Hierarchical alveolate structures in nano- to microscale were fabricated on both aluminum and stainless steel substrates via a chemical etching. On aluminum surfaces, sharp edged caves and plateaus were found. On stainless steel substrate, fine papillae stand on protuberances. These surfaces exhibit super-hydrophobic properties after the fluorination treatment, their water contact angles are 158° and 160°, respectively, with the contact angle hysteresis of about 5°. The roll off angle is about 5°. Ice melting behaviors on a plate of aluminum super-hydrophobic surface were compared with those on a hydrophilic one, their difference shows that the new feature of super-hydrophobic surface could be expected.

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Polytetrafluoroethylene-polyphenylene sulfide composite coating mesh film was successfully prepared by a simple layered transitional spray-plasticizing method on a stainless steel mesh. It shows super-hydrophobic and super-oleophilic properties. The contact angle of this mesh film is 156.3°for water, and close to 0°for diesel oil and kerosene. The contact angle hysteresis of water on the mesh film is 4.3°. The adhesive force between the film and substrate is grade 0, the flexibility is 1 mm and the pencil hardness is 4H. An oil-water separation test was carried out for oil-contaminated water in a six-stage superhydrophobic film separator. The oil removal rate can reach about 99%.

Superhydrophobic boehmite film has been successfully prepared on a glass substrate by a sol-gel method. A chelated Aluminum-sec-butoxide (Al(OBu s ) 3 ) solution, instead of aluminum hydroxide collosol, was used for the film coating. By immersing the film in boiling water, boehmite crystal was formed on a glass substrate. Subsequently, the rough surface was modified with fluoroalkylsilane (FAS). The result shows that the water droplet contact angle on the surface is 168.3°. The superwater-repellency is caused by the micro-nano structure and the low surface energy of the fluorinated surface. The reaction mechanism is proposed with the help of SEM, XRD and FT-IR analysis.

Reducing the flexspline (FS) deformation is important for decreasing the alternating stress, flare angle in the axial direction, spatial deformation of teeth, and tube length. However, it may increase the probability of insufficient engagement depth and nonexistent conjugate tooth profiles. In this study, a mathematical model of the harmonic drive (HD) with a new tooth profile is proposed to reduce the FS deformation while satisfying the engagement depth and existence of a conjugated tooth profile. First, the generation mechanism of the new tooth profile is discussed in detail and the connection method of the circular arc tooth profile and transition tooth profile in the FS were presented. Then, two key parameters of the model, the translation distance and offset distance were studied to design the ideal tooth profile. Finally, a tooth root chamfer method was proposed to achieve smooth operation of the HD. Additionally, owing to the lack of a wear assessment of the new tooth profile, a sliding coefficient calculation model was presented. To verify the feasibility of the models, a prototype with a radial deformation coefficient of 0.8 was designed, processed, and tested. The experimental results were consistent with the theoretical analyzes.