【作者】 张以忱；

【导师】 马德纯；

【作者基本信息】 东北大学 ， 流体机械及工程， 2008， 博士

【摘要】 目前,薄膜技术正朝着多元化、梯度化、复合化的方向发展。提高薄膜体系力学性能的有效工艺手段之一是制备多层复合膜,并在考虑多层复合膜构成组元的性质和沉积条件相关性的基础上优化薄膜的沉积工艺。在这种背景下,对不同类型的Ti(C,N), (Ti,Al)N, DLC硬质薄膜及各种多层复合膜的制备技术进行研究是必要的,对拓宽此类硬质膜的应用有较大的现实意义。硬质膜系的薄膜具有良好的应用前景,但是目前传统制备硬质薄膜的工艺主要是电弧离子镀、PCVD或者直流反应磁控溅射技术。而这些技术都存在着一些不足,例如电弧离子镀技术所制备的薄膜中含有大颗粒,表面粗糙度较大；直流反应磁控溅射则存在阴极靶容易中毒、离化率低、溅射效率低和阳极消失等缺点,导致产生镀膜工艺不稳定、膜基结合力差以及PCVD的尾气污染等问题。基于此,本论文利用国家863计划项目(2001AA338010)的资助,采用多功能渗镀复合镀膜设备,将中频孪生靶溅射与非平衡磁控溅射技术结合,采用离子束辅助沉积技术,在不同材料的基体上制备出不同膜系的无氢DLC (α-C)、含氢DLC (α-C:H)、掺杂氮DLC (α-C:N、α-C:H:N)、Ti(C,N)系列以及不同Al含量的(Ti,Al)N硬质复合薄膜。利用SEM、XRD、激光Raman光谱仪、XPS、微纳米力学综合测试仪(CMS)、触针式轮廓仪、显微硬度计、摩擦磨损试验机、色差仪等作为测量分析手段,对所制备的不同种类的硬质复合薄膜试样进行分析,并重点研究以Ti(C,N)、TiAlN和DLC薄膜为主体的多层梯度复合膜层的结构(例如：复合膜中不同的中间层对薄膜整体附着力和性能的影响)和制备工艺参数(例如,工作气氛(流量)与掺杂量、基体偏压、基体温度和霍尔离子流等)对薄膜的各项性能(如,薄膜相结构、表面颜色、粗糙度、摩擦系数、硬度和膜基结合力等性能)的影响,为多层复合硬质薄膜的工业化应用提供实验依据。论文工作具有以下特点,得到的主要实验结果及分析研究结论如下：(1)在同一台渗镀复合镀膜设备上,通过改变靶材和靶电源接法,分别采用离子束辅助中频非平衡磁控溅射和反应溅射工艺制备Ti(C, N)系列复合薄膜、无氢DLC(α-C)复合薄膜、含氢DLC (α-C:H)复合薄膜、掺杂氮DLC复合薄膜及Ti1-xAlxN复合薄膜等硬质复合薄膜,解决其它传统制备方法膜层粗糙、膜层内应力大等不足,而且使膜层的硬度和结合强度等性能不降低。(2) (Ti,Al)N薄膜中Al组分含量对薄膜的特性有很大影响,目前国内外绝大多数电弧离子镀及磁控溅射工艺都是采用钛铝合金靶制备(Ti,Al)N薄膜。但是由于TiAl合金在Al含量高时硬度高而且很脆,所以高Al含量的TiAl合金靶的制备比较困难,钛铝合金靶的造价比较高,而且靶材中钛、铝元素的含量在靶材制备时就已经固定,不能随意变化。本论文采用中频双靶非平衡磁控共溅射技术制备(Ti,Al)N薄膜,所用靶材为单独的Al靶和Ti靶,不仅可以解决TiAl合金靶制备的困难,而且在薄膜的沉积过程中,通过调节中频靶的功率(电流),可以容易地控制所沉积薄膜的化学成分,制备出高Al含量的(Ti,Al)N薄膜,大大节约了制备成本。(3)论文结合电弧离子镀与磁控溅射的各自优点,将电弧离子镀与非平衡磁控溅射工艺复合在同一台设备中进行镀膜,进一步扩展磁控溅射镀膜工艺的应用范围。利用电弧离子镀离化率高的优点,在离子轰击刻蚀清洗和镀复合膜的Cr底膜阶段采用电弧离子镀工艺,而在沉积主要膜层的过程中采用中频非平衡磁控溅射工艺,充分发挥两种工艺各自的优势,既可以获得较好的膜基结合力,又可利用磁控溅射工艺的慢生长特点生成致密光滑的膜层,有效减少了电弧放电带来的液滴等膜层缺陷,沉积出的硬质复合薄膜的膜基结合力好,膜层结构致密,表面光滑。(4)本论文制备了DLC/Ti(C,N)和DLC/(Ti,Al)N系列硬质复合薄膜,将DLC薄膜良好的自润滑性和耐腐蚀性与Ti(C,N)、(Ti,Al)N薄膜良好的力学性能结合,使不同薄膜的性能能够取长补短,综合性能得到提高。(5)为了克服DLC膜内应力高和附着性较差的弱点,本论文针对不同类型的DLC薄膜设计了多种多层梯度复合过渡膜系,制备了DLC/TiC/Ti(C,N)/TiN/Ti、DLC/Ti(C,N)/ TiN/Ti/Cr和DLC/(Ti,Al)N/(Ti,Al)/Cr复合薄膜,这样的膜系设计可以保证膜层从里到外的硬度逐渐提高,降低各单膜层间热膨胀系数差和膜层应力。对复合膜层的XPS深度剖析结果证实,该膜系可有效改善复合薄膜的力学状态,在基体与DLC膜之间形成了膜层成分和结构渐变的多层梯度复合膜系,使DLC薄膜中原本较高的残余应力大大降低,增强了薄膜的膜基结合力和力学综合性能。论文针对DLC/Ti(C,N)和DLC/(Ti,Al)N复合膜系设计采用了Cr做过渡层的底膜,利用Cr与钢基体之间的附着力强的特点,达到改善膜基界面结合力的目的。XPS膜层剖析结果证实：在薄膜的沉积过程中,Cr膜层经高能离子轰击诱发在钢基片-Cr界面上形成一个浓度梯度较小的Cr-基界面层,强化了与钢基体的结合强度。在Cr膜层之后沉积了Ti,Al混合膜层,Ti和Al的浓度分别呈一定的梯度上升和下降,转变为Ti, Al, N成份混合区,成分浓度是渐变的,从而在很大程度上降低了在膜层中的内应力。(6)通过实验总结得出中频非平衡磁控溅射和反应溅射技术制备Ti-N-C系列、无氢DLC (α-C)系列、含氢DLC (α-C:H)系列以及Ti1-xAlxN硬质复合薄膜的合适工艺。(7)基片温度对DLC薄膜的晶体结构和性能影响很大,基片温度在80℃～120℃时,是DLC薄膜形成最大sp3键含量的生长温度,DLC薄膜的硬度与弹性模量也到达最大；当温度继续增加时,由于薄膜中的sp3含量急剧下降,导致了薄膜的硬度和弹性模量的下降。(8)在较低的基片偏压下进行离子轰击更容易形成DLC薄膜,而在较高的偏压下,离子轰击作用增强,使薄膜表面温度升高,易使薄膜趋于石墨化。当基底偏压适当,离子轰击能量适中时,DLC薄膜中的sp3键含量达到最大,薄膜的硬度和弹性模量也达到最大值。较大的基底偏压,使高能粒子对膜层表面的反溅射作用增强,对薄膜表面产生了损伤,导致DLC薄膜表面粗糙度增加。而当基片偏压值在一定范围时,随着霍尔放电电流的增加,离子束流对薄膜表面的轰击密度增加,将膜层表面结合力不牢固的沉积粒子剥离掉。使得在不同基片材料上沉积的DLC薄膜的粗糙度下降,反射率增强,颜色逐渐变光亮。基片偏压对Ti (C, N)膜层晶体结构择优取向有影响,当基片施加的偏压较大时,膜层出现较明显的择优取向。(9)霍尔离子源放电电流对薄膜结构和性能影响较大。随着霍尔放电电流的增加,高能Ar离子对生长中的薄膜轰击密度加大,导致沉积的碳原子热扩散迁移能力增强,致使DLC薄膜中的sp3键含量逐渐下降,sp2键含量增加,趋向于形成热力学上更稳定的石墨结构,由于薄膜中的sp3键含量的下降,导致类金刚石薄膜硬度和弹性模量随之下降。增加霍尔离子源的放电电流,可使辅助轰击离子流的密度增强,离子对薄膜表面的反溅射作用去掉膜层表面沉积的松散粒子,并且提供能量使得膜层表面原子作适当迁移来改善膜层的致密性。随着霍尔放电电流的增加,薄膜表面逐渐光滑,摩擦系数略有下降趋势。霍尔离子流辅助沉积可使DLC薄膜的反射率增强,颜色变亮。在薄膜的制备过程中施加离子束辅助沉积,有利于增加膜层的结合力。(10)基片材料对薄膜的力学性能,特别是对薄膜的硬度和膜基结合强度影响较大。在不同硬度基体上制备同一种硬质膜,膜层的硬度和失效方式不同,膜基结合强度也不同。在同一种基片材料上沉积不同过渡膜系的复合薄膜,薄膜的力学性能也有差异。基体和膜层材料的性质越接近,膜层的力学性能越好。(11)沉积Ti(C,N)薄膜时,随着通入氮气中的乙炔的比例增加,Ti(C,N)膜层的硬度下降,氮气和乙炔的进气比例应大于3：2：TiN膜层颜色对工作气氛比较敏感,非平衡磁场虽然对空间的离子浓度有一定的增加作用,然而在整个磁控溅射的过程中空间的等离子体密度仍然比较小的情况下,反应溅射中工作气氛的微小变化会引起表面膜层颜色相当大的变化。随着乙炔进气量的增加,TiC/Ti(C,N)/TiN/Ti膜层的对各种波段的光波的吸收增加,反射率减少,膜层的颜色变黑；当乙炔的进气流量增加到300sccm以后膜层会从无择优取向变成(111)面的择优取向。沉积掺杂氮a-C：N膜时,随着反应气体中N2的增加,a-C：N薄膜的沉积速率逐渐增加,薄膜的表面粗糙度增大。Ar/N2流量比例对薄膜的结构和力学性能有影响。当Ar/N2=4.245：1时,a-C：N薄膜中的金刚石相sp3键最多,薄膜的硬度和弹性模量最大,分别为17.151GPa和179.838GPa；当N2流量比例继续增大时,由于薄膜中形成大量的碳氮键造成薄膜硬度和弹性模量减少。a-C：N薄膜的颜色主要是黑色。随着N2量的增加,薄膜颜色逐渐发红。沉积a-C：H薄膜时,当C2H2流量逐渐增加时,C离子增多,a-C：H膜的沉积速率相应增大。同时靶表面产生中毒现象,靶上杂质被溅射到薄膜上,使薄膜逐渐变的粗糙；a-C：H膜的颜色随C2H2量的增多,颜色逐渐变黑。C2H2进气流量对薄膜结构的影响不大；随C2H2流量增大,a-C：H薄膜的自润滑作用增强,摩擦系数减小。在a-C：H薄膜中掺杂N2时,随着N2气流量的增加,a-C:H:N薄膜中的sp3键的含量逐渐增大；当N2流量等于30sccm时,薄膜中的sp3键的含量达到最大。掺氮后,a-C:H:N膜层颜色为黑色略带红色。随掺氮量增多,a-C:H:N薄膜的摩擦系数呈下降趋势,掺氮对改善薄膜的摩擦性能有益。(12)基体材料镀DLC薄膜后,由于DLC膜取代了氧化膜层,从而显著提高基体电极的抗腐蚀能力。显微镜观察结果和动电位扫描实验结果都说明DLC膜有很好的抗腐蚀能力。(13)薄膜中的Al含量对Ti1-xAlxN复合薄膜的硬度的晶体结构、硬度和结合力等力学性能影响很大,当Al含量增多时,(Ti,Al)N薄膜的晶体结构由立方结构向AlN结构转化,从在(111)面择优生长转变为在(200)和(220)面生长趋势增强。随Al含量增多,Ti1-xAlxN薄膜的硬度先增大,后减小。薄膜中的Al含量在51at%时Ti1-xAlxN薄膜的硬度和膜基结合力最大,在高速钢基片上沉积的薄膜硬度为2078HV,临界载荷Lc2为50N。该硬度比采用相同基片材料,用磁过滤阴极真空电弧离子镀工艺沉积的(Ti,Al)N薄膜的硬度略高。Al的适量引入可使Ti1-xAlxN薄膜的摩擦系数降低。当Al含量小于一定限值时薄膜的摩擦系数随Al含量增多而减小,在x为51at%时达到最小值0.14,随后随Al含量的增加迅速变大。(14)与电弧离子镀制备的类似薄膜相比,中频非平衡磁控反应溅射所制备的薄膜表面更加光滑,而颜色与电弧离子镀制备的薄膜接近,亮度更高；中频非平衡磁控溅射镀制的硬质复合膜层与用电弧离子镀技术镀制的薄膜的硬度和膜基结合强度基本相同。更多还原

【Abstract】 The thin film technology is advancing the diversified, gradient and composite direction at present. Preparing multi-layer composite coating, and optimizing the deposition process considering properties of composite element and relevance of deposition conditions, is the effective means to improve coatings’mechanical properties. Under these circumstances, it is necessary to study on different types of Ti (C, N), (Ti, Al) N, DLC hard coatings and various multilayer composite coating preparation technology, which has greater practical significance for expanding the application of such hard coatings.Hard film has a good prospect, but traditional hard film preparation process is mainly arc ion plating, PCVD and DC reactive magnetron sputtering technology, which all have some disadvantages, for example, film prepared by arc ion plating technology contains droplets, and the surface roughness is great; while DC reactive magnetron sputtering has such problems as cathode target poisoning, low ionization rate, sputtering efficiency and anode disappearing which leads to instability coating process, bad binding force between film and substrate, PCVD exhaust pollution, and so on.Supported by National High Technology Research and Development Program of China (863 Program) (No.2001AA338010) funding, different film systems of non-hydrogen DLC(α-C), hydrogen DLC(α-C:H), nitrogen-doped DLC(α-C:N,α-C:H:N), Ti(C,N) series and different Al content (Ti, Al) N hard composite film are fabricated on different materials with multifunctional infiltration composite coating equipment by ion beam assisted deposition technology combined with MF twin target sputtering and unbalanced magnetron sputtering technology.Using SEM, XRD, Laser Raman spectrometer, XPS, Micro-nano mechanical testing instrument (CMS), Inconsistent stylus profilometer, micro-hardness tester, Triometer tester, spectrophotometer, etc., the analysis of those hard composite film samples are conducted. The research is focused on influence of the structure and fabricated parameters (such as, the working atmosphere (flow) and the doping amount, substrate bias, substrate temperature and Hall ion current, etc.) of multilayer gradient composite film like Ti(C,N), TiAlN and DLC film (for example, the influence of different middle layer in composite film on the overall adhesion and performance) on the properties of thin films (such as, film structure, surface color, roughness, friction coefficient, hardness and film-substrate binding force, etc.). It provides the experimental basis for the industrial application of multilayer hard composite film.The experimental results and the conclusions of the analysis are listed as the following:(1) Using the same composite coating equipment, the Ti(C,N) series composite film, non-hydrogen DLC(α-C) composite film, hydrogen DLC(α-C:H) composite film, nitrogen-doped DLC composite film and Ti1-xAlxN composite film, etc., are prepared with ion beam assisted MF unbalanced magnetron sputtering and reactive sputtering process by changing the target material and the connection of target power. It resolves the defects of film by other traditional method, such as rough surface, large internal stress, and the hardness, adhesion strength and other properties of films are maintained.(2) The Al content of (Ti, Al) N film has great influence on film properties. At present, domestic and international arc ion plating and magnetron sputtering process are based on titanium aluminum alloy target to fabricate (Ti,Al) N film. However, the high Al content of TiAl alloy makes the alloy hard and brittle, so the preparation of TiAl alloy target with high Al content is very difficult, and the price of TiAl alloy target is relatively high. At the same time, the titanium and aluminum content of target have been fixed during preparation, can not arbitrarily change. In this paper, MF twin-targets unbalanced magnetron sputtering technology is used to prepare (Ti, Al) N film. The target material used is separate Al and Ti. It can not only solve the difficulties of TiAl alloy target on fabrication, but also easily control chemical composition of thin film during deposition processing by adjusting the power (current) of MF target. Using this technology, (Ti,Al) N film with high Al content can be prepared, and preparation cost can be greatly decreased.(3) Combining the respective merits of arc ion plating and magnetron sputtering, the arc ion plating and unbalanced magnetron sputtering are synthetically used in the same coating equipment. It further expands the scope of the application of magnetron sputtering. Taking into account its high ionization rate, arc ion plating process is used in ion bombardment cleaning and Cr basement coating preparing, while MF unbalanced magnetron sputtering process is used in the other coatings’deposition. The measure gives full play to their respective advantages of both technologies. Better binding force between substrate and film can be gotten, and the droplet by arc discharge is effectively reduced in magnetron sputtering process, so the deposited films are dense and smooth.(4) Ti(C,N)/DLC and (Ti,Al)N/DLC hard composite film series are prepared. Self-lubricating of DLC films and good mechanical properties of Ti(C, N), (Ti, Al)N films are combined to improve their comprehensive performance.(5) In order to change the high internal stress and poor attachment of DLC film, different types of multi-layer gradient composite DLC film system are designed and prepared, such as Ti/TiN/Ti(C,N)/TiC/DLC, Cr/Ti/TiN/Ti(C,N)/DLC and Cr/(Ti,Al)/(Ti,Al)N/DLC, which can ensure that hardness of films increase gradually from the inside to the outside, and lower the film stress and difference of thermal expansion coefficient between layers. The XPS analysis results on the composite film confirm that, the design can effectively improve the mechanical condition of composite film. The multi-layer gradient composite film system whose composition and structure change gradually between DLC film and substrate, makes higher residual stress in DLC film greatly reduced and enhance the film’s binding force and mechanical properties.Cr is chosen as the basement coating of the transition layers in Ti (C, N)/DLC and (Ti, Al)N/DLC composite film systems, considering that the adhesion is strong between Cr and steel, the use of Cr can effectively improve the interface bonding force. XPS analysis confirm that, a smaller concentration gradient Cr-substrate interface layer forms when Cr film is bombarded by high-energy ion during film deposition process, which reinforce the combination intensity with steel substrate. Ti, Al mixed film is prepared after Cr film deposition. Concentration gradient of Ti and Al rise and fall respectively, being a mixing zone of Ti, Al, N ingredients, so the concentration change gradually, thus reducing the internal stress in film to a large extent.(6) The suitable process of Ti(C,N) series, non-hydrogen DLC(α-C), hydrogen DLC (a-C:H), and Ti1-xAlxN hard composite films by MF unbalanced magnetron sputtering and reactive sputtering technology are concluded by experiment.(7) The crystal structure and performance of DLC film are greatly effected by substrate temperature. When substrate temperature is 80℃～120℃, the sp3 bond content of DLC film is the largest, and the film’s hardness and Young’s modulus also reaches the largest. While when the temperature continues to increase, the hardness and Young’s modulus decline due to the sp3 content decrease sharply in the films.(8) DLC film is liable to form at lower substrate bias, while at a higher bias, the ion bombardment enhances, so the temperature on film surface increases and film tends to graphitization. When the substrate bias is appropriate, the ion bombardment energy is moderate, and sp3 bond content in DLC film reach the largest, film hardness and Young’s modulus also reach the maximum.When the substrate bias is larger, the inverse sputtering effect of high-energy particles on the film enhances and cause surface damage, which leads to DLC film’s surface roughness increases. When substrate bias is in certain range, with the increase of Hall discharge current, ion beam bombardment density on the film surface increases, so the fragile deposition particles on surface will strip off, and roughness decreases, reflectivity increases, color becomes bright gradually for DLC film.Substrate bias influences the preferred orientation of Ti(C,N) film’s crystal structure, when substrate bias is larger, the film show more obvious preferred orientation.(9) Hall ion source discharge current has larger influence on the structure and properties of film. With the increment of Hall discharging current, the thermodynamic steady graphite structure is liable to form because the bombardment of energetic particles on growing film results in the active shift of carbon atoms. In the meantime, the sp2 content increase, and the sp3 content, hardness and Young’s modulus all decrease gradually.With the increase of the Hall discharge current, the film becomes smooth and the friction coefficient decline, which can be explained that the inverse sputtering of particles on the film surface is strengthened because of the enhanced current, and the atoms supplied with energy can shift on film surface to improve the film’s compaction as a result. Hall ion assisted deposition can effectively enhance the reflectivity, bright color and increase film’s bonding force.(10) The substrate material has great influence on film’s mechanical performance, especially hardness and binding energy. The testing hardness, failure mode and binding force of the same hard film on different hard substrate are all different. The mechanical performance of composite films with different transition layers on the same substrate is also different. The closer the characters of film and substrate material are, the more remarkable the surface modification effect of film is.(11) When depositing Ti(C,N) film, its hardness decreases with the increase of acetylene-nitrogen ratio. The nitrogen-acetylene ratio should be greater than 3:2. The color of TiN coating is sensitive to the working atmosphere. The unbalanced magnetic field can increase the plasma concentrations in space, but when the plasma density is relatively little, small change of plasma density during magnetron sputtering process will cause considerable change in the coating’s color. With the increase of acetylene inlet flow, Ti/TiN/Ti(C,N)/TiC film’s absorption of various band light increases, and the reflectivity reduces. The color of film turns black. When the acetylene inlet flow increases to 300 sccm, the film will turn to a preferred (111) orientation from non-preferred orientation.When depositing nitrogen-doped a-C:N film, with the increase of N2 content in reaction gas, the deposition rate of a-C:N film gradually increases, and the film’s surface roughness increases. The flow ratio of Ar/N2 has influence on the film structure and mechanical properties. When Ar/N2 is 4.245:1, diamond phase sp3 bond content in the a-C:N thin film is the largest, the hardness and Young’s modulus of film are also the largest,17.151 GPa and 179.838GPa, respectively. With the continual increase of N2 ratio, film hardness and Young’s modulus reduce because of the forming of lots of carbon-nitrogen bond, when the color of a-C:N film mainly takes on black. With the increase of N2, the film color turns red gradually.When depositing a-C:H film, with the gradual increase of C2H2, C ion increases, so the a-C:H film deposition rate correspondingly increases. At the same time, the film surface becomes rough as a result of targets poisoning and impurities on targets being sputtered to the film. With the increase of C2H2, the color of a-C:H film gradually becomes black, the self-lubricating of a-C:H film enhances and the friction coefficient decreases. C2H2 flow has little influence on film’s structure.When doping N2 inα-C:H film, with the increase of N2 flow, the sp3 bond content inα-C:H:N film gradually increases. When N2 flow is 30 sccm, the sp3 bond content in film reaches the biggest. After the nitrogen is doped, the color of a-C:H:N film takes on black with slightly red. With the increase of doped nitrogen content, the friction coefficient of a-C:H:N film shows a decreasing trend, so nitrogen-doped can improve the film’s tribological properties. (12) The corrosion resistance of substrate plated with DLC film is significantly improved, for DLC film replaces the oxide layer. The microscope observation and potentiodynamic canning result have indicated that the DLC film have good corrosion resistance.(13) The Al content has great influence on the crystal structure, hardness and mechanical properties of composite Ti1-xAlxN film. When the Al content increases, the crystal structure of (Ti,Al)N film change from cubic crystal structure to hexagonal AlN structure, and the (111) preferred growth turns to (200) and (220) preferred orientation.With the increase of Al content, the hardness of Ti1-xAlxN film firstly increases and then decreases. When the Al content in Ti1-xAlxN film equals 51 at%, the hardness and film-substrate binding force is the largest. When the critical load Lc2 is 50N, hardness of film deposited on high-speed steel is 2078HV, which is slightly greater than the (Ti,Al)N film prepared by magnetic filtered cathodic vacuum arc ion plating process when the substrate material is same.Suitable Al addition can reduce the friction coefficient of Ti1-xAlxN film. When the Al content is less than certain value, the friction coefficient of film decreases with the increase of Al content, the minimum value reaches 0.14 when x equals to 51 at%, and then turns greater rapidly with the increasing of Al content.(14) Compared with the film prepared by arc ion plating, the film prepared by MF unbalanced magnetron reactive sputtering is much smoother, and the color is close to that by arc ion plating, but brighter; the hardness and binding strength of film prepared by MF unbalanced magnetron sputtering and arc ion plating are almost the same.更多还原