|
Abstract: Nanocrystalline diamond films are deposited on Co-cemented carbide substrates using bias-enhanced hot filament chemical vapor deposition(HFCVD) technique by appropriately controlling deposition parameters and Ar addition. The evidence of nanocrystallinity,
smoothness and purity is obtained by characterizing the sample with scanning electron microscopy(SEM), X-ray diffraction(XRD), Raman spectros-copy, atomic force microscopy (AFM), high-resolution trans-mission electron microscopy (HR-TEM) and selected-area electron diffraction (SAED). The results show that nanocrystal-line diamond films consist of nanocrystalline diamond grains with sizes range from 20 to 80 nm and contain a large amount of grain boundaries. Surface roughness is measured at Ra< 50 nm. Smooth diamond films are liable to polishing. A new process was used to deposit composite diamond coatings by a two-step chemical vapor deposition procedure including first the deposition of the rough polycrystalline diamond and then the smooth fine-grained nanocrystalline diamond coating. The dia-mond-coated drawing dies with these composite coatings dis-play excellent performances in the practical application.
Key words: Nanocrystalline diamond films
Cemented tungsten carbide
Surface roughness Composite coatings
CLC No: TG156
国家自然科学基金(50575135)和国家高技术研究发展计划(863计划, 2002AA302613)资助项目. Received 20060311,
received in revised form 20061221
|