Preparation of Fe–Al Binary Thermoelectric Conversion Films by Electrodeposition in AlCl3–NaCl–KCl–FeCl2 Quaternary Molten Salts

Abstract

The electrodeposition of Fe–Al alloy in AlCl3–NaCl–KCl–FeCl2 quaternary molten salts was investigated by potentiostatic electrolysis to prepare Fe–Al alloy film with a thermoelectric conversion function. In the AlCl3–NaCl–KCl–FeCl2 molten salts with an AlCl3/FeCl2 mole ratio of 200 (FeCl2: 32.6 mmol l−1), the electrodeposited Al formed a solid solution with Fe in the potential range from 0.5 to 0.2 V vs Al(III)/Al and formed the intermetallic compound of Fe3Al at the potential of 0.1 V. Fe–Al alloys containing 0.8–34.5 mol% Al were obtained by controlling the AlCl3/FeCl2 mole ratio (FeCl2 concentration) in AlCl3–NaCl–KCl–FeCl2 molten salts and the applied potential in the potential range from 0.2 to −0.1 V vs Al(III)/Al. The Fe–Al alloy films prepared in the present study exhibited the p- or n-type thermoelectric conversion, depending on their composition.