陶瓷股骨头应力分布的有限元分析及制备工艺研究

发布时间：2018-12-17 14:17

【摘要】：由于疾病、运动创伤和老龄化等因素导致的关节病变和损伤严重影响了人们的生活质量，需要借助人工关节置换来恢复功能。本文第一部分通过建立人工股骨头—颈的有限元模型，应用三维非线性有限元分析方法模拟了氧化锆陶瓷股骨头—钛合金股骨柄的应力分布情况，通过改变股骨头假体模型的各种设计参数，分析了股骨头的最大等效应力及分布特征。氧化锆陶瓷股骨头应力分布云图显示，氧化锆陶瓷股骨头应力分布与其临床断裂面形貌特征完全符合。研究表明，随着静载荷增大，陶瓷股骨头的最大等效应力也随之增大；随着锥孔锥度增大，陶瓷股骨头的最大等效应力呈现先降低后升高的趋势变化；随着颈干角增大，陶瓷股骨头的最大等效应力随之减小；随着陶瓷股骨头直径的增大，，陶瓷股骨头的最大等效应力值逐渐减小。以上有限元模型的分析结果，不仅为陶瓷股骨头的结构设计、组织优化和材料选择提供了十分有价值的实验依据，同时，也为陶瓷股骨头的临床应用提出了有用的参考。随着先进材料制造工艺的不断发展，陶瓷注射成型技术作为一种新型的近净成型技术，已受到广大材料专家的普遍关注并在精密陶瓷生产行业得到逐渐应用。陶瓷注射成型技术包括喂料制备，注射成型，脱脂和烧结四个主要步骤，然而，脱脂和烧结阶段是该技术实施过程中控制最难和耗时最长的关键环节。本文第二部分基于ZrO_2陶瓷粉末注射成型技术的应用，探讨了该技术在氧化锆陶瓷股骨头生产过程中的关键环节，特别深入研究了低温热脱脂过程及机理。以蜡基ZrO_2陶瓷粉末注射喂料的热分析规律为依据，分析了蜡基喂料的热脱脂过程，探讨了蜡基喂料的热脱脂机理。通过对热脱脂前后ZrO_2陶瓷粉末注射成型球坯的重量损失、尺寸收缩、外观缺陷和微观组织形貌的分析评估，着重探讨了蜡基ZrO_2陶瓷粉末注射成型球坯热脱脂过程中存在的主要缺陷和成因。研究表明，流蜡、鼓泡和开裂等热脱脂缺陷主要发生在低温脱脂阶段。然后，结合“失重率控制”和“定点等温控制”的热脱脂思路，给出了优化蜡基ZrO_2陶瓷粉末注射成型球坯热脱脂工艺的基本原则。最后，对传统热脱脂工艺进行了改进和优化。在不延长总脱脂时间的前提下，显著提高了蜡基ZrO_2陶瓷注射成型球坯的脱脂合格率，并且烧结获得了致密的ZrO_2陶瓷球头。
[Abstract]:Joint diseases and injuries caused by diseases, sports injuries and aging seriously affect people's quality of life, and need artificial joint replacement to restore their functions. In the first part of this paper, by establishing the finite element model of artificial femoral head and neck, the stress distribution of zirconia ceramic femoral head and titanium alloy femur handle is simulated by using three-dimensional nonlinear finite element method. By changing the design parameters of the femoral head prosthesis model, the maximum equivalent stress and distribution characteristics of the femoral head are analyzed. The stress distribution of the femoral head of zirconia ceramic shows that the stress distribution of the femoral head of zirconia ceramics is in good agreement with the morphology of its clinical fracture surface. The results show that the maximum equivalent stress of ceramic femoral head increases with the increase of static load, and the maximum equivalent stress of ceramic femoral head decreases first and then increases with the increase of cone taper. The maximum equivalent stress of ceramic femoral head decreases with the increase of neck shaft angle, and decreases with the increase of ceramic femoral head diameter. The analysis results of the above finite element model not only provide a valuable experimental basis for the structural design, tissue optimization and material selection of ceramic femoral head, but also provide a useful reference for the clinical application of ceramic femoral head. With the continuous development of advanced material manufacturing technology, ceramic injection molding technology, as a new type of near-net molding technology, has been widely concerned by material experts and gradually applied in the precision ceramic production industry. Ceramic injection molding technology includes four main steps: feed preparation, injection molding, degreasing and sintering. However, degreasing and sintering stage are the most difficult and time-consuming key steps in the implementation of the technology. In the second part, based on the application of ZrO_2 ceramic powder injection molding technology, the key link of the technology in the production of zirconia ceramic femoral head is discussed, especially the process and mechanism of low-temperature thermal degreasing. Based on the thermal analysis rule of wax-based ZrO_2 ceramic powder injection feed, the thermal degreasing process of wax-based feed was analyzed, and the mechanism of wax-based feed thermal degreasing was discussed. The weight loss, size shrinkage, appearance defect and microstructure of ZrO_2 ceramic powder injection molding were analyzed and evaluated before and after thermal degreasing. The main defects and causes of thermal degreasing of wax-based ZrO_2 ceramic powder injection molding ball billet were discussed. The results show that the thermal degreasing defects, such as wax flow, bubbling and cracking, mainly occur at the stage of low temperature degreasing. Then, combined with the ideas of "weight loss rate control" and "fixed-point isothermal control", the basic principles for optimizing the thermal degreasing process of wax-based ZrO_2 ceramic powder injection molding ball billet were given. Finally, the traditional thermal degreasing process was improved and optimized. On the premise of not prolonging the total degreasing time, the degreasing qualification rate of wax-based ZrO_2 ceramic injection molding ball was improved significantly, and the compact ZrO_2 ceramic ball head was obtained by sintering.
【学位授予单位】：苏州大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R318.01

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