Patent ID: 7531214

Claim:
Method of depositing a crystalline α-Al 2 O 3 -layer onto a cutting tool insert by chemical vapor deposition comprising the following steps: depositing a, from about 0.1 to about 1.5 μm, layer of TiC x N y O z where x+y+z>=1 and z>0; treating said layer at from about 625 to about 1000° C. in a gas mixture containing from about 0.5 to about 3 vol-% O 2 for a short period of time from about 0.5 to about 4 min; and depositing said Al 2 O 3 -layer by bringing said treated layer into contact with a gas mixture containing from about 2 to about 10 vol-% of AlCl 3 , from about 16 to about 40 vol-% of CO 2 , in H 2 and from about 0.8 to about 2 vol-% of a sulphur-containing agent at a process pressure of from about 40 to about 300 mbar and a temperature of from about 625 to about 800° C.