Oxidation-induced mechanical deterioration and hierarchical cracks in glassy carbon

Glassy carbon (GC) is a widely used non-graphitizing carbon material, and has excellent resistances to physical and chemical attacks. However, as other carbon materials, GC is subject to the oxidation-induced deterioration. Many researchers have been trying to study the underlying oxidation mechanisms, but a convenient in-situ technique is unavailable. This paper aims to provide a facile method to investigate the mechanical property change of GC subjected to oxidation. It was found that during cyclic heating/cooling from room temperature to 500 °C, the elastic modulus decreased permanently. After two cycles, notable hierarchical cracking started on the surface, forming regular surface patterns through cracking bifurcations and leading to delamination. The oxidation of GC was proved by energy dispersion spectrum elemental analysis and comparative test with protective argon gas. The study concluded that the formation of surface oxidation layer is the main cause of mechanical deterioration and hierarchical cracking.