The importance of amorphous intergranular films in self-reinforced Si3N4 ceramics
The importance of amorphous intergranular films in self-reinforced Si3N4 ceramics
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DOI：
10.1016/s1359-6454(00)00236-6
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发表时间：
2000-12
期刊：
影响因子：
9.4
通讯作者：
P. Becher;G. S. Painter;E. Sun;Chun-Hway Hsueh;M. Lance
中科院分区：
文献类型：
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作者：
P. Becher;G. S. Painter;E. Sun;Chun-Hway Hsueh;M. Lance
通过调整细长桥晶粒的尺寸和数量可以获得高断裂强度和高韧性的β-Si3N4陶瓷。然而，这些桥接机制依赖于增强颗粒与基体的脱粘来增加韧性。结果表明，界面脱粘受到无定形晶粒间薄膜中掺入的烧结助剂的影响。在一种情况下，晶间玻璃和增强晶粒之间的界面强度随着界面外延β-SiAlON层的铝和氧含量的增加而增加。另一方面，在晶粒间薄膜中掺入氟使得裂纹能够绕过晶粒。原子簇计算表明，这两个脱粘过程与（1）玻璃/晶体界面上的 Si-O 和 Al-O 与外延 SiAlON 层之间的强键合有关，以及（2）当二氟取代桥接氧时，晶粒间薄膜的非晶网络减弱。
High-fracture-strength and high-toughness β-Si3N4ceramics can be obtained by tailoring the size and number of the elongated bridging grains. However, these bridging mechanisms rely on debonding of the reinforcing grains from the matrix to increase toughness. Interfacial debonding is shown to be influenced by sintering aids incorporated in the amorphous intergranular films. In one case, the interface strength between the intergranular glass and the reinforcing grains increases with the aluminum and oxygen content of an interfacial epitaxial β-SiAlON layer. In another, the incorporation of fluorine in the intergranular film allows the crack to circumvent the grains. Atomic cluster calculations reveal that these two debonding processes are related to (1) strong Si–O and Al–O bonding across the glass/crystalline interface with an epitaxial SiAlON layer and (2) a weakening of the amorphous network of the intergranular film when difluorine substitutes for bridging oxygen.