Patent ID: 7820308

Claim:
A polycrystalline α-Al 2 O 3 thin film deposited on a base metal for cutting tools or wear-resistant tools by high temperature-chemical vapor deposition, in which the ratio of TC (104) (denoting the texture coefficient of the (104) crystal plane) to TC (012) (denoting the texture coefficient of the (012) crystal plane) in the α-Al 2 O 3 thin film is more than 1.3, the texture coefficient being defined by the following equation: TC ⁡ ( hkl ) = I ⁡ ( hkl ) I 0 ⁡ ( hkl ) ⁢ { 1 n ⁢ ∑ I ⁡ ( hkl ) I 0 ⁡ ( hkl ) } - 1 wherein I(hkl) denotes the diffraction intensity of crystal planes, I 0 (hkl) denotes the standard diffraction intensity of ASTM standard powder diffraction data, n denotes the number of crystal planes used for calculation, and crystal planes (hkl) used are (012), (104), (110), (113), (024), (116), (124) and (030), and wherein the α-Al 2 O 3 thin film is deposited on a thin film of TiAlvBwCxNyOz (v+w+x+y+z=1, x, y≧0; v>0; w>0; z>0), and wherein BC1 3 is used in an amount of 0.1-0.4 vol% in the deposition of the TiAlvBwCxNyOz (v+w+x+y+z=1, x, y≧0; v>0; w>0; z>0) thin film.