of the crack tip. The observed crack behaviour and the calculated K-tip values of the three types of glass-ceramics were compared to the K-IC values determined according to the SEVNB method. (C) 2007 Elsevier Ltd. All rights reserved.