Steels are widely used not only in daily life but also in urban infrastructure and industry owing to their good ductility, thermal and electrical conductivity, weldability, and malleability. However, the corrosion of steels by chemical reactions under aggressive environments such as humid marine atmosphere, saline seawater, and acidic/alkaline electrolytes results in massive annual losses worldwide.
In a new paper published in Light: Science & Applications , Professor Huailiang Xu from Jilin University of China and co-workers developed a strong-field laser passivation strategy to obtain super corrosion-resistant stainless steels through forming a hybrid µm-Fe 3 O 4 /Fe 2 O 3 /Cr 2 O 3 passivation layer with unique bionic taro-leaf-like hierarchically heterogeneous Cassie-state micro/nanostructure morphologies. They fabricated stainless steels by a strong-field laser filament (SLF), which provides a constant laser field intensity as high as 50−100 (TW·cm -2 ), and can be straightforwardly extended to the large-scale processing of rough and irregular stainless-steel surfaces at a standoff distance. They also demonstrated that the ultralow corrosion rate of stainless steels can remain for >6500 hours. In particular, the generality of the proposed technique was exemplified by exhibiting extreme anticorrosion enhancements of AISI 316, 420, 201, 430 and 2205 steels under the same conditions.
These scientists summarize the operational principle of their SLF technique: “the SLF processing promotes not only the formation of a passive hybrid Fe 3 O 4 /Fe 2 O 3 and Cr 2 O 3 layer having abundant Cr content, which reinforces the surface oxidation resistance, but also the formation of unique bionic taro-leaf-like hierarchically heterogeneous Cassie-state micro/nanostructures having deep ravines and flat mountaintops. Indeed, the micro/nanostructures greatly suppress pitting corrosion and build up a physical barrier through ultra-hydrophobicity to inhibit an exposure of the metal surfaces to corrosive solutions.”
“With recent advances in high-repetition-rate high-energy femtosecond lasers, it is anticipated that the SLF fabrication can be operated with much higher efficiency on a variety of irregularly shaped surfaces by designing the filamentation to occur over a far distance in the atmosphere for practical applications in industry.” the scientists forecast.
Light Science & Applications
Significant reduction of corrosion of stainless steel by strong-field laser surface passivation