Electrodeposition of Al-Ti Alloy from Chloroaluminate Bath

Al-Ti alloy-electrodeposition in AlCl3-NaCl-KCl eutectic molten salt bath at 200°C has been studied using a flowing cell. The Ti content in deposited film increased with addition of TiCl3, and smooth deposit of Al-40.2%Ti was obtained at current density as high as 2000A/m2. The crystal structure of deposited films were found to change from cubic-Al, tetragonal-Al3Ti to tetragonal-AlTi with an increase in Ti content. Ti could not co-deposit unless Ti2+ was in bath, therefore, the addition of Al powder, which reduced Ti3+, was necessary. Electrochemical behavior of the Ti ion in the bath was studied by the electrochemical polarization technique. The reduction of Ti3+/Ti2+ (0.4V, vs. Al) and Ti2+/Ti0 (0.05V, vs. Al) were observed. Furthermore, a process using TiCl4 gas as the Ti source was demonstrated. Consequently, it can be considered that this molten salt electroplating system is one of the most feasible methods of producing Al-Ti alloy electroplated products.