| Popis: |
The aluminum-nickel system is well characterized as multilayer thin films, as well as in mechanical alloying. Normally, one obtains the multilayers by chemical vapor or physical vapor deposition. Mechanical alloying is based on ball milling of the individual metal powders, for different time and in different molar ratios. An equimolar mixture of Ni and Al powder yields a material, which can be ignited via a self-sustaining exothermic reaction, similar to self-propagating high temperature synthesis reactions. Al-Ni powders obtained by ball milling are therefore classified as high energy powders. An elegant and easy route to obtain Al-Ni multilayers or composites is electrodeposition. The standard electrode potential of Al(III)/Al(0) lies around -1.68 V vs. SHE (standard hydrogen electrode), while that of Ni(II)/Ni(0) is only of -0.26 V vs. SHE. Therefore, any attempt to obtain multilayers by electrodeposition is challenging, and would involve complexing chemistry. On the other hand, one can relatively easy co-deposit Al and Ni in ionic liquids, ILs, e.g., Al films with dispersed Ni particles, or Ni films with dispersed Al particles. In this study, Al and Ni particles were prepared from the gas phase directly in ILs. The experiments were performed in 1-butyl-1-methylpyrrolidinium-bis(trifluoromethylsulfonyl)amide under bubbling with nitrogen gas and inside a glove box (moisture and oxygen contents below 0.5 ppm). The co-deposition experiments were performed by cyclic voltammetry and potentiostatic depositions, in a temperature range from room temperature to 120°C. The morphology and composition of the layers were analyzed by SEM/EDX and optical microscopy and will be further discussed in this contribution. |
