Development of Titanium Alloys for Dental Castings

钛合金具有优良的耐腐蚀性和良好的生物相容性，在医疗和牙科领域有着广阔的应用前景。牙科材料要求精密和复杂，因此精密铸造是牙科合金不可缺少的技术。然而，钛（一种非常活跃的金属）的牙科铸造涉及一些有待解决的问题，例如，高温下的氧化、大气元素的吸收以及与模具材料的反应。牙科钛合金铸造的研究很多，主要从模具材料方面进行。而钛的熔点较高，约为1670 ℃，是造成铸件缺陷的主要因素之一。要解决这一问题，合金化的改进被认为起着重要作用。合金化不仅能有效地降低合金的熔化温度，而且能提高合金的力学性能。本研究的目的是开发具有良好机械性能的钛合金， ...更多信息 钛合金材料的力学性能分散性大是开发牙科铸造用新型钛合金的首要问题。因此，研究了影响纯钛铸件力学性能的因素。钛锭的种类、熔炼气氛和铸件中的杂质是影响钛锭性能的主要因素。结果，获得了关于影响因素的基本数据-所需真空度、钛等级、杂质元素的量。在此基础上，对Ti-Zr和Ni-Ti合金进行了研究。钛锆合金也显示出良好的生物相容性，钛锆合金表面在人工生物液体中的成分变化与钛表面略有不同。牙科用Ni-Ti合金的铸造比纯钛容易，由于Ni-Ti合金的熔点约为1300 ℃，比纯钛低近400 ℃，可以用常规方法铸造而不损失形状记忆效应和超弹性的特殊性能。少

Since titanium alloys show excellent corrosion resistance and good biocompatibility, they are expected to be applied in the medical and dental fields. Precision and complication are required in dental materials, therefore, precise casting is an indispensable technique for dental alloys. However, dental casting of titanium, a very active metal, involves some problems to be solved, e.g., oxidation at high temperatures, absorption of atmospheric elements, and reaction with mold materials. Many researches for dental casting of titanium have been performed, mainly from the aspect of mold materials. While high melting point of titanium, about 1670 ﾟC, is one of the main factors of casting defects. To solve this problem, the improvement in alloying is thought to play an important role. Alloying is effective not only to lower the melting temperature but also to improve the mechanical properties. The purpose of this study was to develop the titanium alloys showing good mechanical properties as … More well as suitable for dental casting.The first problem in developing new titanium alloys for dental casting was the large scatter in mechanical properties caused by titanium materials. Therefore, the factors influencing the mechanical properties of pure titanium castings were investigated. The factors were the kinds of titanium ingots, the atmosphere in melting, and the impurities in the castings. As a result, basic data on the influential factors - required vacuum degree, titanium grade, amounts of impurity elements - were attained. Based on the findings, researches on Ti-Zr and Ni-Ti alloys were performed. Ti-Zr alloys also show good biocompatibility; the compositional change of Ti-Zr alloy surface in an artificial bioliquid was somewhat different from titanium surface. Dental casting of Ni-Ti alloy was easier than titanium; it could be cast without losing the special properties of shape memory effect and superelasticity by a conventional method because the melting point of Ni-Ti alloy were about 1300 ﾟC, nearly 400 ﾟC lower than titanium. Less