Coated cutting tool and method for making coating layer

A method for making a coating layer on the whole or part of a substrate of a cutting tool, the method comprising:

• depositing a TiN layer on the upper surface of the substrate;
• depositing an MT-TiCN layer which has texture coefficients of TC(311)>1.5 and TC(422)>1.5 and is formed of columnar grains of TiCN deposited on the TiN layer by a chemical vapor deposition method within the range of 800° C. to 950° C.;
• depositing an TiCNO bonding layer on the upper surface of the MT-TiCN layer, and then oxidizing the TICNO bonding layer for a predetermined time using H2, N2, CO, and CO2;
• and
• depositing, on the oxidized TiCNO bonding layer, an α-Al2O3 layer which has a texture coefficient of TC(006)>4 and is formed of columnar grains,
• wherein an HT-TiCN layer does not exist between the MT-TiCN layer and the α-Al2O3 layer, and
• wherein the TC(311), TC(422), and TC(006) are defined according to Harris formula:
• TC
• ⁡
• (
• hkl
• )
• =
• I
• ⁡
• (
• hkl
• )
• I
• 0
• (
• hkl
• )
• [
• 1
• n
• ⁢
• ∑
• n
• =
• 1
• n
• ⁢
• I
• ⁡
• (
• hkl
• )
• I
• 0
• (
• hkl
• )
• ]
• -
• 1
• ,
• wherein I(hkl) above is the reflection or diffraction intensity of the measured (hkl) plane,
• I0(hkl) above is the standard intensity according to PDF of ICDD, and the standard intensity according to the PDF Card No. 42-1489 of ICDD is used to calculate the texture coefficient of the MT-TiCN layer, and the standard intensity according to the PDF Card No. 42-1212 of ICDD is used to calculate the texture coefficient of the α-Al2O3 layer,
• n is the number of reflecting planes used in the calculation of the texture coefficients, and
• the (hkI) reflecting planes used in the calculation of the texture coefficient of the MT-TiCN layer are (111), (200), (220), (311), and (422) and the (hkI) reflecting planes used in the calculation of the texture coefficient of the α-Al2O3 layer are (012), (104), (110), (006), (113), and (116).