SHS in the Si–N–O System Containing Iron Salts

Abstract—SHS in 3Si–SiO₂–nAdd mixtures, where Add = FeCl₃⋅6H₂O or Fe₂(C₂O₄)₃⋅5H₂O and n = 0.015–0.09 М, under 10 MPa of nitrogen gas was studied by XRD, SEM/EDS, and chemical analysis. The addition of gasifying salts decreased combustion temperature and improved phase composition of combustion products. In case of FeCl₃⋅6H₂O and n = 0.09 М, total yield of silicon oxynitrides Si₂N_2.2O_0.8 and Si₂N₂O attained a value of 94 wt %, due to the presence of added iron. Crystal structure of the earlier unknown Si₂N_2.2O_0.8 phase detected in combustion products derived from 3Si–SiO₂–nFeCl₃⋅6H₂O mixtures was established by XRD analysis and crystallographic modeling.