Mechanical properties of computationally designed novel carbon enriched Si1-xCx ceramics: A molecular dynamics simulation study

Silicon Carbide (SiC) exhibits excellent mechanical, thermal and electrical properties. Low fracture toughness is one of the limiting properties of SiC that hinders its widespread applications. Recent studies suggest that controlled alteration of local micro-structure may lead to dislocation nucleation in certain SiC poly-types. Here, we report classical molecular dynamics simulations results to demonstrate mechanical behavior of a new type SiC-based "C enriched" ceramics where certain Si atoms are substituted by C atoms. We studied four different systems with different fraction of "C" enrichment, namely 10%, 20%, 30% and 40%. Thermodynamic viability of such novel micro-structures have been studied recently (Adnan and Ferdous, 2015). Significant effects of "C" enrichment on the tensile and shear properties of the new ceramic materials have been observed. Compared to pure SiC, the tensile strengths of enriched systems always increase but to a different extent depending on the amount of enrichment. Shear strengths, however, tend to decrease with increase in carbon enrichment until enrichment is 40%. The elastic constants C-11 and C-44 were measured and both increase significantly with carbon enrichment. The area under the stress-strain tensile and shear curves have been estimated to assess the tensile and shear toughness properties and it has been found that both types of toughness increase significantly with carbon enrichment. (C) 2015 Elsevier B.V. All rights reserved.