An exploratory study of electrodeposition of titanium using titanium dioxide carbon composite anode and molten aluminium cathode

Abstract

The objective of this study is to deposit titanium metal on a molten metal pool of aluminium, by electrochemical reduction in titanium oxide, which is in the form of titanium dioxide carbon (TiO₂–C) composite used as anodes in fused alkali chlorides. TiO₂–C composite blocks were prepared by compaction. It was backed at 873–1073 K for 48 h. It is noticed that density, porosity and electrical resistivity of the blocks are increased with increase in TiO₂ content. Electrochemical characteristics, namely I–V characteristics were studied using TiO₂–C composite blocks as anode, molten aluminium as cathode in molten alkali chlorides. Electrolysis experiments were conducted using TiO₂–C composite as anode and molten aluminium as cathode in the chloride melt at ∼1073 K. It is observed that the dissolution of anode blocks containing 70% titanium oxide were very smooth. At anode, the oxygen ion from the lattice of the TiO₂ comes out and combines with carbon (anode) to form carbon monoxide and carbon dioxide. In the bath, the titanium ion forms multivalent titanium chlorides (in situ) or titanium complexes with chloride ions. At cathode, titanium chlorides/complexes, which are formed in situ, dissociate as titanium ions and reduce to titanium particles. These particles deposited on the molten aluminium cathode and sink into it. The aluminium samples sectioned from the chilled electrolytic cell were undergone for chemical analysis and microscopic investigations. The micrographs of optical and SEM revealed the presence of dendritic needles of titanium rich phase in the aluminium matrix. The EDAX analysis on the needle shaped particles showed the formation of TiAl₂ phase. The Faradic current efficiency of this process was 10–30%.