WO_(2.90)(四方晶型)纯组分蓝色氧化钨氢还原动力学及超细钨粉制取的新方法

KINETICS STUDY ON HYDROGEN REDUCTION OF PURE BLUE TUNGSTEN OXIDE WO_(2.90)AND THE NEW PROCESS FOR PREPARATION OF ULTRAFINE TUNGSTEN POWDER

本文借助差热热重分析的方法研究了纯组分四方晶型 WO_(2.90)蓝色氧化钨氢还原动力学,并在此基础上探讨了利用新型钨酸盐 ART 热分解制备纯组分蓝钨并进一步氢还原制备超细钨粉的新工艺.研究结果表明,WO_(2.90)蓝钨高温氢还原经历两个阶段,分别受扩散控制及化学反应控制,表观活化能分别为13.9kJ/mol及65.8kJ/mol,还原温度、氢气流量及装料量都对反应速度有明显影响.在动力学研究基础上,提出以纯组分 WO_(2.90)蓝钨为原料氢还原制备平均粒径小于1μm的超细钨粉的工艺条件:温度700-850℃,还原时间3小时以上,氢气流量3m^3/h,露点-40℃以下,蓝钨料层厚度30mm 以下.本文研究结果对认识蓝钨还原过程及确定新工艺制取超细钨粉的工艺条件具有指导意义.

The kinetics of hydrogen reduction of pure component blue tungsten ox- ide(tetragonal WO_(2.90))was studied in this paper in terms of DTA-TG(differential thermal analysis-thermogravimetric analysis)method,and then the new process,thermally decom- posing new type tungstate to prepare pure blue tungsten oxide WO_(2.90)followed by further hydrogen reducing WO_(2.90)to produce ultrafine tungsten powder was also discussed.The re- sults indicated that in the course of hydrogen reduction of WO_(2.90)at high temperature there were two procedures which was controlled by diffusions and chemical reaction separately and with apparent activation energy 13.9kJ/mol and 65.8kJ/mol respectively,and that the reduc- tion rate was obviously affected by reduction temperature,flow rate of hydrogen and charge weight of blue tungsten oxide.On the basis of kinetic studies,the conditions for preparing ultrafine tungsten powder(mean particle size smaller than 1μm)by hydrogen reduction of pure blue tungsten oxide WO_(2.90)were presented as temperature 700-850℃,reduction time more than 3 hours,hydrogen flow rate 3m^3/h,dew point of hydrogen lower than-40℃,thickness of blue tungsten oxide smaller than 30mm.The conclusions drawn in this paper were valuable in understanding the procedure of reduction of blue tungsten oxide and determining the new process for production of ultrafine tungsten powder.