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Research on corrosion fatigue of dental metals

牙科金属腐蚀疲劳研究

基本信息

批准号：
05404067
负责人：
HAMANAKA Hitoshi
金额：
$ 9.6万
依托单位：
Tokyo Medical and Dental University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1995
项目状态：
已结题

项目摘要

Since corrosion and fatigue relate each other complexly in corrosion fatigue phenomenon, these factors should be investigated thoroughly.In this research project, the deformation behavior of cast dental metals was examined by a dynamic hardness tester prior to the fatigue test. As a result, titanium formed by hexagonal closed pack structure showed a different deformation behavior from usual dental alloys formed by face centered cubic structure.Secondly, a long-term immersion test for released ion detection and bimetallic corrosion test were carried out to investigate the corrosion behavior of dental metals. From the base metals whose corrosion resistance are kept by passivation like titanium, the amount of released ions was proved to increase slightly in contact with a nobler metal.With respect to the factor of specimen size, it is prove to be more influential in the mechanical property of cast titanium than in cobalt-chromium alloy. As for the influence of surface condition on fatigue property, the fatigue strength of polished specimen is considerably higher than that of as cast specimen. Taking account of human chewing cycle, the cycle of the fatigue test was estimated about 2 Hz. In the fatigue test in the air, the acceleration up to 10 Hz is proved to cause no difference. However, since the corrosion fatigue property affected much by the time factor, the test condition was set at 2Hz. From the result, dental prostheses should be designed to reduce the stress lower then 160 MPa in titanium castings and 200 MPa in cobalt-chromium castings for ten-year use at a chewing rate of 2000 times per day.

在腐蚀疲劳现象中，腐蚀与疲劳之间存在着复杂的联系，因此，对腐蚀疲劳的研究具有重要意义。结果表明，六方密排结构钛合金的变形行为与通常的面心立方结构钛合金不同。其次，通过长期浸泡离子释放检测和高温腐蚀试验，研究了牙科金属的腐蚀行为。从基体金属，其耐蚀性保持钝化钛，释放的离子量被证明是略有增加，在接触到一个高贵的金属。就试样尺寸的因素，它被证明是更影响的机械性能的铸造钛比钴铬合金。在表面状态对疲劳性能的影响方面，抛光试样的疲劳强度明显高于铸态试样。考虑到人的咀嚼周期，疲劳试验的周期估计为2Hz左右。在空气中的疲劳试验中，高达10 Hz的加速度被证明不会引起差异。然而，由于腐蚀疲劳性能受时间因素影响较大，因此将试验条件设定为2Hz。根据研究结果，在每天咀嚼2000次的情况下，钛合金铸件的应力应小于160 MPa，钴铬合金铸件的应力应小于200 MPa，以保证10年的使用寿命。