| abstract |
Disclosed are low expansion, chemically resistant, ceramic articles containing keatite as the principal crystalline phase. The articles are prepared from compositions in the Li 2 O.Al 2 O 3 .SiO 2 field. In preparing this ceramic article, a glass having the desired composition is formed into the appropriate shape by molding the molten glass, compaction and sintering of glass particles or by other conventional glass and ceramic forming processes. The article thus formed is then crystallized to keatite solid solution by an appropriate heat treatment followed by acid leaching in a strong but diluted aqueous acid to produce a ceramic material having the hydroxy aluminosilicate crystalline structure. The hydroxy aluminosilicate ceramic article is then thermally dehydrated to produce a ceramic article containing keatite as a crystalline phase together with mullite with or without the presence of other phases such as amorphous or glassy SiO 2 , quartz and nucleants. |