Effect of Zr on the solid sintering process of SiBCN ceramics: Diffusion couple method experiment and DFT calculation

The impact of Zr addition on the solid sintering process of SiBCN multiphase ceramics was investigated under high temperatures. To gain deep insight, SiBCN-Zr diffusion couple method (sample preparation at 1500-1800 & DEG;C) was utilized in conjunction with first-principles calculations. Significantly, the results demonstrated the formation of SiC and BN as well as ZrC/ZrB2 at the interface of the diffusion couples. Possible mechanisms have been analyzed and proposed. On the one hand, the extensive generations of defects are supposed to facilitate the formation of SiC and ZrC during the preparation of SiBCN amorphous powders. On the other hand, the presence of distinctive BN(C) structures in SiBCN hindered the formation of ZrB2, thus causing a delay in its formation. Through first-principles calculations, remarkable variations in interatomic bonding strengths have been revealed among the different phases at the interface. Specifically, interfaces of ZrC/ZrB2 and SiC exhibit stronger bonding strengths compared to BN and SiC, implying that Zr, and its compounds may act as binding agents.