Electrolytic Production Route for Affordable Titanium Matrix Composites

Abstract

In spite of their outstanding thermomechanical properties and many years of intensive material engineering efforts, silicon carbide-fibre reinforced titanium composites could not be applied on a large industrial scale due to their high production costs. The fabrication of Ti/SiC-fibre-MMCs is currently carried out by hot isostatic pressing (HIP) of PVD-coated Ti/SiC-fibres (matrix coated fibre process - MCF) or hot pressing of SiC filaments between titanium alloy foils. In various material tests it has been demonstrated that the MCF production route is the most convincing with respect to the mechanical properties. Considering this process there are two potential factors to realise cost reduction: The coating process and the material costs of the titanium alloys. Both possibilities are investigated in a public funded corporate project of IME (RWTH Aachen University) and DLR (German Aerospace Center). Alternative processes could come to operation either independently or in combination. The Ti-coating may be achieved by a cathodic electrodeposition of titanium ions from alkali molten salt mixtures. The same molten salt mixtures can be used to develop a cost efficient production route for titanium from titanium dioxide. A titanium dioxide-carbon-anode will be used to reduce Ti(IV) to Ti(II) and to transfer it into the molten salt. No chlorine gas evolves as the Cl-ions are immediately reused for Titanium chlorination (in situ process). Pure titanium will be obtained by the subsequent electroreduction step. After studying each electrode system by itself and taking into account that the electrochemical parameters (bath composition, temperature, electrical parameters, etc.) should be compatible, attempts will be made to combine the processes to one cost efficient and fast step within the Ti-MMC production route. The poster presents the methodology of the experimental work, the complex reaction mechanisms behind it and results received from the first years work.