One-step dipping method to prepare inorganic-organic composite superhydrophobic coating for durable protection of magnesium alloys

It is a great challenge to fabricate the superhydrophobic coating with durable protection ability in one-step facile way. Here we develop a simple and scalable one-step dipping method to prepare the superhydrophobic coating of aluminum phosphate (AP) and polytetrafluoroethylene (PTFE) for durable protection of magnesium alloys. The coating was characterized by using contact angle meter, high-speed camera, field emission scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The anti-corrosion performance and comprehensive durability of the coating were evaluated by the electrochemical methods and various mechanical/physical and chemical durability tests, respectively. The as-prepared AP-PTFE inorganic-organic composite coating is composed of compactly arranged ellipsoidal nanospheres. The coating is superhydrophobic with a water contact angle of 155.7°, which demonstrates high resistance to corrosive medium and extraordinary durability to resist various mechanical/physical and chemical damage. The enhanced interaction force between the coating and the substrate that was derived from the reaction between the inorganic binder AP and the active Mg alloy, the corrosion inhibition of polymerized AP, and the high corrosion resistance of PTFE are responsible for the coating extraordinary durability. This study provides a promising strategy for large-scale production of durable superhydrophobic coatings.