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Microstructure and hardness of TiB2
Halasová, Martina ; Bača, L. ; Šajgalík, P. ; Chlup, Zdeněk ; Dlouhý, Ivo
MICROSTRUCTURE AND HARDNESS OF TIB2 TiB2 in its pure form is extremely hard material with high melting point. This behaviour predetermines it to be used as e.g. nozzles, armour or wear parts. It is also very brittle and the effort is to decrease brittleness trough addition of various dopants. This contribution deals with the TiB2 dopped with Ta and Ni in various ratio. For observing the microstructure was used SEM and Vickers hardness was calculated by measuring the diagonals of indents. For comparison the values obtained by machine were shown in graph, too.
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Evaluation of properties of pyrolysed resins
Halasová, M. ; Chlup, Zdeněk ; Strachota, Adam ; Černý, Martin ; Dlouhý, Ivo
The presented work describes mechanical properties of materials prepared by pyrolysis of polysiloxane resins. The polymeric precursors had different chemical composition. Materials under investigation are predetermined as a matrix for high temperature resistant long fibre composites. An instrumented hardness tester was employed for materials characterisation. The Vickers hardness, Martens hardness and indentation elastic modulus were the key parameters determined from the load-indentation depth curves. Influence of the mechanical properties on the ratio of T and D was established. Indents were observed by using confocal laser microscope.
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