SYNTHESIS OF THE ZrN–ZrВ2 COMPOSITE BY SPARK PLASMA SINTERING

   

I. M. Frantsevich Institute for Problems of Materials Science of the NAS of Ukraine, Omeliana Pritsaka str.,3, Kyiv, 03142, Ukraine
Powder Metallurgy - Kiev: Frantsevich Institute for Problems of Materials Science NASU, 2019, #07/08
http://www.materials.kiev.ua/article/2859

Abstract

Reactive spark plasma sintering of ZrH2, BN, and B powder mixtures in the temperature range 1500–1900 ºC was used to produce a ZrN–ZrВ2 ceramic composite with 35–80 wt.% ZrВ2. The phase transformations in the temperature range 900–1900 ºC, the nature of densification at 1800 ºC, and the effect of composition and sintering temperature on the mechanical properties of the sintered composites were examined. The densification process proceeds in four stages at a sintering temperature of 1800 ºC. At the first sintering stage, ZrH2 dehydrogenation begins with the release of atomic (molecular) hydrogen (before the time dependence of shrinkage becomes S-shaped). The second stages involves chemical reactions in the system. At the third and fourth stages, synthesized ZrN and ZrB2 are sintered directly. The zirconium–boron interaction proceeding through self-propagated high-temperature synthesis influences the densification and final structurization of the composites. As a result, the highest mechanical properties are exhibited by the samples with 80 wt.% ZrB2 sintered in the range 1800–1900 ºС.


ATOMIC HYDROGEN, MECHANICAL PROPERTIES, SPARK PLASMА SINTERING, ZRH2 DEHYDROGENATION, ZRN–ZRВ2 COMPOSITE