Effect of oxygen content and surface modification on combustion synthesized β-Si3N4 thermal conductive filler

Silicon nitride (Si 3 N 4 ) is regarded as a promising filler for thermal conductive composites due to its excellent thermal and electrical properties. In this work, the effects of oxygen content and surface modification of combustion synthesized β-Si 3 N 4 filler on the thermal, electrical, and mechanical properties of polydimethylsiloxane (PDMS) composites were investigated. The results demonstrate that an increase in the oxygen content of β-Si 3 N 4 filler leads to a significant deterioration in the thermal conductivity of the PDMS/β-Si 3 N 4 composites, while the dielectric constant decreases accordingly. Surface modification by vinyltrimethoxysilane (VTMS) improves the interfacial bonding between β-Si 3 N 4 filler and PDMS matrix, which increases the filler loading. PDMS composite with a high thermal conductivity of 4.26 Wm −1 K −1 was acquired using the binary filler comprising 64 wt% Al 2 O 3 and 29 wt% β-Si 3 N 4 . This work provides valuable guidance for the application of combustion synthesized β-Si 3 N 4 filler in highly thermal conductive composites.