Spark Plasma Sintered Silicon Nitride Ceramics with High Thermal Conductivity Using MgSiN ₂ as Additives

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Silicon nitride ceramics were prepared by spark plasma sintering (SPS) at temperatures of 1450°–1600°C for 3–12 min, using α‐Si 3 N 4 powders as raw materials and MgSiN 2 as sintering additives. Almost full density of the sample was achieved after sintering at 1450°C for 6 min, while there was about 80 wt%α‐Si 3 N 4 phase left in the sintered material. α‐Si 3 N 4 was completely transformed to β‐Si 3 N 4 after sintering at 1500°C for 12 min. The thermal conductivity of sintered materials increased with increasing sintering temperature or holding time. Thermal conductivity of 100 W·(m·K) −1 was achieved after sintering at 1600°C for 12 min. The results imply that SPS is an effective and fast method to fabricate β‐Si 3 N 4 ceramics with high thermal conductivity when appropriate additives are used.