碳纳米管对钢的影响及其在钢液中的结构变化

发布时间：2018-05-19 01:30

  本文选题：碳纳米管 + 铸造　； 参考：《南昌大学》2015年博士论文

【摘要】：碳纳米管以优异的物理化学性能在增强金属基复合材料方面具有优势,但如何将轻质碳纳米管添加进钢基体中一直是碳纳米管复合材料领域的难点。本文探索了三种把碳纳米管添加到钢基体中的方法,最终确定使用铸造冲入法将碳纳米管植入钢基体中,制备了钢基碳纳米管复合材料,研究了碳纳米管对钢的影响。对制备过程中涉及到的碳纳米管分散,碳纳米管与基体的结合,进行了研究与分析,运用扫描电镜,透射电镜以及拉伸试验,金相分析等分析测试手段观察分析了复合材料的组织结构,测试了复合材料的力学性能,对微观组织结构影响宏观力学性能进行了初步探讨。首次发现碳纳米管在浇注过程中形成了快速石墨化现象,对所发现笔直的石墨化碳纳米管进行了观察和研究。先将碳纳米管与铝粉混合球磨,得到混合物后将其置于压力机下制成饼状预制块,然后将这样的预制块粉碎并过筛得到粒度为2 mm的均匀颗粒,将此预制块颗粒撒放在浇包底部,倒入1550℃钢液,混合5s后浇入铸型内得到复合材料。对复合材料的力学性能进行测试,发现碳纳米管有助于提高复合材料的拉伸性能、硬度、摩擦磨损性能,其最优加入量为：对于拉伸性能,加入量以0.04%最优；对于硬度,加入量以0.01%最优；对于摩擦系数,加入量以0.04%最优；对于磨损量,加入量以0.1%最优。对复合材料的金相分析结果表明：碳纳米管的添加对基体有着较为明显的晶粒细化作用：随着碳纳米管加入量的增加,晶粒度水平有提高,在碳纳米管加入量为0.1%时候效果最好,其后随着碳纳米管加入量增加,晶粒度水平降低；碳纳米管的添加对晶粒度的影响是有方向性的。随着碳纳米管加入量的增加,基体在其中一个方向的晶粒度越来越高,在另一个方向上的影响不明显。使用场发射扫描电镜和高分辨透射电镜对样品进行形貌分析。发现碳纳米管与钢形成“钢筋混凝土式”加强结构,照片显示钢液能够包裹碳纳米管,从而形成加强结构,承担外来载荷,使得复合材料的力学性能得以提高。发现笔直碳纳米管。高分辨透射电镜结果显示笔直碳纳米管管壁高度平行排列,这显示碳纳米管在浇注时在钢液的催化作用下形成了快速而完全的石墨化。而这样的笔直碳纳米管使碳纳米管分散问题得到完全解决成为可能。首次发现能在1550℃以下数十秒内使碳纳米管达到几乎完全石墨化的程度。管壁高度平行排列显示原始碳纳米管内部的缺陷被大量消除。以往的认识认为超过2200℃时石墨化较完全,且在2.5大气压下需要15mins,而在1800℃以下不能发生石墨化。相比以往的科学发现,本实验的发现无论是在石墨化温度以及石墨化速度都是一个科学突破。
[Abstract]:Carbon nanotubes (CNTs) have advantages in strengthening metal matrix composites with excellent physical and chemical properties, but how to add light carbon nanotubes into steel matrix has always been a difficult point in the field of carbon nanotubes composites. In this paper, three methods of adding carbon nanotubes (CNTs) to steel substrates were explored, and the effect of carbon nanotubes (CNTs) on steel was studied. The dispersion of carbon nanotubes and the bonding of carbon nanotubes with matrix were studied and analyzed. Scanning electron microscope, transmission electron microscope and tensile test were used. The microstructure and mechanical properties of the composites were observed and analyzed by means of metallographic analysis. The influence of microstructure on the macroscopic mechanical properties was preliminarily discussed. The rapid graphitization of carbon nanotubes (CNTs) was first found during the pouring process. The straight graphitized CNTs were observed and studied. The carbon nanotubes were milled with aluminum powder, and then the mixture was placed under the press to make the cake shape preform, and then the prefabricated blocks were crushed and sifted to obtain the uniform particle size of 2 mm. The prefabricated particles were sprayed at the bottom of the ladle and poured into the molten steel at 1550 鈩，

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