Microstructural and mechanical characterization of carbon aerogels: An in-situ and digital image correlation-based study

Abstract

The mechanical behavior of carbon aerogels is not very well understood, presenting a bottle-neck in synthesizing aerogels for specific applications where mechanical loads play a role. Accordingly, in this paper, three different types of carbon aerogels with varying mechanical properties and flexibility are synthesized and analyzed. The morphology is characterized by using a scanning electron microscope (SEM) and nitrogen adsorption-desorption isotherms. The mechanical behavior is investigated under uniaxial quasistatic compression as well as in-situ compression under a SEM. While in-situ tests reveal microstructural evolution under deformation, the macroscopic deformation is described by the digital image correlation. Based on cyclic compression tests with step-wise increasing strain amplitude, novel empirical relations are proposed to describe the damage characteristics such as energy dissipation and residual deformation. Furthermore, while testing carbon aerogels under tension is not very feasible, three-point bending tests are conducted and the resulting flexural properties of carbon aerogels are identified.