posted on 2024-02-09, 22:10authored byZhaochang Wang, Xiaojun Liu, Yuhang Guo, Baohong Tong, Guotao Zhang, Kun Liu, Yunlong Jiao
Superhydrophobic surfaces (SHSs)
have possibilities for
achieving
significantly reduced solid–liquid frictional drag in the marine
sector due to their excellent water-repelling properties. Although
the stability of SHSs plays a key role in drag reduction, little consideration
was given to the effect of extreme environments on the ability of
SHSs to achieve drag reduction underwater, particularly when subjected
to acidic conditions. Here, we propose interconnected microstructures
to protect superhydrophobic coatings with the aim of enhancing the
stability of SHSs in extreme environments. The stability of armored
SHSs (ASHSs) was demonstrated by the contact angle and bounce time
of droplets on superhydrophobic surfaces treated by various methods,
resulting in an ASHS surface with excellent stability under extreme
environmental conditions. Additionally, inspired by microstructures
protecting superhydrophobic nanomaterials from frictional wear, the
armored superhydrophobic spheres (ASSPs) were designed to explain
from theoretical and experimental perspectives why ASSPs can achieve
sustainable drag reduction and demonstrate that the ASSPs can achieve
drag reduction of over 90.4% at a Reynolds number of 6.25 × 104 by conducting water entry experiments on spheres treated
in various solutions. These studies promote a fundamental understanding
of what drives the application of SHSs under extreme environmental
conditions and provide practical strategies to maximize frictional
drag reduction.