Effect of Na2B4O7 on ZrB2 Powder Prepared by Self-propagating High-temperature Synthesis
ZHANG Wei1, XIAO Guoqing1, DING Donghai1,2,3
1 College of Materials and Mineral Resources, Xi’an University of Architecture and Technology, Xi’an 710055; 2 Postdoctoral Mobile Research Station of Materials Science and Engineering, Xi’an University of Architecture and Technology, Xi’an 710055; 3 State Key Laboratory of Advanced Refractories, Sinosteel Luoyang Institute of Refractories Research Co., Ltd., Luoyang 471039
Abstract: ZrB2 powders were prepared by the self-propagating high-temperature synthesis (SHS) using ZrO2, Mg, B2O3 and Na2B4O7 as main raw materials. Based on thermodynamic calculation, the feasibility of the SHS was studied by FactSage7.0. The phase composition and microstructure of the final product were characterized with X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM) with energy dispersive spectrometer (EDS). The ZrB2 purity of the final product could be improved when the raw materials were mixed with extra amount of Mg and B2O3, it was found that the optimum extra amounts of Mg and B2O3 were 40wt% and 30wt%, respectively. Based on the optimum ratio, the effect of replacing B2O3 by Na2B4O7 on purity and microstructure of ZrB2 was studied. When the replacement ratio was 15%, the purity of ZrB2 was the best, the grain size of ZrB2 decreased from 2 μm to less than 0.5 μm with the increasing Na2B4O7 replacement ratio.
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2017, Vol. 31 
