Restraining of calcium contamination in near‐net shape alumina ceramics during slip casting |
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Authors: | Daniel Drdlik Jakub Rolecek Katarina Drdlikova David Salamon |
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Affiliation: | 1. Department of Advanced Ceramic Materials, CEITEC ‐ Central European Institute of Technology, Brno University of Technology, Brno, Czech Republic;2. Department of Technology, Military Research Institute, Brno, Czech Republic |
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Abstract: | The traditional method for shaping ceramics is by slip casting on gypsum molds; however, its application for near‐net shaping of ceramic components is limited due to contamination by calcium ions. The focus of this study is the modification of the mold to limit Ca2+ contamination and to maintain favorable sucking properties. Cement was added to a standard gypsum mold to suppress its erosion, and a decrease in the sucking rate was observed due to its reduced macroporosity. The highest values of green densities were obtained at gypsum/cement weight ratios of 90/10 and 70/30. The microstructure analysis showed that alumina blocks prepared from the molds containing higher quantities of cement (30 or 50 wt%) were resistant to abnormal grain growth caused by Ca2+ contamination from the gypsum. The gypsum/cement mixtures for making molds for slip casting significantly limit mold erosion due to a lower sucking rate and abnormal grain growth of the slip cast samples because of the decreased diffusivity of Ca2+ ions. Therefore, the present modification of the mold renders the slip casting method more suitable for the near‐net shaping of ceramics. |
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Keywords: | alumina contamination density microstructure slip casting |
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