Sintered alumina-based ceramics and process for producing same
AssigneeNgk Spark Plug Co., Ltd.
InventorsHiroshi Yamamoto, Satoshi Iio
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Abstract
Alumina-based ceramics are thermally stable because of their high melting point and excellent materials in wear resistant properties and chemical stability. However, they contradictly have such a problem that fracture toughness is low, and its improvement is desired. The present invention provides such sintered alumina-based ceramics and their production process that have rendered to grow alumina grains anisotropically and can simultaneously attain high flexural strength and fracture toughness by sintering the formed mixture comprising Al.sub.2 O.sub.3, 0.05-2.5 mol % of VA metal oxide and 0.01-4 mol % SiO.sub.2, relative to Al.sub.2 O.sub.3, respectively.
Claims11
A process for producing a sintered alumina-containing ceramics, comprising:
- forming a mixture comprising Al.sub.2 O.sub.3, a VB metal oxide and SiO.sub.2 and
- sintering the formed mixture, at a temperature of 1,320 to 1,600.degree. C. under a condition that alumina grains are grown anisotropically to provide said sintered alumina-containing ceramic
- wherein said sintered alumina-containing ceramic has a flexural strength at room temperature of not less than 500 MPa and a fracture toughness of not less than 5 MPa m.sup.0.5.
The process of claim 6, wherein said oxide of the group VB element is present in an amount of 0.05 to 2.5 mol parts, and said SiO.sub.2 is present in an amount of 0.01 to 4 mol parts, relative to 100 mol parts Al.sub.2 O.sub.3, respectively.
Dependencies are inferred from the claim text.