精密模压模具用类金刚石薄膜表面失效与恢复

Surface Failure and Restore of Diamond-Like Carbon Films for Precision Molding Moldes

为了研究精密模压模具用类金刚石(DLC)薄膜的表面失效过程,探索恢复失效薄膜表面性能的方法,用磁过滤阴极电弧设备在硬质合金模具上制备无氢类金刚石ta-C薄膜,在精密模压机上使用该模具对玻璃开展模压。通过拉曼光谱检测经历不同次数模压薄膜结构变化情况,使用维氏硬度计、白光干涉仪检测模压前和多轮模压后ta-C薄膜的表面状态差异,从而评价薄膜在精密模压过程中的失效方式。结果表明:随着模压次数的增加,ta-C薄膜拉曼特征峰比值I_(D)/I_(G)从0.66上升到超过2.67,发生四面体配位sp^(3)向三配位键合结构sp^(2)的相转变。ta-C薄膜的硬度经模压后下降了15.5%,表面粗糙度由0.6 nm增大到25.8 nm,且膜层的整体均匀性下降。薄膜失效异常位置分析揭示了相转变主要发生在薄膜外表面,薄膜内部结构在模压过程中仍保持相对稳定,通过氧离子刻蚀可以使模压后的ta-C薄膜表面状态恢复。

In order to study the surface failure process of diamond-like carbon films used in precision molding molds and to explore methods for restoring the surace properties of failed films,a hydrogen-free diamond-like carbon(ta-C)film was prepared on a hard alloy mold using magnetic filtered cathode arc equipment,the mold was used to mold glass in a precision molding press.The structural changes of the film undergoing diferent times of molding were detected by Raman spectrscopy,and the differences in the surace state of ta-C films before molding and alter multiple rounds of molding were detected by using a Vickers hardness tester and white light inteferometer,so as to evaluate the failure mode of the films in the precision molding process.The results showed that as the number of molding cycles inereased,the Raman characteristic peak raio I_(D)/I_(G)of the ta-C film inereased from 0.66 to 2.67,indicating a phase transition from tetrahedral sp^(3)to triple coorlina tion bonding sp^(2).Afer molding,the hariness of the ta-C film decreased by 15.596,while the surace roughness inereased from 0.6 nm to 25.8 nm,'The overal unifomity of the film aver decreased,Analysis of the localion of film failure anomalies revealed that the phase trausiio mail occumed on the outer surace of the film,and the inner structure of the film remained relatively stable during the molling process.and the surface state of the molded ta-C film could be restored by oxygen ion etching.