Fabrication of a novel high electrical conductivity Si3N4 matrix composite with Cu three-dimensional network structure by spark plasma sintering

• Published in: Journal of alloys and compounds 2024-10, Vol.1001, p.175158, Article 175158
• Main Authors: Wu, Dandan, Yan, Yufu, Liu, Zijun, Wang, Chengyong
• Format: Article
• Language: English
• Subjects: Chemical bonding interface; Composite materials; Electrical conductivity; Mechanical properties; Spark plasma sintering; Surfaces and interfaces
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2024.175158

Silicon nitride (Si3N4) ceramic matrix conductive composite materials have shown great promise as conductive layer materials for electrical transmission components. However, existing conductive phases struggle to form a three-dimensional (3D) interconnected network in Si3N4 matrix, resulting in poor electrical conductivity. This study proposed a spark plasma sintering (SPS) process utilizing Si3N4 as the substrate and Cu particles as the reinforcement phase to fabricate a novel electrical conductivity Si3N4/Cu composite material. The results indicated that the diffusion of Si atoms in Si3N4 facilitated the formation of copper silicide (CuiSi) interface between the two constituents during sintering, creating a strong chemical bonding for high conductivity. Simultaneously, composite materials with optimized Cu content formed a 3D interconnect network structure, providing a continuous path for electrical conduction. At Cu content of 30 vol%, the Si3N4/Cu composite exhibited a satisfying electrical conductivity of 295.37 S/m, which was 14 orders of magnitude higher than that of Si3N4. The composites also demonstrated a percolation phenomenon, with a theoretical percolation threshold of Cu particles at just 0.1 vol%, an order of magnitude lower than that of carbon reinforcement particles. Furthermore, an integrated design featuring external insulation and internal conductivity was achieved by wrapping a Si3N4 insulation layer around the conductive Si3N4/Cu composites. The fabricated insulation layer exhibited higher resistivity (1.12×1014 Ω) and a lower wear rate (1.3×10−6 mm3/N·m) compared to some contemporary insulation ceramics, while the conductive layer had a lower calorific value, making them excellent candidates for electrical transmission component materials. [Display omitted] •High electrical conductivity Si3N4 matrix composites with a Cu 3D network structure were successfully fabricated.•Si3N4/Cu composite offered maximum electrical conductivity of 295.37 S/m, 14 orders of magnitude higher than Si3N4.•The copper silicide formed at the interface between Si3N4 and Cu, creating a strong chemical bonding.•The insulating and conductive integrated device was developed.