Patent ID: 7955722
Filing Date: 2011-06-07
Classification: C23C,Y10T

Abstract:
1. A protective alumina film mainly comprising alumina in the α-crystal structure, wherein the protective alumina film is formed on an oxidation layer present on a surface of a base material or of an undercoat film previously formed on the base material, the protective alumina film comprises one or more regions comprising additionally an element other than aluminum, the element other than aluminum being at least one of Cr and Fe capable of forming an oxide thereof, the region is formed along the planes in the direction almost perpendicular to the thickness direction of the protective film, and the region is present intermittently in the thickness direction inside the protective film to form a layer between alumina layers mainly in the α-crystal structure, wherein the formed layers comprising an additional element other than aluminum have a total thickness of 10% or less with respect to a thickness of the protective film, and a thickness of each of the alumina layers is 0.5 μm or less.