Ti/Al过渡层对共掺杂类金刚石薄膜性能的影响

目的研究Ti/Al过渡层对不同溅射电流下的Ti/Al共掺杂DLC薄膜的成分、结构、机械性能和结合力的影响。方法采用线性离子束复合磁控溅射技术在316L基底上沉积含有Ti/Al过渡层的Ti/Al共掺杂DLC薄膜,利用场发射扫描电子显微镜(SEM)、X射线光电子能谱仪(XPS)、高分辨透射电镜(HRTEM)及共聚焦激光拉曼光谱仪分析了薄膜的界面形貌及键态结构。采用辉光放电光谱仪对样品成分进行深度分析,纳米压痕仪测量薄膜硬度及弹性模量,划痕测试系统测量膜基结合力,残余应力仪测量薄膜内应力。结果与未添加过渡层相比,添加Ti/Al过渡层对薄膜的结构和机械性能影响较小,且均在溅射电流为2.5 A时有最优的机械性能;然而,溅射电流为2.5 A时,添加过渡层使结合力从54.5 N提高到了67.2 N,提高了19%,残余应力从1.28 GPa降低到了0.25 GPa,降低了80%。结论 Ti/Al过渡层可缓解因DLC薄膜和基体的晶格匹配差异和膨胀系数不同而导致的高界面应力。在薄膜与基底界面,过渡层呈现典型柱状晶结构,可促进膜基界面间的机械互锁,显著改善薄膜与基体之间的结合力而不损伤其机械性能。

Effect of Ti/Al Transition Layer on Properties of Co-doped Diamond-like Carbon Films

The work aims to investigate the effect of the Ti/Al transition layer on composition, bonding structure, mechanical properties, and adhesive strength of Ti/Al co-doped DLC films (Ti/Al-DLC). Ti/Al-DLC film with Ti/Al transition layer was deposited on 316L substrates by novel linear ion beam source composited with DC magnetron sputtering process. The interface morphologies and steady structuresof the films were analyzed by field emission scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM), and confocal laser Raman spec-troscopy. In-depth composition analysis of the sample was performed by glow discharge spectrometer, and the nano-indentation, scratch tester system, and residual stress meter were used to evaluate the hardness and elastic modulus, adhesive strength, and internal stress, respectively. Compared to the film without transition layer, the film with Ti/Al transition layer was slightly affected in the structure and mechanical properties and the optimal mechanical properties were achieved at the sputtering current of 2.5 A. When the sputtering current was 2.5 A, the addition of a Ti/Al transition layer increased the adhesive strength from 54.5 N to 67.2 N, which increased by 19% compared to the film without transition layer. Moreover, the residual stress decreased from 1.28 GPa to 0.25 GPa, which decreased by 80% significantly. The Ti/Al transition layer can further reduce the difference in lattice strain between the DLC film and the substrate and the high interfacial stress caused by the different expansion coefficients. The typical columnar crystal structure for the transition layer formed between the film and the substrate can promote the mechanical interaction between the film-based interfaces and significantly improve the adhesion between the film and the substrate without damaging the mechanical properties.