硼碳氮薄膜的脉冲激光沉积、键结构演变与力学性能

发布时间：2018-03-26 15:01

本文选题：B-C-N薄膜　切入点：脉冲激光沉积　出处：《武汉理工大学》2015年硕士论文

【摘要】：硼碳氮(B-C-N)三元化合物兼具立方氮化硼与金刚石的优良特性,作为一类超硬结构材料,在防护涂层、切削工具等工程领域具有广泛而重要的应用。特定键结构是B-C-N薄膜获得优异力学性能的前提,而现有研究却很少涉及沉积过程中B-C-N薄膜的键结构演变问题。为此,本文采用脉冲激光沉积技术制备B-C-N薄膜,重点研究其键结构和力学性能随沉积工艺(氮气压力、衬底温度、激光能量密度)的演变规律,以期通过建立键结构和力学性能之间的相互关系实现对B-C-N薄膜力学性能的优化。通过调整沉积工艺,分别在不同氮气压力(2.5~5.0 Pa)、衬底温度(RT~600?C)和激光能量密度(1.0~3.0 J/cm2)条件下制备出B-C-N薄膜。利用红外光谱和X射线光电子能谱对薄膜结构进行分析,结果表明薄膜中均含有B-N、B-C、C-N和C=N等不同结合键,说明形成了B-C-N三元化合物,得到的薄膜为原子级杂化。随着氮气压力的增大,B-C-N薄膜的沉积速率不断增大,粗糙度先减小后增大,同时N含量增加,B含量先增加后减小,而C含量先减小后增加。此外,薄膜键结构也发生相应演变:当氮气压力从2.5 Pa增大到3.5 Pa时,键结构由sp2杂化的B-N和C=N键向B-C键和sp3杂化的C-N键演变;由3.5 Pa继续增大到5.0 Pa时,薄膜的键结构又发生由B-C和sp3杂化的C-N键向sp2杂化的B-N和C=N键逆向演变。随着衬底温度的升高,B-C-N薄膜的沉积速率和表面粗糙度均不断减小,同时C和N含量逐渐降低而B含量增大,而且键结构也发生相应演变:当衬底温度从室温升高到400?C时,键结构从sp2杂化的B-N和C=N键向B-C键和sp3杂化的C-N键演变;从400?C继续升高到600?C时,又由B-C和sp3杂化的C-N键向sp2杂化的B-N和C=N键逆向演变。随着激光能量密度的增大,B-C-N薄膜的沉积速率不断增大,表面粗糙度先增大后减少,同时B和N的含量逐渐增加而C含量则不断降低,而且键结构逐渐由sp2杂化的B-N和C=N键向B-C键和sp3杂化的C-N键演变。在不同脉冲激光沉积条件下制备的B-C-N薄膜,其硬度和弹性模量的变化范围分别为7.5~33.7 GPa和128~256 GPa,这与沉积过程中薄膜键结构和键含量的演变规律相一致:高含量的B-C键和sp3杂化的C-N键有利于提高薄膜硬度和弹性模量,而高含量sp2杂化的B-N和C=N键则会劣化薄膜的力学性能。
[Abstract]:Boron carbon nitride B-C-N) ternary compound has the excellent properties of cubic boron nitride and diamond, as a kind of superhard structure material, in the protective coating, Cutting tools and other engineering fields have a wide range of important applications. Specific bond structure is the prerequisite for obtaining excellent mechanical properties of B-C-N thin films, while the existing research rarely involves the evolution of bond structure of B-C-N thin films during deposition. In this paper, B-C-N thin films were prepared by pulsed laser deposition. The evolution of bond structure and mechanical properties with the deposition process (nitrogen pressure, substrate temperature, laser energy density) was studied. By establishing the relationship between bond structure and mechanical properties, the mechanical properties of B-C-N films can be optimized. The structure of B-C-N thin films was analyzed by infrared spectroscopy and X-ray photoelectron spectroscopy. The results show that the films contain different binding bonds, such as B-N B-Con C-N and Con N, indicating the formation of ternary compounds of B-C-N. With the increase of nitrogen pressure, the deposition rate of B-C-N films increases, the roughness decreases first and then increases, while the N content increases first and then decreases, while the C content decreases first and then increases. When the nitrogen pressure increased from 2.5 Pa to 3.5 Pa, the bond structure changed from B-N and Con N bonds of sp2 hybrid to B-C bond and C-N bond of sp3 hybrid, and increased from 3.5 Pa to 5.0 Pa. The bond structure of the films changed from B-C and sp3 hybrid C-N bonds to sp2 hybrid B-N and Con N bonds. The deposition rate and surface roughness of B-C-N films decreased with the increase of substrate temperature. At the same time, the content of C and N decreases gradually, while the content of B increases, and the bond structure evolves accordingly: when the substrate temperature increases from room temperature to 400? At C, the bond structure evolves from B-N and Con N bonds of sp2 hybrid to B-C bond and C-N bond from sp3 hybrid bond, from 400? C continues to rise to 600? With the increase of laser energy density, the deposition rate of B-C-N films increases and the surface roughness increases first and then decreases with the increase of laser energy density. At the same time, the contents of B and N increased and the content of C decreased, and the bond structure gradually changed from B-N and Con N bonds of sp2 hybrid to C-N bonds of B-C bond and sp3 hybrid. B-C-N thin films were prepared under different pulsed laser deposition conditions. The variation range of hardness and modulus of elasticity is 7.5g / 33.7 GPa and 128256GParespectively, which is consistent with the evolution of bond structure and bond content during deposition: high content B-C bond and sp3 hybrid C-N bond can improve the hardness and elastic modulus of the film. The mechanical properties of the films were degraded by B-N and Con N bonds with high content of sp2 hybrid.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.2

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