Chemical vapor deposition, introduced in the late 1960s, was the first hard tool coating technology. It has advanced from single-layer to current multilayer designs combining TiC, TiN, TiCN and Al_2O_3. Layer sequences and total coating thick-ness are tailored to different metalcutting applications. CVD has been dominant in cemented carbide tools, which tolerate the high deposition temperature of about 1,000 deg C. Physical vapor deposition technology was introduced a decade later with a monolayer TiN coating, using lower deposition temperature (less than 550 deg C). PVD was first proven on HSS tools, and then found acceptance in a narrow application field of interrupted-cutting and sharp-edged carbide tools.
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