A novel immersion chemical mechanical polishing device and tailored slurry for processing heavy duty gas turbine compressor blades

As a key component of heavy-duty gas turbines, the compressor blades typically have complex free-form surfaces. These blades are widely made of martensitic stainless steel, which has excellent high strength, high corrosion resistance, and wear resistance, making it a typical difficult-to-machine material. To address these challenges, a novel green chemical mechanical polishing (CMP) slurry has been developed. Its components include silica, zirconia, malic acid, hydrogen peroxide, and ethylenediaminetetraacetic acid disodium salt (EDTA-2Na). By applying this environmentally friendly CMP process, the surface roughness (Sa) of the stainless steel is reduced to 0.271 ± 0.04 nm, and the material removal rate reaches 127.11 nm/min. To verify its practical application effect, this formulation was applied to the polishing of compressor blades using an immersion CMP equipment. Finally, a surface roughness of 103.0 ± 0.5 nm was achieved, and the material removal rate reached 650.67 nm/min. The thickness of the damaged layer after polishing decreased to 28.78 nm. Results from both scanning electron microscopy and transmission electron microscopy indicated no chemical residues and no abnormal elemental enrichment after polishing.