碳含量对盐助燃烧合成法制备的超细WC粉体形貌、尺寸和相的影响

Effect of Carbon Content on Morphology, Size and Phase of Submicron Tungsten Carbide Powders Prepared by Salt-assisted Combustion Synthesis

摘要:

在WO3-Mg-C-Na2CO3体系中，引入NaCl做稀释剂，通过盐助燃烧合成法制备了超细碳化钨（WC）粉体。利用扫描电镜（SEM）、能谱仪（EDS）和X射线衍射（XRD）对产物进行分析，研究了碳（C）含量对制备的WC粉体的形貌、尺寸和相的影响。结果表明：在m=0.125（Na2CO3的摩尔数）基础上，将原料中碳的摩尔数从l=2增加到2.25和2.5，浸出前产物由少量大尺寸颗粒及大量小尺寸颗粒组成；浸出后产物是由亚微米小颗粒团聚而成，颗粒之间熔化烧结现象很弱，呈弱团聚状态；浸出产物的粒度分布基本符合正态分布，尺寸在200～350nm的范围内；在l=2.25条件下，合成的产物主要为目标产物WC，副产物W2C含量极少。即k=2.0（NaCl的摩尔数），m=0.125，l=2.25为制备单相WC的工艺条件。

Abstract:

The Diluent NaCl was introduced into the WO3-Mg-C-Na2CO3 system (WO3, C, Mg powders and Na2CO3) to prepare submicron tungsten carbide (WC) powders via salt-assisted combustion synthesis. The products were analyzed by SEM, EDS and XRD, and effect of C content on morphology, average particle size and phase composition of the products were studied. The Results show that on basis of the m = 0.125 (the number of moles of Na2CO3), when the number of moles of carbon in raw material increases from l=2 to 2.25 and 2.5, respectively, before leaching, the product was made up of a small number of large size particles and a large number of small size particles; After leaching, samples were composed of aggregates of submicron particles, the fusion sintering phenomenon between particles was very weak, indicating low degree of aggregation. Particle size distribution of leached product almost falls into the normal distribution, and the particle sizes range from 200 nm to 350 nm. Under the condition of l=2.25, a main target product is WC, and content of by-products W2C is extremely few. That is, k = 2.0 (the number of moles of NaCl), m = 0.125, and l=2.25 are the process conditions for single-phase WC synthesis.