Abstract
In this study, a series of MgAl–layered double hydroxide (LDH) thin films were synthesized by a single step hydrothermal process at different synthetic conditions on AA6082, and the combined effect of reaction temperatures and crystallization times on in situ growth MgAl–LDH structural geometry, growth rate, and more importantly on the corresponding corrosive resistance properties are briefly discussed. The synthesis of LDH was performed at reaction temperatures of 40, 60, 80, and 100 °C, while the treatment time was varied at 12, 18, and 24 h. The as-prepared synthetic coatings were characterized by scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR), while the corresponding corrosion protection efficiency of the developed coating was studied through potentiodynamic polarization studies and electrochemical impedance spectra. The findings demonstrated that extended crystallization time and reaction temperature impart a significant effect on the oriented growth of layered double hydroxide, the surface morphology, and on the film thickness, which had a remarkable influence on the LDH corrosion resistance ability. The LDH coated specimen developed at 100 °C for 18 h reaction time showed a more compact and dense structure compared to the traditional platelet structure obtained at 80 °C for 24 h crystallization time, and interestingly that compact structure exhibited the lowest corrosion current density, up to five orders of magnitude lower than that of bare AA6082.
Highlights
Aluminum and its alloys are considered promising materials for a number of applications due to their high strength to weight ratio and relatively high thermal and electrical conductivities, along with their abundance and low price
Be seenItthat temperature sharpness of the peaks an ordered structure of It can synthesis be seen that synthesis and crystallization time have antime influential effect on characteristic peaks
The finding demonstrated that the reaction temperature and crystallization times have an influential effect on the growth mechanism of layered double hydroxide which has a strong impact on its corrosion resistance behavior
Summary
Aluminum and its alloys are considered promising materials for a number of applications due to their high strength to weight ratio and relatively high thermal and electrical conductivities, along with their abundance and low price. In this work we succeeded to synthesize a series of MgAl–NO3 LDH film on the surface of AA6082 by using magnesium salt only, and developed a range of balanced combinations of reaction temperature and aging time, at constant initial cationic concentration (Mg2+ ) to investigate in detail the impact of the above-mentioned parameters on LDH geometry, structural growth, morphology, and their effect on the corresponding corrosion resistance properties. In this study, the one-step in situ growth method was used to develop MgAl–LDH coatings on AA6082 at different combinations of extended reaction temperature and crystallization time without using any surfactants or complexation reagents This was done in order to understand the effect of the mentioned parameters on the geometry of LDH crystallites, film growth, and on the deposition rate to explain the relationship of LDH structural variations with its anticorrosion behavior. This work provides insight into the corrosion resistance properties of MgAl–LDH, and into the correlation between the electrochemical response of the coatings and their structural properties
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