Effects of Molten Salt on ZrO2 Fibers Template Assisted Combustion Synthesis of ZrB2 Fibers
XIAO Guoqing1, ZHOU Pan1, 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: The short ZrB2 fibers were synthesized by template assisted combustion synthesis, taking ZrO2 fibers, Mg and B2O3 as raw materials, NaCl, MgCl2 and their compound salts as diluents. The adiabatic temperature of the systems was calculated by trial method. The effects of molten salt content on the phase composition and micromorphology of the products were investigated by XRD and SEM, respectively. The results showed that the adiabatic temperature decreased with the increment of molten salt content. The adiabatic temperature drop of the system with NaCl was more obvious, especially in high molten salt content condition. The NaCl added samples comprised of ZrB2 and small amounts of residual ZrO2. Small amount of Mg3B2O6 was found in the sample added with MgCl2. The addition of molten salt could prevent the ZrO2 fibers from melting and make it easier for product to maintain the shape of original fiber. The crystallite size of the product could be reduced by NaCl and MgCl2 in the systems. MgCl2 could promote the crystallization of ZrB2 and they grew into the hexagon crystals of clear boundaries with the increasing content of MgCl2. From the analysis of residual ZrO2 and grain size, the effect of single salt was superior to compound salt, and MgCl2 was more effective than NaCl.
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