Influence of mechanical grinding on the formation of native passive layers on aluminum alloys

Mechanical grinding creates mechanical as well as thermal stress in treated material and the so-called Beilby layer is formed. The present work investigates the influence of abrasive coarse grain size on the thickness and electrochemical behavior of the native oxide layer formed after the grinding process by using cyclovoltammetry. The difference in the native oxide layer thickness amounts to Δd ≈ 0.5 nm under the surface conditions investigated. Additionally, an experimental design is introduced and tested, which allows the operando measuring of the temperature of the material during the grinding process. Estimates result in a thermal stress Δσ between 0.8 and 1.3 MPa depending on the chosen grinding parameters and influence the subsequently formed oxide layer thickness.