Development of Cavitation erosion resistant material using shape memory alloys

在许多工业机器中，如流体机械、水轮机和泵，与流体接触的部件表面会发生空化侵蚀。Ti - Ni形状记忆合金是一种抗冲蚀材料，具有优异的抗冲蚀性能。本研究通过在常规Ti-Ni形状记忆合金中加入第三元素，改变其力学性能和转变温度，对Ti-Ni基形状记忆合金进行了空化侵蚀试验。通过扫描电镜观察，讨论了不同第三组分的抗冲蚀性能。研究发现，与核电站管道用的SUS304奥氏体不锈钢相比，每一种试验材料的潜伏期都要长5 ~ 20倍。一般来说，碳钢的耐蚀性与硬度有很好的相关性。然而，Ti-Ni基形合金与硬度的相关性不明显。认为材料表面的缺陷影响了材料的耐蚀性。测量了初始缺陷的密度，随着初始缺陷密度的增加，材料表面的耐蚀性降低。但是，如果只考虑初始缺陷的密度，这种相关性还不够好。认为缺陷的密度和扩散速度都可能影响腐蚀。我们用扫描电子显微镜测量了侵蚀面积的速率。我们将耐蚀性归纳为侵蚀面积扩展速率与孔隙等初始缺陷密度乘积的函数。另一方面，硬度与侵蚀面积的扩展速度有一定的关系。由此得出，耐蚀性与初始缺陷密度与材料硬度的乘积具有良好的相关性，且易于测量。因此，Ti-Ni基形状记忆合金的耐蚀性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