纳米金刚石薄膜的制备与应用

FABRICATION AND APPLICATION OF NANOCRYSTALLINE DIAMOND FILMS

采用偏压辅助增强热丝化学气相沉积法(Chemical vapor deposition,CVD),以WC-Co硬质合金为衬底,采用控制沉积参数和添加惰性气体Ar等CVD新工艺,制备性能优良的纳米金刚石薄膜。进一步采用扫描电镜(Scanning electron microscopy,SEM)、原子力显微镜(Atomic force microscopy,AFM)、拉曼光谱(Raman spectros- copy)、X射线衍射(X-ray diffraction,XRD)和高分辨率透射电镜(High-resolution transmission electron microscopy, HR-TEM)分析了薄膜的纳米效应。研究结果表明:纳米涂层仍然是以金刚石结构为主的多晶体,它晶体颗粒较小(20～80 nm),含有较多的晶界和sp^2结构,涂层表面粗糙度R_a≤50 nm,表面平整光滑,有利于研磨抛光。在此基础上,提出纳米金刚石复合涂层制备新技术,开发研制出各种涂层拉拔模具,在实际生产线上进行了应用,取得了显著的效果。

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 spectroscopy, atomic force microscopy （AFM）, high-resolution transmission electron microscopy （HR-TEM） and selected-area electron diffraction （SAED）. The results show that nanocrystalline 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 rim. 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 free-grained nanocrystalline diamond coating. The diamond-coated drawing dies with these composite coatings display excellent performances in the practical application.