Liu Weilan,Li Kunlong,Shen Yizhou,Zhao Huanyu,Ni Yaru,Cai Zeyu,Zhao Lingfeng,Wang Zhen
Superhydrophobic coatings with high non-wetting properties are widely applied in anti-icing applications. However, the micro-nanostructures on the surfaces of superhydrophobic coatings are fragile under external forces, resulting in reduced durability. Therefore, mechanical strength and durability play a crucial role in the utilization of superhydrophobic materials. In this study, we employed a two-step spraying method to fabricate superhydrophobic FEVE-based coatings with exceptional mechanical durability, utilizing fluorinated TiO 2 nanoparticles and fluorinated Al 2 O 3 microwhiskers as the fillers. The composite coating exhibited commendable non-wetting properties, displaying a contact angle of 164.84° and a sliding angle of 4.3°. On this basis, the stability of coatings was significantly improved due to the interlocking effect of Al 2 O 3 whiskers. After 500 tape peeling cycles, 500 sandpaper abrasion tests, and 50 kg falling sand impact tests, the coatings retained superhydrophobicity, exhibiting excellent durability and application capability. Notably, the ice adhesion strength on the coatings was measured at only 65.4 kPa, while the icing delay time reached 271.8 s at -15 °C. In addition, throughout 500 freezing/melting cycles, statistical analysis revealed that the superhydrophobic coatings exhibited a freezing initiation temperature as low as -17.25 °C.
Xiaoyao Qu,Fucheng Wang,Chunsheng Shi,Naiqin Zhao,Enzuo Liu,Chunnian He,Fang He
An aluminium matrix composite reinforced by in situ-generated gamma-Al 2 O 3 whiskers was fabricated from a simple Al-H 3 BO 3 system through cold pressing and sintering. The gamma-Al 2 O 3 whiskers with an average diameter of 20 nm and an aspect ratio of 10–15 were synthesized during the sintering process and homogeneously distributed in the Al matrix. As a result of the perfect lattice matching between gamma-Al 2 O 3 and the Al matrix, the gamma-Al 2 O 3 whisker is a desired reinforcement for the Al matrix, improving the ultimate tensile strength and hardness to 217 MPa and 43.5 HV, respectively, with a satisfactory ductility of 11%. Differential scanning calorimetry analysis shows that the growth of the whisker occurred at 550–650 °C, and the ball milling energy has a significant effect on whisker growth.
Gang Huang,Chengzhe Gao,Jin Leng,Yang Wu,Liying Chen,Ran Jing,Pengshu Xie,Hua Deng,Qiwu Shi
As the communication band gradually approaches the terahertz (THz) range, there is an urgent need to explore materials with ideal dielectric properties for THz communication devices. Nevertheless, most polymers present a low dielectric constant (Dk), and the regulation of their dielectric properties in the THz range has rarely been reported. In this work, the isotactic polypropylene (iPP)/α-Al2O3whisker composites were synthesized and their THz dielectric parameters were optimized. TheDkvalues increased from 2.23 to 3.13 with filler (α-Al2O3whisker) concentration, ranging from 0 to 20 vol%, but were almost independent of the test frequency. The loss tangent (Df) values presented an increasing tendency along with both filler concentrations and test frequency. All composites exhibitedDfvalues of less than 4.0 × 10−3. Particularly, the dielectric properties of composites can be further regulated by adjusting the orientation direction of the whisker fillers. The orientation of the whisker fillers was adjusted via the injection molding method. Along the direction of the whisker orientation distribution, the composites exhibit higherDkvalues and lowerDfvalues. This work presented a schematic to design polymer composites with higherDkbut controlledDfin the THz range and is significant for the development of advanced materials-based THz devices.
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