Electrodeposition of Titanium on SiC-Fibres for Metal Matrix Composite Production

Abstract

Titanium Matrix Composites (TMC) exhibit exceptional mechanical properties making them very well suited for aerospace applications where high specific strengths and stiffnesses are requested [1]. The production of high quality TMC is realised by processes in which silicon carbide monofilaments are coated with titanium alloys. Due to cost reduction efforts a molten salt based process is proposed and investigated as alternative to magnetron sputtering. It is known since many decades that it is impossible to deposit titanium from aqueous media [2]. However, electrodeposition of titanium from fused salts is also not without difficulties impeding industrial applications until now. In the presentation it will be demonstrated that dense coherent coatings can be deposited from molten LiCl-KCl with about 1 mol-% TiCl2. This is remarkable because it is often pointed out in literature that the presence of fluoride is a necessary condition to obtain coherent deposits, while in pure chloride melts dendrite, powder or sponge formation are favoured [3, 4]. Electrochemical measurements show that under the chosen conditions the deposition process is quasi-reversible. Nucleation studies confirmed a good surface coverage from the very beginning of the deposition process which is also supported by microanalytical investigations of cross sections.