Effect of Calcination Conditions on Synthesis of Ultrafine ZrB2 Powder by Sol-Gel Method
ZrB2-based ceramics have broad application prospects in the field of ultra-high temperature.ZrB2 powders are pre-pared by sol-gel method with zirconium propanol,sucrose and boric acid as Zr,C and B sources,respectively,and the effects of calcination temperature,holding time and argon flow rate on the synthesis of ZrB2 powder are studied.The results show that with the increase of calcination temperature,the content of impurity phase in the product decreases gradually,and that the con-tent of ZrB2 phase increases gradually.Pure ZrB2 powders are obtained by holding the precursor powders with a molar ratio of 2.85∶1∶7 of B∶Zr∶C in argon atmosphere at 1 550 ℃ for 30,60 and 120 minutes.The average grain size of ZrB2 powders calculated by Scherrer formula is much smaller than that observed by SEM,indicating that the ZrB2 powders are composed of small grains.The argon flow rate during calcination process will affect the volatilization degree of B2O3,and then affect the phase composition of the product.
ZrB2sol-gel methodcalcination temperaturemicrostructurevolatilization of B2O3
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