CrAlN/WS_2纳米多层膜的微观结构和力学性能研究

Study on microstructure and mechanical properties of CrAlN/WS_2 nanomultilayered films

采用反应磁控溅射工艺在Si基体上沉积了不同调制周期的CrAlN/WS2纳米多层膜,采用X射线衍射仪（XRD）、高分辨透射电子显微镜（HRTEM）、纳米压痕仪和HSR-2M涂层摩擦磨损试验机、扫描电子显微镜（SEM）,研究了调制周期对CrAlN/WS2纳米多层膜微观结构和力学性能的影响。研究结果表明,WS2层厚度低于0.8nm时,六方结构的WS2在CrAlN的模板作用下转变为B1-NaCl型面心立方结构并与CrAlN层发生共格外延生长,使薄膜得到强化,在WS2层厚度为0.8nm时,薄膜硬度和弹性模量达到最大,分别为37.3和341.2GPa。随着WS2层厚度的进一步增加,WS2又转变回六方结构,使薄膜共格外延生长结构破坏,结晶度降低,耐磨性增强,硬度和弹性模量减小。CrAlN/WS2纳米多层膜的摩擦系数均在0.2-0.3之间,远低于单层CrAlN的摩擦系数的0.6,磨损率亦明显减小。获得了综合力学性能优异的CrAlN/WS2纳米多层膜。

CrAlN/WS2 nanomultilayered films with different modulation periods were synthesized on Si sub-strate by reactive magnetron sputtering.The influences of modulation periods on microstructure and mechanical properties were investigated by X-ray diffraction （XRD）,high-resolution transmission electron microscopy （HRTEM）,nano-indentation techniques and coating friction-wear testing machine,scanning electron micro-scope（SEM）.The results indicated that,when WS2 layer thickness was less than 0.8nm,hexagonal-structured WS2 layers were forced to transform to B1-NaCl structure under the template effect of CrAlN layers and grew epitaxially with CrAlN layers,resulting in enhancement of mechanical properties.The maximum hardness and elastic modulus could respectively reach 37.3 and 341.2 GPa when WS2 thickness was 0.8nm.With further in-crease of WS2 layer thickness WS2 layer could not keep fcc structure and transformed to hexagonal-structure, making epitaxial growth structure broken and leading to the decrease of hardness and elastic modulus.The fric-tion coefficient of CrAlN/WS2 nanomultilayered films was 0.2-0.3,much lower than that of monolithic CrAlN film,and the wear rate obviously decrease,suggesting that the insertions of WS2 layers greatly improved the friction and wear resistance of CrAlN/WS2 nanomultilayered films.