Low-expansion ceramics and method of producing the same
First Claim
1. 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 (Al2 O3), and 30 to 80% by weight of titanium in terms of titanium oxide (TiO2), 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×
- 10-7 (1/°
C.) in a temperature range of 25°
C. to 800°
C. and a melting point of not lower than 1,500°
C.
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Abstract
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 (Al2 O3), and 30 to 80% by weight of titanium in terms of titanium oxide (TiO2), 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 20×10-7 (1/°C.) in a temperature range of 25° C. to 800° C. and a melting point of not lower than 1,500° C., wherein the magnesium-alumium-titanate phase as the major component of the crystalline phase thereof is given by a chemical formula Mg10x Al8y Ti5(1-x-y) O.sub.(10+2y), here 0.02≦x≦0.20, 0.10≦y≦0.68, and 0.20≦(x+y)≦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 (TiO2); 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° C. to 1,700° 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 20×10-7 (1/° C.) in a temperature range of 25° C. to 800° C., and a melting point of not lower than 1,500° 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.
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Citations
12 Claims
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1. 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 (Al2 O3), and 30 to 80% by weight of titanium in terms of titanium oxide (TiO2), 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×
- 10-7 (1/°
C.) in a temperature range of 25°
C. to 800°
C. and a melting point of not lower than 1,500°
C. - View Dependent Claims (2, 3, 4, 5, 6)
- 10-7 (1/°
-
7. 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;
- shaping the batch;
drying the body thus formed, and firing the shaped body at 1,300°
C. to 1,700°
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×
10-7 (1/°
C.) in a temperature range of 25°
C. to 800°
C., and a melting point of not lower than 1,500°
C. - View Dependent Claims (8, 9)
- shaping the batch;
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10. 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×
- 10-7 (1/°
C.) in a temperature range of 25°
C. to 800°
C., and a melting point of not lower than 1,500°
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;
shaping said batch into a body;
drying said body thus formed, and firing the shaped body at 1,300°
C. to 1,700°
C. for 0.5 to 48 hours. - View Dependent Claims (11, 12)
- 10-7 (1/°
Specification