Processing of Ti/SiC composites: a comparative study of the foil-fibre-foil and the tape-casting techniques

Abstract

Ti-based SiC fibre reinforced composites are strong, stiff and light-weight materials for high temperature applications up to 600-800°C. As with any other advanced materials, their development has to overcome both economic and technical hurdles. Here, a study into the foil-fibre-foil and the tape-casting processing techniques is reported. The fundamental procedures involved in the techniques are compared and discussed. Possibilities of reducing product costs are analysed. Fibre-matrix lay-up conditions to achieve uniform fibre distribution in fully consolidated composites have been determined. Both techniques are capable of producing uniformly distributed composites within 1 hour under a uniaxial pressure of 20-50 MPa at temperatures around 870 to 950 °C. In Ti-based materials studied to date, it appears that the interfacial reaction is slower in a more heavily alloyed matrix. For the pure titanium matrix, the reaction rate with various available reinforcements differs by one order of magnitude, with pure C-coating the most reactive and stoichiometric TiB2the least reactive. Hydrogen as a temporary alloying element in the titanium based materials effectively reduces the processing temperature and/or time. Interfaces of hydrogen-treated composites show little signs of reaction in both foil-fibre-foil and tape-casting processed samples, involving either pre-hydrogenated foils or hydride particles during processing.