Patent ID: 7695764

Claim:
A method of coating a substrate with an α-Al 2 O 3 layer wherein the α-Al 2 O 3 layer is composed of columnar α-Al 2 O 3 grains with a texture coefficient TC(116) greater than about 1.8 comprising: depositing a (Ti,Al)(C,O,N) bonding layer on said substrate to provide a nucleation surface for said α-Al 2 O 3 layer, subjecting said nucleation surface to a modification treatment including a pulse treatment with a mixture of TiCl 4 , AlCl 3 and H 2 , a purge with a neutral gas and an oxidizing pulse of a gas mixture including N 2 and CO 2 , repeating the modification treatment, and depositing α-Al 2 O 3 having a texture coefficient TC(116) greater than about 1.8 at a temperature of from about 750 to about 1000° C.