A close atomic surface of stainless steel produced by novel green chemical mechanical polishing using silica and lanthana mixed abrasives

Stainless steel poses machining challenges due to its corrosion and wear resistance. Traditional chemical mechanical polishing (CMP) often involves using noxious slurries, resulting in environmental risks. Moreover, surface roughness Sa is normally higher than 0.5 nm on stainless steel using conventional CMP, and the material removal rate (MRR) is extremely low. To address these challenges, a novel green CMP method was developed, which uses silica, lanthana, malic acid, γ-aminobutyric acid and hydrogen peroxide. Following this environmentally friendly CMP process, the surface roughness Sa of stainless steel was reduced to 0.286 nm, with an MRR of 82.14 nm min^-1. These results represent significant advancements compared to existing studies. X-ray photoelectron spectroscopy analysis demonstrates that hydrogen peroxide oxidized the surface of stainless steel, forming oxides. Malic acid then dissolved these oxides by releasing hydrogen ions. Meanwhile, γ-aminobutyric acid through its -COOH functional groups chelated Fe²⁺, Fe³⁺, and Cr³⁺ ions. This innovatively green CMP process suggests a fresh perspective on achieving fine surface roughness on stainless steel, simultaneously enhancing its wear and corrosion assistance. Its potential application in high-performance stainless steel devices is promising.