Physicists find weak spots in ceramic/graphene composites

phys.org | 9/23/2019 | Staff
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Physicists and materials scientists from Peter the Great St.Petersburg Polytechnic University (SPbPU) analyzed the structures in nanomaterials made of ceramic and graphene plates, in which cracks appear most frequently. The results of the first trial of the model, that describes this regularity, were published in the Mechanics of Materials Journal. This model will help in creation of crack-resistant materials. The research was supported by the Russian Science Foundation grant.

Graphene is the lightest and strongest carbon composite. Moreover, it has a very high electrical conductivity. Because of these characteristics graphene is often included in the composition of new ceramic-based materials. Ceramics are resistant to high temperatures, and, if carbon modifications are added, the composites become multifunctional. In the future they can be used in production of flexible electronic devices, sensors, in construction and aviation.

Studies - Composites - Characteristics - Graphene - Proportion

It is known from many experimental studies of such composites that their mechanical characteristics are set by the graphene proportion in the composition and by the size of graphene plates allocated in the ceramic matrix. For example, in the case of low graphene concentration, high crack resistance was achieved with the help of long plates. However, in one of the recent experiments of synthesis of materials from alumina ceramics and graphene, the opposite effect was shown: as the plates were bigger, the crack resistance was weaker. The researchers from Saint Petersburg have developed a theoretical model that explains this paradox.

The physicists supposed that the formation of cracks in the composites is connected with the boundaries of so-called ceramic grains—microscopic crystals that form the material. Graphene plates in the composites can be located both at the boundaries of ceramic grains and inside grains. In the course of the tensile deformation of nanocrystalline materials, the grains slide relative to each other, and the cracks spread over their boundaries. But why...
(Excerpt) Read more at: phys.org
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