ARC-PVD-COATING OF CEMENTED CARBIDES AND ANALYSIS OF THEIR FUNCTIONAL-BEHAVIOR IN INTERRUPTED CUT MACHINING

Interrupted machining of quenched and tempered steel demands the application of tools with high resistance against mechanically and tribologically induced wear. These demands can not be fully satisfied by uncoated carbides. Also CVD-coatings give only some improvement due to a certain embrittlement of the substrate during the coating process. PVD-coatings deposited at low temperatures without affection of the substrate lower the influence of the relevant wear mechanisms preferably at moderate cutting speeds. The combination of tough substrates with structural and compositional optimized coatings results in a multiplication of tool life within the whole range of low and medium cutting speeds. Coatings with homogenious structure, compressive residual stresses and high content of metalloides ensure excellent resistance against wear. Titanium-carbonitride deposited on carbide was found to be superiour compared with other carbonitride, nitride and carbide coatings within the system Ti-Zr-C-N due to excellent tribological properties. It was optimal suited for the interrupted cut application.