摘要
Al_(2)O_(3)协同La_(2)O_(3)强韧化的钼及钼合金具有优越的综合力学性能,通过粉末冶金方法制备钼及钼合金的关键在于获得超细或纳米Mo-Al_(2)O_(3)-La_(2)O_(3)粉末。本文以仲钼酸铵、硝酸铝、硝酸镧和柠檬酸为原料,采用溶胶-凝胶-煅烧-高温氢还原工艺制备Mo-Al_(2)O_(3)-La_(2)O_(3)复合粉末,利用XRD、SEM、EDS和TEM等分析手段对粉末的微观组织结构进行表征。结果表明:当水浴温度为85℃、pH=1、柠檬酸与钼酸铵的质量比为1.7时,形成了网状结构大分子交联的络合物前驱体,这有利于在后续高温还原过程中制备超细或纳米Mo复合粉末。前驱体粉体在550℃煅烧3 h后,粉末主要由MoO_(3)和Al_2(MoO_(4))_(3)组成。采用一步高温氢还原时,还原3 h后MoO_(3)全部转化成Mo,其最低还原温度为650℃。在650℃以下通过氢还原得到了微米尺寸Mo-Al_(2)O_(3)-La_(2)O_(3)复合粉末,而在750℃通过氢还原得到了由纳米颗粒聚集而成的近球形絮状粉末,在850℃通过氢还原得到的粉末内部出现烧结颈,其颗粒尺寸略有增大。
Mo and Mo alloys strengthened and toughened with Al_(2)O_(3)and La_(2)O_(3)are expected to exhibit excellent comprehensive mechanical properties.The key issue to prepare Mo and Mo alloys by powder metallurgy method is to obtain the ultrafine or nanometer Mo-Al_(2)O_(3)-La_(2)O_(3)powder.The composite powder was first prepared by sol-gel method using La(NO_(3))_(3)·6H_(2)O,(Al(NO_(3))_(3) and(NH_(4))_(6)Mo_(7)O_(2)_(4)·4H_(2)O)as raw materials,and followed by high temperature hydrogen reduction of the precursor.Phase composition and microstructure of the powder was investigated by X-ray diffraction(XRD),scanning electron microscope(SEM),energy dispersive spectroscopy(EDS)and transmission electron microscope(TEM).The results show that the precursor powder with interconnected network macromolecules can be prepared when the water bath temperature is 85℃,pH value is 1 and the mass ratio of citric acid to ammonium molybdate is 1.7,which is conducive to the formation of the ultrafine or nano-Mo composite powder in the subsequent reduction process.The powder is composed of MoO_(3) and Al_(2)(MoO_(4))_(3) after the precursor powder calcined at 550℃ for 3 h.The temperature must be over 650℃ by using a one-step reduction method when the MoO_(3) is completely reduced to Mo.The Mo-Al_(2)O_(3)-La_(2)O_(3)composite powder with micron size is obtained after hydrogen reduction below 650℃.The nanometer powder with spherical flocculent particles is prepared when the calcined powder is reduced at 750℃.However,the sintered neck structure is formed among the particles that is reduced at 850℃,and the size of the powder increases slightly.
作者
颜建辉
唐幸
汪异
邱敬文
王跃明
宋晨飞
YAN Jian-hui;TANG Xing;WANG Yi;QIU Jing-wen;WANG Yue-ming;SONG Chen-fei(College of Materials Science and Technology,Hunan University of Science and Technology,Xiangtan 411201,China;Hunan Provincial Key Defense Laboratory of High Temperature Wear Resisting Materials and Preparation Technology,Hunan University of Science and Technology,Xiangtan 411201,China;National United Engineering Laboratory for Advanced Bearing Tribology,Henan University of Science and Technology,Luoyang 471000,China)
出处
《中国有色金属学报》
EI
CAS
CSCD
北大核心
2023年第4期1096-1109,共14页
The Chinese Journal of Nonferrous Metals
基金
国家自然科学基金资助项目(52175167)
湖南省自然科学基金资助项目(2020JJ4025)
高端轴承摩擦学技术与应用国家地方联合工程实验室开放基金资助项目(202203)。
