掺杂组元选择、分布及尺度对磁控溅射X-Cr-C非晶碳膜减摩耐热性能影响机制的研究

Benefit from a gradient structure and unique roles of nanocrystallines of Cr dopant, Cr/GLC films could achieve higher than 70N adhesive strengths and quite low COF (coefficient of friction) with a level of about 0.1. Without the 'catalyst effect' and the instability serving in wet circumstance that commonly bothering DLC films, they are considered as a candidate for hard lubricating solid films with a promising perspective. However, due to the highest service temperature of the Cr/GLC films is lower than 300℃, a bottleneck of poor thermal oxidization resistance for their industrial application is also apparent. Many researches on DLC films indicate that, the dominant mechanism for the starting up of low temperature thermal oxidization and turning to failure in DLC films is owing to the formation of volatile COx phase which has a quite low volatilization temperature. It could be improved by retarding the diffusion of C and/or O elements in the films with the aid of adding other doping elements. For the above consideration, this application proposes an idea based on X-Cr-C ternary system to solve the above problems. In this kind of X-Cr-C films, the sophisticated gradient structure will be inherited from the Cr/GLC films. Meanwhile, Cr and X elements will be added into the top working layer as type I & type II dopants, respectively. Similar to the roles in the Cr/GLC films, the former Cr dopant is expected to inherit as much as possible the effects in relieving internal stress, and inducing the sp2 bonding formation. As for the latter dopant X, it's focused on retarding or even blocking the diffusion of C and/or O elements. For the diffusion retarding dopant X, strong carbide formers such as Mo/W and oxide formers such as Al/Si will be selected respectively to perform comparative study. Based on a proposed mixing model suitable for the formation of nano-scale microstructure in multiple component films deposited by multi-target magnetron sputtering, the controlling method for the distribution & scale of the two types of dopants will be established. The influencing mechanism of selection, distribution & nanoscale of the dopant X on lubricating performance and thermal oxidization resistance of magnetron sputtered X-Cr-C amorphous carbon films will be revealed by experimental research and theoretical analysis on the effects of dopant X on mechanical, tribological properties and thermal oxidization behaviors. The results may provide a set of developing theories and practical processes for a novel series of high performance graphite like carbon films with both hard lubricating performance and better thermal oxidization resistance.

受益于梯度结构及掺杂Cr纳米晶的独特作用，Cr/GLC膜结合强度可≥70N、COF≈0.1，且无DLC膜触媒效应和耐湿性差等问题，作为高硬减摩材料前景诱人。但其最高服役温度仅300℃左右，耐热性瓶颈明显。相关研究指出，低挥发温度COx相的形成是其低温启动热氧化进而失效的主要机制，可引入掺杂元素阻滞C、O扩散改善。为此，本申请提出X-Cr-C三元体系，在继承Cr/GLC膜梯度设计基础上，在工作层引入Cr和X作为第I、II类掺杂元素：前者继承缓解内应力、诱导sp2键形成作用；后者阻滞C、O扩散。其中，X分别选用阻滞C、O扩散的强碳/氧化物形成元素Mo、W和Al、Si进行比较研究，并基于多元溅射混合模型，建立两类掺杂相尺度控制方法，系统研究X掺杂相的选择、分布及尺度对X-Cr-C膜力学/摩擦学性能及热氧化行为的影响规律及机制，为开发兼具高硬减摩性及更高服役温度的类石墨碳膜提供理论依据及工艺方法。