Diamond films for wear protection of hardmetal tools

In order to improve the wear protection of hardmetal cutting tools, polycrystalline diamond coatings with high quality have been produced by the u.s.e.(TM)-process. The strong adhesion of the diamond coating by mechanical clamping is generated by the pretreatment of the WC-6 wt% Co substrate surface. The wear behaviour of micro- and nanostructured crystalline diamond films was examined with cavitation test. The influence of diamond film structure (morphology, crystal size and orientation, roughness) as well as coating thickness and adhesion at the interface on the wear mechanisms was investigated. Regarding lifetime and performance of the diamond-coated tools, the nanocrystalline diamond structure shows a very high potential in industrial machining applications. The nanostructured diamond with its smooth surface surpasses the microstructured diamond as coating material for suitable substrates with even complex pre-shaped geometries. The extraordinary wear resistance for thin (3 mum) smooth films with optimised layer strength and fracture toughness could be exceeded by further increasing the coating thickness. (C) 2002 Elsevier Science Ltd. All rights reserved.