Zhiqing Yuan

Fabrication of a superhydrophobic surface on copper foil based on ammonium bicarbonate and paraffin wax coating

A simple and low cost approach was developed to fabricate a superhydrophobic surface on copper foil. The oxidation and etching of the copper foil surface were promoted in NH4HCO3 solution using a water and ethanol admixture as a component solvent. After 28 h in this solution, a hydrophilic rough surface structure was obtained on the copper foil surface. With modification using a paraffin wax coating, the hydrophilic rough copper surface changed to become hydrophobic or superhydrophobic. The surface morphology and wettability were characterized by scanning electron microscopy (SEM) and contact angle measurements, respectively. When the optimum concentration of paraffin wax was about 2 g L−1, its water contact angle could reach about 152 ± 1.5° and its sliding angle was around 7°. The formation mechanism of the rough copper surface was also explored in detail. Both the experimental process and the material are environmentally friendly.

Construction of super-hydrophobic iron with a hierarchical surface structure

Wettability of an iron surface is crucial for the wide applications of iron in practice. In this work, a hierarchical structure highly similar to that of the underside of a bamboo leaf was constructed on an iron surface via the template method and controllable etching. After modification by stearic acid, the iron surface with hierarchical structure showed excellent water repellency, with an average contact angle of 156° and a sliding angle of 3°. X-ray diffraction (XRD) techniques and Fourier transform infrared spectroscopy (FTIR) are applied to examine the chemical components of an iron surface.

Icephobicity and the effect of water condensation on the superhydrophobic low-density polyethylene surface

A superhydrophobic surface was obtained on a low-density polyethylene (LDPE) substrate using a facile method. The water contact angle and the sliding angle of the superhydrophobic LDPE surface were 155 ± 2° and 4°, respectively. The ice shear stress of the superhydrophobic LDPE surface was 2.08 times smaller than that of the flat LDPE surface. The superhydrophobic surface still showed excellent icephobicity and superhydrophobicity after undergoing a circulatory icing/deicing procedure five times. In addition, water condensation and its effect on the icephobicity of the as-prepared superhydrophobic surface were also studied.

A facile method of fabricating mechanical durable anti-icing coatings based on CeO2 microparticles

Compromising between hydrophobicity and mechanical durability may be a feasible approach to fabricating usable anti-icing coatings. This work improves the contact angle of current commercial anti-icing coatings applied to wind turbine blades dramatically and keeps relatively high mechanical durability. CeO2 microparticles and diluent were mixed with fluorocarbon resin to fabricate high hydrophobic coatings on the glass fiber reinforced epoxy composite substrates. The proportion of CeO2 microparticles and diluent influences the contact angles significantly. The optimum mass ratio of fluorocarbon resin to CeO2 microparticles to diluent is 1:1.5:1, which leads to the highest contact angle close to 140°. The microscopy analysis shows that the CeO2 microparticles form nano/microscale hierarchical structure on the surface of the coatings.

Study on the adherence and superhydrophobicity of polypropylene composite coating on aluminum alloy substrate

A composite superhydrophobic coating was tape casted on the surface of aluminum alloy specimens which is composed of maleic anhydride grafted polypropylene (PP-g-MAH) and polypropylene (PP). The aluminum alloy specimens were pretreated by silane coupling agent KH550 to increase the adherence between aluminum alloy specimens and PP-g-MAH. The pretreatment surfaces were characterized by the Fourier transform infrared spectroscopy (FTIR). The adherence and superhydrophobicity of the composite coating were also tested by QFZ-II adhero meter and OCA-20 optical contact angle meter, respectively. Finally, the morphology of the composite coating was also investigated by Scanning Electron Microscopy (SEM). The results indicate that KH550 is mainly responsible for the increase of adherence between aluminum alloy specimens and PP-g-MAH due to the formation of chemical bond Si-O-Al and polysiloxane coating. As for the superhydrophobicity, the PP coating covers the polar group maleic anhydride which restricts the decrease of superhydrophobicity. At the same time, the concentration of PP-g-MAH and PP solution has an important effect on the hierarchical structure and superhydrophobicity of the composite coating. When the concentration is 5 g L−1, the coating has a fine structure with an unsatisfying hydrophobicity. When the concentration is more than 17 g L−1, the composite coating has a prominent hierarchical structure and its superhydrophobicity keeps at relative stable level. However, when the concentration is more than 50 g L−1, the solution has a weak spreadability and the coating can not easily flow flatly. Sometimes the coating will be cracked.