Low-expansion ceramics and method of producing the same

A method of producing low-expansion ceramics comprising steps of preparing a batch of compounds so as to provide a chemical composition of 1.5 to 20% by weight of magnesia (MgO), 8 to 68% by weight of alumina (Al.sub.2 O.sub.3), 24 to 80% by weight of titanium in terms of titanium oxide (TiO.sub.2), and 0.5 to 20% by weight of iron in terms of ferric oxide (Fe.sub.2 O.sub.3);

• plasticizing the batch if necessary and shaping the batch;
• drying the body thus formed;
• and firing the formed body at 1,300.degree. C. to 1,700.degree. C. for 0.5 to 48 hours, thereby having a coefficient of thermal expansion of less than 20.times.10.sup.-7 (1/.degree.C.) in a temperature range of 25.degree. C. to 800.degree. C. and a melting point of not lower than 1,500.degree. C., said coefficient of thermal expansion being maintained even after exposure at 1,100.degree. C. for 1,000 hours.

Low-expansion ceramics having a solid solution of magnesium oxide-aluminum oxide-titanium dioxide-iron oxide as the major component of crystalline phase and that the ceramics have a coefficient of thermal expansion of not more than 20.times.10.sup.-7 (1/.degree.C.) in a temperature range of 25.degree. C. to 800.degree. C. and a melting point of not lower than 1,500.degree. C., said coefficient of thermal expansion being maintained even after exposure 1,100.degree. C. for 1,000 hours, said low-expansion ceramics being made by the process comprising the steps of preparing a batch of compounds so as to provide a chemical composition of 1.5 to 20% by weight of magnesia (MgO), 8 to 68% by weight of alumina (Al.sub.2 O.sub.3), 24 to 80% by weight of titanium in terms of titanium oxide (TiO.sub.2), and 0.5 to 20% by weight of iron in terms of ferric oxide (Fe.sub.2 O.sub.3);

• plasticizing the batch if necessary and shaping the batch;
• drying the body thus formed;
• and firing the formed body at 1,300.degree. C. to 1,700.degree. C. for 0.5 to 48 hours.