Zheng Liu Liangxian Chen Chengming Li Lifu Hei Jianhua Song Guangchao Chen
材料科学技术（英）
Thermal stress in large area free-standing diamond films was remarkable during the post-deposition cooling of direct current (DC) arc plasma jet chemical vapor deposition (CVD) process. In this research, the stress release caused by delamination of Cr interlayer was of great importance to ensure the integrity of free-standing diamond film. The effects of Cr interlayer on Mo substrate, namely composite substrate, on thermal stress were investigated. Thermo-mechanical coupling analysis of the thermal stress was applied by finite element analysis (FEA) using ANSYS code. It was found that the interlayer could be destroyed first by the large thermal stress, and then the stress could be released and the probability of diamond film crack initiation would be reduced. The stress concentration at the bent edge of diamond film was also discussed. In addition, diamond films deposited on Mo substrates with and without Cr interlayer were prepared by DC arc plasma jet CVD system and experimental measurements were used to characterize these films. It was found that composite substrate could be an effective method of growing free-standing crack-free diamond films by DC arc plasma jet CVD system when there is no special requirement to the film strength.
关键词:
CVD diamond film
,
Cr interlayer
,
Thermal stress
,
Finite element analysis
刘学杰
,
魏怀
,
任元
,
陆峰
,
张素慧
,
银永杰
材料工程
doi:10.3969/j.issn.1001-4381.2014.04.008
采用基于密度泛函理论的第一性原理方法研究CVD金刚石薄膜(001)表面的生长机理.计算清洁金刚石表面和氢(H)终止金刚石表面的构型.考察H原子和活性基团(C,CH,CH2和CH3)在清洁重构金刚石表面及在单层H终止金刚石表面上的吸附演变.结果表明:清洁金刚石表面发生了对称二聚体重构,H原子终止金刚石表面稳定了金刚石结构;基团在金刚石(001)表面吸附演变过程中,H原子起到激活石墨和萃取表面H原子产生活性位的作用;CH2基团比CH3基团能够更好地提高CVD金刚石薄膜的生长率,是薄膜生长过程中最有效基团;CH基团阻碍了薄膜的生长.
关键词:
第一性原理
,
CVD金刚石薄膜
,
基团
,
生长机理
,
吸附演变
吴小军
,
左敦稳
,
徐锋
,
王珉
,
何家源
,
袁佳晶
硅酸盐通报
化学气相沉积金刚石膜是聚优异力学、电学、热学性能于一体的材料.金刚石激光打孔过程中存在特有的石墨化现象使得其温度场的分布有别于其他材料,因而,开展CVD金刚石膜激光打孔温度场研究对于理解热加工机理和进行参数优化具有重要的指导意义.本文首先建立了考虑金刚石石墨化过程的激光打孔热力学模型,根据有限元模型开展对CVD金刚石膜激光打孔有限元仿真研究,得到激光打孔温度场和金刚石石墨化的分布规律,并讨论激光能量、脉冲宽度、重复频率对单个脉冲去除量和石墨化程度的影响.仿真结果表明:单个脉冲平均去除量和石墨化程度均随着激光能量、脉冲宽度、重复频率的增加而增加,但激光能量的影响最为显著;当激光能量取0.5～1.6 J,脉冲宽度取300～800 ns,重复频率取30～60 Hz时既可以得到很高的加工效率同时又可以获得热影响区域较小的加工效果.
关键词:
CVD金刚石膜
,
调Q Nd:YAG激光
,
打孔
,
温度场
,
有限元
段萌
,
张运强
,
潘国庆
,
朱瑞华
,
魏俊俊
,
陈良贤
,
李成明
表面技术
doi:10.16490/j.cnki.issn.1001-3660.2017.06.043
目的 通过分析CVD金刚石膜与几种常用红外光学窗口材料在砂蚀过程中形貌特征以及红外透过率的变化规律,获得CVD金刚石膜在砂蚀过程中的材料去除机制及抗砂蚀性能的关键因素.方法 采用喷射式冲蚀磨损系统,对CVD金刚石膜及其他几种常见红外光学材料进行砂蚀性能测试.通过扫描电子显微镜对材料冲蚀后表面形貌进行观察,电子天平测量红外材料砂蚀率.采用红外光谱仪对砂蚀前后红外光学材料进行测量,评价其冲蚀前后的红外性能变化.结果 CVD金刚石膜抗砂蚀能力远高于Ge、ZnS、MgF2以及石英玻璃.在设定测试条件下,仅经过6 s冲蚀,除CVD金刚石膜外,其余光学材料的红外透过性能下降40%~60%.而CVD金刚石经受240 min的相同条件冲蚀,其红外透过率仅下降9.5%,显示出极佳的抗砂蚀能力.结论 CVD金刚石膜的冲蚀过程主要是微裂纹形成及扩张连接导致材料流失.其他材料的冲蚀过程既有裂纹扩展,也有反复的切削、犁削,而后者是这些材料被冲蚀的主要原因.
关键词:
CVD金刚石膜
,
红外窗口
,
砂蚀
,
冲蚀机制
