Fabrication of High Thermal Conductivity β-Si₃N₄ Ceramics at Relatively Low Temperature Using MgSiN₂ as Additives

Abstract

Silicon nitride ceramics with MgSiN2 as additives were sintered by hot pressing at 1600° ~ 1750 °C for 1-12 h under uniaxial pressure of 20 MPa. The specimens were characterized by x-ray diffraction, scanning electron microscopy, transmission electron microscopy and photothermal deflection spectroscopy. After sintered at 1750°C for 1 h, the thermal conductivity of the material was 90 W·m-1·K-1. The thermal conductivity could remarkably increase to 120 W·m-1·K-1 by prolonging the dwell time from 1 h to 12 h. The present work demonstrated that MgSiN2 additives were effective to improve the thermal conductivity of β-Si3N4 ceramic.

ZrSi2–MgO as novel additives for high thermal conductivity of β‐Si3N4 ceramics

“…For instance, the thermal conductivity of Si 3 N 4 ceramics can be improved by the use of MgSiN 2 instead of MgO. With the addition of nitride additives the increased N/O ratio in the grain boundary glassy phase was found, thus the grain growth was promoted and the grain lattice was purified . Recently, Li substituted Y 2 O 3 by Y 2 Si 4 N 6 C and demonstrated that Y 2 Si 4 N 6 C reacted with inherent SiO 2 to form liquid phase Y 2 Si 3 O 3 N 4 and volatile CO(g) resulting in a decrease of oxygen and an increase of N/O ratio in the liquid phase.…”

“…With the addition of nitride additives the increased N/O ratio in the grain boundary glassy phase was found, thus the grain growth was promoted and the grain lattice was purified. 18,19,29 Recently, Li substituted Y 2 O 3 by Y 2 Si 4 N 6 C and demonstrated that Y 2 Si 4 N 6 C reacted with inherent SiO 2 to form liquid phase Y 2 Si 3 O 3 N 4 and volatile CO(g) resulting in a decrease of oxygen and an increase of N/O ratio in the liquid phase. The densified Si 3 N 4 ceramics exhibiting 120 W·(m·K) −1 with enlarged grains, reduced lattice oxygen content, increased grains contiguity and more crystallized intergranular phase were fabricated.…”

Effect of the binary nonoxide additives on the densification behavior and thermal conductivity of Si3N4ceramics

“…The densified Si 3 N 4 ceramics possessing 120 W m −1 K −1 with reduced lattice oxygen content, enhanced grains contiguity, and decreased glassy phase were fabricated 21 . Besides, many studies have demonstrated that the substitution of MgO by MgSiN 2 induced a nitrogen‐rich liquid phase, which would inhibit the oxygen dissolution, thus benefit the thermal conductivity of Si 3 N 4 ceramics 16,22,23 . Apart from fluorides and nitrides, our previous work demonstrated that ZrSi 2 eliminated inherent SiO 2 and in situ generated ZrO 2 and β‐Si 3 N 4 grain seeds resulting in a decrease in oxygen and an increase in N/O ratio in the liquid phase.…”

“…21 Besides, many studies have demonstrated that the substitution of MgO by MgSiN 2 induced a nitrogen-rich liquid phase, which would inhibit the oxygen dissolution, thus benefit the thermal conductivity of Si 3 N 4 ceramics. 16,22,23 Apart from fluorides and nitrides, our previous work demonstrated that ZrSi 2 eliminated inherent SiO 2 and in situ generated ZrO 2 and β-Si 3 N 4 grain seeds resulting in a decrease in oxygen and an increase in N/O ratio in the liquid phase. Benefit from enlarged purified grains, reduced oxygen dissolution, increased grains contiguity, and the densified Si 3 N 4 ceramics with a thermal conductivity of 113 W m −1 K −1 were achieved.…”