Studies on the Precision Casting of NiTi Shape Memory Alloy

Ni-Ti合金是由镍和钛以几乎相等的原子比组成的合金，具有独特的力学性能，如形状记忆效应和超弹性。它们不仅可用于工业用途，而且可用于医疗和牙科用途。由于这些合金的制造是如此困难，精密铸造工艺在需要复杂形状或高尺寸精度的情况下是有用的。然而，在钛合金的铸造中存在很多问题，因为熔融钛合金与气氛和耐火模具都是如此活泼。本文对NiTi合金的精密铸造进行了研究，在我们研制的铸造机上，通过在高真空中加热模具来排除模具中的气体，减少了金属的氧化，大大减少了合金与模具之间的反应。NiTi合金可以铸造而不会失去其重要性能，即使使用商业牙科磷酸盐结合二氧化硅包埋剂， ...更多信息 新台币。合金的力学性能和铸造性能在牙科领域具有实用价值，加入Au后，合金的耐腐蚀性能明显提高，Ni离子的析出量明显降低。对NiTi合金在人工关节中的应用进行了磨损和腐蚀试验。NiTi合金股骨头球与hdp髋臼杯的匹配性优于市售股骨头和髋臼杯。NiTi合金有望成为一种有前途的人工关节材料。在阳极极化曲线上，Ni-Ti合金的击穿电位高于Ni-Cr和Co-Cr合金。Ni-Ti合金在0.9%NaCl溶液中的Ni阳离子溶出量远低于市售牙科合金。热处理条件对NiTi合金的性能有很大的影响，本研究结果对工业、医疗和牙科等领域有一定的参考价值。少

Ni-Ti alloys which consist of nickel and titanium in nearly equal atomic proportions possess unique mechanical properties, such as shape memory effect and super-elasticity. They are expected a lot of application not only for industrial use but also medical and dental use. As the fabrication of these alloys is so difficult, the precision casting processes are useful where intricate shapes or high dimensional accuracy are required. However, there are a lot of problems in the casting of titanium alloys, because the molten titanium alloys are so reactive, both with the atmosphere and the refractory mold. In this study, the precision casting of NiTi alloys were studied.In the casting machine which we developed, as gas in the mold was removed by heating the mold in the high vacuum, oxidation of metal was less and reaction between alloy and mold was much decreased. NiTi alloys could be cast without losing their important properties, even with commercial dental phosphate bonded silica investme … More nt. The mechanical properties and castability of these alloys are practical and useful in the dental field.The corrosion resistance was much improved by the addition of Au, and the levels of Ni ion concentration released from the alloys decreased considerably compared with those of the original Ni-Ti alloys. The application of NiTi alloy to artificial joints was examined in wear and corrosion tests. The better fitness between NiTi alloy head ball and the hdp socket was obtained than that of commercial femoral head and socket. NiTi alloy is expected to be a promising candidate for artificial joint materials. Ni-Ti alloys showed higher breake down potential in anodic polarization curves than those of commercial Ni-Cr and Co-Cr alloys. The amount of Ni cations dissolved from Ni-Ti alloys in 0.9% NaCl solution is by far lower than those from commercial dental alloys. The properties NiTi alloys were much influenced by the heat treatment condition.The results obtained in this study seem to be useful for industrial, medical and dental field. Less