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Restraining of calcium contamination in near‐net shape alumina ceramics during slip casting
Author(s) -
Drdlik Daniel,
Rolecek Jakub,
Drdlikova Katarina,
Salamon David
Publication year - 2018
Publication title -
international journal of applied ceramic technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.4
H-Index - 57
eISSN - 1744-7402
pISSN - 1546-542X
DOI - 10.1111/ijac.13042
Subject(s) - materials science , gypsum , mold , slip (aerodynamics) , cement , ceramic , metallurgy , microstructure , contamination , grain size , composite material , physics , biology , thermodynamics , ecology
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 Ca 2+ 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 Ca 2+ 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 Ca 2+ ions. Therefore, the present modification of the mold renders the slip casting method more suitable for the near‐net shaping of ceramics.