Reconciling in vivo and in vitro kinetics of the polymorphic transformation in zirconia-toughened alumina for hip joints: II. Theory
Reconciling in vivo and in vitro kinetics of the polymorphic transformation in zirconia-toughened alumina for hip joints: II. Theory
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协调髋关节用氧化锆增韧氧化铝多晶型转化的体内和体外动力学：II。
DOI：
10.1016/j.msec.2016.10.031
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
B.S. Bal
中科院分区：
文献类型：
--
作者：
G. Pezzotti;W. Zhu;M. Zanocco;E. Marin;N. Sugano;B.J. McEntire;B.S. Bal
本文提出并讨论了髋关节 ZTA 复合材料中四方到单斜 (t→m) 多晶型转变动力学的更新分析模型。该模型建立在所谓的 Mehl-Avrami-Johnson (MAJ) 转变动力学描述的基础上，它结合了两个重叠的过程：单斜晶位点的成核及其连续生长。模型中引入了对两个特定因素的依赖性，即从制造商处收到的单斜晶型的初始分数，以及 ZTA 表面上不同类型的过渡金属染色剂（例如 Ti、CoCr 和 Fe）的存在。研究这两个因素是因为在之前的现象学检索分析中发现了它们对可植入 ZTA 组件的环境稳定性的潜在作用的明确指示。单斜晶域的成核和生长是两个关键过程，它们的相互作用根据两个主要参数决定整个转变过程的实际动力学：时间和温度的表观活化能值函数以及核生长指数。这些参数明显因过渡金属污染的存在而改变，其影响被纳入模型中以解释表面退化的加剧。根据时间和温度等温或等时演化的转化动力学的一般分析描述，MAJ 描述的修改模型评估了初始单斜晶分数的影响。更新的模型已使用系统的体外实验进行了验证，并且似乎部分协调了 ZTA 髋关节组件的体外和体内数据转化差异。
In this paper, an updated analytical model for the kinetics of the tetragonal to monoclinic (t→m) polymorphic transformation in ZTA composites for hip joints is proposed and discussed. The model builds upon the so-called Mehl-Avrami-Johnson (MAJ) description of transformation kinetics, which combines two overlapping processes: nucleation of monoclinic sites, and their successive growth. Dependencies on two specific factors are introduced in the model, namely the initial fraction of monoclinic polymorph as received from the manufacturer, and the presence of different types of transition-metal stains (e.g., Ti, CoCr, and Fe) on the ZTA surface. These two factors were studied because clear indications of their potential roles on the environmental stability of implantable ZTA components were found in previous phenomenological analyses of retrievals. Nucleation and growth of monoclinic domains are two key processes whose interplay decides the actual kinetics of the overall transformation process according to two main parameters: an apparent activation energy value function of time and temperature, and a nuclei growth exponent. These parameters were clearly altered by the presence of transition metal contamination, whose effect was incorporated into the model to explain exacerbations of surface degradation. In accordance with a general analytical description of transformation kinetics for isothermal or isochronal evolutions in terms of time and temperature, the modified model of the MAJ description assesses the effect of the initial monoclinic fraction. The updated model has been validated using systematicin vitroexperiments, and appears to partly reconcilein vitroandin vivodata oft→mtransformation discrepancies in ZTA hip components.