Development of Cavitation erosion resistant material using shape memory alloys

在流体机械、水轮机、泵等工业机械中，与流体接触的部件表面都存在气蚀现象。Ti-Ni形状记忆合金是一种具有优良抗冲蚀性能的材料，本文通过在常规Ti-Ni形状记忆合金中添加第三种元素，改变合金的力学性能和相变温度，对Ti-Ni基形状记忆合金进行了空蚀试验。通过扫描电子显微镜观察，讨论了不同第三组分的抗冲蚀性能。结果表明，与核电站等管道用奥氏体不锈钢SUS 304相比，各试验材料的孕育期均较长，约为后者的5 ~ 20倍。然而，钛镍基形状备忘录 关于我们 合金的抗冲蚀磨损性能与硬度之间没有很好的相关性，认为材料表面的缺陷影响了材料的抗冲蚀磨损性能。测量了材料表面初始缺陷密度，发现随着初始缺陷密度的增加，材料的抗冲蚀性能下降。然而，仅考虑初始缺陷的密度的相关性是不够好的。认为不仅缺陷的密度，而且扩展速率也会影响腐蚀。我们用扫描电子显微镜测量侵蚀面积的速率。我们总结了抗侵蚀性作为侵蚀区域的扩展速率和初始缺陷密度（如孔隙）的乘积的函数。另一方面，硬度与侵蚀区的扩展速率有一定的关系。结果表明，Ti-Ni基形状记忆合金的耐冲蚀性能与初始缺陷密度和材料硬度的乘积有很好的相关性，且易于测量，因此，Ti-Ni基形状记忆合金的耐冲蚀性能受初始缺陷密度和材料硬度的共同影响。少

Cavitation erosion occurs on the surface of the components that contact the fluid in many industrial machines such as the fluid machineries, hydraulic turbines and pumps. We have reported that the Ti Ni shape memory alloy is one of the erosion resistant materials, which shows an excellent erosion resistance.In this study, the cavitation erosion tests of Ti-Ni base shape memory alloy was carried out with the addition of the third element to the regular Ti-Ni shape memory alloy to change mechanical properties and the transformation temperature. The erosion resistance with various third components was discussed through the observation by a scanning electron microscopy. It was founded that every test materials indicate a long incubation period of 5 to 20 times that as compared with austenitic stainless steel SUS304 used for the pipe of the nuclear power plants and so on. In general, erosion resistance of carbon steels has a good correlation with hardness. However, the Ti-Ni base shape memo … More ry alloys did not show a good correlation with hardness.It was thought that the defect on the surface of the material influenced the erosion resistance. The density of initial defects was measured, and the erosion resistance is decreased with the increased density of the initial defects on the material surface. However, the correlation is not good enough for only taking account of the density of the initial defect. It was thought that not only the density of defects but also the spreading rate may influence the erosion. We measured the rate of the eroded area with a scanning electron microscopy. We summarized the erosion resistance as a function of the product of the spreading rate of the eroded area and the initial defect density such as pores. On the other hand, there is some relation between hardness and the spreading rate of the eroded area. Therefore, it is obtained that there is a good correlation between the erosion resistance and the product of the initial defect density and material hardness, which can be measured easily.Therefore, it was concluded that the erosion resistance of Ti-Ni base shape memory alloy was influenced by both initial defect density and material hardness. Less