On 05. June 2015 at xx:15 in Physicums aud XXX will defend Madis Umalas his doctoral theses "Application of sol-gel technology for production of ceramic nanocomposites and functional coatings".
Dr Ants Lõhmus, University of Tartu, Institute of Physics
Dr Irina Hussainova, (Tallinn University of Technology).
Dr Rünno Lõhmus, University of Tartu, Institute of Physics
Dr Karin Mougin (Institut de Science des Matériaux de Mulhouse;, Prantsusmaa)
Dr Valdek Mikli (Tallinn University of Technology).
The conventional industry is undergoing a dramatic change towards an innovative, high-tech, knowledge-based grounds. Increasing competition on the global market constantly demands for materials with advanced properties and producing technology. During recent decades researchers have paid great attention to new materials that are stable at extreme environmental conditions as candidates for technological applications like supersonic flights and rockets. Metal carbides and oxides are promising candidates for extreme environmental conditions due to their excellent and unique combination of high melting point, good thermal-shock resistance and high hardness.
The particular aim of this thesis is related to elaboration of ceramic nanocomposites and functional coatings with desired properties by sol-gel method. It is chosen since in contrast to conventional ceramic materials synthesis methods, in sol-gel process reactants are mixed together in liquids at molecular level due to the synthesis conditions enabling to decrease synthesis temperatures and prepare homogeneous and pure multi component systems.
In particular, the thesis describes the synthesis of TiC-ZrC, TiC/CNT and AgNW/TiO2 nano-composites precursors. The problems of dispersion and thermal stability of filler material are treated. Moreover, the thesis reports mechanical characterisation of individual nanofillers like Al2O3 nanofibers and AgNW using advanced experimental set-up installed inside a scanning electron microscope. Development and construction of experimental equipment are also involved. As a part of the study, the thesis also includes development of experimental set-up, which was used for in situ SEM mechanical characterisation of individual one-dimensional nanostructures (1DNS) served as reinforcing phase or functional filler in the considered nanocomposites.