5-Methyl-1H-Benzotriazole as an Effective Corrosion Inhibitor for Ultra-Precision Chemical Mechanical Polishing of Bearing Steel

5-methyl-1H-benzotriazole was used as an effective corrosion inhibitor in acidic H2O2-based slurries for ultra-precision chemical mechanical polishing (CMP) of a high carbon chromium GCr15 bearing steel (AISI 52100). The CMP performance of GCr15 steel and the corresponding corrosion inhibition mechanism of 5-methyl-BTA were thoroughly investigated. The CMP results reveal that, compared with 1,2,4-triazole, 1,2,3-triazole and BTA, 5-methyl-BTA achieves the best corrosion inhibition performance, and the surface roughness Ra of GCr15 steel greatly improves, which can be attributed to the triazole and hydrophobic methyl functional groups. In synergy with H2O2, 5-methyl-BTA can be both chemically and physically adsorbed on the GCr15 steel surface in acidic medium. Specifically, the chemical adsorption mainly occurs by chemical reactions between 5-methyl-BTA and iron of GCr15 steel to form a surface complex. In the presence of 1.0 wt% H2O2 and 20 mM 5-methyl-BTA, the sparse corrosion inhibition film formed by 5-methyl-BTA together with the dense oxide film constitutes a complete passivation film, eventually resulting in the nanoscale planarization. The results can provide a guide for the selection of appropriate nitrogen-containing corrosion inhibitors for bearing steels CMP.