Multi-Dimensional Design of Slippery Liquid-Infused Coatings Empowering Long-Term Corrosion Protection for Sintered Nd-Fe-B Magnets in Harsh Environments

Abstract

In spite of superior magnetic properties, neodymium–iron–boron (Nd-Fe-B) applications in harsh environments have been greatly hindered by their susceptibility to corrosion, humidity, mechanical, and temperature attacks. Herein, a construction strategy of robust slippery liquid-infused porous surfaces (SLIPS) coatings is proposed via the multi-dimensional design of surface, bulk coating, and interface. The manipulation of colloidal states of silica particles by chemical hydrophobization allows for building a dense polymer network, enhancing interfacial adhesion and locking lubricant film effectively. The resulting coating is demonstrated to be extremely stable, endowing the magnet with excellent liquid repellency, anti-corrosion, and anti-icing properties. Strikingly, no trace of corrosion is detected after 136-day immersion in 3.5 wt.% NaCl solution and the impedance modulus at 0.1 Hz can be maintained as the initial of 3.31 × 10⁸ Ω·cm² even after 132-day immersion, which is far superior to that of commercial Ni-Cu-Ni, Zn, and EP coatings. Additionally, anti-icing performance at low temperatures is evidenced by the delayed icing time and decreased ice adhesion strength. Importantly, the self-healing property offers the surface intensified durability even after mechanical damage. This work demonstrates a construction strategy of robust SLIPS coatings with a multi-dimensional design, enabling the practical applications of Nd-Fe-B magnets in extreme environments like offshore wind turbines.