2012

Silicon carbide multilayer composites containing short carbon fibres (Csf/SiC) were prepared by tape casting and pressureless sintering. The C fibres were dispersed in solvents with dispersant (Triton X-100) firstly and then mixed with the SiC slurry to make green Csf/SiC tapes. Fibres were homogeneously distributed in the tape and tended to align fairly well along the tape casting direction. The addition of short C fibre hindered the shrinkage in the plane containing the fibres as well as the grain growth of SiC during sintering.

The thrust and efficiency of turbine engines are directly related to the operating temperature. In order to increase temperature without damaging the metallic parts of the engine, thermal barrier coatings (TBC) made of thick ceramic layers are currently deposited on the surface of high pressure turbine blades and vanes of aero engines. However, in the hostile engine environment, the TBC is subjected to degradation phenomena that limit its reliability and time of life. Thus, the comprehension of the TBC degradation process in this aggressive environment entails the greatest importance.

Third generation γ-TiAl alloys with a high niobium content, Ti–(47–48)Al–2Cr–8Nb, were processed by electron beam melting (EBM). This near-net-shape additive manufacturing process produces complex parts according to a CAD design. The starting powder is deposited layer by layer on the building table and selectively melted to progressively form the massive part. The EBM parameters such as layer thickness, melting temperature, scanning speed, or building strategy were set up to minimize porosity.

In this work, thermal degradation of commercial polymer mixtures was evaluated as a promising approach to the production of ceramic brake components. Currently, there is a wide interest for the production of cost effective ceramic pads, and carbon based materials are good candidates both in monolithic form and as porous networks to be reinfiltrated with a convenient polymer. The process parameters for obtaining porous glassy carbon, starting from mixtures of commercial polymers, have been evaluated in this work with the goal of producing samples with optimized mechanical properties.

In view of the possible application of SiC-based ceramic laminates as critical components of hydrogen generation plants based on sulfur-iodine or hybrid-sulfur thermochemical cycles, the effect of corrosion on this kind of ceramics has been investigated.