A strategy for fabricating textured silicon nitride with enhanced thermal conductivity

C-axis textured Si3N4 with a high thermal conductivity of 176 W m(-1) K-1 along the grain alignment direction was fabricated by slip casting raw alpha-Si3N4 powder seeded with near-equiaxed beta-Si3N4 particles and Y2O3-MgSiN2 as sintering additives in a rotating strong magnetic field of 12 T, followed by gas pressure sintering at 1900 degrees C for 12 h at a nitrogen pressure of 1 MPa. The green material reached a relative density of 57%, with slip casting and the sintered material exhibited a relative density of 99% and a Lotgering orientation factor of 0.98. The morphology of the beta-Si3N4 seeds had little effect on the texture development and thermal anisotropy of textured Si3N4. The technique developed provides highly conductive Si3N4 with conductivity to the thickness direction, which is a major advantage in practical use. The technique is also simple, inexpensive and effective for producing textured Si3N4 with high thermal conductivity of over 170 W m I K-1. (C) 2014 Elsevier Ltd. All rights reserved.