NaCl含量对盐助燃烧合成超细硼化钨粉体相组成和粒度的影响及其作用机制

Effect and Action Mechanism of NaCl Content on Phase and Size of Submicron Tungsten BoridePowders by Salt-assisted Combustion Synthesis

摘要:

在W-B₂O₃-Mg体系中引入不同含量的稀释剂NaCl,盐助燃烧合成了超细硼化钨粉体,利用XRD、SEM和EDS对合成粉体的相组成及粒度进行了分析。结果表明未加入NaCl时,燃烧合成产物浸出前主要是W₂B₅和MgO的混合团聚物,颗粒形貌接近于椭球形；加入NaCl后,除了W₂B₅和MgO外,还出现了新相WB,颗粒形貌不规则且有微弱团聚现象；浸出后产物主要由大量的小尺寸硼化钨颗粒组成,粉体组成由W₂B₅转变为W₂B₅+WB+B的复合物。浸出产物W与B元素的总含量均达到了98%以上,当NaCl含量k=5时达到了最大值98.51%；其平均粒度随NaCl含量的增加而减小,当k=20时达到粒度的最小值0.85μm。

Abstract:

The diluent NaCl was added into the W-B₂O₃-Mg system to prepare submicro tungsten boride powders via salt-assisted combustion synthesis. The products were analyzed by XRD, SEM and EDS, and the effect of NaCl content on phase composition, morphology and average particle size of the products were studied. Results show that the combustion synthesis products before leaching mainly consisted of W₂B₅ and MgO, and the morphology of particles was similar to ellipsoid when without adding NaCl. After adding NaCl, combustion synthesis products before leaching mainly consisted of W₂B₅, MgO, WB and B, and the morphology of particles were irregular and particles were slightly reunion together. The products after leaching were composed of small size tungsten boride particles, the average grain size decreased with the increasing of NaCl contents, when the content of NaCl k=20, the smallest particle size was 0.85μm. The purity of products after leaching was higher, the content of W and B were up to more than 98%. The biggest content walue of W and B was 98.51% when the content of adding NaCl was 5%.