THE PREPARATION OF THE MULLITE‒TIC‒TIN MATERIALS BY MEANS OF THE SPARK-PLASMA METHOD AND THEIR PROPERTIES

Abstract

The TiC and TiN powder's phase composition, their microstructure, relative density, open porosity, linear shrinkage, elasticity module, Vickers hardness number, ultimate compression strength were investigated as well as the elasticity module's and the ultimate compression strength's linear dependencies of the mullite‒TiC‒TiN samples with various TiC and TiN ratio,  sintered by means of spark-plasma method in the temperature range of 1200‒1600 оС under the pressing load of 30 MPa were defined. The synthesized powders are specified by the intensive crystallization of TiC and TiN. The synthesized samples with various TiC and TiN ratio show the intensive mulliization in the temperature range of 1200‒1600 оС. The samples with the TiC/TiN ratios of 50/50, 70/30 and 90/10 molecular percents show the gradual rise of TiC between 1200 and 1400 оС comparing to the more intensive increasing of TiC between 1200 and 1600 оС. The increasing of TiC concentration and the decreasing of TiN content in the sintered at 1500 оС powder mixtures promote the forming of the even highly densely-sintered microstructure with small size pores. The samples with the TiC/TiN ratio of 50/50 and 70/30  molecular percents show the more intensive relative density increasing, open porosity decreasing, and the augmentation of the elasticity module, Vickers hardness number and ultimate compression strength. This leads to the hardening against the cracks formation in the samples with the relatively straight microcracks appearing (the M50TiC50TiN composition) and to the micro-cracks absence (the M70TiC30TiN composition) around the indentations, the elasticity module's and the ultimate compression strength's linear dependencies being maximal in the temperature range of 1200‒1600 оС. Ill. 7. Ref. 12. Tab. 1.