Improvement of Adhesion of Diamond Coatings to WC(CO) Tool Substrates
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hydrogen at the surface of the specimen. Diamond films were grown at substrate temperature of 900'C, 20 Torr ambient, and a gas mixture ratio of
CH
4
:H 2 = 0.5:
2 jm Continuous diamond
2 g mII
100.
Deposition of diamond was TiC carried out for 2 hours to 20 gim obtain a discontinuous first Discontinuous diamond layer with grain /YI diamond size 0.5 to 1 gim. TiC or TiN film was ablated from a E WC(Co) TiC or TiN target, 88 gm respectively, by using pulsed KrF laser beam (wavelength 248 nm, pulse Fig. 1. Digram of two dimensional model of the duration 25 ns) at a pulse TiC composite diamond coating on WC repetition rate of 15 Hz. The laser energy density was optimized to avoid particulate formation in the plume during laser ablation from the target. The substrates were kept at 650 0 C during laser ablation. The TiC or TiN films were deposited for 40,000 pulses. Before deposition of the top continuous diamond layer, the interposing film on the first diamond layer was polished to expose the crystallites in the first diamond layer on the surface, and diamond suspension (
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