An atomic level surface fabricated using a developed polisher for martensitic stainless steel using novel chemical mechanical polishing

Abstract

Martensitic stainless steel has corrosion and wear resistance, making it a difficult-to-machine material. As a result, the surface roughness S_a of martensitic stainless steel is usually more than 0.5 nm after chemical mechanical polishing (CMP). To solve this challenge, a novel green CMP method was developed using a custom-made polisher, and the new environmentally friendly slurry includes lanthana and silica abrasives, hydrogen peroxide, citric acid and disodium ethylenediaminetetraacetic acid. After CMP, the surface roughness (S_a) of martensitic stainless steel is 0.183 nm. To the best of our knowledge, S_a is the lowest on martensitic stainless steel compared with those published previously. Molecular dynamics simulations indicate that when the nanoscratching depth is 7 Å, the thickness of the damage layer is 2.002 nm, which is in good agreement with that (2.01 nm) measured by transmission electron microscopy. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy reveal that hydrogen peroxide oxidized the surface of martensitic stainless steel, forming iron and chromium oxides, etc. Citric acid dissolved the oxides through coordination between carboxyl groups and metal ions. Disodium ethylenediaminetetraacetic acid chelated with trivalent iron ions and chromium hydroxides. Our outcomes pave a new way to fabricate an atomic level surface on martensitic stainless steel, using a new environmentally friendly slurry and CMP.