Enhancing the long-term anti-corrosion property of Mg alloy by quaternary phosphonium salt: Integrated experimental and theoretical approaches

The corrosion resistance of two ionic liquids, [BPP][NTf2] and [OTP][NTf2], for Mg alloys is explored in NaCl solution by electrochemical approach, SEM, XRD, and XPS measurements along with theoretical calculations. The inhibition efficiency of [BPP][NTf2] is better than that of [OTP][NTf2] in three tested NaCl solution. Their inhibition performance is improved after long time immersion. Moreover, the [OTP][NTf2] would exceed [BPP] [NTf2] after 96 h immersion. The essential item to affect the long-term inhibition performance is elucidated by the molecular dynamics simulations. The possible inhibition mechanism is proposed according to the XPS results along with the quantum chemical calculations.

Automated summary

The corrosion resistance of two ionic liquids, [BPP][NTf2] and [OTP][NTf2], for Mg alloys in NaCl solution was explored, with [BPP][NTf2] showing better inhibition efficiency than [OTP][NTf2]. The inhibition performance of both liquids improved after long time immersion, although [OTP][NTf2] exceeded [BPP][NTf2] after 96h immersion. Molecular dynamics simulations elucidated the key factors affecting long-term inhibition performance, leading to a proposed inhibition mechanism based on XPS results and quantum chemical calculations.