Superhydrophobic materials are hydrophobic materials with a hydrophobic angle of more than 150 °, so they have unique wetting properties, which can greatly reduce the adhesion of water droplets, and have important application value in the fields of self-cleaning, anti-icing, and drag reduction in water. However, the realization of super-hydrophobic properties mostly requires the modification of micro-nano structures and low surface energy organic materials, so their mechanical, high temperature resistance, and aging resistance are poor. Compared with organic materials, inorganic materials have better mechanical properties and durability, so the development of inorganic superhydrophobic materials has important research significance and application value.
Recently, the team of Pan Feng and Wu Zhongzhen of the School of New Materials, Peking University Shenzhen Graduate School successfully prepared a combination of heterogeneous alumina modified with negative surface energy θ-Al2O3 nanomaterials and nano / micron void structure to form a new inorganic superhydrophobic coating Composite materials, and then proposed to form a new generation of pure inorganic superhydrophobic material structure from the "positive + negative + zero" surface energy combination material.
In 2004, Norskov proposed that theta-Al2O3 phase has a negative surface energy at the solid / water interface ("A negative surface energy for alumina", Nature Materials, vol. 3, no. 5, pp. 289–293) through theoretical calculations. Based on the self-developed supercritical electrochemical technology of arc plasma and water-based electrolyte, the research team of the School of New Materials has achieved multi-phase on the surface of aluminum alloy by adjusting the multi-step continuous electrochemical reaction such as high temperature fast cooling and acid-base change. Preparation of alumina micro-nano structure coating, and through micro-etching to make θ-Al2O3 nanometers based on negative surface energy embedded in the low surface energy microstructure surface, so as to achieve the overall superhydrophobic performance. The research team conducted tests on high temperature resistance, aging resistance, wear resistance and corrosion resistance. The test results show that the coating can maintain super-hydrophobicity of more than 150 ° after being treated with open flame and high temperature heating at 300 ° C. Performance; after 360 days of exposure to sunlight, the hydrophobic angle has not decreased significantly; under 10 N load and non-woven fabric for 2000 times, it can still maintain a hydrophobic angle of more than 130 °; since the water drops do not wet on its surface, its resistance The corrosion performance is outstanding, especially the corrosion current reaches the order of 10-10 A / cm2.
This work is the first to realize the low surface energy embedded negative surface energy (θ-Al2O3) and zero surface energy air micro / nanopore structure to form a new generation of super-hydrophobic material structure, and realized its one-step continuous preparation. Its excellent mechanics, high temperature resistance, aging resistance and abrasion resistance will meet the complex and demanding application requirements in the engineering field, and show a broad application prospect in the aerospace, marine equipment and other fields.