Surface toughness of silicon nitride bioceramics: II, Comparison with commercial oxide materials
Surface toughness of silicon nitride bioceramics: II, Comparison with commercial oxide materials
复制标题
氮化硅生物陶瓷的表面韧性：二、与商业氧化物材料的比较
DOI：
10.1016/j.jmbbm.2015.08.044
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发表时间：
2016
影响因子：
3.9
通讯作者：
G. Pezzotti
中科院分区：
文献类型：
--
作者：
B. J. McEntire;Y. Enomoto;W. Zhu;M. Boffelli;E. Marin;G. Pezzotti
利用拉曼微探针辅助压痕技术，比较了关节成形术中使用的氮化硅(Si3N4)生物陶瓷和氧化铝基生物陶瓷(单相氧化铝、三氧化二铝和氧化钇增韧氧化铝，ZTA)的表面增韧行为。利用空间分辨率为1微米量级的拉曼探头，系统地研究了Vickers压痕裂纹尖端在不断增加的压痕载荷作用下扩展前后的微观应力场。同时，利用拉曼光谱对相同的微裂纹进行了裂纹张开位移(COD)曲线的监测。拉曼光谱清楚地显示了增韧Si3N4和ZTA生物陶瓷的不同机制(即分别是裂纹面桥接和ZrO2多晶型转变)，与单块氧化铝的脆性行为相比较。此外，重点是评估生物材料在水热环境中老化时这种增韧效果的有效性和持久性。在相变增韧的ZTA中，生物材料表面发生了显著程度的脆化，表面韧性因暴露在水热环境中而降低。相反，Si3N4生物材料的表面韧性值与水热作用无关。因此，裂面桥接似乎是关节置换中生物材料的一种持久的表面增韧机制。
Raman microprobe-assisted indentation, a micromechanics method validated in a companion paper, was used to compare the surface toughening behaviors of silicon nitride (Si3N4) and alumina-based bioceramics employed in joint arthroplasty (i.e., monolithic alumina, Al2O3, and yttria-stabilized zirconia (ZrO2)-toughened alumina, ZTA). Quantitative assessments of microscopic stress fields both ahead and behind the tip of Vickers indentation cracks propagated under increasing indentation loads were systematically made using a Raman microprobe with spatial resolution on the order of a single micrometer. Concurrently, crack opening displacement (COD) profiles were monitored on the same microcracks screened by Raman spectroscopy. The Raman eye clearly visualized different mechanisms operative in toughening Si3N4and ZTA bioceramics (i.e., crack-face bridging and ZrO2polymorphic transformation, respectively) as compared to the brittle behavior of monolithic Al2O3. Moreover, emphasis was placed on assessing not only the effectiveness but also the durability of such toughening effects when the biomaterials were aged in a hydrothermal environment. A significant degree of embrittlement at the biomaterial surface was recorded in the transformation-toughened ZTA, with the surface toughness reduced by exposure to the hydrothermal environment. Conversely, the Si3N4biomaterial experienced a surface toughness value independent of hydrothermal attack. Crack-face bridging thus appears to be a durable surface toughening mechanism for biomaterials in joint arthroplasty.