类金刚石碳膜在纳米划擦过程中的弹-塑性变形及断裂机制分析

ELASTIC-PLASTIC DEFORMATION AND FRACTURE MECHANISM ANALYSIS OF DIAMOND-LIKE CARBON FILMS DURING NANOSCRATCHING

利用纳米划痕仪研究了Ｔｉ合金表面类金刚石薄膜在划擦过程中的弹塑性变形和裂纹形成微观机制．结果表明：试样在划擦过程经历了薄膜变形、薄膜与基体共同变形和薄膜剥离３个阶段，对应的Ｐ—Ｄ曲线分别在划擦前后无变化、出现分离和急剧变化．在第三阶段中塑性变形量超过弹性变形量，在薄膜内部产生裂纹，薄膜与基体变形恢复不同步，薄膜发生剥落．因此，提高薄膜划擦抗力的有效途径是增强膜基的结合强度和提高薄膜的断裂韧性．

The nanoscrach properties of diamond-like carbon (DLC) films prepared on Ti alloy substrate with rf PECVD were evaluated using a Nano Indenter XP system with the attachments of lateral force measurement (LFM) and their elastic-plastic deformation and mechanism of cracks formation were also analysed during scratching. It was concluded that three processes containing deformation of films, together deforming of films and substrate, and pulling-off of films successively occur with the increase of load during scratching, corresponding to nearly overlaying, separating and abruptly changing of the P-D curves. During the third regime, plastic deformation exceeded elastic part, films were delaminated from the substrate, which may be attributed to combining effect of cracks in the film and the entire pulling-off between the film and the substrate due to asynchronous recovery of the films and the substrate. Therefore, it is important to enhance bond strength and fracture toughness of films.