论文题目载能粒子沉积硬质润滑薄膜

1、论文题目：载能粒子沉积硬质润滑薄膜作者简介：于翔，男， 1969年6月出生，2001年9月师从于中国地质大学（北京）王成彪教授，于2007年6月获博士学位。中 文 摘 要提高钻探机具零件耐磨、耐蚀性能及其在苛刻工况条件下的使用寿命是地质工程领域中急待解决的关键技术问题。用传统的表面强化技术和单一薄膜材料不能满足机具零件在苛刻地质工况条件下的使用要求，需要针对性地采用多元材料和多种表面强化方法改善零件的摩擦学性能。但目前关于零件表面强化实用技术的系统研究还相当匮乏，急待探索零件耐磨减摩中重要的基础性科学问题和解决其中的关键技术问题，为拟定有效的零件表面强化实用技术，同时为研制新型钻探机具、提高钻

2、探效率提供试验数据和理论指导。本文提出采用载能粒子沉积硬质润滑薄膜来强化金属基材表面，解决星际钻探和超深钻探等机具零件磨损失效问题的理论构想。针对传统表面强化方法难以实用化的症结，硬质润滑薄膜的研究思路是“三化”合一，即将多组元复合化、晶粒纳米化和多层梯度化有机地统一于一体；依此进行有关多元材料和多种方法的载能粒子气相沉积研究来满足不同工况条件下零件的表面强化要求。载能粒子沉积的硬质润滑薄膜具有特殊的结构和良好的综合特性： 高硬度和超高硬度赋予零件远优于基材的耐磨性； 自润滑和低摩擦系数能够大幅度提高摩擦副在苛刻工况条件下的使用寿命； 高的薄膜/基材结合强度能够保证镀膜件的可靠性； 平滑的表面

3、和几十纳米至数微米的厚度选择范围能够满足零件的加工精度和密封要求； 利用载能粒子沉积能够实现镀膜材料的“三化”，从而可根据特定的使用要求选择所需要的薄膜材料； 镀膜过程中没有污染。由于具有以上特殊的结构和良好的综合特性，载能粒子沉积硬质自润滑薄膜是极具应用潜力的先进表面强化技术，在机械加工、机械制造和航空航天工业中都有广泛的应用前景。本论文在评述钻探机具表面强化研究概状和热点问题的基础上，围绕载能粒子对气相沉积硬质摩擦学薄膜结构和综合摩擦学性能的影响这一中心，以多种载能粒子沉积技术为制备手段，以“三化”合一的研究思路合成出多种膜层结构细密且具有硬度高、摩擦系数低和膜基间结合力好特点的硬质润滑薄

4、膜，进行了零件摩擦学薄膜制备、结构、性能和应用的基础研究。系统考察了薄膜结构和综合摩擦学性能，比较了制备工艺和薄膜的交互作用，揭示了沉积工艺与薄膜结构、性能间的关系，探讨了载能粒子对薄膜结构和综合摩擦学性能的影响。试图为硬质润滑薄膜在易损件耐磨减摩应用中拟定有效的表面强化实用技术，同时为研制新型钻探机具、提高钻探效率和改善星际钻探等机具适用性提供新的技术。在大量试验和测试分析基础上，取得的创新性研究成果有：1） 利用0至200 eV低离化载能粒子通过复合表面改性处理合成了Si-B-N和MoS2复合薄膜。（1）以硼乙烷、硅甲烷和氮气为反应气体，用三极RF-DC-PECVD技术提供了制备BN薄膜的

5、新途径，在45号钢基材上制备出含有h-BN和c-BN混合相的Si-B-N复合薄膜，硅掺杂能降低膜层内应力并有利于形成厚膜，Si-B-N薄膜与钢基材间厚达数微米的渐变界面过渡层改善了膜基间结合力。结合Si3N4、MoS2和BN薄膜的优点，在钢基材表面上用RF-DC-PECVD法沉积Si-B-N复合薄膜和RF射频溅射MoS2基薄膜的复合表面处理改善了基材的力学性能，降低了基材的摩擦系数，提高了基材耐磨寿命。（2）从离子鞘和离子动力学的角度分析了DC负偏压对薄膜中c-BN相形成的影响。在沉积Si-B-N复合膜期间，需要有DC负偏压引起的离子轰击，形成c-BN相的适宜能量为-140 V -180 V。

6、（3）在大气和中真空条件下的试验结果表明，MoS2基固体润滑薄膜显著降低了9Cr18摩擦副的摩擦系数，在真空环境中润滑作用更加明显；干摩擦跃迁引起的表面硬化和表面粗糙度是影响9Cr18摩擦副大气环境滑动摩擦性能的重要因素。（4）精密角接触球轴承真空寿命试验结果显示，MoS2溅射膜等润滑的球轴承有效转数超过1×106 转。参照平均摩擦力矩的变化情况，将球轴承的固体薄膜润滑过程分为三个阶段：跑合、稳定和失效，MoS2薄膜的双向转移过程在稳定阶段中起到了重要润滑作用。提出的MoS2溅射膜润滑失效机理在改善球轴承润滑系统性能期间得到了证实。2）用数百eV的高离化载能粒子沉积了纳米晶超硬TiN

7、薄膜和ta-C（四面体非晶碳）薄膜。（1）以多弧离子镀系统在M2高速钢基体上制备出附着性好的纳米晶超硬TiN薄膜：在25 g载荷下显微硬度高达45 GPa，临界载荷Lc 56 N，TiN111、TiN200和TiN220的平均晶粒粒径分别是12.7 nm、19.7 nm和9.6 nm。HRTEM测试和XRD分析结果一致，显示出超硬TiN薄膜的硬度增强机理是： 在密排(111)晶面择优取向和择优生长； 粒径纳米化和 载能离子轰击引起的薄膜内应力增加。这种纳米晶超硬TiN薄膜的结构不同于国际上普遍认可的两种结构：（a）过渡金属氮化物纳米叠加层和（b）在非晶基质中嵌入过渡金属微晶，此试验结果对认识超

8、硬薄膜的硬度增强和成膜机理有创新意义。（2）以配有MAVVA源的磁过滤阴极真空弧系统分别在硅片、9Cr18钢和高速钢基材上制备出的超硬ta-C薄具有良好的综合摩擦学性能：纳米硬度超过40 GPa，膜基间结合力好，摩擦系数约0.1并在较长球盘试验期间保持稳定。在硅基材上制备了带有SiCx渐变界面层的ta-C薄膜；在9Cr18钢基材上的ta-C薄膜能够通过改善零件的表面摩擦学性能来大幅度提高9Cr18轴承的使用寿命；在高速钢基材上沉积的ta-C膜具有特别优良的综合摩擦学性能：显微硬度达76 GPa，附着力Lc达 41 N，摩擦系数低达0.11且可在16000 转数范围内保持稳定。sp3含量高的ta

9、-C膜的内应力很高，当膜厚超过1µm时，膜基结合力显著下降；在试验基础上，建立了ta-C膜的附着失效模型（即施加载荷和划犁作用引起的材料塑形变形）和摩擦磨损失效机理（即疲劳裂纹萌生和延伸）模型。3）用数百eV的中度离化载能粒子沉积了硬质Ti/TiN薄膜和含铬DLC（类金刚石碳）薄膜。（1）通过优化中频磁控溅射参数改善了含有Ti附着层和间隔层的Ti/TiN多层膜的表面缺陷密度和附着力。 在TiN薄膜表面不规则出现由液滴和坑组成的表面缺陷与中频对靶反应磁控溅射中起弧模式和靶中毒密切相关。正交设计和方差分析结果显示，靶电流对薄膜表面缺陷密度影响最大，气体压力对薄膜表面缺陷密度影响次之，基体

10、负偏压对表面缺陷密度影响最小；在优化条件下得到了缺陷密度低达58 defect/mm2的Ti/TiN多层膜。 随着Ti间隔层厚度的增加，多层膜的显微硬度降低，膜基间的结合力增加；Ti间隔层厚度超过临界值0.4 µm后，结合力有所下降。（2）利用中频对靶磁控溅射系统分别合成了硬质、超硬以及膜厚超过6 µm的无氢含铬DLC薄膜；考察了多层梯度结构和铬含量等对含铬DLC薄膜结构和性能的影响，探讨了载能粒子对无氢DLC形成的作用机理。 多层梯度结构能提高DLC膜硬度和改善其结合力；靶电流和基体负偏压影响DLC膜硬度，DLC膜硬度高达3246 GPa；在160 V偏压下合成DLC膜的

11、结合力Lc为65 N；钢基体上超硬自润滑DLC膜的平均摩擦系数低达0.08，且可在500 m滑动距离中保持稳定。 在脉冲DC模式下合成的DLC膜综合摩擦学性能优越：非常平滑的表面、硬度达26.66 GPa、结合力（Lc）高达55 N、摩擦系数低达0.08；三种模式中的反向电压幅值和持续时间和DLC膜性能差异密切相关。 厚达6 µm的含铬复合DLC膜表面平滑，具有致密的多层梯度结构，在250 g载荷下维氏硬度Hv为2560 kg/mm2，结合力的临界载荷Lc为52 N（在划痕最后阶段仍能够保持大部分薄膜完整），在较长滑动距离内平均摩擦系数为0.09。梯度多层结构设计有益于减轻DLC和钢

12、基体间的不匹配性；铬层和含铬层可改善膜/基间结合力，CrNz和CxCry层起有重要的支持作用。 铬含量和在非晶碳基质中形成的Cr/C纳米颗粒是影响薄膜性能的重要因素；在薄膜中掺杂适量铬元素和含铬纳米晶粒能够在降低薄膜内应力和摩擦系数的同时提高薄膜的硬度。 DLC成膜是在粒子流量和能量共同作用下体岛状金刚石微晶形成和生长的过程；金刚石微晶成核是在亚表面层发生的体凝聚过程。关键词：载能粒子沉积，硬质润滑薄膜，钻探机具易损件，薄膜结构，综合摩擦学性能Energetic-Particle Depositing Hard-Lubricated Films Yu XiangABSTRACTA key co

13、ncern in the field of geo-engineering is to improve the wear and corrosion resistance of the drilling tools so as to extend their service life under rigorous and severe working conditions. As the conventional techniques of surface enhancement and filming single-material coating cannot meet the requi

14、rement of drilling operations in rigorous and severe working environments, improvement of tribological properties of the components by composite materials and composite surface enhancements is thus essential and necessary. Currently, systematic research on the techniques for enhancing the surface of

15、 these types of components is still rather rare. Adequate technical solutions to the key problems and their significant scientific roles in wear-resistance and friction-reduction are still waiting to be explored. Such exploration enables: (i) the drawing up of an effective technique suitable for the

16、 surface enhancement; (ii) furnishing the geo-engineering industry with experimental data and theoretical pointers in deploying new drilling implements; and (iii) optimizing the drilling efficiency.This dissertation provides a new theoretical gist through the investigation of using energetic-particl

17、e-depositing hard-lubricated films to enhance the surface of metal substrate, and to cope with the wear failure problems in the extraterrestrial drilling, the super-deep well drilling, and other relevant drilling problems. Aiming at solving the failure of using traditional surface enhancement techni

18、ques to fulfill the application requirements, this specific research attempted to study the possible integration of the formation of (i) polycomponent composite, (ii) nanoscale grains, and (iii) graded multilayer in the hard-lubricated films. The integration was conducted on (i) vapor-deposited comp

19、osite filming and (ii) composite techniques so as to satisfy the surface enhancement requirements of the metal components under different working conditions.Energetic-particle-depositing hard-lubricated film has special microstructure to give good combined characteristics of: (i) high and super hard

20、ness for endowing better wear resistance of a component; (ii) self-lubrication and low friction coefficient for extending the servicing lifetime of friction pairs under arduous conditions; (iii) high film-substrate adhesion strength for warranting the reliability of the coated components; (iv) smoot

21、h surface with deposition thickness in range of few nanometers to several microns for satisfying the processing precision and sealing requirements of a component; (v) prefabricate-able of the anticipated film structures, nano-grain and graded multilayer of a composite by energetic-particle depositio

22、n technique, for accomplishing certain specific operating requirements; and (vi) pollution free in the coating processes. As energetic-particle-depositing hard-lubricated film is possible to facilitate the aforementioned microstructure and good characteristics, its relevant surface enhancement techn

23、ique gives great potentials to be applied in mechanical processing, mechanical manufacture and aerospace industries. In this dissertation, it firstly reviews the researches on surface enhancement of wearing parts for drilling implements, and goes on to explore the impact of energetic particles on th

24、e structural and combined tribological performance of various films. Several hard-lubricated films with combined characteristics of high hardness, low frictional coefficient, good film-to-substrate adhesion and fine dense microstructure have been synthesized. The design of these films normally invol

25、ves with the nanometric engineering of multilayered composites and the variation of layer gradients. The studies used several energetic-particle deposition techniques to improve the wear resistance of frictional pairs in drilling implements. The research fundamentally covered the preparation, the fo

26、rmation of microstructure, the creation of suitable properties and the adequate application of tribological films for the geo-drilling implements. The processing parameters for achieving the anticipated film microstructure and combined tribological properties were systematically investigated. The st

27、udies: (i) correlated the relation between the preparation process and the film properties; (ii) allowed to determine the relation of the deposition process, film structure and properties; and (iii) discussed the impact of energetic particles on the film structure and combined tribological propertie

28、s. By the observations in the studies, an effective and practical technique for enhancing the surface of wearing parts in drilling implements using hard-lubricated films was derived. Results of the studies offer useful theoretical pointers for: (i) developing new drilling implement, (ii) improving d

29、rilling efficiency and (iii) guaranteeing the adaptability of drilling components in extraterrestrial exploration. Results of the numerous experiments and testing analyses enable the drawing of following conclusions.1) Low-ionogenic energetic particles with 0200 eV were used to synthesize Si-B-N and

30、 MoS2 composite film by a composite surface modification technique. (1) The use of the triode RF-DC-PECVD technique with boran, silane and nitrogen as reactive gases allowed a new BN preparation method to be derived. Results showed the obtainment of the mixed state of h-BN and c-BN on the 45 steel.

31、It was found that silicon doping was able to reduce internal stress and could be used to form thick film. The creation of gradient transitional layer up to several microns thick improved the film-to-substrate adhesion. Benefiting from the combined advantages of Si3N4, MoS2 and BN films, the duplex t

32、reatment of the Si-B-N composite film by RF-DC-PECVD and the MoS2-based film by RF sputtering improved the mechanical and tribological properties of 45 steel substrate; it reduced the friction coefficient and prolonged the endurance life of the substrate. (2) This research also investigated the effe

33、ct of DC negative-bias on the c-BN phase formation in views of ion sheath and ion dynamics. DC negative bias to induce ion bombardment is an integrating function in Si-B-N composite film, and its most adequate energy level for forming c-BN was ranging between -140 V and -180 V. (3) The systematic ex

34、periments and analyses in atmosphere and vacuum showed that: (i) MoS2-based solid lubrication film reduced notably the frictional coefficients of 9Cr18 frictional pairs in both atmosphere and vacuum conditions; and (ii) the dry friction transition and surface roughness, tended to induce surface hard

35、ening, were the two important factors affecting the gliding frictional property of 9Cr18 frictional pair in atmosphere. (4) Lifetime test conducted for angular-contact ball bearing in vacuum gave a steady life of 1×106 revolutions for the ball bearing lubricated by MoS2-sputtered film. On the b

36、asis of the variation of average friction torques, the process of solid lubrication of the ball bearing can therefore be classified into three basic stages of (i) initial running-in, (ii) steady functioning to transfer mutually the MoS2 film, and (iii) failure initiation and failure. Among these thr

37、ee stages, the double-transfer stage of MoS2 film played an important lubrication role in the steady stage. Verification of the proposed lubrication failure mechanism of MoS2-sputtered film was made by the use of an improved lubrication system of the ball bearings.2) High-ionogenic energetic particl

38、es of several-hundred eV were used to synthesize nanocrystallite superhard TiN films and ta-C (tetrahedral amorphous carbon) films. (1) A multi-arc ion plating system was used to synthesize an adherent nanocrystallite superhard TiN film on M2 high-speed steel substrate. The synthesized film gave mic

39、rohardness up to 45 GPa measured under a 25g load indentation, critical load (Lc) 56 N, mean grain sizes of about 12.7 nm for TiN111, 19.7 nm for TiN200 and 9.6 nm for TiN220. Results of HRTEM studies on the superhard TiN film were consistent with those of XRD analysis. The hardness enhancement of t

40、he film was identified as due to the following mechanisms: (i) the preferred orientation and growth on the closed-packed plane (111), (ii) the formation of nanoscale crystalline grains and (iii) the intrinsic stress increase induced by energetic ion bombardment. The structure of such nanocrystallite

41、 superhard TiN film was different from the two commonly known structures of (a) forming transitional metal nitride heterostructures into nm-scale alternating layers and (b) imbedding transitional metal nitride nanocrystals within the amorphous tissues. These findings from the experimental results of

42、 this study significantly contributed to the scientific understanding in the field of hardness enhancement and formation mechanism of the superhard films. (2) A filtered cathodic vacuum arc system with MAVVA source was used to deposit superhard ta-C films on three individual substrates of (i) silico

43、n, (ii) 9Cr18 steel and (iii) high-speed steel. The synthesized ta-C films exhibited admirable combined tribological properties with (i) nanohardness over 40 GPa, (ii) good film-to-substrate adhesion, and (iii) frictional coefficient as low as 0.1 and maintaining stable in relatively long-duration b

44、all-on-disc test. Results of the studies indicated that: (a) the ta-C film on silicon substrate allowed gradient interface layer to be synthesized; (b) 9Cr18 substrate coated with the ta-C film improved the surface tribological properties and thus extended the service life of 9Cr18 bearing; (c) the

45、ta-C film coated on the high-speed steel substrate demonstrated superior mechanical and tribological properties, which gave nanohardness up to 76 GPa, adhesion Lc available at 42 N, frictional coefficient low to 0.11 and stable in range of 16,000 revolutions. The high internal stresses of ta-C films

46、 with high sp3 ratio decreased greatly the film-to-substrate adhesions when the film thickness was exceeding 1µm. On the basis of experimental data, two models of the adhesion damage mechanism (i.e. the generation of plastic flow of materials by the applied load and/or plowing) and the wear dam

47、age mechanism (i.e. the gradual evolution of fatigue crack in the film) of the ta-C films was established. 3) Medium-ionogenic energetic particles of several-hundred eV were used to synthesize hard Ti/TiN film and Cr-doped DLC (diamond-like carbon) film. (1) Improvement of the surface defect density

48、 and the adhesion of Ti/TiN multilayered films containing Ti interlayer and Ti buffer layer was achieved through optimizing the process parameters in a mid-frequency dual-magnetron sputtering. Results showed the irregular appearance of the surface defects including droplets and craters on the TiN fi

49、lm surface. The level of irregularity and the amount of such defects and craters were found to relate closely to the arcing modes and the target poisoning. Orthogonal design and variance analysis performed in this study revealed the impact of the target current on the defect density being greatly im

50、portant. It tended to diminish the effect of the gas pressure and the substrate bias voltages. Under the optimized parameters, defect density as low as 58 defects/mm2 was achievable in Ti/TiN film. With increasing the thickness of Ti buffer layers, the microhardness of multilayered film decreased an

51、d the adhesion increased. However, the adhesion tended to decrease when the Ti/TiN film thickness was beyond a critical value of 0.4 µm. (2) A mid-frequency dual-magnetron sputtering system was used to synthesize hydrogen-free Cr-doped DLC films. Some of the so-synthesized films were hard, some

52、 were superhard whilst others with thickness beyond 6 µm. Investigation was also conducted to study the influence of graded multilayered design and chrome content on the microstructures and properties of the Cr-doped DLC films. In addition, this dissertation also discussed the impact of the ene

53、rgetic particles on the hydrogen-free DLC film formation. The production of graded and multilayered structure in this research enhanced the hardness and improved the adhesion of the DLC film. This study also reflected the effect of the target current and the bias voltage on the hardness of the DLC f

54、ilm. The synthesized films gave hardness in range of 3246 GPa and adhension Lc of 65 N when synthesized at a bias voltage -160 V. The superhard lubricated DLC film deposited on the steel substrate had average friction coefficient as low as 0.08 that was almost stabilized in a sliding testing distance of 500 m. The DLC film coated with pulsed DC mode exhibited certain admirable combined tribological properties. Typically, it had very smooth surface, high microhardness (mornally 26.66 GPa), good adhesion o