添加剂对碳热还原反应制备ZrB_2粒径及形貌的影响

Particle Size and Morphology of ZrB_2 Powder Prepared by Carbon Thermal Reduction Reaction with Additives

以ZrO_2,H_3BO_3和C粉为原料,利用碳热还原反应制备ZrB_2粉体。通过X射线衍射(XRD)分析粉体物相、扫描电镜(SEM)观察粉体形貌、能谱(EDS)分析粉体成分,并对粉体进行粒度和比表面积分析,研究了B粉、ZrB_2晶种、NaCl作为添加剂对ZrB_2粉体粒径及形貌的影响。结果表明:添加适量B粉可以提高ZrB_2的生成转化率,同时减小颗粒尺寸,得到细小的ZrB_2颗粒,当B粉添加量为5%时,粉体平均粒径最小,为4.8μm;随着ZrB_2晶种含量的增加,ZrB_2粉体平均粒径增大、比表面积减小,同时颗粒形貌趋于不规则,联接与团聚现象更加严重,当ZrB_2晶种含量达到15%时,粉体平均粒径最大,为7.3μm;在NaCl作用下,ZrB_2颗粒沿某一方向生长明显,颗粒尺寸显著增大,形貌呈长条状,并且随着NaCl含量增加,颗粒生长得更加粗大,当NaCl含量为15%时,粉体平均粒径增大至9.1μm。

ZrB2 powder was prepared by carbon thermal reduction reaction using ZrO2 , H3BO3 and C as raw materials. The phase structure of powder was measured by X-ray diffraction （ XRD）, the morphology of powder was observed by scanning electron micro- scope （SEM）, the composition of powder was analyzed by energy dispersive spectroscopy （EDS）, and the panicle size and specific surface area of powder were analyzed. The effects of B powder, ZrB2 seed and NaCl as additives on the panicle size and morphology of ZrB2 powder were studied. The results revealed that adding proper amount of B powder could increase the conversion rate of ZrB2 and reduce the particle size, and fine ZrB2 particles were obtained. When the addition amount of B powder was 5% （mass fraction）, the average particle size of powder was the minimum of 4.8 μm. With the increase of ZrB2 seed content, the average particle size of ZrB2 powder increased, and the specific surface area decreased. The morphology of particles tended to be irregular, and the phenomena of coupling and aggregation were more serious. When the content of ZrB2 seed reached 15% （mass fraction） , the average panicle size of powder was the maximum of 7.3 μm. Under the action of NaCl, ZrB2 panicles grew along a certain direction obviously, and the parti- cle size increased significantly, the morphology of particles was long strip. With the increase of NaCl content, the particles grew coarser. When the NaCl content was 15 % （mass fraction） , the average panicle size of powder increased to 9.1 μm.