稀土元素钇对纳米级W-Ni-Fe复合粉末制备的影响

Effect of Rare Earth Y on Preparation of Nanometer W-Ni-Fe Composite Powder

以喷雾干燥法制备的(W,Ni,Fe)复合氧化物粉末为原料,采用700℃,保温90 min的条件进行还原;研究了不同稀土Y含量对还原制备纳米级W-Ni-Fe复合粉末性能的影响;采用XRD及高倍SEM分别对所制备的复合粉末进行了物相分析、晶粒尺寸测试和形貌观察;并对所制得复合粉末的Fsss粒度、比表面进行了测定与分析.结果表明:不加稀土Y时还原粉末由W和y-(Ni,Fe)两相组成,添加一定量稀土Y的还原粉末有W,y-(Ni,Fe)和Y(Ni0.75W0.25)O3三相组成;当Y的质量分数在0%～0.8%范围内(占90W-7Ni-3Fe复合粉末的质量分数),随着Y含量的增高,粉末dBET粒度由96.6 nm降到45.2 nm,粉末Fsss粒度由0.64 μm降到0.28μm,粉末晶粒尺寸由26.1 nm降到19.8 nm;未添加稀土Y时粉末颗粒为球形,添加一定量的稀土Y,粉末颗粒变为近球形或多面体;添加一定量的稀土Y不仅可以有效地抑制晶粒的长大,还可以在一定程度上提高粉末的分散性.

(W, Ni, Fe) composite oxide powder synthesized by spray drying was used as starting materials and reduced at 700 degrees C for 90 minutes in H(2) atmosphere. The effect of rare earth element Y content on the characteristic of the composite powder was studied. The phase composition, the crystal size and the particle morphology of the composite powder were measured by X-ray diffraction and SEM. Fsss particle size and special surface area of the reduced powder were also measured and analyzed. The results show that the phase composition of the composite powder reduced are W and gamma-(Ni, Fe) upon adding no rare earth Y, but the phase composition of the composite powder reduced are W, gamma-(Ni, Fe) and Y(Ni(0.75)W(0.25))O(3) upon adding Y. When the Y content is under 0.8%, with the increasing of the Y content, d(BET) of powder decreases from 96.6 nm to 45.2 nm, Fsss of powder decreases from 0.64 mu m to 0.28 mu m, and the crystal size of the powder decreases from 26.1 nm to 19.8 nm. The particle morphology is spherical for adding no rare earth Y, but the particle morphology is nearly spherical or polyhedron for adding Y. Adding of Y not only inhibits the grain growth during reduction but also enhances the dispersion of the composite powder.