Effect of glass additives on the strength and toughness of polycrystalline alumina |
| |
Affiliation: | 1. Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, PR China;2. State Key Laboratory of New Ceramics & Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, PR China |
| |
Abstract: | The effect of stress at grain boundaries on the mechanical properties of alumina ceramics was investigated. Residual stresses at grain-boundaries resulted from a mismatch in thermal expansion coefficient (TEC) between the alumina matrix and the glass-phase segregated at grain-boundaries. The BaO–Al2O3–SiO2 (BAS) system and the Li2O–Al2O3–SiO2 (LAS) system glasses were chosen to have a higher and a lower TEC than that of alumina, respectively, resulting in microscopic tensile and compressive stresses at grain-boundaries for Al2O3/BAS and Al2O3/LAS composites, respectively. The experimental results showed that the Al2O3/BAS composite fractured intergranularly with a fracture toughness higher than that of monolithic alumina. On the other hand, the Al2O3/LAS composite experienced transgranular fracture and high bending strength despite its low toughness. Both composites could be sintered to full density at 1500°C for 2 h due to the presence of a liquid phase. It was concluded that strengthening and toughening of alumina ceramics could be tailored by designing their grain-boundary microstresses. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |
|