First principles study of oxidation resistance of amorphous Si-(B)-C-N materials, and experimental verification

Amorphous silicon boron carbonitride (Si-B-C-N) ceramics offer superior oxidation resistance at high temperatures. These ceramics are excellent candidates for use as coatings in high-temperature applications and other advanced technologies. We investigate the oxidation resistance of amorphous Si-(B)-C-N ceramic materials in a wide range of elemental compositions using density functional theory. We go beyond the empirical experimental results and focus on complete quantitative description of the oxidation onset in terms of the corresponding reaction energies. Several adsorption sites are explored to examine the adsorption behavior of O2 molecules and to identify the most stable adsorption configuration at each surface. Next, we analyze O2 dissociation by examining intermediate configurations at the most stable adsorption sites. We obtain energy barriers of 2.13-3.27 eV (Si-BC-N) and 1.41-1.53 eV (Si-C-N), in both cases increasing with increasing Si/C ratio. These findings align well with our qualitative experimental results, quantify them, and facilitate the comparison of Si-(B)-C-N ceramics with other materials and the full utilization of their application potential.