In-situ growth and mechanism of MgAl-NO3-LDHs film on Ti6Al4V via one-step hydrothermal treatment with a high concentration of alkaline growth solution

作者：Zhou, Bingtao; Wei, Wei; Gao, Yan^*

来源：Surface and Coatings Technology, 2023, 475: 130146.

DOI：10.1016/j.surfcoat.2023.130146

• Titanium alloy
• LDHs
• In-situ growth
• Alkaline concentration
• Mechanism

The stable TiO2 passive film on titanium alloys has made it very difficult the in-situ growth of layered double hydroxides (LDHs) on their surface. In this paper, the in-situ growth of MgAl-NO3-LDHs on TC4 titanium alloy (Ti6Al4V) was successfully realized by one-step hydrothermal treatment with a high concentration of alkaline growth solution. The in-situ growth process of MgAl-NO3-LDHs on Ti6Al4V under different concentrations of growth solution was investigated by characterizing the morphology, structure and composition of the LDHs at different growth time. It was found that the key to the in-situ growth of MgAl-NO3-LDHs on Ti6Al4V was the conversion of the surface TiO2 and Al2O3 passive film to Ti(OH)2 6 and Al(OH)4 which acted as active sites for the immobilization of LDHs crystal nuclei on Ti6Al4V, under a much higher concentration of alkaline growth so-lution than that for the low corrosion resistant alloys. The conversion degree of TiO2 and Al2O3 passive film to active sites increased with increasing growth solution concentration, and thereby increased the MgAl-NO3-LDHs content and reduced their lamellas size. The growth process of MgAl-NO3-LDHs on Ti6Al4V is composed of three stages: active sites formation, dense growth and sparse growth of the LDHs.

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