【作者】 苏亚东；

【导师】 郑伟涛；

【作者基本信息】 吉林大学 ， 材料物理与化学， 2009， 博士

【摘要】 在过去几十年中,超硬薄膜材料由于在工业方面的广泛运用而得到迅速发展。对薄膜材料的研究也逐渐深入,从最初的一元金刚石薄膜,到二元硬质氮化物/碳化物,再到三元Me-X-N(Me代表过渡金属,X代表非金属,N为氮元素)体系,人们设计、合成出的薄膜材料的性能越来越优异。从只有力学优势的单一性能薄膜到具有光、电、力、热复合优势的多性能薄膜,这些都要求薄膜的微观结构具有较高的可控与可重复性,也对薄膜形成机制的研究提出了更高的要求。本论文立足于前人的研究成果,对三元Me-X-N体系薄膜的结构和性能进行了深入系统的研究,重点关注于薄膜的织构行为、相变机制和力学性能。通过对W-C-N,Nb-C-N及Ti-C-H三种薄膜材料的结构和性能的研究,探寻到具有优异力学性能的α-WC薄膜的低温合成方法;探讨了纳米复合薄膜的织构和相变机制及其与力学性能之间的联系;发现并解释了尺寸效应对薄膜织构行为的影响;提出了与织构相关的纳米复合薄膜的结构演变模型。本论文的研究对薄膜的结构控制、设计思路和合成方法都提供了很好的借鉴作用。更多还原

【Abstract】 During the last decades, much interest has been paid to the investigation the nanocomposite thin films (typical: Me-X-N, Me stands for transition metal and X = Si, B, C, etc.) because of their much better mechanical properties than that of unitary or binary coating. Many studies have been performed to control the mictostructure and improve the mechanical properties of thin films. Base on the previous work in literatures, we focused on the texture, phase transition and mechanical properties of nanocomposite thin films in this thesis.. The main works of this thesis are summarized as follows:In chapter 1, we give a brief introduction to the mechanism of film growth, texture behavior, phase transition and mechanical properties. Furthermore, some unresolved issues in the study of structure and properties for nanocomposites and the objective of this dissertation are given.In chapter 2, we introduce the basic concepts and progress of the experimental method used in this work in detail.In chapter 3, we have successfully synthesizedα-WC at a relatively low temperature using direct current reactive magnetron sputtering, and observe a phase transition fromβ-WC toα-WC in the film by increasing N dopant concentration. We find that N content has a significant influence on the intrinsic stress, preferred orientation, phase structure, and hardness for films.In chapter 4, We deposit ternary WCxNy thin films on Si(100) substrates at 500℃using direct current (DC) reactive magnetron sputtering in a mixture of CH4/N2/Ar discharge, and the effects of both bias voltage and annealing on the intrinsic stress, preferred orientation and phase transition for the obtained films have been explored. From the experimentally results, we have found that the substrate voltage bias and annealing have a significant influence on the structure and mechanical properties of the obtained films.In chapter 5, size-effect on the texture behavior has been demonstrated and discussed for TiC/α-C:H nanocomposite films. The texture of film is found to be significantly affected by the grain size, and the size-dependence correlation of texture behavior is discussed by thermodynamic calculations. The results show that the size-dependent Gibbs free energies are likely to be a key factor that controls the texture development in thin films if the grain sizes of films are sufficient small.In chapter 6, the microstructure behavior and texture evolution of nanocomposite films have been explored for NbCxNy films. The relationship between microstructure change and texture evolution have been built in this thesis. Furthermore, the mechanical properties of NbCxNy films including stress and hardness have also been discussed.In conclusion, the microstructure and mechanical properties have been systemically investigated by means for W-C-N, Nb-C-N and Ti-C-H system of films. The results of this thesis can be used for reference to designing and synthesizing of high performance nanocomposite films.更多还原