Interface engineering of graphene nanosheet reinforced ZrB2 composites by tuning surface contacts

Abstract

The mechanical properties of heterophase interfaces are critically important for the behaviour of graphene-reinforced composites. In this work, the structure, adhesion, cleavage and sliding of heterophase interfaces, formed between a ZrB 2 matrix and graphene nanosheets, are systematically investigated by density functional theory, and compared to available experimental data. We demonstrate that the surface chemistry of the ZrB 2 matrix material largely shapes the interface structures (of either Zr-C-Zr or B-C-B type) and the nature of the interfacial interaction. The Zr-C-Zr interfaces present strong chemical bonding and their response to mechanical stress is significantly influenced by graphene corrugation. In contrast B-C-B interfaces, interacting through the relatively weak π-π stacking, show attributes similar to 2D materials heterostructures. Our theoretical results provide insights into the interface bonding mechanisms in graphene/ceramic composites, and emphasize the prospect for their design via interface engineering enabled by surface contacts. 1 arXiv:1904.09008v1 [cond-mat.mtrl-sci] Within the last ten years, the use of graphene as nanofiller in ceramic matrix composites (CMCs), the so called GCMC materials, has attracted plenty of research interest. They find application in various industry sectors such as aerospace, automotive, energy & power, micro-electronics and pharmaceutical. 1-4 In addition to the excellent mechanical (a tensile strength of 130 GPa and a Young's modulus of 1 TPa), electronic and thermal properties,the extremely high specific surface area (2630 m 2 g −1 ) of graphene provides great capacity for functionalizing and bonding to the surrounding ceramic matrices. 5,6 For instance, the fracture toughness parameter, K IC , can be improved by as much as 235 % for only a 1.5 vol% addition of graphene in a Si 3 N 4 matrix 4 . Toughness improvement is also found for zirconium diboride (ZrB 2 ) 7-9 silicon carbide 10 , tantalum carbide 11 and alumina 12 . At the same time, the addition of graphene can also suppress the growth of unwanted oxide layers and refine the ceramic grains 7,13 . Last but not least, the GCMCs developed with hierarchical architectures can simultaneously improve the mechanical and functional properties 8,14,15 .Among various ceramic materials that can be benefited from graphene-based nanofillers, ZrB 2 classified as ultra-high temperature ceramic (UHTC), is one of the most promising structural ceramics for aerospace propulsion systems 16,17 . It exhibits unique combination of high melting point (T m ∼ 3246°C), chemical inertness, effective wear and environment resistance. However, the relatively weak fracture toughness and the drop of flexural strength and oxidation resistance at high temperatures 18 are awaiting further improvement. Adding continuous fibers (for enhancing fractural toughness and flexural strength) 19 and nano-particles (such as SiC for improving oxidation resistance) 20 can partially overcome these issues. Very

Study of Preparation, Properties and Applications of Graphene

“…The mechanical properties of heterogeneous interfaces are critical to the performance of graphite reinforced composites. Zhang et al [8] set graphene between two stable layers and made 12 interface models ZrB2 surfaces. Using density functional theory, they systematically studied the structure, adhesion, cleavage and sliding of heterogeneous interfaces between ZrB2 matrix and graphene nanoplates, and compared them with existing data.…”