Molecular Simulations for Development of CarbonNanoparticle - Metal Nanocomposites

由于其强大的共价键，碳纳米颗粒是最坚固的材料之一。如果这种纳米粒子能被牢牢地嵌入像铝这样的轻质材料中，强度就会有很大的提高。为了获得凝固后均匀的复合材料结构，需要在铝熔体中均匀分布纳米颗粒。然而，有两个重要的因素阻碍了这种简单的加工策略：第一，碳纳米颗粒没有被液态铝润湿，它们在固体铝中的界面结合可能很弱；第二，这些颗粒在浸入熔体或溶液中时有很强的团聚倾向。缓解这一问题的一个策略是修改纳米粒子的表面，通过在其表面涂上镍或铂等与碳结合更强的金属，或者用相同金属的纳米级原子簇来装饰它。这种表面改性可以增加碳纳米颗粒在液态铝中的润湿性，降低其团聚倾向，同时涂层或装饰金属可以起到“纳米胶”的作用，将碳纳米颗粒牢固地固定在凝固的铝中。在我们的项目中，我们通过进行分子动力学模拟来研究金属修饰或涂层的碳纳米颗粒在分离状态下以及在液态和固态铝中的性能。我们的目标是找出什么样的表面改性参数可以很好地分离铝熔体中的碳纳米颗粒，同时将它们牢固地结合到固体复合材料中。此外，我们希望了解嵌入纳米颗粒如何改变所得到的纳米复合材料的变形和断裂性能，并确定增强力学性能的最佳参数。这项研究将与英国和中国的同事合作进行，他们通过实验和其他模拟方法（如密度泛函理论）研究相同的金属-碳系统。

Because of their strong covalent bonds , carbon nanoparticles are among the strongest of materials. If such nanoparticles can be firmly embedded into lightweight materials such as Aluminum, one can expect very significant gains in strength. It would be desirable to distribute the nanoparticles homogeneously in Aluminum melt, in order to obtain after solidification a homogeneous composite structure. Howerer, there are two important factors which hinder such a simple processing strategy: First, carbon nanoparticles are not wetted by liquid Aluminum and their interfacial bonding in solid Aluminum is likely to be weak, second, these particles have a strong tendency to agglomerate when immersed in melts or solutions. A strategy for mitigating this problem consists in modifying the nanoparticle surface, by coating it with metals like Nickel or Platinum which bond more strongly to carbon, or to decorate it with nanoscale atomic clusters of the same metals. Such surface modification might increase the wettability of the carbon nanoparticles by liquid Aluminum and reduce their agglomeration tendency, and at the same time the coating or decorating metals might act as a um'nano-glue' that firmly anchors the carbon nanoparticles in the solidified Aluminum.In our project we pursue this idea by conducting molecular dynamics simulations to study the properties of metal decorated or coated carbon nanoparticles both in isolation and in liquid and solid Aluminum. It is our aim to find out what surface modification parameters yield good results in separating carbon nanoparticles in the aluminum melt while firmly bonding them into the solid composite. In addition we want to find out how embedded nanoparticles change the deformation and fracture properties of the resulting nanocomposites and identify optimal parameters for mechanical property enhancement. The research will be conducted in collaboration with colleagues in the UK and in China who investigate the same metal-carbon systems experimentally and with other simulation methods such as density functional theory.