In situ fabricated yttrium doping coatings on aluminum alloy as highly affinity kosmotrope fluorine anti-corrosion surface

Abstract

Aluminum (Al) alloys have been widely used in semiconductor equipment due to their excellent high specific strength and machinable property. However, the strong electronegativity and high surface charge density in the fluorine environment of process manufacturing tend to result in its poor corrosion resistance performance. Addressing the brittle behavior of fluorides due to strong ionic bonding and the corrosion attack mechanism triggered by the special electronic structure properties of fluoride ions remains a challenge. Studies have indicated that rare earth yttrium (Y) can enhance the fluorine corrosion resistance of ceramic coatings by modifying the fluoride passivation layer structure. In this work, we demonstrate a new strategy for developing high-quality yttrium assisted fluorine corrosion resistant novel coating in situ on aluminum alloy (6061) by two-step micro-arc oxidation (MAO) process. The coatings maintain sustainable corrosion protection and excellent wear resistance performance after 28 days immersion in 0.1 mol/L NaF solution. The results show that the loading of yttrium leads to effectively mitigating the fatal microcracks on the surface by inhibiting the growth of oxygen vacancies in the coatings, and promotes the formation of small sized structures. The stronger and more robust Al-O covalent network structure provides better physical barrier effect and reduces the strong penetration intrusion of small radius fluoride ions. Density-functional theory (DFT) calculations show that matching affinity kosmotrope fluoride ions on the atomic level significantly reduce the adsorption effect on the coating surface. Moreover, yttrium can improve the interfacial dislocation effect of low fracture toughness fluoride reaction film, and effectively inhibit the crack extension of corrosion products as well as promote the stability of corrosion interfacial interaction.