用熔盐电解法制备超细钨粉

PREPARATION OF ULTRAFINE TUNGSTEN POWDER BY ELECTROLYZING IN MOLTEN SALTS

在ＮａＣｌ－ＫＣｌ－Ｎａ２ＷＯ４－ＷＯ３熔体中，用熔盐电解法电解氧化钨制取细钨粉和超细钨粉．在电解温度为７２０℃，阴极电流密度为 ２５０ｍＡ／ｃｍ～２的条件下，得到平均等积圆直径为１．２μｍ、长宽比为１．６的超细钨粉．在低阴极电流密度时，阴极的电解反应为Ｗ～（６＋）放电，在高阴极电流密度时，阴极的电解反应为Ｎａ＋放电．研究了温度、阴极电流密度和Ｎａ２ＷＯ４的含量对电流效率的影响．

Under the condition of electrolysis temperature 720 ℃ and catholic current density 250mA/cm^2, the tungsten powders particle of average eqivalance circle diameter 1.2μm can be obtained. The powders were verified by X-ray phase analysis, and the ratio of length size to width size is 1.6. Measurement results for opposing electromotive force of electrolysis reaction showed that W6+ directly discharged and became W at lower cathodic current density, the cathode reaction occurred in two steps at higher cathode current density: first Na+ discharged and became Na, then W6+ was reduced by Na to W. The effects of temperature, cathodic current density and the concentration of Na2WO4 in the molten salt on the current efficiency have been investigated. The results showed that the current efficiency is decreased with increase of temperature,the current efficiency is increased with increase of concentration of Na2WO4 and the maximum of current efficiency can be obtained when the cathode current density is 150mA/cm^2.