氮化铬梯度膜的制备和电化学性能研究

Preparation and Electrochemical Properties of Gradient CrNx Coatings on H13 Steel

摘要:

在H13钢基体上制备了几种成分的CrNx双层膜和梯度膜。使用X光电子能谱(XPS)分析了膜层的成分，使用X射线衍射仪(XRD)分析膜层的主要相结构：同时检测了膜层的硬度与工艺参数的关系。系统地研究了膜层的动电位极化曲线，梯度膜能够明显降低膜层的腐蚀电流密度。使用扫描电子显微镜(SEM)，研究了膜层显微结构和性能之间的关系，并提出了双层膜和梯度膜的结构模型。膜层的主要成分、结构都随着氮气分压而改变。随着氮气分压从0．05Pa提高到2Pa，CrNx膜层中的N／Cr原子比从0．08提高到0．67。氮气分压0．05Pa时，双层膜的成分包括Cr(bcc)和Cr2N(hex)，在分压达到2Pa时，膜层主要成分为CrN(fcc)，在梯度膜中有一个CrN(220)择优取向。相对于CrN／Cr／H13双层膜，梯度薄膜的抗腐蚀性能有明显提高。在双层膜上有较多较深的微孔，而在梯度膜表面比较鲜见。

Abstract:

Chromium nitride (CrN) coatings deposited by physical vapor deposition (PVD) processes have been adopted for wear protection of cutting tools and various metallic components for years. To further improve the electrochemical performances of CrN coatings, duplex CrNx coatings of various stoichimetries and gradient coating were prepared by cathodic arc evaporation. The chemical analysis was carried out by X-ray photoelectron spectroscopy (XPS). The crystallographic structure was investigated by X-ray diffraction (XRD). The composition, structure of the coatings varied as a function of nitrogen pressure. The potentiodynamic polarization was examined by Zahner IM6e electrochemical workstation, and the corrosive surface was detected by scanning electron microscopy (SEM). The results showed that the graded coating had an better electrochemical performance than duplex CrN coating. The relationship of microstructure and properties was studied, and a model of gradient CrN coating was constituted.