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http://dx.doi.org/10.6111/JKCGCT.2020.30.4.150

Effect of Co2O3 addition on liquid phase sintering behavior and mechanical properties of commercial alumina  

Oh, Bok Hyun (Dept. of Advanced Materials Science and Engineering, Mokpo National University)
Yoon, Tae-Gyu (Mokpo Office, DaeKyung Semco., Ltd)
Kong, Heon (Research Institute of Ceramic Industry and Technology, Mokpo National University)
Kim, Nam-Il (Research Institute of Ceramic Industry and Technology, Mokpo National University)
Lee, Sang-Jin (Dept. of Advanced Materials Science and Engineering, Mokpo National University)
Publication Information
Journal of the Korean Crystal Growth and Crystal Technology / v.30, no.4, 2020 , pp. 150-155 More about this Journal
Abstract
Alumina (Al2O3) is mainly used as a structural ceramic material and to have good mechanical properties requires a dense microstructure. In commercial fabrication, the liquid phase sintering process is adjusted to reduce the sintering temperature of alumina. In this study, the effect of added amounts of cobalt oxide as a coloring agent on the microstructure and mechanical properties was investigated in the CaO-SiO2-MgO-system liquid phase sintering of 92 % alumina at various sintering temperatures. When 11 wt% Co2O3 was added, a rearrangement of alumina particles, which is the main densification step in liquid phase sintering, occurred from a sintering temperature of 1200℃. Solution re-precipitation and coalescence steps followed from 1300℃ with the grain growth of alumina particles. The addition of excess Co2O3 and sintering temperatures above 1400℃ resulted in a decrease in sintered density and Vickers hardness, because of the low viscosity of the liquid phase. In 92 % alumina with the addition of 11 wt% Co2O3, a sintered density and Vickers hardness of 3.86 g/㎤ and 12.32 GPa, respectively, were obtained at a sintering temperature of 1350℃.
Keywords
Alumina; Cobalt oxide; Liquid-phase sintering; Densification; Vickers hardness;
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