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Superhydrophobic Nanostructured Boehmite Coatings Prepared by AlN Powder Hydrolysis
Author(s) -
Kocjan Andraz,
Dakskobler Ales,
Kosmac Tomaz
Publication year - 2010
Publication title -
international journal of applied ceramic technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.4
H-Index - 57
eISSN - 1744-7402
pISSN - 1546-542X
DOI - 10.1111/j.1744-7402.2010.02516.x
Subject(s) - boehmite , materials science , contact angle , coating , nanoporous , crystallite , hydrolysis , surface energy , chemical engineering , composite material , substrate (aquarium) , superhydrophobic coating , metallurgy , nanotechnology , organic chemistry , aluminium , chemistry , oceanography , geology , engineering
A simple method that exploits the hydrolysis of AlN powder was used to deposit a nanostructured boehmite coating onto a polished sintered alumina substrate. The coating consists of interconnected polycrystalline nanoporous lamellas and exhibits a large specific surface area. Heat treatment of the as‐deposited coating at 500°C transformed it to γ‐alumina, and then to δ‐alumina at 900°C, with no substantial change in the morphology. However, the nanoporosity of the lamellas disappeared after the heat treatment at 900°C. After a subsequent chemical modification of the coatings with various low‐energy‐surface chemicals, that is, carboxylic acids, heptadecafluoro‐1,1,2,2‐tetrahydrodecyl trimethoxy‐silane (FAS), the initially highly hydrophilic coatings were transformed into a hydrophobic ones. Carboxylic acids proved to be less‐effective low‐energy‐surface chemicals because they produce hydrophobic surfaces with a water droplet contact angle of only 135°. A superhydrophobic surface, exhibiting a water‐droplet contact angle of 155°, was prepared by modifying the boehmite or γ‐alumina coating with FAS.