Ni对纳米α-Al_2O_3/Ni粉体中α相转变温度的影响

Effect of Ni in α-Al_2O_3/Ni nanocomposite powders on the phase transformation temperature to alpha alumina pressing TiC/Ti/Al powder mixtures

以Al(NO3)3·9H2O和(NH4)2CO3溶液为原料,将实验室自制的纳米镍粉加入其中,利用非均相沉淀法制备出粒径<50nm的纳米α-Al2O3/Ni复合粉体,并用XRD、TEM等手段对纳米复合粉体进行了物相分析及形貌观察.讨论了复合粉体中镍对α-Al2O3相转变温度的影响.结果表明:纳米镍的存在可降低过渡型氧化铝向α型氧化铝转变的相变温度.

Al_2O_3/5%Ni and Al_2O_3/10%Ni nanocomposite powders with mean particles size less than 50nm were respectively prepared by the heterogeneous precipitation process using Al(NO_3)_3·9H_2O and (NH_4)_2CO_3 solutions and nickel nano-powders as raw materials. The phase analysis and the powder morphology were characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM) respectively. After Al(OH)_3/Ni dried gel calcined at 1000, 1100 and 1150℃ for an hour in vacuum, the Al_2O_3 powders combinated with 10%Ni transfer to α-Al_2O_3at 1150℃, while the Al_2O_3 powders without Ni and with 5vol%Ni remain γ-Al_2O_3 type in the same condition, that is the phase transformation temperature to alpha alumina drops by adding nanometer nickel powders. The nanocomposite powders are simply mechanically mixed together from the XRD patterns, because no new phases, which are different from Al_2O_3 and Ni, were observed.