【作者】 孙维民；

【导师】 刘正；

【作者基本信息】 沈阳工业大学 ， 材料加工工程， 2008， 博士

【摘要】 本文以直流电弧等离子体法制备金属纳米粉、金属-陶瓷复合纳米粉的工业化技术和金属纳米粉应用为目的,对纳米粉的稳定化处理方法、抗氧化性能及应用进行了研究。采用直流电弧等离子体制备了松油醇(C₁₀H₁₈O)包覆Cu-Ag复合纳米粉,C包覆Ni、Fe纳米粉,Mg纳米粉、Mg-Mg₂Si-Si复合纳米粉和Fe-TiC复合纳米粉。利用X射线衍射（XRD）、透射电子显微镜（TEM）、X光电子谱（XPS）、红外光谱（IR）、化学分析、氧含量分析、示差热-热重（DSC-TG）和振动样品磁强计（VSM）等测试技术,研究了纳米粉的相组成、形貌、结构、抗氧化性能和磁性等。用松油醇包覆的Cu-Ag复合纳米粉作为导电相制备了导电浆料,研究了其制备方法和导电性能;用C包覆的Ni、Fe纳米粉作为磁性颗粒制备了耐腐蚀、高粘度磁性液体,研究了其制备方法和耐腐蚀性能。针对金属纳米粉用于制备导电浆料时,其表面的氧化层严重影响导电性能,开发了一种用直流电弧等离子体制备金属纳米粉的稳定化方法,即气-液两相稳定法。并用该方法制备了松油醇包覆的Cu-Ag复合纳米粉,制得的复合纳米粉具有双层的壳结构,内层是一层薄的氧化层,外层是松油醇分子层。具有双层壳结构的Cu-Ag复合纳米粉比单氧化层结构的粉体的抗氧化性和导电性好。针对用直流电弧等离子体在纯CH₄气氛下制备的C包覆Ni、Fe纳米粉中含有大量的游离碳,严重降低其饱和磁化强度的问题,研究了将工作气氛改变为50%CH₄+20%H₂+30%Ar的混合气氛的稳定化方法。制备出的C包覆Ni、Fe纳米粉中的游离碳含量分别降低了11wt%和12wt%,饱和磁化强度分别提高了5.1A·m²/kg和45.5A·m²/kg。针对Mg纳米粉具有极高的表面活性、易氧化、易燃、易爆和不易批量制备的问题,研究了用直流电弧等离子体批量制备Mg纳米粉的工艺、粉体的稳定化处理方法和抗氧化性。结果表明,在Ar、Ar+H₂和Ar+CH₄三种不同工作气氛下制备的Mg纳米粉,在含有微量氧气和空气的氩气中稳定化处理后可得到稳定的Mg纳米粉,其中在Ar+CH₄气氛下制备的Mg纳米粉的稳定性和抗氧化性最好。针对机械合金化法制备Mg基复合纳米粉费时、能耗大的问题,研究了用直流电弧等离子体以纯Mg为原料,在含有SiH₄的气氛中合成Mg-Mg₂Si-Si复合纳米粉的工艺、稳定化处理方法和抗氧化性。结果表明,用含有微量氧气和空气的氩气稳定化处理后可得到稳定的Mg-Mg₂Si-Si复合纳米粉。在室温大气条件下,粉体中Mg₂Si相的含量越高,则抗氧化性越好。在流动空气中,粉体温度高于410℃左右时,粉体氧化速度加快。针对球磨法制备TiC弥散强化铁基合金粉末时间长、能耗大的问题,研究了用直流电弧等离子体以Fe-Ti合金为原料,在含有CH₄的气氛中合成Fe-TiC复合纳米粉的工艺、稳定化处理方法和抗氧化性。结果表明,用含有微量氧气和空气的氩气稳定化处理后可得到稳定的Fe-TiC复合纳米粉。粉体由Fe、TiC和少量Fe₃C组成,复合粒子的形态主要有亚铃形和多面体形,复合粒子的生成机制遵寻VLS机制。并对气相中可能发生的化学反应进行了热力学计算。在室温大气条件下,粉体中TiC相的含量越高则抗氧化性越好。在流动空气中,温度高于330℃时样品氧化明显加快,在410℃左右,TiC纳米粒子氧化分解。针对目前贵金属价格猛增,使得电子浆料的成本不断提高这一问题,初步进行了纳米低成本金属电子浆料的制备研究。用松油醇包覆的Cu-Ag复合纳米粉作为导电相、用乙基纤维素为添加剂的松油醇溶剂为载体,配制了导电浆料,该导电浆料在烧结温度180℃-200℃、保温时间60min-70min、真空度为1.33Pa条件下获得了电阻率为（1.10-2.16）×10^-4Ω·cm的导电膜。针对目前国内无耐腐蚀、高粘度磁性液体这一问题,初步进行了耐腐蚀、高粘度磁性液体的制备研究。用C包覆的Ni、Fe纳米粉作为磁性颗粒、油酸为表面活性剂、全氟聚醚油和少量硅脂的混合液为基液制备了耐腐蚀、高粘度磁性液体。制备的磁性液体具有较好的耐腐蚀性能。磁性液体在25℃粘度为9Pa·S-25Pa·S,在85℃粘度为2Pa·S-16Pa·S,室温下饱和磁化强度为Ni磁性液体5.19A·m²/kg-17.83A·m²/kg、Fe磁性液体15.36A·m²/kg-59.88A·m²/kg。更多还原

【Abstract】 With a research background of industrial production and application of metal nanopowders, metal-ceramics composite nanopowders fabricated by arc discharge method,the stabilization, oxidation resistance and application of the nanopowders are studied in this thesis.A series of objective materials encapsulated nanopowders are prepared by arc discharge. The phase composition,core-shell structure and morphology are characterized by X-ray diffraction（XRD） and transmission electron microscope（TEM）.X-ray photoelectron spectroscopy（XPS）,infrared spectrum（IR）,oxygen content analysis and differential thermal-thermogravimetry analysis（DSC-TG） are used to analysis the surface layer,oxidation resistance.Magnetic behavior is investigated by using vibrating sample magnetometer（VSM）. The conductive paste is prepared by using Cu-Ag composite nanopowders coated with terpineol (C₁₀H₁₈O) as conductive phase,the fabrication technology and conductive characters are also discussed.The magnetic liquid of the corrosion resistance and high viscosity is prepared using Ni,Fe nanopowders covered by carbon as magnetic-particles,the preparation technology and corrosion resistance are researched.A new stabilization method,called gas-liquid phase stability method for metal nanopowders by arc discharge is applied.The new method is mainly to solve the problem that the oxide layer of the nanopowders surface has a strong impact on conductibility during the preparing conduct paste by the metal nanaopowder.Cu-Ag composite nanopowders coated with terpineol are prepared by the new method.It turn out these nanopowders have double-shells structure,a thinner oxide layer is encapsulated by terpineol molecular layer.These nanopowders with double-shells structure show better oxidation resistance and conductibility comparing with single oxide layer structure.To aim at the problem that a lower saturation magnetization is always obtained under pure CH₄ atmosphere by arc discharge.A great of free carbons in nanopowders play the most important role.We try to change the working atmosphere with 50%CH₄+20%H₂+30%Ar mixture atmosphere.The experiment shows 11wt%and 12wt%of free carbon content is decreased,saturation magnetization increased 5.1A·m²/kg and 45.5A·m²/kg for Ni and Fe nanopowders.The Mg nanopowders have ultra high surface activity,easy oxidation,flammability,easy burst and difficultly to be prepared in large quantity.A systematic preparation and stabilization technology to avoid these problems by arc discharge is researched in this thesis.The experiment results that the Mg nanopowders prepared in Ar,Ar+H₂ and Ar+CH₄ can be stabilized in Ar with little O₂ and air.The Mg nanopowders prepared in Ar +CH₄ atmosphere have the best stability and oxidation resistance.The energy exhaust and time consuming during preparing Mg based composite nanopowders by the mechanism alloying method are to be solved problem.A technology which Mg-Mg₂Si-Si composite nanopowders are synthesized by arc discharge is developed.Pure Mg takes as a raw material and is prepared under the mixture with SiH₄ atmosphere.The results show that the Mg-Mg₂Si-Si composite nanopowders can be stabilized in Ar with little O₂ and air.At room temperature and under atmospheric conditions,the more Mg₂Si phases in powder, the better oxidation resistance.In flow air condition,the powders are evidently oxidized when temperature is higher than 410℃.There exist many problems to prepare TiC dispersion strengthening iron base nanopowders by the ball milling method such as energy exhaust and time consuming etc.Fe-TiC composite nanopowders are synthesized under different condition by arc discharge.Fe-Ti alloy is taken as a raw material,and is prepared the Fe-TiC composite nanopowders in mixture with CH₄ atmosphere.The results show that the Fe-TiC composite nanopowders can be stabilized in Ar with little O₂ and air.The composite nanopowders consist of Fe,TiC and little Fe₃C.The morphology of composite nanoparticles owns two types.One is dumbell-like,another is polyhedron.The growth mechanism of composite nanoparticles obeys VLS.Thermodynamic calculation of chemical reaction in gas phases has been done to analyze the possibility of reactions.At room temperature and under atmospheric conditions,the more TiC phases in powder,the better oxidation resistance.In flow air condition,the powders are evidently oxidized when temperature is higher than 330℃.TiC nanoparticles are oxidized to dissolve at about 410℃.To aim at the problem that the cost of the conduct paste increase with the price of the precious metal,the preparation of the conduct paste for nanopowders of inexpensive metal is studied preliminarily.The conduct paste is synthesized by Cu-Ag composite nanopowders coated with terpineol as conduct phase and terpineol solvent additive ethylcellulose as bearer.A thick film with resistivity（1.10-2.16）×10^-4Ω·cm can be obtained after the nanopowders conductive paste sintered at 180℃-200℃for 60 min-70 min under 1.33Pa.At present,there is no magnetic liquid with corrosion-resistant and high viscosity in our country.The preparation of magnetic liquid with corrosion resistant and high viscosity is studied preliminarily.Ni and Fe nanometer particle coated with carbon are to be magnetic particle,oleic acid as surfactant,miscible liquids of polyether oil and little silicone grease as base solution.The prepared magnetic liquid shows high resistant corrosion ability.The viscosity of magnetic liquid is 9Pa·S -25Pa·S at 25℃and 2Pa·S -16Pa·S at 85℃.The saturation magnetization of Ni magnetic liquid is 5.19A·m²/kg-17.83A·m²/kg and Fe magnetic liquid is 15.36A·m²/kg-59.88A·m2Z/kg.更多还原