Coated cutting tool

A method of preparing a coated cutting tool comprising:

• providing a substrate by ion etching a sintered composite body including cubic boron nitride and a binder phase including TiCyN1-y, wherein 0≤y≤1 to an average depth of at least 200 nm corresponding to an average surface removal of at least 200 nm of the sintered composite body, wherein the binder phase contains impurities of
• aluminium expressed as a net intensity ratio of Al to Ti in the substrate below 0.50 as measured by Energy Dispersive X-ray Analysis (EDX);
• and/or
• tungsten expressed as a net intensity ratio of W to Ti in the substrate below 0.035 as measured by Energy Dispersive X-ray Analysis (EDX);
• and/or
• TiB2 expressed as a ratio of a net peak height of the TiB2 peak to the net peak height of the TiCN peak being less than 0.09 as measured by XRD;
• and/or
• α-alumina expressed as a ratio of a net peak height of a α-alumina peak to a net peak height of a TiCN peak being less than 0.06 as measured by XRD;
• and
• a coating deposited on the substrate, the coating including at least one layer composed of a nitride of one or more elements belonging to group 4, 5 or 6 of the periodic table of elements, or a nitride of Al and/or Si together with one or more elements belonging to group 4, 5 or 6 of the periodic table of elements.