Cutting applications of DLC, hard carbon and diamond films

Due to their high hardness and low friction coefficient, diamond-like carbon (DLC), amorphous hard carbon (HC), and diamond coatings have great potential for dry cutting operations. The main differences between these coatings can be found in their hardness (respectively 2500, 5000-8000 and 10000 HV), morphology (DLC and HC: amorphous and diamond: crystalline) and their thermal stability (DLC, 250 degrees C, HC: 600 degrees C and diamond: 700 degrees C). DLC, HC and CVD diamond-coated hard inserts and end-mills were evaluated for the dry turning of Al-SIC metal matrix composites and for the dry milling of Al malleable alloys, where turning of Al-SiC metal matrix composites and for the dry milling of Al malleable alloys, where hard carbon coatings are known to have good anti-sticking properties with respect to aluminium. In cases where the DLC and HC coatings did not improve the tool lifetime in any of our proofs, CVD diamond-coated tools were found to be a good alternative to PCD tipped tools for the dry machining of Al-SiC metal matrix composites. The coatings were characterized by Raman spectroscopy and Vickers hardness measurements. The wear analyses were performed using scanning electron microscopy (SEM). (C) 1999 Elsevier Science S.A. All rights reserved.