سنتز صفحات زیرکونیوم براید از مخلوط پودر ZrCl4 و B فعال شده به صورت مکانیکی

Synthesis of zirconium diboride platelets from mechanically
activated ZrCl4 and B powder mixture

سنتز صفحات زیرکونیوم براید از مخلوط پودر ZrCl₄ و B فعال شده به صورت مکانیکی

 

ABSTRACT

In summary, the platelet-like ZrB2 particles were successfully prepared by the mechanochemical processing of a ZrCl4– B mixture and subsequent annealing from 1000 8C to 1200 8C. ZrO2 was identified as the possible intermediate reaction product. At 1000 8C, the ZrCl4–B mixture transformed to ZrB2 by a reaction between ZrO2 and B that accompanied the hydrolysis reaction of ZrCl4 following the dehydration of zirconium oxide halides to ZrO2 upon heating. Trace quantities of unreacted ZrO2 were detected at 1000 8C and 1100 8C. At1200 8C, the ZrCl4–B mixture completely converted to ZrB2 without the presence of any residual ZrO2. The resulting ZrB2 powder consisted of platelet-like particles with a diameter of ۰٫۱–۲٫۱ mm, a thickness of 40–۲۰۰ nm and traces of whiskers.Also, another study of the borothermal reduction of ZrO2 and B powder mixture showed that ZrB2 was prepared by the mechanochemical processing and subsequent annealing at 1100 8C instead of 1700–۲۰۰۰ ۸C without mechanical treatment [19]. The direct synthesis of ZrB2 at lower temperatures was mainly attributed to the increased chemical mixing as well as concentration of defects in the ZrO2 grains during milling. A similar explanation is favoured in this study because the ZrO2 obtained upon heating of ZrCl4 showed many defects.