类金刚石薄膜掺杂作用机理及其摩擦学性能

发布时间：2018-06-02 18:15

本文选题：物理气相沉积 + 类金刚石薄膜　；参考：《华南理工大学》2016年博士论文

【摘要】：类金刚石(diamond-like carbon)薄膜具有高硬度、高弹性模量、优异的减摩耐磨性能、良好的光透过性、较强的化学稳定性和生物相容性等优异的性能,在太空机械、工模具、汽车、电子器件、光学、生物医学等领域拥有广阔的应用前景。然而,大量的研究发现类金刚石薄膜(DLC)中存在着很大的残余应力,不仅削弱了薄膜与基体之间的结合强度导致薄膜在服役过程中提前剥落失效,还限制了薄膜的沉积厚度,此外DLC薄膜还存在摩擦学行为对服役环境敏感性高的缺点,这些因素均限制了DLC薄膜在工业中的大规模应用。为了改善DLC薄膜的固有缺陷,满足工业应用的要求,本文通过金属、非金属以及化合物异质掺杂的方法对类金刚石薄膜进行改性,针对高温、高湿、干燥、贫油等不同的摩擦磨损服役工况,制备出了综合性能优异的掺钨DLC薄膜、掺硅DLC薄膜和WS_2掺杂DLC薄膜。采用磁控溅射和阳极层流型离子源复合沉积技术在H13热作模具钢和Si(100)基体表面制备了钨元素掺杂的DLC薄膜,以减小DLC薄膜中的残余应力、提高薄膜在高温环境中的热稳定性和减摩耐磨性能。为了减小薄膜与基体之间的物理失配、缓解界面应力并提高膜基结合强度,本试验通过工艺设置在DLC薄膜和基体之间构筑了Cr/CrN/CrNC/CrC梯度过渡层,大幅度地提高了DLC薄膜与基体间的结合强度。最终在H13钢表面沉积的掺W类金刚石薄膜的厚度可达3.51μm,膜基结合强度达HF2级,薄膜的显微硬度可达2289HV。采用TEM、SEM、XRD等检测方法对掺W类金刚石薄膜的微观结构和化学成分进行分析,发现W元素是以WC1-x纳米晶团簇的形式弥散地镶嵌在DLC薄膜三维碳基网络中,构成了纳米晶-非晶复合结构。随后本文系统地研究了掺W类金刚石薄膜从室温25℃到500℃温度范围内的摩擦磨损行为,得到的试验结果表明:在DLC薄膜中掺杂W元素不仅可以降低薄膜内应力和提高膜基结合力,还能提高薄膜在高温条件下的稳定性。在200℃以下能保持结构和摩擦学性能的稳定性,300℃加热时薄膜会发生部分石墨化,同时表面开始氧化,薄膜的耐磨损性能开始下降;400℃时氧化严重,薄膜中的C大量损失,薄膜主要由WO3相组成疏松的结构,薄膜的耐磨损性能将显著降低;500℃时其摩擦系数仍能保持在0.15以下,但其磨损率要远高于25℃~200℃温度范围内磨损的样品。采用中频磁控溅射和离子源辅助沉积技术,通过正交试验优化工艺参数,在Cr12MoV模具钢和Si(100)表面成功地制备了膜层结构细腻、致密的含氢掺硅DLC薄膜。Si元素掺杂含量是影响薄膜机械性能和摩擦学性能的关键因素,当Si含量为3.75at.%时,Si-DLC薄膜的硬度为2039HV,膜基结合强度在30N以上。此外,Si元素的掺入还可以降低薄膜摩擦学性能对摩擦环境湿度的敏感性,当Si含量在3.38~3.75 at.%范围时,Si-DLC薄膜在高湿度和低湿度条件下的摩擦系数均可稳定在0.13左右。为了使DLC薄膜能够同时适应多种服役环境,采用中频磁控溅射和离子源辅助沉积技术在9310渗碳钢、TC4钛合金、K20硬质合金三种基体上制备了掺WS_2类金刚石薄膜。WS_2掺入DLC薄膜后是以WC1-x和WS_2纳米晶团簇的形式弥散分布于碳基网络之中,使得W-S-C复合薄膜既具有DLC薄膜高硬度、高耐磨性能,又拥有WS_2良好的自润滑性能。将制备的W-S-C复合薄膜样品分别放在干燥的氮气、湿润的大气、油润滑等环境中进行摩擦磨损试验,试验结果证实复合薄膜样品在不同的摩擦条件下均具有很低而且稳定的摩擦系数。其中,在干燥氮气气氛中的摩擦系数可低至0.03,在油润滑协同下的摩擦系数为0.04,在大气环境中无油润滑条件下的摩擦系数约0.15,此外在大气环境中和9310对偶副对磨时的磨损率可低至9.105×10~(-8)mm3·N~(-1)·m~(-1)。
[Abstract]:Diamond like (diamond-like carbon) films have high hardness, high modulus of elasticity, excellent antifriction and wear resistance, good light transmittance, strong chemical stability and biocompatibility. It has broad application prospects in space machinery, tooling, automobile, electronic devices, optics, biomedicine and other fields. It is found that there is a large residual stress in the diamond like film (DLC), which not only weakens the bonding strength between the film and the matrix, but also causes the premature failure of the film in the process of service, but also restricts the deposition thickness of the film. In addition, the DLC film has the disadvantages of high sensitivity to the service environment with tribological behavior. In order to improve the inherent defects of the DLC film in the industry, in order to improve the inherent defects of the DLC film and meet the requirements of industrial application, this paper has modified the diamond like film through the heterogeneous doping of metal, nonmetal and compound, and made a comprehensive synthesis for the different friction and wear service conditions of high temperature, high humidity, dry, poor oil and so on. Tungsten doped DLC films, silicon doped DLC thin films and WS_2 doped DLC films have excellent properties. The DLC films doped with tungsten elements are prepared by magnetron sputtering and anodic laminar ion source composite deposition on the H13 hot working die steel and Si (100) matrix to reduce the residual stress in the DLC film and improve the thermal stability of the film in the high temperature environment. In order to reduce the physical mismatch between the thin film and the matrix, alleviate the interfacial stress and improve the bonding strength of the film base, the Cr/CrN/CrNC/CrC gradient transition layer was constructed between the DLC film and the matrix, and the bonding strength between the DLC film and the substrate was greatly improved. Finally, the surface of the H13 steel was deposited on the surface of the steel. The thickness of W doped diamond like diamond films can reach 3.51 mu m, the bonding strength of the film base is HF2, the microhardness of the film can reach 2289HV. by means of TEM, SEM, XRD and other detection methods, the microstructure and chemical composition of the diamond doped diamond films are analyzed. It is found that the W element is inlaid in the DLC film three-dimensional carbon based network in the form of WC1-x nanoclusters. The nanocrystalline amorphous composite structure is formed in the collaterals. Then the friction and wear behavior of W doped diamond like diamond films from 25 to 500 C is systematically studied. The results show that the doping of W in the DLC film can not only reduce the internal stress of the film and increase the bonding force of the film, but also improve the high temperature of the film. Under 200 c, the stability of the structure and tribological properties can be kept below 200 c. When the film is heated at 300 C, the film will be partially graphitized and the surface begins to oxidize, and the wear resistance of the film begins to decrease; at 400 C, the oxidation is serious, the loss of the thin film is large, the thin film is mainly composed of the structure of the WO3 phase and the wear resistance of the film. The loss performance will be reduced significantly, and the friction coefficient can remain below 0.15 at 500 C, but its wear rate is much higher than that of the samples worn within the temperature range of ~200 C at 25 C. Using medium frequency magnetron sputtering and ion source assisted deposition technology, the membrane structure is successfully prepared on the surface of Cr12MoV die steel and Si (100) by orthogonal test. The content of the dense and dense.Si doped DLC film containing hydrogen is the key factor affecting the mechanical properties and Tribological Properties of the thin film. When the Si content is 3.75at.%, the hardness of the Si-DLC film is 2039HV and the adhesion strength of the membrane is above 30N. In addition, the incorporation of Si elements can also reduce the sensitivity of the tribological properties of the film to the humidity of the friction environment. When the content of Si is in the range of 3.38~3.75 at.%, the friction coefficient of Si-DLC film can be stable at about 0.13 under the condition of high humidity and low humidity. In order to make DLC film adaptable to various service environments at the same time, medium frequency magnetron sputtering and ion source assisted deposition technology are used in the 9310 infiltration carbon steel, TC4 titanium alloy, and K20 cemented carbide three kinds of matrix. The WS_2 doped diamond like thin film.WS_2 doped DLC thin film is dispersed and distributed in the carbon based network in the form of WC1-x and WS_2 nanocrystalline clusters. The W-S-C composite film has the high hardness, high wear resistance and good self lubrication performance of the DLC film, and the samples of the prepared W-S-C composite thin films are in dry. The friction and wear tests of nitrogen, moist atmosphere and oil lubrication have been carried out. The results show that the composite film samples have a very low and stable friction coefficient under different friction conditions. The friction coefficient in the atmosphere of dry nitrogen can be as low as 0.03, and the friction coefficient of oil lubrication is 0.04, in the atmosphere environment. The friction coefficient of oil free lubrication is about 0.15, and the wear rate in the atmosphere and 9310 pairs of pairs can be as low as 9.105 x 10~ (-8) mm3. N~ (-1). M~ (-1).
【学位授予单位】：华南理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG174.4

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