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Effects of Nanostructure and Coating on the Mechanics of Carbon Nanotube Arrays
Author(s) -
Poelma René H.,
Fan Xuejun,
Hu ZhiYi,
Van Tendeloo Gustaaf,
van Zeijl Henk W.,
Zhang Guo Qi
Publication year - 2016
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201503673
Subject(s) - waviness , materials science , conformal coating , nanostructure , carbon nanotube , composite material , coating , nanoindentation , van der waals force , chemical vapor deposition , elastic modulus , nanotechnology , modulus , porosity , chemistry , organic chemistry , molecule
Nanoscale materials are one of the few engineering materials that can be grown from the bottom up in a controlled manner. Here, the effects of nanostructure and nanoscale conformal coating on the mechanical behavior of vertically aligned carbon nanotube (CNT) arrays through experiments and simulation are systematically investigated. A modeling approach is developed and used to quantify the compressive strength and modulus of the CNT array under large deformation. The model accounts for the porous nanostructure, which contains multiple CNTs with random waviness, van der Waals interactions, fracture strain, contacts, and frictional forces. CNT array micropillars are grown and their porous nanostructure is controlled by the infiltration and deposition of thin conformal coatings using chemical vapor deposition. Flat‐punch nanoindentation experiments reveal significant changes in material properties as a function of coating thickness. The simulations explain the experimental results and show the novel failure transition regime that changes from collective CNT buckling toward structural collapse due to fracture. The compressive strength and the elastic modulus increase exponentially as a function of the coating thickness and demonstrate a unique dependency on the CNT waviness. More interestingly, a design rule is identified that predicts the optimum coating thickness for porous materials.