Alumina ceramic body
AssigneeNgk Spark Plug Co., Ltd.
InventorsMinato Ando, Masaaki Ito, Fumio Mizuno
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Abstract
A dielectric alumina ceramic body having a constant dielectric loss tangent tan .delta. is obtained by sintering a composition consisting essentially of: 100 parts by weight of a ternary formulation consisting of 92.4 to 98.7 mol % Al.sub.2 O.sub.3, at least 0.5 mol % CaO, and 1.3 to 7.6 mol % TiO.sub.2 ; and at least one selected from the group consisting of Cr.sub.2 O.sub.3 and NiO subject to the relation of: ##EQU1## where x is the weight part of Cr.sub.2 O.sub.3 per 100 parts by weight of said formulation, y is the weight part of NiO per 100 parts by weight of said formulation, and z is the mol % of Al.sub.2 O.sub.3 in the formulation, provided that x.gtoreq.0 and y.gtoreq.0, except x=y=0.
Claims6
An alumina ceramic body obtained by sintering a composition consisting essentially of:
- 100 parts by weight of a ternary formulation consisting of 92.4 to 98.7 mol% Al.sub.2 O.sub.3, and 1.3 to 7.6 mol% in total of CaO and TiO.sub.2, provided that the CaO is at least 0.5 mol%;
- and
- at least one selected from the group consisting of Cr.sub.2 O.sub.3 and NiO subject to the relation of:
- ##EQU11## where x is the weight part of Cr.sub.2 O.sub.3 per 100 parts by weight of said formulation, y is the weight part of NiO per 100 parts by weight of said formulation, and z is the mol% of Al.sub.2 O.sub.3 in the formulation.
Dependencies are inferred from the claim text.