Influence of hydrogen content on mechanical properties of ultrananocrystalline diamond films
The influence of the grain size on the development of the morphology of ultrananocrystalline diamond (UNCD) films and their mechanical properties have been investigated by variation of hydrogen content from 5％ to 20％ in the deposition atmosphere. Silicon-based UNCD films were prepared by Microwave Plasma Chemistry Vapor deposition method using argon-rich CH4/H2/Ar plasmas. Their morphology and topography have been characterized by scanning electron microscopy (SEM) and Surface Profilometer. The influences of the hydrogen concentration on the mechanical properties of the deposited UNCD films are investigated by using nano-indentation and nano-scratch tests. It was found that the grain size, growth rate and surface roughness are increased with the increase of the hydrogen concentration. This changes the morphology of the films from granular to needle-like clusters. It also can be seen that the elastic modulus is increased with the addition of hydrogen; the hardness increased monotonically from 5％ to 15％ hydrogen, then decreased for 20％ hydrogen with the maximum at 15％ hydrogen; and the elastic recovery is 72-78％. Hardness and toughness are all decisive for protecting nature of the coatings. The scratch tests proved a strong adhesion of the UNCD coatings and their protective effect on silicon substrates. The hydrogen has significant influence on the mechanical properties. Detailed experimental results and mechanisms for UNCD film deposition in argon-rich plasma are discussed. The deposited highly smooth UNCD film is also expected to be applicable in medical implants, surface acoustic wave (SAW) devices and micro-electromechanical systems (MEMS).
ultrananocrystalline diamond films adhesion mechanical property
Liu Jie Hei Li-Fu Chen Guang-Chao Li Cheng-Ming Song Jian-Hua Lu Fan-Xiu
School of Materials Science and Engineering, University of Science and Technology Beijing, 100083, B College of Materials Science and Opto-electronic Technology, Graduate University of Chinese Academy
国际会议
北京
英文
762-767
2012-10-23（万方平台首次上网日期，不代表论文的发表时间）