Patent ID: 11905219
Assignee: COORSTEK KK
Field: Materials, metallurgy (Chemistry)
Classification: CPC C | IPC C

Claim 0:
1. An alumina ceramic comprising alumina as a main component, an alkaline earth metal, and an element belonging to period 3, 4 or 5,
wherein the alkaline earth metal and the element belonging to period 3, 4 or 5 have a higher first ionization energy than aluminum,
wherein the alkaline earth metal is magnesium or calcium,
wherein the element belonging to period 3, 4 or 5 is scandium, titanium, yttrium or niobium,
wherein the alkaline earth metal, and the element belonging to period 3, 4 or 5 are a combination of Mg—Sc, Mg—Ti, Mg—Y, Ca—Sc, Ca—Y or Ca—Zr,
wherein an electronegativity difference between the alkaline earth metal and the element belonging to period 3, 4 or 5 is 0 or more and 0.6 or less,
wherein the total content of the alkaline earth metals and the elements belonging to period 3, 4 or 5 in the alumina ceramic is 0.05 wt % or more and 1 wt % or less based on the content of the alumina,
wherein a ratio (x/y) of the grain boundary area (x) to the grain area (y) in the alumina ceramic is 0.0001 to 0.0005,
wherein the density of the alumina ceramic is 3.8 g/cm3 or more and 4.0 g/cm3 or less, and
wherein the secondary electron emission coefficient of the alumina ceramic is 5.0 or less.