稀释剂添加量对燃烧合成亚微米ZrB_2微观组织的影响

Effects of the Diluent Content on Microstructure of Submicron ZrB_2 by Combustion Synthesis

以NaCl为稀释剂,B2O3、ZrO2和Mg粉为原料,利用燃烧合成法成功制备了亚微米ZrB2粉体,并对其进行了SEM、EDS,XRD和粒度分析。结果表明:随着稀释剂添加量增加,体系绝热温度下降;浸出产物是由少量的大尺寸颗粒和大量的小尺寸颗粒形成的弱团聚体;稀释剂摩尔数k值从0.5增加到1.5时,产物平均颗粒尺寸从305 nm降低到160 nm;产物浸出后主要物相为ZrB2和ZrO2,后者含量随稀释剂添加量增加而降低。稀释剂可以提供液态介质,促进质量传输,提高产物纯度,还可以降低体系燃烧温度,并包覆在产物表面抑制其结晶长大,降低颗粒尺寸。

Submicron ZrB2 powders were prepared by combustion synthesis using NaC1 as the diluent and B203, Mg and ZrO2 as raw materials. The samples were analyzed by SEM, EDS, XRD and particle size analyzer. The results show that adiabatic temperature of the system decreases with the diluent content increase. The products are aggregates which contain a small amount of larger-sized particles and a large number of small-sized particles. The average particle size of products drops from 305 nm to 160 nm as the value of k, i.e. molar ratio of the diluent, increases from 0.5 to 1.5 The products after leaching mainly consist of ZrB2 and ZrO2, and the content of the latter decreases with the increase of k. NaC1 plays very important roles, such as providing a liquid medium, promoting the mass transfer, improving the purity of the products, reducing the combustion temperature of the system, inhibiting growth of particles by giving a coating on the surface, and leading to small-sized particles.