YUAN Zheng 1, CHENG Lei 1，LIU Xiaopan 1，GAO Pengzhao 1, 2，XU Moyu 1，XIAO Hanning 1
(1. College of Materials Science and Engineering, Hunan University, Changsha, 410082, Hunan, China; 2. Hunan Province Key Laboratory for Spray Deposition Technology and Application, Hunan University, Changsha 410082, Hunan, China)
Abstract: In this paper, the MoSi2-RSiC composites were prepared via direct melt infiltration (MI) and precursor infiltration pyrolysis (PIP)-direct melt infiltration (MI), where recrystallized silicon carbide (RSiC) works as matrix. Effects of infiltration temperature, matrix density and preparation process on the composition, microstructure and electrical conductivity of the composites were investigated. Furthermore, semi quantitative calculation and modified mixing rule were introduced to explore the influencing factors of conductive behavior of composites. Results show that MoSi2-RSiC composites fabricated via these two methods both possess three-dimensional interpenetrating network structures, and composites obtained via PIP-MI method owns excellent interfacial combination. The volume resistivity of the composites decreasesd with the decreasing of the matrix density and the increasing of the infiltration temperature, the volume resistivity of MS-2.30-2050 was 9.67×10−3 Ω·cm, which was 1/1180 of the corresponding matrix. The interpenetrating network structure has remarkable influence on the conductive behavior of the composites. When the density of the matrix is 2.62 g/cm3, I1 is 0.64. The effect of the interface bonding on the conductive behavior of the composites is mainly affected by the thickness of the interface layer and the volume fraction of the infiltrated phase. With the density of the matrix increasing, the interface bonding factors increase first and then decrease. The effect of the interpenetrating network structure on the conductivity was stronger than the interfacial performance.
Key words: MoSi2-RSiC composites; electrical conductivity; semi-quantitative calculation; modified mixing rule