钨酸铵溶液浓度对超微钨粉形貌的影响

Effect of Tungsten Content of Ammonium Tungstate Solution on the Particle Shape of Nanometer Tungsten Powder

以钨酸铵溶液为原料,采用超声喷雾干燥法制备了超微钨粉。研究了该方法中钨酸铵浓度对超微钨粉形貌的影响。结果表明,当溶液中钨酸铵的浓度为10%时,得到了球形度很好的非完全结晶的前驱体。当钨酸铵浓度达25%时,得到了层片状的晶态前驱体。钨酸铵溶液浓度对干燥时晶体生长速度具有重要的影响。分别采用这2种前驱体在630°C,保温30min和氢气流量4L/min条件下能够完全还原,得到超微!-W粉。所制得的钨粉形貌完全遗传了其前驱体的形貌,分别得到球状和层状钨粉。球状钨粉由纳米颗粒聚集而成。片层状钨粉的厚度在1mm以下。

Nanometer tungsten powder has attracted more attention in product of tungsten. The particle shape of nanometer powders have very important influence on later pressing and sintering. By ultrasonic spraying and drying process, nanometer tungsten powder is made from ammonia tungstate, This paper studied the influence of precursor solution concentration on ultrasonic spraying and drying. The results show that： spherical and amorphous precursor powder can be obtained when tungsten content of ammonia tungstate solution is 10wt%; flaky and crystal precursor powder can be obtained when tungsten content of ammonia tungstate solution is 25wt%. The growth speed of crystal is influenced strongly by the concentration of ammonia tungstate. These two precursor powder can be reduced by hydrogen completely at 380℃×30 min, 630℃×60 min, and the flow rate of hydrogen is 4 L/min. The morphology of tungsten powder inherit that of its precursor powder.