BROŽEK Vlastimil Institute of Chemical Technology Prague

Spoluautoři PALA Zdenek, VILEMOVA Monika, KUBATIK Tomas Frantisek, MUSALEK Radek, NEVRLA Barbara, MASTNY Libor

First reference about existence of ultrahard composite in the TiC-ScCx system was made by G.V. Samsonov in the year 1962. Further research performed on ICT Prague and University of Vienna proved a discrepancy in the structure and stoichiometry of scandium carbide. Analogously to cubic carbides and nitrides of 3rd period metals, Scandium was also expected to have extreme hardness, high chemical stability and to enable solid solution formation (Vegard rule) with controlled regulation of physical parameters. Higher hardness of the cubic carbides is related to the decrease of lattice parameter, thus is was expected that smaller atomic radius of Sc in TixSc1-xC solid solution will lead to increase in hardness. However it was discovered that scandium carbide differs chemically as well as structurally, e.g. Sc15C19 is hydrolyzed and the product of the reaction is hydrogen, allylen and other carbohydrates. Thus for further hardness improvement, chemically stable ScN is commonly used nowadays. Due to high price of Sc compounds, CVD and PVD layers of TiAlN or TiScAlN on sintered carbides were used. In this work, reaction of TiC with metallic Scandium in the Spark Plasma Sintering process was studied. The product was a very hard and stable composite material leading to significant improvement of the current knowledge about scandium containing carbides and, moreover, facilitating new analyses of selected physical properties.