超细(W,Ni,Fe,Y)复合粉末制备过程中稀土Y的物相形态变化

Phase transformation of Y in fabricating ultra-fine (W, Ni, Fe, Y) composite powders

采用溶胶-喷雾干燥-氢还原法制备稀土Y含量分别为0,0.4%,5%,10%和20%的超细(W,Ni,Fe,Y)复合粉末,采用XRD研究煅烧温度和还原温度以及稀土Y含量变化时复合粉末体在制备过程中的相结构变化规律。结果表明:喷雾干燥前驱体随煅烧温度的升高渐渐从非晶体向复合氧化物晶化转变,添加稀土Y的粉末前驱体经煅烧后,Y与W形成复合氧化物Y2W3O12,且稀土Y可以有效地抑制粉末颗粒长大;随着Y含量的增加,Y和W的复合氧化物明显增加,Y2W3O12在700℃才能被还原成低氧复合氧化物相;含5%稀土Y粉末中的Y2W3O12被还原生成新相Y2WO6;当稀土Y增加到10%以上时,不仅生成Y2WO6,还生成另一种新相Y6W2O15。

Ultra-fine （W, Ni, Fe, Y） composite powders containing rare earth element Y of 0, 0.4%, 5%, 10% and 20%, respectively were fabricated by sol-spray drying calcination and subsequent hydrogen reduction process. X-ray diffractrometry（XRD） was used to analyze the phase transformation of composite powders during calcination and hydrogen reduction. The results show that the amorphous spray-dried precursors transform into composite-oxide powders, composite oxide phase of Y and W forms as Y2W3O12, and the addition Y can control the grain growth effectively. With the increase of Y contents composite oxide increase obviously. When temperature is 700 ℃, the Y2W3O12 phase is reduced into low-oxygen composite-oxide. A new phase Y2WO6 forms with addition of 5%Y, and when the amount of additions increase up to 10%, the new phases Y2WO6 and Y6W2O15 are formed.