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Gamma-irradiated silica sol-gel coatings as a function of dose on AA2024-T3

Abstract:

The present paper reports the behavior of gamma-irradiated hybrid sol-gel coatings based on the copolymerization of 3-glycydoxypropyltrimethoxysilane and tetra-n-propoxyzirconium applied onto aluminum alloy AA2024-T3. Doses from 1 to 100 kGy were applied on undoped sol-gel coatings and coatings doped with hydrotalcite at 1% and 5%, w/w. The sol-gel coatings were deposited by using the dip-coating method on an aluminum substrate with a final grinding of a 240-grit. Scanning electron microscopy revealed that the hydrotalcite particles were heterogeneously dispersed at several micrometers in length. High irradiation doses on doped hydrotalcite coatings showed no improvement in the corrosion resistance of the films at longer immersion times in saline media obtained by electrochemical impedance spectroscopy. Differential scanning calorimetry showed that the gamma-irradiated doses and the hydrotalcite content modify the thermal properties of the sol-gel coatings. X-ray diffraction results revealed modification of the hydrotalcite crystallite size as a function of irradiation dose.