Polymer-derived Si-C-Ti systems: From titanium nanoparticle-filled polycarbosilanes to dense monolithic multi-phase components with high hardness

This paper describes the fabrication of Si-C-Ti ceramics from titanium nanoparticle filled allylhydridopolycarbosilanes (Ti NP-filled AHPCS) using a casting/curing technique followed by pyrolysis at 1000 °C under argon. TGA and XRD have been applied to investigate the mass loss behaviour during ceramization and to gain structural information on the decomposition process of Ti NP-filled AHPCS. TiC is the first phase to nucleate in an amorphous SiC matrix around 800 °C, whereas titanium silicide and MAX phases grow between 800 and 1000 °C. Densities measurements have been done and structural characterization of the final specimens is carried out using XRD and Raman spectroscopy. The process leads to (nano)composites with a density increasing from 2.45 to 2.90 g/cm3 and a Vickers hardness ranging from 17 to 20.9 GPa according to the AHPCS:Ti ratio fixed in the early stage of the process. The titanium silicide and MAX phases are decomposed during a further heat-treatment between 1000 and 1400 °C to generate TiC/SiC (nano)composites.