Synthesis and characterization of non oxide ceramic obtained by the thermal decomposition of polymeric precursors

There has been a substantial interest during the last years in polymer derived ceramics due to the wide array of interesting properties they exhibit. This type of ceramic, best known by the acronym PDCs, are obtained by the thermal decomposition of a polymeric precursor and are mainly non oxidic, such as SiC, Si3N4, BN, etc. PDCs exhibit a wide array of thermomechanical and electrical properties of great interest, as well as a high thermal and oxidation resistance which make them promising candidates for working under extreme environmental conditions. Thus, several potential applications ranging from nanotechnology to aeronautics have been proposed. A big advantage of these materials is that their properties depend on both the chemical properties of the original polymeric precursor and the processing conditions. Therefore, by carefully selecting the precursor and the experimental degradation conditions it would be possible to tailor the properties of the final ceramic. Moreover, the temperatures needed to prepare these ceramics are much milder than those required by means of conventional ceramic processing or powder consolidation techniques. However, there is an important disadvantage that has severely limited their usability in that cracks are formed during the transformation into a ceramic so that the final pieces might be rendered unusable. Despite the important of processing, there are few systematic studies assessing the influence of ceramification conditions on the final properties. In this proposal, we plan to use smart temperature controlled methods to study the synthesis of different types of PDC. This methodology allows for great precision in the control of experimental conditions such as temperature and gas pressure and has been previously proved useful to help control the microstructure of materials synthesized by thermal transformations from precursors. Thus, we plan to use this methodology to synthesise defect-free PDCs and to study the influence of experimental conditions on the nanostructure and properties of the final ceramic material. At the same time, the information provided by the systematic study will help to better comprehend the underlying physics of the as yet poorly understood polymer-ceramic transformation. The prepared powders will be characterised in terms of nanostructure and properties such of piezoresistivity, porosity, lithium insertion capability and oxidation resistance.