Synthesis and formation mechanisms of nanocomposite WC–MgO powders by high-energy reactive milling
Synthesis and formation mechanisms of nanocomposite WC–MgO powders by high-energy reactive milling
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DOI：
10.1016/j.jallcom.2008.11.100
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发表时间：
2009-06
影响因子：
6.2
通讯作者：
Cao Wu;S. G. Zhu;J. Ma;Meilin Zhang
中科院分区：
文献类型：
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作者：
Cao Wu;S. G. Zhu;J. Ma;Meilin Zhang
以低成本的WO3、Mg和石墨粉为原料，在氩气气氛下进行行星球磨，在室温下制备了纳米复合WC-MgO粉末。采用x射线衍射（XRD）和透射电子显微镜（TEM）对粉末样品进行了表征。采用碰撞模型计算铣削能量，得到铣削能量图。得到的铣削能量图揭示了铣削参数（包括铣削速度、球粉重量比和铣削时间）对形成机理的影响。结果表明，当有效延伸因子Ebis大于38.24kJg−1s−1时，可以通过自传播高温合成（SHS）生成WC-MgO；当有效延伸因子Ebis在22.12kJg−1s−1 ~ 38.24kJg−1s−1之间时，也可以通过逐渐反应生成WC-MgO。正如能量图所示，通过SHS制备WC-MgO所需的总能量范围为25.61×106kJg−1至61.82×106kJg−1，而渐进反应一所需的总能量大于112.83×106kJg−1。这些铣削能量图是为了更好地理解高能反应铣削合成和形成WC-MgO的工具。
The nanocomposite WC–MgO powders were prepared at room temperature by reactive milling of low-cost WO3, Mg and graphite powders under argon gas atmosphere in a planetary ball milling. Powder samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The milling energy was calculated using a collision model and the milling energy maps were attained. The effects of milling parameters (including milling speed, ball-to-powder weight ratio and milling time) on the formation mechanism have been illuminated by the obtained milling energy maps. Results show that WC–MgO can be formed via Self-propagation High-temperature Synthesis (SHS) when the effective extensive factor Ebis above 38.24kJg−1s−1, and it also can be formed from gradual reaction when Ebis between 22.12kJg−1s−1and 38.24kJg−1s−1. As the energy map demonstrates, the total energy Etrequired for fabricating WC–MgO through SHS ranges from 25.61×106kJg−1to 61.82×106kJg−1, while more than 112.83×106kJg−1is necessary for gradual reaction one. These milling energy maps are proposed as a tool for better understanding of the synthesis and formation of WC–MgO by high-energy reactive milling.