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US 4,307,198 AGranted
Low-expansion ceramics and method of producing the same
AssigneeNGK Insulators, Ltd.
InventorsIsao Oda, Tadaaki Matsuhisa
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AssigneeNGK Insulators, Ltd.
InventorsIsao Oda, Tadaaki Matsuhisa
Estimating the term…
The present invention relates to low-expansion ceramics having a chemical composition of the ceramics essentially consisting of 2 to 20% by weight of magnesia (MgO), 10 to 68% by weight of alumina (Al.sub.2 O.sub.3), and 30 to 80% by weight of titanium in terms of titanium oxide (TiO.sub.2), wherein the major component of crystalline phase thereof is magnesium-alumium-titanate phase, and 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., wherein the magnesium-alumium-titanate phase as the major component of the crystalline phase thereof is given by a chemical formula Mg.sub.10x Al.sub.8y Ti.sub.5(1-x-y) O.sub.(10+2y), here 0.02.ltoreq.x.ltoreq.0.20, 0.10.ltoreq.y.ltoreq.0.68, and 0.20.ltoreq.(x+y).ltoreq.0.70, and a method of producing low-expansion ceramics, said method comprising steps of preparing a batch of compounds so as to provide a chemical composition of 2 to 20% by weight of magnesia, 10 to 68% by weight of alumina, and 30 to 80% by weight of titanium in terms of titanium oxide (TiO.sub.2); plasticizing the batch if necessary and shaping the batch by a means selected from the group consisting of extrusion, pressing, slip casting, and injection molding; drying the body thus formed; and firing the shaped body at 1,300.degree. C. to 1,700.degree. C. for 0.5 to 48 hours, whereby ceramics have a magnesium-aluminum-titanate phase as main component of crystalline phase thereof, 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. The ceramics of the invention can be widely used as ceramics material in the fields where high degree of heat-resistance, thermal shock-resistance, wear-resistance and corrosion-resistance are required.
Low-expansion ceramics having a chemical composition of the ceramics essentially consisting of 2 to 20% by weight of magnesia (MgO), 10 to 68% by weight of alumina (Al.sub.2 O.sub.3), and 30 to 80% by weight of titanium in terms of titanium oxide (TiO.sub.2), wherein the major component of crystalline phase thereof is magnesium-aluminum-titanate phase, and 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.
A method of producing low-expansion ceramics comprising steps of preparing a batch of compounds so as to provide a chemical composition of 2 to 20% by weight of magnesia, 10 to 68% by weight of alumina, and 30 to 80% by weight of titanium in terms of titanium oxide;
Low-expansion ceramics having a magnesium-aluminum-titanate phase as main component of crystalline phase thereof, 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 low-expansion ceramics being produced by a process comprising the steps of preparing a batch of compounds so as to provide a chemical composition of 2 to 20% by weight of magnesia, 10 to 68% by weight of alumina, and 30 to 80% by weight of titanium in terms of titanium oxide;
Dependencies are inferred from the claim text.