钛合金表面DLC薄膜的制备及其承载特性研究

发布时间：2018-04-03 03:36

  本文选题：TC4合金　切入点：多层DLC薄膜　出处：《重庆理工大学》2017年硕士论文

【摘要】：本文以TC4合金为研究对象,首先,利用非平衡磁控溅射技术制备了具有Cr、Ti和Si过渡层的类金刚石(Diamond-like carbon,DLC)薄膜,探究了过渡层对DLC薄膜结构和性能的影响,考察了反应磁控溅射参数(基底偏压、沉积气压、甲烷流量和溅射功率)与DLC薄膜结构、力学和摩擦学性能的关联;其次,以不同基底偏压下制备的DLC薄膜为基础,利用有限元方法模拟了不同膜层顺序(偏压调控的软硬薄膜)、调制周期、调制比例对多层DLC薄膜承载能力的影响;最后,依据有限元模拟的结果,实验制备了多层DLC薄膜,通过测试薄膜力学及摩擦学性能,研究了多层薄膜的承载能力。主要结论如下:a.过渡层基本不改变DLC薄膜的结构,不同过渡层DLC薄膜的内应力与各材料之间的线膨胀系数有关,Si/DLC薄膜具有最低的内应力(~0.44GPa),Cr/DLC薄膜具有最高的临界载荷(~25.42N);基底偏压对DLC薄膜结构、力学和摩擦学性能影响最大,随基底偏压的升高,薄膜的石墨化程度加重,硬度、杨氏模量和内应力逐渐降低;偏压-800V时薄膜具有最高的结合强度(~25.32N),且呈现了较低的摩擦系数(0.05)和较长的磨损寿命。b.不同膜层顺序双层DLC薄膜系统的应力/应变分布相似,最大径向压应力出现在压头底部薄膜表面,最大的剪切应力出现在远离对称轴薄膜内部,塑性应变仅出现在基底;软-1000V/硬-800V和软-1000V/硬-600V薄膜系统具有较低的径向应力、剪切应力、等效应力和弹/塑性应变;调制周期的增加不仅改变了系统的应力/应变分布,而且大大降低了应力最值,超过2周期应力最值逐渐升高;随调制比例(即硬薄膜厚度)的增加,径向应力最值逐渐降低,剪切应力最值先增加后降低,等效应力最值逐渐增加;综合分析有限元模拟的结果,膜层顺序(软-1000V/硬-600V、软-1000V/硬-800V和软-1000V/硬-400V)、调制周期(2、3和4周期)和调制比例(1:1、1:2和1:3)薄膜系统具有较高的承载能力。c.多层结构的引入提高了DLC薄膜的承载性能,相对于单层DLC薄膜,多层DLC薄膜具有更高的临界载荷和承载能力。不同结构多层DLC薄膜实验研究与有限元模拟结果基本一致,软-1000V/硬-600V、软-1000V/硬-800V、软-1000V/硬-400V薄膜系统摩擦失效载荷分别为11、17、10N;调制周期的增加大大提高了薄膜与基底的结合强度(~31N),3周期薄膜系统硬度最高(~18.68GPa),2、3、4周期薄膜系统摩擦失效载荷分别为14、17、10N;调制比例对多层薄膜的硬度和临界载荷影响不大,软硬膜厚比1:2系统具有最低的内应力(~0.86GPa)且呈现了稳定且较低的摩擦系数,1:1、1:2、1:3薄膜系统摩擦失效载荷分别为17、14、10N。
[Abstract]:In this paper, TC4 alloy was used as the research object. Firstly, Diamond-like carbon DLC thin films with Cr-Ti and Si transition layers were prepared by unbalanced magnetron sputtering technique. The effect of transition layer on the structure and properties of DLC films was investigated.The relationships between reactive magnetron sputtering parameters (substrate bias, deposition pressure, methane flux and sputtering power) and the structure, mechanical and tribological properties of DLC films were investigated.The effects of modulation period and modulation ratio on the load-carrying capacity of multilayer DLC thin films were simulated by finite element method. Finally, according to the results of finite element simulation, multilayer DLC thin films were fabricated experimentally.By testing the mechanical and tribological properties of the multilayer film, the bearing capacity of the multilayer film was studied.The main conclusions are as follows: a.The structure of DLC thin film is not changed by the transition layer. The internal stress of DLC thin film in different transition layer is related to the linear expansion coefficient between different materials. The Si / DLC film has the lowest internal stress and the highest critical load is 0.44 GPA / DLC thin film, and the substrate bias voltage has the highest critical load on the structure of DLC film.The influence of mechanical and tribological properties was the greatest. With the increase of substrate bias, the graphitization degree of the film increased, hardness, Young's modulus and internal stress gradually decreased.The film has the highest bonding strength (25.32 NV) and the lower friction coefficient (0.05) and the longer wear life (.b.) at the bias voltage of -800V.The distribution of stress / strain in different film sequences is similar. The maximum radial compressive stress appears on the surface of the film at the bottom of the head, the maximum shear stress occurs in the thin film far from the symmetry axis, and the plastic strain appears only on the substrate.The soft -1000V / hard-800V and soft-1000V / hard-600V thin film systems have lower radial stress, shear stress, equivalent stress and elastic-plastic strain, and the increase of modulation period not only changes the stress / strain distribution of the system, but also greatly reduces the stress maximum.With the increase of modulation ratio (that is, the thickness of hard film), the maximum value of radial stress decreases gradually, the maximum value of shear stress increases first and then decreases, and the maximum value of equivalent stress increases gradually.The results of finite element simulation show that the thin film systems have high load-carrying capacity (soft -1000V / hard-600V, soft-1000V / hard-800V and soft--1000V / hard-400V) and modulation ratios of 1: 1: 1: 2 and 1: 3).The introduction of multilayer structure improves the bearing capacity of DLC thin films. Compared with monolayer DLC thin films, multilayer DLC thin films have higher critical load and bearing capacity.The experimental results of multilayer DLC thin films with different structures are in good agreement with the results of finite element simulation.杞，

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