Microstructure, mechanical properties, and milling performance of arc-PVD AlTiN-Cu and AlTiN/AlTiN-Cu coatings

Abstract

AlTiN, AlTiN-Cu and AlTiN/AlTiN-Cu coatings were prepared on WC-6%Co substrates by cathode arc evaporation deposition technology. Two kinds of nitrogen pressures were used to deposit both AlTiN-Cu and AlTiN/AlTiN-Cu coatings. Surface and cross-sectional morphologies of films were observed by scanning electron microscopy (SEM). Crystal structure of films was analyzed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Hardness and adhesion of films were measured by nano-indentation and nano-scratch tester. Cutting tests were performed under milling conditions during wet machining of TC4 alloy. The results show that with addition of Cu, more droplets occur on AlTiN coating surface, but the grain size of it is refined, and the hardness decreases but the toughness is improved. Under higher N₂ pressure, the defects on the surface of AlTiN-Cu and AlTiN/AlTiN-Cu coatings diminish, and the hardness of them is enhanced, while the adhesion is reduced. Compared to AlTiN coated cemented carbide tool, the lifetimes of AlTiN-Cu and AlTiN/AlTiN-Cu coated tools under the same N₂ pressure are improved by 11% and 24%, respectively.

摘要

采用阴极弧蒸发沉积技术在WC-6%Co 基体上制备AlTiN、AlTiN-Cu 和AlTiN/AlTiN-Cu 涂层, 采用2 种氮气压力制备 AlTiN-Cu 和AlTiN/AlTiN-Cu 涂层:2.2 Pa 和3.2 Pa。利用扫描电镜观测涂层 的表面形貌和截面形貌,结合X 射线衍射谱和X 射线光电子能谱确定涂层成分和晶体结构,利用纳 米压痕划痕仪测定涂层的硬度和膜基结合力。在相同条件下,进行湿式铣削TC4 试验,对比研究5 种涂层刀具的铣削性能。研究结果表明,添加Cu 后,AlTiN 涂层表面液滴增多,晶粒细化,硬度降 低但耐磨性提高。当N₂ 压力由2.2 Pa 增大到3.2 Pa 时,AlTiN-Cu 和AlTiN/AlTiN-Cu 涂层晶粒尺寸 细化,硬度提高但是膜基结合力下降。在相同N₂ 压力下,AlTiN-Cu 和AlTiN/AlTiN-Cu 涂层刀具铣 削寿命分别较AlTiN 涂层刀具的提高11% 和 24%。