Self-healing behavior in high-deposition-rate sputtered Al·Al2O3 nanocomposite coatings for enhanced corrosion resistance

PVD coatings have limitations as corrosion-resistant coatings mainly because the rapid condensation resulting in insufficient atoms diffusion during the vapor deposition process leads to non-dense coating growth, preventing the coating from completely isolating corrosive agents. The mid-frequency Al target magnetron reactive sputtering method, by precisely controlling the O 2 flow rate, has produced a nanocomposite coating consisting of nano-Al and amorphous Al 2 O 3 . During the corrosion process, the nano-Al gradually oxidizes, filling the pinholes, thus providing a self-healing effect that completely isolates the corrosive agents. This results in the coating exhibiting significantly improved corrosion resistance, enhancing the corrosion resistance by 10 orders of magnitude compared to 304 stainless steels . • A composite coating of amorphous Al 2 O 3 and nano-Al was made via reactive magnetron sputtering with controlled oxygen flow. • Nano-Al reacts with corrosive agents to form Al 2 O 3 and Al 2 (SO 4 ) 3 , filling pinholes and enabling self-healing. • The composite PVD coating improves corrosion resistance 10 times over traditional PVD coatings and 304 stainless steels.