Theoretical analysis of Si3N4/TiC interfacial properties and material preparation

Abstract

Computer simulation plays an instrumental role in modern tool material design. In this study, we have calculated the temperature and pressure conditions for the phase transition of Si3N4 from α to β using first principles. The simulation results show that the phase transition temperature is 1330 K at a phase transition pressure of 32 MPa. The modulus of elasticity, hardness, ductile/brittle properties (B/G), Poisson's ratio, elastic anisotropy, and phonon spectral curves at the phase transition point were also calculated for the material at temperatures ranging from 873 K to 2073 K. According to the phase transition conditions, the surface energies of β-Si3N4 and TiC interfaces were calculated, and 4-layer models of Si3N4/TiC interfaces were constructed. The total energy and adhesion work of the Si3N4(110)/TiC(100) interface were analyzed by molecular dynamics. The results show that the Si3N4(110)/TiC(100) interface exhibits the maximum total energy and adhesion work of 12,806.62 eV and 2.33 J/m2, respectively, indicating that the interface bond was the most stable. Furthermore, the mechanical properties of different interface models were calculated and compared. The effects of Si3N4(110)/TiC(100) interfacial 5-layer and 6-layer crystalline surfaces and Si and Ti vacancy defects on the mechanical properties of the interfacial model were further investigated. The Si3N4/TiC composite ceramic tool material was prepared experimentally based on the results of simulation, and the properties show reasonable agreement.