超疏水结构对AZ91D镁合金微摩擦磨损性能的影响

目的 研究微/纳米复合超疏水结构的摩擦磨损机制，提高镁合金微摩擦磨损性能。方法 首先采用激光刻蚀获得微米结构，然后表面涂覆SiO2纳米颗粒，获得微/纳米复合结构，最后涂覆低表面能物质获得超疏水表面。用接触角测量仪测量超疏水表面的静态接触角，使用微摩擦磨损实验机分析超疏水表面的摩擦磨损性能，使用扫描电子显微镜观察表面磨痕形貌。结果 当载荷为1 N时，超疏水表面的摩擦系数约为0.04，基体表面约为0.06。随着载荷的增加，超疏水表面的摩擦系数逐渐与基体相近，并逐渐超过基体。随着时间的增加，超疏水表面的摩擦系数呈增加趋势，由0.04逐渐增加到0.08，基体试样没有明显的上升趋势。相同条件下，超疏水表面的磨痕宽度大于基体表面，但磨痕宽度的增大趋势小于基体表面。结论 微/纳米复合结构超疏水表面的摩擦磨损过程不同于光滑基体。超疏水表面的磨损首先发生于微/纳米凸起结构，之后发生于被微/纳米凸起填平的微米凹坑区，然后发生于激光加工热影响区表面，最后发生于镁合金基体。在所受载荷低于1~3 N时，超疏水表面微凸起结构能延缓超疏水表面摩擦磨损的发生，改善耐磨性能。

Effect of Superhydrophobic Structure on Microfriction and Wear Properties of AZ91D Magnesium Alloy

The work aims to study the friction and wear mechanism of micro/nano composite superhydrophobic structures to improve the micro-friction and wear performance of magnesium alloys. Firstly, the micron structure was obtained by laser etching, then the surface was coated with SiO2 nanoparticles to obtain the micro/nano composite structure, and finally the superhydrophobic surface was obtained by coating the low-energy surface materials. The static contact angles of superhydrophobic surface were measured by the contact angle meter, the friction and wear performance was analyzed by micro-friction and wear tester and the microstructures of surfaces were examined by SEM. When the load was 1 N, the friction coefficient of the superhydrophobic surface was about 0.04, and that on the surface of the matrix was about 0.06. As the load increased, the friction coefficient of the superhydrophobic surface was close to that on the matrix and gradually exceeded that on the matrix. With the increase of time, the friction coefficient of the superhydrophobic surface increased from 0.04 to 0.08. However, there was no obvious rising trend of matrix samples. In the same conditions, the wear scar width of the superhydrophobic surface was greater than that of the matrix surface, but the increasing trend of the wear scar width was smaller than that of the matrix surface. The friction and wear process of micro/nano composite superhydrophobic surface is different from that of smooth matrix. The wear on the superhydrophobic surface first occurs on the micro/nano composite structure. After that, it appears in the micron pit area filled by the micro-nano/nanometer bump, then on the surface of the heat-affected zone of laser processing, and finally on the magnesium alloy matrix. When the load is lower than 1~3 N, the microconvex structure on the superhydrophobic surface can delay the occurrence of friction and improve the wear resistance.