結晶化したYb_2Si_2O_7粒界相を持つシリサイド粒子強化Si_3N_4複合材料の作製と微構造

概要

論文の詳細を見る
Silicide-particle-reinforced Si_3N_4 composites with a crystallized grain boundary phase of Yb_2Si_2O_7 were synthesized in-situ by hot-pressing Si_3N_4 with the metal oxides M_pO_q (silicide-forming oxides), which can react with Si_3N_4 to form silicide, and Yb_2O_3 as sintering additives. The reaction between Si_3N_4, silicide-forming oxide (Ta_2O_5 or MoO_3) and Yb_2O_3 at high temperatures generated silicide (Ta_3Si or Mo_5Si_3) particles and a grain boundary phase, Yb_2Si_2O_7, simultaneously. The silicide particles mainly existed at the grain boundaries, but a small amount of Ta_3Si particles were detected from Si_3N_4 grains. Ta_3Si particle grew up to a polyhedron shape, but Mo_5Si_3 particle to a spherical shape. To obtain the crystallized grain boundary phase of RE_2Si_2O_7, the molar ratio of Yb_2O_3 to M_pO_q should be adjusted to q/4 (q: the number of oxygen atoms in M_pO_q). However, because a small amount of oxygen was included in Si_3N_4 powder and existed on the surface of Si_3N_4 as SiO_2, the excess SiO_2 reacted with Si_3N_4 to generate a trace of Si_2N_2O grain. In the silicide-Yb_2Si_2O_7-Si_3N_4 composites, the grain boundary phases were crystallized, but thin amorphous films with a thickness of 1nm were detected from the interfaces between the silicide particle, Si_3N_4 grain, and the grain boundary phase of Yb_2Si_2O_7. The dense silicide particles reinforced Si_3N_4 matrix composites can be obtained by using this in-situ synthesis method, and the flexural strength and fracture toughness of Ta_3Si-Yb_2Si_2O_7-Si_3N_4 composite were 1209MPa, and 6.0MPa・m^<1/2>, respectively.
2006-12-01

結晶化したYb_2Si_2O_7粒界相を持つシリサイド粒子強化Si_3N_4複合材料の作製と微構造

スポンサーリンク

概要

著者

関連論文

スポンサーリンク