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以四钼酸铵和硝酸铝为原材料,采用水热合成法结合低温煅烧和两次还原工艺制备出Al2O3掺杂钼粉,经压制、烧结后制备出掺杂钼坯。利用XRD、SEM、EDS、TEM等检测手段对不同制备阶段下的相结构、形貌及相转变进行了分析。结果表明:在水热合成过程中,有六方结构的针状MoO3和棉花状的水合氧化铝AlO(OH)生成,六方结构的MoO3是由四钼酸铵(NH4)2Mo4O13·2H2O与硝酸HNO3发生化学反应生成,水合氧化铝AlO(OH)是由硝酸铝Al(NO3)3·9H2O和尿素CO(NH2)2反应生成;500℃低温煅烧后,六方结构的针状MoO3转变为正交结构且呈片状,棉花状的水合氧化铝AlO(OH)脱水转变为Al2O3,且有中间相Al2(MoO4)3的生成;经二次氢气还原,片状的MoO3完全被还原为球状的Mo颗粒,含铝相以纳米级α-Al2O3相的形式存在于Mo粉中;烧结成坯后,α-Al2O3弥散分布在钼基体中,尺寸在500nm~1μm之间。
Ammonium molybdate and aluminum nitrate were used as raw materials to prepare Al2O3-doped molybdenum powder by hydrothermal synthesis combined with low-temperature calcination and double-reduction process. The molybdenum-doped molybdenum powder was prepared by pressing and sintering. The phase structure, morphology and phase transition under different preparation stages were analyzed by XRD, SEM, EDS and TEM. The results show that acicular hexagonal MoO3 and cotton-like hydrated alumina AlO (OH) are formed during the hydrothermal synthesis. The hexagonal MoO3 is formed by the reaction of ammonium tetrakisammonium (NH4) 2Mo4O13.2H2O and nitric acid HNO3 Chemical reaction, hydrated alumina AlO (OH) is formed by the reaction of aluminum nitrate Al (NO3) 3 · 9H2O and urea CO (NH2) 2; after calcination at 500 ℃, the acicular MoO3 with hexagonal structure turns into an orthorhombic structure The hydrated alumina AlO (OH) in the form of flake and cotton is dehydrated and transformed into Al2O3, and the formation of mesophase Al2 (MoO4) 3 is formed. After the secondary hydrogen reduction, the sheet-like MoO3 is completely reduced to the spherical Mo particles, The aluminum-containing phase is present in the Mo powder in the form of nano-sized α-Al2O3 phase. After sintering into a billet, the α-Al2O3 is dispersed and distributed in the molybdenum matrix and has a size of 500 nm to 1 μm.