First principles calculation of interfacial stability, energy and electronic properties of SiC/ZrB2 interface

Interfacial models of SiC/ZrB2 composite coating were studied by first-principles calculations based on density functional theory (DFT). The cubic SiC and hexagonal ZrB2 were selected in our work, and twelve types of SiC (111)/ZrB2 (0001) interface structures were investigated in consideration of four different terminations and three stacking sequences. The cohesive energy (Was), interfacial energy (gamma(int)), and electronic structure of the SiC/ZrB2 interfaces were all calculated. The results show that the ZrB2 (0001) surface with 9 layers exhibits bulk-like interior characteristic. Among the interfaces of C/Zr terminated hcp-stacked (CZH), Si/Zr terminated hcp-stacked (SZH), C/B terminated center-stacked (CBC) and Si/B terminated center-stacked (SBT), the CZH interface has the largest Wad (6.28 J/m(2)) and thus is of the best stability. Over the range of zirconium chemical potential, the gamma(int) of CZH, SZH, CBC and SBT interfaces are -0.31-2.50 J/m(2), 1.07-3.88 J/m(2), 2.85-5.66 J/m(2) and 2.32-5.13 J/m(2), respectively. The calculated electronic properties reveal that, the CZH, CBC and SBT interfaces mainly contain covalent bonding, while the SZH one primarily consists of metallic bonding.