摘要
Dense Si3N4 - BN composite ceramics were .fabricated by spark plasma sintering at 1 500, 1 600 and 1 650 ℃ under 50 MPa for 5 min using Si3N4 and BN powders as starting materials and 2 mass% Al2O3 and 6 mass% Y2O3 as sintering additives. The volume fraction of BN in Si3N4 -BN composite powders was chosen as 10% , 20% , and 30% , respectively. The results oJ XRD and SEM show that χ-Si3N4 completely turns into β-Si3N4 when the composite ceramics are sintered at 1 650℃; the addition of BN hinders the growth of Si3N4 grains, reigning the structure; Vickers hardness and fracture toughness of the composite ceramics decrease with the increase of BN content.
Dense Si3N4 - BN composite ceramics were .fabricated by spark plasma sintering at 1 500, 1 600 and 1 650 ℃ under 50 MPa for 5 min using Si3N4 and BN powders as starting materials and 2 mass% Al2O3 and 6 mass% Y2O3 as sintering additives. The volume fraction of BN in Si3N4 -BN composite powders was chosen as 10% , 20% , and 30% , respectively. The results oJ XRD and SEM show that χ-Si3N4 completely turns into β-Si3N4 when the composite ceramics are sintered at 1 650℃; the addition of BN hinders the growth of Si3N4 grains, reigning the structure; Vickers hardness and fracture toughness of the composite ceramics decrease with the increase of BN content.
基金
supported by the National Natural Science Foundation of China with grant number of 50374007
