动态碳热还原法制备纳米级钨粉

Preparation of Nano-tungsten Powder by Dynamic Carbothermal Reduction Method

摘要:

高品质纳米钨粉是制取高性能纳米晶钨合金和硬质合金的前提，氢还原制备钨粉因产生WO₂(OH)₂导致钨粉晶粒长大，碳热还原法可有效避免这一问题。本研究重点对碳热还原温度、气氛、时间以及动/静态工序对产物相结构和粒度等影响规律进行分析。结果表明：真空气氛下产物纯度高于氩气气氛；随还原温度升高，产物由高价氧化钨向低价氧化钨转变并最终转变为纯钨；保温时间为1 h时，随还原温度从1000 ℃升至1100 ℃，钨粉平均粒度由67 nm升至118 nm，还原温度为1000 ℃时，随保温时间从1 h延长至3 h，钨粉平均粒度从67 nm升至93 nm；在1000 ℃、保温1 h的真空动态碳热还原下，制备出平均粒径为67 nm的纳米钨粉。

Abstract:

High-quality nano-tungsten powder is the prerequisite for the preparation of high-performance nanocrystalline tungsten alloys and cemented carbides. The tungsten powder prepared by hydrogen reduction produces WO₂(OH)₂, which leads to the growth of tungsten powder grains. The carbothermal reduction method can effectively avoid this problem. This study focused on the influence of carbothermal reduction temperature, atmosphere, time and dynamic/static process on the phase structure and particle size of the product. The results show that the purity of the product in vacuum atmosphere is higher than that in argon atmosphere. With the increase of reduction temperature, the product changes from high-valence tungsten oxide to low-valence tungsten oxide and finally to pure tungsten. When the holding time is 1 h, the average particle size of tungsten powder increases from 67 nm to 118 nm with the increase in reduction temperature from 1000 ℃ to 1100 ℃. When the reduction temperature is 1000 ℃, the average particle size of tungsten powder increases from 67 nm to 93 nm with the prolongation of holding time from 1 h to 3 h. Nano-tungsten powder with an average particle size of 67 nm can be prepared under the vacuum dynamic carbothermal reduction at 1000 ℃ for 1 h.