Effect of Nanoparticle Size on the Mechanical Strength of Ni–Graphene Composites

Abstract

The effect of the size of nickel nanoparticles on the fabrication of a Ni–graphene composite by hydrostatic pressure at 0 K followed by annealing at 1000 and 2000 K is studied by molecular dynamics simulation. Crumpled graphene, consisting of crumpled graphene flakes interconnected by van der Waals forces is chosen as the matrix for the composite and filled with nickel nanoparticles composed of 21 and 47 atoms. It is found that the main factors that affect composite fabrication are nanoparticle size, the orientation of the structural units, and temperature of the fabrication process. The best stress–strain behavior is achieved for the Ni/graphene composite with Ni47 nanoparticle after annealing at 2000 K. However, all of the composites obtained had strength property anisotropy due to the inhomogeneous distribution of pores in the material volume.

Methodologyfor Molecular Dynamics Simulation of Plastic Deformation of a Nickel/Graphene Composite

“…The elongation of Ni/graphene composites during uniaxial tension proceeds due to the formation of long carbon chains. In [ 39 , 60 , 61 ], the long carbon chains were formed by breaking old carbon bonds and forming new ones. These carbon chains, under incremental uniaxial tension at ps , break fairly quickly at 0.84.…”

“…As it was shown for Ni/graphene composite, fabrication of the composite with a more homogeneous structure enhanced mechanical properties [ 22 ]. The strength properties of Ni/graphene composite strongly depend on the direction of the uniaxial tension under dynamic regime [ 39 ]. Thus, changes in the strength of the composite during incremental deformation along different tension axes should also be considered.…”

“…The starting configuration, which is not yet a composite, but just the precursor—a system of graphene flakes with Ni nanoparticles inside each flake—is shown in Figure 1 , stage A . Note that in previous studies [ 39 , 40 , 41 ] it was shown that to obtain a Ni/graphene composite with high strength, it is necessary to take into account the difference in the diameter of Ni nanoparticle and the diameter of the rolled graphene flake. If the diameter of the nickel nanoparticle is large, then the graphene flake completely covers the nanoparticle, which makes the formation of strong bonds between the graphene flakes difficult, and therefore, complicates the composite fabrication.…”

Влияние Количества Атомов Металла На Механические Свойства Композита Никель/Скомканный Графен

“…Анализ ближайших соседей подтвердил, что большинство атомов углерода в этих условиях изменяют свою гибридизацию с sp 2 на sp 3 . С увеличением степени деформации чешуйки графена начинают разрушаться посредством формирования углеродных цепочек разной длины, что является известным «трикотажеподобным» механизмом разрушения графена [25]. Такие одноатомные углеродные цепочки образуются при больших растяжениях непосредственно перед разрушением [30,31].…”

“…В данной работе методом молекулярной динамики исследуется влияние количества атомов металла на механические свойства композита никель/скомканный графен. Одним из перспективных методов получения композитов металл/графен является отжиг с последующим гидростатическим сжатием при повышенных температурах [23][24][25]. Для получения композита используются свернутые чешуйки графена, заполненные наночастицами никеля разного размера, в условиях высокотемпературного гидростатического сжатия.…”