Fabrication of titanium matrix composites by high pressure plasma spraying

Titanium matrix composites reinforced with continuous fibres are candidate materials for high performance structural components in aerospace applications. The present work has been focussed on the use of a fabrication methodology of composite monotapes alternative to the well known fibre-foil techniques. The same fabrication procedure was also selected to produce composite preforms suitable for secondary consolidation processes, as those based upon diffusion bonding methods, in order to obtain multilayered composites. To this purpose, the technical feasibility of using a plasma spraying technique was investigated and evidenced. Results in terms of optimised processing parameters are reported and discussed together with the adopted experimental methodology. Long SiC fibres (SCS6) and four different titanium matrix Ti-6Al-4V, Ti-4.5Al-3V-2Mo-2Fe, Ti-6Al-2Sn-4Zr-2Mo and Ti-15V-3Al-3Cr-3Sn were used. Spraying runs were carried out on a CAPS (Controlled atmosphere plasma spraying) equipment and optimum sprayi ng conditions, to enhance microstructural properties of the deposited matrix and to maximise interfacial shear strength, were identified in high pressure values in the spraying chamber. An appropriate control of deposition temperature was also required to minimise post spray residual stresses in the composite monotapes.