Effect of Heating Rate on Spark Plasma Sintering of a Nanosized -Si3N4-Based Powder
A nanosized -Si3N4-based powder doped with sintering additives of 6 wt% Al2O3 and 8 wt% Y2O3 were sintered by spark plasma sintering at different heating rates. The in situ shrinkage curves were measured to identify the densification mechanism during the rise in temperature. At slower heating rates (50 and 100°C/min), the nanosized grains are maintained after sintering at 1600°C for 5 min, while anisotropic grain growth is accelerated above 1500°C by applying a rapid heating cycle (200°C/min). In addition to the dynamic Ostwald ripening that occur during the sintering process, the presence of Morié fringes and dislocations is attributed to grain rotation and misfit strain between the subgrains and elongated, large grains. Grain coalescence is found to occur in the rapid heating process.
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Document Type: Research Article
Department of Materials Science and Engineering, National Cheng-Kung University, Tainan 701, Taiwan, Republic of China
Department of Mechanical Engineering, National Chin-Yi University of Technology, Taiping, Taichung 411, Taiwan, Republic of China
State Key Lab of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
Publication date: 2011-04-01