基于 NiTi 温敏形状记忆纳米结构调控的润湿性研究

NiTi 合金是常见的形状记忆合金,有着良好的形状记忆效应、超弹性、耐腐蚀性和生物相容性,在生物医疗、航空航天和微机电等领域有着广泛的应用。 目的 研究 NiTi 合金表面不同纳米级结构的润湿性能,改善 NiTi 合金在工作环境下的磨损情况,提高 NiTi 合金的使用寿命。 方法 使用分子动力学方法模拟周期性边界条件下 NiTi 合金的形状记忆效应,研究在不同温度下 NiTi 合金原子的微观结构演化;同时基于 NiTi 合金温度响应下不同的微观结构,建立液滴静态接触角仿真,研究 NiTi 合金表面在不同微观结构下的润湿性能。 结果 发现 NiTi 合金在不同温度响应下发生相变,从而使 NiTi 合金的表面原子排列发生改变,展示了温度诱发 NiTi 合金的相变和逆相变行为以及在原子尺度下的微观结构演化,再以不同温度响应下发生相变和逆相变的 NiTi 合金表面作为基底,发现其表面的润湿性也发生了改变和恢复。 结论 NiTi 合金随温度响应发生相变,微观结构发生改变,其表面的润湿性能也发生改变;而且 NiTi 合金随温度逆相变,微观结构恢复到初始状态,其表面润湿性也能随之恢复到初始状态;NiTi 合金在相变过程中的奥氏体和马氏体含量会影响 NiTi 合金表面润湿性能,因此能够通过温度进行 NiTi 合金表面在微观结构下润湿性的自适应调控。

Wettability Study Based on the Regulation of NiTi Temperature-sensitive Shape Memory Nanostructures

NiTi alloys are common shape memory alloys with good shape memory effect superelasticity corrosionresistance and biocompatibility. They have a wide range of applications in biomedical aerospace andmicroelectromechanical fields. Objective The wetting properties of different nanoscale structures on the surface of NiTi alloys were investigated to improve the wear and tear of NiTi alloys in the working environment and to increase the servicelife of NiTi alloys. Methods A molecular dynamics approach was used to simulate the shape memory effect of NiTi alloysunder periodic boundary conditions to study the microstructural evolution of NiTi alloy atoms at different temperatures.Meanwhile based on the different microstructures of NiTi alloys under the temperature response a droplet static contactangle simulation was built to investigate the wetting properties of NiTi alloy surface under different microstructures.Results NiTi alloys were found to undergo phase transformations in response to different temperatures resulting inchanges in the surface atomic arrangement of NiTi alloys. The temperature-induced phase transition and reverse phasetransition behaviors of NiTi alloys as well as the microstructural evolution at the atomic scale were demonstrated. Thesurfaces of NiTi alloys undergoing phase transition and reverse phase transition at different temperature responses were thenused as substrates and it was found that the wettability of their surfaces has also changed and recovered.Conclusion NiTi alloy undergoes phase transformation in response to temperature the microstructure changes and itssurface wettability also changes NiTi alloy undergoes reverse phase transformation in response to temperature themicrostructure is restored to the initial state and its surface wettability can be restored to the initial state accordingly. Theaustenite and martensite content of NiTi alloys during phase transformation affects the surface wettability of NiTi alloys.Therefore it is possible to adaptively regulate the wettability of NiTi alloy surfaces in the microstructure by temperature.