This paper reports a simple approach for the preparation of superhydrophobic and oleophobic surface on zinc substrate. The surface was created by chemical etching and hydrothermal reaction, consisting of micro hexagonal prisms with about 4 μm in length, 0–1 μm in gap and 0.1–0.4 μm in diameter. The surface then became superhydrophobic and oleophobic with a fluoride coating, fabricated by chemically modified with perfluorooctanoic acid anhydrous ethanol solution. The effects of different process parameters, including chemical etching time and the hydrothermal temperature, on the surface morphology and wettability were examined using a scanning electron microscope (SEM) and a contact angle tester. The optimization of process parameters were obtained, namely, the chemical etching time was 90 s and the hydrothermal temperature was 95 °C. After zinc surface was treated using the optimum parameters, the results showed that the surface exhibited repellency toward distilled water and edible peanut oil with contact angles at 151.85° and 145.62°, respectively, and the sliding angle for distilled water was less than 10°.
Jie Li,Yue Yin,Lingjing Meng,Hui Qiao,Huan Zhang,Yunfei Cai,Yonglong Zhang,Feiyan Yang,Jinfang Wu,Mei Wu,Jian Liu,Wenbo Wang
Porous attapulgite (ATP) was employed as green container for storing corrosion inhibitors that can enhance both the corrosion inhibition and self-healing properties of organic coatings. The key to realizing ATP containers in smart corrosion resistance is clarifying the influence of ATP's surface charge on inhibitor loading capacity and the degradation behavior of ATP in active corrosion protection, but this aspect is often overlooked. Herein, an effective enhance the physical barrier and active corrosion resistance of the polyvinyl butyne vinyl acetate (PVB) coating by developing ATP containers was proposed. The results indicated that with the incorporation of 0.5 wt% Acid-etched ATP or BTA@ATP, the |Z| 0.01Hz of composite coatings on zinc substrate enhance six times (4.8 × 10 4 Ω cm 2 ) and sixteen times (1.2 × 10 5 Ω cm 2 ) than the pure PVB coating (7.8 × 10 3 Ω cm 2 ), respectively. The corrosion protection mechanism contributes to the filling of cracks with ATP nanocontainers to provide barrier protection, the release of corrosion inhibitors to passivate the damaged areas, as well as the degradation of the ATP itself to form a silicate layer to inhibit the progression of corrosion. Hence, the strategy of ATP nanocontainer preparation will facilitate the high-value utilization of attapulgite and potentially provide guidance for researchers in designing micro/nano-containers.
A silicate and phosphate composite passive film on zinc was prepared from a composite passivation solution containing zinc dihydrogen phosphate and sodium metasilicate. The morphology, composition, valence and functional groups of the passive film with different passivation times were analyzed through field-emission scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy, X-ray photoelectron spectroscopy and infrared spectroscopy to understand its evolution process. The passive film exhibits a cyclic film-forming process with a periodic ratio of silicate and phosphate, which is caused by the periodic changes in the alkalization degree of the interface between the electrode and the solution. Such periodic film-forming process promotes the passive film growth and makes the passive film uniform and dense. Electrochemical analysis, immersion tests and copper sulfate spotting tests illuminate that the composite passive film is more corrosion-resistant than the pure silicate passive film. This composite passivation film exhibits a uniform corrosion behavior with gradually expanding micropores due to the effective inhibition of inward diffusion and permeation of chloride ions by the dense film structure of cyclic growth, which avoids the pinhole corrosion and improves the protection of the passivation film.
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