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以蒸发结晶法制得的仲钨酸铵为原料,制备了三氧化钨、蓝色氧化钨、WO_(2.72)、二氧化钨以及 WO_(2.72)-WO_2混合物和WO_2-α-W混合物的样品,用扫描电镜进行了形貌研究。对用固态合成法制备的WO_(2.72)与用氢还原法制备的WO_(2.72)作了形貌比较,说明两者共有的柱状晶是WO_(2.72)的固有晶形,不一定与气相迁移反应有关。氢还原钨粉的粒度在颇大程度上取决于二氧化钨的粒度。从蓝色氧化钨或WO_(2.72)到二氧化钨这一还原阶段,对钨粉粒度具有决定性影响。WO_(2.72)到二氧化钨及二氧化钨到钨粉的还原,并非按核收缩反应模式,还原反应是从假颗粒内外的活性点开始向周围扩展的。
Samples of tungsten trioxide, blue tungsten oxide, WO_ (2.72), tungsten dioxide, and mixtures of WO_ (2.72) -WO_2 and WO_2-α-W were prepared from ammonium paratungstate prepared by evaporative crystallization and characterized by scanning electron microscopy The morphology was studied. Morphology comparison between WO_ (2.72) prepared by solid-state synthesis method and WO_ (2.72) prepared by hydrogen reduction method shows that the columnar crystals shared by both are inherent crystal forms of WO_ (2.72), which are not necessarily related to gas phase migration reaction related. The particle size of the hydrogen-reduced tungsten powder depends to a large extent on the particle size of the tungsten dioxide. The reduction stage from blue tungsten oxide or WO2 (2.72) to tungsten dioxide has a decisive influence on the grain size of the tungsten powder. WO2 (2.72) to tungsten dioxide and tungsten dioxide to tungsten powder reduction, not according to the nuclear contraction reaction mode, the reduction reaction from the inside and outside the pseudo-particle activity point to the surrounding expansion.