Diamond & Related Materials 111 (2021) 108225 Available online 15 December 2020 0925-9635/© 2020 Elsevier B.V. All rights reserved. Quasi-static compression properties of graphene aerogel Lulu Niu a , Jing Xie a, * , Pengwan Chen a, * , Guangyong Li b , Xuetong Zhang b a State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing, China b Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou, China A R T I C L E INFO Keywords: Graphene aerogel Axial compression Microstructure evolution Negative structural Poisson’s ratio Toughness ABSTRACT Graphene aerogel (GA) is a promising candidate for energy absorption purposes because of its very low density, high specific surface area and porous structure. GA samples, prepared by the Sol-Gel method, were tested under quasi-static compression, and characterized via surface area analyzer, as well as scanning electron microscopy and transmission electron microscopy. The results show that 98% (and above) porous GA samples, whose elastic modulus is 2.9 MPa, can support at least 35,000 times its weight. Scaling analysis shows that the mechanical properties of GA are superior to those of conventional polymeric open-cell foams. The GA samples exhibit a negative structural Poisson’s ratio under the uniaxial compression test, which is most likely due to the bread-like microstructural evolution. Due to the mesopores of the GA sample as well as the negative structural Poisson’s ratio, the GA has considerable toughness. 1. Introduction Graphene is a one-atom-thick layer of carbon atoms (approximately 0.4 nm) arranged in a hexagonal lattice [1]. As a two-dimensional (2D) nanomaterial, it has been the focus of intense interest since its discovery in 2004 due to its remarkable carrier mobility (10,000 cm 2 ∙V 1 ∙s 1 ), superior thermal conductivity (5000 W∙m 1 ∙K 1 ) [2] and excellent mechanical strength (130 GPa) [3]. A current challenging problem is about how to overcome the π-π stacking interactions between graphene sheets and convert the 2D graphene sheet to a bulk graphene material in order to fully exploit the properties of graphene. Certain methodologies have been devised to prepare three-dimensional (3D) structure gra- phenes such as aerogels [4], hydrogels [5] and cellular monoliths [6]. Among these structures, the aerogel shows a great promise because it can be lighter than air and has thus attracted much attention in recent years [7]. Aerogels were first synthesized from silica gels by replacing the liquid component with a gas [8]. Nowadays, the aerogels are prepared from molecular precursors (generally graphene oxides) by sol-gel methods and followed by either freeze or supercritical drying to replace the solvents with air [9]. Aerogels exhibit high porosity (>90%), low density (<3 kg∙m 3 ), low thermal, low refractive index and low dielectric constant, which can be are applied in a variety of fields [10], such as energy storage/conversion [11], catalysis [12], environmental remediation [13], sensing devices [14], supercapacitor electrode [15], electromagnetic interference shielding [16]. Aerogels are generally considered as elastic and brittle materials. Several researchers reported that they have synthesized mechanical strong aerogels [17–19], whose elastic modulus (up to 180 MPa) is higher than that of the common silica aerogels (2.25 MPa with a density of 0.1 g∙cm 3 ), but a few orders of magnitude lower compared to dense glasses (68 GPa) or other engineering materials (192 GPa for AISI4000 steel). However, thanks to the high concentration of nano-scale pores, aerogels can be used to capture the high-speed particles. NASA used silica aerogel to capture particles from comet Wild 2 in 2004 [20]. Laboratory hypervelocity impact experiments conducted by Japanese scientists have verified that at impact velocities below 6 km/s the pro- jectiles of aluminum oxide, olivine, or soda lime glass with diameters ranging from 10 to 400 μm were captured without fragmentation by the silica aerogel collector of 0.03 g∙cm 3 [21]. Moreover, researchers re- ported a negative Poisson’s ratio in the graphene-based materials [22–24]. Materials with negative Poisson’s ratio possess enhanced shear resistance, indentation resistance and fracture toughness, which all point to a number of promising applications, particularly in aerospace, biomedicine, defense and intelligent systems [25]. Molecular Dynamics (MD) simulations have shown that the double vacancy defect can be considered as one of the mechanisms causing the negative Poison’s ratio of graphene [26,27]. The Schwartzite model for sp 2 -carbon phases was used to explain the near-zero Poisson ratio of sponge graphene [22]. Scanning electron in situ observations revealed * Corresponding authors. E-mail addresses: [email protected] (J. Xie), [email protected] (P. Chen). Contents lists available at ScienceDirect Diamond & Related Materials journal homepage: www.elsevier.com/locate/diamond https://doi.org/10.1016/j.diamond.2020.108225 Received 22 October 2020; Received in revised form 2 December 2020; Accepted 10 December 2020
Quasi-static compression properties of graphene aerogel
Jun 17, 2023
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