Development of an industrialised DLC duplex treatment process

In the framework of the EC Brite project ‘IPEC’, a DLC duplex treatment process (plasma nitriding followed by plasma deposition of diamond-like carbon) was developed and scaled up to large reactor dimensions (2 m3 volume). A basic feature of the process is the use of a low frequency pulsed dc power generator to control plasma conditions. The duplex process was optimised with respect to coating performance (adhesion, wear and friction behaviour, defects) and treatment time. The coated samples were characterised with the following techniques: nano-indentation (hardness), ball-on-disc (wear and friction), scratch test (adhesion), scanning electron microscopy and Raman spectroscopy (microstructure) and calo (thickness) tests. This paper presents the results of these investigations.