多壁碳纳米管增强镁基复合材料制备及界面研究

发布时间：2018-02-03 16:02

本文关键词： 碳纳米管混杂增强镁基复合材料预分散界面调控　出处：《哈尔滨工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：本文研究了碳纳米管(CNTs)机械球磨的预分散工艺,并对CNTs/Mg-6Zn复合材料的机械搅拌复合高能超声波制备工艺进行了探索。成功制备出增强体体积分数不同的CNTs/Mg-6Zn和CNTs+Si C/Mg-6Zn复合材料,并对制备的铸态复合材料进行热挤压变形制备出挤压态的复合材料。采用多种分析手段对复合材料的显微组织进行了研究,并对铸态和挤压态复合材料室温拉伸性能进行了测试,分析了显微组织和力学性能的关系。通过加入Al元素调控碳纳米管与镁基体的界面结合。预分散工艺研究表明,将锌粉和碳纳米管混合机械球磨能够打散原始碳纳米管的团聚,改善碳纳米管的分散情况。球磨转速及时间对碳纳米管的分散都有一定的影响。当球磨转速为400rpm,球磨时间为4h时,取得了最佳的碳纳米管分散效果。将锌粉、碳纳米管和纳米碳化硅颗粒混合球磨能同时分散纳米碳化硅颗粒和碳纳米管,有利于增强体进一步在复合材料中的分布。探索出一种新型的制备碳纳米管增强镁基复合材料的液态制备法。首先将碳纳米管和锌粉进行混合球磨对碳纳米管进行预分散。然后在半固态对基体合金进行机械搅拌并加入增强体。之后在液态对复合材料进行高能超声处理。通过这三步逐渐的分散碳纳米管制备出碳纳米管在基体中分布弥散的铸态镁基复合材料。通过这种方法制备了质量分数分别为0.5%和1.0%的CNT/Mg-6Zn复合材料。碳纳米管在基体中分布均匀,未见明显的团聚产生。碳纳米管依然保持着其结构完整性,经过球磨、机械搅拌和高能处理后,通过透射观察发现其管壁结构依然非常完整。利用这种三步分散的液态制备法我们制备了新型的纳米碳化硅颗粒混杂碳纳米管增强Mg-6Zn复合材料。在球磨过程中,碳纳米管与碳化硅颗粒互相起到分散对方的作用。碳化硅颗粒的加入改变了基体合金中第二相的固溶度,析出了大量与镁基体有特殊位相关系的棒状第二相。当碳化硅体积分数为1.0%,碳纳米管体积分数为0.5%时复合材料的屈服强度和拉伸强度达到最高,分别为242MPa和318MPa。热挤压变形显著细化了基体合金的晶粒,但是晶粒尺寸分布非常不均匀。热挤压改善了碳纳米管的分布,使得碳纳管沿挤压带定向分布。在碳纳米管的条带中,晶粒尺寸非常细小表明碳纳米管能够组在再结晶晶粒的长大。热挤压显著提高合金和复合材料的力学性能。碳纳米管的加入显著细化了基体合金的晶粒,提高了挤压态复合材料的强度,碳纳米管的拔出和桥连增强作用提高了复合材料的额韧性。Al元素的加入旨在与复合材料中的碳纳米管表面的无定向碳发生化学反应在其界面处生成界面产物来改善复合材料与增强体之间的界面结合。通过透射观察发现其界面处确实产生了一些细小的第二相。与此同时,Al元素的加入改变了复合材料中第二相的固溶度,减少了其中第二相的析出。由于基体合金成分改变,碳纳米管与基体润湿性得到改善,间接地提高了碳纳米管与基体合金的界面结合,使复合材料的力学性能得到了显著地的提高。
[Abstract]:This paper studies the carbon nanotube (CNTs) dispersion process of mechanical milling of CNTs/Mg-6Zn composites and pre mixing composite ultrasonic preparation technology was explored. Successfully prepared the volume fraction of different CNTs/Mg-6Zn and CNTs+Si C/Mg-6Zn composites, and the cast composites were prepared by composite the material extruded hot extrusion. By using kinds of analysis methods on the microstructure of the composite were studied, and the tensile properties of the cast and extruded state of composite material were tested, analyzed the relationship between the microstructure and mechanical properties. By combining the elements of Al regulation of carbon nanotubes with magnesium matrix pre dispersed interface. Experiments show that the new technology of zinc and carbon nanotube hybrid mechanical milling can break up original carbon nanotube agglomeration, improve dispersion of carbon nanotubes and the milling speed. Dispersion of carbon nanotubes have a certain impact. When the milling speed is 400rpm, ball milling time is 4h, the best dispersion of carbon nanotubes. The zinc powder, carbon nanotubes and nano SiC particles can be dispersed and mixed milling nano SiC particles and carbon nanotubes, is conducive to further enhance body distribution in composite materials. To explore a new preparation method of carbon nanotube reinforced liquid preparation of magnesium matrix composites. Firstly, carbon nanotubes and zinc powder mixing ball milling pretreatment on the dispersion of carbon nanotubes. Then in the semi solid state of matrix alloy mechanical stirring and adding reinforcement. After the high-energy ultrasonic treatment on the composite material in liquid through this three step gradually dispersed carbon nanotubes prepared by as cast magnesium matrix composite dispersed carbon nanotubes in the matrix prepared by this method. The mass fraction Don't CNT/Mg-6Zn composites with 0.5% and 1%. Carbon nanotubes uniformly distributed in the matrix, and there is no obvious agglomeration. Carbon nanotubes still maintains its structural integrity, after ball milling, mechanical agitation and high-energy treatment, observed by transmission structure of the tube wall is still very complete. By using the three step dispersion liquid the preparation method for our new nano SiC particles reinforced Mg-6Zn composite hybrid carbon nanotubes were synthesized. In the process of ball milling, carbon nanotubes and silicon carbide particles to disperse each other each other. The effect of SiC particles could change the solubility of the second phase of the matrix alloy, precipitated a lot with the magnesium matrix with special phase relationship between the rod of the second phase. When the SiC volume fraction is 1%, the volume fraction of the carbon nanotubes is 0.5% composite material yield strength and tensile strength reached the maximum, respectively 242MPa and 318M Pa. hot extrusion significantly refined grains of the matrix alloy, but the grain size distribution is very uneven. The hot extrusion can improve the distribution of carbon nanotubes, the carbon nano tube along the extrusion zone. Directional distribution in strip of carbon nanotubes, the grain size is very small that can grow up in the group of recrystallized grains of carbon nanotubes. Hot extrusion significantly improve the alloy and the mechanical properties of composite materials. The addition of carbon nanotubes significantly refines the grains of the matrix alloy, improve the strength of extruded composites, carbon nanotube pull-out and bridging enhancement effect to improve the toughness of.Al composite material, the elements added to the surface of carbon nanotubes in composite materials the non directional carbon chemical reaction on the interface generation interface products to improve the composite material and the interfacial bonding between the reinforcement. The interface was observed by transmission did produce The second phase of some small. At the same time, the addition of Al changed the solid solubility of the second phase in the composite, which reduces the second phase precipitation. The matrix alloy due to changes in composition, carbon nanotube and matrix wettability improved, indirectly increasing carbon nanotube and matrix alloy interface, the mechanical properties of composite the material has been significantly improved.

【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB33;TQ127.11

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