基体负偏压对类金刚石涂层结构和性能的影响

Influences of Substrate Negative Bias Voltage on Microstructure and Performance of DLC Coatings

采用直流等离子体增强化学气相沉积技术(DC-PECVD),通过控制基体负偏压的变化在YG8硬质合金基体上制备一系列类金刚石涂层。选用扫描电子显微镜、原子力显微镜、拉曼光谱、X射线光电子能谱、粗糙度仪对涂层形貌和结构进行表征测试。同时,利用显微硬度计、划痕测试仪系统地分析涂层的显微硬度和界面结合性能。结果表明:随着负偏压增大,涂层表面形貌逐渐平整光滑、致密,颗粒尺寸减小及数量降低。拉曼光谱表明,涂层具有典型的类金刚石结构,涂层中sp3键含量呈先增大后减小趋势,最大值约67.9%出现在负偏压为1000V左右,负偏压过大导致sp3键含量降低。显微硬度随负偏压变化规律与sp3键基本相符,sp3键含量决定显微硬度值大小。负偏压过大对吸附离子产生反溅射作用导致涂层厚度减小。当负偏压为1100V时,涂层与基体间的界面结合性能最优。

A series of diamond-like-carbon coatings（DLC）were deposited on top of YG8 cemented carbides by direct current plasma enhanced chemical vapor deposition（DC-PECVD）in different substrate negative bias voltage.Scanning electron microscopy,atomic force microscopy,roughness tester,micro-hardness tester,scratch tester,Raman spectroscopy,X-ray photoelectron spectroscopy were used to study the composition,surface morphology,micro-hardness and interfacial adhesion performance of the DLC coatings.The results show that the coatings＇ surface morphology gradually becomes smooth and dense with the increasing of the substrate negative bias voltage.Meanwhile,the number and size of particles decrease.The DLC coatings exhibit typical diamond-like characteristics from Raman spectroscopy.The fraction belonging to sp3 valence bond is approach to a maximum value at 1000 Vand then decreases with the increase of the substrate negative bias voltage.The maximum value of the sp3 valence bond is determined to be about 67.9%.Micro-hardness varying pattern is consistent with sp3 content change low,sp3 content determines the micro-hardness of the DLC coatings.Ions sputtering could lead to the decrease of the thickness when the substrate negative bias voltage increases excessively.The best adhesive strength is gained among the coatings when the substrate negative bias voltage is near to 1100 V.