A silanol-based nanocomposite coating for protection of AA-2024 aluminium alloy

Surface modification of ZrO2 nanoparticles with styrene coupling agent and its effect on the corrosion behaviour of epoxy coating

“…During the whole immersion experiment, the coating resistance decreased and the coating capacitance increased gradually, which were induced by water absorption during the initial immersion time, swelling of the coating, and ZrO 2 nanoparticles fi lling the pores of the coating tightly. Therefore, the coating inhibited the penetration of corrosive species, and the coating resistance increased again to a stable state (Andreatta et al, 2007;Gonzalez et al, 2011).…”

Development and performance of hybrid coatings on aluminium alloy

“…In their findings, the coating is generally about 50-70nm in thickness and it was said to be essentially of MnO2 in its outermost regions with a composite of Al-Mn oxides predominantly at the metal/coating interphase. As the search for alternatives to chromates proceeds far and wide, other researchers are looking into sol-gel formulations such as aluminum-based sol-gel materials by Oubaha et al [9], and silanol-based nanocomposite by Gonzalez et al [10] with much success recorded in terms of improved paint adhesion characteristics which compared favorably with the chromates. Nonetheless, some of these formulations and processes have been patented [11] but their applications have been limited to the lower technical end of the metal finishing markets while in the high technical end as in the aerospace industry as well as military hardware, chromates are still preferentially employed [12].…”

Routes to extrinsic and intrinsic self-healing corrosion protective sol-gel coatings: a review

“…As reported by Palanivel et al, the addition of silica particles with average diameter of 1 µm to BTESPT films, in the range of 5-15 ppm, increased corrosion protection properties of these films, as a small amount of silica can react with cathodically generated OH − ions, and form a passive Al-silicate compound on cathodic areas of AA2024 surface [74]. Nevertheless, agglomeration of the embedded particles, which can be facilitated by gelation process, may lead to coating rupture and deterioration of the coating barrier properties [75]. Further reduction in corrosion resistance of bis-[trimethoxysilylpropyl]amine (BTSPA) coated carbon steel has been reported for silica particles volume concentration (PVC) > 300 ppm due to agglomeration of the embedded silica particles [76].…”