Superhydrophobic and Self-Healing Mg-Al Layered Double Hydroxide/Silane Composite Coatings on the Mg Alloy Surface with a Long-Term Anti-corrosion Lifetime

Abstract

Both a superhydrophobic structure and layered double hydroxide (LDH) coating were effective to improve the corrosion resistance of alloys. In this study, a superhydrophobic composite coating based on LDHs was constructed on Mg alloy by laser treatment, in situ growth of Mg-Al LDHs, and modification with octadecyl-trimethoxy-silane (OTS). The so-obtained composite coating was coded as L-LDHs-OTS, where L stands for laser treatment. Results showed that the L-LDHs-OTS composite coating presented the best anti-corrosion performance and the corrosion current density was reduced by about 5 orders of magnitude compared with that of the Mg alloy substrate. The excellent corrosion resistance was related to the superhydrophobicity of the composite coating, the compactness and ion-exchange capacity of the LDH layer, and the dense Si-O-Si network within the OTS layer. Moreover, the L-LDHs-OTS composite coating was still effective after 20 days of immersion tests, showing good long-term corrosion resistance due to the existence of hydrophobicity of the composite coating and the self-healing ability of LDHs.

The Potential of the Superhydrophobic State to Protect Magnesium Alloy against Corrosion

“…Despite the simple route of preparation of coatings reported here, their efficiency shows to be comparable with the best discussed in the literature coatings having complex structure and composition [12,13]. Since the reliability of the anticorrosion systems is critically dependent on their complexity, the coatings fabricated in this study look very attractive for practical applications.…”

“…As examples of these approaches, here we would like to mention the modification of the magnesium surface by sol-gel precoatings [5], anodization followed by different postanodization treatments [6], cold spray layers [7], various conversion coatings [5][6][7][8] including Mg-Al layered double hydroxide, hydroxide, and magnesium phosphate layers. Particular attention was paid to the application of the water-repelling coatings, such as superhydrophobic or slippery liquid-infused porous coatings, to protect the magnesium coatings against electrolytic and microbiologically induced corrosion [12][13][14][15][16][17][18][19][20][21][22][23][24].…”

Development of Multifunctional CoAl Based Layered Double Hydroxide Protective Film on Aluminum Alloy

“…When PFDTS was added to ethanol, a hydrolysis reaction of PFDTS occurred. Si-OH groups could be obtained due to the hydrolysis of the three Si-Cl groups of PFDTS [33]. Thus, it could induce hydrogen bond formation between Si-OH groups and -OH groups of LDH.…”

Progress in bioactive surface coatings on biodegradable Mg alloys: A critical review towards clinical translation

“…In recent years, organic coatings have received extensive attention for their superior corrosion resistance and multiple bio-functionalities [ 131 , 285 , 286 ]. Sol-gel is the highly reported coating technique for Mg and its alloys due to its capability to coat organic and inorganic materials on Mg alloys [ 287 ].…”