Preparation of Al-Ni Alloy Coating in NaCI-KCI-AICl_3 Molten Salt

摘要

Al-Ni alloy coating was prepared on carbon steel sheet with the electro-deposition method by adding anhydrous NiCI_2 into NaCI-KCI-AICI_2 low-temperature molten salt. The morphology, composition and phase of the alloy coating are tested by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The electro-deposition mechanism of Al-Ni was studied by the test of cyclic voltammetry and chronoamperometry. The result showed that the Ni content in the Al-Ni alloy coating increases with the increase of NiCI_2 content and current density in molten salt. The increase of Ni content in Al-Ni alloy coating is beneficial to improving the morphology of the Al-Ni alloy coating, making the crystal grains smaller and denser. The Al-Ni alloy coating mainly contains Al phase and Al-Ni alloy phases. The deposition process of Al-Ni alloy in the molten salt system is a diffusion controlled reversible mass transfer process which can be completed in three steps. The deposition process is in accordance with the three-dimensional instantaneous nucleation process controlled by hemispheric diffusion.