Co-synthesis of zirconium boride/silicide/oxide composite powders by magnesiothermic reduction

Abstract

This study uses a magnesiothermic reduction method to investigate the co-synthesis of zirconium boride, silicides, and oxide powder composites using ZrO2, B2O3, Si, and Mg initial powders. The synthesis of high-temperature ceramic powders is examined through milling durations, reduction temperatures, and excess magnesium addition. Thermochemical analysis of probable reaction products was conducted by the Factsage software. According to the results, the thermochemical predictions and resultant powder phases showed good coherency. High-energy milling has a significant effect on the formation of the zirconium boride phase after annealing. However, extended milling time and higher annealing temperature have no significant effects on the composition of the constituted composite powders according to the X-ray diffraction results. An annealing temperature of 600 ºC was enough to obtain ZrB2-based ceramic composite powders. In the final powder phases, the excess magnesium addition to the stoichiometric displays an important feature. After the milling, annealing, and leaching procedure, the stoichiometric powder composition comprises ZrB2, ZrSi, ZrSi2, ZrO2, and MgSiO2, and excess Mg added powders have the ZrB2, ZrSi, ZrSi2, ZrO2 phases in their structure. Scanning electron microscopy analysis was utilized to observe the morphologies of the powders throughout each step of the synthesis procedure and revealed the finely structured morphology of synthesized powders.