Electrostatic powder spraying process for the fabrication of stable superhydrophobic surfaces

Nano-sized Al(2)O(3) particles were modified by heptadecafluorodecyl trimethoxysilane and 2,3-epoxy propoxy propyl trimethoxysilicane to make it both hydrophobic and reactive. The reactive nano-particles were mixed with polyester resin containing curing agents and electrostatic sprayed on stainless steel substrates to obtain stable superhydrophobic coatings after curing. The water contact angle (WCA) on the hybrid coating is influenced by the content of Al(2)O(3) particles in the coating. As the Al(2)O(3) concentration in the coating was increased from 0% to 8%, WCA increased from 68 degrees to 165 degrees. Surface topography of the coatings was examined using scanning electron microscopy (SEM). Nano-particles covered on the coating surface formed continuous film with greatly enhanced roughness, which was found to be responsible for the superhydrophobicity. The method is simple and cost effective and can be used for preparing self-cleaning superhydrophobic coating on large areas. (C) 2010 Elsevier B.V. All rights reserved.