AlTiN,AlTiN-Cu和AlTiN/AlTiN-Cu涂层的组织结构与耐腐蚀性能

Microstructure and corrosion resistance of AlTiN, AlTiN-Cu and AlTiN/AlTiN-Cu coatings

采用阴极弧蒸发沉积设备在WC-6%Co(质量分数)基体上制备AlTiN,AlTiN-Cu和AlTiN/AlTiN-Cu涂层。采用扫描电子显微镜(SEM)观察涂层表面形貌和截面形貌,利用X线衍射仪(XRD)检测涂层的相结构。采用Tafel极化曲线和电化学阻抗谱(EIS)方法,研究这3种涂层硬质合金在质量分数为3.5%的NaCl溶液中的电化学行为,比较这3种涂层的耐腐蚀性能。研究结果表明:Cu的加入使AlTiN涂层表面液滴增多,但减小晶粒粒度,使涂层结构更加致密,孔隙率减小;与硬质合金基体相比,AlTiN,AlTiN-Cu和AlTiN/AlTiN-Cu涂层硬质合金的自腐蚀电流(icorr)分别降低40%,80%和93%,电荷转移电阻(R_(ct))分别提高2.91,3.72和7.85倍,耐腐蚀性能大大提高;3种涂层耐腐蚀能力从强到弱依次为AlTiN/AlTiN-Cu,AlTiN-Cu和AlTiN。

AlTiN, AlTiN-Cu and AlTiN/ AlTiN-Cu coatings were produced by cathode arc evaporation deposition equipment on WC-6% Co substrates. Surface and cross-sectional morphologies of coatings were observed by SEM. Phase structures of coatings were studied by XRD. The corrosion resistances of coatings were investigated using Tafel polarization curve and electrochemical impedance spectroscopy in 3.5% NaCl solution. The results show that the amount of droplets on AlTiN coating surface increases with the increase of addition of Cu, but the grain size of it is refined, and the structure is more compacted, and the porosity decreases. Compared with cemented carbide substrate, the corrosion current densities （icorr） of AlTiN, AlTiN-Cu and AlTiN/AlTiN-Cu coated cemented carbides reduce by 40%,80% and 93%, respectively, and the charge transfer resistances（Rct） of AlTiN, AlTiN-Cu and AlTiN/AlTiN-Cu coated cemented carbides increase by 2.91,3.72 and 7.85 times, respectively. Obviously, corrosion resistances of coated cemented carbides are greatly improved. The corrosion resistant abilities of three kinds of coatings decreases from large to small in following order： AlTiN/AlTiN-Cu, AlTiN-Cu and AlTN.