Effect of rare earth element cerium on preparation of tungsten powders

Tungsten powders and Ce doped powders were prepared by hydrogen reduction combined with the liquid-solid doping method. The phase composition, particle size and powder morphology of Ce doped tungsten powders were analyzed by X-ray diffraction, scanning electron microscopy and transmission electron microscopy, respectively. The results indicated that 10000 ppm Ce doped tungsten oxide powders were consisted of WO3 phase and Ce4W9O33 phase. The hydrogen reduction of Ce doped tungsten powders was basically accomplished at 800 degrees C for 3 h. The size of Ce doped W powders was remarkably decreased compared to the undoped W powders. The phase of Ce4W9O33 was reduced to Ce-2 (WO4)(3) phase and Ce2W2O9 phase during the process of hydrogen reduction. Moreover, Ce-2 (WO4)(3) phase and Ce2W2O9 phase were observed form their morphologies, where the doping content of Ce was more than 100 ppm. The ternary phase embedding into W particles was assigned to Ce-2 (WO4)(3), while the ternary phase distributing among W particles corresponded to Ce2W2O9. The phase of Ce-2 (WO4)(3) might be the nucleus of W particles and increase the number of the nucleus. And the particles of Ce2W2O9 covered WO2 particles and might inhibit the growth of W particles. These two reasons resulted in the decrease of the size of Ce doped W particles. Uniform fine W powders were fabricated with the doping content of Ce more than 100 ppm.