In Situ Growth of High-Performance ZnAl-Layered Double Hydroxides/Al2O3 Composite Coatings on Aluminum Alloy

In this research, high-performance ZnAl-layered double hydroxides (ZnAl-LDHs) with different Zn2+ concentrations were prepared on the surface of an anodized 1060 aluminum alloy using the in situ growth method, and the influence of Zn2+ concentration on corrosion resistance and tribological behavior was further explored. The surface morphology, element distribution, phase composition, and mechanical performance of ZnAl-LDHs/anodic aluminum oxide (AAO) composite coatings were tested and analyzed. Subsequently, the investigation of the anti-corrosion properties and tribological behavior of as-prepared composite coatings and AAO were conducted experimentally. The results show that with the increase in Zn2+ concentration, the thickness and bonding strength of the coatings gradually increase, and the hardness progressively decreases. The ZnAl-LDHs/AAO composite coating with a Zn2+ concentration of 0.3 mol/L exhibits the best anti-corrosion ability, which has the minimum corrosion current density of 2.435 x 10(-9) A/cm(2). This can be attributed to the uniform and compact ZnAl-LDH films where the porous structure of the AAO is well sealed. Moreover, the excellent friction-reduction and anti-wear properties of ZnAl-LDHs/AAO composite coatings with larger Zn2+ concentrations are verified using a ball-on-disc rotating wear tester under dry wear. A reasonable mechanism for improving tribological properties of resulting ZnAl-LDHs/AAO composite coatings is proposed.

Automated summary

In this research, high-performance ZnAl-layered double hydroxides (ZnAl-LDHs) with different Zn2+ concentrations were prepared on the surface of an anodized 1060 aluminum alloy. The influence of Zn2+ concentration on corrosion resistance and tribological behavior was explored. The results showed that with the increase in Zn2+ concentration, the thickness and bonding strength of the coatings increased, while the hardness decreased. The ZnAl-LDHs/AAO composite coating with a Zn2+ concentration of 0.3 mol/L exhibited the best anti-corrosion ability and excellent friction-reduction and anti-wear properties.