Mechanism of the Single-Crystal Tungsten Whiskers Growth in the Process of the NiWO(4) Reduction by CO

作者：Karpovich Nataliya F; Lebukhova Nataliya V^*; Zavodinsky Victor G; Makarevich Konstantin S

来源：Journal of Physical Chemistry C, 2008, 112(47): 18455-18458.

DOI：10.1021/jp805430b

Experimental evidence is presented that the growth of tungsten whiskers in the process of the NiWO(4) reduction by carbon oxide occurs in accordance with the vapor-liquid-solid mechanism. A liquid phase appears at 940 degrees C owing to the melting of the NiWO(4)-Na(2)WO(4) eutectic regions which are perhaps results of segregation of sodium impurities included in the reagents used. The presence of the liquid phase ensures for both Ni and W the comparable rates of allocation from the nickel tungstate crystal lattice leading to the formation of the alpha-W + NiW two-phase regions. The oriented growth of tungsten whiskers during the further reduction of the melt tungstate zones is associated with the W accumulation on the growth surfaces of the W single crystals in the two-phase regions. The result demonstrates that the reactivity of NiWO(4) increases with addition of CuO and Na(2)WO(4) which are capable to form easy-melting phases in the reactive system.

• 出版日期2008-11-27