Abstract An alumina ceramic composition to provide a low dielectric loss in the high frequency region upon sintering, which consists essentially of: 100 parts by weight of a base composition containing therein Al 2 O 3 , CaO and TiO 2 within their respective compositional range; and 0.03 to 3 parts by weight of La 2 O 3 . The base composition is within a range A-B-C-D-E-A in the ternary diagram (Figure) in molar fraction: ______________________________________ Al 2 O 3 CaO TiO 2 ______________________________________
A 99.0 0.5 0.5
B 94.5 3.7 1.8
C 90.0 7.0 3.0
D 90.0 2.0 8.0
E 94.5 1.3 4.2
______________________________________
An alumina ceramic composition consisting essentially of: (a) 100 parts by weight of a base composition consisting essentially of Al 2 O 3 , CaO and TiO 2 within their respective ranges as enclosed by rectilinear lines connecting points A-B-C-D-E-A, each having the undermentioned values in a ternary triangular coordinate system, wherein Al 2 O 3 , CaO and TiO 2 are represented, by three parameters in molar fraction on each of the three coordinates: ______________________________________
Al.sub.2 O.sub.3
CaO TiO.sub.2
______________________________________
A 99.0 0.5 0.5
B 94.5 3.7 1.8
C 90.0 7.0 3.0
D 90.0 2.0 8.0
E 94.5 1.3 4.2 ; and
______________________________________ (b) 0.03 to 3 parts by weight of La 2 O 3 .
Claim 2
Dependent Claim
117 words
An alumina ceramic composition consisting essentially of: (a) 100 parts by weight of a base composition consisting essentially of Al 2 O 3 , CaO and TiO 2 within their respective ranges as enclosed by rectilinear lines connecting points A-B-C-D-E-A, each having the undermentioned values in a ternary triangular coordinate system, wherein Al 2 O 3 , CaO and TiO 2 are represented, by three parameters in molar fraction on each of the three coordinates: ______________________________________
Al.sub.2 O.sub.3
CaO TiO.sub.2
______________________________________
A 99.0 0.5 0.5
B 94.5 3.7 1.8
C 90.0 7.0 3.0
D 90.0 2.0 8.0
E 94.5 1.3 4.2 ; and
______________________________________ (b) 0.03 to 3 parts by weight of La 2 O 3 .
Claim 3
Dependent Claim
61 words
An alumina ceramic composition as defined in claim 1, wherein the proportions of Al 2 O 3 , CaO and TiO 2 are within the ranges defined by a line connecting the following points P-Q-R-S-P in molar fraction: ______________________________________
Al.sub.2 O.sub.3 CaO TiO.sub.2
______________________________________
P 94.9 2.8 2.3
Q 94.0 3.4 2.6
R 94.0 2.2 3.8
S 94.9 2.1 3.0
______________________________________
Claim 4
Dependent Claim
17 words
A sintered alumina ceramic product obtained by sintering the alumina ceramic composition as defined in claim 1.
Claim 5
Dependent Claim
17 words
A sintered alumina ceramic product obtained by sintering the alumina ceramic composition as defined in claim 2.