镍钛合金表面微纳结构构建及其疏水性能研究

Study on Construction of Micro-nano Structure and Hydrophobicity of Ni-Ti Alloy Surface

基于相对自由能和润湿方程,从平行沟槽方向和垂直沟槽方向探究镍钛合金表面单向沟槽阵列结构的润湿机制,建立Wenzel态和Cassie-Baxter态下的液滴接触角模型,分析不同尺寸参数下的接触角理论值。通过微铣削加工技术对镍钛合金表面进行改性处理,加工出所需的微结构,并采用VHX-5000超景深三维显微镜和JC2000D1型接触角测量仪测量分析其表面形貌、尺寸参数以及实际接触角。结果表明:微铣削制备的镍钛合金表面阵列结构尺寸精度较好,结构边界完整,满足设计要求;平行方向的实际接触角随着柱宽的增大而减小,最大静态接触角为145.4°,与平行方向的Cassie-Baxter态接触角趋势相符;垂直方向的Cassie-Baxter态理论接触角在数值上等于镍钛合金表面的本征接触角;同时垂直方向的实际接触角与Wenzel态接触角趋势不符,误差在42.1°内。

Based on the relative free energy and Young's equation,the wetting mechanism of the unidirectional groove array struc⁃ture on the surface of Ni-Ti alloy was explored from the parallel groove direction and the vertical groove direction.The contact angle models under Wenzel state and Cassie-Baxter state were established,and the theoretical values of contact angle under different size pa⁃rameters were analyzed.The surface of Ni-Ti alloy was modified by micro-milling technology to process the required microstructure.The surface morphology,size parameters and actual contact angle were measured and analyzed by the VHX⁃5000 super depth 3D microscope and JC2000D1 contact angle measuring instrument.The results show that the Ni-Ti alloy surface array structure prepared by micromilling has good dimensional accuracy and complete structural boundary,which meets the design requirements;the actual contact angle in parallel direction decreases with the increase of column width,and the maximum static contact angle is 145.4°,which is consistent with the trend of Cassie-Baxter contact angle in parallel direction;the theoretical contact angle of the Cassie-Baxter state in the vertical direction is numerically equal to the intrinsic contact angle of the Ni-Ti alloy surface;at the same time,the actual contact angle in the vertical direction is inconsistent with the Wenzel state contact angle,and the error is within 42.1°.