不同负偏压下磁控溅射纳米TiAlN薄膜的微观结构与耐蚀性能

Microstructure and Corrosion Resistance of Nano TiAlN Coatings Prepared by Magnetron Sputtering Under Different Negative Bias

目前在AZ31镁合金表面利用磁控溅射法制备TiAlN薄膜的研究不多,且未针对负偏压的变化研究Al原子掺杂后薄膜结构及耐腐蚀性能的变化情况。选择射频电源,利用磁控溅射(Magnetron sputtering,MS)方法在AZ31上制备了防腐蚀性能良好的纳米TiAlN薄膜。分别采用X射线衍射仪(XRD)、透射电镜(TEM)和扫描电镜(SEM)测试观察了薄膜的微观特征,借助电化学工作站测试了薄膜在3.5%NaCl溶液中的极化曲线和交流阻抗谱来表征薄膜的耐腐蚀性能。结果表明:基体施加的负偏压大小对薄膜的结晶和生长有较大的影响,膜层主要由TiAlN、AlN和TiN 3相组成,高分辨像和选区电子衍射显示薄膜为细小的多晶结构,3组负偏压下的平均晶粒尺寸分别为35.76,41.22,38.95 nm;薄膜具有较好的耐腐蚀性,腐蚀电位从基体的-1.545 V提高到-1.070 V,电流密度下降了2个数量级,交流阻抗的Nyquist谱和Bode-|Z|谱显示负偏压为45 V的薄膜耐腐蚀性能最好。

Nano-sized TiAlN coatings with excellent corrosion resistance were prepared by magnetron sputtering on AZ31 alloy. XRD,TEM and SEM were employed to study the microstructure of the coatings,and the electrochemical station was employed to evaluate the corrosion resistance of coatings in 3.5% NaCl solution by polarization curves and electrochemical impedance spectrum. Results showed that the growth and crystallization of films were greatly affected by substrate negative bias. The coatings were mainly composed of three kinds of phase containing AlN,TiN and TiAlN. High-resolution TEM images and SEAD images revealed the structure of film was small polycrystalline,and the average grain sizes of coating under the three groups negative bias were 35.76 nm,41.22 nm and 38.95 nm. Moreover,all coatings had good corrosion resistance,and the corrosion potential reduced from-1.545 V of AZ31 to-1.070 V,as well as the current density decreased by two orders of magnitude. Furthermore,Nyquist diagrams and Bode figure indicated that the coating prepared under a negative bias of 45 V possessed the best corrosion resistance.