Microstructure and mechanisms of fracture in corrosive enyironment in low precious metal for dental applications

牙科用低贵金属腐蚀环境中断裂的微观结构和机制

基本信息

批准号：
10450258
负责人：
NIINOMI Mitsuo
金额：
$ 3.9万
依托单位：
Toyohashi University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-10450258/
关键词：
Low precious dental alloy Ag-Pd-Cu-Au alloy Heat treatmenrt Microstructure Tensile properties Fracture toughness Fatigue characteristics Friction wear characteristics 歯科用合金破壊靱性人工だ液疲労強度摩擦磨耗 Ag-Pd-Cu-Au合金 β相強度

项目摘要

Low precious dental Ag-Pd-Cu-Au-Zn type alloys were conducted with various heat treatments, and then their static and dynamic fracture toughness, and tensile properties were investigated. Solutinizing at relatively lower temperature followed by air cooling, that is, solutionized at 1073 k for 3.6 ks followed by air cooling, we found to exhibit excellent fracture toughness and mechanical properties comparing with generally recommended heat treatment, that is, solutionizing followed by aging. Solutionizing at relatively lower temperature followed by air cooling is not only effective to improve static and dynamic fracture toughness, and tensile strength and elongation, but also simple and low cost heat treatment process because aging process can be omitted during heat treatment process. It was possible to point out that the conventional heat treatment was not always suitable for Ag-Pd-Cu-Au-Zn type alloy because in this study fracture toughness was adopted for evaluating the mechanical pe … More rformance of Ag-Pd-Cu-Au-Zn type alloy in addition to the evaluation of tensile properties, which was the only method for evaluating the mechanical performance of the materials in the dental field to date.The effect of β phase on the tensile properties and fracture toughness of Ag-Pd-Cu-Au-Zn type alloy. In that case, tensile properties and fracture toughness were evaluated with systematically changing the volume fraction of β phase. Up to the peak age condition, strength increased and elongation decreased with increasing the volume fraction of β phase. Slip bands were observed on the part far from the fracture surface for the as-solutionized alloy, but only very near the fracture surface for the aged alloy. The latter phenomenon could be due to the restriction of slip by β phase, which caused the local deformation. In the under age condition, fracture toughness decreased with increasing the volume fraction of β phase when the size of β phase was constant, while fracture toughness decreased with decreasing the diameter of β phase when the volume fraction of β phase was constant.Then, the experimental alloys with varying Cu content and without Zn were fabricated. These alloys were variously heat-treated. Then, the effects of Cu and Zn on the fracture toughness of Ag-Pd.-Cu-Au-Zn type alloy were investigated. Since the volume fraction of α_1 phase increased with increasing cu content, 0.2% proof stress decreased, but tensile strength increased due to increasing work hardering coefficient. The strength and elongation of Zn added alloy were greater and smaller, respectively comparing with Zn free alloy. The static fracture toughness of Cu added alloy was relatively greater through solutionizing at relatively higher temperature. the static fracture toughness of Zn free alloy was smaller than that of Zn added alloy. The mechanical properties of both experimental alloys were found to be equal to or greater than those of commercial alloy.The fatigue characteristics of Ag-Pd-Cu-Au-Zn type alloy conducted with various heat treatments were then investigated in the case of water quenched alloy, fatigue strength was greater with increasing solutionizing temperature because solid solution strengthening of α_2 phase increased in the low cycle fatigue life region. On the other hand, in the high cycle fatigue region, the fatigue strength was greater with decreasing solutionizing temperature because the volume fraction of α_1 phase increased and strain relief was achieved by α_1 phase. However, the volume fraction of β phase was necessary to be taken into ccount in order to increase the absolute value of fatigue strength. For the practical use of the alloy, the fatigue strength should be evaluated in the oral *nyironment. Therefore, the fatigue characteristics of the alloys conducted with various heat treatments were evaluated in the artificial saliva, and compared with those evaluated in air. The fatigue strength of as-solutinized and aged alloys was nearly the same in air and artificial saliva in the low cycle fatigue life region. In the high cycle fatigue life region, the fatigue strength of as-solutionized alloy was nearly the same in air and artificial saliva, but the fatigue strength of aged alloy was smaller in artificial saliva than in air. In the high cycle fatigue region, since the exposure time to corrosion environment was relatively longer, and the interface between β phase and matrix was preferentially corroded. Therefore, the corrosion might be severe in the aged alloy where the voltume fraction of β phase was relatively greater. The stress concentration to the corroded parts might be relatively greater. Chloride was considered to form by the reaction of Cl with Ag in this case of corrosion.It was important to investigate the fracture toughness of cast alloys because casting products were in general practically used. Fracture behavior of cast Ag-Pd-Cu-Au-Zn type alloys conducted with various heat treatments were investigated. Tensile strength of the cast alloy tended to be smaller than that of the wrought alloy. However, a decrcase in tensile strength of the cast alloy comparing with the wrought alloy was little when solution treatment was done at 1073 K followed by air-cooling. The neat treatment of solutionizing at 1073 K followed by air-cooling was judged to be proper for the cast alloy.Friction wear characteristics of Ag-Pd-Cu-Au-Zn type alloy was investigated in artificial saliva. Friction wear weight loss was the smallest in aged alloy where the volume fraction of precipitated β phase was relatively greater. The alloy solutionized at 1123 K followed by water quenching with single α_2 phase exhibit the same friction wear weight loss as that of the alloy solutionized at 1073 K followed by water quenching with α_1. phase. Friction wear weight loss of mating pin made of this alloy against the alloy conducted with solutionizing and aging was the smallest Friction wear loss of the alloys solutionized at 1073 K and 1123 K followed by water quenching was greater than that of the alloy conducted with solutionizing and aging, and was the greatest for the alloy conducted with solutionizing at 1123 K followed by water quenching. Friction coefficient between specimen and mating pin was found to relate with the friction wear weight loss of the specimen and mating pin. Less

使用各种热处理进行了低珍贵的牙齿AG-PD-CU-AU-ZN型合金，然后研究了它们的静态和动态裂缝韧性，并研究了拉伸特性。在相对较低的温度下进行空气冷却，即在1073 k的3.6 ks接和空气冷却下进行空气冷却，我们发现在相对较低的温度下，在相对较低的温度下对空气冷却，不仅可以在静态和动态较低的过程中，而且在相对较低的温度下，还可以在静态和动态的耐热过程中，而且由于在相对较低的温度下，而且在静态较低的过程中，而且在静电较低的过程中，而且由于在静态和动态的过程中，而且由于在相对较低的温度下，而且在静电较低的过程中，而且由于在静态和动态的过程中，而且由于在相对较低的温度下，而且由于在静态和动态的过程中，而且由于静态和电量的加热，因此，在相对较低的温度下，我们发现在1073 k的溶液中进行溶液，而且在相对较低的温度下进行溶液溶液。热处理过程。可以指出的是，常规的热处理并不总是适用于Ag-Pd-Cu-Au-Zn型合金合金，因为在这项研究中，采用了裂缝韧性来评估机械性PE…AG-PD-CU-AU-ZN型合金的更具性能，除了评估其效果的唯一材料的方法外，除了评估该材料的唯一方法外，还可以进行机械性能。 Ag-Pd-Cu-Au-Zn型合金的拉伸特性和断裂韧性。在这种情况下，通过系统地改变β相的体积分数来评估拉伸特性和断裂韧性。直到年龄峰值状况，强度的提高和伸长率随着β相的体积分数的增加而降低。在远离碎片表面的部分中观察到滑动带的溶剂化合金，但仅在陈年合金的碎片表面附近。后一种现象可能是由于β相限制了滑移，这导致了局部变形。在低年龄条件下，当β相的大小恒定时，断裂韧性会随着β相的体积分数的增加而降低，而当β相的体积分数恒定时，β相的尺寸持续下降，而分数韧性会降低β相的直径。然后，制造了具有不同CU含量且没有Zn的实验合金。这些合金经过各种热处理。然后，研究了Cu和Zn对Ag-Pd.-Cu-Au-Zn型合金骨折韧性的影响。由于α_1相的体积分数随CU含量的增加而增加，因此0.2％的证明应力降低，但由于工作硬化系数增加而导致拉伸强度增加。 Zn添加的合金的强度和伸长率更大和较小，分别与无锌合金相比。通过在相对较高的温度下溶解的氧化合金的静态断裂韧性相对较大。无锌合金的静态断裂韧性小于Zn添加的合金。发现两种实验合金的机械性能都等于或大于商业合金的机械性能。然后研究了用各种热处理进行的Ag-Pd-Cu-Au-ZN类型合金的疲劳特性，在水溶解的情况下进行了各种热处理，疲劳强度越来越大，疲劳强度越来越大，因为溶液在较低的溶液中增加了溶液在较低的较低型较低型疲劳中的稳定溶液增强。另一方面，在高循环疲劳区域中，由于溶液温度的降低，疲劳强度更大，因为α_1相的体积分数增加，并且通过α_1相实现应变释放。但是，为了提高疲劳强度的绝对值，必须将β相的体积分数纳入现金。为了实际使用合金，应在口服 *Nyironment中评估疲劳强度。因此，在人造唾液中评估了用各种热处理的合金的疲劳特性，并与空气中评估的合金进行了比较。在低周期疲劳寿命区域中，空气和人造唾液的疲劳强度在空气和人造唾液中几乎相同。在高循环疲劳寿命区域中，空气和人造唾液中溶剂合金的疲劳强度几乎相同，但是人工唾液中陈年合金的疲劳强度比空气中的疲劳强度小。在高循环疲劳区域中，由于暴露于腐蚀环境的时间相对较长，并且β相和基质之间的界面更有可能腐蚀。因此，在老年合金中，腐蚀可能是严重的，而β相的伏特分数相对较大。腐蚀部分的应力浓度可能相对较大。在这种情况下，认为CL与Ag的反应形成氯化物，这对于研究铸造合金的断裂韧性很重要，因为通常使用铸造产物。研究了用各种热处理进行的cast Ag-Pd-Cu-au-Zn型合金的骨折行为。铸造合金的拉伸强度比世界合金小。但是，当在1073 K进行溶液处理然后进行空冷时，与锻造合金相比，铸件合金的拉伸强度降低了。在1073 K下进行疗法的整洁处理，然后判断空气冷却是适合铸造合金的。在人工唾液中研究了Ag-Pd-Cu-Au-Zn型合金的贸易磨损特性。摩擦减肥是陈年合金中最小的，其中珍贵β相的体积分数相对较大。在1123 K处溶解的合金，然后用单个α_2相淬灭水与在1073 K下溶解的合金溶液损失相同的摩擦减肥，然后用α_1的水淬灭。阶段。用这种合金制成的摩擦磨损交配销的重量减轻与溶解和衰老进行的合金制成的摩擦是最小的摩擦磨损损失，在1073 K和1123 K下溶解的合金随后溶解的合金随后是液化的液体，其水淬火大于溶液和衰老的合金，并且是在液体上进行的，在1123 K下进行了溶液，然后是水questhing Queench。发现试样和交配引脚之间的摩擦系数与标本和配合引脚的摩擦减肥有关。较少的