First principles modeling and simulation of Zr-Si-B-C-N ceramics: Developing hard and oxidation resistant coatings

Abstract We model amorphous ZrSiBCN ceramics combining ab-initio molecular dynamic simulations with melt-quench and simulated annealing techniques. Starting from the parent composition Zr 42 B 32 C 8 N 18 we systematically increase the Si 3 N 4 content along four different pathways in the composition diagram and evaluate trends in structure and properties. Mixtures of ZrB 2 , ZrN, and ZrC exhibit Zr layers as well as ZrB 2 and ZrN(C) nuclei, but addition of Si 3 N 4 reduces structural order in the models. Elastic moduli decrease with increasing Si 3 N 4 content to values less than expected of a simple mixture model. Thus, while addition of Si 3 N 4 to amorphous ZrBCN coatings may improve oxidation resistance, this needs to be balanced with desired mechanical properties.